Do I need expensive vacuum tube power amplifiers?
No!!!!! AUDIO SPLENDOR can save you a lot of money by equalizing your speakers much better than using the high output impedance of expensive,
low-feedback, vacuum tube amplifiers. Instead buy low distortion semiconductor amplifiers that have a lot of feedback and far more power output.
During my 60 years of designing circuits I designed a lot of vacuum tube, transistor, and switching power amplifiers and know how each performs. In the
1950's I designed the lowest distortion vacuum tube amplifier ever, the Krohn-Hite UF-101. It was rated at 50 Watts, 0.005% total harmonic distortion, 50
dB of negative feedback, and it sold in small quantities as a laboratory instrument for 20 years. Today I wouldn't take a vacuum tube amplifier as a gift.
Why?
What you are really buying is not quality amplification but a high distortion equalizer. The lack of feedback in many of today's tube amplifiers gives theamplifier high distortion and a high internal output impedance, typically in the range of 1 to 5 ohms. At some frequencies such as the fundamental coneresonance, and crossover frequencies between drivers, the load impedance of the speaker rises. The voltage divider effect delivers more signal to thespeaker terminals at these frequencies. With some amplifier-speaker combinations the effect on frequency response is very pleasing.
This load impedance effect was epitomized in the July, 2004 Stereophile review of the world's most expensive amplifier, the $350,000/pair Wavac SH-833,by Michael Fremer with measurements by John Atkinson, page 73. The curves clearly show up to 2 to10 dB of bass boost at 80 Hz depending upon theload impedance. The measured distortion is shameful for even the cheapest amplifier. A vacuum tube amplifier should really be regarded as a nice pieceof furniture with wires, that glows in the dark. Use a real equalizer to improve the frequency response of your speakers!
Equalizing your speakers is not enough. Any fixed frequency response system may optimally balance the tone on about 1 in 500 pieces of availableprogram material. You need really flexible multichannel program equalization to balance all the rest.
In my own sound system for 30 years I used Phase Linear 400 power amplifiers that I redesigned for lower noise, -115 dB re 200 watts, and reduced biasdrift. The 34 channels each drive 1 woofer, 1 mid-range horn, or 9 or 12 of the 30 tweeters in each 13 foot speaker horn. With the 4-way electroniccrossover the equivalent sound level available is that of a single 20,000 watt monoblock. Before purchasing these amplifiers I compared one with myKrohn-Hite UF-101 Ultra-Low Distortion Power Amplifier. The sounds were identical except that the Phase Linear 400 played louder before clipping.
In 2004 after tiring of repairing the Phase Linears whose transistors suffered thermal fatigue, I replaced them all, purchasing 19 QSC SRA1222 dual 200 watt amplifiers. I chose these amplifiers, after measuring one unit, for their 200 watts/channel, (all my speakers can handle), low internal impedance dueto high feedback, flat frequency response, low distortion, low noise (6 dB worse than my Phase Linears), high slew rate, switching power supply,automatic gain reduction during clipping for reduced distortion, 3.5 inch rack panel size, 22 lb. weight, very low fan noise, and 3-year warranty. They costunder $1000 each and for somewhat more money QSC offered up to 1800 watts/channel into 2 ohms in the same size. I cannot detect any change in thesound. In 6 years of operation at 70 hrs/week, none have failed.
That is the sort of amplifier I suggest for you and there are plenty of other good amplifiers from other manufacturers in the professional area. And forgetexpensive cables. They are inaudible furniture.