Bi-amp for power?

zingo

Ideally, for a power hungry pair of speakers that you want to feed 1000wpc, would it be better to passively bi-amp them with 500wpc, or single amp them with the 1000wpc? I've heard there can be weird artifacts created in the vocal range by splitting the power between two amps, but I've never heard it for myself.

Opinions?

tonyb

What speakers are you talking about ? Don't know too many that can use 500 watts on the top end. I would be more apt to use monoblocks with single wire connections.

SolidSqual

500 or 1000 real watts of power that are actually produced by a well-designed product can drive any speaker most people will ever see in their home. Bi-amping makes far more sense if you goal is to remove the negative effects of a passive crossover via the use of an active crossover, or to gain the benefits of different sounding amps such as a tube amp on the highs with a SS amp on the lows.

Also, for clarity sake, Bi-amping uses two channels to power a single speaker. Using two monoblocks with a splitter cable is not really biamping.

FTGV

zingo wrote: »

I've heard there can be weird artifacts created in the vocal range by splitting the power between two amps...

Certainly the overall frequency balance can become skewed if the gains of the amps are disimilar and or if one inverts absolute phase.

zingo

I'm in talks for a pair of Carver Amazing Platinums, and I know they like power. I have my 440wpc at 4 ohms class D amp which is plenty of power for most speakers, but the speakers do have two pairs of binding posts for bi-amping, and I could move to a 4 channel amp that does 600wpc to drive to the woofers and ribbons.

With the benefits I've seen on TNRabbits active bi-amping for the Carver ALIIIs, I would assume the same would apply the the Amazings; and would be easy to do as they are only 2-way speakers.

FTGV

Well if your considering going fully active,IMO if done correctly could offer important benifits whereas with passive biamping I have my doubts as to it offering any substantial improvements assuming the single amp has adequate power to drive them.

unc2701

Those are an exception: Normally I'd say 1000 watts is better than biamped 500 since the most the time the upper binding post is just the tweeter and it's not going to use all that power and with the 1000 watt scenario, the crossover will direct the proper ratio of power to the two sections.

In this case you've got a real advantage for biamping. First, do you happen to know panel section even has a crossover on it? A lot just use the natural mechanical rolloff of the panel... Point being, if you biamp, you might not have a crossover in the picture at all for the panel.

You can also do a semi-active crossover. Leave everything in the speakers, but for the signal to each amp cut out the freqs about an octave or so beyond what it would handle. So if the woofer crosses in at 100hz, cut out everything going to the woofer amp over 200. Cut out everything going to the panel under 50hz. You don't have to mod the speakers, but you free up the amp to _mostly_ focus on the freq's it's handling. This will give you bigger gains on the high end since it's not chewing through power to amplify signals that just get turned into heat in the crossover/freqs that the panel won't reproduce.

tonyb

SolidSqual wrote: »

Using two monoblocks with a splitter cable is not really biamping.

Didn't mean to suggest that Mike, I ment mono's with just a single speaker cable, no bi-amping, totally agree otherwise.

Asa side note, where ya been ? Hows married life treating you ? Still creaming your shorts with those Hawthornes ?

FTGV

unc2701 wrote: »

You can also do a semi-active crossover. Leave everything in the speakers,....

This IMO defeats one of the main benifits of going active,vs a hybrid aproach.Since if as you say the woofers low pass filter is in the 100hz region one can assume a very large series inductor and it's associated DC resistance and it's negative effect on damping. Going fully active allowing the removal the large coils will allow the amp to be directly coupled to the woofers which should result in improvements in the bass range because of the increased control the amp has over the woofer due to the increased damping.

tonyb

Never heard of "semi-active" before. I only use that terminolgy to describe my sister in-law.

zingo

I agree. The main reason to go active is to remove the lossy, passive crossover components, and the hybrid approach does not accomplish that.

zingo

This picture alone looks like a good reason to do active...

pdxfj

The only time I've ever run into a true Bi-Amp setup was in the Planetarium I use to take care of. All the speakers were Renkus-Heinz, consisting of four 2-way cabinets each with a 15" woofer and a horn, along with a separate bank of four 18" subs. All signal processing was done by their Active Crossovers.

The XO's would take the input signal, and split it to HF and LF for the mains, and a sub out. Each main was driven by it's own 2-ch amp in stereo mode. Left channel ran the woofer, and the right channel ran the horn. Each sub had it's own dedicated amp.

It wasn't the greatest setup, but worked ok. My predecessor(s) didn't fully understand how to setup everything correctly. Someone before me had installed 30 band EQ's which didn't help things...

