Can/should you mix power amps?

[Shaun @ Tru6]

I've got a Hafler power amp driving a pair B&W speakers. A friend is giving me his old smaller B&Ws which I think will complement mine very well.

Old power amps like the Hafler seem to be cheap and plentiful. Would an old Adcom work with or fight against the Hafler? or not at all, just get whatever.

[Superman]

You cannot connect two amps to the same speaker. But you may be able to "bi-amp" the speakers if they are two or three-way and allow for independence between the woofer and the rest. Here is a pic of the back of one of my speakers. Ignore the dust. The metal strips connect the woofer circuit with the mid and tweeter horns. If I wanted to "bi-amp" and use two power amps, I would remove the metal strips and connect one amp to the upper terminals and the other amp to the lower terminals.

But no, you cannot electrically connect two power amps to each other in any way.

[Superman]

You could also get a subwoofer and/or a dedicated woofer ("bass bin"), and connect one amp to the woofer and the other to the B&Ws. And use a crossover or high pass filter to keep the low frequencies out of the B&Ws.

Okay....now I see I misread your question and fact set. Yes you can feed two power amps from a preamp, or from two preamps, with each power amp driving its own pair of speakers. You can probably also connect both pairs of speakers to your amp, depending on the minimum amount of impedance your amp needs to 'see.' Often, power amps will tolerate a 4-Ohm load but not a 2-Ohm load. If each of the speakers are 4-Ohms, then this would create a (likely impermissible) 2-Ohm load. If each of the speakers are rated at 8 Ohms, then you are likely good to go connecting both pairs to your amp (since your amp very likely will handle a 4-Ohm load).

[masraum]

Originally Posted by Superman

You cannot connect two amps to the same speaker.

I think he's wanting to connect his current speakers to the Hafler and the 2 new speakers to a different amp, 2 amps and 2 pairs of speakers. I don't think (maybe I'm misunderstanding) he's wanting 2 amps one one set of speakers.

[Superman]

For reference, even though this is not your question, here is the pic I forgot to clip:

[908/930]

What are you using for a source, does your pre amp have two sets of line outs? If so, no problem it will work fine.

[Superman]

You can feed two power amps from the same preamp using a simple y-cable, no problem.

[Superman]

You just won't have separate volume controls. That's easy to add. I have a Schiit "SYS" which is just three inputs, a switch for the inputs, a single pair of output jacks and a volume control. $49.

[Shaun @ Tru6]

I'll have to look at the back of the Rotel but am assuming it has two sets. All good info, thanks guys.

[Superman]

I see Hafler and Adcom in your OP and now Rotel. At any rate, you can use one amp for this, or two, and you can surely get cabling for that if your amps do not have the 'bare wire' binding posts. But you do need to give your amp at least an X impedance load. If your amp is not rated for less than a 4-Ohm load, then you cannot connect two 4-Ohm speakers per channel. That would present your amp with a 2-Ohm load and that's not okay. But your amp almost certainly can handle a 4-Ohm load and if so, and if your speakers are 8-Ohm (likely), then you are good to go.

Also, if the two pairs of speakers are different models, even if they are the same brand, then you will want to check their sensitivity. If their sensitivity ratings are different, and certainly if they are much different, this can be important. Loudness is somewhat subjective, but basically a 96 db speaker is going to be roughly twice as loud as an 89 db speaker. Even a 3db difference is going to be enough you will notice. I have tried using speakers with mismatched sensitivity and it really doesn't work for me. one or two db, maybe. More than that, not so much.

[Gogar]

I like what Superman is saying but he's muddying the water with way too much (albeit worthy) information.

So you mean you want to use a new amp with your newly gifted speakers?

Sure! Enjoy. Don't play both sets of speakers at the same time, unless it's a house party. It's just not a thing.

If you can discern which amp is better for which set of speakers that's great and you are in the top 2% of people who can do such a thing. Basic power ratings and such aside.

You could get a basic speaker switcher and use the same amp for both sets of speakers and switch between the two and have a little comparison fun that way if you like!

[Shaun @ Tru6]

I want to run both sets of speakers at the same time, louder. My friend's B&Ws are smaller towers than mine and cleaner and brighter.

I like my Hafler 230 Pro amp but it isn't very loud, though even at volume 8+ there is zero distortion. I would love to get an Adcom 555 for my speakers and use the Hafler for the new ones or I have thought of just getting another B&K AVR 307 with tons of power to spare and running all 4 speakers off it.

