Bridging Amps from Different Brands

henesy

Member
Is this a bad idea?
I have two 100 watt rated amps, one a HK Citation 19, the other an AMC SPA 2100. They both have bridge switch/inputs. The power rating for C19 goes up to to 200 in bridge mode, for the AMC, 250. I have followed the available online instruction and have them running through an Adcom GTP-400 or Onkyo P-304 pres into a pair of Mission 774 speakers. Sounds pretty good! Especially with my Legendary Concept 2Qd as a source, there is something magic about having all that extra power-the audio just sounds effortless.

I don't need to do this exactly, just tinkering(obviously I have lots of amps with lotsa power), I haven't found a definitive answer online to what might be an obvious question.

What could happen?
 
you should have 1 channel louder than the other..?....maybe using the balance on your pre you can equal but i thought bridging needs to be the same...by-amping can be different if you can control the bias...

i do believe...
 
Are you trying to run them separate i.e. one for left, one for right channels? If that's the case, it shouldn't really matter except they'll sound different obviously. If you are just using them for low-end sounds, it wouldn't be as obvious though the speakers wouldn't be exactly matched. If you are talking about strapping them together (if that's even possible with home audio) I'd only stick with what it's meant to be strapped to.
 
gosh gentlemen...

I am doing this bridged amp business with out really knowing the theory behind it. my understanding is that each amp powers a channel from my pre.

well, here are some pics

the Citation 19 is powering my left speaker the AMC 2100 my right. Both are set to bridged mode. I found some instructions on line about how to do this.

I don't hear a sound difference per se-one channel doesn't sound louder than the other.

I suppose the question I had was if this was somehow bad for any part of the amp-preamp system if the amps aren't quite the same.

here are the specs
AMC 2100
http://www.amchome.com/content/amc-2100mkii-stereo-power-amplifiers-100w-x-2
HK Citation19
http://www.audiocircle.com/index.php?topic=69409.0
 

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The main differences are the input impedance mismatch 22k/32k and output wattage. Technically there should be a mismatch in volume from one to the other, but you may not be able to hear that with music, only a sine wave type of signal will reveal this. The other differences between amp sounds are most likely so small that you will never hear it. This includes how the amps switch from Class A operation to Class A/B operation. The bias settings in each amp will allow this to happen at different times and may change how the amps sound as the levels increase. Again, this is most likely small enough that you may never hear it, just as you can't tell whether or not the bridging made any difference.

Typically, bridging as you are doing it is done with identical amps to remove the negative affects of any differences in design that exist.

The way you are doing it isn't really any different that running one channel through your Adcom and one through your Onkyo, just because you have 2 separate preamps doesn't mean you should use them.

The extra power that you gain, in most people eyes isn't worth the possible mismatch.

In my opinion, the sound of your legendary turntable is being disrespected in the amplification process with the method you have chosen, but that's just me......
 
Dennis

Thank you! That's clear and makes sense.

Just tinkering around, and it's true, just because I can do a thing doesn't mean I should.

I guess I'll do an amp to amp comparison and see if vintage HK sounds better than recent AMC.

Peace!
 
sell the one you don't like as much and get another of the one you do like...

then make a proper bridge....which I'm in the process of doing this...it takes some time because my amp is really mint and want to find another one just as...
 
sell the one you don't like as much and get another of the one you do like...

then make a proper bridge....which I'm in the process of doing this...it takes some time because my amp is really mint and want to find another one just as...

Each amp is properly bridged. There are no connections between the two power amps. The current setup is just fine.

Henesy:

Try this experiment:

Switch the preamp to mono and then swing the balance back and forth between full left and and full right, listening for any differences. If there are swap the speaker leads at the amps so that the "left" amp powers the right speaker and vise versa. Test again. If the difference "swapped" sides, then you are hearing a difference in the amps. Decide if you can live with it or you want to to do a sell and buy swap. If the difference stays with the the original speaker (didn't change sides) any difference you heard is due to room variations and speaker placement so just keep doing what you are doing. (By the way, the balance control will be reversed in the second test, don't worry about it. It's normal when you reverse just the speaker connections). This will tell you if you can actually hear any real differences in the quality of the sound you are getting from the amps. I'm guessing the only difference "might" be a small volume difference. Easily dealt with by the balance control on the preamp.

Have Fun!

Shelly_D
 
Mission 774 is bi-amp capable? Should be.

Try one amp on the high band and other amp on woofer. Suggest the 19 on top and the 2100 on bottom. No need to bridge plus you get equal sound L to R.
 
Wow!

Look at all this cool audio advice!
The bi-amping suggestion sounds kinda cool. Let you all know how that works out.

AK is the greatest hobby forum in the universe. Yes!
 
are you sure you have the speakers connected properly ? ..
looks to me like you should be using both + connections ...one on the left as + one on right as - ...
look at the diagram on the back of the amp ..
 
are you sure you have the speakers connected properly ? ..
looks to me like you should be using both + connections ...one on the left as + one on right as - ...
look at the diagram on the back of the amp ..

the AMC design is interesting

-R+ +L-
When you hit the bridge switch for mono you pipe out the channel to speakers via the right terminals.

HK is
+ +
R L
- -

when the bridge switch is hit the left channel on the amp is used.

I looked up the bi-amping idea, I don't think that I have the proper preamp for that, there are only a single set of outputs on both of mine, so I can only do mono for each amp. Bi-amping sounds cool, and if I ever get a surround sound receiver I will play with that.

To my ears, the sound(nice!) is equal from both amps, the output needs no balance adjustment. Classic rock loud is pretty awesome-i put on the Grand Illusion and let Styx take me on a journey. Loud loud loud is pretty great with no distortion!

Hey, this is all a fun way to while away a lazy rainy Seattle day.
 
...I looked up the bi-amping idea, I don't think that I have the proper preamp for that, there are only a single set of outputs on both of mine, so I can only do mono for each amp. Bi-amping sounds cool, and if I ever get a surround sound receiver I will play with that....

Use a Y-splitter after the preamp so you have two sets of the same signal going into your amps. This way, your amps can run in normal mode.
 
Yeah, but SoCal is suggesting to stop the mono bridged arrangement and instead try a horizontal biamp setup. In horizontal biamp the two amps are both used in 2-ch/stereo mode.
 
Use a Y-splitter after the preamp so you have two sets of the same signal going into your amps. This way, your amps can run in normal mode.

Hats off to SoCal Sam! I did just this and piped all that through my new Bi-Amp capable B&W DM630s.

Uh, wow!

I was wondering if there was going to be a degradation of signal with the Y-cabling. I don't think so...


I'm just getting into listening to the new set-up. I'm getting goose pimples! Seriously! The sound difference is profound!

I didn't know things could be so improved. Wow!
 
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