Bi-Amping with Arcam Alpha 6 possible?

[Philip A.]

Hi,
I have already Bi-wired my system (Arcam Alpha 6 + JM-Lab Profil 5B Speakers) for over a few years now, with succes.
I would like to improve the sound by buying a second Alpha 6 amp to create a Bi-amping system.
Does anybody know how this is done with The Alpha 6?
Thanks for your help.
Philip A.

[lucpes]

There's no specific recipe for various amp/speaker combos. You should have searched on Google:

http://www.whathifi.com/newsMainTemp...ewssectionID=3

http://sound.westhost.com/bi-amp.htm

[Bill Fitzpatrick]

Does your bi-amping desire include an electronic crossover?

[Philip A.]

Both the alpha 6's are identical integrated amplifiers without preout sockets.
I would like to know how to adjust the Alpha's so I can use them in an Bi-amp situation.
The integrated amp and the power amp must be connected together with a stereo pair of interconnect cables, pre-out on the integrated to pre-in on the power amp.
You then use one (intgrated) amplifier to drive the left and right treble (or high frequencies), and the other to power the left and right bass. In general terms, the integrated drives the treble, and the power amp the bass.

[Bill Fitzpatrick]

Use a "Y" connector having 3 RCA males. One goes to pre-out and the others to the power amp ins.

If you do this though, the amp for the tweeters will be running without a load at the low frequencies and the amp for the woofers will be running without a load for the high frequencies. Your amps may not be happy about this.

[5th element]

Ok but I think the basic problem here is that the 6's dont have either pre out or ins and Philip is asking how to either connect them because of this, or how to modify the amps so that they do!

Well the simplest approach is use the tape loop of the first amp and simply hook the outs to a line in on the second amp. Ofcourse this means you have to adjust both volume controls but appart from that this setup works well. Its also worth considering using one integrated for the left channel and one for the right. This way the stress on the power supply in the amps is equally split, giving each amp roughly the same thing to amplify. For instance one amp on two bass drivers is going to work harder then the one on the tweets so thus will stress the power supply more. So using one per chan means the bass amp would work less hard bu the tweets would work harder, but the overall effect should be better.

If you want to go down the route of modding the amp I dont think it would be particularly hard. I did this with an old musical fidelity A1 integrated. All you need to really do is locate where the preamp ends and the power amp starts, then simply run wires from these points to phonos on the chassis.

Another thought is Arcam themselves, if you dont want to get your hands dirty let them do it for you. They used to have a service that did the very thing you are after add preouts to the 6's to enable bi amps with 7's 8's 9's and ten power amps. If all they have is adding preouts then you could take the preouts into a line in on the second 6 then simply adjust the level of the second amp to your liking, then control the volume from the first amp.

Matt

[Bill Fitzpatrick]

Hmm. Seems that I misread about his have pre-out amp-in connections.

Anyway, I don't see that there is going to be anything gained. I don't believe that bi-wiring offers an improvement let alone bi-amping in this manner.

What's your take on running amps with only partial loads?

[planet10]

Originally posted by Philip A.
Both the alpha 6's are identical integrated amplifiers without preout sockets.
I would like to know how to adjust the Alpha's so I can use them in an Bi-amp situation.
The integrated amp and the power amp must be connected together with a stereo pair of interconnect cables, pre-out on the integrated to pre-in on the power amp.
You then use one (intgrated) amplifier to drive the left and right treble (or high frequencies), and the other to power the left and right bass. In general terms, the integrated drives the treble, and the power amp the bass.

If the 1st sentence is correct the rest of it doesn't make sense...

You need to be able to get at the pre & power sections separately... so if this is an ingegrated without pre-out, power-in, then step one is to add them...

then if passive bi-amping (which will gain you a bit), using the pre in one you drive both the poweramps. With 2 power amps the same, you would use one to drive each speaker (ie L to drive the bass, R to drive the treble) -- this maximizes available power supply since the bass channel usually requires the most juice. In your case since the pre is using the same power supply (unless the Arcam has separate supplies for the pre & power) you might find that the pre sounds better if its amp is only driving the treble.

If active bi-amping (this is where the big improvements come), you drive an active XO with the pre, and the power-amps are driven by the XO. You need to remove the passive XOs in the speaker. To get it right you may need to emulate any EQ in the passiveXOs in the activeXOs.

dave

[sreten]

Another option is semi active operation.

Instead of using two similar power amplifiers you use a smaller
one for the treble, the gain needs to be adjusted to be equal
to the gain of the bass amplifier.

By adding a simple first order high pass filter, say at 500Hz,
this is how you can easily use a smaller amplifier for treble.
(For clipping reasons this is a good idea
even if the power amplifiers are the same)

The speakers passive crossovers are still used.

Adding a first order low pass to the bass amplifier well above
the c/o frequency doesn't gain much at all, so not worth doing.

The treble amplifier output needs to be tapped off the main
amplifiers power amplifier inputs.

sreten.

[5th element]

I said exactly what plannet said?