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After listening to a Schiit Freya S preamp for six months I'd come to the conclusion that I prefer the passive setting (paired with an iFi iTube2 buffer), which surprised me since I assumed the active mode of the preamp would provide the best sound based on the comments and reviews I'd read. And at first I did prefer the active gain mode, with or without the tube buffer. But I eventually settled on the passive mode using the buffer, it just had the right mix of resolution and richness. Last night, though, I was (re)reading about passive vs active preamps and started questioning my decision, especially since many of the articles and forum discussions mentioned the problems inherent with using a passive setup.So I went back to square one and experimented with six permutations between preamp and buffer to see if I still thought using the preamp in passive mode with the tube buffer was still my preference. The Freya S has three modes: passive, active 1dB gain, and active 12dB gain. The iFi iTube2 has three tube buffer modes: SET, push-pull, and one they describe as "a sound parallel to classic, low-distortion tube-based studio equipment". All three tube modes impart a fairly mild effect, especially the "classic" mode, and I found that after months of trial and error I prefer the SET mode with my stereo system, regardless of passive or active preamp modes. That's why I limited my experiment to the SET mode of the iTube2.
What I discovered is that I prefer using the tube buffer and the effect is noticeably different between passive mode and active modes of the preamp. The main difference is how much more of the "tube bloom" effect I hear in passive mode, without losing the resolution and dynamics of the active modes. It surprised me because I had a pre-decisional bias that the active mode(s) must be better and that my decision to use the passive mode was an overeager desire to adhere to the "straight wire" paradigm. Turns out it was more than that; the combination of passive preamp and tube buffer sounds much more relaxed, with the correct timing and dynamics of music I hear when attending music performances and concerts. The music just came alive and sounded more (using an overused term) "natural". The difference was not subtle and sounded so good that I ended up listening to music way past my bed time.
All I can figure is that with my setup (sources, pre-amp, amp, speakers) the passive mode in the Freya S and the buffering effect of the iTube2 provides a good matching of impedances throughout the signal chain. Either that or I'm rationalizing again. :-)
Tom
Edits: 10/02/21Follow Ups:
is somewhat like all these tube buffers and switching one supposed tube stereotype for another.
There is a sports car engine - and then there are cars that pipe in a sports car engine sound through your car speakers. Get the V8 GT Mustang if you want the real engine sound - not the 4 banger with the pretend V8 sound. V8s sound different too - just like SET amps sound different from other SET amps. Ditto Push-Pull tubes. So having a setting that says SET is kind of a warning. Like, surround receivers that have Hall, Church, Club, Concert, etc. Gimmicks.
Your point is well taken in that I have heard many tubed preamplifiers and a few tubed amplifiers in other systems and the iTube2 ain't one of them. In that respect the "SET" and "push-pull" settings are just labels. But for some reason the buffer stage setting called "SET" when used with my SS pre-amp in passive mode sounds pretty good. They could have just as well called it "Gimmick #3" and I'd still prefer it.
Tom
sorry, couldn't resist :)
If art interprets our dreams, the computer executes them in the guise of programs!
(versus pure passive mode) is primarily a mild-moderate increase in both fullness and dynamics, and a slight decrease in already-excellent transparency.
Mark in NC
"The thought that life could be better is woven indelibly into our hearts and our brains" -Paul Simon
Good to know. That's basically what I hear as well but my perception of delicate transparency is diminished. I do hear upper-middle frequency harmonics and can hear slight changes in transparency (as generally used) at those frequencies. But slight changes in high frequencies is not something I can pick out consistently. The bloom in sound is something I can distinguish with regularity.Tom
Edits: 02/22/21
time will pass, you'll get something new or try a different tube and then you might change again..... There are many different possibilities with the flavors and I would venture to say we've all been there before with a lot of the equipment we've tried over the years. People blow loads on cables for something 'better' like it was a sexual experience.
Even Doctors with years of experience and study have errors in judgment.
