Aspen Preamp
Thiago,
Here's one from 2002. I sold quite a few. This uses a SS gain block and tube cathode follower output, with Zout around 130R. Sounds very, very good.
In 2010 I redesigned the SS section to use a CFP with gain. It actually sounded much better.
Cheers,
Hugh
Thiago,
Here's one from 2002. I sold quite a few. This uses a SS gain block and tube cathode follower output, with Zout around 130R. Sounds very, very good.
In 2010 I redesigned the SS section to use a CFP with gain. It actually sounded much better.
Cheers,
Hugh
Attachments
VHex-Pre
Hello all!
Here is my view on the overall preamp solution, including the line stage with 12db gain and optional unity gain balanced line driver.
Note - it's very, very quiet. Noise is below any practical level - with the input shorted, you hear nothing (better than -110db).
The circuit is powered from +/-15V DC rails.
We will most likely come up with the layout for the whole thing pretty soon.
Cheers,
Valery
Hello all!
Here is my view on the overall preamp solution, including the line stage with 12db gain and optional unity gain balanced line driver.
Note - it's very, very quiet. Noise is below any practical level - with the input shorted, you hear nothing (better than -110db).
The circuit is powered from +/-15V DC rails.
We will most likely come up with the layout for the whole thing pretty soon.
Cheers,
Valery
Attachments
Hi Hugh,
I like the tube section.
I assume, V2 is buffering inverted signal for the balanced output, right?
Cheers,
Valery
Hi Valery,
Thank you so much for posting here.
What is your recommendation for PSU (shunt or LM78XX) for your pre-amp design, and can it be incorporated on the pre-amp PCB itself (if at all possible), so all that is required is a XFR to have a working pre.
regards
Prasi
edit: changed text as per underlined.
Last edited:
Hi Valery,
I might disappoint you!
No, this is unbalanced output. The inverter and CF is set up to compensate the high impedance B+ supply to ensure seggtrong bass output that was atypical for a tube. The tube was a variable frame grid 6ES8 which added extra H2 / H3 for a cathode follower.
HD
I might disappoint you!
No, this is unbalanced output. The inverter and CF is set up to compensate the high impedance B+ supply to ensure seggtrong bass output that was atypical for a tube. The tube was a variable frame grid 6ES8 which added extra H2 / H3 for a cathode follower.
HD
Hi Valery,
I noticed big 220u elco's on outputs. Is this necessary or can we bypass and go DC? Or maybe out good 1uF film cap bypass?
I noticed big 220u elco's on outputs. Is this necessary or can we bypass and go DC? Or maybe out good 1uF film cap bypass?
Hi Valery,
I noticed big 220u elco's on outputs. Is this necessary or can we bypass and go DC? Or maybe out good 1uF film cap bypass?
Hi X,
Right, I have included them just to have some DC blocking in general.
However, assuming you've got the caps at the power amp's input, you can go DC.
This has become one of my favorite threads. It would he good to see real hardware built soon though. Some of these designs are so simple should be easy.
Hi Valery,
This looks like the revised Ampliwire with the op-amp balanced circuit added to it.
Is this correct?
Thanks.
Thanks for posting these.
Nice and reasonably simple designs, but the BF244Cs are no more.
I have made yesterday a simple preamp. A bit similar to marantz PM7000 front end or the AD797 OPamp. The ADPreamp is very simple, performance is good to. It is dead quiet at idlle. I have measured it with 1k load and didn't blow up 😀. The modulated 3kHz 4kHz and 5kHz doesn't show any IMD products (only my crappy psu noise).
With two mosfets at the back or BD's could create a nice headamp.
I have shorted the NFB cap and the offset was about 5mV, so with a bit of the work it can be done a full DC coupled (I hope anyway).
Regards Pit
With two mosfets at the back or BD's could create a nice headamp.
I have shorted the NFB cap and the offset was about 5mV, so with a bit of the work it can be done a full DC coupled (I hope anyway).
Regards Pit
Attachments
Last edited:
SR PP8 pcb for this and SR PP12 is in thread: http://www.diyaudio.com/forums/solid-state/173462-studio-reference-amplifier-180.html#post4191990
Attachments
Thank Mile
Tell me please, from experience which preamp topology adds more ''flawour'' to the sound ?
Regards
Peter
Tell me please, from experience which preamp topology adds more ''flawour'' to the sound ?
Regards
Peter
I like the SR PP8 Mile; it has bandwidth. This also puts the high pole so high that compensation is trivial. I believe it is a emitter drive version of the 1972 Hitachi AN for lateral fets. I have heard this in a power amp and it's very good, with very little phase shift.
Congratulations! Like many of your designs, it is both elegant and simple.
Hugh
Congratulations! Like many of your designs, it is both elegant and simple.
Hugh