Will my AR3a bi-amp set-up work?

[Guest fwardell]

I've been searching this and other forums on how to bi-amp my AR3as which are currently driven by a Fisher 500-C. My proposal is to use a NHT MA-1A (or perhaps 2A) amp to drive the woofers. A proposed wiring schematic is included. The thing I like about the MA-1A is that it's designed for driving subwoofers and it has a crossover network for the highs and mids. Of course, it's mono, but that shouldn't hurt the bass, right? I'm thinking that running the Fisher speaker outputs through the MA-1A will have all negative outputs at the same ground which the AR3a would like. The BIG question: will this work well? Secondary question: should the MA-1A Bypass Switch be on or off?

AR3a_Fisher_Bi_amp_Diagram.doc

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I've been searching this and other forums on how to bi-amp my AR3as which are currently driven by a Fisher 500-C. My proposal is to use a NHT MA-1A (or perhaps 2A) amp to drive the woofers. A proposed wiring schematic is included. The thing I like about the MA-1A is that it's designed for driving subwoofers and it has a crossover network for the highs and mids. Of course, it's mono, but that shouldn't hurt the bass, right? I'm thinking that running the Fisher speaker outputs through the MA-1A will have all negative outputs at the same ground which the AR3a would like. The BIG question: will this work well? Secondary question: should the MA-1A Bypass Switch be on or off?

Nope, your proposed diagram will NOT work and will most likely ... harm the amp. Don't hook it up the way you have drawn it UNLESS ... you like to see that magic white smoke.

Yes, mono will hurt the bass, because the woofers in your AR's are NOT sub woofers. Then hooking them in parallel will create a load of 2 ohms on your amp. Further, the AR woofers provide sound up to and beyond 1,000Hz and no sub-amp will feed them signal this high.

A plate amp or sub-woofer amp is NOT going to work. The AR-3a woofers need a full range amp event through they are not full range drivers.

Next running the Fisher speaker outputs into another amp is a really, really bad idea. All you are doing is increasing the signal path and insuring the maximum amount of distortion is present at the speakers.

If you really want to bi-amp and use your Fisher, it can be done, but you must be very careful as the wiring is NOT standard. Further, you'll need a full range STEREO amp for the woofers. Minimum power on that amp would be 50 wpc rms measured 4 ohms or higher.

There are tons of those amps around and they are cheap. If you get your hands on one and want to bi-amp send me a PM (private message) and I'll give you the directions on both testing and hooking this up.

Example of a 100 wpc amp

Regards,

Jerry

[Guest fwardell]

Thanks - read you loud and clear - no white smoke! I'm wanting to stay vintage - and tube if possible - perhaps Dynaco ST-70 (tube) or ST-120 (SS). Those work you think?

Nope, your proposed diagram will NOT work and will most likely ... harm the amp. Don't hook it up the way you have drawn it UNLESS ... you like to see that magic white smoke.

Yes, mono will hurt the bass, because the woofers in your AR's are NOT sub woofers. Then hooking them in parallel will create a load of 2 ohms on your amp. Further, the AR woofers provide sound up to and beyond 1,000Hz and no sub-amp will feed them signal this high.

A plate amp or sub-woofer amp is NOT going to work. The AR-3a woofers need a full range amp event through they are not full range drivers.

Next running the Fisher speaker outputs into another amp is a really, really bad idea. All you are doing is increasing the signal path and insuring the maximum amount of distortion is present at the speakers.

If you really want to bi-amp and use your Fisher, it can be done, but you must be very careful as the wiring is NOT standard. Further, you'll need a full range STEREO amp for the woofers. Minimum power on that amp would be 50 wpc rms measured 4 ohms or higher.

There are tons of those amps around and they are cheap. If you get your hands on one and want to bi-amp send me a PM (private message) and I'll give you the directions on both testing and hooking this up.

Example of a 100 wpc amp

Regards,

Jerry

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Thanks - read you loud and clear - no white smoke! I'm wanting to stay vintage - and tube if possible - perhaps Dynaco ST-70 (tube) or ST-120 (SS). Those work you think?

The Dynaco ST-70 will NOT work with the three terminal bi-amp, because it's input "floats" above ground potential. Now, if you bring out a 4th terminal on your AR's (like Shacky did) any two amps will work. With three terminals, we have to be careful because we tie all of the amp grounds together.

The Dynaco ST 120 will work, but it's not as flexible as an integrated amp. If you want to "stay vintage", I'd recommend the AR amp.

This way if you decide bi-amping is too much of a hassle, then you have an amp fully capable of powering your AR's all by itself. If you can't find an AR, then look for a vintage ss integrated amp as these are just easier to deal with, plus they'll do a better job on the deep bass than a tube set.

Regards,

Jerry

[Guest fwardell]

Well, I chickened out using the Fisher 500-C and another amp to bi-amp the AR-3As. Just too scary - fear of white smoke! Decided to acquire a vintage SS Dynaco set-up (PAT-4, ST-120 & FM-5) piece at a time to drive the ARs. Recall reading that's a good match, plus they have a good rep. Am looking at a pair of Dynaco A-25s for the 500-C.