How To Add A Resistor To A Speaker To Change Or Match Impedance

Maybe you’ve got some extra speakers lying around or just want to know how to add a resistor to a speaker to change its impedance. Either way, you’re in luck!

In this article, I’ll show you:

  • How to change (or match) speaker impedances using resistors (with great diagrams to follow!)
  • The disadvantages of using resistors to change the speaker impedance
  • What kind of resistors you’ll need
  • What to do if you can’t find exactly the right resistors (there are some handy ways around that!)
  • Where to buy the right resistors – without going broke, too!

What kind of resistors should you use for changing speaker impedance?

Audio power resistor examples

Examples of common “power” (high-power) resistors used for audio & speaker impedance needs. These are resistors built to handle the higher power levels put out by an amplifier or stereo.

To work with the higher output of amps and receivers, you’ll need to use power resistors when working with speakers.

A power resistor is just a larger-size resistor that can handle a lot more power & heat than the small ones commonly used on electronic boards. They’re actually fairly inexpensive, too ($5 or so for 2 to 4 in a pack), and are commonly used for custom speaker projects.

For speaker systems, I recommend using one with a power rating of 25 watts or more to be sure. For car stereos (not car amplifiers – those are higher power), you can often get away with around 10W to 15W.

Note: Resistance is usually described in units called Ohms, also commonly shown with the Greek omega “Ω” symbol.

Resistors to avoid

Example of standard electronic axial resistor

Shown here is an “axial” type resistor used for low-power electronics. These types of resistors aren’t suitable for working with speakers, audio, and other high power electrical circuits. Don’t use them for speakers as they can get extremely hot and potentially burn out.

While you might be tempted to try them, it’s important to avoid low-power (small) electronic resistors. These usually are rated for only about 1/8 of a watt to 1/2 watt. They’re simply too small to safely handle the large amount of heat that speakers and amps can dish out.

If you connect these to a high-power audio system they can become extremely hot, possibly causing burns or simply burn out altogether and cause failure (if you’re lucky) or even damage items they’re close to.

How to add a resistor to a speaker to change or match impedance

How to add resistor to speaker to change impedance diagram

You can change speaker impedance with resistors for two situations:

  1. To use a lower impedance speaker than you normally could with an amplifier or stereo.
  2. To use a higher impedance speaker where a lower one is needed (for example: speaker crossover designed only for a certain Ohm rating speaker).

Of the two cases, #2 is a lot less common. However, it’s really helpful when using speakers with crossovers and a few other situations you may run into.

If you’d like to use a higher speaker impedance than required for a stereo or amp, that’s normally not a problem. As long as the speaker impedance is equal or higher than a stereo or amp’s minimum Ohms rating it will work safely.

1. Using resistors to increase the total speaker impedance load

As shown from my diagram above, if you’re planning on using a lower impedance speaker you can add resistors in series in order to bring up the total impedance that the stereo or amp sees. This allows you to safely avoid overheating and burning out the electronics you’re connecting to.

To do so:

  • Connect a resistor with the right resistance (Ohms) value to bring up the speaker impedance as needed, and with at least 1/2 the rated power of the stereo or amp’s power output rating. (Ex.: for a 50W/channel stereo, you’ll pick a power resistor with a rating of 25W or more)
  • Insulate any exposed resistor leads so they can’t short to speaker wire or metal. Always make sure the speaker or resistor wire is fully covered & not exposed.

A resistor connected in series simply adds its resistance to the speaker impedance rating. (Ex.: A 4 ohm resistor plus a 4 ohm speaker = 8 ohms total).

2. Using resistors to decrease the total speaker impedance load

What’s great is that not only can you increase speaker impedance connected to an amp or receiver, but you can also effectively decrease it, too! This isn’t something you’ll run across very often, but there are some situations where it’s really handy to know how to do it:

  • Matching a different impedance speaker to speaker crossovers
  • Temporarily using extra speakers until you can get replacements for the original ones
  • Replacing obsolete speakers with the next best ones you could find, but need to match the impedance
  • Making use of discounted speakers you’ve gotten an excellent price on

In this case, you can decrease the total speaker load seen by connecting resistors in parallel.

To do so, it’s basically the same as connecting resistors in series but the main difference is that you’ll wire it in parallel:

  • Calculate the resistor value you need, in Ohms (this is usually the same as the speaker: for example, to have a crossover see a 4Ω with an 8Ω speaker, you can connect an 8Ω resistor in parallel
  • Add resistor to speaker wire & speaker: Connect the resistor to the positive and negative terminals of the speaker (you can do this using speaker wire – there’s no need to do it right at the speaker if that’s a problem)
  • Insulate & fully cover any exposed speaker wire or resistor leads so they can’t cause a short-circuit to nearby wiring or metal

Resistance in parallel is a little bit more complicated

How to calculate resistance impedance in parallel example diagram

Resistance in parallel is a little bit more complicated to figure out as far as the math is concerned. However, don’t worry! It’s actually fairly easy once you understand how it all works.

Resistance in parallel adds using this formula: R_total = 1 / [ (1/R1) + (1/R2) ]

However, for resistance/impedance in parallel, if the values are all the same you can just divide by how many there are.

What are the drawbacks of using resistors for changing speaker impedance loads?

How power is divided between speakers and resistors diagram

Diagram showing an example of how power is divided up when using resistors to change speaker impedance seen by an amplifier or radio.

