Newbie Rocket PT Question

[Turbojunkie]

Hi Everyone!
I have a beloved Rocket build with a Heyboer 250/280 (Model 9144?) Power Trans that has the "vibration" problem that others here have experienced, and I'm going to send it out to them for repair.
I have a 260/300 PT on hand for a future Express build. So my question is, would I risk any damage by temporarily installing this one with the 260v taps in the Rocket while the Heyboer is out? Not concerned about any tone differences as it's not permanent, just want to ask you guys if there is any other changes I would have to make for it to be safe....it's my only amp right now.
Very sorry if this sounds ignorant, I'm pretty green with amp building But I am studying books and the search feature!
Thanks in advance for any advice guys!
Turbojunkie

[selloutrr]

It's fine shouldn't damage anything.

[Turbojunkie]

Thanks Selloutrr! I've learned alot from all your posts here at TAG, really appreciate it

[JoeCon]

Turbo,

Does your amp switch between the two PT voltages, and if so do you hear any difference in them?

Thanks.

[Turbojunkie]

Hi JoeCon,
No, amp was not set up with switch for both 250v/280v options, wired up with just the 250v taps...I haven't gotten around to installing my other one yet, been working crazy hours lately, but am happy to report when I do....I don't expect too much of a change, based on what I've been reading. With such a small change, I'm guessing a touch more headroom and punch....but we'll see!

[Turbojunkie]

To JoeCon again,
I just did some more reading, and being a newbie, I have no idea how one would go about setting up a switch for the different PT taps, and don't plan to myself..... but I did find out that KF didn't recommend going too high on EL84's....here's some quotes:
"I build an EL84 powered amp called the Rocket that has a power transformer with two taps so that I can supply the tubes with either 315v or 370v. If I use the higher setting, I get more volume, more headroom and a tighter bottom, but the amp is less dynamic and gives weaker harmonics. If I use the lower voltage, I get better dynamics but a looser bottom."
And another...
"Amps that use EL84's normally run at lower plate voltages than other amps.....Many companies run EL84's at around 400v. That's too much voltage and destroys their tone, in my book. I guess some companies value maximum power and tightness over maximum tone, but it is a matter of taste. Mike, of Dr. Z amps, dropped the plate voltage of his prototype EL84 amp from 400v down to vintage Vox/Trainwreck levels. He then brought his amp down to the local music store and smoked every other EL84 amp on the floor."

I know that Vox PT's were 280v, so personally I don't think I'd enjoy any higher than that, but like he said, it's a matter of personal preference.
Hope this helps in some way.....(and I hope it's OK to quote stuff here on a post )
Take Care,
Turbojunkie

[JoeCon]

Turbo

I got a 280 for my Rocket build. It's a 2 EL84 version.
There are plenty of tweaks that you can do to get your sound.
I'm going for a little more headroom and that tighter bottom.
If I don't like it I can increase the dropping resistors to lower the various B+ nodes to be closer to original Rocket values.

[Turbojunkie]

Oh, OK! So, you can use the higher taps and then adjust dropping resistors to bring it down to where you like! I've got SOOO much to learn....Thanks Joe!
Do you do much gigging in Manchester? I live in So. Maine, but have been commuting to work there, on Dow St. Any good open mics around?

[JoeCon]

Funny I travel south each day to Newton Mass for work.

The Wild Rover does it on Thursday nite and The Shaskeen also has one.

I gig with my old 60's band once in awhile around town. But not too much anymore, giving me time to work on this amp building thing.

[rawnster]

Hey turbo, I hope it turns out ok for you with that mod. Should just rip out that Heyboer and replace it with a MM, or at least a Pacific Tranny from Allyn here on the forum. I believe he's got them in stock right now. Let me know and I can get you a MM for a much discounted price.

[Turbojunkie]

Hi Rawnster!
Been meaning to toss you an email and say "Hi", hope all is well! That is beyond nice of you to offer, as always you're a top-shelf guy!
The amp continues to blow people away...right now it's housed in an ugly old Sovtek Mig 60 head cab with the nameplate removed, and blue painter's tape marking the controls....everyone's says, "huh, what is that?" Then they hear it, corner me and say "Alright dude, what IS UP WITH THAT AMP????" It's hilarious, I've always loved sleeper cars, same kind of thing with this.
Thank you for everything my friend!
Turbojunkie