Caps

lonewolfny42 · « **on:** 11 Jul 2003, 07:57 am »

Need some help-info on caps,(not the ones you wear on your head!

) what are they - do they go bad in a SS amp ? Any info will do, thanks !

DVV · « **Reply #1 on:** 12 Jul 2003, 10:02 pm »

Quote from: lonewolfny42

Need some help-info on caps,(not the ones you wear on your head! ) what are they - do they go bad in a SS amp ? Any info will do, thanks !

Capacitors are used for three basic purposes: 1) to filter, 2) to act as "batteries", i.e. to store energy, and 3) to decouple one stage from another by blocking DC voltages possibly leaving the preceding stage from entering the subsequent stage. They are also used to create filters.

Do they go bad? Yes, they do. The larger capacity ones, such as those used in power supplies, much before lower capacity, film types. They need to be exchanged approximately every 3-5 years or so, which will depend on their quality and how long they have been under power (working) as opposed to being in non-operating power (when the equipment is switched off). If you leave your equipment on all of the time, you can count on their life span being about 30-60% longer. This is because they are kept in a constant state, avoiding switching off (not so bad) and switching on (VERY bad). Of course, this applies only to situations when you want them working in top form, otherwise they can last 20+ years before they totally die on you.

When you refer to SS amps, I assume you refer primarily to the power supply capacitors. If so, then you should know that they need to be exchange every 3-5 years, and that you would be well advised to exchange the standard types as found in regular commercial equipment (low and middle class) for the same value, same voltage but better quality capacitors. Exactly what is "better quality" will depend on who you ask, because unfortunately, there is much hype, myth and magic surround these as well as other things in audio. Ask Dan, Hugh and me and you'll likely get a similar answer. Ask others, and you'll get very different answers.

In all honesty, some of the differences are related to availability - for example, I have to bust my behind to get hold of some Elna caps easily available in the US, and Dan would have to bust his behind to get some of the Siemens Sikorel types I buy quite easily in Europe.

But that they DO influence the sound, of that there's no doubt. In my experience, Elna caps tend to give you bass to die for, but also tend to shift the accent to bass registers at the expense of higher range sound. Nichicon tends to be better balanced in my view, as do German made Fischer & Tausche, which I like to use. But for ultimate in sound, albeit at no small cost, Siemens Sikorel is the best I have ever seen and heard, which is why I use them in applications where cost is not the prime objective, but performance is.

Cheers,
DVV

Rocket · « **Reply #2 on:** 13 Jul 2003, 03:07 am »

hi dw,

i have been deliberately turning my amp off since i had it built in january (aksa), i thought leaving it on all the time would reduce the life of the components.

is it your advice to leave it on all the time?

i also have a tube preamp and would prefer to have it turned off as i thought leaving it on would reduce the life of the tubes.

thanks for your advice.

regards

rocket

lonewolfny42 · « **Reply #3 on:** 13 Jul 2003, 04:38 am »

DW, Thanks for your reply,I've got an older SS amp that I was testing and after about 40 min.'s it shuts down(protection).I'll turn it off for 15 min.'s , then back on, goes again 30-40 min.'s ,then shuts down,click ! So maybe its the caps ??

DVV · « **Reply #4 on:** 13 Jul 2003, 07:48 am »

Quote from: Rocket

hi dw,

i have been deliberately turning my amp off since i had it built in january (aksa), i thought leaving it on all the time would reduce the life of the components.

Well, ask Hugh, I think he'll confirm that leaving it on all the time will not only not hurt it, but will in fact extend its life expectancy (or that of some of its components).

Quote

is it your advice to leave it on all the time?

I never switch off my Karan, I just turn the volume down to zero. This is to avoid possible switch on thumps when switching other gear on, even if I don't have any (old habits die hard).

Quote

i also have a tube preamp and would prefer to have it turned off as i thought leaving it on would reduce the life of the tubes.

thanks for your advice.

regards

rocket

Tubes are a bit different. They have a life expectancy far shorter than solid state, only about 100 hours in top form, after which they slowly start to degrade (not die on you, of course, but their operating characteristics start to change). The 100 hours figure is a purist's view, actually many are good for 3-500 hours, and not all tubes are made the same.

But tubes I would switch off, just like you do.

Cheers,
DVV

markC · « **Reply #5 on:** 13 Jul 2003, 12:40 pm »

I have an old NAD 2140 power amp that has been turned on for the last 16 years or so. I replaced the power supply caps about 5 years ago, not because they died, just because I figured it was about time to do so. My Odyssey dual mono is on 24/7 as is my Decware tubed pre. The 6N1P tubes are cheap and also the manufacturer recommends leaving it on. Lately, I've been thinking about turning off my tubed cd player only because I have some higher priced NOS tubes in it. I just hate waiting the 1/2 hour or so it takes for the sound to be at it's best after the cdp has been turned back on.

JohnR · « **Reply #6 on:** 13 Jul 2003, 12:45 pm »

I think DVV's estimates of tube life are kinda on the low side... I understood it was more like 1000 hours for power tubes and 10,000 hours for small signal tubes. It does depend a lot on how hard they are pushed (not by audio signal, by plate voltage and current, as set by the designer).

I leave my AKSAs on all the time.

DVV · « **Reply #7 on:** 13 Jul 2003, 03:28 pm »

Quote from: JohnR

I think DVV's estimates of tube life are kinda on the low side... I understood it was more like 1000 hours for power tubes and 10,000 hours for small signal tubes. It does depend a lot on how hard they are pushed (not by audio signal, by plate voltage and current, as set by the designer).

I leave my AKSAs on all the time.

Well, I did say it was the purist's view, didn't I?

Also, I did say they wouldn't die on you, only start to change their characteristics.