One thing to be aware of that it’s not a perfect solution – there are drawbacks.

One of these is that when you add a resistor in series with a speaker, the power delivered is split between the two. The second one is that you can’t get the same maximum volume from your amp or radio as you could using only the correctly matched speaker impedance.

For example, let’s say you want to use a 4 ohm speaker with an 8 ohm minimum 100W/channel home receiver. Adding a 4 ohm resistor in series will bring the total resistance (speaker load, in Ohms) up to the safe level of 8Ω.

However, having a series resistor connected to the speaker means that each one gets only 1/2 of the total power delivered. That means when using a resistor to compensate for the wrong speaker Ohms value, you’ll always lose some power across it. That’s regardless of connecting before or after the speaker – that doesn’t matter.

Overall power available is reduced for parallel resistors, also

Similarly, when using resistors in parallel with a speaker to bring down the impedance the amp or stereo sees, they share power as well. For example, using an 8Ω resistor in parallel with an 8Ω speaker will give 4 ohms total. However, with a 50 watt per channel amp, the power is still divided between them, leaving a maximum of 25W to the speaker.

That’s because they share the amount of electrical current the amp can produce. It’s no longer fully available for only a single resistance (a single speaker).

Using resistors can sometimes slightly affect the sound

Speakers aren’t exactly like resistors – this means in some areas their impedance changes with the sound frequencies they’re playing. This is due to inductance and how the voice coil is affected by an alternating current (AC) musical signal.

This being the case, adding a resistor can slightly alter the sound as it can cause a speaker to behave slightly differently across the range of sound. However, for the most part, this isn’t normally a big issue.

Just be aware that if you notice a difference that may be why.

What if you can’t find exactly the right resistors?

Example of power resistors in retail store on display hooks

Shopping for the right value & power rating of resistors can be a pain! That’s especially true when you can’t find the right values or if they’re out of stock

Here are a few tips for getting the right value resistors if you’re having problems finding what you need:

  • You can use multiple resistors that add up the right value.
  • They don’t have to be the perfect Ohms value – close is usually fine. For example, if you couldn’t find a 4Ω resistor, a 4.2Ω would be fine (as long as it’s ok for handling the power across it).
  • You can use two resistors in parallel to get a lower value: for example, if you need an 8Ω one, you can use two 16Ω resistors in parallel to get 8Ω.

In my experience, not every electronic parts store carries what you need. You may need to get creative if you can’t find what you want.

Some of the most common Ohm rating resistors are values like 1Ω, 2Ω, 5Ω, 10Ω, and so forth which you can use to get fairly close to the value you need.

Example of miscellaneous power resistors different values in package on floor

You can use multiple value power resistors with speakers to change their impedance. To do so, you can mix and match as needed to get the right overall value.

Where to buy resistors for changing speaker impedance load

Power resistors aren’t something you’ll find everywhere. A few places I’ve found them available are at:

  • Fry’s Electronics (may be going out of business, however, so be aware).
  • Parts Express – great supplier of many types of audio & speaker parts including resistors.
  • Amazon, eBay, and other online sellers of miscellaneous parts.

That’s if you’re the USA, of course. For other countries, you’ll need to search a bit if you don’t already have a good source.

How much do power resistors for use with speakers cost?

Power resistors should be affordable. For example, I’ve paid as little as $1.99 for a pair and often have gotten sets of 2 or 4 for about $5 or so. This is for resistors with up to 25 watts power handing, in fact.


About the author

Marty is an experienced electrical, electronics, and embedded firmware design engineer passionate about audio and DIY. He worked professionally as an MECP-certified mobile installer for years before moving into the engineering field. Read more »

Your comments are welcome.
  1. Thanks for the info, very informative and easy to understand. My situation: I have an stereo (75W per 6.1 channel ~ 290 Watts in the specs) on which I can set the impedance to 4 or 8 ohms across the A and B output combinations, with the A outputs being a 6.1 setup.

    Off the B outputs I would like to install a multi-speaker splitter (up to 6 speaker sets) that requires (read the instructions after the purchase) that the attached speakers are a minimum of 8 ohms, unfortunately, I bought four sets of 4 ohm speakers to work off the splitter. The splitter does show the resulting impedance changes when 1, 2, 3, 4, 5 and 6 speaker sets are turned on with 8 ohm speakers.

    The calculations you provide in your article do a great job of ‘showing your work’ to get to each of those impedance results.

    My question: Can I install 40W 4 Ohm resistors in series on in left and right speaker inputs to the splitter or should the resistors be added to the output side of the splitter? With four sets of speakers going to four different areas of the house, it is likely that I will only ever have to sets of speakers on at a time.

    • Happy Friday, Steve. I’m flattered you found my information helpful & easy to understand as I certainly try!

      To give you the best possible answer in your particular situation (and the best sound and power to each speaker), if you could answer a few basic questions it would be super helpful:

      1. What is the brand & model of your stereo?
      2. What is the brand & model of the splitter?
      3. To be clear, you are saying you have a total of 8 (4 pair) 4Ω speakers you’d like to use on the “B” outputs, correct?

      I ask because in the case of using more speakers they’ll have to share the available power. If resistors are used, a fair amount power power will be lost as heat. To help you the most and possibly avoid that issue if you let me know items #1-3 that would be great. Thanks!

