What does more power do for Magnepans?

Hi Jim, you said : Playing tracks of Allison Krauss (acoustic ensemble) and Dandy Warhols (bass heavy psychedelic) with fairly narrow dynamic ranges at levels I occasionally listen at… 93-95db peaks measured @ 11 feet (observed) produced these peak voltage readings (observed);

A. Krauss track
HF ~ 1.8 – 1.9 V
LF ~ 3.9 – 4.1 V

D. Warhols track
HF ~ 1.8 – 1.9 V
LF ~ 4.2 – 4.3 V

I was wondering if you adjusted/changed the volume levels for the two different songs when you obtained these measurements?

Bob

Bob,

I set the volume pot at a level that I occasionally listen to and left it there. I was more interested in measuring at a known volume level to see how much juice the speakers were pulling.

They are both "modern" recordings (CD) and fairly close in "average" level. The D Warhols just has a ton more bass energy. So the peak SPL for that recording were probably higher.

If there is something specific your wondering about, I can rerun the little experiment and equalize volumes as best I can. Watching the little bar graph jump on a RS meter is not the most precise thing in the world. Nor is watching a fluctuating multi-meter. I also have some analysis software, but I don't know if it will measure a lengthy enough sample to find the peaks.

I have to learn to be careful in my statements here, too many sticklers for precision. This was just meant as an interesting observation, not accurate science.

Jim S.

Stilljd...It appears that your voltmeter was the analog kind. Reading this when the signal is fluctuating would be difficult. My meter is digital. It makes a measurement about once a second. All I have to do is remember the highest value that I see over some reasonable test time.
For some things, digital is best!!

If you want something more to do, try making some measurement of the total amp output: not HF and LF separately.

El,

No, it is a digital multi-meter. Just slow to react. Less than $10 at RS.

To do total amp output I would have to undo the active biamp setup and reinstall the passive crossovers in the 1.6's. And get better measuring equipment! Your early results and postings gave me enough motivation to check the seperate panels driven by seperate amps. It was mostly just general curiosity.

But, I got a lot out of the little experiment. Learned a small fraction of electronics theory, its pratical application, and why there is so much potential in a vertical biamp setup with the Arcam/1.6 combo. Clearly, dividing the 2x+ current draw of the low frequency panels between the power supplies of a pair of 2 channel amps instead of using a single 2 channel amp and its power supply for the low frequencies has a great benefit potential. I think there is the potential for added IM distortion when running HF and LF through the same transformer in a vertical setup. We will see if I can hear it.

Here in Cincinnati, we are rained in today. Guess what I am going to do today. Go Vertical!

Then I got to quit fussing around with electronics and make some room treatments!

Jim S.

Jim, I am unfamiliar with Maggies and I did not quite follow your measurement scenario so maybe I am missing something. But I did learn a lesson the hard way on my speakers. Adding a second amplifier (identical to the first) did not double the available power. I did gain the benefits of going to an active crossover vs a passive crossover but the small power gain was pretty much the result of the crossover type change, not the extra horsepower up front. And maybe there was no power gain at all and it was just the change in presentation from the crossover change. Anyway, the failure to increase power was a major surprise and disappointment but an excellent learning experience.

Consider this for a two-way speaker (considering one channel at a time). One amplifier sees the combined impedance of two drivers in parallel. That combined impedance is less than the impedance of the highest impedance driver. The amplifier will have a certain output into that impedance.

Add a second amplifier identical to the first. Each amplifier channel will see the impedance of a single driver. That impedance will be higher than two drivers in parallel and the amplifier output will be diminished.

If I got this wrong I would appreciate a gentle education. Those few members who continually post negative and critical comments need not respond.