biamping with a arc 150.2 and vtl mb125

The output won't always be even between the amps. You may have too much bass when quiet listening and too little bass at high volumes or the reverse. You really should have matching amps to do this (it can't hurt to try).

i wish i had the option op trying it first, i do not.. so i am hoping to get feedback before i make a mistake
thanks

Hi Sy,

I recall from your other thread a couple of months ago that you are using Ascendo C7 speakers. I wasn't able to find detailed information about their impedance vs. frequency characteristics, just that they have a nominal impedance rating of 6 ohms.

The VTL amp has a specified output impedance of 1.6 ohms, which is high to the extent that I would expect its sonic character to vary significantly as a function of the impedance vs. frequency characteristics of the particular speaker. Therefore I don't think it is possible to predict how well its sonic character will match that of the ARC amp without experience using those amps on your particular speakers.

Also, according to my calculations there is likely to be a gain mismatch of a few db between the two amps, in the direction of the gain of the VTL's being greater. Especially if they are used in the higher powered tetrode mode.

Best regards,
-- Al

thanks al. i was told by arc that if i used balanced cables for the arc and rcas for the vtls the power would be closer.. am i wrong on that?

Hi Sy,

That could be true, but I'm not sure.

Everything else being equal, a balanced interface will provide 6db greater gain than an unbalanced one, because the balanced input responds to the difference between two equal and opposite signal polarities, rather than to the difference between one of those polarities and ground (0 volts).

However, I'm not sure if that fact is or is not already "built into" the spec for the 150.2 which indicates identical 1.4 volt sensitivity and 27 db gain numbers for both the balanced and unbalanced inputs.

Best regards,
-- Al

al,
iain am xompletetly clueless when it comes to this. with your best judgement, do you think i should try it?
thanks ag

Hi Sy,

My instinct would be "no," given that you don't have a means of trying it out which is both convenient and without obligation. There are too many variables, unknowns, and causes for concern.

I would suggest not bi-amping and simply buying a more powerful amplifier, and waiting however long it takes to find a buyer for the VTL's. At only $1600 a buyer certainly figures to be forthcoming eventually.

Best regards,
-- Al

You could try inline attenuators to balance the gain but, fair warning, those tend to have quite low Zin themselves. Then, you have an impedance matching issue. Also, the more complicated the system gets, the more likely to get ground loops.

Ask the manufacturer of the preamp or source (if direct) if it advisable to use both RCA and XLR outputs simultaneously.

What's the crossover point? What speakers?

There are tube amps with good bass but is that the best option for bass only?

You could try inline attenuators to balance the gain but, fair warning, those tend to have quite low Zin themselves. Then, you could have an impedance matching issue. Also, the more complicated the system gets, the more likely to get ground loops.

Ask the manufacturer of the preamp or source (if direct) if it advisable to use both RCA and XLR outputs simultaneously.

What's the crossover point? What speakers?

There are tube amps with good bass but is that the best option for bass only?

thanks guys, all your proffessional input makes my life easier. Al, i will take your advice and not try it..ill wait and see if i sell my vtlS
ngjockey, the speakers are ascendo c7,i do not know what the crossover points are..
thanks all
sy