Biamping with 2 x identical amps, breakthrough

[Goldjazz]

I've been playing around with biamping my 4343's on and off for months. Ive tried several different amps, a jbl m552 x over and now a berringer one. I was never totally happy with the result, always felt like I gained some bass punch but lost some clarity. Tried inverting woffers etc due to the phase issue of 24db slope but nothing worked. I put it down to poor quality x overs.

Well everything changed last night. I got myself a second Perreaux amp. The first is a 6000b (300w) the second is basically identical a 6200b (270w).

I noticed an immediate improvement on previous biamp attempts. First impressions the 4343s sounded more alive, like they'd been given a shot of adrenalin. The highs are more vivid and the mid bass and lows are more punchy but everything is still clear and tight. Also imaging was better. Basically exactly what I was after.

I feel as though the amps are more balanced and allow the drivers to work together better.

I dont think its the extra power as ive tried a 600w crown with one of the perreauxs before with no good result. Also tried 130w sansui and 130 w accuphase and every combination of those amps above. I dont think its the phase issue with using a 24 db slope either as I tried all the permutations.

I think there's some really good matching or synergy (sorry I hate that word) that happens when you use two identical amps it just sounds balanced and right.

Ive also now got two bgw750c's which are lower power than the Perreaux's. I will try them too and see if this matching thing works with them too.

Is there any basis to this theory? Has anyone else found the same.

Cheers.

[BMWCCA]

I use a Crown PS400 and PS200 which seems to exhibit a similar synergy. Before that I used a Crown DC300A-II and D150A-II. Worked well. Actually I never considered bi-amping with mis-matched amps.

[Goldjazz]

Yeah ok so possibly staying in the same amp brand/family/model range but with different power output still yields the same results as in your case. I'm wondering if matching input sensitivity or gains or something is helping to produce a more balanced result.

I use a Crown PS400 and PS200 which seems to exhibit a similar synergy. Before that I used a Crown DC300A-II and D150A-II. Worked well. Actually I never considered bi-amping with mis-matched amps.

[Odd]

Amplifier for LF and HF work with program material of different frequencies.
Can not see the advantage of using the same brand.
I use a small power Pass Labs Class A on HF and a Crown Power Line Four on LF.
This combination sounds very good.

[loach71]

You have enough amps to go 4-way active. Why not bypass the passive crossovers altogether? I suggest you try a pair of RANE mono 4-way active crossovers. You might be pleasantly surprised. I like the Linkwitz-Riley filter topology used in the RANE product. They are another example of pro gear that is well suited to the home environment.

If you are worried about frying the smaller drivers in your 4343's, you might by a pair of BGW 250D amps for the 10" and compression driver and a BGW 150 for the tweeter. I have enjoyed great success with these amps and they are readily available on E-Pay.

I hope you enjoy experimenting with active filters!

[Goldjazz]

Yep thanks, and I am aware of many people that have good results with mixed amps also, which is why I'm a little puzzled. Perhaps the particular amps I had previous chosen match badly for some reasons whereas the ones you use match well. It's that question of what makes two amps work well together for biamping that I'm interested in.

I'm thinking that some amps differ a lot e.g. input impedence, input sensitivty, gain, or damping factor and it's just harder to find the sweet spot or some other crazy phase shift is going on because of these differences.

Amplifier for LF and HF work with program material of different frequencies.
Can not see the advantage of using the same brand.
I use a small power Pass Labs Class A on HF and a Crown Power Line Four on LF.
This combination sounds very good.

[Goldjazz]

Yeah I've been thinking about it, I need to recap and that would avoid this. But when I was trying to get my head around the passive network that's left when in biamp mode on the 4343 it seems that it's not just a frequency diving network but also doing other stuff which I don't understand yet (e.g. putting delays on certain drivers?) So I'm worried that it just won't sound right i I simply provide each driver with the correct freq band from a separate amp. I know you can put delays in and stuff externally but I think I need to understand what else that network does and how/why it does it....or I could just pull the trigger on those Rane's and start playing around Would love to do this if anyone has had any success, I may put a shout out on technical forum.

You have enough amps to go 4-way active. Why not bypass the passive crossovers altogether? I suggest you try a pair of RANE mono 4-way active crossovers. You might be pleasantly surprised. I like the Linkwitz-Riley filter topology used in the RANE product. They are another example of pro gear that is well suited to the home environment.

If you are worried about frying the smaller drivers in your 4343's, you might by a pair of BGW 250D amps for the 10" and compression driver and a BGW 150 for the tweeter. I have enjoyed great success with these amps and they are readily available on E-Pay.

I hope you enjoy experimenting with active filters!

