Trainwreck Express New Build Transformer Help!!

[prslespaul]

I have pretty much rebuilt my little Epiphone Jr. and feel i can take on a bigger project. I have decided to take on a Trainwreck build, mostly just for fun not to make it the most expensive thing alive. I have seen so many different variations listed on the site as far as transformers go i am getting kind of confused on what works and what doesnt on this thing haha. Anyways i have a few transformers picked out and was wondering what would be a good pick:

http://cgi.ebay.com/POWER-TRANSFORMER-T ... 2555ba716e


That one is 275-0-275, at 100ma. I am unsure whether the 100ma will work or not if not, i have picked out this one:

http://triodeelectronics.com/potrfor10maj.html

A little bigger and 350-0-350, at 290ma which seems to me a little closer.
Which of the 2 would work, or work better?



And far as output Transformers go, I have picked this one

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... TQ:US:1123


I know its better to buy a nice output Tranny, im sure I will upgrade, I am just doing this for fun as of now. Anyways, ANY help would be so much appriciated, I love this forum.

[JamesHealey]

ideally for a wreck express you want 300 - 0 - 300 with 300mA

and you want about 260 - 0 - 260 w/ 300mA for a liverpool

[Allynmey]

That OT won't do it.

[prslespaul]

So none of the trannys will do it?
Whats wrong with OT?
I'd only be running an 8 ohm load, i could run it at 6.6k. Seems to fit the bill?

[spiralstairs]

the OT has a large effect on sound. An OT might work, but not give the sound expected. Toneslut has transformers made to TW specs, best bet for you

Power transformers won't affect the sound so much, but should be the specs above

[prslespaul]

Thanks for the advice, im not really to worried about sound right now because i have a few amps in the studio that sound good as is, im more into just doing it for the fun of it and i dont really want to spend an arm and leg. I am trying to learn, could someone answer this for me please?


How does the ma effect the current? What i mean what is going to happen if i use a 300-0-300, 300ma... VS a 300-0-300, 50ma

I found a vintage stancor p-6119 and it is 300v but only 50ma. I couldnt find any that were 300ma and i know thats what the tonesluts was based on.

Also why would or wont that OT work? (not worried bout tone so much as money)

Any help is appreciated!

[fzfwyv]

Thanks for the advice, im not really to worried about sound right now because i have a few amps in the studio that sound good as is, im more into just doing it for the fun of it and i dont really want to spend an arm and leg. I am trying to learn, could someone answer this for me please?


How does the ma effect the current? What i mean what is going to happen if i use a 300-0-300, 300ma... VS a 300-0-300, 50ma

I found a vintage stancor p-6119 and it is 300v but only 50ma. I couldnt find any that were 300ma and i know thats what the tonesluts was based on.

Also why would or wont that OT work? (not worried bout tone so much as money)

Any help is appreciated!

Don't take this the wrong way but you can spend just a little more for a proper transformer set and do it right. Building an amp without care about the sound is kind of pointless isn't it? That would be the bigger waste of money, IMO.

-Rich

[funkmeblue]

I built an express style of amp using a hammond 272jx power transformer and a jtm45 output. Sounds great to my ears. I also used 6sl7's and run kt66's in it most of the time. I wasn't going for an exact clone.

[Structo]

Add up the heater currents for each tube and you will see how big of a PT you will need.
The key ingredient is the heater supply current.

Each 12ax7 draws 300ma, each EL34 draws 1.5 amps.

3 x 300ma = 900ma and two EL34 = 3 amps.

So right there you have 3.900 amperes.

So a 3 amp heater supply is not enough.

I think it would be smart to use a PT with a 6 amp heater winding.

[prslespaul]

Yeah your right, I guess i should at least get a good OP tranny. And thank you Structo that is exactly what i was after! So lets say the 6.3v runs at 7 amps, on this tranny, but the 270V only runs at 100ma. What does 100ma effect on the board rather than 300ma. I found this one.

http://cgi.ebay.com/600-VOLT-6-3-PREAMP ... 5acf8f346c

Is there a way i could split the 600V into 300-0-300? Also could i wire the heaters up individually or do they have to always run in series? Or am i just getting sloppy now? Thanks again guys!

[Structo]

Most amps run the heaters in parallel.

The trouble with series is like the old Christmas lights, if one bulb goes out the rest down the line go out.

As for what the tubes draw in current B+ wise you just have to look at the data sheets for the tubes in question.

I really like the Duncan tube data sheet locator software.
It works really well. You just type in the tube number and it gives you all the data plus has links to online data as well.

http://www.duncanamps.com/tdslpe/

[soma_hero]

That PT you just listed is indeed 300-0-300 center tapped.

But still won't cut it. EL34 in push-pull will pull about 100ma apiece so you need at least 200 just for the EL34s plus another 20 or so for the preamp tubes.

And there are 4 x 6.3V taps each at different current so you'd need to string all of them in parallel to get enough current to wire your heaters in parallel. That would be a rough job to wire 4 secondaries in parallel. You'd have to put in a terminal strip somewhere to wire them together.

But not enough HT current, so no go...

A good option if you want cheap is to go torroidal. This antek is all you need, for $35. Beat that.

https://www.antekinc.com/details.php?p=58

[prslespaul]

I am still curious to see if you could run it at 350-0-350? That PT was $60 shipped, and 7A to the heaters.

If that wont work, I think im either just gunna run either a Hammond 272JX and a Hammond 1650G or the Tonesluts Set. They both are going to run about 165 shipped.

How does Hammond pair up against the Tonesluts set? Im going to start ordering either tomarrow or the next day, Ill keep you guys posted when i start the build.

[soma_hero]

just get the ToneSlut set. That will take all the guess work out of it. They're tried and true.

[prslespaul]

Those Anteks look appealing, I might actually go with that. PT dont matter as much as the OT as far as tonal qualitys go right? Is there any cheap alternative to an OT? I still dont see why that ot40pp OT wont work?