If you don't like that answer, then what I would suggest is getting an external amplifier (like an AudioSource 310) which has A+B outputs, connecting your main L/R speakers to one set of outputs, and your other speakers to the other set of outputs. The reason you've got a mismatch right now is you're driving a preamplifier output (which means variable with the Onkyo's volume control) into a preamplifier input - you're putting a lot of attenuation and tone control between the signal and the amplifier, dialing them both in is going to be consistently impossible if you want to adjust one/both of them independently (which is what you're experiencing). I know, you're upset over the delay, that's just a reality of the equipment you have - this is really the "ideal" or "proper" way to set things up. Couple to that that you'd be using a line level output which would make things work like they're supposed to work. If you're decoding a multi-channel source you are not getting the entire signal in whatever other area, you're just getting a piece of it - using a stereo output means you get the entire signal. Now, as to why I would not do the FL/FR output and use Zone 2 instead: Is that OK or do I need to put the split point further downstream and double any or all of R20, C11/R22?ĥ) I was going to use an NE5534 OpAmp for this, but have read it's not unity stable so was worried about using it in the first stage (hence the TL072 marked on the diagram).But he's sending the FL/FR to both the Onkyo's amplifiers and the Sony (I'll get to why I think this is a bad idea in a minute) - so wouldn't they be on the same gain control? (I know on every AVR I've ever seen those trims are not independent, because you're just adjusting the thing's "preamp" output, not the amplifier sensitivity) So specific questions I have are as follows:Ģ) Does the large feedback cap (C10) do what I think it will do and/or could it be a stability (or other) problem?ģ) Do my gain calculations make sense? And should this make the sub volume track the main speaker volume as I hope?Ĥ) The output of this is paralleled directly to two RCAs, in case I move to dual subwoofers in future. I may omit the first stage bypass cap, C9, as I'm not sure it's needed - but will keep the PCB space in case. I also included a larger feedback bypass cap, C10, on the second stage to give a roll-off point of 300'ish Hz. The circuit below (my understanding) has an inverting/summing stage of unity gain, followed by another inverting buffer with a gain of 4.7/1.5 = 3.13, matching the preamp close enough. The preamp buffer stage has 4k7/2k2 feedback resistors, giving a gain of 3.14 (1+4.7/2.2). The input switching side is a set of relays feeding a remote-control volume pot directly and that in turn feeds both a preamp stage (classic simple op-amp design) in parallel with the subwoofer summing/buffer circuit below. I'm designing an op-amp based input-selector/preamp with subwoofer output(s).
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