  2. Hi marty, please tell me i have tpa 3116 2.1 subwoofer system. Left and right channel power about 50w*2, unfortunately i have got two speaker of Lg but it ohms value about 2.7oms.. manufacture of tpa 3116 says minimum ohms value should be 4ohms speaker , so how could i joing above speaker to this system .. is 1ohm power resister is enough to adjust impediance value and how much power lose if i use 1ohm resester in series way

    • Hello Sameera. Realistically speaking, the 1Ω will probably work fine. That’s not much difference altogether so I would expect it to work out ok.

      So let’s assume the speaker impedance is around 2.7Ω. The power lost across the 1Ω series resistor would be 1Ω/(1Ω + 2.7Ω) = 0.27, or just a little over 25%. So at max power (50W RMS) you’d lose about 13.5W.

      Not all that bad, all thigs considered. (Ex.: using a 4Ω with a 4Ω speaker is a loss of 50%!)

      Best regards!

  3. Gear in my ‘use of discounted speakers I got an excellent price on’ =
    1) VHT Special 6w valve amp with 4Ω, 8Ω and 16Ω output sockets.
    2) Eminence 75w 10″ speaker [8Ω, 98.7 dB]
    3) Eminence 35w 12″ speaker [16Ω, 98dB]

    I’d like to use these 2 speakers in parallel. Ideally each speakers would have a similar volume or if unbalanced, with a slight emphasis on the 12″ 35w speaker.
    I’m thinking my options are:
    a) Wire in parallel ignoring the Ω mismatch ~ and use the 8Ω amplifier output to drive the (combined) 12Ω load, or;
    b) Wire in parallel with (i) the 12″ 16Ω speaker 1st in the chain and (ii) the 10″ 8Ω speaker second in the chain with an 8Ω resistor across it’s terminals.

    In the case of scenario (b), am I right thinking the combined load will be 8Ω, and that the 12″ 16Ω speaker driver will driven at ‘full’ power whereas the 10″ 8Ω speaker driver, hamstrung by the resistor, will run at ‘half’ power?

    Thanks Marty ~ and many thanks for sharing your knowledge and providing a safe space for us less knowledgeable to ask questions without getting a Gear Page-style battering.

    • Hi Monty. That’s some interesting equipment & speakers you’ve got. Let me address what you mentioned point by point:

      A) Wiring both speakers in parallel would give you around 5.33Ω, so you’d need to use the 4Ω speaker output terminal.
      B) This option is worse, and it doesn’t help and will actually cost you power. It will certainly work safely, but 1/2 of the power across the 8Ω speaker + 8Ω power resistor will be wasted as heat across the resistor (about 1.5W of the 3W applied to the 16Ω load). In a situation where there’s not much power available it’s not a good option.

      Unfortunately, there’s simply not a “perfect” way to do this, as connecting multiple speakers is tricky – especially when the impedances are mismatched. The most practical way, in this case, is to wire both in parallel (see #A above) for about ~5Ω.

      This will allow around 4.5W total power to be driven to them.
      • ~1.5W to the 16Ω speaker.
      • ~3W to the 8Ω one.

      The 16Ω will have 1/2 the power of the 8Ω one at the same amplifier output because it requires a higher output voltage for more power. But it’s the most practical way with the “least bad” compromise I think in this case.

      Best regards, and I totally get what you mean about forums and getting battered for asking questions! Thanks for your kinds words by the way. :)

  4. Marty, the receiver is a Yamaha HTR-5560, the switch is a Pyle PSLW6 and 4 sets (8 speakers) Dual Electronics LU43PB speakers.

    • Hello Steve. It was very helpful to get that info, but I need to know what you’re planning to connect to channel output set “A”, if you are.

      Best regards.

  5. Sorry about the delayed reply.
    Equipment List:
    1) Yamaha AV Receiver HTR-5560
    2) A-Speakers (Front and Rear): – Paradigm Mini Monitor 100 WATTS, 8 Ohm (4 matched speakers)
    3) A-Speaker (Center – Front): – No Front (Sony TV, Sony Sound Bar (as Center Front Speaker) and Sony Blu-Ray),
    3) A-Speaker (Center – Rear): – Paradigm CC-350 175 WATTS 8 Ohm
    4) B-Speakers: Pyle Splitter – PSLSW6 – with Dual (brand name) Speakers – LU43PW (4 sets/4 channels – 8 speakers)

    Hope this helps.

    • Hi Steve that helps quite a bit.

      Unfortunately, the 4Ω speakers and the Pyle speaker selector unit aren’t going to work well in this case. That’s because the Yamaha is like many other receivers in that it allows two options for the main speaker outputs for the left switch position:

      • 4Ω or higher for outputs “A” OR B, with up to 75W per speaker.
      • Using outputs A and B: 8Ω min each channel, with up to 37.5W available to A and B, each.

      So attempting to use 4Ω speakers – even just one pair – on the B outputs will drop the impedance the receiver sees below 4Ω because they’re connected in parallel internally. The Pyle includes some type of impedance protection but the documentation is poor so I can’t rely on it to be sure.

      To get this working you will need to add a speaker impedance adapter like this one set to “x2” (I think) between the receiver’s B outputs and the switch’s inputs. This will keep the B output speaker load high enough. Note that I cannot say with 100% certainty that the x2 setting is correct in this case because the Pyle documentation is not clear on its specs. “x4” would be safe to use however.

