KLH-1 Score

[Goldjazz]

Congrats, hang onto them they are one of the best keep secrets in vintage audio...well not anymore after this thread ha. Try to track down a KLH-1 A.B.C it really improves the bottom end, i did some frequency plots to confirm this. The sound from them fills the room nicely, and because they are so slim, placement within the room is easy.

I just joined the KLH-1 club!!! I stopped by a local estate sale that had several hundred LPs. A couple of guys were talking about the KLH speakers but didn't know anything about them. I got them for a steal. I went back a couple hours later to see if I could find the ABC but it was nowhere to be found.

I have been playing them all afternoon with my Yamaha CR-600 and YP-701 turntable and they sound glorious! I knew they were good when I picked them up!!! I am thinking of doing a recap per this thread. What has me thinking is how might the crossover be changed to deal with not having the ABC. The KLH-3s use an ABC but not the KLH-4s, maybe there was a change in the crossover that compensated for not having the ABC...?

Now to make some stands for them and figure out the best location for them!

 

[comish4]

Yes the KLH speakers were fantastic sold and owned a pair of the 1s for decades still have a set of 2 now. The ABC was used also for help in placement. The stands were a big factor in the 1s and 2s.

 

[Roger Gorke]

Congrats, hang onto them they are one of the best keep secrets in vintage audio...well not anymore after this thread ha. Try to track down a KLH-1 A.B.C it really improves the bottom end, i did some frequency plots to confirm this. The sound from them fills the room nicely, and because they are so slim, placement within the room is easy.

I see an ABC for the KLH-2, do you think that would work ok? The KLH-1 ABC has a pot on the back next to the power input jack that isn't on the KLH-2. What's the pot do?

 

[Roger Gorke]

So, I think it might be a good idea to work on this crossover circuit...LOL!

Already replacing parts...

 

[RxDx]

Yikes. Enthusiastic listening

 

[Roger Gorke]

Yikes. Enthusiastic listening

Exactly, I believe this is what they (KLH) means when they said using the speakers w/o the ABC can damage the speakers. It appears that it could have specifically damages the crossover. The traces on the back were pretty fried as well. I had to redo the traces with the extra lead lengths.

I replaced the two resistors and put in a new 10uf cap. Amazing how speakers can perform when their crossovers aren't fried.

I will be redoing the entire crossover for both speakers with high quality Dayton caps. I also realized that I have two 100uf Erse Pulse X caps, they are ginormous at nearly 2" in diameter.

 

[RxDx]

I'm not sure exactly how all that works- pulling bass response out of drivers
ordinarily not capable of it. Reminds me of the Bose 901 series. So it doesn't
make sense that running w/o the computer could cause damage.

Then again, maybe it's at least partly about limiting overdriving the system to
get that bass.

 

[Roger Gorke]

Update: I have an ABC on the way that should be here today. I also found a power supply on amazon that is 12vac @ 1A and 8 W, so that should be plenty. It is a KLH2 ABC but in what I have obsessively researched the past several days, the different bass response between the KLH1, 2, &3 that uses the ABC looks to be due to the crossover. The KLH1 crossover has 2-25uf caps for the woofers. The KLH2 crossover has 2-50uf caps. This is unless I am misunderstanding the crossover circuit.

How are you guys connecting the ABC and the speaker cables to the receiver/amp? My Yamaha CR-600 has spring clip connectors. My current speaker cables have spades that work well for the KLH1s. I was thinking of attaching a set of spade connectors to the ABC speaker wires and then using a binder post type "pigtale" and clamping the spades from the ABC and speaker cable together. (not sure if that makes any sense...even to me!!!)

Next, ordering some good metalized polypropylene caps for the crossover. What is crazy is the size of a 100uf cap!!! I actually have a couple of 100uf Erse caps that are nearly 2" in diameter. I'll need to figure a way to secure those onto the crossover board. I am thinking of just putting them on a different board with some leads to the existing crossover, similar to the one inductor that is off the board and screwed to the back of the cabinet.

Finally, I'll be constructing some stands. My niece does sustainable construction and has some great reclaimed wood that I can surely find something cool to use!

 

[Goldjazz]

Sounds like a plan! For the ABC i think it wouod be good if someone with a KLH-1ABC could take of the lid and take some pivs for you to confirm if any of the compinents have changed. I'd be suprised if the boxes were identical and just crossover in speaker changed. Once you get it you can compare to the frequency plots I did with and without abc for the klh1 i had. I will look thru my files i may have taken pics inside my klh1 abc because i recapped it. The little wires for the abc were a pain, i dont follow your plan with the spades but if ut results in correct wiring of abc speakers and amp, sounds like a practical thing to do. I recapped my speakers and noticed a good improvement.

