Contac Linn and ask em! I've talked to a tech a time or two in the past, calling from the US!
19 responses Add your response
Possibly but you may encounter the unbalance if they do not have the same gain. One will outdo the other and throw the sound off. You may need a crossover which will allow adjustments to gain in each amp and some to different frequency adjustments. Bryston makes great crossovers for this very thing.
You must match the output levels for the amps first otherwise the top or bottom will not sound balanced. Second is to get an active cross-over to be able to adjust the sound. I posted about this a few weeks back but have decided to stick with one amp for now. Too complicated with cables, power cords, room for all this stuff for the amount of time I am listening to music recently. If you can put in the time and expense, this is the way to go.
This is what is known as "Fool's Bi-amping"!! It's bi-amping for the sake of bi-amping. While it is true that you might reap some benefits, the hassles of making sure that high & low are matched is perhaps not worth the time & additional expenditure of cables.
It would be much better to get a very good external xover ckt. This will keep the low freq. out of the high freq path & ensure that the high freq amp is only responding to the signal it really should. This will also keep the speaker cones from mistakenly responding to the low freq. signal, which could cause smearing. Similar argument holds for the low freq amp & the woofer driver.
If you have a volume control on the McIntosh that will help a lot but the tone of the ss & tube amps might be very different. Thus, even if the ss amp gives better bass control you might not like the tone diff.
Just MO, ymmv. fwiw.
I am biamping, with great success, my MG3.5 with ARC VT100 MKII (tube) on the treble/midrange and Kenwood L07M (SS) on the bass panels.
I am using the Marchand 126s active crossover. For proper blending I am using 250 Hz @6dB/Octave for the high pass and the low pass at 200 Hz @ 18dB/octave.
It is incredible how people on this forum can make such sweeping, and incorrect generalizations without clarification.
If you ask Linn they will stand for product against removing built-in crossover and they're partially right. On the other hand passive bi-amplification of even perfectly matched amps can drive system out of tonal balance. Volume control in your Mac might help matching but will not help to keep balance due to the complexity of a speaker load connected to two amplifiers.
Without worries you can do it with electronic crossover $500...$1000.
I suppose that "Gmorris" is pointing to my post with his 'It is incredible how people on this forum can make such sweeping, and incorrect generalizations without clarification.' statement!!!
However, it should be noted that "Gmorris" has done EXACTLY what I have written to achieve successful bi-amping namely using a good/excellent active xover!
The only doubtful thing I mentioned in my post was blending the tone of the ss & tube amps & "Gmorris" has a PARTICULAR solution that fits HIS needs. This is perfectly fine. It is also the reason that I did not recomend either 6dB/oct or 12db/oct etc slopes or xover frequencies 'cuz each system is different. What works for "Gmorris" might not work for "Kcw001".
It appears that my statements were not so "sweeping, and incorrect generalizations" after all!!
IFFFFF "Gmorris" has achieved successful (sound-wise) bi-amping WITHOUT active xovers, then I would have made "sweeping, and incorrect generalizations".
"Gmorris" can correct me if I'm wrong in saying that "Kcw001" would be wasting his time bi-amping WITHOUT an active xover.
Just my feedback. FWIW.
You would like to use tubes on top to enjoy the lush, liquid sound. However, you also want the low end slam of SS. Passive bi-amping (some may call it "Fool's Bi-amping" does not have all the advantages of active bi-amping. However, in your case, a key advantage is obtained. Despite presenting full-signals at the input to both tube and SS amps, you will definitely reduce the load burden experienced by the tube amplifier. It will not "see" nearly as much of the speaker's low end load. This is where the majority of current and power are consumed. Therefore, your output tubes can run somewhat cooler and you will not drive your tube amp towards clipping as quickly at high volume.
One tweak that will help this configuration further is the addition of a High-pass filter to the tube amplifier's input. This can be nothing more than a capacitor soldered behind the input socket. The size of the cap is chosen according to the cut-off frequency you desire. Now the tube amp does not have to internally deal with the low end spectrum, thereby enhancing performance further. You have now reduced smearing and other harmonic distortion effects.
Active bi-amping not only requires an active cross-over feeding the independent amplifiers, it also requires a viable means of bi-passing your speaker's embedded x-over.
First you must know the cross-over frequency of your speaker (low end). On my Martin Logan SL3's, it is 250 Hz. Therefore, I would choose something less than this to make sure I preserve the integrity of the internal x-over circuit inside the speaker. So in my case, I could choose 180 Hz. You want a simple, single-pole low pass filter. Therefore, a single capacitor will suffice. You also need a resistor if the input port is not already using one. The capacitance is determined according the relationship between cutoff frequency, resistance and capacitance. You'll need to dig out your EE book or use a tech for your case. The cap will likely be something < 1 uF.
A key point is that this is a purely passive filter, below the x-over frequency. Therefore, there is no degradation to the signal whatsoever. Cap quality is less of an issue, use something "reasonable".
Your suggestions seem to be fine but you're still facing a "double-degradation" using passive crossovers on two sides amplifier and speaker-embedded.
A capacitor tended to bring more distortions than any active element so mainly a lot of engineers try to avoid their introduction unless for smoothing in PS or forward or reverse correction of RF in input and feedback circuitries. A further note that capacitor isn't an ideal and "strong" filter as you may expect and more or less will pass portions of "unwanted" amplitudes in such interaction.
The more complicated part that is not probably covered in EE books due to complexity of calculations and tremendous time to be spent for testing is integrating built-in speaker crossover or actually complexed speaker load with built-in crossover with filters tended to be used on amplifier side.
In the context of cross-overs and bi- (or tri-) amplification, the word active simply refers to the fact that no energy from any one amplifier is used on more than one target driver. While this is a good thing (listen to a Meridian active speaker system for verification), it is still achieved via filtering. That is, the active cross over, which acts on the line level signal, uses capacitive components to filter the signal and thereby introduce its own contribution to "signal degradation" and distortion (however minimal).
My suggestion above on the HP filter is a means of reducing the energy outside the pass-band of the speaker's x-over circuit. I stand by the concept that the consequent performance improvement should outweigh any effect that an RC combination will have on signal frequency components above the corresponding x-over's cutoff frequency.
Notwithstanding this, I concur w/ Gmorris that using quality caps and resistors is prudent, at the very least. At the same time, man-o-man I wish this would all be easier... ;-)