No harshness at all with "my" Tocos, and very faithfull treble compared to a refence set up (directly soldered resistors). In case you lok for the "truth", it is neither complicated nor expensive to take a few quality resistors directly soldered and use them as absolute reference - just chose them so you get the attenuation you need as not variable, and match your pot position accordingly.
But then these findings are just me with my Tocos (perhaps I got lucky) and my loudspeakers are very revealing while not needing things to be smoothed out, so who knows...
Important is people are happy with "their" results, as in my case re treble and human voices LS make by far the most, much more than the Tocos & Co... magnetostats and some electrostats are my friends... or some direct voice from my family members who are gifted opera singers
At the end a system is just that, and getting the right tuning is far more complicated from swapping / upgrading LS than tuning other components.
Having said that, I would love to toy with a Muses volume arrangement, just for the sake of it as Papa is using it... but so far no simple inexpensive kit around sadly.
Claude
Volume Controls | academyaudio
Inexpensive muse volume control. Requires bipolar supply though.
I bought Tocos 50k (because of ClaudeG 
) on eBay, it just arrived today. First thing I noticed is that it is very light weight, maybe half the weight of my Blue Alps. I didn't think it was going to work, but nevertheless replaced the Blue Alps in my B1Korg. Luckily it played music
I find it much more transparent and revealing than Alps. And a little bit thinner in bass department.
I read somewhere on this forum that fake Tocos are detected by their 'miniscule' weight and I wonder if I got the fake one. And how good the real thing would have sounded
) on eBay, it just arrived today. First thing I noticed is that it is very light weight, maybe half the weight of my Blue Alps. I didn't think it was going to work, but nevertheless replaced the Blue Alps in my B1Korg. Luckily it played music I find it much more transparent and revealing than Alps. And a little bit thinner in bass department.
I read somewhere on this forum that fake Tocos are detected by their 'miniscule' weight and I wonder if I got the fake one. And how good the real thing would have sounded
I have spent some time playing with coupling caps on my Korg B1.
started with 6.8uf Wima mylar caps bypassed with a .1uF polypropylene cap. Sound is good. A little nervous in the high frequencies, but very airy and open.
I added 100UF silmics to the mylar caps...so effectively 100UF silica/6.8uf mylar bypass/.1 Poly bypass. I let them burn in for a couple days.
Sound is not as different as anticipated. Transient speed is lower but sound is a bit fuller. Treble is tamed a bit, at the expense of soundstage size and precision. But overall the sound is less nervous and more liquid and weighty. But not a huge change.
I will try only Polypropylene caps next.
My experience with the Korg is that it is somewhat bright and possesses a supernatural soundstage until volumes get high or the music gets complex. It is definitely my favorite preamp for simpler music or hearing ambience in a recording. It's almost as if some reverb or delay has been added to the signal chain for those of you with guitar or recording experience. Makes my solid state preamp sound dry with no bloom. But it gets compressed and hard at high volumes or with complex music. But coming from the solid state preamp relm...it's been a revelation.
Since I like it, I am trying to minimize the shortcomings...I have some PEC pots coming to replace the Tocos Cosmos which are great but a little shrill. Maybe not a good match for this circuit in my opinion. I will try polypropylene caps. Perhaps a different set of interconnects is in order.
My dream preamp would be the soundstage of the Korg with the dynamics and composure of a good solid state preamp. Does this exist?
started with 6.8uf Wima mylar caps bypassed with a .1uF polypropylene cap. Sound is good. A little nervous in the high frequencies, but very airy and open.
I added 100UF silmics to the mylar caps...so effectively 100UF silica/6.8uf mylar bypass/.1 Poly bypass. I let them burn in for a couple days.
Sound is not as different as anticipated. Transient speed is lower but sound is a bit fuller. Treble is tamed a bit, at the expense of soundstage size and precision. But overall the sound is less nervous and more liquid and weighty. But not a huge change.
I will try only Polypropylene caps next.
My experience with the Korg is that it is somewhat bright and possesses a supernatural soundstage until volumes get high or the music gets complex. It is definitely my favorite preamp for simpler music or hearing ambience in a recording. It's almost as if some reverb or delay has been added to the signal chain for those of you with guitar or recording experience. Makes my solid state preamp sound dry with no bloom. But it gets compressed and hard at high volumes or with complex music. But coming from the solid state preamp relm...it's been a revelation.
Since I like it, I am trying to minimize the shortcomings...I have some PEC pots coming to replace the Tocos Cosmos which are great but a little shrill. Maybe not a good match for this circuit in my opinion. I will try polypropylene caps. Perhaps a different set of interconnects is in order.
