PDA

View Full Version : McIntosh & Marantz bi-amp JBL 1400 Arrays...



tom1040
02-07-2012, 09:55 AM
Would it be fairly simple to use a active crossover with Marantz MA9S2 mono blocks on the LF & McIntosh on the HF of the Arrays without having to mess with the speaker crossovers? If so, to the people who know of such things, what would I need.:dont-know:

Since I have this gear (Mac is idle at the moment), I would like to investigate the possibilities. The system sounds great as is but I am always curious.

Thanks!

Robh3606
02-07-2012, 10:20 AM
Yes and no. You need the active crossover to have the voltage drives Greg gave us and you would need to short one of the caps on the HF network board. You would also need to defeat the woofer crossover from inside the box. So it certainly can be done with a bit of work.

http://www.audioheritage.org/vbulletin/showthread.php?23763-Bi-amping-the-JBL-Model-1400-Array

Rob:)

Mr. Widget
02-07-2012, 11:07 AM
Yes and no. You need the active crossover to have the voltage drives Greg gave us and you would need to short one of the caps on the HF network board. You would also need to defeat the woofer crossover from inside the box. So it certainly can be done with a bit of work.

http://www.audioheritage.org/vbulletin/showthread.php?23763-Bi-amping-the-JBL-Model-1400-Array

Rob:)That is all true and is the "best" way to go about it, but you can passively bi-amp the system by disconnecting the loudspeakers' input terminal jumpers and using one amp on the woofer inputs and another amp on the HF inputs... to do this you will need two amps with identical gain or at least one with volume controls.


Widget

tom1040
02-07-2012, 03:19 PM
That is all true and is the "best" way to go about it, but you can passively bi-amp the system by disconnecting the loudspeakers' input terminal jumpers and using one amp on the woofer inputs and another amp on the HF inputs... to do this you will need two amps with identical gain or at least one with volume controls.


Widget

By chance, have you tried this? I cannot since I would be using different amps but, like I mentioned, I have them both-the McIntosh is just sitting around with nothing to do. I really don't want to have someone('cause I would be clueless) to mess around with the speakers just for a test.

Mr. Widget
02-07-2012, 05:14 PM
By chance, have you tried this? Nope... if I had the right pair of amps I might, but at present I am on a simplification quest.


Widget

jblnut
02-08-2012, 08:21 AM
You can do this right now without "messing' with the speakers". Just remove the jumpers between the HF and LF inputs on each speaker. Connect the LF input on each speaker to the same Marantz monoblock you are using now. Connect the HF on each speaker to the L and R outputs of the Mac amp. Then just make sure you have outputs from your preamp feeding both the Marantz and Mac amps.

Adjust levels to taste....

jblnut

PM me if you need any help...

Mr. Widget
02-08-2012, 08:29 AM
You can do this right now...See post# 3 ;)


Widget

jblnut
02-08-2012, 08:31 AM
Reinforcement - works for line arrays and forum posts too :)


jblnut

tom1040
02-08-2012, 09:42 AM
You can do this right now without "messing' with the speakers". Just remove the jumpers between the HF and LF inputs on each speaker. Connect the LF input on each speaker to the same Marantz monoblock you are using now. Connect the HF on each speaker to the L and R outputs of the Mac amp. Then just make sure you have outputs from your preamp feeding both the Marantz and Mac amps.

Adjust levels to taste....

jblnut

PM me if you need any help...


I think the problem lies in adjusting the levels. I can't.

jblnut
02-08-2012, 10:14 AM
You may not need to - I'd try it just for fun and see how it sounds.

Wait a minute, I did and I'm 3 amps down that road now :)


jblnut

Titanium Dome
02-08-2012, 11:19 AM
What's your pre?

tom1040
02-08-2012, 01:23 PM
What's your pre?

If your asking me, it is a Marantz SC7S2.

jblnut
02-08-2012, 01:25 PM
McIntosh C220 on my end...

Titanium Dome
02-08-2012, 02:32 PM
If your asking me, it is a Marantz SC7S2.

That's an attractive unit. As I recall, without looking it up, that has a bi-amp capability built in. Doesn't it also have gain control on each channel?

tom1040
02-09-2012, 04:05 AM
That's an attractive unit. As I recall, without looking it up, that has a bi-amp capability built in. Doesn't it also have gain control on each channel?

Perhaps it does on the remote. I will have to play around with that. Since the unit has few 'options' on first take, I didn't even look. I will give it a shot (although this a.m. I had an inquiry on the MC402 amp that IS for sale :)) Taken from the owners manual;


Floating control bus system

We make it possible to synchronously drive two or more controlamps by using a floating control bus system connected to asmany as 6 sets of control amplifiers. We also enable you totrim levels using the remote control, making it easy to set upthe optimal sound field on a multi-channel configuration. Thehighest achievable stereo performance can be accomplishedwhen a system configured with two sets of SC-7S2 and foursets of MA-9S2 are connected in a bi-amped mode.You will experience superb sound with unbelievable channel
separation.

