Hi All ,
My B1K is up and running and after thoroughly testing it with cheap amplified speakers I did put it in my main system ( Nagra Classic Amp and Martin Logan Montis speakers ) .
I have a very hard time finding a good sounding tube preamp at a reasonable cost and this why I went the DIY way with the B1K .
I am not disappointed this little preamp is really sounding very well . Previously I was using a passive HATTOR preamp which is good too but the B1K brings flesh and body to the music even though it is a little bit less transparent than the passive preamp .
I have used the PPP caps Claude recommended , they will require quite a few hours of burn in ... even though with no burn in the sound was already very good .
I intend to do a couple of upgrade :
- Better PSU , going for an AMD sigma 11
- Going for a TKD potentiometer ( now it is just the blue alps ) , which kind of sound quality improvement I can expect from a better potentiometer ?
The gain of the preamp is a little too much for my system , I can use the potentiometer only to the position 9 oclock . Is there a simple way to reduce gain without degrading sound quality. ?
Does going for a 100K potentiometer instead of 50 K is a good idea ?
Cheers .
My B1K is up and running and after thoroughly testing it with cheap amplified speakers I did put it in my main system ( Nagra Classic Amp and Martin Logan Montis speakers ) .
I have a very hard time finding a good sounding tube preamp at a reasonable cost and this why I went the DIY way with the B1K .
I am not disappointed this little preamp is really sounding very well . Previously I was using a passive HATTOR preamp which is good too but the B1K brings flesh and body to the music even though it is a little bit less transparent than the passive preamp .
I have used the PPP caps Claude recommended , they will require quite a few hours of burn in ... even though with no burn in the sound was already very good .
I intend to do a couple of upgrade :
- Better PSU , going for an AMD sigma 11
- Going for a TKD potentiometer ( now it is just the blue alps ) , which kind of sound quality improvement I can expect from a better potentiometer ?
The gain of the preamp is a little too much for my system , I can use the potentiometer only to the position 9 oclock . Is there a simple way to reduce gain without degrading sound quality. ?
Does going for a 100K potentiometer instead of 50 K is a good idea ?
Cheers .
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This circuit is based on the application notes from Korg. This document includes information about how to alter the gain.
However, NP selected the gain structure for a specific harmonics profile with 1Vrms across the output. If you alter the gain structure or output voltage, you working outside of the operating parameters he specified.
Not meant to dissuade you. Just a cautionary note - you may need to do some experimenting to get the sound you want.
However, NP selected the gain structure for a specific harmonics profile with 1Vrms across the output. If you alter the gain structure or output voltage, you working outside of the operating parameters he specified.
Not meant to dissuade you. Just a cautionary note - you may need to do some experimenting to get the sound you want.
Sigma 11 is better.. But.. Take out part of the crc in front. More benefit. Or the filter will actually makes it sound more similar
I agree is a better value and more . . Yes its more musical and does more than the single ended triode tube preamp. Very dht like actually.
Tkd... Tried its more detailed and less body . Depending what you need..
I agree is a better value and more . . Yes its more musical and does more than the single ended triode tube preamp. Very dht like actually.
Tkd... Tried its more detailed and less body . Depending what you need..
Hi,
Really glad you are happy with your preamp (didn't doubt about it) and yes indeed, the sound will further improve while the caps burn-in... allow a bit of time, say a week of burning-in gives you probably already near end result, while 24h gives already a good idea.
Regarding transparency, you may find that the Alps Blue is robbing quite some "details" and also 3D from the soundstage. At least these are my findings, I am not a big fan of these but do love the Alps Black Beauty (discontinued) and found the Tocos Cosmos to be incredible both in absolute terms and also for the money (less than 10$!). See my posts / reports here - as many others who tried the Tocos or other good pots, indeed the volume potentiometer makes quite a difference!
If you own already one of the large sized TKD potentiometers (these are in the 70E bracket I believe), then you can IMHO go for it as it has only positive feedbacks. If you don't own already one, then you may want to consider aswell the Tocos Cosmos. Far cheaper and seems to stand against it. My own unit sounded very close to "direct sound through an air wired quality resistor network" I compared to. I have though not tested the Muse electronic volume control Papa is using but would love to as that could potentialy be the ultimate step... one day perhaps
Regarding your gain question "is going for a 100K potentiometer instead of 50 K a good idea", I am afraid you don't fully understand how a potentiometer work. That has nothing to do with gain, the pot is a divider and functions as a ratio, so whatever "K value" you chose it is only affecting the input and output impedance the circuit sees (and to a small extend the background noise)... not gain or volume adjustability. So the "K" is in that case choosen by the output impedance of your source...