      This is a kind of a tricky situation because of having 4Ω speakers instead of 8Ω; also because they’ll have to share power with the set A speakers. Connecting any in series makes it even worse and you’ll end up with very small power to whatever set of B speakers are in use. In the best-case scenario, you would get just under 10W to each Dual speaker with all 4 pairs in use.

      Honestly I personally will recommend against keeping the Pyle as it’s just not a good choice. A better option which would have been to just use a small 6ch. amp connected to some outputs from the receiver. That would avoid these problems and having 25-50% or so less power available to the speakers oun ouput set B. Hopefully this helps & best regards.

      • Wow – what a breakdown! Thanks for the feedback, there is a lot there to digest and plenty of food for thought. I will dig further into your suggestions and will get back to you if I have any more questions. Thanks again. With regards, Steve.

      • Thanks again for the reply.

        Reading up on your suggestions, I am seeing that based on the search: ‘Six Channel Amplifer’ one can find ‘Top 10’ results like:

        Pyle (PTA62BT) 2018 Bluetooth Home Audio Amplifier
        Pyle (PTA62BT.5) Upgraded 2018 6-Channel Amplifier
        Pyle (PTA66BT) 6-Channel Amp

        There were other suggestions but the devices were either suited for marine use or were rack mount designs.

        They all seem to work well at eliminating the 4ohm/8ohm impedance dilemma and provide other features including Bluetooth as well as providing amplification independent of the amplifier’s output. So from this list, it’s a matter of picking the one with the features that suit my needs, or are there some hidden and unasked questions.

        Thanks for your time Marty.


        • Hi Steve. A marine amp is just a car amp with a coated PCB and sometimes some additional seals around connectors, etc. The drawback is you’ll need an AC-DC adapter to use it, but the upside is they’re so basic & simple to use. Also you can bridge channels on them (typically) which you can’t normally do on home stereo type amps.

          So yes basically it comes down to features and what you feel is best for you. I see you’ve been doing your “homework.” Best regards. :)

          EDIT: I forgot to mention that with it comes to brands like Pyle you need to be careful about the power ratings. Unfortunately, they’re often not accurate. The good news is that you can estimate the continuous/RMS ratings based on the fuse rating or power consumption specs.

          Car/marine amps from other manufacturers (Rockville, for example) often have good power specs.

          • Thanks again Marty, I will admit that this exchange has made me realize that there is more to putting a system together than I initially thought. Thanks for sharing your knowledge and insight. Back to the books for me.

            This is definitely a 5 Star production you’ve got going here.

            Have a great weekend!

          • So summing up, installing a remote external amp will solve the impedance issue I created buying a pure, unamplified splitter not to mention purchasing 4 ohm speakers. Now connecting the external amp would be done with RCA terminated cables. I have not run the 4 sets of speakers yet but could the external amp be installed about 30 feet away and connected with speaker grade wires that have been terminated with RCA plugs or is that a stretch?

          • > could the external amp be installed about 30 feet away and connected with speaker grade wires that have been terminated with RCA plugs

            By this assume you mean using speaker wire instead of a standard RCA cable? You’ll still need a line-level signal either from RCA output jacks or a line level adapter.

            However, you could run speaker wire connected to the speaker outputs and then use the line level converter near the external amp. That should work ok, and you don’t need large gauge wire. Small gauge wire would be fine for this since it’s not delivering power but rather being used just for a signal.

          • Or use the MAIN Output Jacks on the back of the receiver through a Home Theatre grade 50 ft RCA direct to the 6 Channel Amplifier.

  6. Hi Marty –

    Fantastic article.

    I have a question.
    Is there a formula that helps give the decibel drop by adding resistance?
    In my car audio system my front dash tweeters/speakers produce a very forward sound stage and the front door speakers house woofers with the rear doors having coax speakers.
    If I try to balance out the sound stage by fading to the rear I lose power to the front door woofers.
    I was thinking about adding resistors, in series, to the front dash speakers thus increasing the impedance and reducing their efficiency and volume.

    So if I have a set of 4ohm speakers, that have a sensitivity rating of 83db, and I add 4ohm resistors, now equaling an 8ohm load, what would be the estimated decibel reduction of the speakers?

    Thank you,

  7. hi marty, there’s some really great info here. i wish i understood all of it
    i have a pro-audio question, i bought a pair of jbl 4680a P.A. columns, each has 4- 10″ k110 8ohm woofers, and two 2402 (bullet) tweeters, all are 8 ohm. there is a crossover for the tweeters, 3102 is the model number. the wiring between the crossover and 10’s were disconnected. i can’t find a wiring
    info for this speaker. any idea how this went together?

    • Hello Kurt sorry I don’t info for that particular crossover without seeing it up close. It’s probably out there somewhere – maybe on an audio DIY forum or something similar. Best regards!

  8. Hi, I’m using a 400watt 2 channel amp for my motorcycle. I don’t know what kind of resistor I should use on my rca to speaker wires. The kit didn’t come with the rca to speaker harness like it should have and the company wants to charge me 100 for one.

    My amp details: Full range class D audio amplifier, spec’d at 200watts RMS per channel X2, (400w total) into 2-ohm load @ 14.4vdc.

