Another new KLH Five owner with questions

[Brad1234]

Well, in my humble opinion, the AR 3a's are the superior sounding  speaker, the bass goes so low and powerful it actually hurts sometimes, like ur body reacting to an imminent threat instinctually, and I am very used to loud bass. It's just different with these AR's. But the AR's sound best up close, they don't project into living room as well as other speakers (cerwin vegas, JBLs). The mid and treble on the AR's are also much lower sounding than other speakers, which is great up close on couch, but if u crank it u hear the difference. I am wondering if my AR mids may need rebuilding/replacement w rebuilt ones? Will need to save $ for that later. So, in summary, I think my AR's are better overall sounding speakers.
 

My KLH 5's are well sealed with the Vintage AR doping sealant, so they are very tightly sealed.

But the real battle is between my AR's and my JBL L100's first gen inline speakers. They are all around great sounding and project some seriously loud, clear sound long distances. But I do prefer AR/KLH acoustic suspension for bass response over JBL bass reflex. 

[jessiAV]

On 3/11/2022 at 12:31 PM, JKent said:

The pics above, the first had no SN but its mate was SN 12470.  The 2nd pic is SN 06845. Do they resemble the 1st or 2nd?

  Kent, Okay, today I removed one of my pc boards for oxide removal (xo's are low voltage, high current circuits, so their connections should be kept quite clean), and I see now that they are identical to your #112470. So that indicates that most of the newer Fives' PCB's probably had full soldered traces. One mystery solved, maybe?

[Mot]

@JKent et.al, I am preparing to recap a pair of Model Fives.  They are the later variety with the PCB.  My question is regarding the "+3 +4 uf" capacitor.  I am assuming that the two leads on one end are joined and soldered.  How do you handle the soldering of the other two leads... where do you solder the 3 uf lead and where do you solder the 4 uf lead?  Hope this makes sense.  Here is a pic of the cap in question.  Many, many thanks in advance!

 

[JKent]

Hey Mot

The double capacitor as you said has a single lead at one end and 2 leads at the other. You "make" a new one by combining one 3uF and one 4uF as you described. I assume your question is "which lead is 3 and which lead is 4?"

Below is a photo of a stripped board where I marked all the values. It's rotated compared to yours but on yours, from left to right the first cap is the 16uF, then the 3uF, then the 4uF.

Kent

PS: That full-size pic may be a little hard to read. 2nd one is a close-up with values clearly marked

 

[RoyC]

Hi Kent,

I don't have a reference board to look at, but it appears you have the separate 3uf and 4uf leads reversed relative to Mot's photo.

Roy

[JKent]

Yes, it does look that way and I don't have a reference board here either. But I have lots of pictures. I think I've only done 3 or 4 pair of Fives with the PCB XO but all of them were lined up as I described: 16 on the outside, then 3 then 4. Actually I don't really understand the question so Mot, maybe you can chime in here. I'm pretty sure the 5uF and 4uF leads are marked as such, so just use that as your guide.

Kent

[Mot]

Hello Kent and Roy.  Thank you both for your help!

Kent, you are correct, I am trying to determine which lead is 3uf and which is 4uf.  I'm not sure if it will be helpful, but here is a close-up photo of the cap in question.  

I'm starting to wonder if it would matter much if these leads were inadvertently switched.

Thanks again. Tom 

[JKent]

1 hour ago, Mot said:

I'm starting to wonder if it would matter much if these leads were inadvertently switched

Probably not.

btw, Roy and I have been discussing, for years, whether the 5w resistors should be replaced. The latest consensus is this: The 5 ohm/ 5 watt resistor in the woofer circuit is a critical design flaw. I have been replacing all of the 5w resistors with 10w but Roy analyzed the circuit and concluded it's best to replace it with TWO 10 ohm 10 watt resistors in parallel, giving you a 20 watt 5 ohm resistor. That gets crowded on the PCB version especially but the good news is Roy says you don't have to replace the others UNLESS they are Rockwood brand. If you want to be real safe you can replace the 15 ohm resistor in the mid circuit. I'm thinking 10w is enough.

