Kenwood L-01A Recap

Tinco

New Member
Hi guys,

I received a Kenwood L-01A and intend to replace the electrolyte caps. I have done a recap before, so I got the basics down.

I'm putting the cap list together now, and am wondering what I should order. For the Marantz I did I replaced everything with Panasonic FM's, because they were cheap yet highly regarded.

This amp is of a much higher grade, and thus deserving of more expensive caps. The true Marantz fans apparently replace everything with Elna Silmic II's to achieve the "Marantz sound".

First question:
Does Kenwood have a specific sound that goes with a particular kind of cap? I would like to keep it as close to its original sound as possible.

Second question:
There's two big capacitor boxes in the amp that say 63v 18000uF on them. Should I open them up and replace them as well, or would they withstand the test of time better than regular electro caps because they're sealed?

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Any feedback is much appreciated!

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I did some research, if I do have to replace the big power supply caps there's basically two options.

Option 1: Panasonic THA series at 8 euro per piece

Option 2: At 4 times the price, and more than 10% more capacitance the Mundorf MLytic AG, for a little more I could also do two 10000uF MLytics, which would bring it closer to 10% over spec.

If I would like to keep the restoration under 250 euro, going for the Mundorfs would blow a pretty big hole in that budget. Would that be worth it, or should I look first what's left of the budget after the audio path?
 
Hi Tinco,

It's rather a monologue here it seems :).

Well, the Dutch then need to support the Dutch I guess :bigok:

To my more than humble opinion it would be worthwhile to replace the power supply caps and to my even more humble opinion I think the Panasonics will do fine.

I still need to do a "stereo"-rebuild of two similar amps, one with Panasonic caps and one with Mundorf caps to find out for myself if I'll be able to hear the difference, but I'll probably will not have the time to do it in the near future (the caps I already have though).

I do wonder what's inside the boxes and how the caps are mounted at the board. Before you consider ordering replacements I think you'd better check out size and way of mounting (screw, snap in?).

The Mundorfs - if you want to try them out - are also sold by a Dutch company, PM me for details.
 
Hi guys,

First question:
Does Kenwood have a specific sound that goes with a particular kind of cap? I would like to keep it as close to its original sound as possible.

In my opinion a cap doesn't have a sound, only the total circuit has a sound. The Kenwood's sound is "fast" and "controlled" Very wide frequency range (0-500KHz!) low noise, but sometimes a bit thin. Combine it with a "warm" speaker (Kef Reference Model One, B&W series 80 etc.) It doesn't like to drive electrostatic speakers.

Just use good quality normal caps, quality industrial caps are much better than "audio grade" stuff.

The protection circuit uses "Low leakage caps" I would replace them with such caps. (I used Nichon KL)

Second question:
There's two big capacitor boxes in the amp that say 63v 18000uF on them. Should I open them up and replace them as well, or would they withstand the test of time better than regular electro caps because they're sealed?

I left them alone, capacity and ESR measured good, and you'll never find anything similar. I once read about a Japanese guy that drilled-out the caps from the block, to reuse the block with new caps.



Hi Tinco,

I did a refurbish of this amp a few years back.

When I got it all stuff was original, normal grade Elna. I had problems with connection, only AUX input worked etc. I replaced all caps (expect for the large blocks) with Panasonic FM or Nichon MUSE. The sound quality and signature remained largely the same (which is very good!!!). I also replaced all the relays (with Axicom D2n) wich helped, but not for all problems. It turned out the vias on the preamp board were not well. I resoldered all vias and all connection problems were gone. I also replaced the input RCA sockets with nice gold ones (looks much better), and replaced the speaker outputs with 4mm sockets. Last, I replaced the bias and offset controllers with Burns multiturn, and cleaned the connections between the pre and main amp. That helped to make the idle current more stable. But still the idle current is not that stable, I need to realign the Bias each 3-5 months.

Sound quality is fantastic, and it has no problem driving my B&W 802s80 speakers, which are not easy to drive! But reliability remains a serious problem, especially the coupling between the idle current and temperature.