    [Edited by Marty to combine comments]

    • Hi Cody. What is the brand & model number of the amp? That would help greatly so I can help you the most. If it’s just a matter of getting a signal to the RCA inputs on your amp from a speaker level connection, a decent line level converter will work fine.

      They’re about $12-$15 or so and include more than just basic resistors (I’m planning to explain all the details in an upcoming article). But I want to be sure I’m clear on what you’re working with in order to give you the best solution. Best regards.

      [EDIT: Just to clarify quickly, yep – some companies sell their own “converter” for use with their amp and unfortunately they often charge too much for it. But it’s usually not the only way to do it.]

  9. Hi – super helpful info. Appreciate if you have a moment to check how I might manage an impedance dilemma.
    I have a Yamaha RX-V685 with a 5.1 set up with Q Acoustics 3000 series, and I’d like to add some 4 ohm B&W Solid Ovale 100w as the rear speakers to make the setup 7.1. The Yamaha subwoofer is connected via Musiccast.
    I was planning to add a 4 ohm resistor to each Ovale, but in order to manage the volume discrepancy this will create, adjust the gain up for those speakers in the AVR settings. I was also wondering whether the YPOA might manage that automatically?
    Is this a workable and safe arrangement?

    • Hi Trevor. You can add 4Ω resistors if you like. The power to each speaker will be reduced by 1/2, but that amounts to a volume loss of only 3dB which is tiny. I’m not sure about the YPAO.

      Another option is the use a speaker impedance adapter like this one so the Yamaha will “see” an 8Ω load on each channel. You won’t lose any power to those speakers that way (the volume control is completely optional in this case). Best regards!

  10. Hi Marty,

    I have two 6ohm 100w speakers wired in parallel creating a 3ohm load on an amp that supports 125w @ 8ohms, 187.5 watts @ 6ohms and 250 watts @ 4 ohms. I was thinking of wiring a 3ohm resistor in series to get the load to 6 ohms but what wattage should the resistor be? 100w also?

    Thank you

    • Hi Chris. You could do that, but since the amp supports a 4 ohm load per channel then you’d be better off only adding a 1Ω in series with the two 6Ω speakers in parallel or a 2Ω resistor in series with each 6Ω speaker then connect those in parallel.

      Basically, the power rating you’ll need for a resistor (maximum rating) is:
      – 6 ohms total load (3Ω resistor in series): 93W (100W is the closest standard rating)
      – 4 ohms total load (1Ω resistor in series): 62.5#

      You don’t need a resistor with that much power handling if you’re only using moderate power. High-power resistors are harder to come by but you can use multiple ones in series as they share the power across them.

      If you’re planning to drive the speakers with a lot of power, it would be a lot better to use a speaker impedance adapter like this one and avoid those issues. That’s because using a resistor/resistors means that power will be wasted as heat across them. A speaker impedance adapter will let the amp see the correct impedance and you’ll get full power to the speakers.

      Best regards!

        • Hi Chris. You can actually use the 300W rated OSD SVC300 model you see here. It’s my fault for not being clear about that option for you. My apology!

          It’s also possible to be creative and use the 100W version, 1 per speaker output/channel, when acheiving a 6Ω total load. Just that the total cost (2 units used) would be a bit more in that case.

          If you’d like to know how to make the 100W version work just let me know; it’s not hard to do. Best regards!

  11. Hi Marty,

    I built a new bluetooth speaker trying to use old parts I had laying around. Including those parts were two 2-way systems with a passive crossover that used to run with a single tweeter and two 12ohm midrange speakers in parallel.

    Given the small enclosure size I chose to use only a single Midrange speaker and simply left one connection “open”. To my surprise it didn’t noticably mess up the tuning of the crossover, but I obviously lost a lot of power since the amp now reads a higher impedance than it used to with the 2 speakers in parallel.
    To compensate for the problem I now have the choice between replacing the “missing” speaker with a 12 Ohm resistor or buying two new 6 Ohm speakers to simulate two 12 ohm speakers in parallel.

    As 6 Ohms is not that common, I have had a hard time finding such speakers with appropriate power handling for a reasonable price.

    Do you think the second option using a resistor on the Crossover (instead of the amp directly) could damage components, mess up the sound or do me any good at all?

    It’s worth noting that the 2-way crossovers are connected to the left and right channel of a 2.1 amplifier, meaning they won’t have to handle truly low frequencies in the first place (just dividing midrange from really high frequencies here)

    A quick opinion would be highly appreciated.

    Best regards,

    • Hi there. The sound and crossover will be fine using resistors to compensate for the difference with whatever speakers you’d like to use vs the original 6Ω load on the woofer crossover output.

      There are two pretty good ways to deal with this:
      1. Connect a 2Ω power resistor in series with a 4Ω speaker in place of the 12Ω speaker.
      2. Connect a 24-25Ω power resistor in parallel with an 8Ω speaker in place of the 12Ω speaker.

      Of the two, I’d prefer #1 as the 4Ω speaker would receiver more power/voltage from the amplifier than an 8Ω speaker. You don’t mention what impedance the tweeter is so I’ll have to assume it’s 6Ω. Best regards.

      • Hi Marty,

        Thanks for the quick reply.
        What a great idea! I really haven’t thought of those options yet.

        It also means I won’t be getting around buying new woofers though, right?

