What is this??

sled108 · 19th July 2008, 04:40 AM

I want to build a Darling 12SL7 Amp... But first I'd like to know what it will be up against..Can Anyone tell me what this is....ST70 W/ JJ KT77 & RCA 6U10'S...What is this??.....

sled108 · 19th July 2008, 04:43 AM

Here's the insides of it...

sled108 · 19th July 2008, 06:37 AM

Here it is in Action...

HollowState · 19th July 2008, 03:14 PM

Nice album cover and 7T. Btw, I'm in Caldwell.

Victor

rdf · 19th July 2008, 04:03 PM

Quote:

Originally posted by sled108
What is this??.....

Almost certainly push-pull. The Darling is single ended. Can't get there from here.

analog_sa · 19th July 2008, 04:19 PM

Quote:

Originally posted by sled108
What is this??.....

A redone Dynaco in a pawn shop?

TubeHead Johnny · 19th July 2008, 05:01 PM

Definitely a heavily modded ST70. The driver board was replaced with a Radio Shack type breadboard. Wiring looks very sloppy. Looks like PT filament wires were cut and a small (not big enough) filament trannie was added on top. Electrolytic capacitors were added and it appears that the original caps are still in the circuit...not a good idea! The choke on the bottom (if it IS a choke) appears to be disconnected as well. Whoever did this should be taken out and shot because he obviously didn't know he was doing! Have it put back in original shape using after market parts.....the iron used in these old Dynos are second to none. It would be a shame to try to mod it into something else.

Shoog · 20th July 2008, 09:39 AM

Doesn't look that bad a job to me (certainly as tidy as most of my jobs). All the right things have been done in terms of added bypassing and beefing up the supply filtering. Granted the original caps should have been replaced, but despite what most people say - those old caps "can" just keep going and going.
If that is a choke then it aught to be put back into circuit. All lose leads from the trannys should be sealed off to eliminate the possability of a case short and overloading the tranny.
As to the driver board upgrade - its probably anm improvement on the original - but its hard to say without tracing the circuit.

Shoog

TubeHead Johnny · 20th July 2008, 07:35 PM

Quote:

Granted the original caps should have been replaced, but despite what most people say - those old caps "can" just keep going and going.

The unpredictability of old caps is well documented. There is no B+ fuse on these old amps...... I've seen many burned out power trannies and smoked rectifier tubes because of this.

jackinnj · 20th July 2008, 09:49 PM

Quote:

Originally posted by HollowState
Btw, I'm in Caldwell.

Victor

I'm in 07078

19th July 2008, 03:14 PM	#4
HollowState diyAudio Member Join Date: Aug 2006 Location: Taxland, New Jersey	Nice album cover and 7T. Btw, I'm in Caldwell. Victor __________________ "The supercomputer is technologically impossible. It would take all of the water that flows over Niagara Falls to cool the heat generated by the number of vacuum tubes required." ~ Professor of Electrical Engineering, New York University

19th July 2008, 05:01 PM	#7
TubeHead Johnny diyAudio Member Join Date: Jan 2005 Location: The Electric City, Schenectady, NY.	Definitely a heavily modded ST70. The driver board was replaced with a Radio Shack type breadboard. Wiring looks very sloppy. Looks like PT filament wires were cut and a small (not big enough) filament trannie was added on top. Electrolytic capacitors were added and it appears that the original caps are still in the circuit...not a good idea! The choke on the bottom (if it IS a choke) appears to be disconnected as well. Whoever did this should be taken out and shot because he obviously didn't know he was doing! Have it put back in original shape using after market parts.....the iron used in these old Dynos are second to none. It would be a shame to try to mod it into something else. __________________ "No man really becomes a fool until he stops asking questions" - Charles Proteus Steinmetz

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20th July 2008, 09:39 AM	#8
Shoog diyAudio Member Join Date: Aug 2002 Location: Eire	Doesn't look that bad a job to me (certainly as tidy as most of my jobs). All the right things have been done in terms of added bypassing and beefing up the supply filtering. Granted the original caps should have been replaced, but despite what most people say - those old caps "can" just keep going and going. If that is a choke then it aught to be put back into circuit. All lose leads from the trannys should be sealed off to eliminate the possability of a case short and overloading the tranny. As to the driver board upgrade - its probably anm improvement on the original - but its hard to say without tracing the circuit. Shoog

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