I have a Haffler DH220 that I want to recap. While I'd doing that, I'd like to use an integrated amp to replace it. The Haffler will likely be on the bench for a few weeks while I make a parts list, order parts, and in general find the free time to do the maintenance on it.
I'm pretty sure I can just run a pre-amp into an input on the integrated amp and set the volume control on the integrated amp to some fixed level (say 3/4).
In looking at the schematic for the input section of the integrated amp (first attachment), it looks like the signal pass is from the input to a buffer (2604 op-amps, U1A/U12) and then to the attenuator (the LM1972, U22). The outputs from the attenuator go to another set of buffers and then on to the amplification stages (2nd attachment).
Since the LM1972 only attenuates and doesn't have any gain, this seems like a safe bet....but I thought I'd check first.
Thanks,
James
I'm pretty sure I can just run a pre-amp into an input on the integrated amp and set the volume control on the integrated amp to some fixed level (say 3/4).
In looking at the schematic for the input section of the integrated amp (first attachment), it looks like the signal pass is from the input to a buffer (2604 op-amps, U1A/U12) and then to the attenuator (the LM1972, U22). The outputs from the attenuator go to another set of buffers and then on to the amplification stages (2nd attachment).
Since the LM1972 only attenuates and doesn't have any gain, this seems like a safe bet....but I thought I'd check first.
Thanks,
James
Attachments
Your schematic is woefully incomplete, but Preamp signal path seems to end at J6 , labelled L-R so presumably "Preamp Out"
I GUESS (you give us no other option) that there is another pair of Audio connectors (RCA?) labelled L-R Power Amp IN
Often such OUT-IN pairs are side by side and joined by U shaped wires.
If so, remove those bridging wires and plug your preamp into that Power Amp IN.
Mind you: you are showing us INCOMPLETE schematics, NO Brand and Model, NO back panel (connectors) pictures, NO user manual.
You ask too much offering very little data.
I GUESS (you give us no other option) that there is another pair of Audio connectors (RCA?) labelled L-R Power Amp IN
Often such OUT-IN pairs are side by side and joined by U shaped wires.
If so, remove those bridging wires and plug your preamp into that Power Amp IN.
Mind you: you are showing us INCOMPLETE schematics, NO Brand and Model, NO back panel (connectors) pictures, NO user manual.
You ask too much offering very little data.
Why can't you just connect an RCA cable between the preamp main output,
and one of the line inputs on the integrated amp?
Or just connect your sources directly to the integrated amp?
and one of the line inputs on the integrated amp?
Or just connect your sources directly to the integrated amp?
@Rayma, That is essentially my question: Can I just connect the output from the pre-amp to the line inputs and then just use the volume control on the pre-amp.
For your second question, well it's not actually a preamp. It's a streamer with an integrated preamp (Bluesound Node 2), so it's actually both the source and the preamp. While it does have a line out, all the gear is stashed out of sight in a closet and controlled from an iPad. I wouldn't have a way to access the volume control.
@JMFahey, I've attached the complete schematic, though I don't think it is really necessary for the question. What I provided before shows the the signal path from the input to the amplification stage. The amp is a Primare i20. It does not have a jumper from the pre-out to the amp-in, so not easy way to by-pass the pre-amp. I thought about just backfeeding through the pre-out, but that looks like it would cause the buffer op-amps to be active trying to keep it's non-inverted input at the same level as inverted input, which would be driven by the signal from the external device. Probably wouldn't hurt anything, but didn't strike me as a good idea.
For your second question, well it's not actually a preamp. It's a streamer with an integrated preamp (Bluesound Node 2), so it's actually both the source and the preamp. While it does have a line out, all the gear is stashed out of sight in a closet and controlled from an iPad. I wouldn't have a way to access the volume control.
@JMFahey, I've attached the complete schematic, though I don't think it is really necessary for the question. What I provided before shows the the signal path from the input to the amplification stage. The amp is a Primare i20. It does not have a jumper from the pre-out to the amp-in, so not easy way to by-pass the pre-amp. I thought about just backfeeding through the pre-out, but that looks like it would cause the buffer op-amps to be active trying to keep it's non-inverted input at the same level as inverted input, which would be driven by the signal from the external device. Probably wouldn't hurt anything, but didn't strike me as a good idea.
Attachments
So connect the streamer output to the integrated line input.
Set the streamer volume to the middle of its range. Try it and see,
using the integrated volume control.
Adjust the streamer volume, up or down, to get a normal volume control
working range on the integrated amp.
Set the streamer volume to the middle of its range. Try it and see,
using the integrated volume control.
Adjust the streamer volume, up or down, to get a normal volume control
working range on the integrated amp.