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View Full Version : Tubes vs. transistors - an amplifier designer's view from the '70s



honmanm
19-08-2010, 12:21 PM
The article on pages 6 & 7 of this old newsletter (http://www.davidsaudio.com/Gasette_Vol1_No20001.pdf)may be of interest.

In it Mr Bongiorno - who designed high-end amps first valve and then transistor based - explains why at that time (mid-1970s) transistor designs had not yet surpassed the sound quality of the best valve amplifiers. It's a good technical discussion of the relative strengths and weaknesses of the two types of device, but requires a bit of guesswork from the reader as the scanner has chopped the ends off some of the words. Of course you also need to factor in the author's bias, but at that time he was writing as the manufacturer of a very powerful transistor amplifier.

Labarum
19-08-2010, 02:42 PM
I don't think much has changed in recent years.

Valve amplifiers misbehave more graciously than transistor amps, but a well engineered transistor amp seldom does mangle the music.

The quality of a valve amp is limited by the performance of its output transformer, and by the fact that getting high nominal output is extremely expensive.

Are valvw amps really worth the hassle and the expense?

hifi_dave
19-08-2010, 06:45 PM
Some are, some aren't. Same situation as with SS amps.

Sebastien
19-08-2010, 08:16 PM
In my young hi-fi journey (I'm 29 years old), I recently switch from a tube amplifier to a transistor one. Mainly for the reliability. I had a lot of problems with my tube amplifier in 2 years. I am now happy with my hi-fi system that is here to stay:

Turntable: Rega P3,
Arm: RB300,
Cartridge: Dynavector DV20XH,
CD player: Cambridge azur 840C,
Tuner: Magnum Dynalab FT-11,
Phono pre-amp: Simaudio Moon LP5.3,
Amplifier: Luxman L-505u
Cables: the Chord, Bis Audio, Van den Hul and Nordost
Speakers: Harbeth SHL5 in rosewood!!!

Sebastien

kittykat
20-08-2010, 01:40 AM
Sweet setup Sebastien

Interesting (and very happy) to note that radio is still quite popular among Harbeth users. FM is also still quite deeply entrenched where I am. DAB hasn’t really made much inroad. There were some complaints about discernibly poor quality of DAB compared to FM. There are approximately a dozen or so FM stations where I am, 2 classical, 1 ethnic, and the balance commercial/ community. I leave it on as background entertainment when im not listening to music, but the SHL5’s have such a sweet sound (voices of announcers and classical programs) im always pulled in, to sit down and take notice. This is not good as it always means im late for something. ABC Classical has occasionally some live performance broadcasts.

Sebastien
20-08-2010, 10:04 PM
About the FM radio, we do have some dynamic and interesting one here in Montreal. Yes, they are those commercials one, but I rely on 4 very good stations with diversified programmations.

Sebastien

Drdennis
21-08-2010, 12:24 PM
We are fortunate in Boston to have WCRB that broadcasts the Boston Symphony Orchestra live.Tonight at 8:00pm EST there will be a live broadcast from Tanglewood featuring violinist Joshua Bell. If you have access to internet radio it can be found at 99.5 Classical or WGBH HD-2.
For Jazz and Classical WHRB 95.3 (Harvard University) can also be found on the internet. I do prefer to hear it broadcast through a tube tuner (Marantz 10B, or HH Scott 350b), but with a good internet set-up it can be quite nice.

Paul G Smith
13-09-2010, 05:25 PM
In the early 60s I was fortunate enough to live around the corner from a TV and Radio repair shop. It was owned by a real gent from Barbados, who allowed me to "help" from time to time in the workshop, where I learnt never to touch anything, even after it had been switched off for a long time. Not only did he repair TV and Radio equipment, which was all valve (tube) powered, he also repaired and built amplifiers for the infant Reggae sound systems. The main need for these systems was Bass. Streets full of window-shaking ground quaking bass! To this end an amplifier of 700-1200W feeding around 10-20 reflex cabinets with 15" bass drivers, each around the size of a wardrobe, was needed with a small army of people carrying the kit around from "blues" party to party!

At this time, transistors were completely out of the question, 10W into 8 ohms being the biggest available, so these monumentally huge and heavy valve amplifiers were constructed, mainly from the GEC manual of 1957. They had up to 20 pairs of KT88s in push-pull parallel, fed with 1000V at 1.4A, rectified with small mercury-arc rectifiers as there were no Silicon high power diodes or even valve diodes big enough to recify that sort of current. The whole amplifier with it's separate Output chassis, driver chassis and power supply chassis, together with a preamp chassis was mounted in a welded steel 19" rack cabinet which alone must have weighed 100Kg.

The setting up of one of these beasts was a very dangerous process. The high voltages combined with high current capability and the opportunities for explosion or fire made this process all the more exciting for this 15yr old.

I now have a system in the home, which produces more power than one of these beasts would have done, all due to silicon! No fires (yet) but clean effortless power, but aaah those memories. Now if only I had one of those amps, no, two for stereo, no, 5 for surround.....with some nice expensive interconnects.....

I think we've moved on.

KT88
13-09-2010, 07:21 PM
I've moved on, but only a bit. There are 4 pairs of KT88's running the Harbeths at my house, and they sound glorious!

Thanks for your recollection there1

Paul G Smith
13-09-2010, 07:45 PM
I've moved on, but only a bit. There are 4 pairs of KT88's running the Harbeths at my house, and they sound glorious!

Thanks for your recollection there1
From thereon I had a Leak TL12 point one (KT88's) then a Leak Stereo 30 (T), Leak Stereo70, Cambridge Audio P100 (does anyone remember them?), then back to KT88s in a Quad valve setup then Quad33 /405 and now (finally?) the Bryston setup.

kittykat
14-09-2010, 09:07 AM
Thank you Paul for sharing your very interesting experiences. My father had Leak equipment (mono I think) which he mail ordered for use in Malaya. He lived long enough to see the return of valves and being the practical man, said there was no way that he would ever use tube amps again in a hot climate. He use to mention that the transformers “leaked” due to the heat.

Paul G Smith
14-09-2010, 10:09 AM
Thank you Paul for sharing your very interesting experiences. My father had Leak equipment (mono I think) which he mail ordered for use in Malaya. He lived long enough to see the return of valves and being the practical man, said there was no way that he would ever use tube amps again in a hot climate. He use to mention that the transformers “leaked” due to the heat.
I remember there being tropicalised versions of many manufacturers equipment available to special order. I presume they used higher melting point waxes for insulation in transformers etc.