Hi,

I've been upgrading an existing sound system by adding a mixing
desk.This has +4dBu balanced outputs, (It's a Soundcraft Spirit) but
I'm trying to connect to an existing 100V line amplifier. What is the
best way to go about this? The amp has input connection as follows...

600 ohm, 0.5mV balanced,
600 ohm,0.5mV unbalanced
50Kohm, 2mV, unbalanced
220Kohm, 100mV unbalanced
10Kohm, 100mV unbalanced

Which one should I use, and how should I wire up the connection? I'm
reasonably confident with a soldering iron if I need to add some
resistors, but I'm not averse to turning the gain down if that's all
that's required.

Thanks,

Tristan

Fred Basset wrote:

I've been upgrading an existing sound system by adding a mixing
desk.This has +4dBu balanced outputs, (It's a Soundcraft Spirit) but
I'm trying to connect to an existing 100V line amplifier. What is the
best way to go about this? The amp has input connection as follows...

600 ohm, 0.5mV balanced,
600 ohm,0.5mV unbalanced
50Kohm, 2mV, unbalanced
220Kohm, 100mV unbalanced
10Kohm, 100mV unbalanced

Which one should I use, and how should I wire up the connection?

I think the 10K ohm 100 mV input is probably your least worst choice.
Check the manual for the recommended method of connecting the outputs
to an unbalanced device. You may need to tie Pin 3/ring to ground (Pin
1/sleeve) or you may need to leave it open and just connect Pins 1
(ground) and 2 (hot) to the amplifier inputs.

You'll probably find that the mixer outputs are rather "hot" for this
amplifier. You can either run the masters low if you don't care about
having a usable VU meter indication and aren't also recording the mixer
output, or you could put a 20 dB or so attenuator (pad) between the
mixer output and the amplifier input. There's some handy design info at
http://www.uneeda-audio.com/

If the mixer also has a -10 dBV unbalanced output, that would be the
best route.

"Mike Rivers" wrote in message
oups.com...

Fred Basset wrote:

I've been upgrading an existing sound system by adding a mixing
desk.This has +4dBu balanced outputs, (It's a Soundcraft Spirit) but
I'm trying to connect to an existing 100V line amplifier. What is the
best way to go about this? The amp has input connection as follows...

600 ohm, 0.5mV balanced,
600 ohm,0.5mV unbalanced
50Kohm, 2mV, unbalanced
220Kohm, 100mV unbalanced
10Kohm, 100mV unbalanced

Which one should I use, and how should I wire up the connection?

I think the 10K ohm 100 mV input is probably your least worst choice.
Check the manual for the recommended method of connecting the outputs
to an unbalanced device. You may need to tie Pin 3/ring to ground (Pin
1/sleeve) or you may need to leave it open and just connect Pins 1
(ground) and 2 (hot) to the amplifier inputs.

You'll probably find that the mixer outputs are rather "hot" for this
amplifier. You can either run the masters low if you don't care about
having a usable VU meter indication and aren't also recording the mixer
output, or you could put a 20 dB or so attenuator (pad) between the
mixer output and the amplifier input. There's some handy design info at
http://www.uneeda-audio.com/

If the mixer also has a -10 dBV unbalanced output, that would be the
best route.


if this is a typical 100V paging type amp it should have a line level input
somewhere on it. maybe an RCA connector. it might be labeled "bus"

TimPerry wrote:

if this is a typical 100V paging type amp it should have a line level input
somewhere on it. maybe an RCA connector. it might be labeled "bus"

With a description of the inputs that complete, I would have thought
he'd ask about any other jacks that might be inputs. But I don't think
it's unreasonable for the "line" input to be in the ballpark of -20
dBV. That's the typical output of a consumer phono jack output, not -10
dBV like "semi-pro" studio equipment that TASCAM broght us.

"Mike Rivers" wrote in message
oups.com...

TimPerry wrote:

if this is a typical 100V paging type amp it should have a line level
input
somewhere on it. maybe an RCA connector. it might be labeled "bus"

With a description of the inputs that complete, I would have thought
he'd ask about any other jacks that might be inputs. But I don't think
it's unreasonable for the "line" input to be in the ballpark of -20
dBV. That's the typical output of a consumer phono jack output, not -10
dBV like "semi-pro" studio equipment that TASCAM broght us.


on some models the same point is both an input and output and can be used
for recording or as an AUX in or to link 2 units together.

if the poster would care to divulge the make and model we could do something
beyond speculation.

TimPerry wrote:

if the poster would care to divulge the make and model we could do something
beyond speculation.

For some reason, that almost always only comes after some prodding.