Tired of retubing my ARC SP10

[smctigue]

I've been using ARC sourced EH 6922's. On average, I 'm getting about three months out of them before they get flakey. Generally, only the V1, V2, V9 and V10 need replacing but at $50 a tube, it gets pretty expensive.

I love this preamp but it's eating me out of house and home. Any SP10 owners out there? Anyone have any luck with 7308's? Thanks for any help.

[indy mike]

3 months of lifespan? That circuit must be pushing the tubes to their limit. 7308 variants of the 6DJ8/6922 family are referred to as 10,000 hour tubes. I've had a pair of Amperex 7308 tubes in my buffer stage for over 6 years, and they see daily use. $50 each for current production 6922 tubes is pretty high - you can pick up Amperex 7308s on Ebay for around $100- $150 a pair and get a really long lasting, well built AND great sounding tube. This thread will cover in detail what to look for when you are shopping for 6DJ8/6922/7308 tubes: http://www.stevehoffman.tv/forums/showthread.php?t=59557&highlight=7308

[TONEPUB]

You might even consider sending your SP10 back to ARC for a service/checkup. there could be something wrong, or at least marginal. It shouldn't be going through tubes like that.

I have to ask the stupid question, are you leaving it on all the time? That would greatly accelerate tube decline.

[smctigue]

It was at ARC two years ago for a full checkup. No, I don't leave it on. This preamp is notorius for tube abuse. I once bought a "premium" quad of Bugle Boys. One of them lasted less than ten hours. They did sound glorious before they incinerated.

[Kent Teffeteller]

Hi,

The ARC SP 10 is superb sounding, but they really abuse tubes beyond their limits. As a result, they have very short tube life. Why not consider another unit which is less abusive on tubes?

[indy mike]

Another possibility is to consider giving the 7DJ8/PCC88 a try. It's similar to a 6DJ8, but has a 7 volt heater (the 6DJ8 family's heater voltage is 6.3 volts). I'd check with ARC and see what they think before popping for a set of the 7DJ8/PCC88s. http://www.upscaleaudio.com/product.asp?itemid=571&action=all
http://www.tubedepot.com/nos-7dj8.html

[Plinko]

It was at ARC two years ago for a full checkup. No, I don't leave it on. This preamp is notorius for tube abuse. I once bought a "premium" quad of Bugle Boys. One of them lasted less than ten hours. They did sound glorious before they incinerated.

Wait...so is what you and others are saying is that ARC accepts this problem as part of the design? If so, absurd!

Wonder how many vintage tubes (limited supply) this thing has wasted?

[TONEPUB]

Well, obviously, they didn't accept this as part of the design, because they came out with improved products down the road....

It's all about r&d!

[RonInCRIA]

Well, obviously, they didn't accept this as part of the design, because they came out with improved products down the road....

It's all about r&d!

No.

It's about fixing the problem on the old one first.

If the unit is eating tubes, it is abusing them and it needs to be modified.

Probably this can be done.

Why it is eating tubes is the next question. I have no access to one and do not intend to buy one. But if they are cheap due to tube consumption and the basic design is workable they may be worth the candle. If someone did a mod and proved it sonically OK and not a butcher job on the unit, I bet it would make a nice article for a publication like AudioXPress. Since ARC don't advertise there maybe Ed Dell would run it as a cover story. This would apply a little Tabasco to ARC's....they would probably come up with The Factory Fix.

[RonInCRIA]

Another possibility is to consider giving the 7DJ8/PCC88 a try. It's similar to a 6DJ8, but has a 7 volt heater (the 6DJ8 family's heater voltage is 6.3 volts). I'd check with ARC and see what they think before popping for a set of the 7DJ8/PCC88s. http://www.upscaleaudio.com/product.asp?itemid=571&action=all
http://www.tubedepot.com/nos-7dj8.html

Well, if excessive heater voltage is the problem, thare's an improvement.

Probably not the problem.

Excessive B+ is probably it, or excessive current draw.