Resistor Tolerance in Speaker Crossovers

amplifiers, receivers and loudspeakers
jdjohn
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Resistor Tolerance in Speaker Crossovers

Post by jdjohn » 19 Jul 2019 04:08

I'm updating the crossover components in a pair of vintage KLH Model Twenty speakers. These are 2-way speakers with a 3-way switch for HF level. The OEM stock stone resistors are within their stated 10% tolerance, but since I'm replacing the capacitors already, should I replace the three resistors as well with newer ones at tighter tolerances (e.g., 1 or 2% tolerance)?

georgesgiralt
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Re: Resistor Tolerance in Speaker Crossovers

Post by georgesgiralt » 19 Jul 2019 08:08

Hello
Why are you replacing components ? Are they dead ? Do you experience problems ?
I often repair tube radios dating from the early 50's or 60's. Apart for high power resistors in the power supply having heated a lot, I rarely replace a resistor. (and it is in 99% of the case because of mechanical damage ).
The same applies for condensers. They only suffer in high power supply because they do a hard work smoothing the voltage. And even there, quality is so good now that not all of them are dead.
So if it's not broken, do not fix it ....
Just my 2 ¢

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Re: Resistor Tolerance in Speaker Crossovers

Post by Solist » 19 Jul 2019 14:34

Not trying to deviate the topic, but should not the resistors in the early tube radios be problematic since they are carbon and they radically shift in value as they age? Especially with tube gear?

I am a complete novice when it comes to electronics, just wondering.

Judging from my amp service manual (made in the late 60s), 10 and 5% carbon resistors is what they had in the 60s, so they used that. 5% were probably used where they mattered more, although they seem to cost the same, so I wonder.
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jdjohn
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Re: Resistor Tolerance in Speaker Crossovers

Post by jdjohn » 19 Jul 2019 15:36

georgesgiralt wrote:
19 Jul 2019 08:08
Hello
Why are you replacing components ? Are they dead ? Do you experience problems ?
I often repair tube radios dating from the early 50's or 60's. Apart for high power resistors in the power supply having heated a lot, I rarely replace a resistor. (and it is in 99% of the case because of mechanical damage ).
The same applies for condensers. They only suffer in high power supply because they do a hard work smoothing the voltage. And even there, quality is so good now that not all of them are dead.
So if it's not broken, do not fix it ....
Just my 2 ¢
Hi George,

These are KLH Model Twenty speakers from the 60s. I'm updating the capacitors to metalized polypropylene since the originals are so badly out of spec now. I've also read that these particular old caps can leak and/or ignite :shock: So while I'm in there, also considering replacing the resistors.

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Re: Resistor Tolerance in Speaker Crossovers

Post by theclosetguy » 21 Jul 2019 02:08

So many misconceptions concerning crossover components compared to tube amp components. One is low voltage and one is high voltage. I have yet to find a cap or resistor in a crossover network that is out of original spec's. Since they are not subject to the high voltage of powered electronics they do not take the same abuse. The caps are usually well with in the 20% tolerance and so are the carbon comp. resistors. By changing capacitor type and now introducing tighter tolerance in resistors what happens is the sound of the speakers change.
Ignight. hahahahaha. That's an absolute bunch of B.S. Does anyone even know what a leaking capacitor is?
If the caps are more than 20% out of range they are old and should be replaced with the same exact type and spec cap. 100volt is more than enough.
Stop believing 90% of the B.S. out there and just enjoy the KLH speakers.
Mike M

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Re: Resistor Tolerance in Speaker Crossovers

Post by ]eep » 21 Jul 2019 04:08

I have no idea what ignight means, but it sounds like a dark secret.

And yes, there's a lot of BS out there. Especially from trained electronics 'engineers' who do not use their ears. You know, the scientists who always know better. Because they had to pay lots of money for their education and are still having a s#i77y life because of study debt. And trying to get one by swarming fora to make others feel dumb by laughing at them instead of giving usefull answers. (sorry for that rant but sometimes being too polite doesn't get the point across).

Blowing up a capacitor in a speaker crossover would be very, very hard. So don't sweat it. If you blow a resistor you will hear the difference. Or better: nothing. Often if the resistor turned brown there's a blown unit too.

But... The components in a speaker filter, and the layout of a speaker filter makes ALL the difference. It can literally make or break a speakers sound. While electrically they don't make ANY difference at all, sonically the difference can be huge.

Any component that's in the signal path will change the sound signature. ESPECIALLY capacitors. So do resistors. And coils, not only wire gauge but also how it's wound. And preferably no magnetic core to keep cost down.

While wirewound resistors are fine and hardly ever break/burn they are not the best for sound. But in your speakers, no problem at all. Usually for a tweeter 5W is fine.

As for capacitors, if it drifts a bit, that is no problem at all. You can't hear the difference if it crosses over a bit higher or lower since it's doesn't change peak level. But it does change the quality of the sound going to your tweeter. How much? That's hard to say for your speakers. Use good MKP's. There's enough information on the internet which ones sound good.

Lately I've bought several speakers that had really simple crossovers. Not only were the components really cheap (10uF elco's! Ugh) but also really mindless serial production boards. Or typical 'play it safe we don't want returns from idiots with 500W amps'. My last pair went from 'there's potential but, ouch, such harsh sound' to absolutely amazing. Just by replacing 2 caps and removing 2 coils. 5 mins work soldering and cost me like €12.

