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The Hundred-Buck Amp Challenge
The Hundred-Buck Amp Challenge
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Old 8th July 2011, 06:38 PM   #501
Wavebourn is offline Wavebourn  United States
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The Hundred-Buck Amp Challenge
Here is corrected schematic, how it is now.
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Old 8th July 2011, 11:32 PM   #502
Printer2 is offline Printer2  Canada
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Originally Posted by PB2 View Post
Is the first .022uF off the first plate there to allow you to use lower voltage caps in the tone stack? It is not needed if all the caps meet the voltage spec, otherwise yes one HV cap there with say a 1 Meg bleed to gound would allow lower voltage caps in the tone stack. Also, the .022uF is in effect in series with the .1 uF and .47 uF in the tone stack at mid and low frequencies and it will dominate the reactance being of much smaller value. Fender often used .022 or .047 uF in the tone stack, did you really intend to use those big values?
Oops it was late, was not paying attention to the numbers too much, you are right about the tone stack. The first 0.022uF I had in place in another design which could switch the tone stack before and after the first triode. I left it in as it allows the option to do it with this board. I never considered the 1Meg though.
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Old 9th July 2011, 12:28 AM   #503
wdcw is offline wdcw  Australia
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Thanks for the replies,

Yeah I see what you mean about the tube circuits & how they have more than likely been built before.

I also am using new transformers for the PS & OPT, I have my circuit almost complete & will test it out later today, it's looking not to bad at the moment with a lot of even harmonic content.

I'm attemting to stay clear of high amplitude odd harmonics as I really don't like ear piercing shrill sounding amps.

Can't wait to try it out.

Cheers
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Old 9th July 2011, 03:51 AM   #504
djgibson51 is offline djgibson51  New Zealand
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Default 1st attempt

6AK5, 6CL6, 38volt tfmr thro flash cap voltage sextupler, wine box (empty now), output tfmr (7500:8) blew the budget. Will have to try the fender 6G15source (thanks Chris A).

Sounds:
Volume - clean from 8 o'clock to 12 o'clock.
grid current clipping from 12 to 3 o'clock
grid current and cut off limiting from 3 -4 o'clock

Tone - good enough not to bother with tone stack
Loudness - bedroom level if nobody else at home

Now for 2nd attempt.
Cheers
JimG
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Old 9th July 2011, 05:00 AM   #505
Wavebourn is offline Wavebourn  United States
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Cool name, "Taste of Gippsland" Click the image to open in full size.
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Old 9th July 2011, 05:37 AM   #506
TheGimp is offline TheGimp  United States
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I'm back to fighting oscillations again.

It looks like it might be feeding back through the power supply.

Last edited by TheGimp; 9th July 2011 at 05:58 AM.
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Old 9th July 2011, 07:13 AM   #507
Wavebourn is offline Wavebourn  United States
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Originally Posted by TheGimp View Post
I'm back to fighting oscillations again.

It looks like it might be feeding back through the power supply.
If you wired ground as drawn on your picture it have to oscillate.
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Old 9th July 2011, 12:32 PM   #508
Cassiel is offline Cassiel  Libya
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Quote:
Tone - good enough not to bother with tone stack
Best tone control. Cool chassis too.
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Old 9th July 2011, 01:37 PM   #509
Printer2 is offline Printer2  Canada
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Hope you celebrated with a glass afterward.
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Old 9th July 2011, 06:58 PM   #510
costis_n is offline costis_n  Greece
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Quote:
Originally Posted by Wavebourn View Post
Here is corrected schematic, how it is now.
Can you please explain the power supply and output stage, it it too strange looking for my feeble mind... Pretty please?
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