No idea how this fits into the discussion, but thought I would share my experience in hopes of helping someone better understand what a bi-amp setup is.

Gadabout

For those that would like to read more on the subject:

Benefits of Bi-Amping (Not Quite Magic, But Close) - Part 1

Scott

unc2701

FTGV wrote: »

This IMO defeats one of the main benifits of going active,vs a hybrid aproach.Since if as you say the woofers low pass filter is in the 100hz region one can assume a very large series inductor and it's associated DC resistance and it's negative effect on damping. Going fully active allowing the removal the large coils will allow the amp to be directly coupled to the woofers which should result in improvements in the bass range because of the increased control the amp has over the woofer due to the increased damping.

Agree completely, however, there's two benefits to active biamping- the direct coupling that you mention and the gains from having each amp only do part of the range. The lowest octaves take the most power and put the most strain on an amp. Granted, with these, cutting out under 50 won't do a ton, but it's something without completely rebuilding the speakers. Also, knowing Bob Carver, that crossover is doing a little bit more than just splitting the signal into high and low.

So- fully active bi-amp is certainly better, but to do it right, you'll probably need a DSP to put back in some of what you take out when you remove the crossover. Semi-active is a good compromise. It's even in the SDA manual; see page 8 here:
http://www.polksda.com/pdfs/SDASRS1-2.pdf
The gains for an SDA setup would be a little more, since you're cutting under 300hz for the top section.

TNRabbit

There are two good threads on biamping Carver Amazings. One is specific to Original ALS modified with the Platinum upgrade & the other is my own AL-III mod/build thread:

http://thecarversite.com/yetanotherforum/default.aspx?g=posts&t=1180

http://thecarversite.com/yetanotherforum/default.aspx?g=posts&t=3174

I also have a somewhat duplicate thread here on my mods but it's not as complete:

http://www.polkaudio.com/forums/showthread.php?103183-*-Gone-Active-*

The Amazing Platinums cross over at either 120 or 150 hz. Also, the crossover includes some tailoring to remove a couple of cavity-induced spikes around 2600 hz & 5800 hz.

TNRabbit

Funny, just found this post in my active thread:

zingo wrote: »

As much as I would love to go active with my speakers, it creates so many cables and components! There is something very nice to be said about an integrated amp and passive crossover in the speaker...

zingo

TNRabbit wrote: »

Funny, just found this post in my active thread:

I think I had a pair of 4 way speakers back then, which was not a fun thought. Nice find!

SolidSqual

I think you should pickup a cheap Behringer DCX 2496 to test out the benefits of Bi-Amping with Active Crossovers. If you got more cash, check out TC Konnekt, Apogee or Prism. You could even get two DSPeaker Anti-Mode Dual Core 2.0 units, thereby gaining the ability to biamp and room-correct the channels.

unc2701

SolidSqual wrote: »

I think you should pickup a cheap Behringer DCX 2496 to test out the benefits of Bi-Amping with Active Crossovers. If you got more cash, check out TC Konnekt, Apogee or Prism. You could even get two DSPeaker Anti-Mode Dual Core 2.0 units, thereby gaining the ability to biamp and room-correct the channels.

If you have less cash check out:
http://www.minidsp.com/

You could use the 2x4 model for just $125.

Good writeup one model here:
http://www.hifizine.com/2011/06/tour-of-the-minidsp-2x8/

It's pretty great to have just for playing around- I can't design a crossover to save my life, but you can tweak around the parameters in there and play around with throwing any two drivers together. And how wrong can you go for $125?

Blownrx7

FTGV wrote: »

Certainly the overall frequency balance can become skewed if the gains of the amps are disimilar and or if one inverts absolute phase.

I've heard something like this also. Dave Schulte at the Upgrade Co commented to me once that he biamped with identical amps to avoid phase shift and gain issues.

gp4jesus

FTGV wrote: »

Certainly the overall frequency balance can become skewed if the gains of the amps are disimilar...

A valid issue thought one that I'd think any EXO would have the means to adjust to overcome - all of mine do.

FTGV wrote: »

...or if one inverts absolute phase.

An amp either inverts phase or it doesn't. Connect each amp to matching speakers, power up your system, & listen. Reverse speaker polarity on one channel & listen. The setup w/ the centered, louder bass has the amps in phase.

I admit if you're doing a 3 or 4 way system this can get hairy. Decide which amp is your reference then label the others accordingly. Back in the '90s I did the above to enjoy a squeaky clean, near club level, 4 way, 2 channel system.

Have fun w/it. Tony