I must say that the system as is sounds great to me. The Arrays are NOT asking for any more power. I was curious if this could be accomplised without too much hassle. I thank everyone who has contrributed to help me!

tom1040
05-22-2012, 07:21 AM
Since I now have some time to play around with this concept I have an additional question. The Marantz pre has two RCA pre-outs. Currently, I am using one for the Amps and one for the 1500 Array. Would it be possible to use a Y-splitter on one to both the Marantz and McIntosh amps and keep the one for the Sub? Don't they have to have the same impedance or am I way off base?

Please excuse my ignorance on this matter.

grumpy
05-22-2012, 08:39 AM
My minor concern is that you may be effectively doing this "Y" connection already.
Just because a unit has two pre-outs does not guarantee that they are isolated
(i.e., have separate line-level amplifiers for each connector, vs. just making the "Y"
connection inside the box).

You'd want to look at the input impedance vs. frequency for each unit you want to supply
a pre-out signal to. If the Marantz/McIntosh/1500 all have inputs rated at something like
20Kohms, you might now be loading it with ~7Kohms ... probably not a huge
problem electrically, but that 'rating' is a nominal and typically doesn't cover frequency
extremes. If they all dropped to 12Kohms on the high end, you would now be driving
about 4Kohms and the impedance variation from one end to the other of the audio frequency
range -might- cause a rolloff or exaggeration that would not be present with a single amp
connected.

Again, I don't think you'd hurt anything, but if you don't have facilities to measure,
you'll have to trust your ears.

tom1040
05-22-2012, 09:10 AM
Perhaps my post was not correct. As it currently stands, I am using one pre-out to the 1500 sub and one for the Marantz mono-blocks. I said 'amps' in my first post-perhaps, if I understand your response, I may have implied that I am using the Marantz/McIntosh already-which I am not.

I am sorry if I misunderstood. I do think the Marantz SC7S2 has two dedicated unbalanced RCA pre-outs and one balanced. You cannot use both at the same time, hence the reason I am using the unbalanced for the Amps(Marantz) and the sub. I am unclear whether I can, using a Y-splitter from one unbalanced pre-out, hook up two totally different power amps at the same time without some kind of issue. Conversely, Perhaps I could use one amp with a y-splitter with the sub & one or the other amp? Perhaps a active crossover would solve this issue?:blink:

Grumpy, I am sorry if you answered my question and I not smart enough to understand the answer. However, I thank you.

grumpy
05-22-2012, 12:29 PM
No problem, I've now looked up your particular preamp user manual.
That is one unusual preamp :)... but the gist of what I was attempting
to convey remains. The SC7S2 has a 70ohm output impedance ... it's good
that it's low. It will probably drive 3 normal amp-input loads without issue
(unless you use really high capacitance cables). Generally going past -two- line
level splits is a poor idea for a blind recommendation... hence my initial caution.

If you look at the block diagram in the User Manual (pg20) you can see
that it is showing 1/2 of the preamp signal chain (ch A). Also, the RCA
output jacks are internally wired as a Y-connection. Adding an external Y
adapter will mean you are then driving three loads in parallel
from one pre-out line amp (regardless of the number of pre-out connectors).

When using the RCA pre-outs you are leaving the top section of a
balanced design out (the negative half, connected to pin 2 of the XLR)...
which explains why they want you to use XLR -or- RCA, not both...
you would be unbalancing the circuit (loading one leg more than the other)
and losing much of the benefit of using a balanced connection.

The bi-amp function of this pre requires a full passive filter (the same signal drives both
the LF and MF/HF amps... it is the speakers filter that provides the crossover)
so signal-wise, the multi-way split to amps and subs (with it's own crossover)
is fine. If you want the full-range speakers to not run full range, and the crossover
in the sub to define the low end of those speakers, you'd send the pre-out
to the sub, then the high-passed output to the amp for the full-range speaker
(using the sub's electronics as an active filter).

As you can see, there are many connection options and the user manual is just a
start. Hope this helps some :dont-know:

timc
05-23-2012, 12:12 AM
You cannot use both at the same time, hence the reason I am using the unbalanced for the Amps(Marantz) and the sub.

Are you sure about this? A friend of mine has the SC7 and he uses the balanced set for the MA-9's and a unbalanced set for another amplifier. He then dials the MA'9s to -6db on the input.

-Tim

tom1040
05-23-2012, 06:14 AM
Are you sure about this? A friend of mine has the SC7 and he uses the balanced set for the MA-9's and a unbalanced set for another amplifier. He then dials the MA'9s to -6db on the input.

-Tim

Interesting. I will review the manual again. First, a question: Does he use them @ the same time? You can hook them up, I think, but use the switch on the front of the Marantz Ma9S2 amps to switch from unbalanced to balanced. Perhaps he uses them that way. Nonetheless I will check. Thanks guys.

