Just in case you don't think careful building matters...

[prspastor]

My friend and I both have built Express amps here recently. We've used the same parts for everything.

I approached my amp with extreme care and attention to lead dress.
My friend's amp does not have the lead dress we often talk about here at Amp Garage.

We finally fired my friend's amp up yesterday. I noticed immediately major differences between our amps. (Same tubes, same speaker cab, same guitar, different amps)

1) String to string definition is much better in my amp.
2) My amp is much more three dimensional/swirling in its clean tones.
3) The overdrive characteristics are very different.
4) My amp has a smooth roll up from clean to dirty. His amp is more abrupt.

Lead dress and careful work does matter in these amps. I'm new to building and I was shocked at the differences. What an education...

[ampgeek]

Amen brother! Thanks for sharing those observations.

When you say "same tubes" do you mean that you swapped one set back and forth? If not, that would make for an interesting little additional test.

I have also observed how important power tube biasing is (actual current draw as opposed to straight bias voltage). Making that variable fixed during comparisons is worthwhile in my book.

Thanks again,
Dave O.

[passfan]

Aren't you glad you didn't try to cram it into a smaller chassis ?

[mobisimo]

If it's not too much trouble, Prspastor, would you be able to post some pics of these amps?

The lead dress on my first amp--an 18 watt---was pretty goofy. It had a pretty brown sound and was light on gain. After I cleaned it up it got very bright and gainy. The coupling caps were 715P because Mallory 150s were in backorder at the time. Once I subbed the 150s in it tamed the highs but the overdrive still could have been smoother. That amp too seemed particularly sensitive to lead dress and coupling cap dielectric.

[prspastor]

Amen brother! Thanks for sharing those observations.

When you say "same tubes" do you mean that you swapped one set back and forth? If not, that would make for an interesting little additional test.

I have also observed how important power tube biasing is (actual current draw as opposed to straight bias voltage). Making that variable fixed during comparisons is worthwhile in my book.

Thanks again,
Dave O.

Exactly, we swapped the same tubes from the same valve positions back and forth. V1 to V1, V2 to V2, etc. The EL 34s were biased at 40ma of idle current.

I have found that I like my EL 34s at 65%. That seems to set well for me.

These are interesting observations and add to the research that tells us that every little thing does matter.

I certainly don't want to denigrate my friend's amp and elevate mine, however I thought that the distinctions were too important not to note in the forum.

[prspastor]

If it's not too much trouble, Prspastor, would you be able to post some pics of these amps?

The lead dress on my first amp--an 18 watt---was pretty goofy. It had a pretty brown sound and was light on gain. After I cleaned it up it got very bright and gainy. The coupling caps were 715P because Mallory 150s were in backorder at the time. Once I subbed the 150s in it tamed the highs but the overdrive still could have been smoother. That amp too seemed particularly sensitive to lead dress and coupling cap dielectric.

I'll be happy to do this - just be kind with the critique. I'll attach mine below and I'll ask my friend for a photo or two of his amp and then post them. I used Mallory 150s in this amp, with a Sozo for the presence. I bought a complete set of Sozos for this amp as well, but I'm pretty happy with the Mallory 150s so I'll probably keep them in there. I think they are pretty nice caps. Seem to be pretty smooth.

I've set myself up a small recording studio so I hope to record some tracks and post them in the next day or two.

[img:640:480]http://lh4.googleusercontent.com/-PFPm0 ... M_0180.JPG[/img]

[img:640:480]http://lh3.googleusercontent.com/-zBpkF ... M_0181.JPG[/img]

[img:400:300]http://lh4.googleusercontent.com/-BD9Ml ... M_0182.JPG[/img]

[img:400:300]http://lh4.googleusercontent.com/-TEM4X ... M_0183.JPG[/img]

[img:400:300]http://lh4.googleusercontent.com/-upWPk ... M_0184.JPG[/img]

[img:400:300]http://lh6.googleusercontent.com/-KIB3g ... M_0185.JPG[/img]

[Tyrannocaster]

Nice build, man. I would like to hear it! The only thing I would note is that style of buss bar across the back of the pots makes it a nightmare later on if you have to replace one of them. But I don't have a better solution.

[BarryW]

I always run a floating buss between the board and the pots and run wires down to it. It's held in by the connections to the board and grounds run to a point near the input jacks. Works great, dead quiet on every amp I've used it on.

Nice build, man. I would like to hear it! The only thing I would note is that style of buss bar across the back of the pots makes it a nightmare later on if you have to replace one of them. But I don't have a better solution.