My dream preamp would be the soundstage of the Korg with the dynamics and composure of a good solid state preamp. Does this exist?
With B1K, I found that the pot value was a more important variable than the make and model of pot. I tried several different makes of 50K vs several different 20K and found I much prefer a 20K over a 50K pot with this preamp. 20K took out any residual shrillness. This may be due to the loading on my source and the resultant differences in noise and transient response and how those are amplified by the Korg. But I found 20K works for me.
That's good. Since the PEC pots on order are 25K.
I did try the Tocos Cosmos (50K) with a 10K log fake resistor. Not a lot of tonal difference.
Hi Hikari1,
"My experience with the Korg is that it is somewhat bright and possesses a supernatural soundstage until volumes get high or the music gets complex. "
I would say bright only depending on the caps, as many in the signal path, but otherwise the basic set up is quite the opposite IMHO, eg a pre that is rather "smoothly open"... sound and colour or just me?
Re Korg losing composture at higher levels, I am with you and prefered a set up with half the recommended H2 but then it all depends on you entire system and the sum you have and also listening levels and gains in the entire system. Not easy that one...
Re Korg losing composure on complex music, I would say the quite the opposite in fact. That is of course as long as the complex passages aren't louder / have more energy than the simple ones. But if you are fine on simple passages and the message gets complex AND with more energy then you might move into "a not as good bracket". But at the end it is in my case not the complexity but rather the loudness/ total energy level which is the key factor. And that leads us to the above paragraph...
That's one of the reasons, on complex operas, why I decided to reduce the H2 level from the initialy suggested value (which was just that, a suggested one to play with as Papa outlined it, and he really encouraged us to play with it!), to half of it in real listening conditions. And I might tweak that again, who knows, depending on power amps harmonics, overall gain structure etc.
All I want to say is please play with the voltage value and the H2 level as that makes quite a difference, for sure as much as caps and pots... it is so easy to do but we don't read so much about that tuning, whereas Papa gave us a fab tool that can be really and easily tuned from 9V to 15V with many variations on the theme...
Have you tried reducing your H2 level a tad, to see if your dindings are still the same?
All IMHO, sharing my findings and limited understanding of that voltage tuning which I found really THE main factor of that pre
Claude
"My experience with the Korg is that it is somewhat bright and possesses a supernatural soundstage until volumes get high or the music gets complex. "
I would say bright only depending on the caps, as many in the signal path, but otherwise the basic set up is quite the opposite IMHO, eg a pre that is rather "smoothly open"... sound and colour or just me?
Re Korg losing composture at higher levels, I am with you and prefered a set up with half the recommended H2 but then it all depends on you entire system and the sum you have and also listening levels and gains in the entire system. Not easy that one...
Re Korg losing composure on complex music, I would say the quite the opposite in fact. That is of course as long as the complex passages aren't louder / have more energy than the simple ones. But if you are fine on simple passages and the message gets complex AND with more energy then you might move into "a not as good bracket". But at the end it is in my case not the complexity but rather the loudness/ total energy level which is the key factor. And that leads us to the above paragraph...
That's one of the reasons, on complex operas, why I decided to reduce the H2 level from the initialy suggested value (which was just that, a suggested one to play with as Papa outlined it, and he really encouraged us to play with it!), to half of it in real listening conditions. And I might tweak that again, who knows, depending on power amps harmonics, overall gain structure etc.
All I want to say is please play with the voltage value and the H2 level as that makes quite a difference, for sure as much as caps and pots... it is so easy to do but we don't read so much about that tuning, whereas Papa gave us a fab tool that can be really and easily tuned from 9V to 15V with many variations on the theme...
Have you tried reducing your H2 level a tad, to see if your dindings are still the same?
All IMHO, sharing my findings and limited understanding of that voltage tuning which I found really THE main factor of that pre
Claude
I have played with H2 form 9V to 11V. Extensively.
I prefer it lower (9.25ish) which lets the Korg B1 do what it does well. I agree it's better at high volumes/complex stuff with less H2 but it kind of loses it's charm I think.
At higher voltages (less H2)it has a sound more similar to my SS preamps (Salas DCG3, Juma Current Mirror, Pass B1 rev2) and it loses some of that supernatural soundstage that makes it special.
This, of course, may be power amp and speaker dependent. Power amp is an F5 turbo, speakers are KEF R700 3 ways (89 db). "Loud" for me is about 90db at the listening chair.
