SHP and Mic (Aux?) input

[dalton]

Looking over the schematics I noticed that the mic input has a pin that goes to each channel, 1 pin for a ground, and 1 pin for the -32v.

I assume the -32 was to power the microphone that was originally sold to allow paging and announcements, and I know that to allow the use of the microphone while there wasn't a record playing the inputs would go in after the preamp stage.

My question, is there any reason that I couldn't get a molex connector pinned properly and connect that to a sturdy aux cable with a bluetooth receiver left plugged in and tucked out of the way inside the jukebox? I understand that it will skip the tone shaping that's in the preamp.

Thank you,

Dalton

[Ron Rich]

Hi Dalton,
I assume that you could do that--but the power going to the mic is about -23vdc-not -32--- Let me know if that works ! Ron Rich

[dalton]

Ron, you sure about that voltage? It shows it -32v on connector J5112. Pg. 52 in Tony Miller's book

I did it quick and dirty to test it by stripping an aux cable. It sounds flat, but a little EQ magic fixes that right up. I'll get a proper connector tomorrow or Saturday when I can make it to an electronic store.

[Ron Rich]

Tony's correct-I was thinking it was reduced by a resistor--but that was on the older model amps-- Ron Rich

[robnyc]

Dalton, I've been converting both TSA and SHP amps for MP3 line inputs in both my home and commercial locations.

This link shows the method I've chosen:

www.flickr.com/photos/90641375@N06/40135321173/

The advantage here is that it leaves both AGC and post-EQ tone control available along with the volume/RVC functions.


Two points here:

- Because the input discussed here are after the preamp input stage, the "protection" circuits have no control.

- Remember that the overall tone shaping as designed greatly reduces bass boost as the volume control turns higher. Near maximum setting the bass is actually lower due to the thin EQ in the preamp. This lessens the load on the speakers and amp. If you are using an external device don't go overboard with bass boost and don't go too deep. The SHP's I have use a bass peak in the output stage of about 72Hz and gradual rolloff of about 4 db by 30Hz, again, to protect the speakers and maximize amp power bandwidth.

RobNYC

[dalton]

Rob,

Thank you for the reply. I was looking for something just quick and easy, so went for the molex plug.

I have saved your link and will give it a try next time the amplifier is out of the cabinet (most likely soon when I get around to dusting it). Keeping the AGC would be a nice feature, along with the phono volume controlling everything.

Regarding the points:

1. Noted. I'll make sure everything is neat when I do.
2. Thank you for the warning, I certainly don't want to go through the expense of reconing speakers a second time. Funny enough it's the treble I needed some more of. It's in a residential environment so I won't be cranking it too loud, just wanted a more balanced sound from it.


Unrelated, but thank you for the link. I used to have your photobucket page bookmarked with all the helpful info you had one there, then it was deleted. I assume because of the policy they started not too long ago. Glad to see all the info found a new home!

Thank you both Rob and Ron.