I feel like the speakers will complement each other, the smaller filling in brightness and details that the larger doesn't do very well.

[Gogar]

Ok, cool!
At that point then yea you should probably have 2 amps and use the higher power amp for the higher rated speakers.

It is (usually) technically possible to run 2 speakers on each side of a capable amp but if the speakers are a little mismatched in their capability or sensitivity then you have no way to adjust "how much" power is getting to each speaker.

Almost like if you had 4 disc brakes and sent equal power to all 4 equally and the fronts want more and the rears want less. (Car forum )

You would have more tweakability and safety if you have an amp dedicated to each set of speakers.

[Shaun @ Tru6]

Thanks Jeremy, this more leads me to the B&K. the amount of detail you can program into each channel is staggering. Overkill for me but I could adjust the loudness of each speaker pair easily with the 307. and they would be extremely loud. Something to think about.

[908/930]

An Adcom 555 would be a much better than the shared amps that are in the B&K307, the original 555 design being done by Nelson Pass. If you end up with speakers that are harder to drive the stand alone amp will sound much better at high volume.

The last time I listened to a 555 was on a friends system in the 80's, he was driving a pair of Klipsch La scala's, was certainly capable of going to high volumes.

[Superman]

Well Jeremy is right and I do tend to over-complexify things but though I'd like to stand down I can't do that just yet. He is also correct about having a way to adjust the signal independently for each pair of speakers, particularly if the sensitivity ratings of those speakers are not the same. I can't stress this enough. A handful of db means double the loudness.

So important is speaker sensitivity to loudness that it totally eclipses wattage. Listen up: In order to get double the loudness from a speaker, you need to use TEN TIMES the wattage. Look it up. This is important. My home stereo power amp makes 8 WPC, but it is driving a pair of 102db speakers. you would not believe the loudness I can achieve.

I do disagree with Gogar about using two pairs of speakers. I have done this many times. In fact, we bass players know that the way to deal with a loud drummer is to use more paper (speaker surface area), not more watts. More paper will get you more loudness for sure. And it can totally work. Heck....modern systems are five-speaker systems, with two in front, two behind and a subwoofer. They should all be about the same distance from the listener, BTW, for phase reasons.

Yes, another power amp driving another pair of speakers can help. "Can," but your ears should decide. And if your speakers are rated down in the mid 80s db or below, then this is why they are not getting loud.

[Superman]

Klipsch La Scalas are 105db!!!! This means that if you feed them one single watt, they will each be as loud as a lawnmower. No joke.

[sc_rufctr]

From Legacy Audio.

Horizontal Biamping
Any two stereo amplifiers may be utilized in horizontal biamplification.
Many audiophiles prefer the "sweetness" of tubes on the satellite portion
of the loudspeaker while favoring the "control and weight" of solid state
amplifiers on the subwoofer section. The biggest drawback of such a
marriage of amplification is that the two amplifiers may have different input
sensitivities or output polarities. Differences in the input sensitivities may
be overcome by using a dual amp balancer. This unit allows independent
balancing of the left subwoofer/satellite ratio and right subwoofer/satellite
ratio. It's also a good idea to check the owner's manuals to establish if the
amplifiers are inverting or non-inverting. If the two amplifiers are of
opposite polarity, then you should reverse the polarity at the inputs of
either the subwoofer or satellite binding posts.

NOTE: This only applies to
loudspeakers that incorporate the subwoofer and satellite section in a
single enclosure. It does not apply towards the separate powered
subwoofer/satellite configuration. You must always observe the polarity
when connecting the speaker wire to a powered subwoofer.

[Gogar]

Good paste but This isn't about biamping.


I agree supe, if he just wants to be loud and have some fun then of course four is fine. I just meant if he's sitting in between a set of speakers and getting super listeny then four isn't generally a way someone would go.

[Shaun @ Tru6]

Originally Posted by 908/930

An Adcom 555 would be a much better than the shared amps that are in the B&K307, the original 555 design being done by Nelson Pass. If you end up with speakers that are harder to drive the stand alone amp will sound much better at high volume.

The last time I listened to a 555 was on a friends system in the 80's, he was driving a pair of Klipsch La scala's, was certainly capable of going to high volumes.

Thanks, this is good to know.

I may end up experimenting a little if amps are more on the liquid side.