Biamping with a single Balanced connection

ec · « **on:** 26 Jul 2003, 01:37 am »

I have the SP 1.7 and using PMC TB2 speakers. The amps are not Bryston ..... yet.

I am beginning to experiment with "vertical" biamping the PMC's. Currently, I can easily hookup my current amps and future Bryston amps via RCA and a splitter. When I do upgrade my amps to Brystons I would like to experiment with biamping but is this possible using a balanced XLR connection? I want to use XLR because one set of amps will be about 40' away via cabling and I like the noise rejection of balanced inputs. Ultimately I would like to send a balanced XLR (or 1/4" headphone type connector) connection from the SP 1.7 to say one 3B or 4B and have it output the same signal to both channels on the amp.

Once I finish experimenting with biamping on my current Acurus amps I may not notice a difference and thus forgo this whole thing. But if I feel biamping is worthwhile I would like to do this on Bryston amps but using a balanced connection. I have seen some other manufacturers have circutry to accomodate this.

James Tanner · « **Reply #1 on:** 28 Jul 2003, 02:55 am »

Hi Eric,

Yes you can use a Y balaned connector.

james

ec · « **Reply #2 on:** 28 Jul 2003, 03:13 am »

James,

Thanks for all your assistance in answering our questions. Now I just got to find a bunch of these Y balanced connections and three to five 4B SST's

jethro · « **Reply #3 on:** 13 Aug 2003, 04:18 pm »

Is it a general rule that when bi-amping (or tri-amping), that the two (or three) separate sections of the crossover individually present the same power to their respective drivers as when single-amping ?

In particular, I am looking at biamping my IB1's with two 4B-STs or a 4B-ST and a 3B-ST. My amps are all pro models so I can tweak levels if the different sections of the crossover require different power levels.

Thanks.

James Tanner · « **Reply #4 on:** 13 Aug 2003, 11:32 pm »

Hi Jethro,

The passive crossover limits the frequency response to the specific driver.
The power requirement will differ depending on the driver. A tweeter requires far less power than the woofer.
When you "passively" biamp it is important that the amplifiers have equal "gain" - they can have different power levels but they must have equal gain.
All Bryston ST and SST amps have the same gain regardless of power - so you can use 2 - 4B ST's or mix a 3B ST and a 4B ST.

james

nicolasb · « **Reply #5 on:** 14 Aug 2003, 09:32 am »

Quote

A tweeter requires far less power than the woofer.
...
All Bryston ST and SST amps have the same gain regardless of power - so you can use 2 - 4B ST's or mix a 3B ST and a 4B ST.

Would that imply that if you are bi-amping two speakers then using a 4B amp for both bass drivers and a 3B amp for both tweeters is likely to sound as good as using a pair of 4Bs, or is the difference between 4B and 3B models much more than a question of power output?

James Tanner · « **Reply #6 on:** 14 Aug 2003, 11:34 am »

Hi nicolasb,

Unless the drivers require the power I would tend to use the smaller amp on the tweeter. Usually 'less is more' and the 4B would be wasted on a tweeter.
In 3- way speakers where you have the option - like the IB1 - where you can drive the mid/tweeter and the woofer separately then similar amplifiers would make sense.
let me remeind you that 'passive biamping' is a much different issue than 'active biamping' and a lot of the advantages of active biamping do not apply to passive biamping.

james

nicolasb · « **Reply #7 on:** 14 Aug 2003, 12:21 pm »

Okay, so using different amps to drive a bi-ampable three-way speaker (bass on one set of terminals, treble and mid-range on the other) wouldn't be such a good idea?

This is actually of some practical interest to me at the moment: my B&W Nautilus 803s - 3-way design as described above - are bi-ampable, and I've been wondering whether it would be best to single-amp them with my 4B-ST, or bi-amp using 4B-ST for the bass drivers and a pair of channels from my 9B-ST for the tweeter/mid-range.

James Tanner · « **Reply #8 on:** 14 Aug 2003, 12:54 pm »

Hi,

Usually you are better served with a single 'larger' amp driving the whole passive speaker. So if you were purchasing amplifiers you are better off with a single 4B rather than 2-3B's.
If you have an amp available to use on the tweeters mids tweeter it certainly will not hurt but I just want to inform you that the differences will not be great.

james

nicolasb · « **Reply #9 on:** 14 Aug 2003, 03:11 pm »

The eventual plan is to go to 7.1, but as that's in the future a bit I'm considering experimenting with the spare amplifier channels in the mean time. So the question is whether bi-amping with 4B (bass) and 9B (treble and midrange) is likely to be an improvement over single-amping with the 4B. I'll have to ask the B&W people what they think....

jethro · « **Reply #10 on:** 15 Aug 2003, 01:40 am »

