DR. Sluckey AB763vibrolite build..... Line out?

[Toxophilite]

A tremelo voltage question (again)
My tremelo works dandy
It's supposed to be supplied by 364 volts
I'm currently getting power from the "A' spot right after the choke. I was using a 10K resistor but I'm still getting around 405 volts
I was mistaken about my phase inverter voltage it's only about 325 volts
So I have 40 above or 40 below ( heh heh temperature extremes!)
Should I just use a bigger dropping resistor off the 'A' supply?

Is there a better or worse choice here ?
It works fine on both, it seems to be a fair bit deeper with the higher voltage

I just wanted to make sure that excessive or too little voltage wasn't going to be a problem(other than a difference in the tremelo depth)
Thanks

[sluckey]

Quit worrying about it and connect it directly to point "A" which is the screen B+ node. Fender always connected to that B+ node for all the tremolo circuits, regardless of what the voltage was. If you examine the Fender schematics you'll see that voltage as low as 346 and as high as 458. Just play it!

[Toxophilite]

I am I am!..I mean I was Iwas!!! for the last hour or so and I have been!
I was just thinking about it while I wired the tremelo footswitch jack earlier
Covering my @$$ so to speak
Thanks

[sluckey]

Now that looks like a true conversion project. I love seeing old stuff like this get a new purpose, especially if it makes guitar sounds. I've done 4 conversions in the last few years. One from an old jukebox amp, two from Hammond organ reverb amps, and one from an old radio. The radio conversion is my favorite. My wife even lets me keep it in the house. Take a look...

http://home.comcast.net/~seluckey/amps/RCA/RCA.htm

[Toxophilite]

Nice!
No wonder you get to keep it in the house!
What a fine job you did of incorporating it all in the original cabinet
Lot's of cool projects on your site.

i have a Hammond L-100 amp kicking around (now minus a choke!) that might be my next victim. It has one of those little cone boards in it

Thanks again

[sluckey]

i have a Hammond L-100 amp

That's the AO-43, right? They make a great Marshall 18W, Matchless Lightning, or any of the EL84 based amps.

[Toxophilite]

Now to decide between the matchless and the marshall
I was having a look at the matchless spitfire too
Though the matchless amps need a choke which I've stolen for the deluxe
I also have a small Bogen PA/record player amp that seems like it would be a good platform for one of those builds as well

Hey out of curiousity
Does changing preamp stage cathode bypass caps actually affect positive change in bottom end response?
Yet another thing I haven't any experience with.....I guess I could go get some haha

[sluckey]

Does changing preamp stage cathode bypass caps actually affect positive change in bottom end response?
Yet another thing I haven't any experience with.....I guess I could go get some haha

Experience is a good thing.   

[Toxophilite]

[Experience is a good thing.   

Truly!
And I had a vey good experience trying out my new little amp through my D130, playing with my 3 piece band . the drummer is a heavy hitter.
It sounded beeeeeaauutiful! Stayed clean right up to where I needed it with maybe a little room to spare
I've played the same 85lbs super reverb for the past 25 years
And for a good reason, it has a big sweet clean sound, however it'll be nice to have the option to carry a nice light amp for a change and still have it do the job.
I found the best result was achieved when I turned up the entire tone stack all the way and then turned down what I didn't want, mostly mids but a bit of everything.
I was very pleased , I got a nice big bright jangly sound out of it with quite a nice warm bottom....kind of like having heated car seats on a cold clear winter day.....or something like that
I've always wanted a deluxe but couldn't justify forking over lot's of $$$ to get one. Now I have one..huzzah!
I paid $30 for the console from a couple who just wanted it out of the basement, sold the cabinet for $50 as a piece of furniture (it was really pretty!)  and some other bits for another $25 which paid for all the parts and a couple of coffees.

Anyway, Thanks again!

Now I need to find another....STEREO! mmmmm

[Toxophilite]

Hey
Where would be a good place to put a line out on this amp
If I wanted to send the signal to another amp?
My super has one on the negative feedback circuit
Any reccommendations?

[sluckey]

I'd do it like this...

[Toxophilite]

Cool
THanks
On my build that's a convenient location too

[Toxophilite]

Hello
I was looking at this line out schematic and it seems to be more of a effects loop, requiring something to come back in for the amp to work.

Is is possible to have just a line out without a return and still have the amp operating?

I want to send a signal from this amp to another amp but I won't have a signal coming back

I'd use the other input jack trick but that drops down the signal I'm sending into the amp i a way I don't like

[sluckey]

Sure, just use a single jack and connect it parallel to the signal path. Don't use a switching jack

[Toxophilite]

 
Oh course, so simple
THanks very much!

[terminalgs]

Ampeg did what sluckey is suggesting and they labeled the jack "Ext. Amp".  On Portaflex amps, they installed one of these, on later SVTs, V22s, etc.. they installed two of these jacks.  both jacks connected the same way, in parallel.  The Ampeg "Ext. Amp" jack doubled as a 'preamp out', or a 'power amp in'.  When one SVT wasn't enough for your crew to set up on stage, you'd set up two, interconnect them with a patch cable between "Ext. Amp" jacks, plug your bass into one, and turn the volume controls on the second to zero. 

You can plug the "Ext. Amp" into the "input" jack of another too.  I suspect that is what you are envisioning. In the Ampeg owners manual, they described doing this and they also warned "set the second amplifier's controls very low".

Of course, the reason for that is the signal is super hot.  an amp is expecting to see a small instrument signal at the input jack, maybe  0.5Vrms  but the signal at that point in the amp can be 10V, 30V, 60V.

If you are labeling jacks on the back of amp that might be used by others, I'd pick "Ext. Amp". over "Line Out". :-)   People associate "line out" with "line level",,  which it ain't!.

You can also play with something like this:



Take the 270Kohm R14, and divide it into 2 resistors, making R2+R3=270K setting up a voltage divider to attenuate the signal.  if you can be a little loosey-goosey with R14's overall value, make your 270K R14 be R2, and make R3 be 22K or 10K.  dial it at the amp's max gain to produce whatever output level you want.

Also, R4 can be omitted if both amps are quiet noise-wise.  If you have increased hum it might be a ground loop set up by the 3rd "earth" prong on your power cords, plus the common ground via the patch cable.  If this happens, install a 10ohm R4, or even better: a 10ohm R4 plus a parallel .1 cap.   This will lift the ground enough to eliminate ground loops and still provide AC ground for the audio signal.
 

Another "line out" option is:


Fender, Gibson, and Ampeg all did this at one time or another.  make R2 be 100ohm or 150ohm, and make R1 be whatever is needed to attenuate the signal down to 1-2Vrms. value depends on the amps output, but might be 1K, 2.2K, 4.7K etc... R2 sets the output impedance, so making it 150ohm means it can be connected to another amp, a mixing board, PA, etc...