Hi again,
Frankly, I think this topic has run its course. I am in contact with the US distributor (a very nice guy, indeed).
The reason for starting this topic was simply to question Cayin's use of a 5AR4 in the A70T. My amp is three years old, but the current crop of 55W versions have exactly the same 5AR4 implementation. So it is valid to bring this issue up. Regardless of our geographical location, this is a worthwhile topic on any internet forum. And I think that it quite informative to discuss these things, both for the techies, casual consumers, sales and distributor folks, and the manufacturer. It provides a little insight into the thinking of the manufacturer.
Cayin's only explanation for this tube is that it "sounds better". Well, they are in good company with this opinion. Kondo makes some of the most expensive and highly regarded amps on the planet, and I have heard that he shares this opinion (I can't verify this though
). And the US distributor told me that people who can not hear the difference between a Sovtek and Mullard 5AR4 in this amp don't listen very well - which must include me
. So there are a number of people who think this design has merit. I differ with that opinion. I believe that sonically it makes no difference at all.
There is a lot of magical thinking in audio. You even find it among very technically savvy people. My final thoughts on this are that either Cayin truly believes that this design improves the sound (against all technical logic - and my informal blind test) or they put the tube on the amp just because it looked nice. The latter explanation doesn't make much sense because it cost money to put this tube in the amp - and I doubt there are many people who would base their decision to buy this amp on the presence or absence of a rectifier tube. So I am inclined to believe that the folks at Cayin indulge themselves in a bit of magicism.
And finally, I will state that despite this issue with the 5AR4 and the auto-bias issue (which is fixed) this Cayin product is exceedingly fine, both in terms of sound and build quality. I would not discourage anyone from purchasing this amp because of the 5AR4 setup. In fact, one of my listening buddies wants exactly this amp after hearing it this weekend. I would, however, strongly discourage people from spending money on expensive NOS 5AR4 tubes though.
I had thought about trying out the 55W version. But after getting the bias set properly on the Class A version, I have a hard time imagining that the 55W version would be any better (despite two distributors insisting that the 55W version is better). Plus, I get pure Class A, which some magicist think is inherently better than AB1
So I will probably hold off on the experiment for now and just - enjoy the wonderful music that this piece produces.
