TA,
6GW8s are scarce. If you have NOS in your pile, sell them to partially fund your project.
May I immodestly suggest "El Cheapo". You can get 12 very honest WPC from an EC built with Dynaclone Z565 O/P trafos and operating in ultralinear mode. Triode wired "finals" (as shown) are good for 6 sweet WPC. Any 6V6 family tube works with the parts values shown. Saratov, Russia, made "reissue" TungSol 6V6s have shown themselves to be at least the equal of the remaining NOS.
IMO, it's a good thing when an amp you plan on using for a while employs tubes that are currently being produced.
6GW8s are scarce. If you have NOS in your pile, sell them to partially fund your project.
May I immodestly suggest "El Cheapo". You can get 12 very honest WPC from an EC built with Dynaclone Z565 O/P trafos and operating in ultralinear mode. Triode wired "finals" (as shown) are good for 6 sweet WPC. Any 6V6 family tube works with the parts values shown. Saratov, Russia, made "reissue" TungSol 6V6s have shown themselves to be at least the equal of the remaining NOS.
IMO, it's a good thing when an amp you plan on using for a while employs tubes that are currently being produced.
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I like the El Chepo. I am going to build it. Do you have a parts list by chance? I want to by an assorment of caps for audio dyi projects, what is a good capacitor for audio. The Mullard 6GW8 tube that was is my Newcomb model ED 10C when I bought it is the only one I have. I started playing with it last night and it looks like the filment winding on the p/s transformer is shorted. I do want to play with this one so I am going to start looking for another transformer.
matt
matt
Matt,
Jim McShane will sell you all the parts you need to build an "El Cheapo", except magnetics and casework. Jim's site is here.
If you can find the money, buy Dynaclone Z565 O/P trafos from Triode Electronics. The price/performance ratio of the Z565 is very hard to better.
If something less expensive is necessary, buy Edcor's CXPP25-6-7.6K model. The guitar amp O/P trafo shown in the drawing has (sadly) ceased to be a bargain.
Allied Electronics has a full set of power magnetics. Stock # 967-2343 is the Triad N-77U main B+ trafo. Stock # 227-0034 is the 6K27VF B- and 12AT7 heater trafo. Stock # 967-1004 is a Triad C-24X filter choke. Stock # 967-8019 is a Triad VPS24-1800, whose 2X "12" V. windings take care of O/P tube + 12AL5 heater power and B+ boost.
Oh yeah, the LENGTHY saga of "El Cheapo" is here.
Jim McShane will sell you all the parts you need to build an "El Cheapo", except magnetics and casework. Jim's site is here.
If you can find the money, buy Dynaclone Z565 O/P trafos from Triode Electronics. The price/performance ratio of the Z565 is very hard to better.
If something less expensive is necessary, buy Edcor's CXPP25-6-7.6K model. The guitar amp O/P trafo shown in the drawing has (sadly) ceased to be a bargain.
Allied Electronics has a full set of power magnetics. Stock # 967-2343 is the Triad N-77U main B+ trafo. Stock # 227-0034 is the 6K27VF B- and 12AT7 heater trafo. Stock # 967-1004 is a Triad C-24X filter choke. Stock # 967-8019 is a Triad VPS24-1800, whose 2X "12" V. windings take care of O/P tube + 12AL5 heater power and B+ boost.
Oh yeah, the LENGTHY saga of "El Cheapo" is here.
Buy Russian caps on ebay, teflon for instance. A lot of info can be found on this board.
You can also use soviet 6V6 tubes in the El Cheapo to keep it cheap and still sounding good.
And I suppose you could use the 6n1p tube at the front
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I dug around my parts box, and found an old (cheap) 1960s console stereo amplifier. It has almost the equivalent schematic to your Emerson, using 12AX7 driver and 50EH5 pentodes driven in SE through tiny little cheap transformers for about 1.4 Watts/channel.
Naturally, it doesn't have a transformer. The power cord solders directly onto the circuit board. It's a deathtrap! Zap!
Anyway, I figure I can rebuild this thing for a few dollars:
1. Replace the old film capacitors with ones from Parts Express (i.e. Solen, Jantzen, or Dayton Audio). A few dollars.
2. Google "Type FP" three-section capacitor, and there are several vendors offering a replacement type at reasonable cost ($10-$12).
3. Buy a 1:1 isolation transformer.
Voila! You may want to consider the same strategy instead of a wholesale redesign. The 50EH5 with those tiny SE transformers will retain the 60's sound - for better or worse - and you don't have to worry about reconfiguring the chassis layout for larger tubes, components, and power dissipation - and designing a new circuit.
Naturally, it doesn't have a transformer. The power cord solders directly onto the circuit board. It's a deathtrap! Zap!
Anyway, I figure I can rebuild this thing for a few dollars:
1. Replace the old film capacitors with ones from Parts Express (i.e. Solen, Jantzen, or Dayton Audio). A few dollars.
2. Google "Type FP" three-section capacitor, and there are several vendors offering a replacement type at reasonable cost ($10-$12).
3. Buy a 1:1 isolation transformer.
Voila! You may want to consider the same strategy instead of a wholesale redesign. The 50EH5 with those tiny SE transformers will retain the 60's sound - for better or worse - and you don't have to worry about reconfiguring the chassis layout for larger tubes, components, and power dissipation - and designing a new circuit.
Even better, I've been looking for 120:110 isolation transformers to power old equipment. Power in the 1960s was about 110VAC. Modern utility power is about 122VAC. The 10% higher voltage stresses the filaments, possibly capacitors, and increases plate current. The Hammond 169C looks about perfect for the job, providing line isolation while simultaneously reducing the voltage to 1960's standards. The 169C costs about $50, about the same you'd pay for a power transformer anyway.
Replacement 50EH5 tubes are cheap ($5-10) from a variety of sources. Yours still may have some life. With a SE design, you don't worry as much about asymmetrical aging as PP designs.
Replacement 50EH5 tubes are cheap ($5-10) from a variety of sources. Yours still may have some life. With a SE design, you don't worry as much about asymmetrical aging as PP designs.
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Hi K,
You may find this page interesting:
Audion visits Wu Flingpoo
The schematic link is at the bottom of the page. 1960s console stereo amplifier modded by Joe Rosen.
You may find this page interesting:
Audion visits Wu Flingpoo
The schematic link is at the bottom of the page. 1960s console stereo amplifier modded by Joe Rosen.
No go! There's a big difference between μ=60 (12AT7) and μ=33 (6Н1П). "El Cheapo" is an "integrated" amp. A line stage is not needed for CDP signal sources. Also, the NET harmonic distortion spectrum will be adversely affected, if another type is substituted for the 12AT7.
SY likes JJ's current production 'T7s. Mullard made NOS can be had for about $25.
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