Tweed deluxe half power options

[Reeltarded]

A switch with a pair of 220ks para over output grid leaks. That is about $12 tops and 20 minutes if the iron is cold.

[A.M.]

Layout is fine. You may want to see if you even like this circuit before drilling a hole to mount the switch.

Sure, I might use the ground switch hole on the chassis (since I don't plan to use a standby switch).
As far as the 4 resistors on the switch are concerned, what rating should I use? Is 1 watt sufficent? Carbon comp are ok?

[A.M.]

See if you can find an Eminence "Maverick" speaker. As you twist the magnet structure on the back, (I know this seems weird) you can dial in about 8.5dB of attenuation.

Link to info: https://www.sweetwater.com/store/detail ... hm/reviews

Yes, I saw a video on YouTube and the dial on the back is a very cool feature, unfortunately those speakers are not in production anymore, and not easy to find at all, at least here in Italy...

[sluckey]

1/2W CC is fine

[A.M.]

A switch with a pair of 220ks para over output grid leaks. That is about $12 tops and 20 minutes if the iron is cold.

That sounds like a cool mod to do but I'm not sure how to implement it. Should I install a switch to essentialy bypass the two 220k grid leak resistors?

Thanks!

[Reeltarded]

No! A switch and two other 220ks over the existing pair. It's a PPIMV switch. I am pretty sure a couple people on youtube claiming they have a "patented power cut switch" are just completely full of shit. "Game changers" and "you aren't going to believe what happened" after "I did this thing" types.

The 220ks paralleled over the existing ones drop your grid leaks to 110k. Look at the PPIMV setup and imagine if it was a fixed limit on a switch.

[pdf64]

… The 220ks paralleled over the existing ones drop your grid leaks to 110k...

I can’t envisage it making a ha’penny worth of difference

[Reeltarded]

Makes your amp quieter.. like a PPIMV.

[pdf64]

I can’t see how it will make the amp quieter.
It might wipe a dB or 2 off an LTP’s output, but a 5E3 uses a cathodyne, whose gain will be 1 nearasdammit whether the grid leaks it feeds are 220k or 110k.

[A.M.]

No! A switch and two other 220ks over the existing pair. It's a PPIMV switch. I am pretty sure a couple people on youtube claiming they have a "patented power cut switch" are just completely full of shit. "Game changers" and "you aren't going to believe what happened" after "I did this thing" types.

The 220ks paralleled over the existing ones drop your grid leaks to 110k. Look at the PPIMV setup and imagine if it was a fixed limit on a switch.

Thanks for the explanation! I think I'll try this mod on my tweed Bassman first (which is ready, unlike the deluxe that I'm still building).

[A.M.]

I was searching for ohmite "brown devil" cathode resistors for the Deluxe, and I find either used ones or some new production ones that look like the old model, but are available in only certain values (250, 400, 470...). Then I found these Ohmite audio gold wirewound resistors, do you have any experience with those? Would they sound good in a guitar amp application used as a cathode resistor?

[sterling59]

Have a look at Trinity Amps VRM....https://www.trinityamps.com/product/vol ... odule-vrm/

I built one of their Tweed Deluxe kis and installed this. Simple installation and works well....

[A.M.]

And I’ve finally finished the assembly!



It took me way longer than I originally thought, but since this has been my first real amp build I took my time and didn’t rush through it. Overall it was a very interesting learning experience, and I enjoyed the time I spent assembling it. Probably the least fun part was the heaters wires, but even working with the 18 gauge wire wasn’t as bad as I feared (although not particularly fun!)
In the end I built the amp fairly stock and I haven’t done the power reduction mod discussed in the thread yet, but once I’m more familiar with the amp I will definitely try it. 
I followed the Tube Amp Doctor layout and helped myself by using the StewMac amp kit instructions, which I thought were well done and easy to follow.

My first impressions: it’s very quiet, I used cc resistors exclusively (mostly nos Allen Bradley) but the amp is actually quieter than my Fender Bassman reissue. I swapped out the 1st filter cap with a 30uF which I read can actually make a difference in noise.
I also replaced the first two .1uF caps with .022uF for the normal channel and .047uF for the bright channel, and the phase inverter .022uF with .01uF. The only other mod I did to the circuit is the so called “Ampeg” mod, or “Paul C” mod, which I had on a previous 5E3 I used to own.

The amp sounds a bit brighter than I expected: I barely played it for half an hour so far but I didn’t go past 3-4 on the tone pot, especially on the bright channel. Maybe after the break-in period things should settle in and warm up a bit?


Voltage test gave these results:

Mains 232v AC

12ax7 across pin 9 and 4+5 6.32v AC

B+ 353v DC

12ay7 pin 8 2.02v DC
pin 1 112v DC

Voltage drop on the cathode resistor to ground 18,50v DC

Voltage at 2nd filter cap 315v DC

6V6 plate voltage pin 3 350v DC (5Y3GT)
pin 3-8 330v DC

Based on my calculations I have 97% dissipation at idle, which sounds good to me, but compared to the StewMac info all my voltages read about 10% lower, is that an issue?

[pdf64]

When taking voltage measurements, always include the mains voltage. It may be it was running 10% low.

[A.M.]

When taking voltage measurements, always include the mains voltage. It may be it was running 10% low.

Thanks for the tip! I took some measurements now and edited my former post. What do you think of the voltages?

Arrigo