Can a Amp be "timeless" and compete with todays amps?

If you are convinced that best amps can be measured, you most likely hit a goldmine of technical wisdom, although the term "smooth" might be not universal enough to define it. However, in my opinion, that is not even possible, especially because amps do not make sound on their own: the sound you hear exists in a relation to all component in the signal path.

I define 'smooth' as a lack of audible higher ordered harmonic distortion as per my prior posts to this thread. The idea that amplifiers do not make a sound of their own is false; we've been hearing these 'sounds' for the last 6 decades. Some amps are smooth and might be a bit soft in the bass, others do bass alright but are harsh in the highs. That this is so is well-known and not controversial.

I was reading through this thread and decided to post here what I had posted not too long ago on the SoundLab Owners Forum:

Audio Research VT-150SE mono amplifiers (1994) vs. Audio Research Reference 150SE stereo amplifier (2016).

"I recently purchased a Audio Research Reference 150SE stereo amplifier that uses eight (four per channel) of the (relatively new designed) KT-150 power tubes (150W pc) and the input tubes are four 6H30s.  All of the tubes are new and matched from Audio Research. Power supply energy storage: 1040 joules total for both of the channels.

The SL A3PX full-range electrostatic speakers sound excellent when driven by it using the 8 ohm taps.

Surprisingly or not, it is not “better” (whatever that means) than the two 1994 Audio Research VT-150SE mono amplifiers I’ve been using for the past twenty-five years on SoundLab speakers. I've been comparing them directly.

The VT-150SEs are rated at 130W pc and they use eight (four per channel/amplifier) of the 6550 power tubes (GE), eight 12BH7 drivers (four per amplifier) and four (two per amplifier) 6922 input tubes. It also uses tubes (two 6550s and a 12AX7) in the power supply regulation. Power supply energy storage: 420 joules for each channel/amplifier.

When comparing the VT-150SEs on SoundLab A3PX full-range ELS, the Reference 150SE tonal balance is slightly leaner (taut) upper bass and slightly more forward upper mid-range, using the 8 ohm taps on the amplifiers. Speakers are set flat (0) with treble at 12 o’clock position.

@fthompson251 

where are located? Don’t just send them to any old shop, research a lot!

we drove many hours to Rockford,IL TO A PLACE CALLED : https://soundsclassic.com

i refuse to ship my gear, I will drive my,amps to the headquarters if needed.

@williambf , your result would imply a difference in output resistance between the two models. Have you tried using different taps to see how you prefer the sound? I gleamed this from Stereophile, not sure they are your exact amplifiers.

This is 2012, may be similar.

As expected, the Ref150's output impedance varied according to the transformer tap selected. The 16 ohm tap measured 1.4 ohms at low and middle frequencies, rising to 1.9 ohms at the top of the audioband. The figures for the 8 ohm tap were 1 and 1.4 ohms; for the 4 ohm tap, they were 0.55 and 0.87 ohm

This appears to be a 1994 review:

The VT-150's output impedance was nearly 1 ohm (0.99 ohms) at any audio frequency measured at the 16 ohm tap. This value decreased to 0.56 ohms at the 8 ohm tap, and 0.3 ohms at the 4 ohm tap.

I’ve tried the three options and 8 is the one (and only one) with both amps on the Soundlabs, also what Soundlabs states.

Both amps sound excellent dynamically with a subtle tonal balance difference. 6550 vs KT150 and 1995 vs 2017 or so.