ampex 6793 stereo

pwdiya12 · 14th June 2012, 01:32 AM

hi,

I am about to recap and re-resistor this amp and wondered if anybody had any comments/advice.

One article I read suggested converting the power supply to full rectification from half wave to gain better tube life and have a wider selection of tubes

any input greatly appreciated

peter

Eli Duttman · 14th June 2012, 02:20 AM

A schematic or a link to a schematic would help.

planet10 · 14th June 2012, 02:52 AM

Beefy looking iron

from the tubes poking up, i'd guess PP EL84.

dave

kevinkr · 14th June 2012, 03:09 AM

PP or SE 6973? The 6973 is rare and can be expensive these days so take care of them.

Schematic and/or pix would be helpful.

Internal chassis shots too?

Sure that this thing does not use a full wave voltage doubler which would have been de rigeur in the 6973 era?

rmyauck · 14th June 2012, 08:31 AM

Would these be good? They've got about the best price. NOS probably better, but like you say hard to find so pricey.

6973 Tube Types

Randy

pwdiya12 · 14th June 2012, 05:00 PM

hi

I will post some pictures shortly.

I have attached a schematic that appears to match the actual circuit, and will need to replace the at least the 100Mfd 250V Electro as they are leaking

Regards

peter

planet10 · 14th June 2012, 05:28 PM

I cleaned that schema up, and made it easier to read if anyone wnts me to post it. I have seen one of those, my buddy Scott scored one. Very nice looking piece of vintage kit.

My advice at the time was to convert it to an El Cheapo variant (using EL84) since 7199 is getting very scarce.

dave

pwdiya12 · 14th June 2012, 05:44 PM

Hi dave

thanks, I would appreciate if you would post the cleaned up schematic and aany information about converting to EL84 operation

Regards

Peter

Triodethom · 06:28 PM

Using the russian 6p14p-ev the high voltage one not just 6p14p is a drop in replacement . I do not stand for what they sound like in this amp just that they will not burn up at 385 like the el-84 and its family will. Other than that the 7189 will take the voltage . Second chose is to drop the plate voltage down to about 290 and run any of them . look like very good iron .
think about putting it on a larger chassis that would give room for choke or other voltage control devices.

planet10 · 14th June 2012, 06:50 PM

14th June 2012, 01:32 AM	#1
pwdiya12 diyAudio Member Join Date: Apr 2012 Location: Peninsula San Francisco	ampex 6793 stereo hi, I am about to recap and re-resistor this amp and wondered if anybody had any comments/advice. One article I read suggested converting the power supply to full rectification from half wave to gain better tube life and have a wider selection of tubes any input greatly appreciated peter

14th June 2012, 02:20 AM	#2
Eli Duttman diyAudio Member Join Date: Apr 2004 Location: Plainsboro, NJ	A schematic or a link to a schematic would help. __________________ Eli D.

14th June 2012, 03:09 AM	#4
kevinkr diyAudio Moderator Join Date: Sep 2004 Location: Boston, Massachusetts Blog Entries: 6	PP or SE 6973? The 6973 is rare and can be expensive these days so take care of them. Schematic and/or pix would be helpful. Internal chassis shots too? Sure that this thing does not use a full wave voltage doubler which would have been de rigeur in the 6973 era? __________________ "Extraordinary claims require extraordinary evidence." - Carl Sagan

14th June 2012, 05:28 PM	#7
planet10 frugal-phile(tm) diyAudio Moderator Join Date: Oct 2001 Location: Victoria, BC, NA, Sol III Blog Entries: 5	I cleaned that schema up, and made it easier to read if anyone wnts me to post it. I have seen one of those, my buddy Scott scored one. Very nice looking piece of vintage kit. My advice at the time was to convert it to an El Cheapo variant (using EL84) since 7199 is getting very scarce. dave __________________ community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi p10-hifi forum here at diyA

14th June 2012, 05:44 PM	#8
pwdiya12 diyAudio Member Join Date: Apr 2012 Location: Peninsula San Francisco	schematic and el84 Hi dave thanks, I would appreciate if you would post the cleaned up schematic and aany information about converting to EL84 operation Regards Peter


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14th June 2012, 08:31 AM	#5
rmyauck diyAudio Member Join Date: Apr 2009	Would these be good? They've got about the best price. NOS probably better, but like you say hard to find so pricey. 6973 Tube Types Randy

14th June 2012, 06:25 PM	#9
Triodethom diyAudio Member Join Date: Dec 2009 Location: Newnan GA	Using the russian 6p14p-ev the high voltage one not just 6p14p is a drop in replacement . I do not stand for what they sound like in this amp just that they will not burn up at 385 like the el-84 and its family will. Other than that the 7189 will take the voltage . Second chose is to drop the plate voltage down to about 290 and run any of them . look like very good iron . think about putting it on a larger chassis that would give room for choke or other voltage control devices. Last edited by Triodethom; 14th June 2012 at 06:28 PM.

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