I prefer it lower (9.25ish) which lets the Korg B1 do what it does well. I agree it's better at high volumes/complex stuff with less H2 but it kind of loses it's charm I think.
At higher voltages (less H2)it has a sound more similar to my SS preamps (Salas DCG3, Juma Current Mirror, Pass B1 rev2) and it loses some of that supernatural soundstage that makes it special.
This, of course, may be power amp and speaker dependent. Power amp is an F5 turbo, speakers are KEF R700 3 ways (89 db). "Loud" for me is about 90db at the listening chair.
Taste and colours... Thanks for sharing all this, interesting.
I found my optimum was less H2, retaining that excellent soudstage and addicting charm while not overblowing it, also having that superb drive without losing accuracy on complex stuff.
Very different approaches I guess: indeed I didn't want my Korg B1 to differ from my (passive) pre: I wanted initialy to see if it stood a chance against it (and didn't think so, considered it more as an intriguing toy). And it bettered it, well done Papa! But admittely I went for a compromise which, well noted IMHO and to my ears, retained most of its beautifull particularities (what a beautifull sound...) while not losing an inch on more objective criteria (that are indeed usualy more traditional SS or passive territory).
Loud (very in fact, I can rather do with 85 to 87 average if longer listening session and not just that Queen hit in loop for 20', LOL ) is also for me 90dB average at listening position - produced by a pair of 87dB/W/m Infinity Renaissance 90.
At the end I am still amazed at how many followers get tricked and facinated by what I suspected initialy to be only a tiny and intriguing sound box... and now I am part of the first row saying this pre is a giant killer and at the end of the day probably just what I really wanted to listen to since ages without knowing it, eventhough the engineer in me realizes I got tricked and it still lasts so might be long term, LOL!
Thanks again Papa and enjoy your B1 Korg very much Hikari1, whatever yoru flavour
Claude
I found my optimum was less H2, retaining that excellent soudstage and addicting charm while not overblowing it, also having that superb drive without losing accuracy on complex stuff.
Very different approaches I guess: indeed I didn't want my Korg B1 to differ from my (passive) pre: I wanted initialy to see if it stood a chance against it (and didn't think so, considered it more as an intriguing toy). And it bettered it, well done Papa! But admittely I went for a compromise which, well noted IMHO and to my ears, retained most of its beautifull particularities (what a beautifull sound...) while not losing an inch on more objective criteria (that are indeed usualy more traditional SS or passive territory).
Loud (very in fact, I can rather do with 85 to 87 average if longer listening session and not just that Queen hit in loop for 20', LOL ) is also for me 90dB average at listening position - produced by a pair of 87dB/W/m Infinity Renaissance 90.
At the end I am still amazed at how many followers get tricked and facinated by what I suspected initialy to be only a tiny and intriguing sound box... and now I am part of the first row saying this pre is a giant killer and at the end of the day probably just what I really wanted to listen to since ages without knowing it, eventhough the engineer in me realizes I got tricked and it still lasts so might be long term, LOL!
Thanks again Papa and enjoy your B1 Korg very much Hikari1, whatever yoru flavour
Claude
Yes, it's nice to have many different preamps...each have their own flavor.
For 80% of the stuff I listen too (mostly classic rock and indie rock) the Korg is the best.
For the other 20% one of the SS preamps seem to work better, while sounding somewhat dry compared to the Korg.
But I am more than 100% satisfied with the Korg B1. It does what it does very well. No component is perfect.
For 80% of the stuff I listen too (mostly classic rock and indie rock) the Korg is the best.
For the other 20% one of the SS preamps seem to work better, while sounding somewhat dry compared to the Korg.
But I am more than 100% satisfied with the Korg B1. It does what it does very well. No component is perfect.
Just received a 50k Tocos Cosmos volume pot from the eBay seller ClaudeG referenced. I am also going to switch to Polypropylene film caps for the inputs. For the output caps, I might bypass the stock 10uF Nichicon FW with a pair of 0.01uF Polypropylene film caps or dig through my stash for a pair of NOS 4.7uF Black Gate N non-polar electrolytic caps. Using the diyAudio store 1U chassis, so there isn’t much room to fit bulky 3.3uF film caps in the output.
I wonder if ClaudeG’s combination of film caps and the Tocos Cosmos volume pot is providing the improved bass weight and detail.
For now, the stock Completion Kit components and chassis are great. The only thing I would change with the chassis is to go with top and bottom chassis cover plates without the ventilation slots. I think I have a sensitive microphonic Korg NuTube, and mounting the PCB on the vibration damping standoffs was a huge help. Additionally, when I cover the vent slots on the chassis, the preamp has no issues with microphony whatsoever. It is a very impressive preamp at that point with smooth and clear sound. In my system, 9.5V is just right.
