[dngl]

yeah man, Melos amps are for lazy people because they have three inputs and don't require much maintenance. They do chew up tubes, I hear...

 

[Dusty Chalk]

I just wanted to add two things to my post:

- another problem that you may run into is that you may have to bias the tubes, if the amp is not auto-biasing. But I'm not sure there are any headphone amps that need biasing -- the RKV, the MG Head, MF X-CAN all do not.

- Welcome!

 

[Calanctus]

RickG,

At the risk of going a bit off topic: your tag line is 'Electrostatic Elvis'. How do tube amps sound with electrostatic phones? I've got a pair (Koss ESP/950s) and don't like the brightness (fatiguing), but maybe I should not write off electrostats just yet, if a tube amp can restore some smoothness.

Tomcat,

Thanks for your previous recommendation of the Beyerdynamics. The Earmax Pro is indeed very high on my list.

 

[Morse]

Hi Calanctus!

In my honest opinion you should look at the issue of valve lifespans in terms of hours of operation, rather than asking for a set figure ("Need I replace them every x number of years?"). Also, it really depends on how you use your hifi. Here are some examples of good ways to kill your valves quickly (i.e. if you want your valves to last, DO NOT DO THESE THINGS).

1. Short cycling - if you like to turn your hifi on and off many times during the day, you will wear out your valves much faster. This is because the high voltage peak hitting the cold valve will wear away at the thin outer coating on the cathode. Eventually the coating on the cathode will be damaged to the point that the valves emissions drop, and it's time for a new valve.

2. Tapping on a hot valve - some people like to tap on their valves while they're running to test for "microphonics". DON'T DO IT! You can easily induce microphonics (and other damage) in a healthy valve by doing this since valves are more delicate when hot.

3. 24/7 operation. This is the opposite of valve killing strategy number 1; some people go overboard and like to run their amps continuously. Go check the data sheets for various valves; frequently a manufacturer will have 2 sets of specs, CCS ("Constant Commercial Service") and ICAS ("Intermittent Commercial and Amatuer Service"). The CCS specs for allowable voltages and currents will always be lower than the ICAS spec, as will the lifespan (if rated). Thus, if you run a hifi that was designed around ICAS standards in a CCS manner, you can expect to dramatically shorten the lifespans of your valves.

As far as an hour figure for valves, it can be anywhere from DOA to 100,000 hours (that would be for the creme de la creme of 12AX7's - the Telefunken, under ideal conditions). Figure around 2,000 to 3,000 hours of operation for output valves and a bit more for the small signal valves, and you probably won't be too disappointed. The last valve I had die an ugly death on me was a cheapie Chinese EL34 that died somewhere around 800 hours of operation.

As far as your question about sourcing replacement valves, you can buy valves from many different places online; you could start looking at Parts Express at http://www.partsexpress.com/
and Triode Electronics at http://store.yahoo.com/triodeel/index.html For whatever it's worth, I've bought quite a few things from both those places with no problems yet (knock on wood...).

Anyway, good luck and Enjoy Your Music!
Morse

 

[Tuberoller]

Quote:

Originally posted by Morse Hi Calanctus! In my honest opinion you should look at the issue of valve lifespans in terms of hours of operation, rather than asking for a set figure ("Need I replace them every x number of years?"). Also, it really depends on how you use your hifi. Here are some examples of good ways to kill your valves quickly (i.e. if you want your valves to last, DO NOT DO THESE THINGS). 1. Short cycling - if you like to turn your hifi on and off many times during the day, you will wear out your valves much faster. This is because the high voltage peak hitting the cold valve will wear away at the thin outer coating on the cathode. Eventually the coating on the cathode will be damaged to the point that the valves emissions drop, and it's time for a new valve. 2. Tapping on a hot valve - some people like to tap on their valves while they're running to test for "microphonics". DON'T DO IT! You can easily induce microphonics (and other damage) in a healthy valve by doing this since valves are more delicate when hot. 3. 24/7 operation. This is the opposite of valve killing strategy number 1; some people go overboard and like to run their amps continuously. Go check the data sheets for various valves; frequently a manufacturer will have 2 sets of specs, CCS ("Constant Commercial Service") and ICAS ("Intermittent Commercial and Amatuer Service"). The CCS specs for allowable voltages and currents will always be lower than the ICAS spec, as will the lifespan (if rated). Thus, if you run a hifi that was designed around ICAS standards in a CCS manner, you can expect to dramatically shorten the lifespans of your valves. As far as an hour figure for valves, it can be anywhere from DOA to 100,000 hours (that would be for the creme de la creme of 12AX7's - the Telefunken, under ideal conditions). Figure around 2,000 to 3,000 hours of operation for output valves and a bit more for the small signal valves, and you probably won't be too disappointed. The last valve I had die an ugly death on me was a cheapie Chinese EL34 that died somewhere around 800 hours of operation. As far as your question about sourcing replacement valves, you can buy valves from many different places online; you could start looking at Parts Express at http://www.partsexpress.com/ and Triode Electronics at http://store.yahoo.com/triodeel/index.html For whatever it's worth, I've bought quite a few things from both those places with no problems yet (knock on wood...). Anyway, good luck and Enjoy Your Music! Morse

All excellent points.You have a real knowledge and your explanations are very easy for a novice to understand.what is your backround?

 

[Morse]

Hi Tuberoller and thanks for the compliments! To answer your question, I’ve been an electronics nerd for over 20 years now (I won’t tell you how many years over 20!). Currently I'm working on a doctorate, thus I occasionally teach (and bore!) roomfuls of people at a time to earn my keep.

Morse

 

[Born2bwire]

Quote:

Originally posted by Morse Currently I'm working on a doctorate, thus I occasionally teach (and bore!) roomfuls of people at a time to earn my keep.

Please tell me you're going to avoid the UIUC Physics department if you're going to be that boring.

 

[Morse]

Not a problem Born2bwire! However, I suspect that boring classrooms full of biology students who don't want to take physics but need it to fulfill their geneds goes with the job.....

Peace be with you!
Morse