"2 Stage" PP 7591 Amp - Page 12

dhaen · 22nd December 2005, 04:44 PM

Fortunately the positioning of this particular MOV in this application does not expose it to mains transients. It is merely across a choke.

Quick-start PSU V1.3:

anatech · 22nd December 2005, 10:08 PM

Hi John,
Well, hang one across the primary of the power transforer too! They come in pretty colours.

-Chris

dhaen · 22nd December 2005, 11:47 PM

We don't get mains bumps. Far from industry, local mains distrubution below ground, and relatively few storms compared with other climes. Poor territory for MOV salesmen....

anatech · 23rd December 2005, 03:04 AM

Hi John,
Lucky you! We live in zap central. Lightning and industry.

-Chris

Eli Duttman · 24th December 2005, 10:51 PM

All,

Take a look at the level control at the amp's I/P. If a precision stepped attenuator is used as the grid leak resistor of the inverting triode, the low 10 KOhm I/P impedance inhereted from "El Cheapo" can be eliminated. It makes NO sense to put controls that cost as much as the entire amp into a LOW budget project. This project is more about good sound and less about pinching pennies.

A high precision resistance is needed in order for the filters at the I/Ps of the 2 channels to have an "identical" turn over frequency.

Eli Duttman · 26th December 2005, 03:14 PM

This post is an utterly shameless bump.

Dec. 26 is Boxing Day. Is that for fisticuffs or for packaging?

dhaen · 3rd January 2008, 08:42 PM

Eli,

Just revisiting.....
Can you remind me about the 10% tertiaries please:
Are each 10% of each anode winding?
And... on reflection, does 8K A-A sound in the ballpark? Bearing in mind that the "seen" impedance will be higher due to the cathode feedback.

Thanks,

Eli Duttman · 3rd January 2008, 11:55 PM

John,

IIRC, each CFB winding is 10%. I'm not sure if 8 KOhms, end to end, is enough. Near Class "B" operation pushes the impedance needed up.

Brett · 15th March 2008, 05:05 PM

John, did you ever build this?

22nd December 2005, 11:47 PM	#113
dhaen diyAudio Moderator Emeritus Join Date: Jun 2002 Location: U.K.	Forget the pretty colours.... We don't get mains bumps. Far from industry, local mains distrubution below ground, and relatively few storms compared with other climes. Poor territory for MOV salesmen....

24th December 2005, 10:51 PM	#115
Eli Duttman diyAudio Member Join Date: Apr 2004 Location: Plainsboro, NJ	All, Take a look at the level control at the amp's I/P. If a precision stepped attenuator is used as the grid leak resistor of the inverting triode, the low 10 KOhm I/P impedance inhereted from "El Cheapo" can be eliminated. It makes NO sense to put controls that cost as much as the entire amp into a LOW budget project. This project is more about good sound and less about pinching pennies. A high precision resistance is needed in order for the filters at the I/Ps of the 2 channels to have an "identical" turn over frequency. __________________ Eli D.

26th December 2005, 03:14 PM	#116
Eli Duttman diyAudio Member Join Date: Apr 2004 Location: Plainsboro, NJ	This post is an utterly shameless bump. Dec. 26 is Boxing Day. Is that for fisticuffs or for packaging? __________________ Eli D.

3rd January 2008, 11:55 PM	#118
Eli Duttman diyAudio Member Join Date: Apr 2004 Location: Plainsboro, NJ	John, IIRC, each CFB winding is 10%. I'm not sure if 8 KOhms, end to end, is enough. Near Class "B" operation pushes the impedance needed up. __________________ Eli D.

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22nd December 2005, 10:08 PM	#112
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi John, Well, hang one across the primary of the power transforer too! They come in pretty colours. -Chris

23rd December 2005, 03:04 AM	#114
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi John, Lucky you! We live in zap central. Lightning and industry. -Chris

3rd January 2008, 08:42 PM	#117
dhaen diyAudio Moderator Emeritus Join Date: Jun 2002 Location: U.K.	Eli, Just revisiting..... Can you remind me about the 10% tertiaries please: Are each 10% of each anode winding? And... on reflection, does 8K A-A sound in the ballpark? Bearing in mind that the "seen" impedance will be higher due to the cathode feedback. Thanks,

15th March 2008, 05:05 PM	#119
Brett diyAudio Member Join Date: Jan 2002	John, did you ever build this?

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