Hoping Roy will comment on this.

Kent

[RoyC]

If the 3uf and 4uf leads are marked as such, Mot's photo shows them to be labeled differently than those in Kent's photo. Mot, if you can show us the reverse side of the board and circle the solder points of the cap leads we are discussing, along with those of the 15 and 10 ohm ohm resistors, I can probably tell you for sure.

Switching the caps will make a relatively small difference at the level control settings.

Roy

 

[RoyC]

22 hours ago, JKent said:

Probably not.

btw, Roy and I have been discussing, for years, whether the 5w resistors should be replaced. The latest consensus is this: The 5 ohm/ 5 watt resistor in the woofer circuit is a critical design flaw. I have been replacing all of the 5w resistors with 10w but Roy analyzed the circuit and concluded it's best to replace it with TWO 10 ohm 10 watt resistors in parallel, giving you a 20 watt 5 ohm resistor. That gets crowded on the PCB version especially but the good news is Roy says you don't have to replace the others UNLESS they are Rockwood brand. If you want to be real safe you can replace the 15 ohm resistor in the mid circuit. I'm thinking 10w is enough.

Hoping Roy will comment on this.

Kent

As I've read Kent's resistor replacement recommendations over the past few years I realized I have not actually seen many bad resistors on KLH 5 boards, so I have not been replacing them if they measure satisfactorily. Upon recently finding a burned out 5 ohm/5 watt specimen I contacted Kent to compare notes. He concurred that the crispy resistors he had seen before was the 5 ohm/5 watt one. I decided to take a close look at the schematic, and It turns out that this is the only KLH 5 resistor in the woofer circuit. With a power rating of only 5 watts it is really quite small to be in this location. A replacement with a 15 to 20 watt rating would not be unreasonable if the speakers are going to see any kind of hard use. On the other hand, given the type of use most of them are seeing these days, I'm sure the 10 and 12 watt replacements Kent has used in the past are holding up just fine.

The 15 ohm resistors in the mid and tweeter circuits respectively are 7 watters, and the others (5 watts) are in the tweeter circuit. I don't have a problem with them unless the speakers are going to frequently be used at high volume levels, at which point a prudent upgrade could be made to the mid's 15 ohm resistor (as Kent mentioned above). EDIT: It appears the 15 ohm resistors were reduced to 5 watts for the later PCB board. The earlier point to point wired boards (6 of which I have worked on in the past month or so) had the 7 watt version. Either way, I still would not be too concerned about it.

Coincidentally, as Kent and I were discussing the above, I found a crumbling "Rockwood" 10 watt resistor in a KLH 23. It was identical to malfunctioning 10 watt Rockwood resistors I have found a number of times in Kloss era Advent Loudspeakers. Interestingly, other brands such as Colber, also found in Advents, seem to have held up very well. When poking around inside KLH speakers, it would be prudent to look for these as well. They often do not appear to be burned, despite being nonfunctional and/or falling apart.

It bears mentioning once again...Whether it be pertaining to resistors or capacitors, anyone planning to work on old speakers should invest in a basic LCR meter. Mot's dual cap question could potentially be answered by simply measuring it with an inexpensive meter. (On the other hand, KLH caps are typically so crappy, who knows...)

Roy

[jessiAV]

Kent's diagram regarding the orientation of the 3/4 uf cap is correct. Maybe this picture of the PCB that I scribbled on will show why?

[jessiAV]

Additionally, here is an edited photo showing the caps that are directly in the signal path (in series) with their associated drivers when the rear output switches are in their 'normal' positions.  Some Five owners may wish to use better quality capacitors in these locations, where they have a greater effect on sound quality? The yellow rectangles show both caps that are in series with the tweeter, and the green rectangle shows the midranges capacitor. 