So, an active crossover is of no use to correct this?

grumpy
05-23-2012, 02:28 PM
All I got from the manual is that it wasn't recommended, not that it wouldn't 'work'.
An external crossover could work fine, ... Getting it done properly would be the challenge.
Passive bi-amp seems like a good start if you can level match your amps.
RCA attenuators exist (don't have to build anything).

Mr. Widget
05-23-2012, 04:41 PM
Passive bi-amp seems like a good start if you can level match your amps.
RCA attenuators exist (don't have to build anything).By RCA attenuators, do you mean line level passive volume controls? If so, those can be very impedance sensitive. (For those confused by this, the impedance of the amp/preamp, not the speakers.)


Widget

grumpy
05-23-2012, 07:04 PM
Sure. I figured there would be some empirical level adjusting going on, vs trying to hit an exact value. If we had all the numbers (gains and impedances), and some construction was OK, we could get pretty close.

timc
05-23-2012, 11:59 PM
Interesting. I will review the manual again. First, a question: Does he use them @ the same time? You can hook them up, I think, but use the switch on the front of the Marantz Ma9S2 amps to switch from unbalanced to balanced. Perhaps he uses them that way. Nonetheless I will check. Thanks guys.

So, an active crossover is of no use to correct this?


He uses them at the same time, with passive biamping. BUT this is the S1 model. Maybe they changed it for the S2?

tom1040
05-24-2012, 06:31 AM
He uses them at the same time, with passive biamping. BUT this is the S1 model. Maybe they changed it for the S2?


It appears the 'instructions' of both the S1 and S2 seem to indicate that it should not be done. I am a bit curious why your friend does it that way-in other words, not just to use the unbalanced RCA connectors-unless one is for a sub, such as the case with my situation-or perhaps the benefits provided by the balanced connections. I may be reading the instructions wrong.:confused:


I suspect that I just need lug the McIntosh (no easy task!) out of storage and try some configuations or just forget about it and leave well enough alone.

grumpy
05-24-2012, 07:38 AM
The gain difference between the MC402 (using the 8 ohm autoformer tap) and the Marantz MA-9S1/2 is
about 0.6dB (unbalanced inputs) if the specs are listed correctly.

If the attenuator on the back of the Marantz is continuous (not stepped), this would be the
simplest place to adjust levels.

Another "simple" option would be to insert a 1.4Kohm resistor in series with the Marantz
(essentially a very custom, but easy to make cable). With the 20K input impedance of
the Marantz, that would drop the sensitivity ~0.6dB.

So much for morning bench racing... this would be much better done by someone who can verify
measurements in-situ.

timc
05-25-2012, 06:53 AM
It appears the 'instructions' of both the S1 and S2 seem to indicate that it should not be done. I am a bit curious why your friend does it that way-in other words, not just to use the unbalanced RCA connectors-unless one is for a sub, such as the case with my situation-or perhaps the benefits provided by the balanced connections. I may be reading the instructions wrong.:confused:


I suspect that I just need lug the McIntosh (no easy task!) out of storage and try some configuations or just forget about it and leave well enough alone.

He (me too) feels that it sounds best when the mid/treble is run balanced. Might got to do with the lower noise.

tom1040
05-26-2012, 10:55 AM
Well, perhaps this was not meant to happen. I have a strong feeling that I have the McIntosh sold. I guess I will know by next week. At least I will not need to ship it!:eek:

tom1040
05-29-2012, 07:43 AM
The gain difference between the MC402 (using the 8 ohm autoformer tap) and the Marantz MA-9S1/2 is
about 0.6dB (unbalanced inputs) if the specs are listed correctly.

If the attenuator on the back of the Marantz is continuous (not stepped), this would be the
simplest place to adjust levels.

Another "simple" option would be to insert a 1.4Kohm resistor in series with the Marantz
(essentially a very custom, but easy to make cable). With the 20K input impedance of
the Marantz, that would drop the sensitivity ~0.6dB.

So much for morning bench racing... this would be much better done by someone who can verify
measurements in-situ.


Pardon my ignorance but are you speaking of something like this?




http://www.ebay.com/itm/10-NEW-RCA-Male-to-Female-0-5dB-Attenuator-Gold-plated-/360234133875?pt=LH_DefaultDomain_0&hash=item53dfa0

tom1040
05-29-2012, 10:45 AM
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
05-29-2012, 11:03 AM
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
05-29-2012, 11:13 AM
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
05-29-2012, 11:20 AM
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
05-29-2012, 11:30 AM
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
05-29-2012, 12:28 PM
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
05-29-2012, 12:44 PM
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
05-29-2012, 12:47 PM
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
06-05-2012, 01:24 PM
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
06-05-2012, 02:06 PM
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
06-05-2012, 04:14 PM
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
06-06-2012, 07:42 AM
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
06-07-2012, 05:32 AM
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.:D