        I tried adding a 15ohm resistor I had laying around in parallel to the 12 ohm speaker yesterday, which lowered the measured nominal impedance (DC) to 7,3 Ohms. But that’s still a bit to high I guess and once again it would result in lost power similiar to what you mentioned regarding your option 2…

        I forgot to mention the tweeter has 7 Ohms nominal impedance, which I assume was picked intentionally in order to send a bit more power into the woofer output(s) than to the tweeter.

        I will try your first option (#1) and get back to the topic as soon as I tried it out.
        Thanks a lot for the great advice!

        • Well, you’d lose less power across the 15Ω than you would a 12Ω because of the lower current. But that’s very little difference in that case.

          The 7Ω tweeter is pretty close so I don’t think that small difference matters either. Hopefully you get it all sorted soon you can start enjoying your music! :)

  12. Got a question kicker l7 2 ohm but once i wire it its either 4 ohm or 1 ohm my amplifier sweet spot is 2ohm. Its 1000 watt sub how can i bring it up to 2 ohms

    • Hi, you can’t really get *only* 2Ω unless you only use one voice coil. Otherwise, you’ll have wire it for 4Ω.

      • Hi, I am in for a reply as well. I have 2 subs making a 1.0 ohm load on my amp, but the amp will put out more at an even lower OHM rating. Something like 0.67 or even 0.5 In a perfect world, I would like my cake and to also eat it.

          • Single L7 15 dual voice coil 2ohm. Was told i could add resistors if wired at 1 ohm to bring it back up to 2 ohms

          • Hi, that’s true, you technically can, but the problem is that you’ll waste 1/2 the power available across the resistors as heat. You’d be better off using only one 2Ω voice coil or both in series for 4Ω.

  13. I’m working (volunteer) with a musical group’s club PA system. The system is shared by a couple groups. They use an older Yorkville powered mixer that will handle 4-ohms or a little less without issues. The Mains side has 2 8-ohm speakers hanging from the ceiling. No problem there. They are daisy-chained together (in Parallel) to make 4-ohms, which is working fine.

    The problem, I think, is the monitor channel. They want to daisy-chain 4 separate 8-ohm speaker systems on the stage floor. I’ve told them it’s not a good idea. They do it anyway. (I’m not there for every gig) Recently, the powered mixer failed. Now they’re using our spare powered mixer. I’ve told them to unplug one of the monitors.

    Since the failure, one of the guys bought a new powered mixer to donate to the cause. It’s got more power, has more input channels (but the same 4-ohm, 2-channel output) and cost more money. More power does not equal correct impedance.

    I’d like to get these 4 8-ohm daisy-chained monitor cabinets connected safely…4 ohms total should be OK. I’m thinking of making a resistor in a box with a ¼” jack on one side and a cord on the other side to plug into the back of the PA monitor channel.

    I think…each time you daisy-chain a speaker, it divides the resistance… So 1 speaker is 8-ohm, 2 speakers = 4-ohms, 3 speakers = 2 ohms, 4 speakers = 1 ohm. Is that about right?

    So, 1-ohm with an 8-ohm resistor in parallel? Is there a ready-made box I can buy to put in the chain? Maybe with a switch for different resistances?

    How do I fix this???? I’m thinking adding a 100 watt 8-ohm resistor in parallel would make it safe to use.

    Thanks for advice here.

    • Hello Thomas. To keep things clear, when we say “daisy chaining” it generally refers to connecting devices or equipment of some type. To be 100% specific I’ll refer to the connection type instead (series, parallel, series-parallel etc.).

      Yep, when connecting multiple speakers in parallel, the strong total Ohms load seen an amplifier will be lower than just one alone. If they’re all the same value (say 8Ω, for example), you can just divide the impedance of one by the nubmer of speakers in parallel.

      Therefore 8Ω/4 = 2Ω. 8Ω/3 = 2.67Ω, etc…

      You technically can add series power resistors to speakers to make the total Ohms load add up to a safe amount, but while easy to do it comes with a price: 1/2 of the power normally available to each speaker will be lost as heat across the resistor.

      An easier way that also allows you get get all the power available is to use a speaker impedance adapter like those built into a volume control. The amp(s) will see the correct Ohms load but the speakers will still get the amount of power available to them. (When using 4 speakers, each would receive the max. RMS/continuous power of that amp channel divided by 4.)

      Here’s an example of what I’m talking about:

      This example shows 2 speakers but you can usually set them up to be compatible with 4 also. Best regards!

  14. i got a bargain on a 16ohm high quality speaker that i plan to replace the 8ohm speaker in my 40w watt tube guitar amp. i will add a 16ohm resistor parallel with new speaker. does it mean the speaker will only get 20watts power and therefore less volume?

    EDIT: I see you said “tube amp”, so if it’s a transformer output type of amp then I see why adding a resistor in parallel for 8Ω total may be good.

    • Hi, unfortunately adding a resistor in parallel is a waste unless there’s a reason you need to do so. That would waste 1/2 the amps power as heat across the resistor.

      The 16Ω speaker will never get higher than 20W because the current is 1/2 that of an 8Ω speaker at the same output level from the amp. If at all possible, using two in parallel would give you the equivalent volume/power of a single 8Ω.

