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-   -   Hi Performance Pre amp (http://www.diyaudio.com/forums/tubes-valves/175328-hi-performance-pre-amp.html)

cjcc67 14th October 2010 01:38 AM

Hi Performance Pre amp
 
Greeting fellow DIYers.
After recently acquiring a LOMC cartridge i am using a battery powered head amp before my SRPP preamp .Thanks to Salas for his assistance. The current preamp is the Elektor project from the early 90's.
I thought it might be time to upgrade. I have seen Allen Wrights designs which look quite good. Are there any other high performance designs i should be considering.
I am looking to build both the phono and linestage into a single enclosure.
I am starting with a blank sheet although it would be nice to recycle the HV ( currently 350 & 310V) regulated power supplies from my existing project. The voltage can be lowered but not increased.
I look forward to your suggestions

807tubenut 14th October 2010 02:50 AM

I really dig the aikido


Aikido Amplifier Revisited


But I'm not qualified to make a suggestion past my ears.

cjcc67 15th October 2010 12:15 AM

Thanks 807
Did i post this question in the wrong forum?
I can see the bench riaa is possible for the phono but will not have enough gain

Eli Duttman 15th October 2010 02:12 AM

1 Attachment(s)
Allen Wright's hybrid cascode allows the use of a LOMC, without a SUT or "head" amp. AW has worked extensively with the 6922. However, that's not the only type that works in a hybrid cascode, with "sand" "downstairs" and a tube "upstairs". The 6GK5, a type I'm impressed by, is an excellent candidate too.

If you truly like your SS head amp, a tweaked version of RCA's "classic" passively equalized design should do nicely. The RCA circuit offers roughly 45 dB. of gain. I've uploaded the tweaked RCA schematic for your consideration.

cjcc67 5th November 2010 07:53 AM

Thanks Eli. Allens RTP3C looks good if not a little complex. It's on my shortlist along with the current akido/steve bench in another thread. I like the concept of the differential mode of the RTP3 as i'm considering to mate it with the KK 300BPP(P).
Has anybody built the RTP 3 or the KK 300b monos ?

Alex M 5th November 2010 03:36 PM

Quote:

Originally Posted by cjcc67 (Post 2354969)
Thanks Eli. Allens RTP3C looks good if not a little complex. It's on my shortlist along with the current akido/steve bench in another thread. I like the concept of the differential mode of the RTP3 as i'm considering to mate it with the KK 300BPP(P).
Has anybody built the RTP 3 or the KK 300b monos ?

I have a DIY RTP3 which I built from scratch.

I'm not sure what you mean by "KK 300b monos", but I have built Kevin Kennedy's push-pull 300B monoblocks, if that's any use to you...

Alex

cjcc67 5th November 2010 11:30 PM

Alex I saw your website. That's where I learnt about the monos. Your efforts have inspired me. Did you have a wiring diagram you used in addition to the schematic from the website?
Craig

Alex M 6th November 2010 05:05 PM

Hi Craig,

I would definitely recommend the push-pull 300B amp - it sounds great, it has worked flawlessly (apart from a couple of minor problems due to faulty valves) and its differential operation matches my RTP3 well. The only issue with this combination is gain - the RTP3 has a minimum line stage gain of about 10 (3dB), while the 300B amp has a differential gain of 26dB, which is on the borderline of being too high for my 90dB speakers.

No, the layout was entirely my own design, although I did take Kevin's advice to rotate the output transformers to reduce hum. If you decide to build this amp, I would be happy to give you a rough layout plan and a photo or two if that helps.

Alex

danFrank 6th November 2010 06:00 PM

Quote:

Originally Posted by Alex M (Post 2356287)
No, the layout was entirely my own design, although I did take Kevin's advice to rotate the output transformers to reduce hum. If you decide to build this amp, I would be happy to give you a rough layout plan and a photo or two if that helps.
Alex

Hi, Do you mind posting (or e-mailing me) your layout plan? I am especially interested in the correct orientation of the transformers. Are you using the Citation 2 outputs? I have been planning on building this amp for a long time. I think I would use a CF as the driver though as it would have more strength to drive the 300B's.
Thanks again, Daniel

Nounours18200 11th December 2010 06:17 PM

Quote:

, Do you mind posting (or e-mailing me) your layout plan?
Unless you prefer to keep your design confidential, -this can be understood-, I assume that many people on this forum might be interested by working on a preamp able to surpass the AR SP-11...

If you accept to share your knowledge and skematics, we would be happy !:)


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