Update: I have an ABC on the way that should be here today. I also found a power supply on amazon that is 12vac @ 1A and 8 W, so that should be plenty. It is a KLH2 ABC but in what I have obsessively researched the past several days, the different bass response between the KLH1, 2, &3 that uses the ABC looks to be due to the crossover. The KLH1 crossover has 2-25uf caps for the woofers. The KLH2 crossover has 2-50uf caps. This is unless I am misunderstanding the crossover circuit.

How are you guys connecting the ABC and the speaker cables to the receiver/amp? My Yamaha CR-600 has spring clip connectors. My current speaker cables have spades that work well for the KLH1s. I was thinking of attaching a set of spade connectors to the ABC speaker wires and then using a binder post type "pigtale" and clamping the spades from the ABC and speaker cable together. (not sure if that makes any sense...even to me!!!)

Next, ordering some good metalized polypropylene caps for the crossover. What is crazy is the size of a 100uf cap!!! I actually have a couple of 100uf Erse caps that are nearly 2" in diameter. I'll need to figure a way to secure those onto the crossover board. I am thinking of just putting them on a different board with some leads to the existing crossover, similar to the one inductor that is off the board and screwed to the back of the cabinet.

Finally, I'll be constructing some stands. My niece does sustainable construction and has some great reclaimed wood that I can surely find something cool to use!

 

[Roger Gorke]

Yes, if you or someone could post pictures inside the KLH1 ABC, that would be great for me to be able to compare with my KLH2 ABC. I have Dayton caps on the way to upgrade the crossover.

Here is my power supply that just arrived.

 

[Goldjazz]

Here is the pic of an original KLH power supply. In the end i sourced this os from a klh2 and used it. Also could only find 2 close up pictures of the klh1 abc. Hopefully somone else can chime in with more

 

[Hobie1dog]

Time to spin the Lp for them

 

[Roger Gorke]

My ABC showed up yesterday. I had some issues with the right channel and realized it was an unrelated (to the ABC) short in the crossover. My new caps should be here in a couple days and the whole crossover will be rebuilt with high quality film caps!

Back to the ABC...OMG!!!! What a tremendous difference. It was like adding a subwoofer. Really strong but not overpowering bass. I can’t wait to get the crossovers rebuilt!!!!

 

[Roger Gorke]

First, I noticed that my speakers do not have the "Acoustically absorbent foam on front baffle reduces high frequency diffraction effects, improves stereo imaging and smoothness of response". http://www.magnat.tv/prospekt/klh.pdf

What is this made of? Is it just acoustic foam or something more "complicated".

I tried cleaning/polishing the old corroded RCA jacks for the input/output. They are pretty, well, old and corroded. The ABC is working well but I am considering installing some new 2x2 RCA jacks, something like this: https://www.mouser.com/ProductDetail/Switchcraft/PJRAS2X2S01X?qs=mcPJWgAPNreoO8Qz1/WyRA==

The issue I am seeing is that the existing RCS jacks are mounted with a rivet at the outer corners vs the new ones are mounted with a screw or rivet at the middle. Maybe I can find some others that mount at the corners.

I was also thinking of installing some more robust speaker cabling for the unit as well...the things I obsess on...

 

[Goldjazz]

I recall the foam being similar in density to eva foam, not sure exactly what it was. Those thin wires from the ABC do look a little cheap, but i don't think it forms any of the signal path. I'm not sure but i assume that the ABC is behaving like a multimeter and is measuring the excursion of the woofers via the back emf that is generated. Its like a closed loop thing where more bass can be got from the woofers than otherwise because we are monitoring them to ensure no damage. I could be wrong about that. So i'd say best leave them be.

First, I noticed that my speakers do not have the "Acoustically absorbent foam on front baffle reduces high frequency diffraction effects, improves stereo imaging and smoothness of response". http://www.magnat.tv/prospekt/klh.pdf

What is this made of? Is it just acoustic foam or something more "complicated".

I tried cleaning/polishing the old corroded RCA jacks for the input/output. They are pretty, well, old and corroded. The ABC is working well but I am considering installing some new 2x2 RCA jacks, something like this: https://www.mouser.com/ProductDetail/Switchcraft/PJRAS2X2S01X?qs=mcPJWgAPNreoO8Qz1/WyRA==

The issue I am seeing is that the existing RCS jacks are mounted with a rivet at the outer corners vs the new ones are mounted with a screw or rivet at the middle. Maybe I can find some others that mount at the corners.

