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Biamping Mac Tubes and SS

S

syaudio

New Member
Dear Mac lovers,:music:

Have a quick question, would love to get your ideas.
I will have B&W Nautilus "the shell" in a week and thinking about using all Mac amps. This baby requires 8 separate channels of amps (4 each)

I am thinking about MC1000s and MC501's for the bottom two, and MC2000 and MC275 for the top two (HF/MF).

The only issue is the gain matching/controlling of these amps. I think MC1000/501 are OK but not sure the MC2000 & 275 (vs SS amps) since they are tubes. If they are out of sync and I cannot seem to locate any gain control knobs in these, what are my other options? (if any...)

Has any one dealt wth biamping these SS/Tubes? Appreciate your help
 
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First welcome to AK!

Next, I have done it & you balance them using the output taps.

You will have a very nice compliment of Power!
 
Thanks Masterlu.

My dilemma is that this will get you to the near appoximity of balance but will not get there accurately. Without being too "scientific" and without using a techy equip. is there a rule of thumb on this for the Mac? I am interested in the "experience" of those who actually used tube power with SS. I listen to Jazz a lot.
 
syaudio said:
Thanks Masterlu.

My dilemma is that this will get you to the near appoximity of balance but will not get there accurately. Without being too "scientific" and without using a techy equip. is there a rule of thumb on this for the Mac? I am interested in the "experience" of those who actually used tube power with SS. I listen to Jazz a lot.
Click to expand...


Me too, tube amps on top (tweeters) or (mids & tweets) with SS on the Bass will yield some outstanding results!

Wait till I snag some MC2301's...
 
Welcome Syaudio :)

The easy answer is to just get 8 MC501s and forget about it.

I have never heard the Nautilus speakers but with an active crossover the amps will be much more efficient and the MC1000 may be overkill, the newer design of the MC501s may sound better for the bass. I would even think that 4 MC275s would be able to produce some very loud music with these speakers. How big is your room and how loud do you listen?

What amps do you have right now and what preamp are you going to use? Your best bet is to demo the amps, I have not heard anyone here talk about these speakers but I'm sure we would all love to hear them. I think you are going to have a lot of fun getting this system setup, make sure and let us know how it works out.

Victor
 
Victor said:
Welcome Syaudio :)

The easy answer is to just get 8 MC501s and forget about it.

I have never heard the Nautilus speakers but with an active crossover the amps will be much more efficient and the MC1000 may be overkill, the newer design of the MC501s may sound better for the bass. I would even think that 4 MC275s would be able to produce some very loud music with these speakers. How big is your room and how loud do you listen?

What amps do you have right now and what preamp are you going to use? Your best bet is to demo the amps, I have not heard anyone here talk about these speakers but I'm sure we would all love to hear them. I think you are going to have a lot of fun getting this system setup, make sure and let us know how it works out.

Victor
Click to expand...

I agree with Victor...gain matching in an active multi-amp setup is a b*tch.
A stack of 501's will do the trick and compensate for the analytical character of the Nautilus Shell. Just imagine, the sight alone of 8 501's will look spectacular.
From the B&W website: "amplifiers of 100 watts upwards are recommended, with 500 watts being the optimum for the low frequency drive unit"
BTW... doesn't the active crossover supplied with the B&W Nautilus Shell allow for gain-matching for each of the frequency bands...you will need a scope or sensitive dB meter though.

and please don't forget

:worthless
 
All Mac lovers,

thanks for all your advises. I will have the pictures soon. Unfortunately, I can't afford 8 501's yet, but will get there sooner or later. In the meantime, as Masterlu suggested, I am going to play with the tube and SS combo.
 
Gain matching of muti-amps

Dear Mac lovers.

I finally gave up after 2 weeks of trying to match these amps with B&W Nautilus "shell". I have a pair of MC1000s, MC501s, and 2 MC2000s, but I can't seem to have all working in one direction.

Crossovers B&W supplied are without gain volume control. I am leaning towards buying a crossover unit. Q for the community.

What 4 way channel divider in the marketplace today do you recommend? (w/gain voulme control)

I must say the speakers are a quite of dissapointment for me ($60,000 dissapointment + cost of amps)
 
syaudio said:
Dear Mac lovers.

I finally gave up after 2 weeks of trying to match these amps with B&W Nautilus "shell". I have a pair of MC1000s, MC501s, and 2 MC2000s, but I can't seem to have all working in one direction.

Crossovers B&W supplied are without gain volume control. I am leaning towards buying a crossover unit. Q for the community.

What 4 way channel divider in the marketplace today do you recommend? (w/gain voulme control)

I must say the speakers are a quite of dissapointment for me ($60,000 dissapointment + cost of amps)
Click to expand...

I am sorry to hear it :sigh:

"Gain matching" is underestimated when it comes to active bi amping with external crossovers.

You could try the crossover offered by PassLabs (you would need two units)

http://www.passlabs.com/downloads/xvr1_lit.pdf

http://www.passlabs.com/downloads/xvr1_om.pdf

(I have no idea how this one would perform with the B&W)...your best bet, if you decide to keep the Nautilus is to make all amps the same type.

Third alternative is the go shop at the Pro-Audio brands.
 
Jem666 said:
I agree with Victor...gain matching in an active multi-amp setup is a b*tch.
Click to expand...

I'm not sure that I agree... then again, perhaps I'm missing something here as part of the equation.

I am actively biamping (2 way) using an Electrovoice Dx-38 for my active. I can plug ANY amp I want to in it and quite easily match amps (which I presume we mean input sensativity?)

use the forumla "20*Log(V1/V2)" where V1 & V2 are the input sensativities. In order to not confuse...if you put the higher value on top, you won't get a negative number and cause confusion.

Example, my MC-2102 has an input sensativity of 5 when using balanced inputs and the Crown K2 I have has a 1.4 input sensativity.

So, 20*Log(5/1.4) = 11.0568 On my active crossover, I need to attenuate the more sensative amp (Crown @ 1.4V) by 11 db's and they will be in synch.


hmm... I just thought of something that might be why a 3 way is more difficult... this equation only accounts for 2 amps :scratch2:. Still...it can't be rocket science.

Well... I know...I'll send a flag to someone and see how he does 3 ways because I KNOW he does 3 ways also.

For you mathematical type... could it be as easy as just doing the above twice using one amp as a reference point?? (seems kinda reasonable to my pea brain)
 
I've not heard back but I think it makes sense to me... if you have 3 way speaker (and therefore 3 amps with different input sensativities)

I don't see why it wouldn't work to do the equation twice, meaning

Example, amps have 5, 3 and 1 volt input sensativities. Pick the most sensative (1v) and then

20*log(5/1)= 13.9794
20*log(3/1)= 9.5424

Which would tell me that you don't touch the 5v amp but the 1v amp gets attenuated 14 db's and I guess you'd have to increase the signal level to the 3v amp by 9.5 db's to bring it into line with the 1v (since you can only reduce it relative to one of the amps)

Mind you, this is my own logic...not heard back yet from Roy.

Thoughts? (other than it would be much easier to get 2 matched amps!!)
 
change that... I think I just realized error of logic.

Instead of using the highest volt amp as reference, I think you'd use the lowest

So

20*log(5/1)=13.9794 (or 14 db's)
20*log(5/3)=4.437

So you would take the 1v input sensativity amp and reduce it 14 db's to match the 5 volt amp and then you'd take the 3 volt amp and reduce it 4 or 5 db's to also match it to the 5 volt amp.

(on my unit I can only increase/decrease in whole db's as I recall not 4.4)

anyway... that is how I'd approach balancing different amps for same output
 
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