B1 Buffer Preamp

[sandbasser]

Tread PSU OK?

I've got my B1 board and chips (thanks to Colin at PassLabs!!!)... I've got the parts on order. I got the AXON caps from a seller on eBay (audiograde).

But, I'm wondering about PSU. I have a Tread (from TangentSoft) that I'm not using for anything else. Will it work OK in B1???

NOTE: I saw some discussion on PSUs a few pages back and searched the forum and found nothing... So, please the noobie dumb question.

Thanks,

 

[troystg]

Re: Tread PSU OK?

I've got my B1 board and chips (thanks to Colin at PassLabs!!!)... I've got the parts on order. I got the AXON caps from a seller on eBay (audiograde).

But, I'm wondering about PSU. I have a Tread (from TangentSoft) that I'm not using for anything else. Will it work OK in B1???

NOTE: I saw some discussion on PSUs a few pages back and searched the forum and found nothing... So, please the noobie dumb question.

Thanks,

If it is 18 - 24 DC it should be fine. Mr. Pass said he used "higher" voltages than the "stated" 18 VDC so I would feel safe assuming anywhere between 18 and 24 would be good.

I still have PLENTY of 48VDC power supplies if anyone is interested in making regulated 24 or even 18 V pwr supplies.

Last count I had ~50 of them.. I just can't find the heart to throw them away....

 

[Salas]

I have found +/- 10V to be optimum subjectively in my non coupling caps version. I have started from +/- 8V, gone up to +/- 15V. It will not be surprising for +20V to be so for the normal version too. Just listen to voltages between 18-24V if possible.
I attach an FFT of my version at half volume knob rotation. Some high frequency minute spikes are present in my card's loop too.
Input=1VRMS=0dB.

 

[Nelson Pass]

I have found +/- 10V to be optimum subjectively in my non coupling caps version. I have started from +/- 8V, gone up to +/- 15V. It will not be surprising for +20V to be so for the normal version too. Just listen to voltages between 18-24V if possible.

For every JFET circuit like this, signal level and load there is a "sweet
spot" of rail voltage value. It is easy to find if you have a distortion
analyzer.

 

[crt]

Halo
i have finished build B1 buffer. Not Tested Yet.

B-1 Buffer picture

BUT i have a big problem.
the transformator i have buy is not 0-24V but only 0-14V.
after diode (rectifier) the voltage is 19,XX V
and after LM317 reg. the voltage MAX only at 18,3V.

can i use a lower voltage than a suggested (18-24V) ?
maybe around 15V or 17 V ?
with this lower value, should i change the another component maybe resistor value. because i can not buy another transformator again.
i will stick on this transformator

Thank's
La Ode

Sorry for poor english

 

[jean-paul]

Nice PCB but just a question: are the input and output caps not too close to eachother ? Or it could be that the yellow ones are input caps ?!

BTW You could have omitted input/output caps if you would have used the schematic of Salas ( symmetric B1 ).

 

[Melon Head]

Regarding your transformer.
Why not try a Notebook switchmode powersupply (ie most are 19.6 V). If it is good enough for Nelson's retail product, then it is definitely good enough for me.
Anyway go ahead and try the transformer, and if you have any doubts about the sound quality after listening to it, then try the external switch mode power supply and compare.

Anyway, I think nelson originally specified 18V, so I don't see a huge problem.

 

[Nelson Pass]

No, it's not a problem. Switchers work fine if you use the passive RC
filter in the project and the ferrite collar on the supply wire so that residual
noise doesn't make it to the FETs.

 

[crt]

Nice PCB but just a question: are the input and output caps not too close to eachother ? Or it could be that the yellow ones are input caps ?!

BTW You could have omitted input/output caps if you would have used the schematic of Salas ( symmetric B1 ).

yes maybe thats caps to close, but i think it will not make any problem. the yellow caps for input and parallel 3x 3u3 (red WIMA) for 10uF for output.

i use ariginnal Article in B-1 Buffer. can i remove the caps ?
salas version ?
sorry this is the first time i posted in Pass Labs discussion.

Regarding your transformer.
Why not try a Notebook switchmode powersupply (ie most are 19.6 V). If it is good enough for Nelson's retail product, then it is definitely good enough for me.
Anyway go ahead and try the transformer, and if you have any doubts about the sound quality after listening to it, then try the external switch mode power supply and compare.

Anyway, I think nelson originally specified 18V, so I don't see a huge problem.

I buy this transformer is "second hand" not new tranformator.
i though this is 24 V but i was wrong.

the notebook PS is quite expensive to me.
with those transformer only take US$ 3.

No, it's not a problem. Switchers work fine if you use the passive RC
filter in the project and the ferrite collar on the supply wire so that residual
noise doesn't make it to the FETs.

