[Boban]

Hi there,

this days I will buy AKSA 55N+ kit from Hugh but I don't have enough $ to buy and GK-1. Need to choose some DIY preamp. I know that AKSA have enough gain, but I need preamp. Anybody here try any DIY preamp with AKSA 55? Or should I use some buffer circuit??? Discrete or tube preamp/buffer? Any ideas?

What U think about this JFET buffer (left from 4.7uF):



Thinking to use it like preamp with AKSA. The sound is excellent! I try it with my LM3875 gainclone.

BTW, what u think about AKSA 55 and Aleph P 1.7 preamp relation?

Thanks to all

[CButterworth]

Boban,

I have had the same dilema myself.  I have used the AKSA 55N for around three years (maybe more).  I am saving my cash to upgrade to the the LifeForce.  However, I want a tubed preamp and cannot afford the GK-1.

After various recommendations, I have settled on building the Aikido preamp.  The design is incredibly versatile.  I hooked one up to my AKSA last weekend, the gain was around x30 which is huge in relation to the GK-1.  Anyway, it sounded great and with a 100K volume pot on the preamp, volume adjustment was not difficult at all.

I plan on building the Aikido using 6sn7 tubes which will yield a gain of around x10.  I bought boards from the designer - John Broskie at www.tubecad.com.

Anyway, I am sure the Hugh's GK-1 sounds excellent, afterall his designs and products are World Class.  Having said that, designing the PSU and figuring out tube combinations has been a real learning experience for me.

Regards,
Charlie

[fajimr]

boban

This might help you in your choice.... I currently have my CDP running directly into my 55N+ with some external volume attenuators and the sound is wonderful!  Not sure if you want switching capabilities too but a simple passive device might be all that you need. cheers jim

[Boban]

Thanks, but I need more inputs. I have CD6000 using like a transport and TDA1541A Non O/S DAC.

Boban

[fajimr]

Thanks, but I need more inputs.

hi boban

been there, too    should have given this with my last post...  http://www.audiocircle.com/index.php?topic=31272.0
(I ended up with the selector switch that peter PSP suggested although haven't wired it up yet)

I know I am not addressing your question directly, just throwing out options.  i'll let the heavies weigh in on technical commentary

[AKSA]

Hi Boban,

If you are the guy on DIYaudio whose circuit I looked at recently, then you are 1 smart cookie, welcome to our forum!

Your buffer is elegant, I like it.  It would be very low distortion, AND it's open loop so they are all low order.  This would sound very good.  You might protect the input with a zener, however, as fet gates are very fragile, and a shunt volume control would greatly reduce the inevitable distortion which takes place at the wiper.

As NP puts it, 'If you want it to sound like a tube, use a tube'.  Not even a fet will sound as good.  This is the reason I go to a lot of trouble in the GK1 to use a tube, with all the difficulties of power supply, filament, and mounting the socket.  The tube adds something special to the music which for better or worse is referred to as 'warmth', but it's very, very difficult to imitate this sound with SS electronics.

But, as you remark, it's expensive.  A cheap option is a fet circuit, and it can be run off low voltage, which is always convenient.

I've always believed in SS power amplifiers and tube pres - it's a more satisfactory solution than a tube power amp and a SS pre, and often you find that an all tube system has just a bit too much 'warmth', which can obscure musical detail.  And of the tube configurations, I like the cathode follower, because for the same operating point the CF has around 5/32 (16%) of the distortion of the plate loaded configuration (according to Langford Smith in Radiotron Tube Manual).

Thank you for your contribution,

Cheers,

Hugh

[PeterM]

No offense intended 

Just in case it does not get mentioned but that circuit was designed by Pedja Rogic 3 years ago http://www.pedjarogic.com/gc/index.html

I know there is no claim to fame here on this circuit but the record needs to be set straight, Pedja is a very astute and tuned guy in audio design.

[AKSA]

Thanks Peter,

Fascinating site.  I like this guy, he is indeed very astute and seems to have an affinity with the subjective aspects of recorded music.  I get very distracted when I see obsessive documentation of distortion measurements;  it's important, but the complexities of human perception of distortion make the actual spectrum of distribution more important than the THD.  The gear required to actually reveal the proper spectrum is expensive and tricky to drive (and necessarily deals with single tone inputs anyway, far removed from music), and in the final analysis, the market speaks on the basis of how it stacks up subjectively.  Any designer who ignores the market, and in particularly the tube market and the mass perceptions of warmth and 'organic' sound, is missing the point, usually for reasons of purist dogma.


Cheers,

Hugh