Also keep in mind that the power transistors are very hard to find, and expensive. (I had to replace one channel, for 15 euro's per transistor :( )

I'm considering an upgrade to something like an Accuphase E405, to keep the perfect sound quality, and get a more reliable amp. But those are ca 1500 euros, whereas my L01a was 300.....
 
Thanks for the replies you guys, seems like there's something Dutch about this amp ;)

If what Hobbit13 says is true and I'd need to drill out the power caps to replace them, that seems like it would be a rather destructive action. I'll try and measure them, I don't have any equipment for measuring large capacitances accurately, so I think I have to use a stopwatch, I'll find out how to measure ESR.

So my next step is going to be to build the cap list, I'll just go with Panasonic FM's for everything as they seem to be the easiest to acquire. After I've recapped it and turned it on I'll try and find out why one of its channels it's broken.

Hobbit13, about the idle current what do you mean by that, is that the DC voltage over the speaker outputs when it's idle? I plan on giving it back to my dad when I'm done, but he wouldn't like to break out a multimeter and readjust some internal pot every 3-5 months, is there something I could do to solve that problem or is it very inherent to the design? Was it something they did even fresh from the factory?

It would probably be driving the "De Vos" loudspeakers my dad has (http://www.devosloudspeakers.com/)
 
Hey Hobbit13, I think you've not been working on original hardware, either that or mine is not original, because there were only 3 Elna caps in this thing. Every other cap is branded TRIO.

For future reference, here is the cap list:

Code:
Power amp:

47uF 10V, c11
10uF 16V, c12
330uF 16V, c13
4.7uF 35V, c14
10uF 25V, c15
220uF 10V, c16,c29,c30

Back of power amp (super sneaky bodge caps):
10uF 25V
2.2uF 50V

Preamp:

100uF 6.3V, c1-c4
2.2uF 50V, c7-c10
220uF 10V, c15-c18
2.2uF 35V, c19,c20
220uF 16V, C21,c22
330uF 16V, C23,C24
100uF 25V, C25-C28
100uF 16V, C29,C30

220uF 6.3V, C47, C48
4.7uF 35V, C49,C50
47uF 10V, C51, C52
100uF 35V, C55, C56
47uF 35V, C57, C58
100uF 10V, C59-C62
47uF 35V, C63-C66
1700uF 42V, C67, C68
2200uF 25V, C71,C72

Audio:
100uF 25V, C15,C16
33uF 25V, C17,C18
33uF 10V, C19,C20
100uF 35V, C25,C26
100uF 63V, C45-C48

LL 33uF 16V, c51-c54
LL 10uF 16V, C52
LL 22uF 16V, C55

Switch:
470uF 16V, C3-C6
47uF 16V, C7
220uF 10V, C8

Power supply:
470uF 16V,  C2

No idea why there were 2 extra caps on the back of the power amp, you had those too hobbit13?

So I found Panasonic FM or FC replacements for everything. I did some research on the low leakage caps, and it seems the internet thinks a modern Panasonic FC is at least as good as the old low leakage Elna's. So I think I'm good there as well. (Getting the Nichicons is rather expensive here, unless you have a good address for me Hobbit13?)

The order went out, this is my shopping list:

Code:
1848391	4	 CAP, ALU ELEC, 33UF, 35V, RAD; Product R	EEUFM1V330
1848386	4	 CAP, ALU ELEC, 47UF, 25V, RAD; Product R	EEUFM1E470
1219453	8	 CAP, ALU ELEC, 100UF, 10V, RAD; Product	EEUFM1A101
1219468	8	 CAP, ALU ELEC, 220UF, 25V, RAD; Product	EEUFM1E221
1219478	8	 CAP, ALU ELEC, 100UF, 50V, RAD; Product	EEUFM1H101
1219466	8	 CAP, ALU ELEC, 100UF, 25V, RAD; Product	EEUFM1E101
1219454	10	 CAP, ALU ELEC, 220UF, 10V, RAD; Product	EEUFM1A221
1219461	3	 CAP, ALU ELEC, 330UF, 16V, RAD; Product	EEUFM1C331
1219462	5	 CAP, ALU ELEC, 470UF, 16V, RAD; Product	EEUFM1C471L
1219472	2	 CAP, ALU ELEC, 2200UF, 25V, RAD; Product	EEUFM1E222L
9692517	5	 CAP, ALU ELEC, 100UF, 63V, RAD; Product	EEUFC1J101
1848456	7	 CAP, ALU ELEC, 2.2UF, 50V, RAD; Product	EEUFC1H2R2
1848459	3	 CAP, ALU ELEC, 4.7UF, 50V, RAD; Product	EEUFC1H4R7
1848447	6	 CAP, ALU ELEC, 47UF, 35V, RAD; Product R	EEUFC1V470
2326254	2	 CAP, ALU ELEC, 1800UF, 50V, RAD; Product	EEUFC1H182
9692363	5	 CAP, ALU ELEC, 10UF, 50V, RAD; Product R	EEUFC1H100
2326314	1	 CAP, ALU ELEC, 22UF, 35V, RAD; Product R	EEUFC1V220
1848445	1	 CAP, ALU ELEC, 33UF, 35V, RAD; Product R	EEUFC1V330
 
