testing a crossover

millercarbon

You have a dead short. They worked when connected normally because then the amp sees the sum total resistance including the 6.8-7.9 ohms. But connected bi-wire one amp sees only a dead short and so pop, there she goes.

Nope. You're confusing bi-wire with biamplification. They are two different things.
In biwire configuration, the amplifier still sees the drivers' total resistance.

Okay so MC said bi-wire and not bi-amp, big deal, I knew what he meant. At this point we know there's a short somewhere. Could be shorted caps, but we need more info.

Where the heck is George at?

You use a single amp and it works with a little less bass. "lack of bass and tightness". NOT no bass. If all the drivers are working and you run the XO in parallel, the reading will go LOWER not higher. Parallel a pair of 8 ohm speakers you get 4 ohms.

Put your DMM on the post that reads ZERO and leave it there for a a while. You have to charge the cap (s) with YOUR little battery in the DMM, do you understand? A lot more caps in the band pass than the BASS OX.

On the bass side there is usually just a low pass, a resistor for 6 db first order maybe a cap TOO, for a second order 12db..

Get some correct data FIRST then figure out what up.. I’m not 100% sure until I know what the mids and highs read on a DMM.

Going from bi-amping to bi-wiring and a single amp tells me there is an AMP problem or the way it’s being wired. A stray single strand or some weird thing like that.. A close look and make sure there is no stray wires touching and you somehow make that happen when you hook that amp back in. You don’t want a strand from one amp touching another.

IF the same speaker cables are being used and you're just adding or removing an amp, it sure sounds like an amp issue to me.

Less swapping a PC for the one that keeps taking a dump.. You did swap PC right? What else is there?

Check the RCAs and XLRs cables for the amp that is acting up. Just swap the silly things.. make sure.

Regards

The formula for parallel resistance is 1/Rt= 1/R1+1/R2+1/R3....   
https://www.electronics-notes.com/articles/basic_concepts/resistance/resistors-in-series-parallel.ph...

Since he measured almost 8 ohms then the total resistance will be 1/8 ohm + 0 ohm or 0.125ohm.  

I think we all can agree that is a pretty low resistance and would suck the bass and dynamics out of most amps. 

What I don't understand is where is the short? And how does the driver manage to still get enough signal to make sound even though there is a dead short?

Got me MC. I think the repair guy missed something.. If it was to heavy a load it will pop a fuse not blow up. Must have one sorry protection circuit.

TWICE. I don’t think so.. It’s the amp or PC or RCA or something exclusive to THAT amp..

The input to the amp?

It should pop a fuse if it’s on the output side, like a speaker issues, usually.

All I know is neg to neg and pos to pos = 1/2 the two numbers added together. 8 ohm top + 6 ohm bottom = 14 ohms /2 = 7 ohms

Running neg to pos, to neg to pos, combines the two. 6 ohm bottom + 8 ohm top = 14 ohms.

8 -14 ohms loads on my valve amps are just perfect. They run a LOT cooler and clear as a bell all the way to 100% volume..

I’m likin’ the bass at 8-12 ohms better too, with BIG class d amps. They are 12K amps. 1700 x 2 all day long at 12 ohms bullet proof. Dirt cheap!

Get a Behringer NU12000 (NO DSP) move your other amp to the top. Be happy for 400.00 and 10 years.. I disconnect two of the 3 fans and put the last one on a switch. Perfect.. DEAD quiet.. or hook it to 10-12 18" subs.. It will push EVERY one to 120 db.

I'm thinkin' 4 new 21" Dayton's with 8 18" passives would be a good bass system .. :-) I like a room that can tenderize meat in a pinch.. :-)