Building my first express. Good OT for 6V6 use only?

[morcey2]

Hi everyone,
My name is Matt and I've sniffed way too much solder fumage in the last three years. As a result, I've decided to build an Express. I see lots of familiar names here from {18,pp,se,45}watt.com and AX84. A friend of mine wants to try an express and I've wanted to build one for a year or two. I just have a couple of questions:

I have enough trouble cranking my Plexi6V6, so I don't think having EL34's would gain me much in an amp that has lots of power tube distortion. What would be a good OT for 6V6 only operation? I've got a couple of MPS 6k6 OT's, and would be willing to get hammond trannies (maybe 1650F or deluxe reverb replacement) or 18watt OT's if they would fit the bill.

I have several 16x8x2 hammond chassis that I would like to use. (too flimsy for the toneslut trannies. another reason for the 6V6s). Being that the express is very sensitive to layout and lead-dress, what is the best way to make up for that lost inch of width?

I'll probably be using either a hammond 270FX or a MPS PT285V for the power. I've got a 270FX in my 18-watt and B+ is 360V after the sag resistor, so I should be good with either one. (I wish AES sold the 270EX). Any qualms about any of those?

I hate wasted triodes, so how much of a change would it make to parallel the first stage or the third stage? (with the appropriate adjustment to connected components.)

I've looked at all the revisions in the schematic PDF and I'm kind of leaning toward A1a or A4. Any versions I should avoid?

And finally, what is the deal with the 1K/25W resistor in the PS? The most I can see it dissipating is about 2W. Is there a reason it's 25W other that that's what KF used?

So, am I headed in the wrong direction on any of this?

Thanks,
Matt

[jaysg]

I've looked at all the revisions in the schematic PDF and I'm kind of leaning toward A1a or A4. Any versions I should avoid?

All of those. Dig a bit deeper -- you will find actual schematics of the real deal. Search for anything about Francesca, Kelly, and Trudy. I can't really help with the iron questions. I think any 18W set would do, so what do I know?

[GrungeMan]

I've seen Wrecks built on the same Hammond chassis's using Mooses Tranny's, no big deal they work just fine.

Grungy

[gearhead]

I've looked at all the revisions in the schematic PDF and I'm kind of leaning toward A1a or A4. Any versions I should avoid?
Matt

Use Dr. Hulseys; it's been reviewed/refined quite a bit:

https://tubeamparchive.com/viewtopic.php?t=2930&start=0

And finally, what is the deal with the 1K/25W resistor in the PS? The most I can see it dissipating is about 2W. Is there a reason it's 25W other that that's what KF used?
Thanks,
Matt

A pretty common (and valid) question; the most esteemed Mr Ruby replies:

https://tubeamparchive.com/viewtopic.ph ... hlight=25w

BTW, welcome to the gang!

Recommendation; Start diving into the search function; there is a whole lot of info tucked away in various threads. The search function on this site isn't "and" by default ("or" is default). If you are looking for, say, express bias , you actually need to type in "express and bias". Otherwise your search will return all threads with bias and all threads with express.

[dansamp]

I built a wreck type amp in a Traynor Bassmate chassis
I used the original Hammond PT and used a Stancor 3800 OT with a 5K primary it sounds great with 6V6 tubes
Dan...

[RJ Guitars]

The Trainwreck trannies on the Toneslut site should be ideal... They have a 5.2K tap and and a 6.6K tap. The 6.6K is a pretty good match to the 6V6's and the 5.2 works out good for the El34's as far as matching up to the tubes..

The price there is about as good as you'll find and they have a very good track record here at AmpGarage.

Listen to them both and then give us a report... I'd love to hear more info on the 6V6 Express build.

rj

[John_P_WI]

You could easily use the Hammond 1620. Its $15 less too.

John

[Buschman]

Bite the bullet and build it with good trannys that will run anything. El34s just seem to sound sweeter in this amp to me. They are only a bit louder. I utilized a triode switch for a volume reduction when necessary. You will have a badass amp to be proud of.

If you have good 6v6 iron and just want to build something then that would be a different story. The chassis should be fine as there is lots of extra room in the in the original chassis

[Buschman]

Bite the bullet and build it with good trannys that will run anything. El34s just seem to sound sweeter in this amp to me. They are only a bit louder. I utilized a triode switch for a volume reduction when necessary. You will have a badass amp to be proud of.

If you have good 6v6 iron and just want to build something then that would be a different story. The chassis should be fine as there is lots of extra room in the in the original chassis

[jjman]

I’m using the Toneslut trannies on my new Express-inspired amp with the 6.6k tap and 6v6s with cathode biasing. I placed the trannies at the rear corners instead of next to each other which helped reduce the sagging of my cheap chassis. They are heavy trannies. I’m very happy with the tone.

I also questioned the use of a 25watt power resistor and used a 10watt since I had one already. I then switched to a 25watt since I needed to pick up a few more parts near the end of the build anyway. I told myself that maybe it might reduce hiss a tad. The xicon ones are cheap on Mouser.

[morcey2]

Ok, I've come to a conclusion. Since I'm building 2, I'll build the first one as a 6V6 only using what I've already got other than the OT. I'll order a 1620 and use that. For the second one, I'll either go w/ the tonesluts or a 272HX/1650H for the trannies.

I looked at Dr. Hulsey's schem and Dana's francesca schem and realized I had already printed them up last week.

Any thoughts on the parallel triode question?

Matt