Schiit Saga vs Freya

[4est]

It's called a dual triode.

I wonder what the differences in circuit really mean. The Saga has a single tube buffer - how that even work in 2 channel stereo circuit escapes me....

[4est]

I certainly agree that matched pairs are indeed intended to be as close to each other electrically than anything else. However, I'm of the camp that believes that the electrical differences are the audible ones when it comes to anything other than speakers. While you can match potential plate currents in matched pairs as their resistance would be similar, you can also match their potential for gain (capacitance?). Thus, get them electrically close and you would be audibly matched. Again, just my opinion, as psychoacoustics are largely at play in this industry.

 

To me, this explains why tubes from the same manufacturer (especially if you buy direct, and not from someone like TAD, Ruby, etc.) will vary slightly in sound, and thus, electrical values, even within the same batch of the same model. The rest, well, I don't hear anything beyond 12kHz at my age probably, so it doesn't matter.

 

If a NOS tube has a different number/letter post script, there is likely a difference- mica thickness, grid spacing or wire diameter, cathode composition, plate structuring ect. Back then tubes were responsible for mission critical duties, and were taken very seriously by the manufactures. There was fierce competition and a of of ad copy extolling their virtues vs the competition. Put another way, in the era where tubes ruled and were made better, they thought there were differences.

 

As to matching small signal tubes, it depends upon their use. Those 6sn7 variants are dual triodes, and the gain ©should be matched on the halves if used as a gain stage. For a buffer, it is of little concern. None of that is taking into account the variation in noise, and one of the more common issues, microphonics.

 

I could go on and on about this, but the simple fact is that NOS tubes are sought after because they sound better due to workmanship, chemistry and the rigorous selection processes they used back then and not today. Most modern tubes are junk- period.

[4est]

''Most modern tubes are junk- period''.

 

 

 

Hey that seems a little harshJ

I’ve been running RCA in my SAGA for a few weeks now but the Tung Sol popped through the letter box this morning and curiosity got the better of me.

A bit of a nice surprise really.

After a few hours cooking.

Firstly I’d say that to my ears and in my set up these sound quite a bit better than the stock tubes and in comparison to the RCA are richer and rounder. They also have a slightly different sound shape compared to the wide and high RCA they are just a tad slimmer and less tall. But they do seem to have a deeper presentation with more of the tube mid’s which puts more meat on the bone of vocals for example. Nicely deep in the bass also. The top seems to have just a little less sparkle than the RCA but that may change as these tube really warm up.

Big, beefy, and very fruity so far without losing detail.

Not bad for a current production tube and the Russians can make them BTW. I’ve had some very nice 6n1p/6n6p in the past.

I’m liking the Tung Sol ATM.

It’s great fun.

 

 

Yes, you are right, it was a bit harsh. My bad, but it is largely true. It is also early days on those tubes. Reliability and longevity are two of the areas where old tubes excelled over the modern variations. To my knowledge, some of the old metallurgy and chemistry was lost, and the modern ones just don't have the same magic.

[4est]

Well, I can assure you that the base of the Psvane CV181-T mkII is firmly attached to the valve.

 

Regardless, one should never pull a tube out by its glass. You should grab it by the base. The Schiit may make that difficult, but one should still try. I've seen NOS tubes separate as well. Especially an output tube such as the aforementioned 807, which is a nice tube btw! I listened to some old Altec theater amps that had them.

[4est]

My experiences (and thus, my opinion) tell me that Chinese tubes are particularly junk. It's not that they sound bad, but their build quality ranges from mediocre to unbelievably bad. For instance, how about tubes with phenolic-bases (such as octal and 5-pin (2 fat pins, 3 skinny ones) that have the glass envelopes literally come out of their phenolic bases (and break wires) when one tries to remove the tube from it's socket! Or, with tubes have a plate cap, having the tube cap come off when one tries to remove the plate lead. The cap comes off stuck inside the plate lead connector so that it has to be dug out with a knife blade, leaving only a short stub of useless wire sticking through the glass on top of the tube! I've seen the bases separate on Chinese octal-based tubes such as 6SN7s, and both the bases and plate caps come off on 807s (an 30 MHz spec'd 6L6 used throughout the 2nd WW, and up into the 1950's for military transmitters and more recently used as an audio output tube).

