hqyy@vax5.cit.cornell.edu (12/28/90)
Hello,
On the subject of leaving components turned on as warm improves
sound quality: inthe case of transistor (or MOSFET) amps or pre-amps
(such as the mentioned Threshold), this is recommended as the surges from
turning on and off will tend to damage components and also since the
parts inside the component will reach and stay at a thermally stable
environment. In the case of tube amps or pre-amps, use your judgement:
if left on, tube life will be considerably shortened and you also risk
damage from voltage spikes.
I am not quite sure about leaving CD players left on but I do know
that passive components (such as decoders) should be left on while active ones
(such as CD transports) are better left off.
satish nairjfw@neuro.duke.edu (John F. Whitehead) (12/31/90)
In article <8587@uwm.edu> hqyy@vax5.cit.cornell.edu writes: > On the subject of leaving components turned on as warm improves >sound quality: inthe case of transistor (or MOSFET) amps or pre-amps >(such as the mentioned Threshold), this is recommended ... > >satish nair There was recently an article in a computer magazine (PC Magazine?) that discussed the pros and cons of leaving electronic equipment on for long periods of time. The conclusion is that you will be able to find an "expert" who will support your decision whichever way you go. Leaving equipment on does protect it from power-up and -down surges and allows for a constant temperature. This keeps sensitive components (especially ICs and solder connections) from continually expanding and contracting which may be stressful to the components (one of which is your wallet :-). Most electronic equipment is made not to get "tired" from being left on and should have no adverse effects from being left on. But it also is a waste of energy and a source of potential problems in the case of a black- or brown-out. Make sure that you at least have a spike protector. For myself, I compromise. For my computer, I leave it on 24 hours a day except when I know I'll be away from it for more than a couple of days. I often turn off the monitor to save energy. For my stereo (solid-state) I only leave it on if I plan to use it again within a few hours. Remember to always turn your volume all the way down before turning the power on or off to *any* of your components, or if you aren't listening to anything!!! John Whitehead Internet: jfw@neuro.duke.edu Department of Neurobiology jfw@well.sf.ca.us Duke University Medical Center Bitnet: white002@dukemc Durham, North Carolina
sbhattac@sales.gba.nyu.edu (12/31/90)
In article <8587@uwm.edu> hqyy@vax5.cit.cornell.edu writes: > On the subject of leaving components turned on as warm improves >sound quality: inthe case of transistor (or MOSFET) amps or pre-amps >(such as the mentioned Threshold), this is recommended as the surges from >turning on and off will tend to damage components and also since the >parts inside the component will reach and stay at a thermally stable >environment. Some designs take account of this. Borbely's amp designs in Audio Amateur did just that. He chose bias for the Hitachi MOSFETS so as to minimize temperature effects. Given the device characteristics that I have seen, that design choice should be highly successful. Each MOSFET conducts about 100 ma quiescent current. Of course, this has limited applicability to amps where the designer chooses much higher quiescent current, as in class A amps. ---------------------------------------------------------------------- Shankar Bhattacharyya, Information Systems, New York University sbhattac@sales.gba.nyu.edu ----------------------------------------------------------------------
ag@sics.se (Anders G|ransson) (12/31/90)
>>>>> In article <8587@uwm.edu>, hqyy@vax5.cit.cornell.edu writes:
hqyy> In the case of tube amps or pre-amps, use your judgement:
hqyy> if left on, tube life will be considerably shortened and you also risk
hqyy> damage from voltage spikes.
I used my judgment to effect of a "burnout" of one my modified
Dynaco Mark VI. It is now repaired and I got the pair up for
sale.
The difference between warmed up and cold amplifiers were with
this equipment really great, that's why I left them on.
But, there is the consideration of the tubes lifetime as well.
I read somewhere that the lifetime in hours were somewhat
prolonged by never turning the amp. off but then again they're on
so many more hours so you'll have to replace the tubes more
frequently. In Sweden, at least, that's an affair costing about
2000 SEC, (appr. 400$).
Could someone give an estimate what a pair of these mark VI
would cost in U.S.A. How many of them were sold?
For information I can tell that I paid 10 000 SEC for my pair.
(aprrox. 1 200 $).
I guess that was a bit too expensive even for the Swedish
market.
--
name(!): Anders G|ransson, (Not a very serious character).kenw@arcsun.arc.ab.ca (Ken Wallewein) (01/02/91)
If manufacturers (esp. tube-type power amp) intended that their equipment be left turned on, surely they would provide some sort of stand-by mode; reduce or remove B+ voltage, drop heater voltage to about 5 volts, etc. Such changes can keep the equipment essentially "warmed up", while greatly reducing stress and succeptibility to AC supply fluctuations. These measures have been used in other applications in the past. /kenw
ph@ama-1.ama.caltech.edu (Paul Hardy) (01/02/91)
In article <8587@uwm.edu> hqyy@vax5.cit.cornell.edu writes:
On the subject of leaving components turned on as warm improves
sound quality: inthe case of transistor (or MOSFET) amps or pre-amps
(such as the mentioned Threshold), this is recommended as the surges from
turning on and off will tend to damage components and also since the
parts inside the component will reach and stay at a thermally stable
environment. In the case of tube amps or pre-amps, use your judgement:
if left on, tube life will be considerably shortened and you also risk
damage from voltage spikes.
