Axiom Home Page Forums General Discussion Technical Questions Tube Amp Drive

Hello:
I have a Soundstage One Hybrid Tube Integrated Amp (25 wpc, Chinese knock-off), and would like to know whether It would be capable of driving the Axiom MT 80's or MT 60's. I play at moderate home levels, and obviously don't expect nor do I want to, shake windows or walls. My primary music concerns are are classical and jazz (if that should make a difference).
Thanks

Nice product at that price point. However, I would avoid the 4 ohm M80s with that amp. You may get away with using the 8 ohm M60s or the m50s if you play at moderate volumes, though I doubt you will fully experience what these speakers can do with that amp. While most of the time the amp will coast along on a few watts, at high transients such as with kick drums or strong bass which can produce instantaneous peaks over 100db you risk clipping the amp or hearing distortion.

This is a small forum, you really don't have to post the same question in more than one location.

Thanks jakeman, but now my confusion.
My 25W amp can give me ~ 14 dB. If the M60's or M80's require 10W min, then I have ~12 dB [ 10*log(25-10) ] to play with.
The M80's have an input impedance = 4 ohms, and an spl=95 dB/W/m., and I should be able to hit 107 dB (95 + 12).
The M60's have an input impedance = 8 ohms, and an spl=93 dB/W/m., and I should be able to hit 105 dB (93 + 12).
And both require 10W min. to be driven.
This tells me that for a given I/P power, regardless of the input impedance, the MT80's are easier to drive than the MT60's.
Where did I error?
Thanks

My apologies! I oroginally posted in "Stereo", when I should have posted in "Technical". I'll keep future posts in one or the other.

Nothing to apologize for, we are a friendly bunch.

You could be reading too much into the sensitivity rating of the speakers when you should be more concerned with how much of a load the speaker presents to the amp. Generally speaking a 4 ohm load draws twice the current of a 8 ohm load. With any amp the maximum power it can deliver depends on the current and voltage. Some of you may have seen this expressed at P= I*E or power = current times voltage. A low impedance load will mean more current flows and based on the voltage that means more power demands.

Also keep in mind that the quoted impedance of the speaker is not constant across the frequency range. Swings up or down a few ohms are normal depending on frequency. So at 2 ohm swings for example you would be drawing even more current into the speaker. While the Axioms can certainly handle the current, the question is will your amp be able to supply the increased power demanded by the speaker. While much depends on how loud you want to play the speakers, you will find the limits of your amp before those of the speakers.


At very low volumes you may not have a problem but I suspect at reasonable listening levels or during sharp transients you would clip the amp or at least have distorted sound with the 80s. Contrary to what many people think underpowered amps driven to clipping are more likely to damage speakers than having beefy powerful amps. The 8 ohm 60s would be a better choice and make less demands on your amp at moderate levels. Besides, I think it has the best tonality of all the speakers in the lineup and would likely produce an lovely airy midrange with that tube amp.

Why are you subtracting the 10W minimum power spec from the 25W? It's not as if the M80 consumes those first 10W.

As I understand it, the minimum power spec tends to be indicative of the power needed for "good" bass output. If you take a look at the M80 frequency response plot, the SPL at "lower" frequencies is attenuated. Hence, putting in a minimum of 10W will bring the SPL at say 20Hz up to around 75dB which is a respectable level. It will also blow your ears off at higher frequencies so that's not a great way to increase low frequency performance .

The tube amp won't clip in the same manner as a solid state amp. I wouldn't be concerned about damaging the speakers with the tube amp.

However, you'll be drawing excessive plate current if your amp is not rated for 4Ohm speakers and you'll be replacing tubes frequently.

Mojo: Thanks for correcting my misunderstanding. The extra 10W I was subtracting now gives me more headroom.