Egnater Tweaker 15 PT

[dorrisant]

Looking for advice from some of you who may have had one go bad... Anyone find a good replacement?

MM is $185.

I don't know what no-load voltage to go with or any if the original tx's specs for that matter.

Thinking of getting a set of Edcors... I would like to run EL34s and try some KT66s too. Maybe change the OT primary if upgrading.

Is this circuit worth the trouble?

Tony

[Stevem]

Well el34s and kt66s would need quite a different OT than 6v6s, with the 34s being the most off. The 66s are only some 3k on average off impedance wise.
More than that though both of those tubes can do some 50% more wattage then the V6s so you will never drive them hard enough to get the cream and grit they have to offer when beat on!
The JJ electronics 6v6s are a bit of a cross between a V6 and a 6L6,and sound good,, plus will last a good long time pumping out only 15 watts rms!

[ToneMerc]

Looking for advice from some of you who may have had one go bad... Anyone find a good replacement?

MM is $185.

I don't know what no-load voltage to go with or any if the original tx's specs for that matter.

Thinking of getting a set of Edcors... I would like to run EL34s and try some KT66s too. Maybe change the OT primary if upgrading.

Is this circuit worth the trouble?

Tony

Why don't you ask the man himself, he's a member here at TAG. He posted in the Dumble section today.

TM

[dorrisant]

Why don't you ask the man himself, he's a member here at TAG. He posted in the Dumble section today.

I was figuring that someone, maybe even Bruce, would have one or have worked on one and would know. I borrowed one from a friend of mine and will probably get a chance to open it up tomorrow.

As far as the use of different power tube types, (EL34, E34L, 6L6, 6V6, KT66, EL84 with an adapter, 5881, 6550 and KT77)... I read on another forum that Bruce himself said that these tubes had been tested...

http://www.seymourduncan.com/forum/show ... Tweaker-15

My thinking is that for the cost of the replacement MM PT you could get a set of Edcors, PT and OT. The OT could have at least two different primaries and could be switched to the impedance that will get better results than the stock OT. Some of these power tubes will still not have an impedance selection that is as close as we would like, but it might be a lot closer than what is available stock. What I'm going for is a small bench amp that could be used to test power tubes and 12AX7s.

I think I will PM Bruce... See if he might have done suggestions.

I will go ahead and post those voltages here later for a reference.

Tony

[Leo_Gnardo]

What I'm going for is a small bench amp that could be used to test power tubes and 12AX7s.

Why din'cha say so? In the Leo Lab I have an old Heath W-4M I use for exactly that. Came with a smoked PT, so I found a junker to replace it. I rebuilt the power surprise, and left the output section self-bias (but have plans to alter that to fixed bias.) There are built in jacks intended as insert points for milliammeters so I built a panel with a pair of 100 mA meters & they're left plugged in. Tested thousands of tubes over the last 15 years. Of course it's best to first run 'em thru a regular tester to eliminate shorted tubes. For the usual run of 6L6, EL34, 6550 I use a 5V4 rectifier. When 6V6 are under test I plug in a 5Y3 rectifier. Amp has an octal socket on the side meant to supply power to a preamp, so I built one into a discard reverb tank box for testing the standard 12AX7's & other pin-compatible tubes. To test gain, I run 100 mV sine wave in and measure what comes out. The pre is just a standard Fender-like affair with switchable plate load R's, input pads, output select switch - select meter or monitor audio thru the Heath. Meters won't tell you, but your ears will when it comes to noisy & microphonic pre tubes.

If you're going to build from scratch, I'm sure the Edcor iron would be perfectly good and an immense savings over anything MM. If you can install a multiposition switch for selecting bias voltage, could even run some rough curves on your power tubes. Dual level HV secondaries? A couple of SS rectifiers and a switch so you have nominal hi & lo HV levels for "regular" outputs or 6V6/EL84. Sounds like an excellent project!

[bruce egnater]

Are the transformers bad?

[dorrisant]

Are the transformers bad?

Bruce, thanks for reading... Btw, the friend I borrowed from is Boscoe France.
I'm pretty sure the PT is bad... I disconnected the secondary taps at the pcb and it still blew a fuse. It took a second or two to blow. I measured 27ohms on the primary side and 93ohms on the secondary side. I'm guessing the OT is fine but I didn't check it.

Leo... I wasn't thinking of dual secondaries on the PT but now that you mention it... I'm on the same page though.

I have several tube testers, the main one being a Western Electric cardmatic... but no audio tests on those. I need a solid amp on the bench to test pedals and pickups/guitar wiring anyway, this will certainly fill the void.

Now, where can I source some of those micro toggle switches?

The insanity continues!

Tony

[Leo_Gnardo]

Now, where can I source some of those micro toggle switches?

Alco mini toggles of allsorts at Mouser. Good ones ain't cheap. Also why not ask ApexJr, I'll bet he has barrels of 'em.

[dorrisant]

Ok.. Here's what I got:
.