Hammond tranny in Valve Jr.

[oldguy]

I believe one of the best mods for my ValveJr. head was the Hammond output transformer I used in it to replace the wimpy stock OT (which is the wrong impedance for EL84's, btw). When a larger output transformer that matches the impedance of the EL84 power tube is installed, the notes throughout the sound spectrum tighten up, smooth out, become more well defined, and sound more musical. That's what I hear in mine anyway. I hesitated to spend $40 on a $99 amp, but since I originally bought it to mod, I went for it. IMHO, the price for this mod is cheap for the results.
Some mercury fanatics have spent upwards of $250 for a complete kit of mods, trannies, chokes, etc. and the sound clips are comparable to the Hammond plus about $20 of caps and resistors IMO.
M29 has done the OT swap, and he seems to like it as well.
Anyway, here are links to some pics I took w/ some notes when I did my OT mod.
As always, remember to work safe, make sure voltages are drained, power is disconnected, and don't attempt a mod like this if you're unsure of your ability, and be aware this will void you warranty.
Lastly, no, a 10w OT will not give you a 10w amp. It will safely handle 10w of power, it does not increase the amp's rated wattage. This is probably one of the most asked questions about replacing OT's, I asked it myself when I began this project.

http://www.box.net/shared/be145cuytd

http://www.box.net/shared/lzs31hgexf

http://www.box.net/shared/yxze4s56pa

[Tone2TheBone]

Oooo more oldguy stuff to listen to. I'll check those out later today at home.

[oldguy]

Oooo more oldguy stuff to listen to. I'll check those out later today at home.


Errrmm...no, Tone... links to pics would be something you'd look at.
If I ever get done remodeling the bathroom I'll try and get some soundclips for you though... with single coils... I promise.

[Tone2TheBone]

Oooo more oldguy stuff to listen to. I'll check those out later today at home.


Errrmm...no, Tone... links to pics would be something you'd look at.
If I ever get done remodeling the bathroom I'll try and get some soundclips for you though... with single coils... I promise.

Forgive me my friend I am new to 'boxin' I'm so used to hearing about sound files there it didn't occur to me that there would be pictures there! I'll have a looksee right now.

[SuperSwede]

I am so jealous of you guys who understand how to do stuff like this yourselves!

[oldguy]

I am so jealous of you guys who understand how to do stuff like this yourselves!

It's really not that hard, SS.
You get an account on Boxnet, upload your files to it, and get a public link to share it here.... then wait for Tone to listen to it........

[duhvoodooman***]

It's really not that hard, SS.
You get an account on Boxnet, upload your files to it, and get a public link to share it here.... then wait for Tone to listen to it........

LMAO!

[Justaguyin_nc]

Lastly, no, a 10w OT will not give you a 10w amp. It will safely handle 10w of power, it does not increase the amp's rated wattage. This is probably one of the most asked questions about replacing OT's, I asked it myself when I began this project.

Did you then ask, what does increase it to 10-15 watts?

I have had the Tranny sitting here for weeks now.. just have not found the the time to put it in... but will.. and your pictures are a very big help OldGuy.. much appreciated! Also got a switch for standby mode I want to add to it.. think that will be it for me and the Epi Head.. well.. for now anyways..

[SuperSwede]

It's really not that hard, SS.
You get an account on Boxnet, upload your files to it, and get a public link to share it here.... then wait for Tone to listen to it........

+1 to oldguy

[Tone2TheBone]

LMAO yeah and not only HEAR but see! Great photos OG!

[tunghaichuan***]

Did you then ask, what does increase it to 10-15 watts?

I have had the Tranny sitting here for weeks now.. just have not found the the time to put it in... but will.. and your pictures are a very big help OldGuy.. much appreciated! Also got a switch for standby mode I want to add to it.. think that will be it for me and the Epi Head.. well.. for now anyways..

A little late to this party, but I got an email from someone asking me that question just yesterday.

One way you could make the VJ an 8-10 watt amp is to add another EL84 in parallel with the one already in it. The PT is beefy enough to be able to supply enough current to support the additional tube. You'd have to change the OT to the Hammond 125ESE or another OT capable of handling 80mA of current (or better) through the core. Also, I've heard of some guys adding a 6V6 in parallel with the existing EL84 to take advantage of the two tubes' differing tonal characteristics.

If I were to do this, I would yank out the PCB and replace it with an eyelet/turret board from turretboards.com. This mod requires that a new hole be punched in the chassis to accomodate the extra tube socket. Also requied would be a new 10w cathode bias resistor for the two tubes.

Another way would be to ditch the EL84 altogether use a 6550 or KT88 tube. Again, the PT has enough current capability. You'd still want to use a 125ESE. I figure you could get 12-15 watts using the aforementioned tube. Again, I would use a replacement eyelet/turret board.

Of course the easiest way to get 15 watts is to buy a 15 watt amp

tung