2. amps-preamps
  3. 1185660642

Biamping with Jolida/McCormack/Proceed

Hi All,

I've read many of the threads on biamping here. I apologize for asking what I’m sure is covered somewhere, but I ask because I couldn’t find enough specific information to reassure me. I did read enough to know what I want to do is less than ideal, but it’s all I can afford right now.

I have a chance to try out a Jolida 102b integrated amp (before buying it) biamped with my McCormack DNA-1 power amp. I would control them with my Proceed AVR preamp (using its DAC).

The Proceed has “remote” analog output RCA output*, plus a switch where I can let my Proceed’s volume control adjust both the main and the remote output simultaneously. The Jolida of course has its own volume control and analog inputs. (*The Proceed has main/remote xlr output too, but neither amp has balanced input.)

I’ve read various things including that if I set the volume control on the Jolida and leave it alone, it will work fine. But I have also read that the amps’ input impedance should match, and in another place that their input sensitivity should match. In neither case do they appear to precisely match:

Jolida 102b:
Input Impedance: = or < 250Kohms
Input Sensitivity: Max. 900mV for 20 watt output at 1KHz

McCormack DNA-1:
Input impedance: 100k ohms.
Input sensitivity: 1.2V.

I want to ask if I should try this, and if so how I should hook it up? My idea as of now is to use the Proceed’s remote output to drive the McCormack hooked to the low side of my speakers; and to use the main outputs to hook to the Jolida, and then to the mid/high side of my speakers.

If I need any sort of attenuation or gain adjustments besides what I can do with the Jolida, would you please suggest? And if the Jodida can be adjusted, how? Remember, I just want to try this out without investing much beyond the Jolida.

Thanks in advance for any suggestions you may have.
les3547
iramirez
68 posts
 
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
stevemcx
166 posts
 
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
les3547 OP
22 posts
 
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.
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