amps blow fuses when connected to my omegas.

bakufu · « **on:** 22 Apr 2022, 03:08 pm »

i have a technical question. i'm hoping someone in this group can provide an answer.

i've been running a pair of ampzilla 2000 second edition monoblocks for more than a decade. these amps are rated at 300w into 8 ohms.

in that time i've used them to drive a variety of speakers. for the last 2 years i've used them successfully with a pair of ohm f5's with a sensitivity of 88db.

the other day i tried hooking them up to my super alnico high output XRS, rated at 97db.

immediately on powering up the ampzillas, fuses blew on both amps. this is the first time i've blown a fuse on either amplifier.

can anyone tell me what's going on here?

pstrisik · « **Reply #1 on:** 22 Apr 2022, 05:01 pm »

Curious. Two separate amps blew fuses at the same time and, I assume, you have used the Omegas with another amp without problem. So far, the logical conclusion is some kind of incompatibility, though I've never heard of this before.

audiomaniac · « **Reply #2 on:** 22 Apr 2022, 05:21 pm »

With 300 watt mono blocks, I would think it would have been the speakers that would have blown.

bakufu · « **Reply #3 on:** 22 Apr 2022, 08:09 pm »

i'll add that the amps appear to be fine - i've since re-connected them to my ohms without any issues.

seikosha · « **Reply #4 on:** 22 Apr 2022, 08:45 pm »

Have you tried other amps with the Omegas?

Woodsage · « **Reply #5 on:** 22 Apr 2022, 09:06 pm »

I wonder if the high power, high current amps are seeing the crossover-less Omegas as a direct short?

FullRangeMan · « **Reply #6 on:** 22 Apr 2022, 10:19 pm »

Quote from: Woodsage on 22 Apr 2022, 09:06 pm

I wonder if the high power, high current amps are seeing the crossover-less Omegas as a direct short?

Unlikely they are 4-6Ω, short circuit are under 3/4Ω for regular amps.

bakufu · « **Reply #7 on:** 22 Apr 2022, 11:07 pm »

i've been successfull running the omegas with several low-power SET amps.

FullRangeMan · « **Reply #8 on:** 22 Apr 2022, 11:12 pm »

So the Omegas are OK.
You would email GAS-ampzilla to see what they willl say.

bakufu · « **Reply #9 on:** 22 Apr 2022, 11:38 pm »

Quote from: FullRangeMan on 22 Apr 2022, 11:12 pm

So the Omegas are OK.
You would email GAS-ampzilla to see what they willl say.

i spoke with the ampzilla tech at spread spectrum. he had no explanation. obviously there's some incompatibility, but no one, including louis, understands exactly what's going on.

FullRangeMan · « **Reply #10 on:** 23 Apr 2022, 01:27 am »

Quote from: bakufu on 22 Apr 2022, 11:38 pm

i spoke with the ampzilla tech at spread spectrum. he had no explanation. obviously there's some incompatibility, but no one, including louis, understands exactly what's going on.

Strange reply, STM he knows more than it.
Do you have other speaker cable to try with the Omega + Ampzilla?

bakufu · « **Reply #11 on:** 23 Apr 2022, 02:32 am »

Quote from: FullRangeMan on 23 Apr 2022, 01:27 am

Strange reply, STM he knows more than it.
Do you have other speaker cable to try with the Omega + Ampzilla?

i can't make sense of your first sentence. the tech at spread spectrum knows these amps as well as anyone other than james bongiorno, and unfortunately he's no longer with us.

i do have other cables, but i'm really not interested in blowing fuses. i'm looking for a possible cause.

Cheytak.408 · « **Reply #12 on:** 23 Apr 2022, 03:08 am »

Ampzillas we're one of the very few amplifiers would drive Acoustat speakers well. Odd that they are blowing fuses. Are your speaker cables very high in capacitance?

FullRangeMan · « **Reply #13 on:** 23 Apr 2022, 03:13 am »

Very interesting case, keep us posted.

bakufu · « **Reply #14 on:** 24 Apr 2022, 12:22 pm »

Quote from: Cheytak.408 on 23 Apr 2022, 03:08 am

Ampzillas we're one of the very few amplifiers would drive Acoustat speakers well. Odd that they are blowing fuses. Are your speaker cables very high in capacitance?

i'm using take 5 cryo-treated mogami 3104 cables, 6 ft.

Capacitance: 452.8 pF
Inductance: .00066 mH
Resistance: .00512 Ohm

bakufu · « **Reply #15 on:** 5 May 2022, 01:49 pm »

update:

measured resistance on both speakers is stable and right on target (3.7), so it's not likely that either speaker, much less both! was shorting.

reattached to two low-power amps and everything is fine.

here's everything up and running and powered by an eico hf-81.

a riddle wrapped in a mystery inside an engima.

bakufu · « **Reply #16 on:** 15 May 2022, 05:02 pm »

i've decided to part with my beloved omega super-alnico high-output XRS's. since you're here in louis's circle you already know how wonderful these speakers are. my reason for selling is simple: i'd planned to use my omegas as a second set of speakers in my principal listening room, driving them with my ampzilla monoblock amplifiers, but as described above in this thread, these components just don't play well together.

the XRS's are in perfect condition, not a scratch or dent anywhere. along with them i'm selling a pair of deep-hemp 10" subs. all speakers, as shown, in rosewood.

i have the original boxes for all four speakers, but since i picked them up directly from louis's workshop in connecticut, i don't have shipping boxes, so either you'll have to arrange shipping yourself, or you can come pick them up at my place in westchester, new york. in that case, you can get a chance to hear them with a variety of amplifiers (just not with the 300w/ch ampzillas!)

the original cost of all four speakers was 7K, and i'll be asking 6000, which really is a great deal given how backed up louis is these days. i'll entertain reasonable offers.

in the event that i'm unable to sell them to fellow omega enthusiasts, i'll repost in the equipment-for-sale section.

mick wolfe · « **Reply #17 on:** 15 May 2022, 08:52 pm »

Before throwing out the baby with the bathwater, I'd try another amp. Now this especially if you feel the Omega's have a great deal of potential. Just a suggestion.....don't shoot the messenger.

bakufu · « **Reply #18 on:** 15 May 2022, 10:27 pm »

Quote from: mick wolfe on 15 May 2022, 08:52 pm

Before throwing out the baby with the bathwater, I'd try another amp. Now this especially if you feel the Omega's have a great deal of potential. Just a suggestion.....don't shoot the messenger.

the omegas work fine with three other amplifiers of mine. just not with the ampzillas. there's nothing wrong with either the amps or the speakers, but for reasons no one has been able to explain, they don't work together.

SET Man · « **Reply #19 on:** 15 May 2022, 11:03 pm »

Hey!

Ironic isn't it? That Omega speakers, they are easy to drive would blow fuses of 300wpc SS amp.

Someone here already mentioned speaker capacitance. I can't think of anything that could cause the problem, but the speaker cable you are using with right now combined with connectors on the cables and speaker could all add up to the point that could cause the amp to blow.

If you like the sound of the Omega ( I'm a Single Driver user here and I know there's something special about the sound that SD speaker without xover can do) I'd suggest you try another speaker and see. Let me know if that works and how the combo of 300wpc SS and the Omega sound.

Buddy