Regarding "Is there a simple way to reduce gain without degrading sound quality?"... I have been there, and IMHO the short answer as of today is NO. That little beauty is indeed "frustrating on the paper", with all its caps in the signal path (LOL) and gain that can't be really used as you want to stay below 2V IMHO re distorsion, whatever your trim pot position. But that little beauty sounds that nice because Papa decided that with a gain of 16dB it got the right sonic enveloppe / characteristics, so the gain is intrinsic to its sonic signature. Of course you could easily alter the gain, but that would change the sound. Not recommended - Papa's harmonic signature would probably be mostly gone.
Last but not least, let us know your findings with AMD sigma 11 !
What PS supply are you using currently and have you upgraded the PS caps on the board?
Results with different PS are quite variable on the forum (perhaps also because people had different starting points than the PS Papa recommened). As said, upgrading didn't make a clear cut so far for me, but glad to improve further!
Have even more fun and thanks for your detailled feedback
Claude
Really glad you are happy with your preamp (didn't doubt about it) and yes indeed, the sound will further improve while the caps burn-in... allow a bit of time, say a week of burning-in gives you probably already near end result, while 24h gives already a good idea.
Regarding transparency, you may find that the Alps Blue is robbing quite some "details" and also 3D from the soundstage. At least these are my findings, I am not a big fan of these but do love the Alps Black Beauty (discontinued) and found the Tocos Cosmos to be incredible both in absolute terms and also for the money (less than 10$!). See my posts / reports here - as many others who tried the Tocos or other good pots, indeed the volume potentiometer makes quite a difference!
If you own already one of the large sized TKD potentiometers (these are in the 70E bracket I believe), then you can IMHO go for it as it has only positive feedbacks. If you don't own already one, then you may want to consider aswell the Tocos Cosmos. Far cheaper and seems to stand against it. My own unit sounded very close to "direct sound through an air wired quality resistor network" I compared to. I have though not tested the Muse electronic volume control Papa is using but would love to as that could potentialy be the ultimate step... one day perhaps
Regarding your gain question "is going for a 100K potentiometer instead of 50 K a good idea", I am afraid you don't fully understand how a potentiometer work. That has nothing to do with gain, the pot is a divider and functions as a ratio, so whatever "K value" you chose it is only affecting the input and output impedance the circuit sees (and to a small extend the background noise)... not gain or volume adjustability. So the "K" is in that case choosen by the output impedance of your source...
Regarding "Is there a simple way to reduce gain without degrading sound quality?"... I have been there, and IMHO the short answer as of today is NO. That little beauty is indeed "frustrating on the paper", with all its caps in the signal path (LOL) and gain that can't be really used as you want to stay below 2V IMHO re distorsion, whatever your trim pot position. But that little beauty sounds that nice because Papa decided that with a gain of 16dB it got the right sonic enveloppe / characteristics, so the gain is intrinsic to its sonic signature. Of course you could easily alter the gain, but that would change the sound. Not recommended - Papa's harmonic signature would probably be mostly gone.
Last but not least, let us know your findings with AMD sigma 11 !
What PS supply are you using currently and have you upgraded the PS caps on the board?
Results with different PS are quite variable on the forum (perhaps also because people had different starting points than the PS Papa recommened). As said, upgrading didn't make a clear cut so far for me, but glad to improve further!
Have even more fun and thanks for your detailled feedback
Claude
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Thank for all the answers , I understand it is better to not mess with the gain of this nice little preamp .
Claude ,
Thank's for your detailed reply .
I will probably go for the TKD pot as I want to have the motorized version to be able to remotely control the volume .
The shortcoming that you attribute to the ALPS "Alps Blue is robbing quite some "details" and also 3D from the soundstage" is in fact what I felt I was somewhat missing when compared to my passive preamp .
Even with the ALPS the sound was already very good .
A potentiometer is in fact a very critical piece of equipment in a preamp .
You are right I am no expert in electronic and do not necessary understands the details of electronic . My source is the line output of my Audiomat Maestro 3 DAC . I did pick up 50 KOhm as it is usually the standard input impedance for electronic preamp .
I will let you know the results with the sigma 11 , I have all the parts but have been waiting to receive the boards from the state for almost 3 weeks ... The PSU I am using now is the same Meanwell wall wart PSU that you are using I think . I took the reference from one of your post.
I am using the standard Nichicon caps as recommended by Pa .
Thank's Pa for this Wonderfull little preamp and also how to calculate the resistor on the output to reduce voltage ...
One simpler thing I may be doing , there is two input sensitivity n the Nagra amplifier 1V or 2V .
I have kept 1V as it is supposed to sound better. . I will test it also at 2V .