Guilty as charged. For exactly what, I'm not quite sure. :-)Tom
Edits: 02/21/21
'People blow loads on cables for something 'better' like it was a sexual experience'
wow ... talk about Freudian!
'Even Doctors with years of experience and study have errors in judgment'
did you realize that you've just proposed audiophile malpractice insurance?
say, you don't sell insurance do you?
regards,
Over the years we've all seen some here claim an eruption over a certain cable improvement. Good gosh. I've changed something before only to find out later when I go back, that it was not such a big deal after all because what I heard as an improvement was merely the break-in of the new.
It wasn't a proposition, just an observation. My bro is a doc and he tells me stories of what goes on there. There are good ones and bad. He told me to always get 3 consults if you get a bad prognosis. It happened to me once and it turned out fortunate.
I would think no one would buy audiophile insurance. Maybe the extended warranty at a place like Magnolia.
just making a little light of your comment Story
y'know, shooting for humorous effect? ah well ...
it's not the first or last time that falls flat
the AA can be a 'tough room' but do tip your waitress
best regards,
I do not have a Schitt Freya, but I have had a lot of active preamps. I am now using a buffer preamp which includes two solid state buffers and a tube buffer. I kind of agree with the other responses in the sense that (you can switch between them on the fly), the tube buffer does not create a "tube" sound. The soundstages are different, and the sound (forward vs behind the speakers) is different, and some bass impact is different, but when I go from SS to tube, no one has ever said "ahh, that must be the tube circuit" or "aha, we went from tube to ss". It is a very interesting experiment.
I like the buffer better than most active preamps I have owned.
I linked to a post about my preamp below.
The sound with the passive Freya S and iTube2 doesn't have the bloom that the tube preamp I used for a few years had, that's for sure. But I do like the sound and the dependability of the SS preamp/buffer combination. I guess I'll have to keep looking for a true(?) tube buffer stage.Tom
Edits: 02/22/21
I hope you understand that the iFi iTube2 buffer is just an Opamp based device with one 5670 tube thrown in so they can call it a "tube" buffer. The "modes" you speak of are just emulated, not physically realized.
The device operates from 15vdc.
A 5670 tube can not be operated in a linear, low distortion fashion at such a low voltage. Triode tubes, when operated properly, exhibit very little upper ordered harmonic distortion and that is why I use them. But to do so the 5670 would have to be operated with something like 150vdc on the plate and about 8ma of plate current flowing at idle. An operating point that is not achievable in the iFi iTube2 buffer.
but if it sounds good to you I guess that's all the matters.
My advice, if you want to hear what real tube circuits sound like, get some real tube gear.
Sorry for the rant. Don't take it personally. It's just that solid state gear with a tube thrown in so they can market it as a "tube unit" is one of my pet peeves.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
I knew there were SS components in the circuitry but I'm curious, though, about the 1M Ohm input impedance in buffer mode, that and the low 150 Ohm output impedance. I thought such high input resistances were the hallmark of tube circuitry while a low output impedance was the benefit of a solid state output stage. I've noticed that many of the tube buffer stages available use a tube input stage and solid state output stage, taking advantage of those attributes.I have a tube preamp and used it for a few years and really enjoyed the sound. But it was
blowing throughburning up rectifier tubes faster then they should have and I got tired of not knowing if was going to fail on me at any time and having to replace $40 tubes. Thus the purchase of a SS preamp and tube buffer stage.Oh, well, I'll just keep listening to it and meanwhile figure out if I want to pursue a true(?) tubed buffer stage.
Tbanks for the information.
Tom
Edits: 02/22/21 02/22/21
Which model pre-amp was blowing through rectifier tubes? --- I have been using Tube Amps for over 25 years and have never gone through more than 1 or 2 rectifier tubes.