Hey Hobbit13, I think you've not been working on original hardware, either that or mine is not original, because there were only 3 Elna caps in this thing. Every other cap is branded TRIO.

Doesn't mean much, TRIO did not make there own caps, and the prints were made by Elna. My L01a is an early one, with a modification around the DC switch applied afterwards, which is already present in the service manual.
If yours has TRIO caps, there is definitely a large change yours is original.


No idea why there were 2 extra caps on the back of the power amp, you had those too hobbit13?

So I found Panasonic FM or FC replacements for everything. I did some research on the low leakage caps, and it seems the internet thinks a modern Panasonic FC is at least as good as the old low leakage Elna's. So I think I'm good there as well. (Getting the Nichicons is rather expensive here, unless you have a good address for me Hobbit13?)

The 2.2uF (bipolar!?) was not in the service manual, but present in my amp. The 10uFs are listed in the service manual.

I got the low leakage via Mouser, they were not expensive.


As for your previous post on the idle current (also called bias current), it is explained in the service manual, and a very important step after replacing components. Otherwise the amp will run way too hot, or too cold. (and in this particular amp it's hard to get it right).

Please remember that this amp is loaded with unobtainable high-end fets and transistors. So if you make a mistake, repair will be very hard / expensive!!!
 
Hello!
very nice amp you got there! For this amp I would probably not touch the big electrolitics unless they are not in the specs in terms of cappacity and ESR.
Moreover, I think that this will deserve better grade capacitors than Panasonic FM/FC (which are good caps).
I would buy Elna Silmic II (if you can find originals, be aware of fake ones!) although they are much more expensive or Nichicon Muze KZ/FG series. I used in the past Nichicon Muze KZ or FG in reccaping a Luxman L-5 and I was/am very satisfied with this choice.
By the way, I own the more newer (if I can call it like this, the years gap between them being a year or two) edition of this amplifier, KA-1000 with Sigma Drive technology. Superb sound from stock components... Yours is probably made better than KA-1000 which has a lot of plastic in the structure.
Keep us posted with the transformation of this superb amplifier!:thmbsp:
 
I could get Elna Silmic II's or Muze KZ's from mouser, but I've already received the Panasonics. I've read a lot about all these caps, and there's lots of disagreement about whether there's any audible difference between them, some even argue even the cheapest good brand (Panasonic) caps are good enough for any audio grade circuit, and much better than any cap was 30 years ago. I don't know what to believe :)

So I received the caps, and the IPA. I noticed I'll have to take everything out of the case to be able to test and adjust it, so I'll do that, take some before pictures, and then clean and recap and take some more pictures :) Hopefully I'll have time to this somewhere this weekend.

I'll definitely read through the service manual carefully Hobbit13, you are right I wouldn't want to risk damaging anything. BTW, you live(d ?) very near to me, I think I might even have met you or at least know your face since we went to the same uni in the same period. If you'd like to meet up with me some time please let me know :D
 
I'll definitely read through the service manual carefully Hobbit13, you are right I wouldn't want to risk damaging anything. BTW, you live(d ?) very near to me, I think I might even have met you or at least know your face since we went to the same uni in the same period. If you'd like to meet up with me some time please let me know :D


Panasonic FC is better spec-wise than all those "audiograde" caps. But those caps still can have nice "character". Especially when they are placed in the signal line (as DC blocker), the "character" is very important. But in the L01a all caps in the signal line are metal film.

