Biamping with Jolida/McCormack/Proceed

I thought I'd update this thread now that a few years have gone by and I've had a bit more experience biamping. I still have Legacy speakers and still use a Proceed AVP as my preamp and DAC. However, I have changed amps several times. I write this for those of you who, like me, must use one system for both your music listening desires and for movies.

For someone on a limited budget, I still find the Proceed a fantastic tool for both music and movies. It has a great DAC that can decode for two channel music, it also does Dolby Digital (or DTS) for movies, and it has a lot of options for configuring one's system, including biamping.

So, after trying a little Jolida on the top end of biamping, I tried a more powerful tube amp so I wouldn't have to biamp, but it never did handle bass the way I wanted. I then went the other way, trying to find a SS amp that had a tube sound. I wasn't happy with that either. IMHO no SS amp can do what a tube amp does best, and no tube amp can do what a SS amp does best. Thus, I was right back to considering biamping again.

I'd sold my McCormack DNA-1 some time ago, but I still have a McCormack 3 channel HT-1 (225 RMS @ 4 ohms), and I recently acquired a Cayin a-50T tube amp. I also have a 100 watt Parasound. So my plan was to use the Cayin for the mids/highs, let two of the McCormack's channels drive the Legacy's woofers (and the remaining channel handle the center channel as normal), and then use the Parasound for surrounds.

Another part of the plan is to use the Proceed's controls so I can adjust gain as necessary between the two main amps. I use the subwoofer out and one of the "auxiliary" channels which can be configured as L&R stereo subs; that way bass can be adjusted as necessary in relation to the less-powerful Cayin handling the mids/highs. Very cool also is that the Proceed allows you to choose the crossover point from between 70 and 120 hertz. Since my speakers' woofers cross over at 100hz, I set the crossover point there and thus using the Proceed is like having an electronic crossover without having to reconstruct the speakers. All that's left to do is set the Proceed to crossover for my main speakers.

I am really pleased with this set up. An added bonus is using the system to watch regular TV. Since most TV is center channel, and I leave the McCormack on all the time (and the Parasound too), I can watch TV without turning on the Cayin; it sounds great using just the center, subs, and the surrounds. And then when I listen to music, I turn on the Cayin and simply choose "no surround" on the Proceed for normal two channel music.

One last thing I've tried that works well. I use MIT Shotgun S1 cables throughout my system, but I couldn't afford another pair of speaker cables and ICs just for woofers. In the past I've noticed silver cables, done right, produce very tight bass. So I used Signal Cable's Silver Resolution for the woofer cables and ICs. I have switched between the Signal SRs and my MITs to test them, and I think the Signal SR cables produce equal or even slightly tighter bass, and (compared to MIT) at a bargain price.

Glad to hear it's working well for you, Ivan. I get the impression that your amps are at least similar (if not identical) which really helps. And most electronic crossovers give you level adjustment, which allows you to use amps with mismatched input sensitivity. Then there is the question of which crossover to use, what crossover points, what slopes, etc., etc.... Easy to see why it's a confusing topic!

SM

Wow, Steve, thank you so much for taking such extraordinary care in answering my questions. I certainly was not expecting such a coherent and detailed clarification. Many, many thanks.

I use an external crossover to bi-amp my own speakers. I chose to do so because I wanted to retain my relatively inefficient speakers -- I really like them -- while using low powered SET amps. I guess I got lucky. I am delighted with the result.

Regards,

Ivan

Hi Ivan -

You're right - it does get confusing. I think the problem stems from the fact that the term "bi-amping" is pretty generic, since all it means is using 2 amps, and there are quite a few options for how it can be done. In its original form, bi-amping (or tri-amping, etc.) involved the use of an electronic crossover to split the signal before the amplifiers, and the amps were connected directly to the drivers. More recently, speakers have begun to offer multiple inputs to the built-in crossovers to allow for bi-wiring, but this also opens the possibility of using multiple amps. This is still technically "bi-amping," even though no external, low-level electronic crossover is used. Both amps are driven full-range, and the speaker's own internal crossover does the job of shaping the signal sent to the drivers. There can still be a real advantage because multiple amplifiers can deliver more power with lower distortion, etc. However, you open a major can of worms at the same time if you use different amps, cable, etc.

I have experimented with various forms of bi-amping, and I can offer a few observations:

1) "Passive" bi-amping (which does not use an external crossover) can work very well if it is done with identical amplifiers and speaker cable. It *may* work well with different amps, but this is an extremely complex issue.

