Kondo KSL-M77 phono and preamp clone project
Hey guys. It's been a while.
I got burnt out from audio and sort of took a break. Multiple reasons, and too many other things going on.
I recently put up some speakers for sale, and managed to find a deal with someone who wanted to make a trade. So for a pair of Aucharm full range 12" speakers I wasn't going to use, I got a B&K AVR 202 with hum problems, a vintage Trygon T50-2 power supply, and this KSL-M77 project. I'm happy with the trade, and it gives me some stuff to play with as I find the time. I should have a power transformer that would be suitable for this kit. Just in the value of the caps and enclosure alone I think this was a decent trade, even if I gut it and build something else without boutique parts or circuitry.
Does anybody happen to have details on these? All I really find is PCB photos but no real detailed specs on them. I'll post what I could find.
Looks like this is very close to my kit-
Audio KONDO AUDIONOTE M77 Line and Phono AMP HiFi Tube Preamplifier Board - Free Shipping - ThanksBuyer
Anybody recognize those pots used here? Looks like one volume, one balance, and a source selector.
I think this is the correct schematic. From what I can tell this sucker takes eight (8)! 12AY7 tubes!!??! I may see if I can modify it to take something like 6N1P or 6CG7 since I can mix and match those with some parts value changes.
Hey guys. It's been a while.
I got burnt out from audio and sort of took a break. Multiple reasons, and too many other things going on.
I recently put up some speakers for sale, and managed to find a deal with someone who wanted to make a trade. So for a pair of Aucharm full range 12" speakers I wasn't going to use, I got a B&K AVR 202 with hum problems, a vintage Trygon T50-2 power supply, and this KSL-M77 project. I'm happy with the trade, and it gives me some stuff to play with as I find the time. I should have a power transformer that would be suitable for this kit. Just in the value of the caps and enclosure alone I think this was a decent trade, even if I gut it and build something else without boutique parts or circuitry.
Does anybody happen to have details on these? All I really find is PCB photos but no real detailed specs on them. I'll post what I could find.
Looks like this is very close to my kit-
Audio KONDO AUDIONOTE M77 Line and Phono AMP HiFi Tube Preamplifier Board - Free Shipping - ThanksBuyer
Anybody recognize those pots used here? Looks like one volume, one balance, and a source selector.
I think this is the correct schematic. From what I can tell this sucker takes eight (8)! 12AY7 tubes!!??! I may see if I can modify it to take something like 6N1P or 6CG7 since I can mix and match those with some parts value changes.
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The volume pot looks like an Audio Note. Balance looks like a Noble
And yet they are all fake, even the generic switch
Sorry, assumed those came with the kit in the link. If they were added by a previous owner, they are quite likely real.
Yeah, I figure the line section would do well reconfigured for 6N1P or 6CG7, not sure about my plan for the phono section yet. I haven't done a cascode for a while, but something I would like to do is use a better PSU filter with it.
I don't need excessive gain, so I'm thinking that 6N1P would be a good choice for use with an external Mosfet follower type of amplifier, there the gain would be useful.
Maybe run 12AT7 in the phono section? I have two of those. Need to recalculate the RIAA components though.
I don't need excessive gain, so I'm thinking that 6N1P would be a good choice for use with an external Mosfet follower type of amplifier, there the gain would be useful.
Maybe run 12AT7 in the phono section? I have two of those. Need to recalculate the RIAA components though.
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KSL-M77 Build
Except for a few of the finer points, I got my KSL-M77 going today! I need to straighten up the wiring, connecting the inputs and finish testing and then put the top on the cabinet.
I went with two Hammond Transformers from AES. The reason for 2 is that I could not find a single transformer that would do 250-0-250 , 6.3V and 4 amps of 12.6V. There was no room inside the enclosure si I mounted them on the outside.
I went with the no tube, cap or cabinet model from Douk. I got a mixture of tubes running in it and for a basic collection of 12AU7 and 12AX7 oulls, it sounds great!
I am looking at getting an octet of Electro-Harmonix 12AY7s from eBay for $120. Does anyone have any experience with them?
I am impressed by the quality of parts they DID send. Most impressed by the 3mm PCB thickness and heavy gold plated runs
Except for a few of the finer points, I got my KSL-M77 going today! I need to straighten up the wiring, connecting the inputs and finish testing and then put the top on the cabinet.