      The iron core (with the metal strap over coil) inductors are also in the signal path, one to the woofer and one to the midranges.

[JKent]

Thanks again Jessi. I would just add that you should ALWAYS replace those black and red caps. CSP friend Professor John O'Hanlon explained years ago why they are especially prone to leakage: The black is PVC and the red ends are something else and they expand and contract at different rates and temps. They are often out of spec, usually waaay out. Sometimes shorted and I've seen more than a couple that had completely exploded.

 

Edited June 18, 2022 by JKent

[Mot]

Here is the underside of my crossover.  I have circled the positions of the 4uf and 3uf soldered leads. 

[jessiAV]

Thanks Kent.

   Yes, I plan to replace those red electrolytic's with equivalent Mundorf E-caps, other than the tweeter caps which may be noticeably improved by using some special Russian oil caps I've been hording for a special application such as this. And as you may well have guessed, these original caps have drifted up in value, the 4uf's now reading about 6uf, the 16 around 22uf.  Of course, that means too much lower frequency energy feeding into the mids and tweeters. That is not good, although it's very typical for un-restored Vintage speakers..

       Also, I plan on following your and Roy C's recommendation to replace the 5 ohm woofer resistor with a 10 watt. That should be adequate power handling for my use, and these Fives will be staying with me for a long time.

   BTW, Mundorf's are offered by both Parts Connexion in Canada and Soniccraft here in the USA. Do you have a opinion as to which source is better?

 

   

[RoyC]

20 hours ago, Mot said:

Here is the underside of my crossover.  I have circled the positions of the 4uf and 3uf soldered leads.

Thanks, Mot! It appears your dual 3/4 cap was either installed incorrectly at the factory, or the "follow the label" theory may not be correct. The KLH 5 schematic confirms the diagram posted by Kent to be correct, so your 4uf cap and 3uf cap should be reversed relative to your photo(s).

If there is one constant when it comes to KLH speakers, it is the awful red and black capacitors. I have worked on 3 pairs of KLH 5's, a pair of KLH 17's and a pair of KLH 23's in the past 2 months, and only 6 out of the 44 capacitors measured anywhere near their proper values...and when they did, ESR was crazy high. I often wonder if some of these caps were within spec when they were new.

jessi...I don't subscribe to the pricey Mundorf world, but Madisound is another good source for those: https://www.madisoundspeakerstore.com/index.php?p=home

Madisound has an excellent variety of other brands as well, with their electrolytic and film MDL brand caps being a particularly good/high quality value.

Roy

 

[Mot]

17 minutes ago, RoyC said:

Thanks, Mot! It appears that your dual 3/4 cap was either installed incorrectly at the factory, or the "follow the label" theory may not be correct. The KLH 5 schematic confirms the diagram posted by Kent to be correct, so your 4uf cap and 3uf cap should be reversed relative to your photo(s).

If there is one constant when it comes to KLH speakers, it is the awful red and black capacitors. I have worked on 3 pairs of KLH 5's, a pair of KLH 17's and a pair of KLH 23's in the past 2 months, and 6 out of the 44 capacitors measured anywhere near their proper values...and when they did, ESR was crazy high. I often wonder if some of these caps were within spec when they were new.

jessi...I don't subscribe to the pricey Mundorf world, but Madisound is another good source for those. https://www.madisoundspeakerstore.com/m.d.l.-capacitors-page-5 Madisound has an excellent variety of other brands as well, with their electrolytic and film MDL brand caps being a particularly good/high quality value.

Roy

 

Thanks everyone.  I'll follow the diagram posted by Kent.

@jessiAV, I hope I didn't hijack your thread...

[jessiAV]

No worries Mot. We all here to share what we've learned and to ask questions.

[jessiAV]

  Thank you Roy, for the Madisound link. You are so right, Mundorf's upper tier caps are crazy expensive, are they not?  Mundorf's E caps (bi-polar electrolytic) sold at the  Partsconnexion link that Kent posted above (on march 10) are similarly priced to Madisound's MDl PP and 'lytic caps, and I was planning on fitting those.

