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Cary SLP 05 - When To Replace Tubes?

Hi

I have a Cary SLP 05 preamp. recently, I changed some power cords on source components and added a USB and SPDIF reclocker. The overall result was the bass became resonant and boomy, so much so that my ears ring after prolonged listening. It could be a power cord mismatch but i have a feeling power cords do not alter the sound that much.

I suspect it may be the tubes getting old. I use NOS RCA Grey Glass GT’s for the quad and Sylvania GT’s in the balanced positions. They are about 5 years old with playback time of 5 hours every weekend (estimated 1,250 hours of use) and measured in the mid to high 90’s when I purchased them. I do not have a tube tester.

Does anyone know what the lifespan for these tubes are and if it’s time for a replacement set? I am guessing if it is time’s up, I’ll need to replace all 6.
mikey8811
mikey8811 OP
259 posts
 
My memory is hazy. Which tubes do I match?

1&2 - left & right channel positive phase gain (1st 2 tubes on front row from left to right)

4&5 - left & right channel negative phase gain (1st 2 tubes on back row from left to right)

3&6 - left & right channel balanced input buffer (3rd column, 2 tubes from front to back)

Correct?

joey_v
663 posts
 
I believe that is correct. 
brf
1,715 posts
 
The best tube compliment/combination will vary based on the mode of operation.

If single ended from input to single ended output, you only need to concern yourself with tube positions #1 and #2.

If you are running single ended inputs to balanced output, you need to concern yourself with tube position #1, 2, 4 and 5

If you are running balanced inputs to single ended output, you need to concern yourself with tube positions #1,2,3,6

Balanced in to Balanced output you need to concern yourself with tube positions #1,2,3,4,5,and 6

Tube positions 7 and 8 are for the headphones.

jond's avatar
jond
5,780 posts
 
So just for fun maybe before you start changing out all your tubes try removing the new power cords and USB/Spdif reclocker and see what happens? You can do this immediately and get results plus it's free. Good luck!
elevick
2,636 posts
 
I would expect 5000 hours.  You need to get them tested.  The rectifier will last even longer.
Blame the sound on the power cord. They do need break in time.
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