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Bi-Amp versus Amp Bridging (Read 11259 times)
Core32
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Bi-Amp versus Amp Bridging
11/01/14 at 02:53:42
 
My speakers are bi-amp capable, meaning there are three sets of binding posts, normally shorted together with removable gold jumpers.
These are rated at 90dB efficient but are quite old so I'll take that as best case efficiency.
My question concerns using two identical stereo amps that cannot be bridged to mono, to drive a single speaker each in bi-amp mode.
I assume I would do this by splitting one preamp signal feed (right channel say) and feeding it into both left and right inputs of the stereo amp, then take the left amp out to the "high" binding post on the speaker and take the right amp out to the "low" binding post on the speaker. Removing the gold speaker jumpers of course. Then do the same setup for the other speaker.
Do I have this correct? Is it a bad idea? Or is there an alternate hook up scheme to accomplish the same effect?
Thanks for your input and advice.
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Core32
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Re: Bi-Amp versus Amp Bridging
Reply #1 - 11/02/14 at 16:27:41
 
Maybe a little clarity would help me get some opinions Smiley
I can't really afford to start with a TORII MK4 with it's 25W but am concerned the 6W of the Rachael might not be enough for my older speakers.
Knowing I could double the power later by running bi-amp would convince me to go for it now.
Also, I understand the newer Rachael is capable of running mono at 12W but the older ones are not. I would consider buying the used one IF the bi-amp question is clear.
Thanks!
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DBC
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Re: Bi-Amp versus Amp Bridging
Reply #2 - 11/02/14 at 19:42:45
 
Quote:
My question concerns using two identical stereo amps that cannot be bridged to mono, to drive a single speaker each in bi-amp mode.
I assume I would do this by splitting one preamp signal feed (right channel say) and feeding it into both left and right inputs of the stereo amp, then take the left amp out to the "high" binding post on the speaker and take the right amp out to the "low" binding post on the speaker. Removing the gold speaker jumpers of course. Then do the same setup for the other speaker.
Do I have this correct?


You are correct. Using two Amps in this fashion basically doubles your available power which will only increase the output of your old speakers by 3db (not Much IMO).

Rather than spending money on a second amp you may be better off purchasing a used pair of more Efficient speakers (96 to 99 db) if you are concerned about volume output.
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Main System: Oppo BDP-105D, SE84UFO amp, Omega Super Alnico Monitors, Twin Custom SLAB 15's (Low Frequency Open Baffle).
Room #2: Oppo BDP-83SE, SE84CS amp, Omega Super 3i Monitors, Twin Custom SLAB 12's (Low Frequency Open Baffle).
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Core32
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Re: Bi-Amp versus Amp Bridging
Reply #3 - 11/02/14 at 20:29:36
 
So +3dB (doubling) in amp power does not translate to double the audible output, as in RF signal level?
Too old to go back and study my power equations at this point.  ;)
Replacing the speakers, in addition to getting a new amp does not financially compute at the moment I'm afraid.
And I don't normally listen with a ton of volume.
Thanks for the help. It's something I will consider.
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DBC
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Re: Bi-Amp versus Amp Bridging
Reply #4 - 11/02/14 at 20:56:40
 
Each 3db increase in Speaker Volume requires a Doubling of Amp power.

If your speaker is 90db:

1 watt = 90db @ 1 meter
2 watt = 93db
4 watt = 96db
8 watt = 99db

If your room is moderately sized and you listen at moderate levels you are likely to be OK with 6 watts.

As you know if you want more volume there are two choices More Power or More Efficient Speakers. I was just suggesting a used pair of Higher Efficiency Speakers may be less expensive than a second amp (bi-amping).
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Main System: Oppo BDP-105D, SE84UFO amp, Omega Super Alnico Monitors, Twin Custom SLAB 15's (Low Frequency Open Baffle).
Room #2: Oppo BDP-83SE, SE84CS amp, Omega Super 3i Monitors, Twin Custom SLAB 12's (Low Frequency Open Baffle).
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Lin
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Re: Bi-Amp versus Amp Bridging
Reply #5 - 11/04/14 at 02:38:51
 
What speakers do you have?