 

 

[ATTACH=CONFIG]33033[/ATTACH]

 

You are correct, the Chinese tubes are primary culprit, but many of the Russian tubes still do not have "it".

[4est]

Chinese Psvane "replicas" I own are very well constructed and sounding very good, very reliable (some of them bought 4 years ago).

 

101D Replica, 300B Replica, EL34 Replica, between others. And they cost high money, of course.

 

"Everything China" is bad quality? Very wrong, but if you want the best quality you have to pay.

 

I have a relative who imports from China a lot of things, he told me you can choose from 5 quality levels.

 

Of course I also have some NOS tubes in stock, where the honest sellers are very few, they are a lot of fake or in very bad condition. You have to be very cautious on eBay...!

 

Regarding tube manipulation, you have to treat them like a lady, but they are not as weak as some believe (the same with the ladies)

 

Roch

 

This makes complete sense to me. Much of what Americans bitch about in Far East goods is only because Americans so often buy on price, and the our local suppliers only order the cheap shit. Even so, I doubt anyone is making tubes today as well as they did when the world relied on them.

[4est]

I have no experience with a Tube preamp. Do preamp tubes need bias adjustments like a tube power amp?

 

Generally, no.

[4est]

Are you sure? I'm just asking, because "tube-driven" would indicate, to me, that the tube is an active gain stage, as opposed to a cathode-follower buffer stage. It would make a difference.

 

I agree that it would make a difference, but I do not see how "tube driven" would imply a gain stage over a buffer.

[4est]

Thanks - if anyone else has any insight as to this question I would be interested...

 

What is the actual question? 6550= 35 watt plate dissipation vs kt120= 60 watts; 6550 good for 60-75watts

Another overly simple way to view it: higher plate voltage= larger V swing= more watts= more heat =shorter life

 

As with an engine, you can always adjust to get more power out of it right up until it breaks or wears out. A tube is a voltage controlled current valve. Higher voltages allow for higher currents through the plate resistance which gives more power at the expense of tube life.

[4est]

Thanks 4est - this is a good explanation and what I thought was the reality of the situation. I just wondered if I was missing some aspect that allowed Rogue to run their KT120's at 100 watt a push-pull pair vs. 60-75 a push-pull pair (as almost everyone else does) and avoid the "higher plate voltage= larger V swing= more watts= more heat =shorter life" consequence. One thing you read about from end users is the claim that Rogue's gear has "long tube life" and the like. But how, given the fact that they are running their KT120's "hotter" than everyone else?

 

I was attempting to keep it simple by not mentioning bias current-bias being the amount of current flowing at idle. FWIW, I do not think 100w is a lot for four 6550 or KT88/90/120. As I mentioned in my earlier response. The 6550(these are all 6550 variants IMO) is good for 60, maybe 75 watts per pair. It does not seem as if they are running them hard.

[4est]

Well, according the manuel online at Rogue's site:

 

"Using the bias tool, slowly turn the screw on the potentiometer that is adjacent to theswitch until the bias meter reads ~ 35 miliamps (mA)."

 

Is 35 mA a 'hot' idle current setting for the 6550?

 

update: I am not trying to denigrate Rogue here - in fact I like the sound I have heard from this amp when I have demo'd it in the past and could easily see myself owning one despite the fact that I might be investing in tubes more often - I just am trying to get a grasp on what the design is really doing...

 

Not at all. The vintage HK Citation II I am running was 100ma stock, but I have reduced it to 85.

 

I just realized this is off topic- my apologies.