Twin Rockets

[LeftyStrat]

But not identical twins.

I'v been out of amp building for a while, but I'm starting a build of two Rockets. One for me and one for a friend. My friend wants his in a head shell, but I plan on putting my build in one of rj's hardwood 1x12 combo cabs(http://rjguitars.net/Amp_Cabinets.html). Both will be flipped layouts.

Hope someone can give me a sanity check. I'm planning both tremolo (Jackie Treehorn's schem) and reverb. I'm actually doing two different reverb circuits to check out the differences. One is based on the Ampeg reverb. The other is inspired by this article:

http://www.channelroadamps.com/articles/reverb_driver/

Both are transformer-less.

Some time ago I acquired a huge bag of surplus 1 Meg A pots with a push pull DTDP switch in them.

I plan on the treble push pull switching between standard values and 500pf for the treble cap and a value that escapes me now for the mid cap.

The bass pot push pull will switch the cathode bypass cap between standard and 0.68uf (or to taste).

For OT iron, I have two original cloth lead Dynaco a-470's. For PT I have one of the Toneslut PTs 300/260. I'll probably pick up a Classic Tone that has the same specs.

First question. Has anyone put the two taps on a switch? Isn't this what the Z Wreck does with the speed/comfort switch? I'm concerned about putting those high voltages on a switch. What about the cathode resistor, bump it to 120?

I'd also like to have a LarMar master volume. Which brings me to my second question. Am I going to run into problems combining the LarMar with a bias wiggle tremolo? I'd just replace the ground connection with the bias wiggle circuit, correct?

I've accumulated a bunch of caps to try out in this circuit, polystyrene, PIO, NOS Mustard. The ones I don't have are 6PS, which I assume is what Ken used in this circuit.

I also was planning on using amplates.com for the faceplates. Has anyone tried to do clear with backlighting?

[overtone]

By two taps do you mean two HV taps?

I have done that on a 6V6 SE cathode bias with the HV choice of 195V or 275V on a high quality APEM switch. The cathode bias resistance was two Rk resistors in series. One pole of the switch was wired to short out one Rk to adjust the bias accordingly.

tony

p.s. I never hot-switched that, always decided before powering up. I don't like using switches when playing anyway!

[LeftyStrat]

By two taps do you mean two HV taps?

I have done that on a 6V6 SE cathode bias with the HV choice of 195V or 275V on a high quality APEM switch. The cathode bias resistance was two Rk resistors in series. One pole of the switch was wired to short out one Rk to adjust the bias accordingly.

tony

p.s. I never hot-switched that, always decided before powering up. I don't like using switches when playing anyway!

Thanks. Yeah, I'd like to switch between the two HV taps. That was my concern, someone hot-switching it.

[overtone]

Well I was curious how much of a "pop" hot-switching would create and just tried it out. There is a thump and click which is louder than the signal. I have mislaid my dB meter so cannot say by how much, but loud enough to give you grief at stage volume.

Soundwise, even with that delta of 80V between the two taps, the sound difference is not really dramatic. I have set it up so that the lower voltage gives hotter bias, maybe better response there. But switching DC is something I really like to steer clear of. There is the risk over time of the contacts arcing.

I would advise trying it out temporarily and evaluate for yourself before drilling the extra hole. One switch less is less trouble down the line, especially if the amp is going out the door.

tony

[M Fowler]

I've built four amps with HT switching and have done hot switching without any problems that I am aware of; however, I do not see any reason to continue building amps with the feature. I always seemed to enjoy the higher voltage setting.

Also, I haven't continued the practise of adding 18w/36w switching or diode/tube rectifier switching. Less is best just my opinion having tried all these switching options in amps.

Mark

[LeftyStrat]

I've built four amps with HT switching and have done hot switching without any problems that I am aware of; however, I do not see any reason to continue building amps with the feature. I always seemed to enjoy the higher voltage setting.

Also, I haven't continued the practise of adding 18w/36w switching or diode/tube rectifier switching. Less is best just my opinion having tried all these switching options in amps.

Mark

Thanks Mark. I agree that less is best. I'll not bother with that feature. What about the tone cap switching, do you find that useful?

[LeftyStrat]

Face plates came in today. For these I used Kinko's matte decal with adhesive backing ($17 each).

Sorry for the crappy cell phone pics.