Obviously, much depends on how they have been implemented in a circuit, how high or low quality are the tubes themselves, etc, etc; there are additional factrs to consider, to be sure, and this very fact makes an all-around answer impossible with any degree of certainty.

Equally obviously, low power tubes, such as those used in preamps, will last longer to much longer than high power tubes. Tubes in general don't like currents, and in preamps you don't need much current at all; assume an output signal of 3 V, about twice what is normally needed to drive any power amp to blowout, assume just 10 kiloohms of input impedane on the power amp, and all the current you need is (3:10,000) 0.0003 amps, or 0.3 miliamps.

Compare this to delivering just 10W into 8 ohms - you need 1.58 amps of current, merely (1.58:0.0003) 5,267 times more.

Cheers,
DVV

JohnR · « **Reply #8 on:** 13 Jul 2003, 03:44 pm »

Quote from: DVV

Well, I did say it was the purist's view, didn't I?

You did!

Quote from: DVV

Compare this to delivering just 10W into 8 ohms - you need 1.58 amps of current, merely (1.58:0.0003) 5,267 times more.

Don't forget the output transformer old chap! You won't find too many tubes that will deliver that much current

DVV · « **Reply #9 on:** 13 Jul 2003, 05:38 pm »

Quote from: JohnR

Quote from: DVV
Well, I did say it was the purist's view, didn't I?

You did!

Quote from: DVV
Compare this to delivering just 10W into 8 ohms - you need 1.58 amps of current, merely (1.58:0.0003) 5,267 times more.

Don't forget the output transformer old chap! You won't find too many tubes that will deliver that much current

No, you won't. Whereas that current is child's play for almost any power transistor ... even when working in a SET configuration.

Which is why I think tubes are great for preamps and far from great for power amps.

Hey, wasn't this thread about capacitors?

Cheers,
DVV

lonewolfny42 · « **Reply #10 on:** 13 Jul 2003, 09:27 pm »

Hey, wasn't this thread about capacitors? >>>>> Yes.

Rocket · « **Reply #11 on:** 14 Jul 2003, 02:09 am »

hi,

thanks for the tip.

this is probably a stupid question to you guys but is there any chance of fires occurring with audio equipment? i'd hate to come home and my house was burnt down

i told you it was a silly question.

regards

rod

lonewolfny42 · « **Reply #12 on:** 14 Jul 2003, 02:23 am »

Rocket, I don't thats a silly question.Imagine the melt down in your audio room.Vinyl,plastic,wood ,rubber,ect.Hate to think about it.But could it happen with overheating? I'd like to know that answer too!

Rocket · « **Reply #13 on:** 14 Jul 2003, 08:24 am »

hi onewolfny42,

sorry about hijacking your thread. i'm a bit worried about leaving on
my electronics as i have diy power cords and amp and if there was a fire i may not be insured.

i would prefer to leave the amp on all the time tho.

regards

rod

lonewolfny42 · « **Reply #14 on:** 14 Jul 2003, 08:35 am »

Quite all right

- but no replys to the fire question-anyone with an answer?

DVV · « **Reply #15 on:** 14 Jul 2003, 09:02 pm »

Quote from: lonewolfny42

Quite all right - but no replys to the fire question-anyone with an answer?

A fire is possible, however also very unlikely. Theoretically, a set of circumstances could appear where a component might catch a fire proper, you know, flames, smoke, all that, but in real life, that's most unlikely unless induced (e.g. by crazy loads and failing protection circuitry).

However, burnouts, which produce the more or less same effect, black patches on the circuit boards, charred components, etc, are possible and do happen, however rarely. The difference is not too much smoke except from one or more burnt out components, nasty smell which lets you know what just happened, some bluish smoke and lots of adrenalin and most unseemly language, very politically and sexually incorrect.

Typically: "!@#$%^&* Japanese !@#$%^&*!!!"

Cheers,
DVV

randytsuch · « **Reply #16 on:** 14 Jul 2003, 09:42 pm »

Quote from: DVV

A fire is possible, however also very unlikely. Theoretically, a set of circumstances could appear where a component might catch a fire proper, you know, flames, smoke, all that, but in real life, that's most unlikely unless induced (e.g. by crazy loads and failing protection circuitry).

Hi DVV,
Are you talking solid state, or tubes?
With SS, I would agree with you. With tubes, I remember one guy, I think it was harvardian, who had a tube amp catch fire. So, if I had tube amp, I do not know if I would leave it on 24/7. I used to have a tube preamp, and I left it on without worrying about it.

Randy

Guan · « **Reply #17 on:** 15 Jul 2003, 02:30 am »

Until recently I was running a Mesa Baron which ran hot, hot, hot (12 6L6 power tubes) and I always had an uneasy feeling when I left home without turning it off.

Now that I've switched to a SS amp that I leave on 24/7 and it merely runs comfortably warm, the peace of mind is simply wonderful!

DVV · « **Reply #18 on:** 15 Jul 2003, 07:35 am »

Quote from: randytsuch

Hi DVV,
Are you talking solid state, or tubes?
With SS, I would agree with you. With tubes, I remember one guy, I think it was harvardian, who had a tube amp catch fire. So, if I had tube amp ...

Mostly SS, Randy. Tubes usually work in pure class A, which means their heat dissipation is rather high, causing much heat to be produced. Therefore, such items, be they audio or something else, are best not left on with nobody around.

Also, proper ventilation must be had at all times, with all equipment generating heat.

Cheers,
DVV

lonewolfny42 · « **Reply #19 on:** 15 Jul 2003, 07:40 am »

DVV, I've got a 100 watt Krell ksa-100,class A solid state . Gets REAL hot,enough to keep my audio room toasty in the winter,and warm in the summer!