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Super simple single stage tube preamp
http://diyaudioprojects.com/Forum/viewtopic.php?f=9&t=3266
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Author:  Grega [ 19 Dec 2011, 05:29 ]
Post subject:  Re: Super simple single stage tube preamp

tom - thats fantastic mate - work well done!

Author:  Suncalc [ 10 Jan 2012, 22:56 ]
Post subject:  Re: Super simple single stage tube preamp

For anyone tube rolling with this design, I've added another tube to the possibles list: the 12AV7. It's performance falls somewhere between the 12AU7 and 12AY7 for gain and it's distortion is excellent. Here is the new table with all the tubes so far.
Attachment:
USSS Performance Numbers.png

I hope this is of use.

Author:  tombethe [ 12 Jan 2012, 12:36 ]
Post subject:  Re: Super simple single stage tube preamp

Thanks a lot Matt!

BTW - the real life hit me again... Holidays are over and a lot of work is waiting now...
I'll post the layout update asap ;-).

Author:  tombethe [ 24 Jan 2012, 16:07 ]
Post subject:  Re: Super simple single stage tube preamp

Hey again,

here's the update for the board and the files for the DIY production.. I believe it is definitely final now (now - i hope so).
Attachment:
SSUP var out.png

Attachment:
comp_layout.pdf

Attachment:
copper_layout.pdf

Attachment:
SSSUP Partlist.pdf


PPS: Matt and Mark - i'll go to make one myself, but with EZ81 recified hybrid PSU (about 250VDC / -2V @ 6 - 7mA) and an JJ E88CC (low gain, 6.3 AC heater) as a frontend for my LM3886 stereo.
I think it is also suitable for the TDA or LM1875. If anyone has interests, just write it...

Author:  mwhouston [ 24 Jan 2012, 16:26 ]
Post subject:  Re: Super simple single stage tube preamp

tombethe: good work looks fab.

Author:  mwhouston [ 22 Feb 2012, 06:22 ]
Post subject:  Re: Super simple single stage tube preamp

When I swapped the Silver Dragon for Paris I found the gain from the phono stage insufficient when using the 4S Universal preamp. Paris has it's own 4S Universal preamp built in and I was to discover I had installed a 12AU7 in the preamp section. Paris has an extremely transparent mid-range which I think maybe related to the 12AU7. Keep reading.

I swapped my 4S tube preamp for my BoZSE to get more gain to play LPs. I lent the 4S Universal to a friend because I was upgrading a preamp I sold him the year before and he had no replacement. I just got the 4S preamp back and installed it with The Silver Dragon. I have since upgraded to a MC cart. with an Hiraga bipolar MC stage. Lots of gain now.

When I listened to large orchestra (on vinyl) and very large choirs the sound was mushy and distorted. The 4S preamps has the pot on the output so they have to be able to handle the full input. I checked the tube in the 4S (its been a while since I have seen it). It was a Gold Lion (gold pin) 12AX7. I checked what is in Paris to find a Gold Lion 12AU7. I started thinking Paris handled big orchestras and choirs without a problem, could it be the 12AU7? I swapped out the 12AX7 in the 4S tube preamp for the 12AU7.

Straight away the over sound got more transparent and when large choirs hit the high notes no more mush or distortion. The whole preamp (4S Universal) sounded much better. Now I think this was a big part of Paris's ability to produce detailed very transparent mids. It's all in the glass!

Author:  Suncalc [ 01 Sep 2012, 22:34 ]
Post subject:  Re: Super simple single stage tube preamp

It's funny how things get away from you. I first posted the design for the 4S Universal in this post on July 19th, 2011. Yet here it is September 1st, 2012 (13-1/2 months later) and I have yet to actually put one together. So today I started to do the layout required to put one together.

However, in keeping with my obstinate nature, mine will be a little bit different (and not so simple). I think it safe to say that Mark is the master of the simple back-to-back wall wart power supply design. I will however be doing something a little more traditional. I am putting the preamp in a Pomona 4226 aluminum enclosure complete with its own 120v driven power supply including a 6CA4 rectifier and choke filtering.

I started the layout today and as soon as I start to drill metal I'll post some pics and a schematic (mostly for the power supply). More to follow.

Author:  mwhouston [ 01 Sep 2012, 22:59 ]
Post subject:  Re: Super simple single stage tube preamp

I don't use any of my 4S preamps (I built 6) mainly because they just don't have enough gain for my lazy tube power amps. I only use the BoZSE (Pass BoZ with some tweaks in the PS). The Black was probably the best sounding but the Universal (also in Paris) was the most flexible. Works well in Paris too.

What I like about the AC wall wart and then second step-up tranni is by the time the AC gets through two lots of trannis it comes out pretty clean. I've even considered three passes!! Yes some photos when you have something to photograph.

Author:  Suncalc [ 02 Sep 2012, 12:53 ]
Post subject:  Re: Super simple single stage tube preamp

mwhouston wrote:
I don't use any of my 4S preamps (I built 6) mainly because they just don't have enough gain for my lazy tube power amps. I only use the BoZSE (Pass BoZ with some tweaks in the PS).
Wow! 34.6dB (-53.6 v/v) is not enough? How much gain are you getting out of those little FETs in the BoZSE?

Author:  mwhouston [ 02 Sep 2012, 16:52 ]
Post subject:  Re: Super simple single stage tube preamp

Suncalc wrote:
mwhouston wrote:
I don't use any of my 4S preamps (I built 6) mainly because they just don't have enough gain for my lazy tube power amps. I only use the BoZSE (Pass BoZ with some tweaks in the PS).
Wow! 34.6dB (-53.6 v/v) is not enough? How much gain are you getting out of those little FETs in the BoZSE?

From the fets I can get a 17V swing (into 10K I think from memmory). You are making me question my results but I can remember a number of times winding up the tube preamps and not being able to drive the power amps into clipping. With BoZSE I can.

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