2) Passive bi-amping may be arranged either "vertically" or "horizontally." I believe the vertical arrangement works best, with one matched stereo amp per speaker and matching speaker cable. Each amplifier is driven with one channel's full-range signal, sent to both inputs (using a "Y" splitter across the inputs), and each output drives a separate section of the speaker. This means you are not only bi-amping, you are effectively running the amps as 2-channel mono, so you've got a bi-amped, bi-wired, dual-mono arrangement. The horizontal arrangement assigns one stereo amp to the high-end of *both* speakers, and another stereo amp to the low end of both. Each stereo amplifier receives the usual L-R full-range stereo feed from the preamp, but one amp is connected to only the high-pass section of both speakiers, and the other amp is connected to the low-pass sections. This will certainly work, but it defeats one of the main advantages of the vertical option: when both channels of a stereo amp are driven with the same signal, the amp is effectively used in mono, and there is no difference signal (or crosstalk) across the power supply and ground system.

3) In my experience, the main reason people choose to try any of these methods is because they think they can combine the best characteristics of *different* amplifiers (and often different cable) for improved overall performance. While this may seem like a reasonable idea, in practice it is extremely complicated and rarely works as well as simply driving the speaker full range with a single good amp. The reason is because speaker design has become very sophisticated, with the drivers, crossover, wiring, and cabinet tightly integrated into a seamless whole. Furthermore, many bi-wireable, full-range speakers have the low-to-mid/high crossover point somewhere in what is effectively the midrange, where our hearing is most sensitive. It doesn't take much change to upset the coherence of these designs. So, whether or not this sort of bi-amping works and, possibly, works well depends a lot on the speaker design and where its crossover points lie. I know a number of speaker designers who have chosen to sidestep the whole issue by eliminating bi-wire inputs. That way, it can't be screwed-up.

4) Using an external, electronic crossover does not necessarily help. Unless the speaker in question allows you to bypass its internal crossover and connect directly to the drivers, you are still using the internal crossover no matter what you do to the signal being fed to the speaker. Removing the "strap" or jumper connection across the bi-wire inputs does not bypass the internal crossover. Furthermore, if a speaker has been designed as an integrated whole including its crossover, an external electronic crossover would have to be designed to mimic the exact behavior of the internal crossover in order to achieve similar performance during bi-amping.

5) I like passive bi-amping a lot, especially the "vertical" arrangement, but I find it usually works best with matched stereo amps and cables.

As with all things audio, Your Mileage May Vary ;-)

Have fun!

Best regards,

Steve McCormack
www.SMcAudio.com

Steve,

I'm sure you are right. You are the expert, after all. But now I'm really confused. Is the method that you suggest considered bi-wiring or bi-amping? I bi-amp my own speakers with an external crossover, the links are removed at the binding posts, so each amp drives a particular set of frequencies discretely. What is the potential benefit of bi-amping without removing the speakers crossover from the picture? Is it the hope that there will be some magical synergy between two different sounding amps?

Regards,

Ivan

Thanks Ivan for your comment, I should have made it clear my speakers (Legacy Classic) are biwireable. Everything I've read says to biamp properly requires an active crossover and to disconnect my speakers' crossovers, but I don't want to go that far at this time.

Steve, I was pleasantly surprised to get a response from you, but grateful since I've not been able to find a specific answer to my question. I hesitate to try what I proposed because your amp already seems tube-like in the midrange and sweet on the highs. If someone weren't selling the Jolida locally and offering to let me try it out (and if I didn't have a little spare cash right now), I wouldn't do it. My biggest fear is that the tubes will cost me in high frequency extension and resolution, but of course now that you point it out, the loss of coherence too.

If I do try this I'll report back here. Thanks again for the advice.

With respect, Ivan, you are only partially correct. If the speakers in question have "bi-wire" inputs, then the high and low sections may be driven separately, and the speaker's own internal crossover will do the same job it always did (whether or not this is ideal is another matter). So it is possible to do just what Les3547 is proposing, and he can decide if the result is worth the effort. The input impedances do *not* have to match, assuming that the Proceed has a low enough output impedance to drive both amps in parallel (a safe bet in this case). In addition, the input sensitivities do not have to match *so long as* you have a way to control the level of the more sensitive amp. Again, this is the case with the amps that are being used. So, Les3547, go ahead and give it a try. You will need to adjust the level of your Jolida amp carefully with material you know well to get the high and low sections matched properly. This is critical, and it may take a few days to get it just right. It should be an interesting experiment at least, so have fun.

Finally, I will add one more thing: this sort of bi-amping is fun to experiment with, but it rarely works to complete satisfaction. A really good speaker design is a very subtle thing, and small changes in the behavior of the upper or lower sections can upset the coherence of the design. Different amplifiers (let alone different types of amps) sound different (surprise!) and introducing these differences across a crossover point often set somewhere in the midrange does not always work well. But you never know - that's why you've gotta try it!

Best regards,

Steve McCormack
www.SMcAudio.com

Hi,

To truly bi-amp you will have to defeat the speakers internal crossover. You need to use one amp for the mid-hi and one for the speakers low end. If you do it as you stated you will be sending the full range of frequency to the speakers low end, this will result in a very muddied midrange. You need an external crossover of some sort to direct the proper frequencies to each set of drivers.

Cheers,

Ivan