Quote from: James Tanner

Hi,

Usually you are better served with a single 'larger' amp driving the whole passive speaker. So if you were purchasing amplifiers you are better off with a single 4B rather than 2-3B's.
If you have an amp available to use on the tweeters mids tweeter it certainly will not hurt but I just want to inform you that the differences will not be great.

james

I'm no audio expert, but my previous experiments with bi-amping agree with James' comments. I have tinkered with passively bi-amping B&W 604S2's using an 8B-ST. I found it was better than single-amping with a 3B-ST - there seemed to be less distortion at higher levels. I had a 4B-ST in the closet that I had never used because I felt the 3B-ST and 8B-ST should have more than enough power. One day I figured that I should at least connect it up to make sure that it worked since I had bought it used. I didn't like the 4B-ST at first because it seemed to roll-off the high-end compared to the 3B-ST. The 4B-ST did have a lot more bass though. After talking to James, I realized that the frequency response of the 4B-St was smoother than the 3B-ST so the high frequencies of the 3B-ST were actually more apparent because of a poorer frequency response at low frequencies. To sum up, I like the 4B-ST a lot more than the 3B-ST.

I've since done single-amping tests between the 3B-St, 4B-ST, Citation 5.1, Citation 7.1 amps, and B&W 604s2's, B&W 600s3's, B&W 601S2, and PMC IB1's. I always preferred the sound of the 4B-ST. I can't explain why because I don't know the audio lingo (bought my first stereo 3.5 years ago). It just sounds better to me.

Sometime in the near future (meaning hopefully before xmas), I still intend to try bi-amping/tri-amping my IB1's with various combinations. I imagine that I will probably eventually go with a pair of 7B-ST's (single-amping) for my IB1's, however experimenting is fun. If the difference (to my ears) between the 4B-St and the 3B-St, is as good as the difference between the 4B-ST and the 7B-ST, then it will be well worth it.

editted August 20, 2003

changed:

"Is anybody else out there using 7B-ST/SST or 14B-ST/SST with their PMC IB1's ?"

to:

Is anybody using 7B-ST/SST or 14B-ST/SST amps with their PMC IB1's ?

Paul L · « **Reply #11 on:** 18 Aug 2003, 08:34 am »

I don't think it is a matter of 'large' amp. But I think a 'higher quality' amp to drive the complete speakers is better than using two 'so-so' amps to do bi-amping.

James Tanner · « **Reply #12 on:** 18 Aug 2003, 12:16 pm »

Hi Paul,

No, my point was that there is not much of a benifit when you "Passively" bi-amp. You are much better off with a bigger version of the same amplifier than 2- smaller versions.
Because you have to still use the Passive crossover built into the speaker you do not have the same benifits of lower distortion and increased dynamic range that you get with an "Active" crossover.

james

nicolasb · « **Reply #13 on:** 18 Aug 2003, 01:02 pm »

Quote

a 'higher quality' amp to drive the complete speakers is better than using two 'so-so' amps to do bi-amping.

Yes. But this still doesn't really address the question of whether a 4B and a 3B together (4B driving the bass, 3B midrange and tweeters) is likely to sound better or worse than the 4B by itself (driving everything).

Paul L · « **Reply #14 on:** 18 Aug 2003, 06:10 pm »

It will not be worse for sure. However, how much improvement depends on how dificult your speaker load is. The more difficult the load, the more improvement it will be.

Paul Lam
P.L.C.Lam Consulting Inc.

James Tanner · « **Reply #15 on:** 19 Aug 2003, 11:49 pm »

Hi Paul,

I agree - if the woofer is creating a difficult load for the bass amplifier then having an independent amplifier driving the mid/tweeter will certainly help - but getting a single bigger more competent amp based on the load requirement also solves the problem.
There is one area were passive biamping can be usful and that is if you have a particular amp you like for bass and a different one for mid/tweets.
The only issue there is to make sure both amps have the same 'gain' - otherwise you will have an imbalance in the response of the speaker.

james

jethro · « **Reply #16 on:** 20 Aug 2003, 01:59 pm »

Generally speaking,

Does the use of an external line-level crossover (like a 10B) in combination with the speaker's built-in crossover in a bi-amping setup have any effect on the sound? i.e. Does limiting the range of frequencies input'd into a driver's crossover help the crossover work better ?

James Tanner · « **Reply #17 on:** 20 Aug 2003, 03:19 pm »

Hi,

You can not use an active crossover in series with the passive crossover in the speaker. The crossover in the speaker at the crossover point should have flat amplitude - if you insert another electronic crossover in front of the passive crossover you will end up with either a dip or peak through the crossover region.
The 10B is fine if you are adding a subwoofer to an existing speaker and want to integrate the speaker with the sub or if you can bypass the speakers internal passive crossover.

james