With tubes, you can use a Variac to keep them at, say, 25 VAC and turn
this up to 120 VAC for listening. This gets around the power-on spikes,
and keeps the other components (e.g., caps) warmed up to some degree.
Anyone know of a good commercial source for Variacs?
--
---
This is my address: ph@ama.caltech.edu
This is UUCP: ...!{ihnp4,uunet}!
This is my address on UUCP: ...!{ihnp4,uunet}!caltech.edu!ama!ph
Any questions?
"Does Emacs have the Buddha nature?" --Paul Hardyjhess@orion.oac.uci.edu (James Hess) (01/04/91)
In article <8634@uwm.edu> ph@ama-1.ama.caltech.edu (Paul Hardy) writes: > >With tubes, you can use a Variac to keep them at, say, 25 VAC and turn >this up to 120 VAC for listening. This gets around the power-on spikes, >and keeps the other components (e.g., caps) warmed up to some degree. > >Anyone know of a good commercial source for Variacs? > Any electronics supply house. TV and stereo servicers use them all the time. [Variac is a trademark of GenRad; you'll want to ask for a variable autotransformer. -tjk]
chowkwan@priam.usc.edu (Raymond Chowkwanyun) (01/08/91)
In article <8634@uwm.edu> ph@ama-1.ama.caltech.edu (Paul Hardy) writes: >With tubes, you can use a Variac to keep them at, say, 25 VAC and turn >this up to 120 VAC for listening. This gets around the power-on spikes, >and keeps the other components (e.g., caps) warmed up to some degree. > >Anyone know of a good commercial source for Variacs? > I have a Tice Variac. Tice warns against trying to use the variac to run tubed equipment at less than 100% of line voltage. It has this big dial on the front that you turn manually to bring the voltage up from 0 to 100% of line. Then you have to quickly flip a switch to bypass the variac altogether. $700 for about 10 seconds of use each day. I wonder if it wouldn't be more cost-effective to just replace the tubes as they wear out. If you're really interested, Audio Advisor sells them. (800) 942-0220. -- ray
ph@ama-1.ama.caltech.edu (Paul Hardy) (01/10/91)
In article <8756@uwm.edu> chowkwan@priam.usc.edu (Raymond Chowkwanyun) writes: > I have a Tice Variac...$700...I wonder if it > wouldn't be more cost-effective to just replace the tubes > as they wear out. > > If you're really interested, Audio Advisor sells them. > (800) 942-0220. > > -- ray Tice has very nice products, but I'm put off by their prices. Someone wrote a letter to the editor of Sterophile or TAS a couple of years ago or so in response to a Tice line conditioner review, and pointed out that instead of spending $2000 on line conditioners, you could have the electric company install a separate mains line for your audio equipment in your home for $1000 with better results. I heard about the Tice power-up product before they began selling it. Then, it was going to have some electronic timing gizmo for the 10 second power-up sequence. Even with that (what could it possibly have been at that price?) I personally thought their cost of $700 was way too high to buy one. I think Tice is right though: you shouldn't run hungry equipment at 100% from a Variac. But a simple make-then-break switch could be used in parallel with the Variac after the dial's been brought up to 100%. I have two VTL 70/140 Watt Monoblocks (70 Watts in triode mode, 140 in tetrode mode -- upgrade from the 60/120s). I run them in Class A triode mode (70 Watts is fine for me in my apartment, even with my inefficient Maggies, and the sound is beautiful) and decided to leave them on all the time. The power consumed can't be too great; my electric bill is under $40 a month, and I have various modern conveniences (refrigerator, a couple of computers & random electronic gear, electric heat, etc.) I listen to the equipment in the morning and evening, and sometimes during lunchtime, and it could be that three power-ups per day is far more damaging than leaving it on all the time anyways. Time will tell! I suppose DC high-rail power supplies would be even less detrimental to the tubes. These amps do have DC heater voltage supplies. --Paul -- This is my address: ph@ama.caltech.edu This is UUCP: ...!{ihnp4,uunet}! This is my address on UUCP: ...!{ihnp4,uunet}!caltech.edu!ama!ph Any questions? "Does Emacs have the Buddha nature?" --Paul Hardy
wmartin@STL-06SIMA.ARMY.MIL (Will Martin) (01/21/91)
From: ph@ama-1.ama.caltech.edu (Paul Hardy) >Tice has very nice products, but I'm put off by their prices. Someone wrote >a letter to the editor of Sterophile or TAS a couple of years ago or so in >response to a Tice line conditioner review, and pointed out that instead of >spending $2000 on line conditioners, you could have the electric company >install a separate mains line for your audio equipment in your home for $1000 >with better results. Actually, at least here (St. Louis) the last time I checked, the electric company would run a second mains line to your premises for free. They make their money off the meter readings generated by that line (even if you use no electricity, the minimum billing gets them a hefty profit). I had been thinking about putting a fully-equipped workshop in my garage, which is separated from my house by 50+ feet but which is close to the power lines running down the alley. Seemed far more sensible to avoid digging up the yard to replace the existing low-capacity house-to-garage buried wiring conduit, and just put in a completely new service dircet to the garage, so that's why I asked. (Never did it; maybe at some future date...) Of course, the homeowner pays for the electrician to do everything on the house side of the meter, so maybe that's the $1000 cited above. But a do-it-youselfer could save a lot by doing all the rough wiring. Of course, I guess an audiophile would have to use silver wire... :-) There go the savings... Regards, Will