Adcom GFA-545 II bridging question

dhoover · 29th August 2006, 03:55 PM

Is there any way to bridge this amp for mono use? I've searched the web and emailed Adcom. Response from Adcom is that there is no way (not surprised). I don't feel like retiring this amp entirely. Thanks

djk · 30th August 2006, 01:55 AM

It's a lot of work, and would only drive an 8 ohm minimum load. I wouldn't do it.

anatech · 30th August 2006, 02:29 AM

Hi dhoover,
Why would you do this for about +3dB? If you consider driving a pair of subs, one from each channel, you will have far better sound and impact. The voice coil temperatures will be lower and if you use smaller cones, better control and "snap". A box the proper size (B4 for example) will also give you higher efficiency.

Look at the problem again. You do not really want more power, you do want more bass (I guess). Don't design a sub box for power handling, design it for efficiency and the cutoff frequency. Use two drivers that match the box. Again, look at efficiency and f3 and the other T/S parameters.

If you could achieve your goal using 1/4 the power, wouldn't you want to?

-Chris

dhoover · 30th August 2006, 12:01 PM

I have only one Dahlquist DQ-1W sub that really likes 200 W.
I'm moving up from the Dahlquist passive sub crossover to an active and thought I might use the Adcom to power the 1W.
I'm using an old BGW now, but it has started to hummmmmmm!

anatech · 30th August 2006, 10:17 PM

Hi dhoover,
The Adcom is a decent amplifier, it's a keeper. One channel would do, because bridged will only be a little louder.

Your BGW is a good amplifier, old tech but certainly good enough for a sub. Fix it properly.

-Chris

29th August 2006, 03:55 PM	#1
dhoover diyAudio Member Join Date: Aug 2006	Adcom GFA-545 II bridging question Is there any way to bridge this amp for mono use? I've searched the web and emailed Adcom. Response from Adcom is that there is no way (not surprised). I don't feel like retiring this amp entirely. Thanks

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30th August 2006, 01:55 AM	#2
djk diyAudio Member Join Date: Feb 2001 Location: USA	It's a lot of work, and would only drive an 8 ohm minimum load. I wouldn't do it.

30th August 2006, 02:29 AM	#3
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi dhoover, Why would you do this for about +3dB? If you consider driving a pair of subs, one from each channel, you will have far better sound and impact. The voice coil temperatures will be lower and if you use smaller cones, better control and "snap". A box the proper size (B4 for example) will also give you higher efficiency. Look at the problem again. You do not really want more power, you do want more bass (I guess). Don't design a sub box for power handling, design it for efficiency and the cutoff frequency. Use two drivers that match the box. Again, look at efficiency and f3 and the other T/S parameters. If you could achieve your goal using 1/4 the power, wouldn't you want to? -Chris

30th August 2006, 12:01 PM	#4
dhoover diyAudio Member Join Date: Aug 2006	I have only one Dahlquist DQ-1W sub that really likes 200 W. I'm moving up from the Dahlquist passive sub crossover to an active and thought I might use the Adcom to power the 1W. I'm using an old BGW now, but it has started to hummmmmmm!

30th August 2006, 10:17 PM	#5
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi dhoover, The Adcom is a decent amplifier, it's a keeper. One channel would do, because bridged will only be a little louder. Your BGW is a good amplifier, old tech but certainly good enough for a sub. Fix it properly. -Chris

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