Very strange problem when bi amping

[brad1138]

I have a Citation 5.1 and a BIAMP (that's the brand name) Eminence 300. The Citation is a 4 chan amp at 100wpc/8ohm-175wpc/4ohm. The Eminence 300 is 2 chan 100wpc/8ohm-150wpc/4ohm. Both are great amps. The Eminence 300 has a cleaner sound with better imaging while the Citation 5.1 has a "fuller" & slightly more accurate sound.

I usually use the Citation in 4 chan mode to vertically bi-amp my M-3sis (it has a dual mono design), but occasionally I want to switch the mids/tweets over to the eminence 300 for its different qualities.

The problem is I am getting a crackling through the mids/tweets at moderate volumes when I hook the mids/tweets to my Eminence 300 and leave the woofers hooked to the Citation. However when I hook both the mids/tweets & the woofer to the Eminence I get no crackling even at higher levels (I am not bi-amping in this config). So I have no problems when I run them just on the Citation in 4 (or 2) channel mode and I have no problem when I run them on just the Eminence. But when I try to use both amps I have a problem.

I have a few more test I want to try, like just running the mids/tweets with the Eminence and not even hooking up the woofers to see if I still get the crackling.

It makes no sense why I would have a problem with just the mids and tweets and not the whole spk, it should be harder on the amp to run the whole spk.

The only thing I can think of is some kind of conflict between the 2 amps. They are spaced about 2 inches apart in my rack. Both amps are plugged into my Adcom line conditioner and have grounded plugs. I know the phase is correct. Is it possible that one amp could be wired internally out of phase? Would that cause any problem other than sound quality?

The crossovers are still intact and being used in the M-3sis, I know this isn't "true" bi-amping.

Anyone have any Ideas?

Thanks,
Brad

 

[yepimonfire]

i don't exactly know what you problem is but it sounds like the eminence is causing clipping, be careful and dont play anything on it for more then a few seconds because i ruined two $500 KEF speakers tweeters by using a poor quality amp that had clipping issues.

I know the phase is correct. Is it possible that one amp could be wired internally out of phase? Would that cause any problem other than sound quality?

an out of phase signal shouldn't cause crackling, what it would do is completly wipe out your bass and make the mids/highs sound directionless.

try using a different set of speakers with the eminence and see if it causes crackling.

and if it is crackling when using only the mids/tweets and not when driving the whole speaker, maybe (im not too sure on this) the amp is supplying too much power to the mids/tweets. when driving the whole speaker the power is distributed more evenly, when driving just the mids/tweets, it is able to concentrate the amps entire supply on them.

 

[brad1138]

and if it is crackling when using only the mids/tweets and not when driving the whole speaker, maybe (im not too sure on this) the amp is supplying too much power to the mids/tweets. when driving the whole speaker the power is distributed more evenly, when driving just the mids/tweets, it is able to concentrate the amps entire supply on them.

Thanks, I don't think that is it as the crackling starts at fairly low levels (about 85 db at listening position as per my Radio Shack meter) which should be less than 10 wpc from the amp. I think the fact that I can run the whole spks w/o any issues into the 90-100 db range shows my the amp isn't "crapping out" or clipping early.

I have been in & around the audio business for 20+ years and worked in an AV service department. This really makes no logical sense.

What I meant by out of phase wasn't for left vs right but for woofer vs mids/tweets. I would think it would mess up the sound quality at 350Hz (the crossover point for woofer to mid), but nothing else.

Thanks,
Brad

 

[yepimonfire]

hmmm this really does make absolutley no sense, but i would say if it makes it crackle, then dont do it because you wouldnt want your tweeters going out on you.

 

[adwilk]

Here's a crazy thought, and probably exactly what you don't want to hear...

Forget biamping. With the passive xover network your speakers are sporting, you're not gonna hear a difference. Thats assuming your amp has enough power to adequately power the speaker and I believe it does. Also, you mentioned some sound differences in the two amplifiers; those differences likey don't exist and its almost entirely placebo.

If you want more power, sell both amps and buy a bigger single one and forget about the waste of time that is biamping.

Now, if you decide to go fully active, then theres a different conversation.