I went with two Hammond Transformers from AES. The reason for 2 is that I could not find a single transformer that would do 250-0-250 , 6.3V and 4 amps of 12.6V. There was no room inside the enclosure si I mounted them on the outside.
I went with the no tube, cap or cabinet model from Douk. I got a mixture of tubes running in it and for a basic collection of 12AU7 and 12AX7 oulls, it sounds great!
I am looking at getting an octet of Electro-Harmonix 12AY7s from eBay for $120. Does anyone have any experience with them?
I am impressed by the quality of parts they DID send. Most impressed by the 3mm PCB thickness and heavy gold plated runs
I have a matched EH 12AY7 octet from eBay. Well...they work OK
I had another problem with this kit. The 1nF capacitor in the phono stage seems not to be a proper value. In my case, there is about +1.5-2dB deviation at 20kHz, rising through the spectrum. 1.3nF (1.5 nF + 10nF in series) gives a good RIAA frequency response.
I had another problem with this kit. The 1nF capacitor in the phono stage seems not to be a proper value. In my case, there is about +1.5-2dB deviation at 20kHz, rising through the spectrum. 1.3nF (1.5 nF + 10nF in series) gives a good RIAA frequency response.
I have no experience with the Electro Harmonix version of the 12AY7.
But I use JJ 12AY7 that I purchase from Eurotubes.com. They work great.
They re-test the tube parameters including noise, after they get them from the JJ factory in Slovakia.
Eurotubes are in Milwaukie, OR. I drive right over and get my tubes there.
They ship to the US and some overseas countries.
Those JJ 12AY7 tubes use spiral filaments, for less noise.
But I use JJ 12AY7 that I purchase from Eurotubes.com. They work great.
They re-test the tube parameters including noise, after they get them from the JJ factory in Slovakia.
Eurotubes are in Milwaukie, OR. I drive right over and get my tubes there.
They ship to the US and some overseas countries.
Those JJ 12AY7 tubes use spiral filaments, for less noise.
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Congrats!
I’m a bit late to this thread but was reading about your project today.
Now that you’ve been running it for a few weeks, how do you like it?
anybody know the reason for this 10Meg resistor?
Hi, also in the process of building this clone, and I came across this 10M resistor for the upper triode in the input stage. Simulation shows strong increase in the higher frequencies, that disappears when the resistor is reduced to ~200k.
Scratched my head but couldnt come up with an explanation..... Is this on purpose? Kondo magic?
Hi, also in the process of building this clone, and I came across this 10M resistor for the upper triode in the input stage. Simulation shows strong increase in the higher frequencies, that disappears when the resistor is reduced to ~200k.
Scratched my head but couldnt come up with an explanation..... Is this on purpose? Kondo magic?
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I have a matched EH 12AY7 octet from eBay. Well...they work OK
I had another problem with this kit. The 1nF capacitor in the phono stage seems not to be a proper value. In my case, there is about +1.5-2dB deviation at 20kHz, rising through the spectrum. 1.3nF (1.5 nF + 10nF in series) gives a good RIAA frequency response.
Saw the same in simulation, you could increase the 33k resistor to 50k, that should help as well.
My build unfortunately isnt ready yet, but will certainly take some measurements when done...
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I wouldn't bet on the simulation in this case .That 10 meg bias is using a tube behavior that's not preesent in any tube model.Hi, also in the process of building this clone, and I came across this 10M resistor for the upper triode in the input stage. Simulation shows strong increase in the higher frequencies, that disappears when the resistor is reduced to ~200k.
Scratched my head but couldnt come up with an explanation..... Is this on purpose? Kondo magic?
Grid leak bias, how does it work?
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in the link you shared, somebody had built himself a 250MOhm probe, considering to do the same.... in any case, this will be tricky as this is the "upper" triode, and it will see the grid voltage relative to its cathode.
in any case, that should put this triode in relatively low current (or high impedance), still the DC voltages in that circuit appear to be fine, so the operating conditions seem to be chosen correctly.
In SRPP, I would expect a much lower grid resistor and some interaction between the two triodes as a result, well-known I guess. But not in this case, I am still wondering what the purpose is....
in any case, that should put this triode in relatively low current (or high impedance), still the DC voltages in that circuit appear to be fine, so the operating conditions seem to be chosen correctly.
In SRPP, I would expect a much lower grid resistor and some interaction between the two triodes as a result, well-known I guess. But not in this case, I am still wondering what the purpose is....