[loach71]

Yeah I've been thinking about it, I need to recap and that would avoid this. But when I was trying to get my head around the passive network that's left when in biamp mode on the 4343 it seems that it's not just a frequency diving network but also doing other stuff which I don't understand yet (e.g. putting delays on certain drivers?) So I'm worried that it just won't sound right i I simply provide each driver with the correct freq band from a separate amp. I know you can put delays in and stuff externally but I think I need to understand what else that network does and how/why it does it....or I could just pull the trigger on those Rane's and start playing around Would love to do this if anyone has had any success, I may put a shout out on technical forum.

There are many 4th order 4-way active crossovers that incorporate all-pass functions for phase / time delay correction. The RANE gear is of very high quality without the snobbery of "audiophile" equipment and its associated price inflation.

Once done, you can start experimenting with a calibrated mike and a spectrum analyzer such as Room EQ Wizard to see what is really occurring in your sonic environment.

drop me a PM if you want some help...

[badman]

So long as you're not faced with odd time constant or phasing issues (which shouldn't be the case in any decent amps), it's perfectly okay to mix and match amongst good amps. Of course, you then have potential issues with tonal balance etc, but that's what listening is for. Mismatched dynamic performance can also be an issue, so there are several watch-outs, but that's the way of things in general.

[Goldjazz]

Yeah this is tempting. My current active x over (behringer X pro) though pretty low end, is actually capable of 4-way mono. So I could give this a go one speaker. I have intented getting the mike an spectrum anlyzer anyway. Thanks for the offer of help, I will definitely give this a try.

There are many 4th order 4-way active crossovers that incorporate all-pass functions for phase / time delay correction. The RANE gear is of very high quality without the snobbery of "audiophile" equipment and its associated price inflation.

Once done, you can start experimenting with a calibrated mike and a spectrum analyzer such as Room EQ Wizard to see what is really occurring in your sonic environment.

drop me a PM if you want some help...

[Goldjazz]

Speakerdave, yeah I'm interested in understanding what that network is doing for those 3 drivers. Is it mainly EQ'ing to achieve a flat response?

Do you think it would be possible to achieve the same effect through quad amping with an analogue active x over, analysis of the freq response, EQ, and adjusting the gains. I have considered this path with the use of a quality 4-way x over such as an Accuphase f-25, thought the stock freq card options are a bit off for the upper drivers.

Yeah I've been thinking about this conundrum a bit. I definetley want to preserve the passive network untouched, my 43's are basically mint and I want to keep them that way. I was thinking if I did stick with biamping I would build a totally seperate external box probably one of the CC designs others have done here, and just disconnect the original passive network and keep it untouched inside.

ha I don't mind a bit of wildcatting myself, sounds like a nice play with that TAD driver. I am pretty fond of TAD exclusive gear. I've also heard of other's replacing the woofer with a Gauss(brand) 15" driver. I not too much of a JBL fanboy to not consider such things as long as I can always put everything back to factory condition in the end

[antoninus9]

There are many 4th order 4-way active crossovers that incorporate all-pass functions for phase / time delay correction. The RANE gear is of very high quality without the snobbery of "audiophile" equipment and its associated price inflation.

Once done, you can start experimenting with a calibrated mike and a spectrum analyzer such as Room EQ Wizard to see what is really occurring in your sonic environment.

drop me a PM if you want some help...

I agree, Rane is a great choice. I also agree that using two identical amplifiers seems to produce the best results. My guess is that this is related to input sensitivity, and dynamic power output.

[loach71]

I agree, Rane is a great choice. I also agree that using two identical amplifiers seems to produce the best results. My guess is that this is related to input sensitivity, and dynamic power output.

For the purpose of experimentation, a pair of Behringer CX3400s would be OK. That being said, the build quality and sonic performance of the Behringer products in no way reaches that of the RANE active crossovers.

In short, you get what you pay for.

[Goldjazz]

For the purpose of experimentation, a pair of Behringer CX3400s would be OK. That being said, the build quality and sonic performance of the Behringer products in no way reaches that of the RANE active crossovers.

In short, you get what you pay for.

Yeah I totally agree Behringer is not good. I just got it as I wanted to play around. Having said that, I am getting better results with the Behringer than the JBL M552 I have.

[audiomagnate]

I don't think "indenticalness" for lack of a better word, helps in itself at all. Why is it a good thing for a tweeter amp to be identical to a woofer amp? Not only does it not provide an inherent benefit, it's a huge waste of money. Amps best suited to the frequency range in which they are operating is a much better way to go. It's bad enough finding room for multiple amps, but then adding the requirement that they all have to have the same current delivery potential as the ones on the woofers, meaning they all have to be huge and use all sorts of electricity, is just wrong. It's nice when things match, but it makes zero sense in this situation.