  15. Hi Marty
    I have a Panasonic SC-BTT785 Home Theatre System and the amp part of the system has now failed, i really like the tower speakers so wanted to reuse them and have checked and they are 3 ohm at the following, front two are 185 W per channel the rear two are 125 W per channel and the sub is 200 W per channel, centre speaker is going to be removed because the New Sony TV uses the screen as the centre speaker so will be using this. my thoughts are to buy a Sony STRDH790.CEK 7.2 Channel Dolby Atmos/DTS: X 4K HDR AV Receiver, checking the speaker loading on the sony unit is 6 to 16 ohm so i need to add a minimum of a 3 ohm wire wound resister but my question is if you think the above would work is what wattage resistor would i need to accommodate the above wattage on them speakers pls?
    Thanks Marty

    • Hi Karl. The power rating for the resistor depends on how much power you’re planning on driving the speakers with. In this case, 1/2 the power will be wasted as heat across the resistors.

      It would be a better idea in this case to use a speaker impedance adapter set to the 2×1 option as it will avoid that and still keep your new AV receiver safe. Have a look here in this article where I talk about that. You would use one per each speaker pair, and you can just ignore the volume control feature if it’s not needed.

      Best regards!

  16. Marty,
    Great write-up, and I am an Industrial Instrumentation and Controls Technician and wanted to share a with you and the others a few sources for anything electronic or machinery related for current or future projects. Websites listed below

    Hope these help you and the others.

  17. Marty,
    This is a car audio question. I have a dual voice coil 6″ 2 ohm subwoofer (don’t know wattage rating). I want to use an old Coustic 2 channel amp that I have laying around the house. It’s rated at 4 ohms stable to 2 ohms. It’s rated at 25 watts per channel. Is it safe to use it without adding 2 ohm resistors to make it a 4 ohm load on each coil. It seems like I would not gain much if anything by adding the resistors. Can I just use 25 watts to each coil, and maybe turn the gain down?

    • Hi Larry, to be clear, you *did* say the Coustic amp is rated to 2Ω? As you wrote, “rated at 4 ohms stable to 2 ohms.

      If it is stable to 2Ω per channel then yes you can simply wire one channel to each voice coil. If not, you’ll either need to 1) wire the voice coils in series for 4Ω, or 2) add a 2Ω power resistor in series with each, then one channel per coil.

      Option #2 will work safely of course, but 1/2 power per channel will be wasted as heat across the resistors. If the amp is bridgeable, however, it would be better to wire the VCs in series (4Ω load), then bridge the amp to power it that way.

      Best regards!

  18. Thanks for the quick reply. The manual dose read stable into 2 – ohm loads. I was hoping that I would be able to wire one channel to each voice coil, so, that’s great news and makes things so much easier.
    Thanks again!

  19. I have 3 pair of speakers on my desk which I use to compare the sound of the recordings I make. They are powered by a Crown Amp and Yamaha mixer and use a speaker switch to make my comparisons. My issue is 1 pair is rated at 83 DB while the other 2 are rated at 87. Can I or should I use resistors on the more efficient speakers so I don’t have to turn the volume way up when I use the 83 DB pair? If so how would you suggest I do this?

    • Hello Vince. What Ohms rating are the speakers and what is the min. Ohms rating for the amplifier you’ll use them with? That will help to know.

  20. Hi, I have a 2005 Toyota Camry with a JBL amplifier that is rated At 2 ohms. I have some JBL 6 x 9 speakers I want to use but they are rated at 3 ohms so the sound is very low. How can I bring the speakers ohms to 2 ohms with a resistor? If that’s not possible, can I bring the ohms to 4 ohms so then I could wire the pair of speakers in parallel to get a to bring the load to 2 ohms. Thank you
    Russell Griffin

    • Hi Russell. Adding resistance won’t produce more power or sound – it will produce less. If the amp is rated for 2Ω, that’s the *minimum* rating it can handle. If you add resistance, some power will be lost across the resistors.

      If you’re not getting enough sound it’s likely the amplifier doesn’t have sufficient power or the signal to the amp isn’t enough. The best thing to do would address that in order to get better sound. Best regards!

  21. Hi

    I have Helix M6 car amplifier which is running a 12″ Blam relax subwoofer which is rated at 2 ohms single voice coil.
    The amp is rated at 200watts rms @ 4ohms on a bridge channel.
    The bridge channel running the subwoofer is clipping.
    Which resistor could i add to the subwoofer to change the rating to 4ohms to match the amp?

    • Hi, buying a power resistor in this case is a bad idea. You would need a 100W rated 2Ω resistor. The problem is that 1/2 the amp’s output power will be wasted as heat across the resistor. That’s a lot of heat & temperature, so you’ll have to have heatsinks installed as well to handle it.

      It would be much better to get a 2Ω subwoofer to connect in series with the one you already have. That power wil be put to good use as acoustical power instead of being wasted as heat. Best regards!

  22. Hi there very interesting stuff, so my question is, I have a mono amp that requires a 4ohm load provided by two 8ohm units. So I managed to get replacement drivers but at 4ohm each, my under standing is to wire them in series will give me 8ohm or parallel 2ohms so it it better to add a 2ohm resistor to bring it up to 4ohm or an 8ohm to bring it down to 4ohm? Thank you

    • Hi Lee. While it will work, it’s not such a great idea when it comes to woofers. If you add a series 2Ω power resistor along with the 2Ω parallel speaker load (for 4Ω) total), 1/2 of the amp’s output power will be wasted as heat across the resistor.

