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Old 8th September 2006, 10:22 AM   #61
MIKET is offline MIKET  United States
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Default Interesting

Doug L said "I was doing a paper design inspired by your requirements:
CSS loaded ECC99 with an EDCOR 10k:600 interstage transformer parafead between Cathode and Plate (Anode).
Current tentatively set to about 10 Ma"
I am interested in how this turns out.
I will pursue the 6C45Pi for now since I have a few in my tube stock.
Another possiblity might be a 12B4, it has a gain of about 7 but could improve with a transformer in front of it. I was thinking possibly something like this Jensen 1:1.4 transformer:
http://www.jensen-transformers.com/datashts/11p41.pdf
Its a bit pricey but very nice specs.
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Old 8th September 2006, 04:26 PM   #62
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What about something like this?

http://home.pacifier.com/~gpimm/Acti...t_control.html

http://home.pacifier.com/~gpimm/26_b..._linestage.gif

http://home.pacifier.com/~gpimm/
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Old 8th September 2006, 08:50 PM   #63
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Forget about the tube buffered LM3875 approach. Its not the buffer he uses in his commercial project, and its strickly limited in performance.
A CCS loaded 12B4 with a step up xformer infront sounds very promising.

Shoog
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Old 13th September 2006, 10:46 AM   #64
MIKET is offline MIKET  United States
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Default Another option for a preamp

How about an Ultrapath 6C45?
http://www.geocities.com/dmitrynizh/Ultrapath.htm
This is a definate possiblility, ultra-simple which agrees with SEWA's design goals.
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Old 16th September 2006, 12:38 PM   #65
Tyimo is offline Tyimo  Hungary
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Hi!
Check this out!
This monster pream could drive everything......!

Greets:

Tyimo
Attached Images
File Type: gif 6c33cb-line_amp2.gif (27.7 KB, 915 views)
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Old 16th September 2006, 12:44 PM   #66
MIKET is offline MIKET  United States
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Quote:
Originally posted by Tyimo
Hi!
Check this out!
This monster pream could drive everything......!

Greets:

Tyimo

It may drive everything but with a typical cd player it won't drive SEWA to 7 watts. The gain of this tube is about 2.4 per section, see data sheet http://www.jogis-roehrenbude.de/Russ...20datasheet%22
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Old 16th September 2006, 01:22 PM   #67
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Default If you want to go SRPP this would be a better choice

Look for "A SRPPed 6H30 Line Preamplifier" on this page http://digilander.libero.it/paeng/hi...ubes_part3.htm
This is a higher gain SRPP using a fairly low impeadence tube.
datasheet at: http://www.jacmusic.com/ehx/datasheets/6H30EH.jpg
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Old 16th September 2006, 01:24 PM   #68
Tyimo is offline Tyimo  Hungary
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Quote:
The gain of this tube is about 2.4 per section
Thanks MIKET! It was only a nice dream.......


Quote:
SRPPed 6H30 Line Preamplifier
It is nice!! I like it! Thanks!

Tyimo
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Old 17th September 2006, 04:06 AM   #69
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Default RJM Parallel Triode Line Stage


What you tube people and SEWA owners think of this RJM circuit?

Quote:
Parallel Triode Line Stage.

Primitive ART and a nod of appreciation to Conrad Johnson.

If I needed a line stage, this is the circuitry I'd use.
The parallel tubes lower the noise and output impedance.
With four 6DJ8 triode sections per channel, the output impedance is 850 ohms.
Gain is about 26 dB.
The gain is too much for a line preamp,
but what about the idea, of parallelling fairly cheep triode tubes
to get better drive in the output?

Here is the circuit:
Click the image to open in full size.

And here is the link to RJM project page:
Parallel Triode Line Stage


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Old 17th September 2006, 07:14 AM   #70
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Hi halo,

CJ does seen to get kudos for their paralleled line stage. Benefit -- a 1/4 the output impedance and 4 x the current drive.

The downside is that you get the average of the transfer curves of 4 tubes (just like paralleling any device) which tends to average out the lowest level of information.

So far i for single stage (what i'd like to see) are the totem pole designs or the idea of a 12b4... the last migt not have low enuff output impedance... this leads to thinking 2 stages, gain stage followed by a follower, but that doesn't have the elegance...

dave
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