So, I will stick with 18 V.

Have Tested today. and no problemo.
SOUND , ABSOLUTELY SUPERB FOR ME !!!

THANK"S NELSON PASS! for your design.

Regards
La Ode

 

[Melon Head]

Great to see you have finished.
I am still casing mine up.

 

[crt]

yes, because this buffer is simple enough for newbie like me.
it take around 3 hours to build from scratch.

Power UP --> NO PROBLEM --> listen some my favorite song (ROCK LINE!)

Result is super amazing, for super cheap buffer.
it take less than US$ 30 for all the parts + PCB + Trasformator.

i will build a casing for this buffer next time i go back to home in Celebes (South East Sulawesi).
because right now i'm still study in Surabaya (East Java).

 

[Diomedian]

Regulator

I'm building my B1 on a wimpy patterned vector board (Vector 4614), and after laying out all the parts on it, I seem to have some space left. So I thought I'd try to put a simple voltage regulator on it.

I settled on the Sulzer regulator because the part count is low and it should be able to fit, but I'm not completely sure if I can get it to work. Two questions:
1) Is there a good replacement available for the 2n3053 originally used in this application?

2) Newer regulators since then seem to use the D44H11, but this part is very high current gain. Since the B1 only draws 20mA, and the hfe of the D44H11 is 60 or more, is it appropriate?

For reference, the schematic I'm looking at is here:
http://www.alw.audio.dsl.pipex.com/sulzer_circuit.htm

thanks in advance,
-j

 

[jean-paul]

I use the original article about the B-1 buffer. Can I remove the caps ?
salas version ?

No you can't with the original schematic but you can with Salas' version. Please see post #466.

 

[crt]

No you can't with the original schematic but you can with Salas' version. Please see post #466.

Thank's jean-paul

interesting one! more simple with no input/output caps, but have a relay's. for what ?
can i remove this relays if i want to build this version ?
is there worth to build this salas version ? different sound ?

Many Thank's
La Ode

 

[Salas]

I put the relay there just to avoid possibilities of thumping sounds if turning on the B1 while the main amp is on. Not essential, you can skip it, but do the classic procedure of turning on main amp last, turning it off first. The sound will miss any coupling capacitors signatures, so that will be its difference from a standard B1.

 

[crt]

I put the relay there just to avoid possibilities of thumping sounds if turning on the B1 while the main amp is on. Not essential, you can skip it, but do the classic procedure of turning on main amp last, turning it off first. The sound will miss any coupling capacitors signatures, so that will be its difference from a standard B1.

OK Salas, Thank's
Look's like i will build this one too.
but i will skip the relays, because my amp have a delay time potector too. and will make this buffer more more simple.

10-20V ? what voltage are you using ?
in schematic i see resistor near 7812 wrote 10 bleeter ? what that's mean ?

Thanks
La Ode

 

[Salas]

+/- 10V is the best sounding voltage point I have finally chosen.

That ''bleeder'' resistor is to help discharge the timing circuit. The 7812 is powering that circuit. You will have to omit all that part. Only use the 1Meg resistors to ground. Also try 220R gate stoppers and 220R output series resistors if you can attach them directly to the Jfets. It will sound more dynamic.
The concept in brief is as in the attachment.

 

[crt]

+/- 10V is the best sounding voltage point I have finally chosen.

That ''bleeder'' resistor is to help discharge the timing circuit. The 7812 is powering that circuit. You will have to omit all that part. Only use the 1Meg resistors to ground. Also try 220R gate stoppers and 220R output series resistors if you can attach them directly to the Jfets. It will sound more dynamic.
The concept in brief is as in the attachment.

can i use a little bigger value of pot. for volume control (25K)?
i use stepped attenuator (ladder type).

and what maximum v in input ? can 2V input?

Yeah, that's better schematic picture.
Terimakasih Banyak = Thank's A Lot Salas

I will repot if i have finish this one.
La Ode

 

[Salas]

Yes you can use 25k, only make the wiper to ground resistor 270k-330k. Don't omit that resistor! Strong DC will show up at output when switching the step attenuator if without that shunt resistor.

6VRMS input it can handle if with +/- 10VDC PSUs.

Good luck, I hope you will like it. Report your news.

 

[crt]

Yes you can use 25k, only make the wiper to ground resistor 270k-330k. Don't omit that resistor! Strong DC will show up at output when switching the step attenuator if without that shunt resistor.

6VRMS input it can handle if with +/- 10VDC PSUs.

Good luck, I hope you will like it. Report your news.

and for R1 = 220K still in use ?
270K-330K ? where i put this resistor ? can you draw me a simple schematic please.

Today i have replace the old 25K stepped attennuator with 22K value.
recalculate all the resistor again, that's pain but FUN!