Audio Research Pre-Amp advice

daveteauk

... May I ask why you change the 6550 at just 2k hrs? What part does the 6550 play in the power supply? ...

The 6550 is critical to the power supply and 2,000 to 2,500 hours is about all you can expect from it, and least in my Ref5SE and Ref Phono 2SE.

@cleeds - thanks, but what exactly is 'critical'? What part does it play - my Ref3 seems to use SS rectification, so is the 6550 the supply voltage for the 6H30 in the PS, or does it do something else? 2000hrs seems a very very low figure for replacement - what do you experience, in SQ, after that time?

daveteauk

... what exactly is 'critical'? What part does it play... 2000hrs seems a very very low figure for replacement - what do you experience, in SQ, after that time ...

The 6550 tube in ARC Ref5/Ref 6/Ref phono is in the power supply. It will sonically degrade after a few thousand hours, and can fail outright before 3,000 hours, ime. You really don't want that to happen. If the cost or frequency of replacing vacuum tubes is a great concern for you, it's likely that ARC Ref preamps aren't your best choice.

@cleeds is correct, we both own the same 2 ARC components that utilize the 6550 in the power supply. Im not in front of my manual but my memory is the ARC recommendation for change interval on the 6550 is 2K hours. i change the 6550 religiously. My comment about NOS USA New Jersey Tung Sol blackplate was very specific as i worked w Andy at Vintage tube services in Michigan USA to tease out the best 6550 for the 5se AND importantly my system and tastes. i know they are “ expensive “… But not really when considering a Koetsu Urushi at $6k has about a 1,200 life…. $ or ¥ or € or £ is all relative…. Frankly a very reliable supplier of the critical 6550 is ARC themselves…stringent grading and burn in and excellent packaging. i keep 2 on hand as my phono use same.

@daveteauk I am not sure how you reached the conclusion i’ve not changed the 6H30’s. 

Best to all in music….

PS this morning i’m listening to a nice system w 20 NOS tubes in the LP playback chain including 5 x Mazda in the Phono, 4 x Orange Globes in the Line… and mostly Mullards in a not so stock… 1961 MC-240… life is fun….

Tomic601- that‘s awesome!

I get ARC select tubes from Upscale Audio.  They sound good.  I have been changing the 6550WE at about 1500 hours and the 6H30pi tubes at 3200 hours.  I notice a nice uptick in the sound at that point.  Using a Ref 5SE and Ref 2SE Phono.  I stocked up on tubes in 2020.  I noticed today tube prices are double what I paid 4 years ago- and I need to restock again soon.  

Got my first ARC preamp in 1988, a used SP-6b that I then had modified with upgraded components.  Used it for 14 years.  Got an SP-15 that I used for 18 years.  I sent it in for refurbishment by ARC in 2004.  And now the Ref 5SE/Ref 2 SE phono.  Good stuff.  Love having a remote control now that I am old and decrepit.