[Sasha]

James,

Could you please give me your thoughts on the following?
Is it a good idea to consider two different amps from two different manufacturers for bi-amping?
Is the gain matching the only factor to consider?
If I get a Bryston pro version with gain control so that Bryston’s gain can be matched to the gain of the other amp that is not adjustable, did I cover all the bases?
Are there other factors to consider, for example phase of the signal? Can it be assumed that phase will match or anyting goes?
Is there a way to measure parameters that impact suitability of two different amplifiers for bi-amping amplification?

Thanks,
Sasha

[James Tanner]

James,

Could you please give me your thoughts on the following?
Is it a good idea to consider two different amps from two different manufacturers for bi-amping?
Is the gain matching the only factor to consider?
If I get a Bryston pro version with gain control so that Bryston’s gain can be matched to the gain of the other amp that is not adjustable, did I cover all the bases?
Are there other factors to consider, for example phase of the signal? Can it be assumed that phase will match or anyting goes?
Is there a way to measure parameters that impact suitability of two different amplifiers for bi-amping amplification?

Thanks,
Sasha

Hi Sasha,

The gain is the most critical of course because of the inability to adjust gain in the Passive crossover of the speaker. The gain control on the Bryston only allows you to 'reduce' the gain so as long as the other amplifier has lower gain than the Bryston you are OK.

The amplifiers may or may not 'invert'- phase - All Bryston amps have positive phase (positive signal in gives a positive signal out). So make sure you know if the second amp inverts phase. You can still use the amp but the speaker cables would have to be inverted.

The engineering types will tell you that all should be good if the phase and gains are aligned but I have always found the same manufacturers amps sound better than mixed manufacturers.

[Sasha]

James,

Thank you for your input.
Would you mind giving me your opinion on my dilemma?
Presently I have FB1+ driven by 2X50W amp in class A.
I am perfectly happy with this combination with exception of lower end performance.
I have not heard an amp that does better midrange with PMC then my amp, but it does not have enough muscle to do lower octaves correctly.
And I have not heard an amp that does better job in low end then Bryston.
So I was thinking of getting OB-1 where 4B pro would drive LF, and my amp MF and HF drivers.

The other alternative is to keep FB1+ and get an active sub (TLE1 comes to mind).
In this case how do I properly cross from TLE1 to my amp driving FB1+?
Does TLE1 come with some sort of active crossover?
If not, I understand Bryston makes one?
Can this be done?
Does this option make more sense then the first one with OB-1 being driven by 4B pro and my amp?
Is it true it is extremely difficult to properly and seamlessly integrate sub with two-way speakers in 2 channel system, so that the LF does not sound detached from the rest?

[James Tanner]

James,

Thank you for your input.
Would you mind giving me your opinion on my dilemma?
Presently I have FB1+ driven by 2X50W amp in class A.
I am perfectly happy with this combination with exception of lower end performance.
I have not heard an amp that does better midrange with PMC then my amp, but it does not have enough muscle to do lower octaves correctly.
And I have not heard an amp that does better job in low end then Bryston.
So I was thinking of getting OB-1 where 4B pro would drive LF, and my amp MF and HF drivers.

The other alternative is to keep FB1+ and get an active sub (TLE1 comes to mind).
In this case how do I properly cross from TLE1 to my amp driving FB1+?
Does TLE1 come with some sort of active crossover?
If not, I understand Bryston makes one?
Can this be done?
Does this option make more sense then the first one with OB-1 being driven by 4B pro and my amp?
Is it true it is extremely difficult to properly and seamlessly integrate sub with two-way speakers in 2 channel system, so that the LF does not sound detached from the rest?

Hi Sasha,

You got it! - Subwoofer integration is the MOST difficult assignment there is.

The TLE has a Bryston amp built in but there is no crossover as the TLE is designed to run in tandom with the Mains, with the Mains running fullrange. So using a sub with the 10B Electronic crossover will definitely give you a lot more flexibility in integrating the Sub. The 10B allows you to adjust both the crossover point and the slope on both the hi-pass and the low-pass sections. If you can get the Sub integrated properly there is a lot to be said for this type of configuration. The Mains can be placed for best imaging and spaciousness while the Sub can be used in the best location for flat and deep bass response.

The other option, as you suggest, is to go to the bigger speaker and Passively Bi-amp which as I said in my other post is do-able as long as you take phase and gain into account.

I think if you are getting a good image and soundstage with good bass response with the FB1's in the location they are in now in your room go with the bigger OB1. If the bass response is not all that great the Sub/Mains/10B option may work better.

james

[Sasha]

Thank you James.

I compared specs for bi-amping application, it looks feasible?
My amp:
Input impedance 53.3 Kohms
Output impedance 0.016 Ohms
Input sensitivity RCA inputs 0.7 Volts Rms for max power
Input sensitivity Balanced inputs 0.35 Volts Rms for max power
4B SST:
Input impedance 50 Kohms single ended
Input sensitivity 1.8Vin – so the Pro version can be lowered and thus equal the lower input sensitivity of the other amp?
Or I am not talking the right language here, lowering input sensitivity actually means more volts required at input for max power, meaning I can adjust Bryston to be higher then 1.8V, not lower?