Can low output tube amp drive inefficient speakers safely?

imready

imready

it's good to be the king!
I know there was a thread about this topic a while back but I have no idea how to find it. Would 15 wpc tube amps be in danger driving my power hungry Dahlquist DQ-20's? I know with SS stuff the only amps I have seen damaged have been amps with moderate output trying to inneficient speakers. I would expect it would have similiar results in tube equipment but I really don't know. :scratch2: john
 
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Maybe someone else with more knowledge can chime in but I can't imagine how it could damage the amp unless it is poorly designed to begin with. I suppose if you drive it far enough into overdrive you might damage the speakers. If the designers didn't skimp on the OPTs then the only result should be increasing distortion as the waveform gets squashed.

mike
 
With a tube amp poor quaility sound is what you would have ,with no harm to the speaker ,tube amp clip differently than solid state amps , they don't produce the harmonics or have the current availible to do the damage like solid state amps .

Mark
 
It is certainly less likely to damage a tweeter with a low-powered, transformer-coupled tube amp than with a solid state amp of similar continuous power rating. They do indeed "clip differently" but they also do indeed produce plenty of harmonics when they (finally) do. That's why R&R guitarists (particularly) prefer tube amplifiers to this day.

As an example, I use AR-3s with my Maggotbox console amp (push-pull EL84) in the basement regularly for nearfield listening with absolutely (absolutely) no complaints.
 
Tube amps are less likely to clip into innefecient speakers than Solid State ones, so you probably won´t be able to attain realistic listening levels, but don´t run the risk of damaging anything.

That said, if you hear things distorting, just turn the volume down.
 
Damage, no. Produce satisfactory levels of sound, probably not. As mentioned, clipping SS will fry things, but running a tube amp flat out just sounds bad, it doesn't actually break anything.
 
mhardy6647 said:
It is certainly less likely to damage a tweeter with a low-powered, transformer-coupled tube amp than with a solid state amp of similar continuous power rating. They do indeed "clip differently" but they also do indeed produce plenty of harmonics when they (finally) do. That's why R&R guitarists (particularly) prefer tube amplifiers to this day.

As an example, I use AR-3s with my Maggotbox console amp (push-pull EL84) in the basement regularly for nearfield listening with absolutely (absolutely) no complaints.
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Nearfield listening would be a good description of the environment this system will be situated in. Guess I have nothing to lose by seeing if it is acceptable. I have lots of tube amp age speaker that will sound very good if it doesn't work out.
 
*LOW VOLUME ONLY........................(*probably won't damage anything)

Trust me.....I just went through that agonizing process.....with a 7 1/2wpc Magnavox amp.
The magic word is.....HORNS!!


Steve
 
similost said:
DQ-20 on 15 watt amps of any style... :nono:

You need some real power...
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I can make some real power in SS , though they recommend not driving 4 ohm loads with the amps I have in bridged mode I have done it ,probably 500wpc into 4 ohms. They sounded excellent but I don't want to thrash the amps so I really need a different source of power. Since I bought/bartered 3 amps last month I need to chill for a while on the audio spending at least until I pay off my purchases. I hate to shelf the Dahlquist's and I know driving them with 15 watts is most likely not going to do it for me. However, I will check them out anyhow just to be sure now that I know it won't hurt anything in doing so. I generally don't rock out on any systems in the house besides the main one, the rest I listen to primary after the wife goes to bed.
 
inefficient speakers

Best compromise here is to use a tube pre with a high powered ss amp. Still get the tube warmth and soundstage from the preamp but have plenty of power from the ss amp. Of course the horns are a fantastic suggestion too.
 
It will probably sound wonderful at low /medium levels, like its limitless, that may you want to turn it up and it may well distort.

I found something like this driving B&W DM2a's with a Rogers Cadet III, only a few Watts per channel output, but nice sound quality.

Should be no damage though.
 
Clipping a tube amp won't break speakers? I don't believe it. The only way that's not possible is if it's low powered (as is the case here).

