Biamping the RM40s

PLMONROE · « **on:** 5 Jun 2003, 03:03 am »

My RM40s have the toggle and dual binding posts. If I biamp what frequency range is handeled by each amplifier? Thanks.
Paul

shokunin · « **Reply #1 on:** 5 Jun 2003, 05:18 am »

I believe it's 166hz and up for the mid/treble and 166hz and below for the midbass/bass.

PLMONROE · « **Reply #2 on:** 5 Jun 2003, 04:51 pm »

So one amp drives the speakers below 166hz and the other those above 166hz? If I remember correctly, equal division of energy across the audio spectrum ocurrs at about 370hz. With division at 166hz I would need a more powerful amplifier for the top portion than for the bottom part. Is that correct? (I would have thought it the other way arround) Thanks.
Paul

John Casler · « **Reply #3 on:** 5 Jun 2003, 05:13 pm »

Quote

With division at 166hz I would need a more powerful amplifier for the top portion than for the bottom part. Is that correct?

Hi Paul,

The amount of power is dependant on the amount needed to created balanced SPLs.

Generally because it takes more power to energize the woofers, they require a larger wattage/amperage.

This is due to the fact that the woofers move substantially more air and themselves are much heavier (by thousands of times) than the moving diaphragm of a ribbon mid or tweeter.

shokunin · « **Reply #4 on:** 5 Jun 2003, 05:35 pm »

The balanced output is based on relative efficiency of the woofers vs. midpanels and tweeter. However, the crossover can also be designed to pad the output of the more efficient section to keep the output the same.

I am bi-wiring and the output seems about the same. IMO, the key to successful bi-amping is matching the input sensitivity of the two amplifiers. Some amps need only 1V to reach full output, others need more or less, which can cause differences in output which could be good or bad depending on how much power goes where.

JoshK · « **Reply #5 on:** 5 Jun 2003, 06:54 pm »

I'd really like to hear my RM40's with my Spectron on the bottom and a good linear tube amp on the top. Problem is with matching input sensitivity of a tube amp to a SS amp.

PLMONROE · « **Reply #6 on:** 5 Jun 2003, 07:38 pm »

I had the same difficulty of matching senitivities in a previous setup and ended up getting an Adcom Passive Preamp off e-bay which nicely solved the problem. Too bad I did not keep it. I am using a VTL 250 (Triode output) to presently drive my RM40s which has an imput sinsitivity of 132k. I would like to biamp using a Musical Fidelity A3cr for the bottom but it has an imput sinsitivity of 32K.

JoshK · « **Reply #7 on:** 5 Jun 2003, 07:57 pm »

Channel Islands VPC-1 passive volume control might be a good solution for around $300.