AC30 and Rocket clips

[Clyde]

Totally unscientific and probably not healthy either, but my buddy recorded 2 clips as identically as he could through his AC30 which I built for him a few years ago and a Rocket which I just finished a few weeks ago. The circuits are identical and both have the cathode cap on the second gain stage. The power transformers are the same, both MM's and the OPT is MM in the AC30 and Toneslut in the Rocket, identical output tubes (JJ) and speaker-a Weber Blue Dog. Preamp tubes....., well no one's perfect. We never even checked.
One amp is red, the other green. They're different but can you tell? We thought one sounded better in the room and the other recorded better-much closer than either of us expected. Have fun.

[rawnster]

Ok, I'll bite. They sound very close. The green track sounds a little warmer and more articulate. So I think.......

Green = Rocket
Red = AC30

[M Fowler]

Red was clean and smooth like a Rocket

Green was more low end gain more squashed drive like an octal tube preamp 6SC7/6SL7 type.

Mark

[CapnCrunch]

Hey Clyde,

what type of files are these? I've never had an issue downloading clips here before, but these come up as a gibberish sort of text.

I don't know what the two clips sound like, but they look pretty the same (Like a drunk Russian sat down and tried to write War and Peace from memory).

[Clyde]

Faint heart never wins fair maiden, and you're absolutely right Rawnster. I wasn't trying to set people up or make anyone look stupid, I just thought it would be fun to see who had their "ears on". We both liked the sound of the Rocket recorded and the AC30 in the room. But.... they were very, very close, as they should be. Essentially what you're hearing is are the differences in the power supply. I'm not sure Capn why you can't get the clips, they're mp3's or m4a's I think.

[M Fowler]

Which power supply was used in that Rocket? I used Edcor 245-0-245 with Dynaco A470-S OT and has a very smooth non breakup sound.

Mark

[Clyde]

Hi Mark,
Both amps have the same MM AC30 Woden power transformer, not correct for the Rocket as voltages are a little high, OPT is MM in the AC30 and Toneslut in the Rocket. Power supply is KF's in the Rocket, vintage in the AC30 (not a whole lot of filtering!).

[Zippy]

Hi Mark,
Both amps have the same MM AC30 Woden power transformer, not correct for the Rocket as voltages are a little high, OPT is MM in the AC30 and Toneslut in the Rocket. Power supply is KF's in the Rocket, vintage in the AC30 (not a whole lot of filtering!).

That's a considerable difference in voltages - you're basically running Liverpool voltages. See the comparo in Gary Hult's thread regarding voltages.

Did you adjust the dropping string to bring the preamp voltages in line with Rocket parameters?

[Clyde]

Zippy, I didn't make any attempt to adjust voltages.

[Zippy]

That should make an audible difference - the Liverpool V1 is ~50V higher than the Rocket V1.

[M Fowler]

I really think the Rocket would better with 300-0-300 tranny.

Mine sounds fantastic but it sure would be nice to have more volume on tap. Thinking that I should be able to get about 45 watts with the EL84's if I build another amp using 280 or 300v tranny.

Mark

[Clyde]

Mark, the MM I used is 285-0-285. I also have a Mojo here that is 280-0-280.

[Lousyatit]

For what it's worth I preferred the Rocket clip.

[mcrracer]

What software do I need to play these clips? They wont play presently.

[rawnster]

What software do I need to play these clips? They wont play presently.

They are .m4a files. iTunes will play them.