Which would you use in Express build

[andrew]

I have a 40watt 4k Heyboer and a 25 watt 7.7k Hammond. Which would you use with EL-34s in an Express build? Thanks.

[RJ Guitars]

Andrew,

First my disclaimer - Each Trainwreck amp is built with a lot of interaction between the components, so you might find that either or neither give you the Express sound... I am a bit of an experimenter so I would probably proceed knowing that it will be some extra work to dial the amp toward a Trainwreck vibe. I generally believe you can get where you want to if you understand things adequately... Ken Fischer himself had a tendency to use whatever parts he had on hand yet somehow always got the tone he wanted... he was also famous for tireless tweaking until it sounded right to him.

Based purely on the wattage specifications the 40 watt unit is the better choice. A couple EL34's would be working a 25 watt tranny pretty hard.

Give us a report when you get it all together.

rj

[andrew]

Hi, I tried the 7.7k Hammond with EL-34s and it was bright and harsh (6v6s sounded better) Maybe I''ll use the 4k. Then again I might use 6v6s with the lower power taps. Too many choices. I'll try to get it together.

[RJ Guitars]

Andrew,

That 7.7K Hammond would make a pretty sweet transformer for a half power Rocket or Liverpool. Two EL84's would be just about right for that impedance and you sure won't hurt anything having a little over rating for the power output.

The 4K impedance of the bigger transformer is not a bad match to a pair of EL-34's...

rj

[rooster]

I use the Hammond 25 watter with the 7600 ohm primary with 6V6s. I also ran EL34s in it and, like you, I didn't like the sound of things. Well, RJ has set things right here, but remember that the typical primary of the OT that KF used was 6600 ohms. It should also be noted that, whether everybody was happy with the explanation or not, Alan Phillips felt that a higher impedance OT used in an EL34 application, 6600 vs. 4K for example, stiffled the odd order harmonics. ?? Maybe this is the case but I sure don't have a way to test this. But I do think about it, you know?

Any, my overall thinking on the subject of OTs is that there is some magic to be had in an OT, although I would not be the guy to qualify how much. First you need to make sure everything else is up to speed before you would even begin to know it, of course. Also I cannot emphasize the importance of a good speaker or two in the chain. My experience says a good speaker can more easily counter a marginal OT - where a great OT is still going to sound like crap into a crappy speaker...

[andrew]

I have two Rockets with the same pre-power amp components. Number 1 has Moose's 260vPT with a Triode DYNACO 4.2k, 158L and 4 Saratovs. Number 2 has a 270vHammond PT,Hammond 7.6k 25watt OT, 156L, and two JJs. I used the same preamp tubes and to my surprise I like the Hammond setup a little better. With my guitar volume about half way #2 gets a nice acoustic smooth sound and feel while #1 stays tighter and less airy. I did notice #2 has a 40uf in the PI node and #1 has a 20uf. Also #2 has a 100ohm/100uf.( I think most use 120-150 ohms) Would it be possible to emulate the sound of #2 or do 4 el84s just have more mids? Any ideas would be helpful!