Monday, January 26, 2009

Amplifier Shootout: Tubes vs. Solid State

This weekend I pulled my UREI 813A cabinets out of storage and connected the Altec 604 and Eminence drivers back up. It has been five months since I've last heard these beasts so I was a little surprised on how good they sounded. I got familiar with their good points again - the dynamics are simply incredible. There is a clarity and rightness to the overall sound that easily surpasses many speakers that I've heard. But of course no speaker is perfect - there is no big wide soundstage and if you don't sit back far enough the drivers will not integrate all that well. The UREIs are a bit forward and dry too. They also require loud playback levels to sound their best which makes them perfect rock n' roll speakers but not all that suited for baroque. This playback level can also makes them less than popular with anyone not actively listening to them.

With all that in mind, I decided to compare the Threshold S/500 to my DIY Single ended EL156 tube amplifiers. In fairness I invited my fellow audiophile friend over. He has many years of experience with the UREIs - owning among many things a pair of 'no letter' 813s himself. He also has a marvelous set of ears and has always had a top notch tube based system to listen to.

First up were the EL156 amplifiers. This was the first time I've had a chance to hear them on the UREIs so I didn't know quite what to expect. These monoblocks only put out 20Ws or so of class A power and the UREIs aren't that efficient compared to Klipsch, Altec, etc horn speakers. So we were taken aback how loud and dynamic the amplifiers sounded. Bass was surprisingly deep for a single ended amplifier - in this setup I actually preferred it over my more powerful 60W Dynaco Mark IIIs. I know it sounds odd, but the Hammond output transformer on the SE amplifier is a beast and the loop feedback must help too. However there was a slight uncontrolled quality to the deepest of bass notes. Midrange and treble were both very natural sounding - quite like the 'real thing'. Dynamics were also good and only on some big drums recordings - like the Audioquest recorded Terry Evans - did the amplifier seem to run out of steam. At this point the amplifiers sounded a little blurry as the music overwhelmed the short peak power available. But the clipping never sounded harsh or terribly unnatural.

The Threshold S/500 was then fired up and allowed to settle in for a bit. We talked a bit about the pros and cons of electrostat speakers before doing any serious listening. The first cut of a Bob Dylan remaster showed an amplifier that is very neutral. As a side note my friend also remarked that the remaster sounds slightly softer than his original LP. Listening to a few cuts I noted that the top end is extended and the midrange has an inner detail that is some of the best I've ever heard. Bass control is tight as the 250Ws and low impedance really controls the large 15" Eminence woofer. On the Terry Evans cut the snap of the drum stick on the snare or tomtom was shocking and bullet fast - drums would literally hit you in the gut like the real thing. The UREIs certainly excel at reproducing the drum kit. Perhaps there was a little less 'body' than the tube amplifiers, but there was also an overall 'rightness' and coherency from the lowest to the highest frequencies. Power was never an issue either.

What amplifier is the best? Well my friend likened the EL156 amplifiers to a good film print. Very natural and beautiful. The Threshold is more like a high definition digital TV with crisp detail and bright colors. And that pretty much sums up my feelings - the tube amplifiers were natural sounding and a little less 'hi-fi' than the S/500. But they also lacked the total information retrieval that the S/500 amplifier had. As for what sounds best would be determined on what you are looking for in an amplifier. Personally in this system I preferred the S/500 for the dynamic contrasts and detail. But again I could easily live with the more 'romantic' tube amplifier. In the end I was proud of how well my DIY creation held up to the powerful competition.

Threshold FET-10/HL linestage
RAKK DAC with Phillips DVD player
UREI 813A speakers
Cardas 300B interconnects (preamp to amp)
Cardas Crosslink interconnects (DAC to preamp)
speaker cable was Weico silver coated stranded wire

Roxy Music - Avalon hybrid SACD
Terry Evans - Puttin' It Down CD
Bob Dylan - Blood on the Tracks hybrid SACD
Richard Thompson - Shoot out the Lights hybrid SACD
Buddy Guy & Junior Wells - Drinkin' TNT 'n' Smokin' Dynamite CD