I should probably go back and edit my last post. It's probably a bit of hyperbole but it did go through two right-channel rectifier tubes in a matter of 3300 hours. The first tube went after less than 3000 hours and the second tube went shortly after. I put two new tubes ($80) in the first time and replaced the fried 300 hour tube with the good 3000 hour tube. After a couple hundred hours it's still working but I don't trust either of those tubes nor the right channel of the pre-amp. I'm soured on tube gear right now. But 0dB gain tube buffer stages don't seem like they're getting stressed very much since they're running at relatively low voltages. Just a bit of tube gain is actually a good thing. Or at least that's been my experience.I'd rather not say which model of pre-amp I'm talking about. I'm just going to let it slide and probably give somebody a great deal on a tubed pre-amp with a suspect right channel.
Edits: 02/22/21 02/22/21
with a Bellari VPI129 phono stage. It had a single dual triode protruding prominently from the top of the case, but all the heavy lifting was done by four op amps.
.
Have Fun and Enjoy the Music
"Still Working the Problem"
I believe using a tube as a buffer adds no "tube" sonics to the sound. It simply changing the impedance.
"I believe using a tube as a buffer adds no "tube" sonics to the sound. It simply changing the impedance."
That's what one might hope for, but the fact is that many of the cheap "buffers" intentionally add H2 distortion to give a phony tube "bloom" that does not exist in carefully engineered tube electronics. Further, even a buffer without added H2 distortion will still add noise and distortion to the signal as it passes through the buffer.
In fact the entire buffer craze is ridiculous: there is NO impedance mismatch between a CD player/DAC and any modern amplifier either preamp of power amp! It is a notion promulgated by vendors who prey on non technical audio enthusiasts.
I can understand the added distortion coming from the solid state stage. And that it could mimic the beneficial (if it's something you like) distortion of tubes. Clever tricks perhaps. But I hear something very similar to what I hear with two different tubed pre-amps. They must have figured out how to realistically mimic the sound of tubes. And I'm not sure I agree with your assertion that a tube used to change impedance does not (or can not?) also impart tube euphonics in a buffer stage.As for the buffer craze, I don't know if there is or not, I don't keep track of those things. I have been using a tubed buffer stage since 2006, not always in the system depending on what I'm using at the time. I originally bought it to tame the harshness of a legacy CD player and early CD releases that made my ears hurt listening to them. I took it out of the chain when I bought a nice sounding transport and DAC. I put it back into the chain when I upgraded to a tubed preamp in 2017 because their WAS an impedance problem between the somewhat high output impedance of the preamp and the somewhat low input impedance of the power amp, plus, it was driving low input impedance plate amps on two subwoofers. The bass sounded heavy and thick, the upper frequencies all but disappeared, even for me, and the overall sound was overly syrupy. I remembered that I had the tubed buffer stage so I put that between the preamp and subwoofers and put a Loki Mini tone control (which acted as a buffer) between the preamp and power amp. What a difference; things made sense once again. I really enjoyed the sound of that tube preamp.
I had a similar (though less dramatic) experience with the current solid state passive pre-amp setup. I just found that the iTube2 put some of the bloom back into the mix. It just sounds better. Is that improved impedance matching? Clever solid state distortion tricks? Or just a bit of tube harmonics? I don't know for sure but I prefer it, whatever is causing it.
Tom
Edits: 02/28/21
"I'm not sure I agree with your assertion that a tube used to change impedance does not (or can not?) also impart tube euphonics in a buffer stage."
To be clear: I never intended to imply that nor was that my point. I said that some, particularly inexpensive Chinese buffers, intentionally bias the tubes so as to generate 2nd harmonic distortion instead of biasing them in their most linear region. A well engineered tube stage will generate H2 and H3 distortion well below the signal voltage so that it can be <1% at full output.
A quick example is the Western Electric table of operating points for the 300B. The H2 distortion, according to operating point, ranges from -18dB to -31dB below the signal. This is obviously a huge range of difference in distortion possible for this one tube.
My point again: some manufacturers intentionally create H2 distortion in their buffer product to give it a tubey bloom or euphonic sound and in reality that is its only application. To me, this is not hifi but noise generation.
