Buy tubes from Audio Research or not

I second Don c55 here. Over the years, i have purchased tubes like KT91 & KT88 from ARC and 6550C Winged C from The Tube Store and Parts Connexion for my Classic 120 monos. Biasing is very straight forward (unlike other ARC models). One biasing pot per amp. The only problem i have had when i changed the KT91 to 6550C, i did not have enough range on the pot to adjust down to .65ma. I had to replace one of the resistor beside the pot. ARC sent me so resistors of different values at no charge. Another problem i have experienced about 5 years ago, the 6550c Winged C were produced with smaller pins and fit loosely in the sockets. That issue was wide spread worldwide and an outcry ensued. Fortunately, mine are mounted vertically but those that are mounted horizontally, many people had reported their tubes sagging from their sockets. ARC use much better sockets today.

And if ARC is like cj (which I assume they are), they aren't using tube testers to select their tubes. They are testing the tubes performance in circuit, esp. for noise. One would be surprised by the reject rate.

what it seems you're paying extra for is their implied warranty to fix the amp - tube suppliers such as tubedepot (not affliated other than as a customer) offer 90 day warranties on the tubes as well

The advantage to buying ARC tubes include the 90day warranty, the fact that they have been burned in at voltage for 24hrs. so bias drifting is minimized, and are matched to the amp you need them for i.e. the biasing window of adjustment is optimized.

G

I took a chance and just bought 6 new Groove Tube 12AX7s for my sp16 from Guitar Center.

They cost $120 ($20 each) and I was able to walk in and buy them.

The tubes from ARC would have cost $200 + shipping, etc.

It worked out fine. I do not hear any noticeable difference between these and the ARC originals.

Maybe I got lucky. Either way would have worked fine I suppose.

I am referring to output tubes only

G

I had an amp sent to ARC for repair. The work was under warranty but they would not do the work unless they could re-tube it. They made $500 off a $.05 resistor.

I get that they don't want problems that bad tubes could cause but that was not cheap. Can't complain too much because I love the sound and quality, just beware that this can happen.

This is why I did not buy ARC, the warranty! VTL stands behind their products 5 yrs and with none of that bull. That would have really pissed me off. Vtl also guaranties their tubes 6 months. And they do, I had a few replaced by them no charge, just short of 6 months. Any issues, they bend over backward to satify you. That is what a highend co. is suppose to do and should do, period!

The reason you blew a resistor is because an output tube arced. When this happens the others output tubes are not far behind. Therefore, it's to your advantage to replace all the output tubes since they all have the same amount of hours on them.

Hifigeek1: I own a VS115. Couple months ago, I blew one 6550 "Winged C." As you said, I figured that the other tubes might not be far behind. Fortunately, I had a new set (2 quads) and replaced the 2 quads, checked and adjusted bias and everything seems fine. I rechecked bias 2 weeks ago and made some minor adjustments. As stated, the amp seems just fine. The question is: if the amp works and bias is correct, could the blown tube have caused damage that I am not seeing? Thanks. BIF

Yes. it's possible a resistor or resistors may have changed value. Usually when a tube arcs it takes out a resistor. If you feel the need, you might have a qualified technician make sure the resistors around the failed output tube still measure the proper resistance and that you have correct voltages at the tube socket. G

Hifigeek, just an FYI re your last post. I called ARC and spoke with a tech there. He did NOT disagree with the advice in your last post. However, he did comment that if the output tube and its "slave" (i.e., VS 115) biases within spec, and the amp otherwises operates well and sounds ok, then he thought everything was "probably" ok. I surmise from his comment that the risk of damage and grief from packing and shipping the amp (62 lbs) was greater than the benefit of changing out the resisters, especially if the amp biases ok. OTOH, there is an ARC authorized repair guy near me who I have used before. I once blew a tube on my old VS 110 and it took a resister with it. For a couple of extra bucks, the tech replaced the resister on the spot. But let me tell you, the VS 110 was a pain the butt to schlepp around, even in the back of my car.

BTW, I recently bought a vintage Crown DC300A (approx 45 lbs) off eBay for my son. Based on the pics, the amp was in mint condition. However, when I opened the box and examined the amp, it looked like the carrier played catch with the box and dropped it. The amp suffered minor cosmetic damage. Fortunately, it was going back to the factory anyway for a check-up and the damage was easily fixed. Those old Crowns were bomb proof! Anyway, I will think twice about moving my equipment around unless I really need to.

I had to repair a VS110 a few weeks ago. There not that bad to move if you have a friend handy. BTW I talk to ARC at least once a week and I tend to be a bit cautious with tube arcs etc. That being said, I understand you not wanting to shlepp your amp. I do make service calls for my customers when the need arises. Regarding the Crown DC300A, they are bomb proof.