High vs low wattage audiophile speaker amps - Page 2

The best sounding system I have consists of a 2 watt/ch Decware SET amp paired with some efficient (95db iirc) Parker speakers.  Can't rattle the windows but it can get surprisingly loud.  That's beside the point however, the sound is so musical and transparent it still makes my jaw drop.  The imaging/soundstage is to die for.  It's amazing what 2 puny watts can do.

 

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Damping factor (eight divided by output impedance) is a measurement touted by some manufacturers because it is easy for transistor amps to achieve impressive, and utterly meaningless, numbers (inherently low output impedance).  Both distortion numbers and damping factor can be made even more impressive, numerically speaking, by use of high feedback.  But, just take a listen to solid state amps with really high feedback and those of companies that try to minimize the amount of feedback (e.g., Ayre).  High feedback leaves a distinct sonic signature--if you like that kind of sound (a lot of people apparently do, given its prevalence in the market), then you won't be interested in low output, purist designs anyway.

 

Given the right kind of speakers, a damping factor of 2 may be adequate.  For more universal applications, 4 would be nice and anything beyond 8 probably makes damping factor a non-issue.

This ^ ^ was a good answer.  There is even a school of thought -- mostly among the radical SET folks -- that high damping makes for bad sound.  The higher the damping factor, the more "control" the amp has, and in theory the more closely the movement of the speaker element will exactly match the signal.  However, some believe that the natural decay of musical notes are artificially truncated by amplifiers with very high damping factors.

 

I actually don't have a point of view on the topic, but as with most things audio, too much is not better than just right.

 

Frank

Good point, Larry I.

One small side note, though. A lot of OTL tube amps get recommended to people here that have an output impedance above the impedance of the headphones. You don't want impedance to go upside down.

With audio no absolutes seem to apply. I use Grados with OTL headamps and the sound is awesome. I have no doubt the OTLs output impedance is higher than the Grados 32 ohms.

 

I have an 8 watt push pull integrated that drives my 89db transmission line floor standers incredibly well. I prefer the sound of the 8 watter over a very good sounding 150 watt LM3886 custom power amp with the transmission lines. On my high sensitivity 94db monitors the LM3886 amp just matches better; probably due to the speakers low impedance??

Many OTL tube amps are definitely quite a bit higher than 32 ohms out. Grados actually have a very very flat impedance curve (compare RS1/SR225 to Sennheiser HD600/650/800 on headphone.com), which means that the losses due to a low damping factor (less than 1 in this case) won't necessarily cause the usual frequency response aberrations you'd expect with more typical speakers & headphones. In that sense, Grados actually seem to be quite "tube friendly". As always, the answer to anything nontrivial just "depends" on the specific context in question, and the oversimplifications we often use to dole out recommendations can allow some otherwise nice match-ups to fall through the cracks. 

 

The main consequence here will be a loss of power delivery from amp to headphones, as most of the amp's output power will be dissipated as heat before it hits the headphones - and the actual ratio dissipated vs. delivered will depend on the actual output impedance. I suppose my concern here would be more about the headphones' effect on the amp, rather than the other way around. 

 

Wow man, I know there are some real sweet sounding low-powered tube integrateds out there, but 8 Watts on 89dB/Watt speakers just would not cut it for my listening habits. Again - different contexts => different answers :)

 

I like a lot of headphones when driven with a lowish damping factor, often less than 1!

 

In speakervile, I like single drivers driven from amps with low damping factors, BUT extreme care must be taken with speakers with passive crossovers which is the vast majority of multi-driver speakers. The crossover points are conditional on the output impedance of the amp (which is what makes the damping factor) and things get weird quickly. If you look back to when damping factor started to be the most important thing you will see it started around the time McIntosh started picking up steam... It makes sense - their amps sound like poo with single driver speakers, and amps with low damping factors simply dont work with their very complex speaker crossovers. 

 

There is no reason that an amp with a low damping factor could not work well with a multi-driver speaker with passive crossovers, its just that its so rare for anyone to design them to work together. 

8 watts with 89 db is fine if you listen nearfield. By the way this is Earl/ sacd lover. My hard drive crashed and I couldnt get into my profile because I forgot my password. I also moved and had a new  email address so I couldnt get the password sent to me. So I ended up reregistering as Ilovetubes. I hardly ever listen to headamps anymore but I have tube amps and speakers everywhere.

 

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some truth to the low wattage trend...Instead of tube rolling, I'm in a pursuit of the right chip sound. I am really taken to the t-amp chip. Great sound from the lesser power chips 2020 and 2050. I have a dual 2050 setup. Not really dual mono. Single controller chip. 40wpc. Great sound. Many imitators. Not much bucks. I'm tempted to go with more power, within similar architecture. Cant pull the trigger. I love it! Not concert level sound, but my hearing is better for it.

The single (2 actually) most important piece of information about a speaker - other than listening - is its electrical load and phase diagram.  Low power amps and especially DHT SETs (8W or less) crave speakers that are as close to a high impedance resistive load as you can get.  This means a relatively flat impedance and phase angle curve across all frequencies, with no extreme negative phase angles (if any).  The problem is that many mfrs don't publish this information, just an average impedance and this can be very misleading.

 

My own experience is that except for music with large dynamic swings and many instruments, how easy a load your speaker presents to the amp trumps sensitivity.  I use an 83dB sensitive speaker (LS3/5A) with a 2A3 amp (3.5W) and it works fine in a small room, same with my 90dB speakers.  For large orchestral music with big dynamic swings, you also need to worry a lot about sensitivity and probably want speakers that are both an easy load and 100dB or so sensitive.

 

I also think damping factor is overplayed.