 

[yepimonfire]

i honestly don't see the purpose in bi-amping, most home setup amplifiers have more then enough power to make your ears bleed.

and as far as the amps making a difference in sound, its possible, but not likely, most amplifiers sound the same unless you have a bad amp, if one of your amps has better sound then the other, it probably means that the other one is a piece of crap. i have two receivers, a kenwood and a marantz, the marantz sound 10x better, but i also know the kenwood is not a good amp because it for one blew out my tweeters from clipping. oh and as far as only supplying 15w to the mids and tweets, most of your power is used for low freqeuncys, the mids and tweets usually use about 20% of the power and the woofer uses the rest for bass output, low frequencies take more power because to create them you have to move alot more air and the movements have to be much wider to generate a longer waveform, you will notice you cant visibly see you mids or tweets vibrating, but you can easily see a woofer "pumping" in and out.

 

[highfigh]

Thanks, I don't think that is it as the crackling starts at fairly low levels (about 85 db at listening position as per my Radio Shack meter) which should be less than 10 wpc from the amp. I think the fact that I can run the whole spks w/o any issues into the 90-100 db range shows my the amp isn't "crapping out" or clipping early.

I have been in & around the audio business for 20+ years and worked in an AV service department. This really makes no logical sense.

What I meant by out of phase wasn't for left vs right but for woofer vs mids/tweets. I would think it would mess up the sound quality at 350Hz (the crossover point for woofer to mid), but nothing else.

Thanks,
Brad

85dB is less than one Watt. You're nowhere near 10W/ch unless the room is very large.

It makes sense- what was the most common thing that you remember causing crackles? Dirty controls and switches, right? Then, bad solder joints. After that, loose connections and farther down the list is actual component failure.

 

[highfigh]

i honestly don't see the purpose in bi-amping, most home setup amplifiers have more then enough power to make your ears bleed.

and as far as the amps making a difference in sound, its possible, but not likely, most amplifiers sound the same unless you have a bad amp, if one of your amps has better sound then the other, it probably means that the other one is a piece of crap. i have two receivers, a kenwood and a marantz, the marantz sound 10x better, but i also know the kenwood is not a good amp because it for one blew out my tweeters from clipping. oh and as far as only supplying 15w to the mids and tweets, most of your power is used for low freqeuncys, the mids and tweets usually use about 20% of the power and the woofer uses the rest for bass output, low frequencies take more power because to create them you have to move alot more air and the movements have to be much wider to generate a longer waveform, you will notice you cant visibly see you mids or tweets vibrating, but you can easily see a woofer "pumping" in and out.

Bi-amping is originally from pro audio, where the loss caused by passive crossover components would make more power necessary on the order of 2x (-3dB), 4x (-6dB) or more. Pro audio likes unity gain and hitting all of the reference levels and that's something consumer audio never tried to conform to. This is a huge mistake, too. Whereas much of consumer audio is basically compatible, almost ALL pro audio gear will work together without problems. Also, active crossovers, which are used extensively in pro audio, can have 24dB or 48dB/octave slope without all of the phase shift inherent to passive crossovers.

 

[brad1138]

Also, you mentioned some sound differences in the two amplifiers; those differences likey don't exist and its almost entirely placebo.

This isn't the direction I wanted to take this, but. Maybe you haven't spent a lot of time with high end spks & equipe (StereoPhile class b or better). I have, I used to sell them and I now listen to them almost daily. I guarantee you there is a distinct difference (I never said huge, my wife probably couldn't tell a difference, but I can). I also guarantee that neither is a piece of crap, they both are on par with Bryston, Aragon and the ilk. I have an Adcom GFA-545 amp of similar specs and the difference between the Citation/BIAMP amps and the Adcom are huge, the Adcom isn't even in the same league. I really can't take anyone seriously that says "all amps sound the same" If that were true there would be no market for anything more expensive than Adcom. Who would ever buy Krell or Mark Levinson?

The Mirage M-3sis are very power hungry speakers. They need 200+ wpc to really come to life. The Citation 5.1 is plenty powerful @ 4x100 or 2x300 at 8 ohms, but it sounds better in 4 channel mode. I balanced the level adjusts of the BIAMP amp to exactly match 2 of the 4 citation channels so that I can switch the mids/tweets between them while maintaining the proper balance between highs and lows. In case I didn't make it clear, when using the BIAMP amp I am leaving 2 of the 4 Citation channels idle.

For what it is worth I am biamping exactly the way the M-3sis owners manual shows. The advantage is that the amps running the mids tweets aren't bogged down running a large woofer. The difference may be subtle but it is there.

The main point here is that there IS a difference in imaging, vibrance & clarity between the 2 amps. I want to switch back and forth every month or so and the BIAMP amp isn't powerful enough to run the Mirages by itself. If I am not biamping the spks I have no way to switch back and forth the way I want.

