|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
184.107.226.106
In Reply to: RE: Bi-amp fail and Amy Winehouse posted by kSpace on January 31, 2017 at 09:32:34
Ok, I have said it before. Biamping at the speaker level is a waste of time. In order to get the benefit of biamping, it has to be done at the line level - either actively or passively - and this becomes a big deal. Slopping a 4th order L-R at the approximate crossover frequency just ain't gonna cut it. The crossover has to be carefully designed to match the OEM that the manufacturer had in mind.
When one biamps at the speaker level there is no real crossover. What one has, is two parallel filters neither of which interacts with the other (i.e. the "rejected" high frequency from the low pass filter does not crossover to the tweeter and vv). This was not what the manufacturer set out to do.
Others may disagree, but they are wrong :).
I married the perfect woman. The downside is everything that goes wrong is my fault.
Follow Ups:
I completely disagree,Im not wrong and have been horizontally passively biamping with great benefit and no downside for over a decade. I used the exact same setup with one amp first then added the second so I KNOW.The speakers are two way and cross at 2.5K. You dont need an active crossover to prevent the HF amp from wasting its power on (unused) LF information for instance. With info fed to the HF amp the crossover in the speaker filters out everything below 2.5K at a third order slope (in my system). Because the LF info is filtered out and unused there is no load at those frequencies. No LF info has EVER lit the peak lights on the CJ amp, only midrange info like a snare hit, piano note or guitar twang has lit it. What does that tell you? The same is the case on the LF amp with HF info although one would likely not see the result of this ever anyway as bass consumes much much much more power. Frequencies under 300hZ likely consume 70% or more of an amps total power running full range. You know that right?
Passive biamp requires very stringent adhesion to the following IMO
1) same input Z, gain and sensitivity amps
2) horizontal for more equal loading of the amps channels
Oh wait thats it its actually pretty easy. However well over 90% of the time number one is not followed. I even recommend same manufacturer for the same voicing. I hope you are not one of these all amps sound the same folk too.....So tell me all the particulars of the horizontal passive biamp(s) you have implemented that didn't work for you? I hope you are not one of those people that decides everything based on theory and numbers without actually trying.....this place is full of those types.
ET
"If at first you don't succeed, keep on sucking till you do suck seed" - Curly Howard 1936
Edits: 02/02/17
I am happy to agree to disagree with you about speaker level crossover and I am glad that you are pleased with your setup as that is a goal for all of us.The gain and sensitivity of the amp are essentially the same thing - just expressed differently (mathematically) and I absolutely agree that the two amps need to jive regardless if the crossover is at the line-level or speaker-level. Not having the same gain or having a means to equalize the gain will doom any attempt at biamping. And I also agree with you that it is better to have the amps from the same manufacturer if not from the same series or even better identical. I don't know where your comments about all amps sound the same came from, but that premise is as ludicrous as saying all speakers sound the same - we are in agreement about that.
I am not sure about the impedance of the amps being the same but I will concede that to you without any knowledge to say otherwise. As far as the 70/30 power split at 300 hz, I thought it was 50:50 - I refer to the article by Rod Elliott . Regardless one must also consider the sensitivity of the drivers and the type of music. For example if one likes a lot of bass heavy rock music then the power requirements on the low end may need to be more than those who listen to opera. Clearly if the bass driver is not as sensitive as the tweeter either more bass power is required or a padder is needed on the tweeter. Again this is true whether the crossover is line-level or speaker-level.
Finally I am not sure I follow you on using a horizontal (v vertical) arrangement of the amps to even the power load. With horizontal one stereo amp feeds the bass channels and the other the treble channels, so it would seem the power supply of "bass" amp would be doing more work than the PS of the "treble amp" - at least if you follow your 70:30 rule. It would seem to me that a vertical setup (one stereo amp for each speaker) would even out the load better. I am not disputing your statement that horizontal is better for speaker level biamping, I just don't follow the logic. To be clear I have not done speaker level biamping in over 30 or more years, so I will concede any argument about the fine points to you.
Oh yeah, I am not a "theory purist". I have had Magenpan speakers for almost 40 years (shit I am getting old) and have always had them biamped one way or another until I got the 3.7i which unfortunately have a series XO and are not readily amenable to biamping.
BTW, I do not like to use the term "passive biamping" as it is confusing. While speaker level is passive, not all passive biamping is at the speaker level. Line-level biamping and can be active or passive - I have used both. One other point, with the Magnepan speakers, which are notorious power hogs, I have used line-level crossover with superb results. Speaker-level was not as successful. With other speakers that don't suck up watts like the Magnepans, the line-level biamping may not be as advantageous. The point being that different approaches are needed for different systems. That is why I put the ":)" in my first post "Others may disagree but they are wrong :)" .
I married the perfect woman. The downside is everything that goes wrong is my fault.
Edits: 02/03/17 02/03/17
Thanks for the detailed reply. I have always heard the horizontal is left right and vertical up down so vertical has one amp per speaker horizontal one amp per section if you will which in my case is LF/HF.
Cheers!@
ET
"If at first you don't succeed, keep on sucking till you do suck seed" - Curly Howard 1936
I follow your comments about the parallel inputs to the speaker not interacting through crossovers in the speaker. I am confused as to your comment about it needing to be line-level. I split the output to the amplifier channels at the preamp audio out RCA jack, is this not line-level? Where else can I split the signal for each channel to get the bi-amplification of the speaker?
If I am understanding correctly, are you suggesting an external crossover that splits the high and low frequency from dual amplification for each channel prior to connection to the speaker?
And so... Output from two amp channels into left and right external crossovers, then dual outputs to the high and low frequency speaker posts?
Seemed to me that the internal crossovers would handle the full range inputs from the amplifier to the high and low freq posts and voila!, great sound. To me, it seemed more of a phase coherence problem - cables not perfectly matched or amp channels not identical.
Sorry if I seem confused... want to learn from my mistakes. Prob my next move is to call Revel..
Thanks for your feedback!
If I read your post correctly, you are taking the full signal from the preamp and splitting it into two parallel but identical signals. For the most part this is fairly innocent but this is not a crossover*. From there each amplifier is fed a full signal and only when the signal reaches the speaker crossover is the signal divided into high and low frequencies.
Here is a diagram of a vertical active biamp setup which uses to identical amps:
and a diagram of a horizontal setup which is generally used if the amps are different but could be also be used for identical amps.
* I say fairly innocent because in the rare case of using a tube pre-amp [these typically have a relatively high output impedance (> 1 kohm)] with some SS stereo amplifiers that have low input impedances, the desired ratio of > 10:1 (load to preamp out) may not be maintained. Signal splitting puts the two amplifiers in parallel and the load impedance seen by the preamp is halved.
Specifically in your case the Halcro has 10K ohm impedance which when split puts a load of 5000 ohms on your preamp that has an output impedance of 300 ohms (unbalanced). This means the ratio is 17:1 - this should be ok. However if you are using the balance connectors then the preamp impedance is 600 ohms and the ratio would drop below 10:1.
I married the perfect woman. The downside is everything that goes wrong is my fault.
Edits: 01/31/17
You have summarized my prior "bi-amp" setup correctly. Counted on the speaker network to handle the crossover duties. If one feeds the speakers from an external crossover, as your diagrams show, wouldn't the resulting signal be subject to additional filtering in the speaker?
Anyways. Probably gonna walk away from this one. The sound without "bi-amping" is so wonderful that I pray that nothing breaks for the rest of my life! (haha)
Thanks again for your help. Great diagrams and you clearly looked up the specs on my equipment, so thank you for that too!
Best wishes!
Post a Followup:
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: