Speaker made awful sound ...terminals? Opinons, please.

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Speaker made awful sound ...terminals? Opinons, please.

Postby strattarts on Wed Oct 14, 2015 4:29 pm

I have a fairly powerful combo, an Encore 65 by Peavey. All tube, great tone.(I'm not a peavey guy, but after hearing
this amp, I went ahead and bought it.)
I had an eminence red white and blues in it which sounded pretty good, but is new and 8 ohms instead of the 4 ohms my amp wants,
so decided to plug in this Celestion Century I have, which sounds great in the amp.
Anyway, I had it cranked up and while playing I slide up the neck to a C note, or thereabouts on the big E string, and this
AWFUL "Krckcrrkfkc" sound came out. That's a technical description for ya. No, but it almost sounded like a dirty component
being driven really hard to where it just sent out an awful sustained crackle. Didn't seem like it was the speaker itself.
*** >>> I noticed when I mounted the speaker that one of the terminals (clip ons) was not that tight. Kind of 'rocking' a bit,
but connected for sure. I was wondering, symptomatically speaking, if this horrible sound (which was also kind of a cutting out sound,
as far as it was NOT a musical tone accompanied by a distorted sound, but just an awful growling, kkkrkkchkk kind of sound)
would possibly be indicative of the terminal vibrating at loud volumes. It happened twice while I was playing it, both times, and not to
far apart (in time), at around the C note. Then I couldn't get it to do it again.
To note, I have also been having a problem with vibration in the amp which is one reason I decided to try this Celestion I've had lying around.
There's nothing wrong with the Eminence. The amp buzz (combo buzz) seems to be coming from inside the chassis, or possibly
the chassis against the wood. When I squeeze the chassis and top of the amp together with my hand, the buzz/rattle stops.
However, at a lower volume, with the right note played, I can hear the rattle, sounding like it's coming from inside the chassis.
Kind of a metallic rattle. Also goes away when I squeeze the chassis against the cabinet top. (there could be more than one rattle)
I add this last paragraph because I'm wondering if at loud volumes the rattling component inside could be pushed to a point
of kind of cutting out or shorting out / failing. I am not a tech by any means, but might be able to hunt it down with some advice.
Also, to note, I did not get the 'awful' sound when the eminence was installed, but the terminals seemed to fit tighter, so that's one
reason I suspected that.
So, is it likely or possible that it would make that kind of awful sound from a terminal shaking to a point of 'disconnection', or
would it simply cut out or in and out?
I realize with this description it's hard to know what is the cause and what's going on, but I'm just trying to pick
the brains of the experienced, if you will.
Thanks.
strattarts
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Re: Speaker made awful sound ...terminals? Opinons, please.

Postby pdf64 on Wed Oct 14, 2015 5:48 pm

An intermittently opening speaker circuit is about the worst scenario for a tube amp; it could cause enough damage to make the amp unviable to repair.
The Celestion may be more efficient and so louder at any given setting, than the Eminence, especially as it's 4 ohms, thereby exacerbating any vibration issues.
It would be best for a competent tech to check it over. Unfortunately tube amps need tubes and tech time, once in a while.
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Re: Speaker made awful sound ...terminals? Opinons, please.

Postby strattarts on Wed Oct 14, 2015 8:15 pm

Thanks. The Celestion is also 8 ohms, and it's a neodymium speaker and is supposed to be very effecient and
loud. It does not seem that much louder than the red white and blues, but the eminence seemed to be a pretty loud
speaker as well. I don't know, though, that amp is just loud to begin with too, lol.
I was a little apprehensive about using the celestion because I feared the effeciency along with the
ohmage mismatch (though this is said to not be a problem at all, especially with an amp like this with large transformers...(i guess) )
might cause some sort of problem. I'm not saying it has. It sounds good. I'm just wondering, still, what caused the
horrible noise.
You mentioned the intermittantly open speaker circuit being a very bad thing ( I have heard of the dangers),
but do you think I could be right about the terminal vibrating and causing disconnection? I can clamp it down a bit
with plyers and see if it does it again. I guess I'm also wondering if this danger would happen, or the damage would be
caused, quickly, or whether it would have to remain 'unloaded' or whatever causes the problem/danger, for a longer duration. ???
I have the original Scorpion 4 ohm which sounds fairly good, but a little flabby and more rumbly it seemed. It did seem a little richer and I was attributing that to the 4 ohms...and possibly being broken in.....very broken in, lol. I am looking for a 4 ohm speaker.
I think a 4 ohm will sound better. Some say the difference ( between a 4 ohm and 8 ohm in a 4 ohm amp) is
barely noticeable, but I think I noticed a considerable differnce in volume and tone w/ the new Eminence. Although
it's a very different and new speaker, so differences would be expected....and welcomed,...since that's the idea of
upgrading, but although the eminence sounded better in general, there was loss of power, somewhat, and a less deep or rich tone,
and I'd like to see if it returns with a 4 ohm.
strattarts
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Re: Speaker made awful sound ...terminals? Opinons, please.