That all being said, I still don't know what is causing the problem I posted about, I'll do some more tests to see if I can narrow it down.

Brad

 

[brad1138]

85dB is less than one Watt. You're nowhere near 10W/ch unless the room is very large.

.


The M-3si is 83db@1watt@1meter efficient (as I said, very power hungry) and are in a fairly large room, about 25x25+. I meant "at the most" 10 wpc, in either case, well under the rated 100wpc. I have eliminated any of the possible causes you mentioned, in that either amp can run them at least up to 100 db without any popping/crackling/clipping as long as it is just that one amp, the problem only shows when using the BIAMP for highs and the Citation for lows.

 

[highfigh]

.


The M-3si is 83db@1watt@1meter efficient (as I said, very power hungry) and are in a fairly large room, about 25x25+. I meant "at the most" 10 wpc, in either case, well under the rated 100wpc. I have eliminated any of the possible causes you mentioned, in that either amp can run them at least up to 100 db without any popping/crackling/clipping as long as it is just that one amp, the problem only shows when using the BIAMP for highs and the Citation for lows.

I didn't think they were that low in sensitivity.

Can you post a photo of the speaker's terminals with the cables attached?

 

[yepimonfire]

85dB is less than one Watt. You're nowhere near 10W/ch unless the room is very large.

It makes sense- what was the most common thing that you remember causing crackles? Dirty controls and switches, right? Then, bad solder joints. After that, loose connections and farther down the list is actual component failure.

yea, maybe at pure 1khz sine waves, your forgetting harmonics and actual music is involved

you try getting 85db at 100hz using one watt, not going to happen. this was the point i was trying to make earlier, bass uses more power then mid and treble. if this was the case that you can get 85db of sound out of 1w, then there would be no point in making 100wpc amplifiers. you try driving your massive floorstanders with the amplifier in your laptop computer speakers. with my music at a loud level, (loud enough that people would have to shout to get my attention) i draw around 50wpc, all channels driven and the sound is around 85db

 

[brad1138]

I didn't think they were that low in sensitivity.

Can you post a photo of the speaker's terminals with the cables attached?

Sorry, the picture is a bit fuzzy, I used my phone. I use banana plugs at the other end, they are similarly clean. The cable is 14 gauge and for what it's worth the woofer connection is on the left.

edit: I added this picture I found, hard to make a lot out, but this is the amp side.

 

[zhimbo]

if this was the case that you can get 85db of sound out of 1w, then there would be no point in making 100wpc amplifiers.

This is wrong on at least two levels. First, It isn't all that hard to get 85db from 1 watt - it all depends on the speaker. Get some typical Cerwin Vega speakers, and 1 watt will be excessive.

Second, even if you are getting 85db/1 watt there is still plenty of reason for 100 wpc. If listening at 85db to a movie soundtrack or an orchestra, you may be getting 20dB transients in spl. To do that cleanly you'd need...100 watts. (every 10dB increase requires a 10x increase in power: 1 watt x10 x10 = 100).

 

[adwilk]

This isn't the direction I wanted to take this, but. Maybe you haven't spent a lot of time with high end spks & equipe (StereoPhile class b or better). I have, I used to sell them and I now listen to them almost daily. I guarantee you there is a distinct difference (I never said huge, my wife probably couldn't tell a difference, but I can). I also guarantee that neither is a piece of crap, they both are on par with Bryston, Aragon and the ilk. I have an Adcom GFA-545 amp of similar specs and the difference between the Citation/BIAMP amps and the Adcom are huge, the Adcom isn't even in the same league. I really can't take anyone seriously that says "all amps sound the same" If that were true there would be no market for anything more expensive than Adcom. Who would ever buy Krell or Mark Levinson?

The Mirage M-3sis are very power hungry speakers. They need 200+ wpc to really come to life. The Citation 5.1 is plenty powerful @ 4x100 or 2x300 at 8 ohms, but it sounds better in 4 channel mode. I balanced the level adjusts of the BIAMP amp to exactly match 2 of the 4 citation channels so that I can switch the mids/tweets between them while maintaining the proper balance between highs and lows. In case I didn't make it clear, when using the BIAMP amp I am leaving 2 of the 4 Citation channels idle.

For what it is worth I am biamping exactly the way the M-3sis owners manual shows. The advantage is that the amps running the mids tweets aren't bogged down running a large woofer. The difference may be subtle but it is there.