I still live near the university, you are welcome to listen to my L01a and compare it to yours.
 
Cool, I might take you up on that offer :)

I have two more small question about the process. I just finished cleaning the preamp board (thick layer of tar on there, took a whole lot of IPA to get it decently clean) and I want to start replacing the caps.

On my Marantz testing was easy, I didn't have to disconnect any board to do the soldering, so I could just replace a few caps, test it, and move on. In this one, I had to desolder a bunch of wires, and completely remove the board on chassis to even get a look at its top side. Did you rebuild the amp outside of its case to test it? Or did you lengthen some wires, or some other technique?

Second, I could not get the big 1700uF caps on the preamp board and got 1800uF instead. I figured since there's 20% deviation on these things anyway the precise value wasn't very important. Is that correct?
 
By the way, I own the more newer (if I can call it like this, the years gap between them being a year or two) edition of this amplifier, KA-1000 with Sigma Drive technology. Superb sound from stock components... Yours is probably made better than KA-1000 which has a lot of plastic in the structure.

I looked a bit into the KA1000, and I think that it is hardly related. It also has an external PSU, but the whole electrical concept, component choice and build quality is totally different. I like the outer appearance of the KA1000 better: it has real glass and it is not as bulky. The KA1000 is much more modern, with the Sigma Drive, Fade circuit etc. The LA01a doesn't have anything "new" (besides the nonmagnetic enclosure) but the component choice is fantastic (peculiar similar to Accuphase of the same period).

For example, the phone stage of the KA1000 is a simple opamp with RIAA filter, whereas the L01a has a dedicated 40x20cm circuit board full of low-noise FETs and massive copper ground bars.

The newer generation L-series do have a Sigma driver amplifier, and as such are closer related to the KA1000, but those are very rare. The L06m is somewhat affordable, but the L08m monoblocks and the L02a integrated are unobtainable.

Cool, I might take you up on that offer :)

I have two more small question about the process. I just finished cleaning the preamp board (thick layer of tar on there, took a whole lot of IPA to get it decently clean) and I want to start replacing the caps.

On my Marantz testing was easy, I didn't have to disconnect any board to do the soldering, so I could just replace a few caps, test it, and move on. In this one, I had to desolder a bunch of wires, and completely remove the board on chassis to even get a look at its top side. Did you rebuild the amp outside of its case to test it? Or did you lengthen some wires, or some other technique?

Second, I could not get the big 1700uF caps on the preamp board and got 1800uF instead. I figured since there's 20% deviation on these things anyway the precise value wasn't very important. Is that correct?

I made a connector for the wirewraps at the front right, those pins are 5.08mm appart, thus normal 2.54mm pitch connectors can be used. I kept the ground wires in place, the rest is already made with connectors.

The capacitor value doesn't matter anything. The transformers can easily provide enough power.
 
I looked a bit into the KA1000, and I think that it is hardly related. It also has an external PSU, but the whole electrical concept, component choice and build quality is totally different. I like the outer appearance of the KA1000 better: it has real glass and it is not as bulky. The KA1000 is much more modern, with the Sigma Drive, Fade circuit etc. The LA01a doesn't have anything "new" (besides the nonmagnetic enclosure) but the component choice is fantastic (peculiar similar to Accuphase of the same period).

For example, the phone stage of the KA1000 is a simple opamp with RIAA filter, whereas the L01a has a dedicated 40x20cm circuit board full of low-noise FETs and massive copper ground bars.

The newer generation L-series do have a Sigma driver amplifier, and as such are closer related to the KA1000, but those are very rare. The L06m is somewhat affordable, but the L08m monoblocks and the L02a integrated are unobtainable.
I agree with you. KA-1000 is a little bit different from L-01A. I would prefer the latter if you ask me, it is much better made. Although, I would be very curious about a sound comparison. What a treat would be that?!:tresbon:
 
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