[muletrane]

You guys got me on a search for the G-man's rig and I've been looking at ebay for a Mac. Not sure I want to spend the 600+ for one yet. Would I be able to accomplish the same thing with my Twin by installing a master? Where in the circuit could I install it to get the same effect as his rig? I'd like to run the preamp volume high and then tame the volume with the poweramp.
Also I read somewhere on this board that the preamp was hot going into the power amp. So would it work the same if I installed the preamp mod, routed it to the poweramp, and installed a master volume knob? I guess I'm fishing for some amp guru to help me get the same preamp/Mac setup in the chassis I already have.
Here's some pics of its current state: http://s468.photobucket.com/albums/rr46 ... an%20Twin/

[Imagined Days]

What's going on with those 2 preamp tubes? Also, I see you are running it with 2 output tubes. Are you only running 1 speaker? as for master volume. I put one after the two 220k resistors and before the .001 (.01 by my mod) phase inverter input cap. I did not like it, so i removed it.

[JonnyBoy]

I preamped my 65 reissue, which i a little different than the Part to part version you have. I have vibrato in my pre circuit, which is cool for me, I use it with a phaser for a rotary effect. The reverb is NOT working as of yet, and it doesn't work as a combo with tubes either right now, but a new 12AT7 tube will fix that, the reverb crashes when shaken on both taps, so it does work. So obviously, just those things proves the difference in my circuit than the part 2 part. Plus my pre is HOTTT. A P2P version may not be as hot as mine. I play it on 1 or 2 for clean, 3 to 4 for a little warmth pushing a little fuzz, 5 and above your getting grungy, but not full on distortion. Don't get me wrong, I love it. I am getting some new tubes, new caps and plate resistors so I am sure the sound will completely change, to what I dunno. Check out 65 twin reissue preamp mod thread for Waldo's suggestions on the mods.
As for the mac, some people use plug on wire adapters, 1/4" to RCA for input. Brad from SMS recommends using only one side of your mac for optimal tone from the amp unless it is a low wattage. If you are good with modding things, you can bust open your mac and change out the RCA inputs for a 1/4 input. To keep it on the resale market for top dollar, I'd use the adapters unless I never planned to sell it, but I never say never. guitar--> effects---> Pre-->mac--> speakers Is what I assume most people here do with that set up. PS, you don't need 400 watts per channel to get a good Garcia sound, an MC250 would suffice even for gigging. I don't use a Mac, but I use another clean 100 watt power amp. It gets louder than I can use.
A few well established musicians here use this set up, I am sure they can give you some first hand knowledge, after they get back from playing this weekend!!

[muletrane]

What's going on with those 2 preamp tubes? Also, I see you are running it with 2 output tubes. Are you only running 1 speaker? as for master volume. I put one after the two 220k resistors and before the .001 (.01 by my mod) phase inverter input cap. I did not like it, so i removed it.

It is currently wired like a Showman, i.e. no verb. Though I used to have it as a Twin. This amp has seen a bunch of revisions. I also have channel one modded with some dumble like mods, push pull boost on treble, jazz/rock switch, more mids. It has a Santana-like sound with the boost engaged. I like to pull the tubes for less volume and I do adjust the impedance (i.e. 8 ohm cab into 4 ohm tap). The merc output has multiple taps so I have a choice of speaker combinations.
The master you used, is that called a phase inverter master? What didn't you like about it? I haven't tried to install a master yet. I think there are different versions or different input points. Do you know which one would be closest to a preamp/power amp setup like a twin into a Mac? I'm not very knowledgable with circuits but don't mind tinkering to try things out. Thanks!

[muletrane]

I preamped my 65 reissue, which i a little different than the Part to part version you have. I have vibrato in my pre circuit, which is cool for me, I use it with a phaser for a rotary effect. The reverb is NOT working as of yet, and it doesn't work as a combo with tubes either right now, but a new 12AT7 tube will fix that, the reverb crashes when shaken on both taps, so it does work. So obviously, just those things proves the difference in my circuit than the part 2 part. Plus my pre is HOTTT. A P2P version may not be as hot as mine. I play it on 1 or 2 for clean, 3 to 4 for a little warmth pushing a little fuzz, 5 and above your getting grungy, but not full on distortion. Don't get me wrong, I love it. I am getting some new tubes, new caps and plate resistors so I am sure the sound will completely change, to what I dunno. Check out 65 twin reissue preamp mod thread for Waldo's suggestions on the mods.
As for the mac, some people use plug on wire adapters, 1/4" to RCA for input. Brad from SMS recommends using only one side of your mac for optimal tone from the amp unless it is a low wattage. If you are good with modding things, you can bust open your mac and change out the RCA inputs for a 1/4 input. To keep it on the resale market for top dollar, I'd use the adapters unless I never planned to sell it, but I never say never. guitar--> effects---> Pre-->mac--> speakers Is what I assume most people here do with that set up. PS, you don't need 400 watts per channel to get a good Garcia sound, an MC250 would suffice even for gigging. I don't use a Mac, but I use another clean 100 watt power amp. It gets louder than I can use.
A few well established musicians here use this set up, I am sure they can give you some first hand knowledge, after they get back from playing this weekend!!

Hey. That rotary effect sounds cool. Any phaser will work? Maybe there is a cold solder joint somewhere in the reverb? Thats usually what I think of when I hear something is loose. My goal is to be able to turn up the preamp to get some extra gain and sustain but to keep the volume down. I've tried a tube screamer before to get more sustain but do not like the tone. It sounds too much like an effect and I mainly like to plug in straight. I'm currently using a isolation cab and run my volume at about 3 with a push pull boost or about 4 to 5 without the boost and get some nice sustain but that is loud! It even comes through the iso cab and I think I'm about to piss off the neighbors. If your amp is louder with less ability to turn up the pre then I don't think this idea will accomplish what I want. Oh well.

[JonnyBoy]

Hey. That rotary effect sounds cool. Any phaser will work? Maybe there is a cold solder joint somewhere in the reverb? Thats usually what I think of when I hear something is loose. My goal is to be able to turn up the preamp to get some extra gain and sustain but to keep the volume down. I've tried a tube screamer before to get more sustain but do not like the tone. It sounds too much like an effect and I mainly like to plug in straight. I'm currently using a isolation cab and run my volume at about 3 with a push pull boost or about 4 to 5 without the boost and get some nice sustain but that is loud! It even comes through the iso cab and I think I'm about to piss off the neighbors. If your amp is louder with less ability to turn up the pre then I don't think this idea will accomplish what I want. Oh well.

In your P2P version of the amp, meaning you don't have a computer chip PC board attaching the guts, for some reason the preamp taps loose the vibrato, always. Since mine is a modern day PCB set up, they have tweaked the circuit, Not on purpose, so that reverb and vibrato come through with the tap. My reverb problem is the tube, I have to get new ones, they are all almost 17 years old and used and sound bad. Waldo and I have found some strange cap and resistor switching in the reissue circuit that is different than the vintage P2P versions. And that's only looking at the preamp circuit. I am sure they have more going on. So my preamp will be different in terms of what works and what doesn't after the tap.
All of the pre taps make your rig louder than just using the amp. That's a good thing. I think the consensus on the extra master volume knob is to loose it from the circuit, although some like it. Waldo has a lot of information about this, look up his website and check out the mods and taps. He has done his homework to give us all a look into Jerry's equipment.

http://www.wald-electronics.com/

[Imagined Days]

Yeah, I think it must be a pre phase inverter master volume, because it goes right before the P.I. input cap. It sounded thinner to me, and the preamp breakup was to edgy, not muical at all......sterile.