Postby OldSchoolDave on Thu Oct 15, 2015 12:46 am

strattarts wrote:I can clamp it down a bit with plyers and see if it does it again.


Be careful not to short the terminals when/if you do this.

How far up are the volume controls when this behavior is displayed? Could the speaker cone be moving too far out of its excursion range? Does the speaker magnet sit closer to the transformers than the original did? There could also be a tube rattling or another component (resistor maybe?) that shorts out at that particular note & volume.

Do you have an external speaker cab you could power instead? That might help the troubleshooting process. My guess is, the amp's going to need some bench time.

Dave
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Re: Speaker made awful sound ...terminals? Opinons, please.

Postby strattarts on Fri Oct 16, 2015 4:13 pm

Thanks for the input oldschoolDave
I will reply to your questions here...
------
(Be careful not to short the terminals when/if you do this.)
What do you mean by this, exactly? I was just referring to crimping down the clips a little on the speaker terminals and
making sure they're secure and not floating or loose. One of the clips, as I mentioned, will rock around a little if you move it
with your finger. It's not horribly loose and obviously making contact fairly well for the most part, but I was wondering if at high
volume, it might have caused that sound, which again, was pretty awful. But no damage seems to have been done.


(How far up are the volume controls when this behavior is displayed?)
Well, I had it up about 5 or so, which on that amp, is damn loud. As loud as I'd want to push it generally. And it sounded
fine. Just when I slid into that C note and again shortly after than it did it around that same note. Seemed to 'not repeat', though,
when I tried to get it to do that again a minute later.

(Could the speaker cone be moving too far out of its excursion range? )
I suppose it's possible. Didn't seem to be a result of pure volume, though, as much as something about that C note (or thereabouts)
causing a vibration or something to that effect.

(Does the speaker magnet sit closer to the transformers than the original did? )
No, the neodymium magnet is small in comparison to the 120 watt RW&Blues speaker and sits comfortably away.
I don't know how powerful the neodymium magnet is in that celestion century, though. Kind of doubt that's the problem.

(There could also be a tube rattling or another component (resistor maybe?) that shorts out at that particular note & volume.)
I have been experiencing some light tube rattle. The tubes are Peavey 6l6's and likely originals, 30+ years old. The tubes
sound good but I suppose the tube could rattle hard at a loud volume. Been wanting to try some new 6l6's in it to see
how they sound and so forth.
Do you think tube rattle can rattle so hard that it shorts and makes a awful calamity noise?

(Do you have an external speaker cab you could power instead?)
I do have a 2x10 cab that I tried it with a few months ago. It's 4 ohms which matches the amp.
It sounded really good through it, but I didn't run it too loud for long because the cab is a homemade cab out of an
old audio speaker, and although it does well with a different low powered tube head I have, it rattles and buzzes
when the Encore drives it too hard. It's definitely the cab in that situation. Weak baffle board and just a poorly put
together cab as far as handling any real power. Sounds good, though, at lower volumes.
As I remember, it was very quiet and sounded good. Seemed to indicate that the rattles, etc., in the Encore are
a 'combo issue'. I love combos, but this damn near makes me want to go to a head / cab setup. If I hadn't put
so much time into retolexing my Encore in a nice seafoam green, I'd think about chopping the amp into a head, lol.

I'm thinking of trying some tubes, but I did find a 'clicking' sound when the amp is off and I push up on the chassis.
Gonna try to figure out where that's coming from today. I think that is almost for sure the cause of a metallic rattle that
I've been having, but I don't know (and don't think...though I could very well be wrong) if that's the cause of the bad
sound I got a couple of times.
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Re: Speaker made awful sound ...terminals? Opinons, please.

Postby OldSchoolDave on Fri Oct 16, 2015 9:21 pm

strattarts wrote:------
(Be careful not to short the terminals when/if you do this.)
What do you mean by this, exactly? I was just referring to crimping down the clips a little on the speaker terminals and
making sure they're secure and not floating or loose. One of the clips, as I mentioned, will rock around a little if you move it
with your finger.


Oh, that's fine. When I read your earlier post, I was thinking you were going to try this when the amp was exhibiting the bad behavior.

The easiest non-tech thing to do is to swap tubes with known good examples - preferably, one at a time (or in pairs, with the Power Tubes). You may find the culprit that way.

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