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Topic: Tube Amp With No Speaker Load |
Jon Light
From:
Saugerties, NY
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Posted 29 Mar 2013 4:40 am |
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I am well aware that you don't do this and I'm super careful/paranoid that it does not happen.
But I'm wondering---
--here we have a Peavey Classic 50/50 rack mount EL 84 power amp with all sorts of outs on the rear panel including line outs and direct outs and a lot of mono/stereo individual channel impedance options.
The manual has NO warning about running without a load. It seems to me that I've seen such a warning in manuals of typical combo amps.
I'm recording direct and using a Power Soak to moderate the speaker output since I'm monitoring thru phones off the recording rig.
So--is there any chance I can just run without the speaker? I doubt it but I'm wondering.
A side anecdote. I had an Ampeg fliptop---an SB-12---when I was 13. I knew NOTHING about tech stuff and had no thoughts about tube/solid state. I don't know that I even knew that it was a tube amp. The speaker connection was not a cable---remarkably, the two metal butterfly clamps that hold the flippin' head to the cabinet are the speaker connections. Who knows how many times the head was on---I don't recall any standby switch---with no connection. Nobody ever told me to care. When I sold the amp 10 years later (damn!) it still ran just fine.
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Brandon Schafer
From:
Indiana, USA
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Posted 30 Mar 2013 6:43 am
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If you like the transformers in your tube power amp, I would never recommend running without a load from a speaker or other dummy load. From what I understand, tube amps need the load to operate safely. Every time.
I'm sure there are times we all have goofed and turned a tube amp on without a load for a bit. But, I just don't think it's a good practice to get into. |
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Bud Angelotti
From:
Larryville, NJ, USA
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Posted 30 Mar 2013 7:09 am
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Is no load on a tube pre-amp bad as well? No power amp, just the tube pre-amp?
Thanks - Bud
_________________
Just 'cause I look stupid, don't mean I'm not. |
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Brandon Schafer
From:
Indiana, USA
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Posted 30 Mar 2013 7:20 am
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| Tube preamps are okay to run plugged into nothing. |
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Jon Light
From:
Saugerties, NY
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Posted 30 Mar 2013 7:34 am
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Yeah, Brandon. Like I said, I am paranoid about this and check & double check before I flip my Fender amps out of stand-by and I check the cables periodically for shorts and breaks.
But it seems to me I've seen amps that had some sort of protection built in that somehow allows you to not have a speaker plugged in. Possibly it is just a breaker that trips to protect the amp rather than a way to actually run the amp without load.
And possibly I'm just mistaken and I've never seen such a thing.
This really isn't important---the attenuator is doing the job. Just fishing for info. |
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Mike Wheeler
From:
Delaware, Ohio, USA
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Posted 30 Mar 2013 7:48 am
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Most commercially available guitar tube amps have a 1/4 inch shorting jack that shorts the speaker connections, when no plug is inserted, to prevent amp damage. Any good design would have such protection. Check your amp, though, before assuming this to be the case.
Note: There are some amps (like older Ampegs) that have creative ways of connecting speakers, and therefore can be accidentally run with no load whatsoever.
And Brandon is correct...NEVER run a tube amp with no load. I wouldn't risk my tube amps, even if someone else said it would be OK...not worth the risk to me.
By the way, Jon, using that Power Soak does put a proper load on the amp.
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Best regards,
Mike |
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Jon Light
From:
Saugerties, NY
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Posted 30 Mar 2013 7:59 am
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| Mike Wheeler wrote: |
By the way, Jon, using that Power Soak does put a proper load on the amp. |
Yeah, I understand that.
Even at full attenuation it bleeds some sound. At 3 in the morning I was wondering if I could cut that to zero. With headphones on, I keep pulling them off and checking room sound to make sure that I'm not shaking the neighborhood (I'm not).
And point taken re: just not doing it. I agree, it would be an expensive lesson to guess wrong and not all that enlightening. It isn't going to happen.
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b0b
From:
Cloverdale, CA, USA
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Posted 30 Mar 2013 10:04 am
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When I want to disable a power amp, I remove the output tubes. This typically has no effect on the preamp output. I do this with my Hammond organ to use it with headphones.
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-𝕓𝕆𝕓- (admin) - Robert P. Lee - Recordings - Breathe - D6th - Video |
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Jon Light
From:
Saugerties, NY
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Posted 30 Mar 2013 10:28 am
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Ok b0b. Now you've muddied up my waters. This changes the subject.
This is a power amp, not a head. I'm running a tube preamp in front of it.
The only reason I'm going through this amp is for power tubes.
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So now I'm thinking...is it possible that by going out from the XLR jack direct to the computer I am bypassing the power tubes? If so, I might as well just go direct from the preamp. I guess I'll have to experiment. |
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Mike Wheeler
From:
Delaware, Ohio, USA
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Posted 30 Mar 2013 10:54 am
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Jon, sorry if I sounded preachy...not intended.
(had a bad idea here and deleted it) 
Yes, the XLR and Pre-outs are before the power tube stage...no power tube sound there. You'd have to tap the speaker out to get that, like some direct boxes can do. (never used one myself)
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Best regards,
Mike |
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Jon Light
From:
Saugerties, NY
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Posted 30 Mar 2013 11:45 am
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Not at all, Mike! No worries.
Actually, that's an angle that didn't come to mind--using the Soak at full attenuation and not going out to the speaker.
The 'full' dial position is actually called 'headphones'. I just googled up a manual and at this setting you can either plug headphones into the speaker out or run direct to the board and disconnect the speaker.
So there we have it.
But I'd love some speculation on my last question.
Nothing to do with speaker output----if I am coming out of the XLR direct jack of the Peavey power amp to the board, am I just taking the direct preamp signal, PRE power tubes? Or would it be POST power tubes? Since I am monitoring from my DAW, there's no reason to even use the power amp if its tubes are only driving the Power Soaked speaker and not the direct-out signal. |
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b0b
From:
Cloverdale, CA, USA
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Jon Light
From:
Saugerties, NY
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Posted 30 Mar 2013 11:58 am
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| There we go. Excellent. Thanks b0b. |
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