supergun line level sound out

ttooddddyy · Nov 25, 2003

A question for the supergun experts.
How do you guys tap the audio out on mvs. Im building a supergun and would like line level stereo out. Do you pot it from the audio output L & 10 or what ? Maybe the inputs to the HA 13001 are of sufficient level ?

Yodd · Nov 25, 2003

ttooddddyy said:
A question for the supergun experts.
How do you guys tap the audio out on mvs. Im building a supergun and would like line level stereo out. Do you pot it from the audio output L & 10 or what ? Maybe the inputs to the HA 13001 are of sufficient level ?

I assume you are doing this with a stereo multislot board?

If so, you can tap the audio for Left from pin L and Right from pin 10 and then run them through a simple resistor voltage divider circuit:

Full article HERE

And you can read a thread on its use @ SGR

Several of us have used this and it works well to attenuate the audio by about 20dBs.

Build 2 of them; one for each channel.

Matt · Nov 25, 2003

Be aware that this will only work on setups where the negative speaker line is grounded. It'll work on the MVS, but will fry most JAMMA boards that have actively driven Speaker + and - lines.

In a case like that, you'll want a "line level converter", which can be found at many car part shops.

norton9478 · Nov 25, 2003

IT WILL WORK ON jamma boards.....

Just make sure that you are gounding the item to the ground and not the - terminal...

If using a jamma/ monomvs board, ignore the - terminal... Don't hook it up to anything but speaker out....

the - terminal on an RCA jack (outside) goes to the ground. The ground off the at circut goes to the ground. The negative terminal goes to squat.

I just tested it with my kageki board...

ttooddddyy · Nov 26, 2003

Thanks for the info guys, I rekoned on a simple potential divider but wasnt shure what values to use.

On jamma boards isnt pin 11 a pre-amp out. If so it would be a way around the jamma + - speaker issue on some boardsets.

norton9478 · Nov 26, 2003

as far as I know... Most Jamma boards don't use PIN 11.... I never had one that did.....

NGT · Nov 26, 2003

I use attenuation circuits on my super guns but I have to put in two of them. One is for split mono if you want to use a jam a board which only comes off of the 10 pin and the other one is for a wire coming off of the L. pin which will then run through a switch they can be used to go back and forth between split mono for jamma boards and stereo MVS boards.

MKL · Nov 26, 2003

ttooddddyy said:
A question for the supergun experts.
How do you guys tap the audio out on mvs. Im building a supergun and would like line level stereo out. Do you pot it from the audio output L & 10 or what ? Maybe the inputs to the HA 13001 are of sufficient level ?

MVS boards output line level audio from this circuit:

Code:

                                          _|_|_|_|_|_|_|_
                                         |               |
                                          )   BA10324    |
                                         |_______________|
                                           | | | | | | |
                                           | |       | |
                                           | |       | |
                           4.7 uF          | |       | |
                    |--------)|------C--------        ------------|
                    |                                             |
                    |                                             |
          2.7 kOhm  |       4.7 kOhm                              |
  R ------/\/\/-----A--------/\/\/------|                         |
                                        |                         |
                                        |------- Jamma pin 11     |
          2.7 kOhm          4.7 kOhm    |       (unampl. mono)    |
  L ------/\/\/-----B--------/\/\/------|                         |
                    |                                             |
                    |                                             |
                    |      4.7 uF                                 |
                    |--------)|------D----------------------------|

This is based on an older model 4-slot. Other boards may differ slightly. R and L are on the headphone volume slider, NOT the speaker connector (which is not line level). However, tapping the signals from R/L will result in an extremely quiet output: you'll have to crank the volume all the way up on the TV/receiver. Tap them from A/B or C/D and you'll get a definitely louder output but you still have to increase the volume on TV/receiver quite a bit though. As you see, jamma pin 11 is R and L filtered by 7.4K each and subsequently tied together. The sound off that pin will be too damn quiet (and mono!).

For a general purpose supergun I also recommend not to use pin L for ground for the simple reason that on several boards (Capcom, etc.) that's not a ground. As for the attenuation circuit, I have to say that I don't consider it that important. The risk of blowing speakers is not high at all since you don't crank the volume all the way up on the boards themselves. And as far as I could see the heat sink doesn't get any warmer that way. Also, I've seen a very well made Japanese supergun called Twin Rudder (similar to the Vega jr) where the sound was straight off the jamma connector, without any line level conversion or attenuation circuit...

ttooddddyy · Nov 26, 2003

Thanks for that MKL.
So the BA10324 is a buffer/driver for the headphone outputs before the inputs to the HA 13001 output stage?
Im looking at a MV-1 at the moment and dont see a BA10324.
What Im trying to achieve is a general purpose sgun for mvs and jamma boards. I was thinking Id need a mvs/jamma speaker out switch for this.
I realise that L is not always ground on jamma boards, there seems to lie the problem.

MKL · Nov 26, 2003

ttooddddyy said:
Thanks for that MKL.
So the BA10324 is a buffer/driver for the headphone outputs before the inputs to the HA 13001 output stage?
Im looking at a MV-1 at the moment and dont see a BA10324.

The BA10324 is a quadruple op amp that may be replaced by two BA4558 dual op amps on other boards. Yes, the above circuit is independent of the HA13001: points C and D of the above scheme (older 4-slot) separately go to the inputs of the HA13001 (pins 3 and 4) through a 4.7k cap, 100ohm resistor and the speaker slider.

ttooddddyy · Nov 26, 2003

OK on the MV-1 there are actually 4 X 4558 op-amps around that stage. I think the 6 slots are similar.

supergun line level sound out

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