Re: M80v2 with NAD bridged amps
|
Joined: Apr 2008
Posts: 40
buff
|
OP
buff
Joined: Apr 2008
Posts: 40 |
John,
Thanks for your detailed input. Maybe you can help me understand where my thinking is off; my understanding is:
A bridge tied load (BTL) amplifier applies a normal signal to one terminal of the speaker, and an inverted signal to the other. If a single channel of the amp is capable of producing 20V RMS across the terminals of the M80, this equates to P = V2 / R, so in this case, 20^2 / 4 = 100W.
When connected in BTL, the M80 "sees" 20V at one terminal, and an inverted 20V signal on the other - a total of 40V RMS Using the same formula, 40^2 / 4 = 400W - four times the power. But, each channel of the amp now sees only half the load impedance (think of an imaginary center tap in the voice coil, connected to ground). The amplifier must be stable into 2 ohms, or bad things happen..
regards, clay
|
|
|
Re: M80v2 with NAD bridged amps
|
Joined: Sep 2002
Posts: 1,488
connoisseur
|
connoisseur
Joined: Sep 2002
Posts: 1,488 |
Haoleb, Thanks, that's a great point. I guess that an external crossover before the amps would be ideal in this case, but is actually not needed, I could remove the bi-jumpers and send the full spectrum signal to each set of drivers, and the let the internal networks do the work. Great tip!
I'm a big believer in the having power reserves to accurately deliver transients; its what makes music 'real' to me.. Yes, I forgot to mention that in this type of setup you must remove the gold strap jumpers on the speaker terminals. Or else you would probably be shopping for new amps. There is no need for an external crossover. Its essentially the same as the bridged configuration only... different. When I had the NAD I never thought that the amp seemed strained while driving the M80's at loud levels but once I had gotten my monoblocks (also Odyssey's) It was clear that it sounded stressed on certain passages where the mono's didnt at all, So I definetly know what you mean about having the extra power.
|
|
|
Re: M80v2 with NAD bridged amps
|
Joined: Apr 2008
Posts: 40
buff
|
OP
buff
Joined: Apr 2008
Posts: 40 |
Brandon, I will not forget the straps! ;^)
I ran my C370 solo before I got the C270, and at elevated listening levels you can hear the C370 strain to keep up. One of my favorite Electronica CDs is Faithless's Outrospective; adding the C270 to the mix gave the music the 'slam' that you hear when you see them live.
Very nice web site, btw.
clay
|
|
|
Re: M80v2 with NAD bridged amps
|
Joined: May 2002
Posts: 10,654
shareholder in the making
|
shareholder in the making
Joined: May 2002
Posts: 10,654 |
Clay, the point is just that the speaker(including its impedance, since nothing analogous to that imaginary center tap is happening)doesn't change; it's the amplifier that changes. Of course if the added maximum power capability present when bridging is actually used(unlikely), then more current is necessary for the increased power, but it's because of the increased voltage from the amplifier, not any decrease in effective "seen" impedance in the speaker. If the use of the "sees" terminology is necessary(shouldn't be), then maybe it should be said that the speaker sees twice the voltage.
-----------------------------------
Enjoy the music, not the equipment.
|
|
|
Re: M80v2 with NAD bridged amps
|
Joined: Apr 2008
Posts: 40
buff
|
OP
buff
Joined: Apr 2008
Posts: 40 |
If the use of the "sees" terminology is necessary(shouldn't be), then maybe it should be said that the speaker sees twice the voltage. I agree with you here! You're right, the issue with speaker impedance is ALWAY about the ability of the AMP to deliver the voltage.
|
|
|
Forums16
Topics24,945
Posts442,484
Members15,617
|
Most Online2,082 Jan 22nd, 2020
|
|
0 members (),
705
guests, and
3
robots. |
Key:
Admin,
Global Mod,
Mod
|
|
|
|