Pyramid-IX monoblock, 200W from 4x GU-50 - diyAudio
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View Poll Results: Which side should be the front?
Long 11 28.21%
Short 28 71.79%
Voters: 39. You may not vote on this poll

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Old 25th November 2012, 10:57 PM   #1
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Default Pyramid-IX monoblock, 200W from 4x GU-50

Hi!

I am building a prototype of the amp, it will be monoblock, 200W output, 4xGU-50.
I have a dilemma, which side should be the face, with front panel?
Usually monoblocks have short face. But if to make the front panel on the long side it will be 19" rack mountable. Which road should I choose?

The front panel will contain only power switch and volume control. Rear panel will contain power socket, fuse, output binding posts, RCA and XLR sockets, RCA-XLR switch.

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Old 25th November 2012, 10:59 PM   #2
Bigun is offline Bigun  Canada
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Wow, this is an interesting amp

With the layout you have chosen, I vote for short face as the front, then when you look at it you see row of shielded tubes and behind a row of monsters!
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Old 25th November 2012, 11:05 PM   #3
Ejam is offline Ejam  Australia
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Default 200W Amp Schematic?

Wavebourn

Any chance of a schematic or a description of your new creation?
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Old 25th November 2012, 11:15 PM   #4
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Quote:
Originally Posted by Bigun View Post
Wow, this is an interesting amp

With the layout you have chosen, I vote for short face as the front, then when you look at it you see row of shielded tubes and behind a row of monsters!
They will not be shielded, I just put sockets to see sizes. One will be cat's green eye.

If to make the face short It would be better to put input sockets on the front panel, but power switch on the rear one.

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Originally Posted by Ejam View Post
Wavebourn

Any chance of a schematic or a description of your new creation?
Sure, no problems. Everything will be in public domain with disclaimer, "800 Volts kills!"

May be I will sell PCBs, if somebody wants.
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Last edited by Wavebourn; 25th November 2012 at 11:20 PM.
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Old 25th November 2012, 11:55 PM   #5
AJT is offline AJT  Philippines
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can you tell part numbers of those Edcor's please......
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Old 26th November 2012, 12:03 AM   #6
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Quote:
Originally Posted by Tony View Post
can you tell part numbers of those Edcor's please......
Special order for power transformer. Output transformer is 4k2 for 100W from 20 Hz. From 40 Hz it will work nice for 200W, but I should try first. CXPP-100-MS-4.2K
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Old 26th November 2012, 12:18 AM   #7
AJT is offline AJT  Philippines
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thanks, i like the beige colored traffos.....
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Old 26th November 2012, 01:40 AM   #8
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So, I am curious. Will this be pentode operation of the ordinary sort, or incorporate some of your Schade magic? I suppose what I am asking is, Can you give some basic circuit description? I have read more than a couple of threads regarding the gu-50. I have noticed that you have put quite a bit of time into developing circuits with this valve and will follow this thread. GU-50...Wavebourn...these two are always found together, it seems.
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Old 26th November 2012, 01:48 AM   #9
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Wavebourn, I have been meaning to ask about the GU-50 sockets. Is it necessary to have all the metal support pieces, or can they be removed to make a more "normal" looking socket? Thanks, gary
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Old 26th November 2012, 01:48 AM   #10
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Yes, it will be in pentode mode, with local feedbacks across output tubes. The difference from previous Pyramids, MOSFET followers to drive output tubes, and 2 tubes in parallel for twice higher power. However, the power will be rated for frequencies from 40 Hz, instead of 20 Hz, but it is plenty, since such amps either drive Magnepans at homes, or concert line arrays. For subs (frequencies below 40 Hz) I believe class D amps are better.

I would not suggest to remove all that "extra metal" from sockets: pins are thin, and key is on the glass, so it is easy to insert tubes wrongly damaging the amp.
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