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Bi-Amping

Hi everyone,

Well I steped up to dual power amps and bi-amping my custom made (self built) speaker system that I have finally finished- Cerwin Vega 15 inch subs, Vifa 8" bass and 6.5 Mid bass, dual Vifa 3 inch SoftDome mids, with a Morel 30's for the tweeter. The subs are @ 80Hz (via the B&K), the speakers are crossed @ 300Hz, 500Hz, 700Hz, and 3200Hz- 2nd order for the lows and 3rd order for the highs. One amp runs the subs and the other the speakers.

I am using two (2) Proton D-1200's, a B&K PT5 preamp, with an Audio refinement CD player. I am running Monster MCX 2s wire (4- 15' foot runs), Audio Quest power cables, and Monster M850i Interconnects, this is connected to a dedicated 20A wall outlet.

My room size is 28x14, shot gun style, painted dry wall, and half carpeted/harwood flooring, 8' room height.

My question is: I was expecting a more powerful sound then what I have presently. While everything did open up, it seems the DB output did not increase substantially, as a matter of fact, it seems I must now nearly max the volume control on the B&K to achive similar output when I was using a single amplifer. All be it, the sound is more refined and much tighter, the DB output did not increase. And I am concerned that the B&K is having trouble outputing enough voltage to run two amplifiers.

Is this the norm? Am I not suppling enough "juice" to the amplifiers via the wall outlet? Or, do I have to large a "hole" between the subs and the Speakers?

While this does sound very impressive, I am not as "jazzed" as I thought I would be.

Any ideas, comments, help?
alpha_03
alpha_03 OP
39 posts
 
Oh and BTW, (sorry I missed this comment) here are the specs according to the Proton manual:

Rated power output 20Hz to 20khz 110 wpc

Dynamic Power at 8 Ohms/4 Ohms/2 Ohms

20ms - 540/1000/1500 wpc

Dynamic Headroom @ 8 Ohms/4 Ohms/2 Ohms: 7.3dB

I.M.D @ rated power: 0.02%

Damping Factor: 150

Freq. Responce 20-20kHz: +/-.02dB

Power Bandwidth @T.H.D 0.1%: 10 - 40kHz

Input resistance / capacitance: 1V

Channel Crosstalk: 85dB

S/N ratio 120dB

Hope this helps (I guess)
ar_t
165 posts
 
This one makes no sense:

"Input resistance / capacitance: 1V"

Check that one, and let us know...........

The one about "dynamic power" is just marketing nonsense, written to impress you. The idea is that the peak power, at the top of the waveform, is calculated to be such-and-such watts. In the real world, it is a useless figure.

The one about head room is more revealing. That tells me it probably has a smallish power supply, and that the rail voltage will sag a great deal under a constant load. Problem is, they give one figure for all 3 impedance levels, and that can't be right. I bet it is a lot less than 7 dB @ 8 ohms. At least I would hope so.

So much for believing specs.
alpha_03 OP
39 posts
 
No offence Ar t, but you obviously have no experience with Proton gear. And yes those specs I posted are correct, as taken directly from the Proton manual. In their day the Protons were among the most powerful amplifiers money could buy, and even today they still make one of the best tube televisions on the planet. And no it is not a marketing play, ploy or other. They use twin transformers and are of a dual mono design, with over 60,000mfd of capacitence.

However, FYI, I have at my disposal several amplifiers, ranging from Rotel, AB International, Crown, Carver, Sumo, and Adcom. One single Proton is more powerful then all of them, some which are rated to 500 wpc, real world power.

Perhaps it is your belief that I am some how stupid, uninformed, or ignorant as to the workings of electronics, and specs as they go? I surely hope you do not think this to be the case, for if you do, you would be very mistaken.

BTW, since when is 7.3dB of headroom indicitive of a "smallish" PSU? These amps weigh 36.5 lbs each, as per my digital scale, not light, but certainly not Krell's either.

If you get the chance, audition one, you'll be impressed, when one considers their design, age, asthtics and cost. Even today - on ebay they bring $300.00- to $500.00, those who know what they are snatch them up as fast as they are posted for sale.

BTW, ever heard of Onix? Legacy Audio of Ohio? NAD?
alpha_03 OP
39 posts
 
opps, I left out your initial question, I did actually miss a line, the above question you asked:

It should read:

Input sensitivity: 1V

Input resistance / capacitance: 15k OHM / 220pF

sorry for the mistake
ar_t
165 posts
 
That sounds better. Any preamp should be able to drive 2 of those (or most anything) in parallel.

As for specs.........

Most are not to be taken seriously. Does not matter who wrote them, or for what gear. I'm sure you told us what they claim the specs are. Doesn't mean they are correct.

Back to headroom..........

If that figure is for 8 ohms, then the supply is too small. If it is for 2 ohms, then probably not. But they don't really say, do they? In which case, it is a meaningless number.
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