McIntosh & Marantz bi-amp JBL 1400 Arrays...

[tom1040]

Also, I had emailed the question to Marantz a while back to get their feedback. This is what they recommended:

Hello Tom,

Your configuration is possible except you will need an external electronic crossover. When the SC-7S2 is in Bi-amp mode you can use both the Balanced and Unbalanced outputs for each channel. Both outs will send a full range signal to your mono blocks. It will then be up to the speaker to filter the frequencies. If the speakers don't have built in crossovers then you will need an external electronic crossover to filter certain frequencies. At that point, the only option for a subwoofer hookup would be the Record Outs A+B. When the SC-7S2 is in Bi-amp mode both Rec Outs are active. Of course, the subwoofer needs to be an active (powered) sub and have its own internal crossover.

Thank you,

Technical Support / Custom Install
D&M Holdings NA

[grumpy]

Like this? Yes. Exactly that? Hard to tell if those are appropriate for audio equipment (could be based on 75 or 50 ohm radio gear vs the high(er) input impedance of your amps)... If not the correct type, they could potentially damage your preamp. The problem is attenuators are not system generic. If I can look them up and find out for certain, I'll let you know.

Do you know or did you check the operation of the rear panel attenuators on the Marantz amps, to see if they were stepped or continuously variable?

[grumpy]

The D&M response was interesting. Perhaps I misread it, but it doesn't seem complete or correct.
e.g., rec out signals do not normally follow the volume control, and you don't really need an active external crossover (except for the sub, which often has one built in).

[grumpy]

For as much as you have invested, it might be worth paying someone to come to your house and help you out. A passive-biamp main plus a sub, with parts from various mfgs, is not a simple thing.

[tom1040]

Like this? Yes. Exactly that? Hard to tell if those are appropriate for audio equipment (could be based on 75 or 50 ohm radio gear vs the high(er) input impedance of your amps)... If not the correct type, they could potentially damage your preamp. The problem is attenuators are not system generic. If I can look them up and find out for certain, I'll let you know.

Do you know or did you check the operation of the rear panel attenuators on the Marantz amps, to see if they were stepped or continuously variable?

Appears stepped in intervals of -3db.

[tom1040]

The D&M response was interesting. Perhaps I misread it, but it doesn't seem complete or correct.
e.g., rec out signals do not normally follow the volume control, and you don't really need an active external crossover (except for the sub, which often has one built in).

You are correct(again).



Hello Tom,

No, the Rec Outs output a fixed volume, so all volume control for the sub would need to done externally. The other possibility is using a powered RCA distribution box. This will allow you to split the signal from the Unbalanced Outs. One signal path will go to the mono blocks and the other would go to the subwoofer. You need a powered distribution box to keep the voltage at around 2V otherwise you would be sending a weak signal (1V) to the mono blocks and sub when the split occurs.

Thank you,

Technical Support / Custom Install
D&M Holdings NA

[tom1040]

For as much as you have invested, it might be worth paying someone to come to your house and help you out. A passive-biamp main plus a sub, with parts from various mfgs, is not a simple thing.

Perhaps you are right. Thanks to all who have helped.

[grumpy]

You could use a pair of these

http://www.mcmelectronics.com/product/555-8462

to provide variable attenuation for the pre XLR/balanced out,
since they seem to be ok with you combining balanced and single ended outputs.

If you try them and don't like them, I'd be happy to buy them from you to put in my "toolbox"

[tom1040]

I asked Marantz tech again if I could use the balanced and both RCA pre outs at the same time if I switch from 'stereo' to 'bi-amp' on the pre and this was the answer:

Response Via Email(NJ Customer Service & Support) - 06/05/2012 04:08 PM
Hello Tom,

Upon reviewing this again, you are correct. In "Bi-amp" mode you can use the Balanced Outs with one amp, the Unbalanced Outs (1) with another amp, and the Unbalanced Outs (2) to the sub. However, you will still need an external crossover to filter your LF or HF unless the speaker already has an external crossover built in.

Thank you,

Technical Support / Custom Install
D&M Holdings NA


So, I guess I could try it with the device you (Grumpy) pointed out, right? Or, would it be advisable to use a external crossover? As I was told by someone, modifying the speakers voids the 5 year warranty so I would perfer not to go that route if possible. Hell, I am not even sure if this is worth it in the end but it may be worth a try.

Thanks again to all you have given your suggestions. Perhaps, armed with this knowledge, it will make it easier for someone with a better skill set than I to make this work out.

One last thing, I want the Marantz for the LF-McIntosh for the HF. Which would need to be toned down?

[jblnut]

As someone who's been passively biamping some 250's for years, I can tell you pretty conclusively that it only makes a difference if the amps have a different sonic signature. I did it to put tubes on the high-end and maintain lots of SS power on the bass. You have two (three actually I think) very high quality SS amps. I am not sure you'd get a lot out of this honestly.

Can't hurt to try really, but there is not a whole lot to be gained in this case I'd wager.

jblnut

[tom1040]

As someone who's been passively biamping some 250's for years, I can tell you pretty conclusively that it only makes a difference if the amps have a different sonic signature. I did it to put tubes on the high-end and maintain lots of SS power on the bass. You have two (three actually I think) very high quality SS amps. I am not sure you'd get a lot out of this honestly.

Can't hurt to try really, but there is not a whole lot to be gained in this case I'd wager.

jblnut

I concur with you. The only issue that is stopping me for dropping this issue is the 'what if' factor. I have the gear-it is for sale-but what if it worked and worked well?

These Marantz monoblocks complete with the other reference gear(pre/sacd) sound great with the Arrays---further thought while listening today/tonight just confirms that.

[grumpy]

There would be no modifying the speakers if you -passively- biamp (use the speaker's internal crossover,
which can be used with two separate amplifiers simply by disconnecting the shorting straps between the
terminals). You have a manual and specs for the 1400's?

If the published amp specs are accurate, the Marantz is the one that needs a smidgen of attenuation
(roughly a dB). Frankly, you could try it without the attenuators... 1dB is pretty hard to hear and you
might actually prefer them that way.

I don't think I can add much more. Hope you're enjoying listening to them in whatever state they
end up in!

[tom1040]

Thanks to all! I now have a pretty good idea on what to do. Perhaps the 1500 Array sub could help the LF a tad (it already does, actually). If I do this I will post my findings. At the very least, perhaps it will put my mind at ease if it doesn't work out and I end up selling the McIntosh.

Again, thank you very much.