I wonder if ClaudeG’s combination of film caps and the Tocos Cosmos volume pot is providing the improved bass weight and detail.
For now, the stock Completion Kit components and chassis are great. The only thing I would change with the chassis is to go with top and bottom chassis cover plates without the ventilation slots. I think I have a sensitive microphonic Korg NuTube, and mounting the PCB on the vibration damping standoffs was a huge help. Additionally, when I cover the vent slots on the chassis, the preamp has no issues with microphony whatsoever. It is a very impressive preamp at that point with smooth and clear sound. In my system, 9.5V is just right.
Hi Rich,
Great, please let us know your findings... is there anything you can arrange regarding the cap in the signal path that is in the middle, shouldn't be too difficult to address that one aswell?
Regarding my findings posted back then, replacing only the 1st and 2nd cap in the signal path (at that stage, before going PPP for all 3 x 2 = 6 of them) while the TOCOS was already in:
And here are the result :
- The PPP caps didn’t alter the sound in terms of sonic balance, caracter, frequencies… it is all nearly the same, but even better !
- The PPP caps definitely added even more kick and extended bottom frequencies, the extra kick not being a problem as all remained balanced and in fact more differentiated between bass notes
- the PPP caps outlined another dimension in terms of precision, « grain » / resolution, both opening a curtain in transparency while also taking a slight veil out
- All frequencies seem better balanced, no more of the slight mid-bass exageration
- It all sounds very pure but also flows much better, intergration of music is better, making a very enjoyable whole – so addictive I must say that carrying listening tests is difficult, you get carried away !
- Frequency range seems a bit extended, deepest bass being now clearly as well representated than the other frequencies, both energic and subtle, I also believe that the highest treble is a bit better
- Noise floor seems lower, lowest sounds more natural, easier to follow and better integrated
So it might indeed be your hypothesis could be right re Tocos + PPP caps combo, but then I don't want to bias you before you carry your independant listening tests.
Just for note, I adjusted my favourite voltage also indeed after all the mods I did
Good luck tweaking further an already excellent unit
Claude
Great, please let us know your findings... is there anything you can arrange regarding the cap in the signal path that is in the middle, shouldn't be too difficult to address that one aswell?
Regarding my findings posted back then, replacing only the 1st and 2nd cap in the signal path (at that stage, before going PPP for all 3 x 2 = 6 of them) while the TOCOS was already in:
And here are the result :
- The PPP caps didn’t alter the sound in terms of sonic balance, caracter, frequencies… it is all nearly the same, but even better !
- The PPP caps definitely added even more kick and extended bottom frequencies, the extra kick not being a problem as all remained balanced and in fact more differentiated between bass notes
- the PPP caps outlined another dimension in terms of precision, « grain » / resolution, both opening a curtain in transparency while also taking a slight veil out
- All frequencies seem better balanced, no more of the slight mid-bass exageration
- It all sounds very pure but also flows much better, intergration of music is better, making a very enjoyable whole – so addictive I must say that carrying listening tests is difficult, you get carried away !
- Frequency range seems a bit extended, deepest bass being now clearly as well representated than the other frequencies, both energic and subtle, I also believe that the highest treble is a bit better
- Noise floor seems lower, lowest sounds more natural, easier to follow and better integrated
So it might indeed be your hypothesis could be right re Tocos + PPP caps combo, but then I don't want to bias you before you carry your independant listening tests.
Just for note, I adjusted my favourite voltage also indeed after all the mods I did
Good luck tweaking further an already excellent unit
Claude
Thanks for the suggestions. I left my B1 Korg NuTube with a buddy in California after attending the recent Burning Amp Festival. My friend is just blown away with how this preamp sounds in his system. I think ClaudeG’s tweaks will extract extra performance from the preamp. Can’t wait to get it back to install all the caps and volume pot. The 1U chassis will force me to be a little more creative in fitting the 1uF caps.
After months of waiting for powder coating (long story), I am ready to complete my amplifier. It's been a while since I last touched it. I am looking for some advice on setting up the voltage divider portion (mine is a hybrid amplifier with no volume control).
For testing, I hooked up a 50K pot (backwards) and determined the maximum volume occurs at the 35K/15K split. I bought some 15K and 34K resistors. Logically I would assume the 15K is R1 and 34K is R2. Is that correct? Also does it matter where I ground R2?