The main point here is that there IS a difference in imaging, vibrance & clarity between the 2 amps. I want to switch back and forth every month or so and the BIAMP amp isn't powerful enough to run the Mirages by itself. If I am not biamping the spks I have no way to switch back and forth the way I want.

That all being said, I still don't know what is causing the problem I posted about, I'll do some more tests to see if I can narrow it down.

Brad

Provided that both amplifiers are working properly, then double blind testing would beg to differ with your statements regarding a difference in audible output. Unless of course you're the human anomaly, and CAN actually hear a difference. Amplifiers don't and shouldn't affect a sound signature, if it does, then it is malfunctioning.

 

[yepimonfire]

This isn't the direction I wanted to take this, but. Maybe you haven't spent a lot of time with high end spks & equipe (StereoPhile class b or better). I have, I used to sell them and I now listen to them almost daily. I guarantee you there is a distinct difference (I never said huge, my wife probably couldn't tell a difference, but I can). I also guarantee that neither is a piece of crap, they both are on par with Bryston, Aragon and the ilk. I have an Adcom GFA-545 amp of similar specs and the difference between the Citation/BIAMP amps and the Adcom are huge, the Adcom isn't even in the same league. I really can't take anyone seriously that says "all amps sound the same" If that were true there would be no market for anything more expensive than Adcom. Who would ever buy Krell or Mark Levinson?

The Mirage M-3sis are very power hungry speakers. They need 200+ wpc to really come to life. The Citation 5.1 is plenty powerful @ 4x100 or 2x300 at 8 ohms, but it sounds better in 4 channel mode. I balanced the level adjusts of the BIAMP amp to exactly match 2 of the 4 citation channels so that I can switch the mids/tweets between them while maintaining the proper balance between highs and lows. In case I didn't make it clear, when using the BIAMP amp I am leaving 2 of the 4 Citation channels idle.

For what it is worth I am biamping exactly the way the M-3sis owners manual shows. The advantage is that the amps running the mids tweets aren't bogged down running a large woofer. The difference may be subtle but it is there.

The main point here is that there IS a difference in imaging, vibrance & clarity between the 2 amps. I want to switch back and forth every month or so and the BIAMP amp isn't powerful enough to run the Mirages by itself. If I am not biamping the spks I have no way to switch back and forth the way I want.

That all being said, I still don't know what is causing the problem I posted about, I'll do some more tests to see if I can narrow it down.

Brad

they have a max input of 300w meaning thats their blowing point

your citation amp is capable of driving around 150w rms into them, that sound like plenty of power to me. now im all for saying that amps with more power output sound better but its not because your actually using all of that power, its because the amp is comfortable driving them at half the power, rather then straining it during musical peaks at its near max output. i challenge you to drive all four channels in a multichannel music mode like PL II and turn it up to your normal volume level and measure the output, you will probably be pumping no more then 50wpc. point being is this means you have alot of headroom, meaning your amp is capable of driving 3x the current needed for normal listening levels resulting in better sound because their are no strains on the amp to drive peaks such as kick-drum kicks, snare hits, bass guitar plucks etc. you will see the power go up and down between 30wpc-75wpc at a moderate volume level. you will never use up all that headroom, and thats a good thing because that leaves extra reserves for peaks.

 

[adwilk]

they have a max input of 300w meaning thats their blowing point

That blanket statement has several fallacies.

I'm not saying that it isn't necessarily true, but it isnt that simple and certainly not that absolute. Other factors would have to be considered.

As far as output goes and headroom and the like, again not as absolute as you stated. With out seeing the impedance curve, its impossible to determine actual wattage usage for any given SPL.

Also, as Zhimbo pointed out, actual programme has db peaks that could require massive amounts of power, especially in classical music. When one of these peaks also lines up with an impedance dip, even more power is required.

 

[yepimonfire]

thats kind of what i was saying, i wasnt trying to be absolute with my numbers, just giving somewhat of an example, my point was that their is no way that your going to get 85db of musical sound out of 10w in almost all cases (using large speakers). try listening to nile, theres parts of their music that will draw the entire 110wpc without using a very high volume.

 

[adwilk]

try listening to nile, theres parts of their music that will draw the entire 110wpc without using a very high volume.

Again, its just not that simple. There are plenty of speakers that wouldn't need that much power for virtually any music. A steady 8ohm speaker with sensitivity above 100 in a small room might never use that much.

EDIT: anyway, back to topic......

 

[yepimonfire]

those are my own measurments using my own equipment though