      Alternatively, if you could get another two 4Ω drivers you could drive all for, wired for 4Ω, without wasting any power. If you wire your 2 speakers for an 8Ω load, you’ll also have 1/2 the power available to a 4Ω load.

      Hopefully that helps a bit!

      • Thank you so much, sadly I can’t add anymore drivers as there isn’t any more space.

        If I wired two speakers in series to make 8ohms then added a 8ohms resistor to bring it back down to 4ohms is that also a bad idea?

        Thank you it’s much appreciated

        • I understand, Lee. Honestly, you’re better off just leaving them wired in series for 8Ω. Wiring a resistor in parallel with them will only waste 1/2 the power as heat also.

          If you create a 4 Ohm load (by wiring an 8Ω resistor in parallel), sure it will produce the rated power at 4 Ohms, but remember that the speakers and resistor will split the amp power delivered. Therefore it would be pointless.

          The power delivered to the 8Ω (series) speaker load will not change.

  23. Kind of understood everything, but I have a question, I’m connecting two 4ohm speaker in series, effectively making them 2ohm, but I need one to be 4 ohm for the inline crossover to work, does adding a resistor still work even if connecting the two speaker to the same channel?

    • Hi, did you mean to write “in parallel” instead of “in series”? As they’ll add up to 8Ω if they’re in series.

      Are you trying to connect 2 speakers to the crossover or what specifically are you wishing to do? I’ll need a little bit more info.

      • Hi, Thanks for answering!
        Yes, I mean in parallel( sorry for the confusion), it’s a 2 3/4″ speaker 4ohm with its own in line passive crossover and a 4″x6″ speaker 4ohm, and I’m connecting them to a one channel amplifier, if I’m in the right, that will change the impedance of the speaker to 2 ohm, and I’m really trying to keep the passive crossover on the small speaker.
        I’ll be grateful for some help

        • Hi, so if I’m understanding correctly (and correct me if there’s a misunderstanding), you’d like to do the following:

          1. Wire the 2.75″ 4Ω and the 4×6″ 4Ω speaker in parallel but keep a 4Ω total load.
          2. Use the crossover on the 2.75″ speaker.

          You can definitely do that! There are two ways in fact, whichever works out better for you:

          A. Wire a 2 Ohm power resistor to the positive (+) output side of the amp, then connect these in parallel after the resistor:
          • 4×6″ speaker
          • crossover + 2.75″ speaker wired together
          ^ This will result in 2Ω + 1/(1/4Ω + 1/4Ω) = 2Ω + 2Ω = 4Ω total at the amp.

          B. Wire a 4 Ohm power resistor in series with the 4×6″ speaker. Wire a 4 Ohm resistor in series before the crossover and then the 2.75″ speaker. Then each resistor + speaker/crossover series will be wired in parallel, giving 8Ω || 8Ω = 4Ω total.

          Electrically, both will be the same but personally if it were me I’d probably go with option #A because it keeps things simple. If you buy multiple 2Ω resistors, you can always use them later for projects where you need 1Ω, 4Ω, 6Ω, 8Ω…etc. They’re very useful.

          Hopefully this is clear. If not, reach out to me via my Contact page (see the top menu) and I can share a diagram or more details. Both 2Ω and 4Ω power resistors are usually cheap and not hard to find.

          Best regards. :)

          • Yes! Exactly.
            Thanks so much for the help, concise and very easy to understand, you’re the best!
            Many thanks again.

  24. Hi Marty. Great, informative article. Very clear and easy to understand.
    I’ve got an old tube amplifier rated at 25W, putting out 16 ohms, to a pair of 16 ohm rated speakers. I want to add a pair of tweeters to my setup. I just purchased a crossover. The new tweeters that I just bought are rated at 8 ohms. Am I correct in saying that I need to add an 8 ohm, 25 Watt chassis or wire wound resistor to each speaker feed?
    Many thanks for your help.

    • Hi Dave. Sorry for the delayed response – I seem to be having comment notification problems.

      The crossover you have won’t work because (I’m assuming) it’s designed for 8Ω. If you add an 8Ω resistor with either before or after the 8Ω rated crossover, you’ve changed how it behaves.

      In this case you’d want to add the 8Ω in series with the tweeter then use a crossover/ series capacitor suitable for 16Ω. For example, if the high-pass frequency is 3.5KHz, that would be around 2.8 microFarad for a 16Ω load.

      You can use my crossover calculator here if you need to check values:

      Best regards.

        • Hi there. You can use that, but you’ll have no control over the crossover frequency, so there’s no guarantee (unlike using a capacitor in series) what kind of sound you’ll get. The cutoff frequency isn’t even listed, I noticed.

          So it’s up to you as to which you’d rather use. Personally I wouldn’t use it it, but it may work out ok for your. Best regards.

  25. My old Chevy has a 10Ω speaker that’s gone dead and it’s not really worth buying a $70 repro for an AM radio. Can I really just use a 4Ω garage sale speaker and a 4-6Ω resistor?

    • Hi, yes you can just add series resistors if you like. 1 watt to 5 watt rated should be fine.

      If you want to get a better radio using an under-dash installation kit would make it fairly easy. (I’ve used those a lot on tractors, big rigs, and older trucks & cars).

      Best regards!

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