Power amp input

[chocopower]

Hi there!

I would like to add a "power amp in" to my Pro-Reverb clon.

Looking at the schematic, i think a good place could be before the P.I. input cap (.001uf in my amp)...

Would this work?

[pdf64]

Hi chocopower, that would work but you will need a big signal to drive the power amp from there, maybe 2 to 3 V rms for full power. You need to go back another stage to get good sensitivity, but by the time you've done that you might as well just use a regular input, maybe use the lower sensitity input to keep it clean.
Hope that helps - Peter

[chocopower]

I want to run my POD direct to the power amp and using a A/B box, my guitar to the main input.

Isnīt the POD enought hard to drive this input?

[pdf64]

I think that the pod will not be loud enough to get full power from the Pro power amp if you send the signal in at the phase splitter.
Instead, think of your normal channel as a power amp input, but with the benefit of tone and volume controls. I think that you will get a much better sound like that than if you make a special line level input for your power amp. Because guitar speakers are muffled compared to hifi / studio monitor speakers, so you need a little treble boost from the tone controls to equalise for that. Peter

[stokes]

If you look at a schematic for a Mesa Boogie MKII you will see a good place to put a power amp in jack.But as pdf64 pointed out you will only get out of it what you out in.These jacks are meant to use a full power external preamp.Not familiar with the Pod,but if it is meant to be used in front of an amp,or at the input,it likely doesnt have enough power to drive the power section of your amp.Going into the PI would be the place to put it,tho.

[chocopower]

If you look at a schematic for a Mesa Boogie MKII you will see a good place to put a power amp in jack.But as pdf64 pointed out you will only get out of it what you out in.These jacks are meant to use a full power external preamp.Not familiar with the Pod,but if it is meant to be used in front of an amp,or at the input,it likely doesnt have enough power to drive the power section of your amp.Going into the PI would be the place to put it,tho.

Thatīs were i was thinking put it...
What should i use? A single wire or a shielded one (with shield grounded in the swicht)????

[stokes]

Think Mesa just uses a single wire with the jack grounded via the chassis/jack connection.

[chocopower]

Hi there!

i tried this mod last night!

Just one question... without nothing conected to the "power amp imput" it makes a loud hum. As soon as i put the POD, hum stops.
I conectec the tip to the P.I. cap and ground the swicht in the speaker output ground...

anything is wrong?

[Paleo Pete]

Wish I had seen this earlier, I use the Normal channel in the way PDF described earlier, with a Fender Super Reverb, it works great.

My situation was a bit different, I have a dual amp rig with an A/B switch going to each amp, one for clean sound and one for raunch n' roll. But I also have a lap steel I wanted available without having to unplug an input cable and plug the lap steel in. (and while the regular guitar is in use, switch to lap steel for a solo, back to regular guitar for the song, no time to stop and plug in) So I use the Normal channel instead. No extra noise, great sound, and it has its own tone controls.

For your situation it would work just as well with a slightly different setup. You would need an A/B switch and another guitar cable. One side of the A/B switch out into the pod and into the Reverb/Vibrato channel, the other side just a cable into the Normal channel. Or the opposite, depending on whether you want the reverb available with the Pod or not. No extra hum, separate tone controls for each channel and it works really well, I use it every time I get onstage but with a completely separate guitar rather than as a separate routing for the effects..

My opinion would be remove the mod, get the amp back to normal and invest in an A/B switch, I've been very pleased with the way my Super Reverb handles it. I never dig out a soldering iron if I can get what I want without modifying the amp. In your case the A/B switch would get you what you want, why take chances with the circuitry?

As far as your last question about the hum, I'm just guessing, but any time hum is an issue the first thing I look for is a ground problem.

[chocopower]

i already have an A/B box. The way you talk is as i have been using it last year.

The problem is that my Normal Channel no more the Normal Channel. Now is a tweed channel with a fat and punch sound. The problem is that to use it with the POD i need dial a really dark sound in this channel to compensate the PODīs bright... thats the reason for the power amp imput!
Last week i bought a midi router (8 loops) in e-bay and iīm gonna use it as an A/B/C box... a lot of posiblities......


i,m gonna try the power amp imput again....

thank, anywere...