C90 Blowing with Mark IVa Short Head

[dunkonu23]

Hi,

Firsts for everything. I blew a Mesa C90 today while playing through my Mark IVa into a Grendel Sound Dead Room iso cabinet. Volume was at 3. Question is this: How reliable are Mesa (Celestion) C-90's?

Thanks,

Scott

 

[Ultron]

Bump for an answer....I have a Grendel Dead Room and a MC90 I was planning on swapping in and cranking with my Mark III.

 

[dunkonu23]

Bump for an answer....I have a Grendel Dead Room and a MC90 I was planning on swapping in and cranking with my Mark III.

I'm thinking I just got a bad C90, but you never know. There are a lot variables in this question. The Dead Room is a sealed environment while the Mark IV combo is open back, so you never know. When I called Mesa for a replacement, they didn't seem too concerned that the speaker was in a sealed environment. Mesa, btw, was great with me. They've already sent out a replacement speaker--free of charge.

I will say that the Dead Room with a C90 seems to be the way to go for me. It sounded absolutely awesome--until it blew. What is clear is that the V30 is NOT the speaker for this application -- a high gain, high output Mesa Amp. I've used a V30 (English made) in the cabinet and it cannot handle volume past 2 without breakup on R1 with my settings. Unfortunately, for right now, the V30 is all I have until the replacement from Mesa arrives.

Scott

 

[zenabI]

How much bass did you have, did you use the EQ, bass etc? Not a smart idea with just one speaker...

Anyway, some sort of attenuation device is recommended.

 

[dunkonu23]

Bass is at two. I bounce around having the eq on and off, depending on what I'm going for. Generally, it's on because the sound is much tighter. With volume only at three, I'd like to know the rationale behind using an attenuator? I mean, I understand the purpose of an attenuator, power soak, etc. and I have one. Remember, I blew a C90 and I'm taking steps to avoid popping the V30 now installed (until the replacement C90 arrives) by turning the volume down significantly--around 1.8, now.

Scott

 

[zenabI]

Do you run the amp at full power? You should run it in tweed if you only have one speaker IMO. I bet you could even blow a 2x12 with this head in full power because it's a really powerfull and loud amplifier.

I always run it at tweed, class A and triode when I'm playing with my 1x12 at home.

By the way, was the speaker broken in. You always need to warm up speakers when they're new. You'll blow them really easy if you don't do that.

 

[dunkonu23]

Do you run the amp at full power? You should run it in tweed if you only have one speaker IMO. I bet you could even blow a 2x12 with this head in full power because it's a really powerfull and loud amplifier.

I always run it at tweed, class A and triode when I'm playing with my 1x12 at home.

By the way, was the speaker broken in. You always need to warm up speakers when they're new. You'll blow them really easy if you don't do that.

Yep, full power. My thought on that is that the combo uses the same speaker and it's the same amp so in my way of thinking that shouldn't be a problem. Breakin--yep, I followed the procedure on the Celestion web site. I do thank you for the ideas. Keep them coming if you have more.

What I'm thinking is either the speaker was defective or... and this is something I don't want it to be--back pressure. Since the Dead Room is a sealed environment, both behind the speaker and in front of the speaker, after a bit of play, the speaker may not be able to breathe properly and that may cause heat build-up in the voice coil. The way my speaker blew is with a complete open circuit--no resistance at all between negative and positive connectors. If this is the case, and if the new C90 blows, about the only way to fix this is to put sound proofing foam behind the speaker or to vent the cabinet, front to back to help balance pressure.
Neither of those solutions is very attractive to me.

Then there's vibration. There's a helluva lot of vibration in the iso cabinet. Any defect in manufacturing will show up in that environment.

Like I said this is the first time in many years of playing that I've had a blown speaker, so I'm a bit stunned.

Thanks again for the responses!

Scott

 

[zenabI]

Attenuator is the way to go IMO. If you run it in tweed you might not need an attenuator or you won't need to attenuate as much atleast. I have zer0 experience with ISO-cabinets but I'm actually building one at the moment

Most people I've talked with have used attenuators when using ISO-cabinets just because of this problem with blowing speakers.

 

[dunkonu23]

Thanks again!

See, that's just it. I've researched this and I haven't found one instance of someone blowing a speaker that was rated at the amp's power when using an ISO cabinet. If you have a link or two, it would be greatly appreciated. What I may do is buy a less expensive speaker for testing... I dunno.

Scott

 

[JOEY B.]

The rated power of any MESA amp does not include power amp clipping. Therefore a 100 watt Boogie may put out twice the wattage at clip. Ask Phyrexia about a 180 watt C+ into a 200 watt EV thiele cab.

 

[phyrexia]

I bet it was just a bad speaker. I've put some C90s through hell. It wasn't really really new, was it? How much time did you have on it?

 

[dunkonu23]

Nice explosion!

Yeah, it was a week old, broken in per Celestion's site. I ordered it from Mesa directly. I, too have put a lot of speakers through hell in my time (a lot of years... more than I care to admit to) and that the was the first blown speaker.

Oddly enough, if anyone wants to hear a clip of what a speaker sounds like while it's blowing... I've got one. It will take a couple of days to get online, but it's kind of cool.

Scott