T-500 headphone jack and stock speakers simultaneously?

[OrganFreeman]

Hello all! This came up in my last thread and I thought I’d just start it as a new topic.

my question is: how do you get the T-500 to play from the stock speakers and out of the quarter inch headphone Jack at the same time? The Jack has a feature that cuts sound to the stock speakers when installed. I’m guessing there’s just one wire on the headphone Jack that I need to disconnect/unsolder? If so which wire is it? If not please advise if you know how to go about this. Thanks!

[Brendon Wright]

It's been so long since I've played around in there, and it's HIGH TIME my own T500 was brought back into use...
...but I can see in the attached pic that the only wire in common is the one running from C430 to the headphone jack.
I'm only partially literate in regards to electronics, but I THINK it shows the signal runs between the two amplifier pins 21 and ground on 20.
Normally unplugged the headphone socket completes the circuit to the speakers but when plugged in it removes the connection to C430, leaving the speakers only connected at one end, ground on pin 20.

Now, because I'm not fully literate, I don't know if it's bad to have both running at the same time or not, BUT, if you run a wire between both of the headphone signal terminals (but not the ground terminal) then they're both always live. You could put a little toggle switch in there and make it a switchable option, even.

[OrganFreeman]

Awesome! Thanks Brendon Wright So I just solder a wire in between the positive and negative terminals on the headphone Jack and that should do the trick then?

[Brendon Wright]

No, you'll notice there are two positive terminals on it. if those are both connected together it'll work.

[Brendon Wright]

In essence, if C432 is connected to C430...

[Brendon Wright]

Just so you know, if the signal (+) gets sent to ground (-) it'll stop the signal altogether.
I think many amps also really don't like that happening.

[OrganFreeman]

Thanks Brendon Wright! Will give this a shot and see!

btw I notice you are from New Zealand. Have you heard of the band Ticket or Space Farm? New Zealand had a tremendous heavy psych scene in the early 70’s and these bands have changed my life :).

[Brendon Wright]

Things were certainly more happening back then! I haven't actually heard of those bands (Mmmmmaybe ticket? Vaguely.)
There was something about being a big fish in a small pond back then.
Now communication and transport are so much easier we're all small fish in the ocean and give up before we start.

[OrganFreeman]

Did it and it works! Thanks man!

[Brendon Wright]

So excellent! I'm very glad about that.

[OrganFreeman]

So now that I got that mod made I’m running from the headphone Jack to a Dukane tube pa head into an altec 418 speaker. I’m gonna hook up another cab and run it on 4 ohms for the 2 cabs. The question now is, for my second cab do you think it would sound better to have a cab with a horn (a 15” altec 422 + horn to be exact?

just wondering if the horn would sound better in the organ application? The altec 422 id run it together with is surprisingly very dark and low and lacking high end / treble. I disconnected the horn to use with guitar. Should I hook it back up and use the horn / 15” speaker combo for organ? Or just the 15 alone without a horn?

[kziss]

The question now is, for my second cab do you think it would sound better to have a cab with a horn (a 15” altec 422 + horn to be exact? just wondering if the horn would sound better in the organ application? The altec 422 id run it together with is surprisingly very dark and low and lacking high end / treble. I disconnected the horn to use with guitar. Should I hook it back up and use the horn / 15” speaker combo for organ? Or just the 15 alone without a horn?

The best way to determine this is by connecting the horn and to then listen to the resulting tonality.
The horn will increase the brightness of the sound along with the key click and the leakage airiness, as well as helping the overall sound to come closer to that of a Leslie cabinet with the stopped motors.

If the sound of the horn is too bright or too shrill sounding, you can tame it down by adding a cotton ball in the horn throat, if the throat is accessible.

You could also wire up an L-pad speaker volume control to the horn so that you can bring down the volume level of the horn to better match with the bass speaker.

[Admin]

Posts on the NZ heavy psych scene have been moved to there own topic here:
NZ Heavy Psych Scene - The Organ Forum