Passive bi-amping generally does not increase power, you would still have 6w/speaker.
There may be other benefits (or not), but don't count on a 3dB increase of max system output.
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Core32
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Re: Bi-Amp versus Amp Bridging
Reply #6 - 11/05/14 at 00:38:20
 
Can you explain the term "passive bi-amping"?
As opposed to what other type of bi-amping?
Thanks for chiming in.
Still in the decision making stage.  :-/
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Lin
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Re: Bi-Amp versus Amp Bridging
Reply #7 - 11/05/14 at 00:57:46
 
Passive means no electronic x-o before the amps.

What speakers and room size?
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Core32
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Re: Bi-Amp versus Amp Bridging
Reply #8 - 11/05/14 at 02:08:11
 
13' x 20' with a good bit of furniture behind the listening chair.
Left side of room is solid wall. Speakers on one 13' wall. Listening chair about center of the room.
Right side of room has large openings into a parallel 17' x 20' room which has a pool table only.
No audiophile grade speakers so far.
Definitive BP2000s.
Sorry but "means no electronic x-o before the amps".
Do you mean between the driver and the amp? (Internal to the speaker cabinet.)
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Lin
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Re: Bi-Amp versus Amp Bridging
Reply #9 - 11/05/14 at 02:36:03
 
With a powered bass section I think 6 watts should drive them fairly well as long as you don't listen at levels above 90 dB.
Have you ever measured spl when listening?


Preamp > crossover > amp 1 connects directly to tweeters
                             > amp 2 connects directly to woofers

In other words forget about biamping, unless you want to get some measuring equipment (not necessarily a bad thing) and spend a lot more money. Cry
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Core32
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Re: Bi-Amp versus Amp Bridging
Reply #10 - 11/05/14 at 02:53:22
 
I pulled out my old Realistic Sound Level meter a few days ago and replaced the battery. Used it a lot when Home Theater was my thing, to calibrate volume from around the room.
But now the meter doesn't calibrate even close so it's probably old and tired like me Smiley So that will be no help.
Seems like the simpler answer will lie in more efficient speakers IF I am not happy with the level I get from these old monsters.
I do have the bass amps turned to practically nothing, as for music that gives me the best balance frequency wise.
Thanks for all the advice!
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Lin
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Re: Bi-Amp versus Amp Bridging
Reply #11 - 11/05/14 at 03:02:50
 
I currently have an older pair of 90 dB Bostons in a similar sized room with 6 watts (pentode EL84) that does okay.
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Palomino
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Re: Bi-Amp versus Amp Bridging
Reply #12 - 11/06/14 at 21:11:05
 
Fwiw, I have run both 89db and 94db on a Rachael and 89 leaves me wanting more in a 16x12 room.

No real issues with the 94 db.  I do listen a little loud.
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i7 Mac Mini with LPSU/SSD running Audirvana 3.5, Uptone Audio Regen on LPSU, Mytek Brooklyn DAC+, Ven Haus DIY Silver ICs, 25th Ann. Zen, PS Audio P5 Power Supply, PS Audio Power Cords, GR Research Speaker Wire, DIY Big Betsy and Crystal 10 Open Baffle Speakers
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Core32
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Re: Bi-Amp versus Amp Bridging
Reply #13 - 11/07/14 at 00:03:21
 
What's a little loud?
1812 Overture in Symphony Hall loud?
Or front row with Black Sabbath loud?   Cool
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Palomino
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Re: Bi-Amp versus Amp Bridging
Reply #14 - 11/07/14 at 01:43:33
 
90 to 100db
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i7 Mac Mini with LPSU/SSD running Audirvana 3.5, Uptone Audio Regen on LPSU, Mytek Brooklyn DAC+, Ven Haus DIY Silver ICs, 25th Ann. Zen, PS Audio P5 Power Supply, PS Audio Power Cords, GR Research Speaker Wire, DIY Big Betsy and Crystal 10 Open Baffle Speakers
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