Any interest in seeing some Dumble Tweed Deluxe photos?

[Charlie Wilson]

The funny thing is apparently Alexander(or someone) spent hours cleaning and touching up the tweed on this thing. The inside of the chassis was meticulously cleaned also. I was asked about the transformers. Both are the originals. I guess some of the big wig guys have gotten these tweed amps and they are all different depending on application.

[tictac]

Looks like a 33K metal film on the plate of the split load PI. So that along with the adjustable cathode in the 30K-ish range; could Alex be using a 12AT7 in the P.I. ?

TT

[talbany]

Hello Tony, the 10k trim pot is a voltage divider on the cathode of the phase invertor. One end goes to the 4.7k resistor that goes to the cathode of the tube at the junction of the 1meg grid resistor. The other end has the 33k and 56k in series to ground. The wiper feeds the signal to the .1 cap. All it does is move the signal up and down the cathode to balance the phase invertor. The large power tube cathode resistors are two 100 ohms and one 50 ohm. Nothing new there. The 3.3m in series with the .002 cap is a negative feedback loop on the plate side of the phase invertor. Probably to control oscillation and maybe roll some high end off. Voltages on power tube plates about 390v. I am letting the cat out of the bag a little but I do know were the wires under the board go.

Charlie
Thanks for letting out the cat. The roll off cap threw me a bit..Looked much larger than a .002

Have a Good weekend!

Tony

[Charlie Wilson]

Hello, PI has 110k and 100k. The metal film maybe looks like two orange bands but they are brown. All preamp tubes are 12AX7. Also the trim pot doesn't change the total value of the cathode resistance. It just changes where the signal comes off of it.

[beasleybodyshop]

I wonder how long ago Dumble modded this thing? Does it look recent?

[mhartman]

I wonder how long ago Dumble modded this thing? Does it look recent?

Based on the component selection, I would guess that it isn't too old. Most of the parts that he added to the amp were still available from Mouser/AES within the past couple of years. Look closely at the pots, orange drops and CF resistors, those are all current offerings.

[jelle]

So mr. Dumble gutted a vintage Tweed? I hope that amp was not in pristine condition.

[vibratoking]

Gutting a vintage amp just for the chassis and transformers does seem like a bad idea. Although, the iron is seasoned...maybe.

He is possibly the only guy that I can think of that could do that to a vintage amp and raise it's value.

[mhartman]

Gutting a vintage amp just for the chassis and transformers does seem like a bad idea. Although, the iron is seasoned...maybe.

He is possibly the only guy that I can think of that could do that to a vintage amp and raise it's value.

I would certainly let him tinker with my vintage amps (pristine or not).

[jelle]

Ha! Yes.

[Charlie Wilson]

I offered to gut it for him BEFORE he took it to Alexander but Dumble don't roll that way.

[ToneMerc]

So mr. Dumble gutted a vintage Tweed? I hope that amp was not in pristine condition.

5C3 chassis

TM

[ToneMerc]

I offered to gut it for him BEFORE he took it to Alexander but Dumble don't roll that way.

Revised

TM

[tictac]

Hello, PI has 110k and 100k. The metal film maybe looks like two orange bands but they are brown. All preamp tubes are 12AX7. Also the trim pot doesn't change the total value of the cathode resistance. It just changes where the signal comes off of it.

So if the plate of the PI is 110K then it would make sense that the 33K to ground is in series with the 56k and not in parallel. So if the cathode has the 4.7K then the 10K pot then the 56K/33K you'd have a cathode resistor of around 103K which would make sense with a 12AX7....

TT

[talbany]

So mr. Dumble gutted a vintage Tweed? I hope that amp was not in pristine condition.

He did not gut that amp, take look at the pictures and tell me what 2 two things immediately stick out and were not the even common on the original.

Dude is still slick as ever...LOL!

TM

Well the 1 thing I notice is it's not a tweed Deluxe chassis as these have 4 inputs..It's more like a Vibrolux or something 3 hole..none the less the board stll looks like a modified 5E..What are you seeing?

BTW..The 103k there would give more swing and mo headroom..

Tony