Bi-amping the Heathkit AS-103/103A speaker system

[dynaco_dan]

Hi there;

I have not practiced bi or tri amping speakers at all.

Heathkit mentioned bi-amping in their manuals for both the AS-103/103A speaker kit systems.

This of course was the two AR-3A equivalent speaker systems, most parts of which were provided by AR.

No drawing or written instruction's were given, just the comment.

I do not remember AR ever commenting, suggesting or instructing owners how to do it.

A very serious problem would be if the amps two hots were wired incorrectly.

With the ability to isolate the woofer and mid/tweeters, by removing the jumper, this is a possible option for driving them.

[onplane]

Hi there;

I have not practiced bi or tri amping speakers at all.

Heathkit mentioned bi-amping in their manuals for both the AS-103/103A speaker kit systems.

No drawing or written instruction's were given, just the comment.

A very serious problem would be if the amps two hots were wired incorrectly.

With the ability to isolate the woofer and mid/tweeters, by removing the jumper, this is a possible option for driving them.

The correct way to bi-amp would be to add a 4th terminal and completely isolate the woofer from the mids/tweeters. Naturally, to return to a single amp, you would then add two straps as opposed to one.

This scheme solves the problem of the "hot leads" on independent amps.

Saying this, however, is NOT what I do. I bi-amp using the three stock terminals. My amps are both solid state common ground and I wire the grounds together on terminal "1". Terminal "2" becomes the hot lead for the amp powering the woofer. Teminal "T" then becomes the hot lead for the amp powering the mids/tweeters.

My setup:

170 wpc (rms measured @ 4 ohms) for the woofer

30 wpc (rms measured @ 4 ohms) for the mids/tweeters

Each amp is integrated and has it's own volume control and that gives me control over the amount of power going to each half of the speaker. I further turn the treble control full off on the woofer amp and the base control at minus 5db on the mid/tweeter amp.

Hope this helps ...

Regards,

Jerry

[rrcrain]

The correct way to bi-amp would be to add a 4th terminal and completely isolate the woofer from the mids/tweeters. Naturally, to return to a single amp, you would then add two straps as opposed to one.

This scheme solves the problem of the "hot leads" on independent amps.

Saying this, however, is NOT what I do. I bi-amp using the three stock terminals. My amps are both solid state common ground and I wire the grounds together on terminal "1". Terminal "2" becomes the hot lead for the amp powering the woofer. Teminal "T" then becomes the hot lead for the amp powering the mids/tweeters.

My setup:

170 wpc (rms measured @ 4 ohms) for the woofer

30 wpc (rms measured @ 4 ohms) for the mids/tweeters

Each amp is integrated and has it's own volume control and that gives me control over the amount of power going to each half of the speaker. I further turn the treble control full off on the woofer amp and the base control at minus 5db on the mid/tweeter amp.

Hope this helps ...

Regards,

Jerry

I'm biamping using two rack mounted Heathkit AA-1800 amps. These amps have speaker common connected to chasis ground making the speaker commons between amps internally connected when rack mounted. I cringe on the 3 post biamping but also realize I'm effectively doing the same thing but on the other end of the speaker wire.

Richard

[onplane]

I'm biamping using two rack mounted Heathkit AA-1800 amps. These amps have speaker common connected to chasis ground making the speaker commons between amps internally connected when rack mounted. I cringe on the 3 post biamping but also realize I'm effectively doing the same thing but on the other end of the speaker wire.

Richard

Hi Richard!

Actually, the grounds on my amps are connected together via the shielding on the audio cables as well as terminal "1".

In addition, I added another strap (very short piece of lamp cord) between the amps that shunts the speaker ground connections.

You mentioned a long time ago your fear of having a potential difference between terminal 1 on the AR's and the amp grounds. As a result of your comment, Richard, I added that lamp cord strap.

Like you, I don't trust the shielded cable and we certainly do not want any potential difference between the amp grounds and terminal 1.

Regards,

Jerry

PS: I'm still amazed at the difference in the impedance of the AR-3a intact and the impedance of just the woofer (including its cap and coil):