Audiophile life is really fun with DIY projects .
Claude ,
Thank's for your detailed reply .
I will probably go for the TKD pot as I want to have the motorized version to be able to remotely control the volume .
The shortcoming that you attribute to the ALPS "Alps Blue is robbing quite some "details" and also 3D from the soundstage" is in fact what I felt I was somewhat missing when compared to my passive preamp .
Even with the ALPS the sound was already very good .
A potentiometer is in fact a very critical piece of equipment in a preamp .
You are right I am no expert in electronic and do not necessary understands the details of electronic . My source is the line output of my Audiomat Maestro 3 DAC . I did pick up 50 KOhm as it is usually the standard input impedance for electronic preamp .
I will let you know the results with the sigma 11 , I have all the parts but have been waiting to receive the boards from the state for almost 3 weeks ... The PSU I am using now is the same Meanwell wall wart PSU that you are using I think . I took the reference from one of your post.
I am using the standard Nichicon caps as recommended by Pa .
Thank's Pa for this Wonderfull little preamp and also how to calculate the resistor on the output to reduce voltage ...
One simpler thing I may be doing , there is two input sensitivity n the Nagra amplifier 1V or 2V .
I have kept 1V as it is supposed to sound better. . I will test it also at 2V .
Audiophile life is really fun with DIY projects .
You 're welcome
I guess you are refering to the TDK 2CP-2511 MC pot, which is a good pot indeed, albeit quite at a price. For sure you should improve on the Alps as you presumed, moving towards what you are currently missing. Pity Tocos doesn't do any motorized version... I find the Tocos' 3D soundstage and precision are addictive.
The TDK you mentioned comes in various impedances, from 10k to 100K. It is sad Audiomat doesn't seem to communicate on the ouput impedance of its Maestro 3 DAC. It looks like a serious DAC so indeed the 50 kOhm pot you picked up is a safe bet for now... and the future "in case of". Note you could probably have gone for 20k (or even less but that could bring other probs IMHO for dubious gains), but well, not sure the background noise is really that much lower in real life and really worth the risk.
Regarding PS, yep I still use the one I posted about, which is basicaly Papa's version for Eu, but a slightly upgraded series with lower ripple. As you may already have noticed, I tried later upgrading the PS caps from 1000 to 2200uF and that brought a small improvement, but not that much. A traditional quality lab PS, 50x the size of the walwart LOL, brought a slightly different sound especialy in the bass, but "all in all" I prefered it original. There were small differences though, taste and coulours around PS variations... yes please let us know your findings with your PS!
Enjoy tweaking
Claude
I guess you are refering to the TDK 2CP-2511 MC pot, which is a good pot indeed, albeit quite at a price. For sure you should improve on the Alps as you presumed, moving towards what you are currently missing. Pity Tocos doesn't do any motorized version... I find the Tocos' 3D soundstage and precision are addictive.
The TDK you mentioned comes in various impedances, from 10k to 100K. It is sad Audiomat doesn't seem to communicate on the ouput impedance of its Maestro 3 DAC. It looks like a serious DAC so indeed the 50 kOhm pot you picked up is a safe bet for now... and the future "in case of". Note you could probably have gone for 20k (or even less but that could bring other probs IMHO for dubious gains), but well, not sure the background noise is really that much lower in real life and really worth the risk.
Regarding PS, yep I still use the one I posted about, which is basicaly Papa's version for Eu, but a slightly upgraded series with lower ripple. As you may already have noticed, I tried later upgrading the PS caps from 1000 to 2200uF and that brought a small improvement, but not that much. A traditional quality lab PS, 50x the size of the walwart LOL, brought a slightly different sound especialy in the bass, but "all in all" I prefered it original. There were small differences though, taste and coulours around PS variations... yes please let us know your findings with your PS!
Enjoy tweaking
Claude
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Yes I am referring to the TKD 2CP-2511 , they are expensive but I think this nice little preamp desserves it .
I have asked Audiomat for the output impedance of my maestro dac .
What will be the benefit if I could go to a lower potentiometer value like 20k ?
For ps , I will definitely report sound quality improvement if there is . Eagerly waiting these boards from amb.
The preamp is now in 24 hours burn in in the basement ... it is amazing as this device is generating no heat at all , quite a break from the audio equipment I am used to .
I have asked Audiomat for the output impedance of my maestro dac .
What will be the benefit if I could go to a lower potentiometer value like 20k ?
For ps , I will definitely report sound quality improvement if there is . Eagerly waiting these boards from amb.
The preamp is now in 24 hours burn in in the basement ... it is amazing as this device is generating no heat at all , quite a break from the audio equipment I am used to .
Hi Jean-Michel,
in short: lower inherent noise.