Both driven to equal levels of clipping, a 15W tube amp and 15W SS amp are both, IMO, equally likely to cause (or not) speaker damage.

The biggest issue with clipping is not the harmonics, it is the 3dB (twice as much power) you could generate with severe clipping as the waveform squares up. If you drive it that hard, and that power is enough to damage the speakers, then it will regardless of the type of amp, IMO.

In this specific case, I would speculate that no matter how much clipping you generated, a 15W amp probably wouldn't damage the speakers unless they have very fragile tweeters.
 
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you are more likely to damage speakers by under-powering them with audible distortion as opposed to damaging them by properly powering them with audible distortion. If your not distorting them, slash clipping the amp you shouldnt have an issue, but like was said before, when you hit the point where your squaring the wave, thats when id be worried about speaker damage

Mark
 
imready, let me first say that's an excellent question.

Without getting into the farmost hidden depths of the technical aspects of the peripherals in question, let me say that I would consider your question/proposal of usage to be what I consider a highly impractical mismatch of components.

Why???

Those DQ-20's require sufficient power in order to give them the characteristics they're known for. Remember, a 15W per channel tube amp isn't going to hit near that level until it's really pushed hard (and depending on the source plus the musical content itself). If you're not continuously hammering 100+ watts per channel into those DQ-20's, they're not going to respond and sound as they should.

As far as actual damage occuring to the speaker. . . it's always possible.

However, as far as damage to the amp is concerned. . . who knows. You could end up driving it too hard to get the volume you're looking for, red plate the power tubes if the bias is too high or the coupling caps haven't been replaced; and then they may eventually short out and kill one (or both) of the OPT's. Now you're having a really bad day.

ALWAYS use a good speaker/amp matchup. If you're questioning others about your intended selections, chances are that deep down inside . . . . you're really not comfortable with it in the first place.

. . Falcon
 
Guys, thanks for all your input so far, I am always grateful that you take time to respond to my questions. Just so you know, I was fully aware that this is a bad match-up with the DQ-20's and my little tube amps. My biggest concern here was hurting something checking out this combo to see if it was going to sound halfway decent or risk of damage was too great to even mess with it. The other part of my thinking, well, I know how these sound driving them with 80wpc SS compared to 400-500wpc SS, the difference is night and day. What I was thinking is because the nature of tube wpc output is very different than SS wpc output, would the low output tube amps sound better driving the speakers than the low output SS combination. Just wondering if the ratio of quality output would be the same between tube and SS?:scratch2:
 
I don't remember ever seeing a "my low power tube amp has damaged my speakers" thread, if that tells you anything.

I run a 15wpc tube integrated with my Vandersteen 1C's and they have never sounded better. The Vandersteens are one of those speakers reported to need plenty of power...and are a nominal 6 ohm rated. 100+ hours of use so far and no problems with speakers or amp!
 
Two and a half months later, I've finally moved enough audio equipment around to give this experiment a try. I have 3 systems in the house at this time and a couple of them are for late nights when my wife sleeping. I am driving Dahlquist DQ-20's with a Harman Kardon 5000x tube receiver that puts out 25wpc. The DQ-20's are a 4 ohm load that are capible of handling goobs of power, I don't have the specs with me but I was driving them with solid state gear that put out 250w into 8 ohms and I'm sure much more into a 4 ohm load. Source was a Yamaha PX-3 with MM cartridge using amps phono stage.The Harman Kardon is running a little warmer than normal but none of the transformers are even close to being too warm to touch. It drives them nicely at low volume but starts to distort badly much earlier (about 2/3 of max)than it does pushing an average 8 ohm load. Bass is still firm with no noticible change in the tone qualities of the amp. I also hooked up a cassette deck and observed that same conditions as with the turntable, distortion early and ugly but sounds very nice a low volume. It will remain in my loft system and though it won't get used much, it will be enjoyable when I do want to watch is snow out the front of the A-frame and listen to some soothing tunes. John
 
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