Confusing about matching tubes in ref40, pls advice.

[TOGA]

Originally Posted by microstrip

Toga, I measured all the 6h30 tubes I got for my REF40 and selected very close matches in transconductance for the amplifying tubes (those immediately after the volume control) and used the remaining as cathode followers or in the power supply. I discarded all tubes that had differences in trans conductance values between triode sections of the same tube of more than 5%. Most of them were closer than 2%.

Thank you.. I really have to study more about this. Frankly, tube technical terms here are so new to me. Toga

Is this correct according to your words?

[TOGA]

Originally Posted by 2fastdriving

I'm no expert at this, but on the ref75, there is a separate bias setting for each kt120.

Ok then I was wrong here, you are correct. In this case we can use four non-matched pair KT120 for Ref75 right? As we can individually bias each tube. Again, for me, tubes and turntable experience and knowledges are almost zero. Just love the sound. Toga

[veerapaneni]

ARC Says Ref 40 Needs the following tubes. You don't need Matched tubes as per thier requirement. But you can always buy Matched Tubes if you want .

Tube Complement
(8)-6H30P dual triodes, plus (2each) 6550C and 6H30P in power supply.

[Barry1]

I have 2 sets of ARC supplied 6h30 tubes including two pairs of power supply tubes and two sets of the octets in the line stage. I also have one set of 6550WEs.

Maybe Micro can tell us exactly what voltages these tubes are run in the Ref 40 circuits. I'd sure like to know as my attempt to measure voltages in curcuit was not successful and I could custom match them if I knew.

I plan to test all these tubes on an Amplitrex AT1000 this weekend at the testers "default" plate and grid voltages for the 6h30s. I already tested the pair of 6550WEs that are for the power supply and ran plate and bias voltage characteristic curves on the AT1000. The plotted curves for the pair matched well within 2%. A pair of matched tubes from a well known US vendor was not nearly as closely matched.

One matched set of tubes is hardly a representative sample, but I was impressed by ARCs tolerances for the 6550s compared with the tube dealer's. I'll share more when I complete the testing and we'll get a better idea of ARC's matching services.

[TOGA]

Ok, to make life simpler , I should just order a set from ARC and forget about aftermarket tubes.
ARC tubes seems good enough.thanks

Toga

[TOGA]

Oh my god.. A set of matched tubes for REF 40 Total 12 tubes matched from ARC factory. Dealer told me $1,000 !!!! Toga

[TOGA]

How about this claimed to be very good sounding?
Is it worth 50% premium?
Toga

[Coopersark]

Originally Posted by TOGA

How about this claimed to be very good sounding?
Is it worth 50% premium?
Toga

Toga --
I use these in my CD8 player and Ref5 SE preamp. I do not think that there is any difference in the sound. The Tube Store also told me no sonic difference or improvement. I have been told that they last longer, but will still change them out at around 2,000 hours. It is cheaper to change tubes than to repair Audio Research equipment! Next go around I will use the standard 6550C's in my Audio Research gear. I prefer the sound of the 6550C to the 6550WE and am happy to pay the premium for those, but to get the Black Sable level is a waste, at least for me. This is a power supply tube, not a signal tube in both of our cases. Good luck with whatever you decide.
Best wishes,
Rob

[TOGA]

Thanks a lot, that will save me big $$.
But the supplied 6550c were SED's.
But the standard one.

But I will not pay >$1,000 for factory tubes set. That s too much.

Toga

[Coopersark]

Originally Posted by TOGA

Thanks a lot, that will save me big $$.
But the supplied 6550c were SED's.
But the standard one.

But I will not pay >$1,000 for factory tubes set. That s too much.

Toga

I agree with you. Check out tubedepot.com. I have purchased my tubes from them on numerous occasions and have always been very pleased.