plight of a consumer

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myriad
Ist häufiger hier

#1 erstellt: 14. Jan 2005, 07:01

Last week the right 12AU7 tube of my Cayin blew off resulting in no sound from the right channel. The Soundsmiths was instantly informed through it's Kolkata dealer and moreover i had a personal talk with their techie guy, Mr. Vaz. I explained him that the right end tube which is 12AU7 is not working. He assured me a quick replacement.
Yestersay, from them, i received a pair of 12AX7 instead of 12AU7 . I soon called up Soundsmith.. there was some Mr. Vishal at the other end. He said that it's no problem using 12AX7 in place of 12AU7. I did the same but noticed the sound didn't have same fluidity as before. It was little grainy in the highs. Then in the evening i contacted Mr. Vaz who also echoed the same story as Mr. Vishal that it was no problem using 12AX7 in place of 12AU7 but when i told him that the sound was grainy in the highs he said that the tubes will take some time to settle down and after few days u will find the sound turn smooth.
At night i logged on to AudioAsylum and read that it was unadvisable to put 12AX7 in place of 12AU7. It said 12AX7's have around ten times more gain than 12AU7 and it could lead to blow tubes and even the amp in some cases.
Now i have taken out 12AX7's and put back 12AU7's and have asked my dealer to get me 12AU7's. He said he will talk to Soundsmiths and arrange the same as soon as possible.
I wanted to narrate this long story just to make u consumers aware of the shoddy practice of our countries audio distributors.

Manek
Inventar

#2 erstellt: 14. Jan 2005, 07:38

Its best to put the original tube back so that your sound timbre is the same in both channels. Ofcourse you may also need to re-bias your amp once a tube is changed. If I remember correctly, the cayin does not have auto biasing feature so a manual biasing procedure maybe in order as well. Check that with your dealer/soundsmiths as well.

Manek.

Prithvi
Stammgast

#3 erstellt: 14. Jan 2005, 12:24

Hi! Myraid,
You cannot just plonk a 12AX7 inplace of a 12AU7, Just call up SOUNDSMITHS and get the correct tube and yes you will have to rebias the tube, better to get two tubes and replace them rather then just one. Actually you can get the tube in Kolkatta go to the electronic market and ask for tubes.

Rgds

Prithvi

Manek
Inventar

#4 erstellt: 14. Jan 2005, 12:42

In such cases , its great to have auto-biasing amps.

BTW, do you know how to bias your amp ? do you know which pots to fiddle with ? do you have a meter ? or will the dealer do it for you ?

If the amp is going to be re-biased then I guess replacing one tube of the "same type and make" is OK, provided the baising is done correctly. Putting in two "matched" tubes would be apt so you can keep the older one as a spare in case of any eventuality again.

manek.

myriad
Ist häufiger hier

#5 erstellt: 15. Jan 2005, 06:22

Yesterday i went to hunt down tubes in the local market and astonished to get a pair of Brimar 12AU7 for Rs.35/- each.
Now my amp is back again, alive and sounding better than before.
Regarding re biasing... my amp doen't have external biasing pots. I do have a voltmetre but didn't want to open the underlid and fiddle with it. So i sent a letter to Paul Gryzbek who is a US Dealer for Cayin. He sent a prompt reply and this what he says,

"Great Hearings from you!

The fixed bias stock version does not require biasing. Just need to buy matched EL-34'sand plug them in. Small tubes do not have adjustments.Your BrimarU's are excellent.The X7 does function fine in the U position-but the sound is bit brighter,less bass.

Hope your amp provides years of enjoyment. I no longer sell Cayin products. I now have my own house brand builtto my specification.

Paul"

Manek
Inventar

#6 erstellt: 17. Jan 2005, 09:00

myriad,
just shows that the US dealer knows a bit about the product he is selling.....quite the opposite in your case in India i'm afraid , but not at all surprised. This happens to a lot of Indian consumers currently.

manek.