Potentiometer as every resistor generate a noise (see Johnson noise), the higher the value the more, so going 20k instead of 50k or 100k (which are for that noise quite relevant values) should potentialy give you less background noise. Well, although I am not convinced that at one can really hear it at that level or that the the Nutube doesn't dominate anyway the sonic signature, but in theory all little bits add up and given the choice why not going for the best option straight away?
Having said that, if you hear more details and have a 3D soundstage, it will be mainly due to the pot quality, not its lower value, but as said it all adds up...
Bon montage
Claude
in short: lower inherent noise.
Potentiometer as every resistor generate a noise (see Johnson noise), the higher the value the more, so going 20k instead of 50k or 100k (which are for that noise quite relevant values) should potentialy give you less background noise. Well, although I am not convinced that at one can really hear it at that level or that the the Nutube doesn't dominate anyway the sonic signature, but in theory all little bits add up and given the choice why not going for the best option straight away?
Having said that, if you hear more details and have a 3D soundstage, it will be mainly due to the pot quality, not its lower value, but as said it all adds up...
Bon montage
Claude
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Hello.
After the ALPS potentiometer supplied with the kit, I tried the Cosmos potentiometer and now the TKD 2CP-2511. the differences are extremely subtle when listening between each of these potentiometers. However I prefer the TKD especially because of his progressiveness which allows to measure much better the listening level, the channel balancing and especially the smoothness of the maniment especially in comparison with the ALPS potentiometer. The three potentiometers have the same value, ie 50 K Ohms.
If it helps ...
Gidu
After the ALPS potentiometer supplied with the kit, I tried the Cosmos potentiometer and now the TKD 2CP-2511. the differences are extremely subtle when listening between each of these potentiometers. However I prefer the TKD especially because of his progressiveness which allows to measure much better the listening level, the channel balancing and especially the smoothness of the maniment especially in comparison with the ALPS potentiometer. The three potentiometers have the same value, ie 50 K Ohms.
If it helps ...
Gidu
Hmm, if you really hear something that distinguishable I would rather look at grounding and route of the wires.
Is your pot connected to mass / housing? Is you unit inside a metal casing? Is this noise changing when you touch your housing or " touch or move" some cables inside?
Just thinking loud... applies to every kit... but if it is really very very low level and only there at full volume while no music, then it might be indeed tube or else
Claude
Is your pot connected to mass / housing? Is you unit inside a metal casing? Is this noise changing when you touch your housing or " touch or move" some cables inside?
Just thinking loud... applies to every kit... but if it is really very very low level and only there at full volume while no music, then it might be indeed tube or else
Claude
What I am hearing is very very low even at full volume with no music .
Yes pot is connected to ground and pot body is grounded and casing is full aluminium .
I do think it is probably the tube but it is so low that I do not think it is a problem , it is a little bit like white noise but extremely low and to what I have heard has no impact on the music .
Yes pot is connected to ground and pot body is grounded and casing is full aluminium .
I do think it is probably the tube but it is so low that I do not think it is a problem , it is a little bit like white noise but extremely low and to what I have heard has no impact on the music .
Hi Claude ,
I did got the answer from Audiomat , the output impedance of my DAC Maestro 3 is 110 Ohm which is low .
I can I think safely go the a 20 Kohm potentiometer on the preamp ?
An other question , I will probably in the future add a second input from a phono prepreamplifier .
Does 20Kohm will limit my choice of phono prepreamplifier or I am fairly safe ?
I did got the answer from Audiomat , the output impedance of my DAC Maestro 3 is 110 Ohm which is low .
I can I think safely go the a 20 Kohm potentiometer on the preamp ?
An other question , I will probably in the future add a second input from a phono prepreamplifier .
Does 20Kohm will limit my choice of phono prepreamplifier or I am fairly safe ?
Yes, you can safely go for 20k with your DAC.
20k is quite high already and should enable you to accept most units bare a few exotics with very / shamefull high output impedances.
A rule of the thomb says you are safe with reasonable cables and 10x less source output impedance, so 2k output impedance. I find that rule very conservative, on more usual lengths/low capacitive cables found in home HIFI you will still be safe with much higher impedances, and at very high ones you may start to lose treble response (nothing will blow, don't worry ;-)...
Claude
20k is quite high already and should enable you to accept most units bare a few exotics with very / shamefull high output impedances.
A rule of the thomb says you are safe with reasonable cables and 10x less source output impedance, so 2k output impedance. I find that rule very conservative, on more usual lengths/low capacitive cables found in home HIFI you will still be safe with much higher impedances, and at very high ones you may start to lose treble response (nothing will blow, don't worry ;-)...
Claude