Peachtree Audio Nova - No subwoofer connection

ZD, with nearly all systems you would be correct, but not in this case.

Jim (Broadstone), I'll start with what is most important:

DO NOT CONNECT THE SUB TO THE OUTPUTS OF THE PEACHTREE 220 AMPLIFIER, unless Peachtree says it's ok, and they have said that it's not ok. I and Kijanki explained the reasons in this thread.

Although powered subs which provide speaker-level inputs almost always do in fact incorporate attenuation circuitry to reduce the signal level provided to the sub's amplifier, and although such subs almost always provide a very high input impedance to a power amplifier they may be connected to (resulting in negligible loading), the design of your specific amplifier appears to completely rule out the use of that kind of connection. At least without the use of a very specialized adapter incorporating DC blocking capacitors, as explained in the other thread.

Regarding connection of the sub to the preamp, can you tell us the exact model name or number of the Peachtree Nova? If it is this one, for example, it appears to have two individually buffered sets of outputs, each having low output impedance. Connecting one to the power amp (preferably Pre Out 1, which is described as being "discrete class A") and the other to the sub should work fine in that case. Aside, perhaps, for subtle possibilities such as ground loop issues that may arise when interconnecting three components.

Best regards,
-- Al

Jim, I couldn't find an output impedance spec on the pre-outs of the Nova 80W integrated. However the Nova 65SE, 125SE, and 220SE all have the corresponding output impedance specified as "< 50 ohms." Assuming your Nova is similar in that respect, I don't know why it wouldn't be able to drive your power amp (which has a very high input impedance) and the sub at the same time, without perceptible sonic degradation.

I recall from the other thread I linked to that you have a multimeter. What I suggest is that you set it to measure DC volts, and while the amp is powered up but no music is playing measure the DC voltage between each of the output terminals of the amp and the ground sleeve of an RCA input connector on the amp. You can do that while the amp is connected to the speakers and the Nova.

If you measure a high voltage, such as 40 volts, that rules out use of speaker-level connections to the sub, at least without the specialized adapter I referred to. If you read a tiny fraction of a volt, then an approach that should work would be to connect the positive speaker-level inputs of the sub to the positive output terminals of the amp, and to connect the negative speaker-level inputs of the sub to a ground point on the amp. The chassis of the amp MIGHT be a suitable ground point, but a surer bet would be the ground sleeve of an RCA connector, or pin 1 of an XLR connector.

Good luck. Best regards,
-- Al

P.S: Subsequent to submitting the previous post, I did find an output impedance spec for the pre-outs of your Nova 80W integrated, that spec being "<30 ohms." So, again, I don't know why it wouldn't be able to drive the sub and the amp without sonic degradation.

Best regards,
-- Al

Good news, Jim! Thanks for the update.

Another reason you may have been hesitant to accept the idea of a splitter might be the many negative comments about them you may have seen here in the past. Although on occasion positive ones do appear.

My belief, though, from a technical standpoint and also based on having used them at times over the years, is that the adverse effects people often seem to report as a result of using them are in most cases due to the inability of the component providing the signal to simultaneously drive two sets of cables and the two specific load impedances with good results. Rather than being caused by the splitter or y-adapter itself. And/or failure to realize, in situations where a preamp output is split to drive both a power amp and a sub, that the capacitance of the cable to the sub as well as the input impedance of the sub will affect the signal seen by the power amp. To a degree that may or may not be significant depending on the specific numbers that are involved.

As I indicated earlier, though, those factors don't appear to be applicable in your specific situation.

Best regards,
-- Al

B_limo, it's hard to say which approach would be better in your case. I suspect that either one would work reasonably well.

I assume you are referring to the Asgard 2, as the earlier version does not appear to have provided pre-outs. Although I suspect that the <2 ohm output impedance spec that is provided for the Asgard 2 applies just to the headphone output, not to the pre-outs. But I would expect that the pre-outs on that unit probably also have fairly low output impedance, and the input impedance of the Classe CA-150 amplifier listed in your system description (assuming you are still using it) is a high 75K. So even if the input impedance of the sub's line level inputs is fairly low, as is often the case, the Asgard 2 most likely would have no trouble driving both components. And hopefully the cables you would be using to connect the sub and the Classe to the Asgard if you went with the line-level approach would not be unusually long.

In making those comments about the line-level approach I'm assuming, of course, either that the sub provides line-level inputs for two channels, or that you would be using two subs. If the sub also provides speaker-level inputs for two channels, or if you would be using two subs which provide speaker-level inputs, connecting at speaker level should also work well. And some would say connecting at speaker level is preferable because the sonic character of the amplifier would be reflected in the signals received by the sub as well as the main speakers. Some would also say that connecting at speaker level is preferable because it avoids the use of a splitter, but see the comments in my previous post relating to that.

Also, although it's probably not applicable in your case, be aware that special considerations come into play when connecting at speaker-level if the amplifier is bridged, or has balanced outputs, or is a pair of monoblocks. And as you've seen earlier in this thread, in the case of certain class D amplifiers.

Regarding the choice between connection of the sub to the amp outputs or to the speaker terminals, it may not make much difference but my instinct would be to connect to the amp outputs. Conceivably that could be beneficial by reducing the amount of "back-emf" generated by the speaker drivers that could find its way into the sub. On the other hand, though, it is conceivable that doing so might increase the amount of electrical noise generated by the sub's amplifier that would couple into the feedback loop of the main amplifier, assuming it has a feedback loop, so who knows? As I say, it may not make any difference either way.

So I suspect that both a line-level approach and a speaker-level approach would work in a reasonable manner in your case. My instinct, especially if I am correct in assuming that the amp is not bridged, balanced, monoblock, or class D, would be to go with the speaker-level method, connecting to the amp output terminals. But when and if practicable consider trying the splitter approach as well, and comparing results.

Best regards,
-- Al