Asteroid 60

[Structo]

Are you sure the switch wouldn't go on the 22K?

OK I understand the different plate resistance but why the fast/ gradual designation.
Does it change the attack of the note?

[Rimy]

the plate resistance is the same, otherwise you would change the plate-current.
it's just the way the AC-signal has to go trough. the DC on the plate stays the same.
the sound in the grad position is softer, less gain and less attack.

[M Fowler]

Thanks guys, the cab is mahogany with curly maple V front. Distortions can tell you more about the cab then I can.

The fast/gradual switch goes between V1 pin6 and V2 pin7 for more gain.

Mark

[billyz]

The fast/gradual switch goes between V1 pin6 and V2 pin7 for more gain.

Mark

Assuming 100K as a starting point, it reduces the gain. If you switched between a 100k and a 220K ( for example) then it would increase gain.

When I first monkied around with this circuit I wired it wrong and was actually switching between a 82K plate load and 22K plate load. It works and does reduce the gain as well. But not as much as the fast gradual switch.

[Tonegeek]

Very nice! That looks just like the real deal. Did the trannies come with that hammertone finish or did you do that?

[guitarsnguns04]

where can I get the parts to build one of these? does anyone know? I check my pms often..help me!! lol..thanks

[M Fowler]

Barry (bnwitt) painted and prepared that chassis/tranny covers. He must have felt sorry for me as Barry provided all the parts and dam near built the entire amp before shipping it to me.

I populated the boards and did the wiring. Thanks goes out to Barry and Allyn Meyers because without them this amp could not have been built.

Mark

[bnwitt]

Mark,
I'm glad this build worked out well for you. You did a fine job on it. As far as a footswitch add on for the preamp gain function, I know Allyn has implemented this but I don't have much to share on it. Maybe he will jump in here with some details. If not, It wouldn't be hard to install a footswitch jack that bypasses the toggle switch and allows a switching device to do the work with a foot pedal.

Be aware that as the original switch is wired, it not only has the preamp AC signal from the previous stage present on the terminals, but also the plate voltage. This is really not necessary since the only thing the switch is doing is either sending the full AC signal to the next stage or attenuating it some through the 82k resistor. The switch output then goes to the 0.1uf coupling capacitor which blocks the DC plate voltage from the previous stage and only allows the signal to pass.

I have attached a drawing that shows how to put only the signal on the switch by using two 0.1uf caps prior to the switch and eliminating the one downstream as it becomes obsolete. This was communicated to me from Allyn. The 1 meg resistors shown in the drawing eliminate switch pop. With this mod (and a switching jack) you could then add a switching relay assembly of some kind to implement the foot pedal.

At the moment I am heavily involved in my new solar energy business, but if I find the time in the near future I will attempt to put a drawing together for it. I do think Allyn has the full scenario, however.

Have fun playing that amp, and Larry, the cab looks awesome. For all of you guys looking for a cab of high quality, Larry is the man! Also for clarification, the trannies come from the supplier with the hammer tone finish. The chassis has to be painted.

[M Fowler]

Thanks Barry and I will get that bias down to -36ma as suggested per email. My voltage chart guys shows -41ma and it needs to be around -36ma with the 478 plate voltage.

Mark

[soma_hero]

You could use a switching scheme like mark huss and Dana use.

check out http://mhuss.com/18watt/schematics/MosfetSwitch1_1.gif

uses a solid state relay. Your footswitch will activate the relay that can switch the fast/grad. This way no need to fool around with isolating AC from signal, and from having your signal run down 40' of cable needlessly.

[M Fowler]

That looks good but not sure if that is the same thing Allyn used for his. I did go back on search and found info on his switching but it seems different to me.

Mark

[Structo]

Mark,
I'm glad this build worked out well for you. You did a fine job on it. As far as a footswitch add on for the preamp gain function, I know Allyn has implemented this but I don't have much to share on it. Maybe he will jump in here with some details. If not, It wouldn't be hard to install a footswitch jack that bypasses the toggle switch and allows a switching device to do the work with a foot pedal.

Be aware that as the original switch is wired, it not only has the preamp AC signal from the previous stage present on the terminals, but also the plate voltage. This is really not necessary since the only thing the switch is doing is either sending the full AC signal to the next stage or attenuating it some through the 82k resistor. The switch output then goes to the 0.1uf coupling capacitor which blocks the DC plate voltage from the previous stage and only allows the signal to pass.

I have attached a drawing that shows how to put only the signal on the switch by using two 0.1uf caps prior to the switch and eliminating the one downstream as it becomes obsolete. This was communicated to me from Allyn. The 1 meg resistors shown in the drawing eliminate switch pop. With this mod (and a switching jack) you could then add a switching relay assembly of some kind to implement the foot pedal.

At the moment I am heavily involved in my new solar energy business, but if I find the time in the near future I will attempt to put a drawing together for it. I do think Allyn has the full scenario, however.

Have fun playing that amp, and Larry, the cab looks awesome. For all of you guys looking for a cab of high quality, Larry is the man! Also for clarification, the trannies come from the supplier with the hammer tone finish. The chassis has to be painted.

For footswitch control of this, you can't just run the switch wires from that part you have pictured to the footswitch can you?

You need to use a relay of some sort?

[Tonegeek]

For footswitch control of this, you can't just run the switch wires from that part you have pictured to the footswitch can you?

You need to use a relay of some sort?

It would be VERY dangerous to run the switch as originally wired to a footswitch since it would carry the plate voltage too. With the altered version you would only be running the AC signal, but most likely it will pickup some hum even with a shielded cable and it will also alter the tone from the cable capacitance (could be a good thing in some cases). This is the reason relays are used for switching channels, gain boost, etc., plus it is just safer with a relay in case a cap goes out.

[bnwitt]

For footswitch control of this, you can't just run the switch wires from that part you have pictured to the footswitch can you?

You need to use a relay of some sort?

Yes of course. The drawing I attached is only to show how to get the plate voltage off of the switch. You would need a switching jack setup to bypass the switch when the foot pedal was plugged in, and a relay to do the switching with the pedal as the controller.

[M Fowler]

Got my cab from Distortions today and what a cab.

In my red cab for last Saturday's gig and in its new home today.

These pictures are nothing like seeing it in person.


Mark