It's really worth looking in to in more detail. But I can't share years of experience in typing 1 post.

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Re: Resistor Tolerance in Speaker Crossovers

Post by theclosetguy » 21 Jul 2019 15:36

sorry ignite. Catch fire, explode, blow up.
mike m

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Re: Resistor Tolerance in Speaker Crossovers

Post by jdjohn » 21 Jul 2019 16:45

I've only done a handful of speaker re-caps at this point, but each time I've been able to hear improvements. Swapping from electrolytics to film or MKP caps seems to make the biggest difference. In the case of these KLH (and a pair of AR-2ax about a year ago), there a multi-section cardboard caps in place. I've gone with Solens for the replacements - not too expensive, but not the absolute cheapest either. The heft of the cabinets in these old acoustic suspension speakers is well worth preserving, so updating the passive components is money well spent IMO.

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Re: Resistor Tolerance in Speaker Crossovers

Post by Sunwire » 21 Jul 2019 19:46

If you just want them to work, don't worry about it.
If you want the best sound, use high precision parts and match each pair of corresponding parts as closely as possible. That's what the best speaker manufacturers do for their best speakers.
It's not practical for high volume production at low profit margins, but you're only working on one pair of speakers and don't have to worry about production quotas and.profit margins.

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Re: Resistor Tolerance in Speaker Crossovers

Post by aardvarkash10 » 21 Jul 2019 20:53

Sunwire wrote:
21 Jul 2019 19:46
If you just want them to work, don't worry about it...It's not practical for high volume production at low profit margins, but you're only working on one pair of speakers and don't have to worry about production quotas and.profit margins.
Good advice. 10% is close enough since your caps are unlikely to be more than that anyway.

If you wanted to get all super-matchy and technical, you could "blueprint" it by measuring the signals (in and out) and making the various minute adjustments to the components to get the crossover frequencies exactly to spec.

But in reality, your ears are not good enough to hear the difference.

No-one's are.

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Re: Resistor Tolerance in Speaker Crossovers

Post by theclosetguy » 22 Jul 2019 16:15

I have a pair of Radio Shack Minimus 7 Bookshelf speakers. They sounded pretty good with my Marantz 1060 consol amp as well as the Sonos Connect Amp I used in my backyard. Left them alone for 30 years until I found a few articles on improving the crossovers for these. Since they all recommend the same configuration I decided to give it a try. Completely change how they sounded. They still sounded good with the Marantz, although the mids and highs were a bit more pronounced. On the other hand the digital Sonos amp now sounded like crap. Highs were just to harsh and the lows had flattened out.
Not all changes will sound good.
Mike M

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Re: Resistor Tolerance in Speaker Crossovers

Post by jdjohn » 22 Jul 2019 21:51

Mike, you are right...not all changes sound good. I just did a quick read on those RS Minimus 7, and it sounds like those can be nice little gems.

One good thing about these KLH Model 20 is that there's a high-frequency output (tweeter) 3-way switch on the back for Low, Normal, High, so that should help tame them or boost them as necessary. These speakers have 10" woofers, so hoping for tighter bass on those with new caps. I will be re-sealing the cloth surrounds on the woofers as well, and also putting on fresh gaskets. I might even install some simple bracing inside, and replace the fiberglass filler with a polyfill, and experiment with how much filler to use.

Which receiver/amp to pair them with will require some thought. These are 4-ohm speakers, so I can't just use any old receiver with them to get the best result, particularly to control the bass.

It will be interesting to see how they turn out, but my expectations are really not that high. I just wanted to breathe some new life into them, and preserve the vintage look. These will likely go to a friend or family member.

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Re: Resistor Tolerance in Speaker Crossovers

Post by D Carroll » 25 Jul 2019 05:14

I would absolutely replace stock NPE caps with MPPs or film (depending on size). You can get audio grade noninductive 2% and 1% resistors on this page at PartsExpress: https://www.parts-express.com/cat/audio ... istors/301. I have used the house brand Dayton components many times in my nearly 20 years as an amateur loudspeaker builder. The Daytons are dirt cheap, and even the Jantzens are not very expensive - a bit over 3 bucks each. If you are spending the money to replace the caps, spend a few bucks more and do the resistors too.

As to sound change, a few years ago I got rid of the probably 30 year old 10 uF NPEs in the Dynaco A35s my dad used to own. I don't think it changed the sound, but I don't trust NPEs that old.

I am new to the board so IDNK what people know about Parts Express. I have been dealing with PE since early 2000 with not a single bad experience to report.

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Re: Resistor Tolerance in Speaker Crossovers

Post by jdjohn » 25 Jul 2019 15:06

Hi DC,

I actually used PE for this order :D I went with Solen caps, and for the resistors, I had to split between Daytons and Mills to get the different values I need.

I agree they do have great service =D>

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Re: Resistor Tolerance in Speaker Crossovers

Post by D Carroll » 25 Jul 2019 20:37

JD: I have used the Dayton MPP caps a lot and found them to be very good. My avatar is one of a pair of speakers I designed and made for our son to take to college back in 2005, using Dayton RSS series drivers - 7" aluminum woofer, and aluminum tweeter - and all Dayton xo parts. I named them The Advocates, in honor of his success in high school mock trial. They are still going strong in his and his wife's home.

If you really wanna be bored, I can post a pic of the xo, which is messy looking but works fine.

The DIY gallery here has pics of my MTM floorstanders and RSS 12" sub.

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