Eric Tremolux

[tubeswell]

Hi,
Is this the same Animal.
John

Yes. Thanks for that.

[Colossal]

Yep - it starts to break up earlyish (like around '5'), and with over biased little 6V6GTs running flat out with less than optimum bias voltage, the grid current from the output tubes tends to get to blocking distortion quite easily. The 1k5 grid stoppers don't do anything.

With JJ6V6S, it at least biases up properly. The plates are sitting at ~410V@26.1mA (10.6W), which is okay for a 14W tube, and the customer is very happy with the sound. (Whereas previously, the old 6V6GTs running hot were making funny sub-harmonic distortion noises as it got louder)

I daresay you could get away with a 20W rating for the attenuator resistors, because when in use, they are hooked up in combination with the speaker'n'all. The 16R sees half the power of the secondary load, the 8R and the speaker together see the other half the power. Half of 12W is 6W, etc.

Thanks for that summary. The Deluxes all break up early. It's just the bloated flatulence that I can't do. I usually mod them pretty heavily if the player uses humbuckers. But I was quite surprised and pleased with the demo I saw, especially with that Tele. The G1265 seemed to be a great match for that amp.

[tubeswell]

Yes I thought the G1265 went okay with that amp too.

[shane]

Don't suppose anyone has the schematic for the EC twinolux?

[pdf64]

Fender tech support have been quite happy to email me any schematic that I've requested.
I can forward to Twinolux to you; I'd rather not upload it here as I promised not to make it public.

[tubeswell]

FWIW I had an interesting discussion over at ampage and have updated my schematic (in the original post)

Edit 'Dave H' did a sim of the bias supply if one of the .1uF caps is changed to .2 (increases the bias supply to -50V) png attached

Also FWIW - here is a data sheet for the BYD33V (the rectifier protection diodes in this amp). Handy diodes these

[shane]

Thanks for the offer on the twinolux schematic pdf64. I've pm'd you mate
Cheers
Shane

[John G]

Hi,
Not a good copy, but you can see that's going on.
John

[tictac]

Thanks for that.... interesting to see a new Fender amp with a choke input, haven't seen that in a long time....

The tone controls are slightly different from stock too, almost a James tonestack....

TT

[brewdude]

Looks more like an"pi-filter" due to the 22uF Cap before the choke.
Furthermore, voltages would be far lower if it were a true choke input power supply.

[tubeswell]

Thanks for that.... interesting to see a new Fender amp with a choke input, haven't seen that in a long time....

The tone controls are slightly different from stock too, almost a James tonestack....

TT

The twinolux (C-L-C) filter has a capacitor input (C19 in the schematic). A choke input filter would have no capacitor between the rectifier and the choke.

[tictac]

My terminology may be slightly off but my point was the choke is feeding the entire poweramp and preamp including the plates. In the vast majority of guitar amps you don't see this...

I've seen lots of Hifi amp schematics with chokes "after the rectifier and before the plates" both with and without a cap between the rectifier and the input side of the choke and they still are doing the same job of feeding the entire power supply so I always thought they were both choke input supplies...

I've always understood a "PI Filter" to be: cap1 > choke > cap2 with cap 1 feeding the plates and cap2 feeding the screens but I guess cap2 could feed the plates too... (guitar amp centric)

So maybe the correct terminology would be a: "choke input PI filter"?



TT

[Phil_S]

I'd call it a CLC filter. I think the pi filter is done with a resistor?

[TUBEDUDE]

C1 makes all the difference. Without it, it's a true choke input supply. You'll be suprised at how different the output voltage is. A radical drop in voltage!

[Phil_S]

Oh, I know. Thread about choke input here: https://tubeamparchive.com/viewtopic.php?t=28802 Sorry, it's long as i was figuring it out. There is quite a bit of information, both modeled in PSU and empirical.