I was also thinking of installing some more robust speaker cabling for the unit as well...the things I obsess on...

 

[Roger Gorke]

Three months later...to the day, I have been really enjoying my KLH 1s! I did notice a bit of distortion in the high end when I turned my Yamaha CR-600 up to about 7. Granted I am usually sitting about 2.5 to 4 on my volume and using the "Loudness" control to lower the overall volume. One other thing I noticed was while listening to the infamous Dave Brubeck Time Out. I thought my left tweeter was distorting at even at low volumes during the opening track Blue Rondo a la Turk. I don't think it is distortion but just how Joe Morello is hitting his ride...maybe using brushes? Maybe someone who has this album can confirm for me?

Also, I am wondering if upgrading the inductor coils in the crossover might be a good upgrade, specifically the 0.4mH and 0.5mH that feed the tweeter and mid speakers. I did notice the originals seemed a bit...smashed for lack of a better term. Even the internal hookup wire seems a bit uninspiring. It seems to be 20 gauge, 18 tops!

I hope everyone in KLH land is doing well!!!

 

[Roger Gorke]

Three months later...to the day, I have been really enjoying my KLH 1s! I did notice a bit of distortion in the high end when I turned my Yamaha CR-600 up to about 7. Granted I am usually sitting about 2.5 to 4 on my volume and using the "Loudness" control to lower the overall volume. One other thing I noticed was while listening to the infamous Dave Brubeck Time Out. I thought my left tweeter was distorting at even at low volumes during the opening track Blue Rondo a la Turk. I don't think it is distortion but just how Joe Morello is hitting his ride...maybe using brushes? Maybe someone who has this album can confirm for me?

Also, I am wondering if upgrading the inductor coils in the crossover might be a good upgrade, specifically the 0.4mH and 0.5mH that feed the tweeter and mid speakers. I did notice the originals seemed a bit...smashed for lack of a better term. Even the internal hookup wire seems a bit uninspiring. It seems to be 20 gauge, 18 tops!

I hope everyone in KLH land is doing well!!!

An update on this issue...it is NOT the speakers...it was an issue with my stylus. It turns out my setup was a bit off. I was using a Shure M91ED with an unknown, presumably aftermarket, stylus. I set the tracking weight as if it were an M91ED with an original N91ED Hi-track stylus at 3/4g- 1.5g. I upped the tracking weight to 2g and the issue went away.

I also just acquired and installed another M91ED with an original Hi-Track Stylus (skinny cantilever) and set it up at 1.2 g. It sounds amazing now. No more high end distortion on the left side!!!

And finally, I did order some new Erse air coil inductors for my KLH 1 Speakers!!!

 

[Roger Gorke]

Continuing the upgrade/restoration of my KLH 1 speakers, I have replaced nearly the entire crossover with higher quality film caps, air core inductor coils (a mix of Dayton and Erse) and new binding posts (I hated those screw things that I could never seem to get really tight). Yesterday I replaced all the internal 20 awg stranded wire with 18 awg solid core. Of course I can't A/B them to hear a before and after difference but of course they sound much better...LOL!

Finally, I think it really does matter what you drive them with. I was using a Yamaha CR-600 that puts out about 35- 40 wpc. Now I am using a CR-800 that puts out 50 wpc and that makes a significant difference!

Maybe next I'll tackle updating the ABC...!

 

[Goldjazz]

Hi Roger, wow you've been busy. Nice work. Glad that you a hearing an improvement. Yeah will be interesting to see if recapping the ABC makes a further improvement. Sounds like you are pulling together a very nice system.

 

[Roger Gorke]

Hi Roger, wow you've been busy. Nice work. Glad that you a hearing an improvement. Yeah will be interesting to see if recapping the ABC makes a further improvement. Sounds like you are pulling together a very nice system.

Yeah, thanks! I am constantly futzing with stuff, probably to a fault.

Might you have an overall picture of the board inside your ABC? I saw your list of the 10 electrolytics. Mine (for a KLH2) only has four (4), like the pictures in post #116 of this thread. The pictures you posted have an electrolytic right by one of the 22uf caps vs a couple of what appear to be tantalums. I'd like to recap mine but also maybe modify it to be more like an ABC for a KLH1.

Thanks