       When I've worked on the crossover's to get the driver levels correct, I will post my impressions of the Fives here. I will say now however, that as your magic sealant dries the bass just gets better and better. Loving it!

[jessiAV]

While renewing the caps on one of my KLH Five boards, I thought it might be informative to measure the ESR and capacitance of both the old Temple caps and the new Mundorf E-caps . Here are their results:

   Temple: 25 uf indicated:                     now  40.5uf               .34 ohms

   Temple dual cap:  4/4uf indicated:    now  6.9 and 7.2uf    both 2.1 ohms

   Temple dual cap:  4/3uf indicated:    now  7.5 /8.4uf  and  1.9/2.2 ohms respectively

 

    Mundorf:  4uf indicated (5% tolerance): Cap #1 measures 4.9uf  .33 ohms

                                                                       Cap #2 measures 4.9uf  .32 ohms

                                                                       Cap #3 measures 5.0uf  .35 ohms

                                                                       Cap #4 measures 5.0uf  .31 ohms

Mundorf:  15uf indicated (5% tolerance):   Cap #1 measures 17.5uf  .37 ohms

                                                                       Cap #2 measures 17.5uf .48 ohms

Mundorf:  22uf indicated (5% tolerance):   Cap #1 measures 25.1uf   .3 ohms

                                                                       Cap #2 measures 25uf   .32 ohms

Mundorf:  2.7uf indicated (5% tolerance):  Cap #1 measures   3.4uf   .6 ohms

                                                                       Cap #2 measures  3.4uf  .61 ohms

     Okay yes, maybe this is TMI?  ::laughing::

[JKent]

I'm a little surprised by the Mundorfs. I've found modern caps to be pretty much spot on. +25% on a 5% "premium" capacitor seems unacceptable to me. Am I missing something?

[RoyC]

jessi,

Does your capacitor meter have a frequency setting? If these were measured at the rated 1000hz, I agree with Kent. I have a feeling, however, your meter is measuring at a much lower frequency. Electrolytic crossover capacitors behave differently than film caps at higher and lower frequencies, which is the primary reason for any sonic differences.

Roy

[jessiAV]

You are right. I was sleepy when I ran these measurements and used a component tester running at 100k, which is the industry standard. Dumb me..  

   Here are a few tests on the Mundorf E-caps run at 820 hz:

   3.9uf indicated:     4.3uf

   22uf  indicated:   23.5uf

   15uf  indicated:    16.5uf

 

  I also think I see a partial reason the 5 ohm, 5 watt resistor fails.  When the original Temple drifts to 40uf, the power running through it substantially increases if I'm not mistaken.

Edited May 3, 2022 by jessiAV
typo

[Brad1234]

On a related note, and I know there probably is no real answer to this, but is/are there recommended capacitor brand(s) for recapping "vintage" speakers?  I have used Auden and Jantzen Polypropylene caps from Parts express in several recaps and have been pretty happy with them. I tried a Auden plus Intertechnik foil 0.33 uF foil bypass cap that cost like $15, and was very disappointed with the sound in my Dynaco A25's, tweeter was waaaayy to harsh. I removed and went with Auden PP .33 cap and got much better sound quality. I think with the vintage speakers, the foil caps are overkill and makes them sound to harsh?  Am I right about this assumption?  

[jessiAV]

Good question Brad.  Since the E-caps did not work well (too bright surprisingly) with my Five's crossover, I'd be very grateful to learn what would be a good cap in this application. Kent would be a great adviser if he was able to evaluate the crossovers he renews connected when to the speakers, but it seems he hasn't had that opportunity.

     As it's clear I am not a passive filter expert,  I was wondering about the cap across my KLH's woofer.  Of course it's part of the LC filter, but does it also help damp the back EMF of the woofer's coil (at resonance?) as well?  If so, it would be a clever way of smoothing the woofer's response.  😀