So if the iFi iTube2 is doing exactly what it was designed to do, that is, provide a good buffer stage (1M Ohm input impedance/150 Ohm output impedance) while also offering a bit of tube euphonics, why did you infer from your original reply that this was just another "cheap" tube buffer taking advantage of a "ridiculous buffer craze"?
Otherwise, you seem to be struggling as to what you are trying to say about my original post. From what you've posted so far I get the impression that you don't like buffer stages, and you especially don't like buffer stages that promote tube euphonics. And I'm not quite sure why you used the 300B power tube as an example as to why you think tube buffers are bunk.
Look, I obviously don't have the understanding of tube technology that you seem to have so if you can add something constructive, I'm all ears.
Tom
I made no comment directed at the iFi iTube2. If this is a cheap Chinese buffer you have been apprised of my opinion.
'it was driving low input impedance plate amps on two subwoofers'
this caught my attention ... how were they connected, or driven?
regards,
I may have phrased it wrong. I run active stereo subwoofers, one sub for the right channel and one sub for the left. Each subwoofer has a class D plate amp. I couldn't find a data sheet for this particular sub but from everything I could find regarding the typical plate amp used on this type of subwoofer I assumed they were relatively low impedance amps, plus they were being run simultaneously from the second set of RCA outputs of the pre-amp.
Apparently the subwoofer plate amp(s) and power amp combination were causing problems for the pre-amp. Inserting a couple of buffers seemed to solve the problem. Quite well actually. But it may be specific to my particular stereo setup. It might not be, though; I got the idea from reading about similar impedance mismatches.
Tom
'from the second set of RCA outputs of the pre-amp'
would you expand on this please? what are they labelled / used for?
if there's always signal available there I'm surprised it would imbalance the output impedance; not saying you're wrong just trying to understand it
regards,
From my limited understanding the pre-amp "sees" the current loads on each set of outputs as cumulative loads, not independent, isolated loads. If there's too much of an imbalance (ratio of output:input less than 1:10) in the resulting impedance the pre-amp may not be able to efficiently drive the signal to either set of outputs and you can end up with considerable distortion at both ends of the frequency spectrum, especially the bass.
I'm fairly certain that's what was happening to my setup. I may have the technological aspects wrong but putting the buffers into play solved the problem.
10-4 ... one last question: this is the Freya, yes?
I appreciate your indulgence, you've put together a nice set-up
regards,
The problems were with a tube pre-amp I was using. The Freya S didn't have the same distortion problems (at least not that I noticed), it was more that adding the iFi iTube2 buffer added a nice touch of bloom to the sound. What I discovered is that the buffer may be also helping out with impedance matching, which might explain the noticeable improvement in sound while using it, especially in passive mode.
thank you sir
the Shiit line is very appealing to me, too bad it's not in black
black is beautiful for components on my shelves
or maybe I don't mind dusting or something
who knows?
regards,
I had a black VW Jetta GLI with nice alloy wheels that looked fantastic. When it wasn't covered in dust. ;-)
You might be wrong. :-)
I have an Eastern Electric MiniMax BBA tube buffer and it definitely adds tube euphonics. Like the iFi iTube2, the amount of gain is dependent on a solid state gain stage. And I have a Jolida JD9 phono preamp that definitely changes character with a change in tubes. The gain is primarily from opamps so the tubes are acting more as a buffer.
I could be wrong.
Tom
The tube in the iFi iTube2 buffer is not wired as a cathode follower buffer. The unit's output stage has to be an Opamp. The stated output impedance is <100 ohms.
Also, when you run a tube at such low voltages the tube will not be linear and it will add distortion and that will affect the sound.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Aren't your descriptions of the iTube2 what a tube buffer stage is all about? I guess it depends on how much (and what type of) distortion is added as to whether the buffer is beneficial. In my situation there is a benefit to the overall impedance of the system in that the sound improves when using the buffer stage.
Paired with the VTV Purifi amp, Passive left the sound cool and analytic albeit with unbeatable resolution, transparency, and dynamics.
Of course the Freya + has its own, switchable Tube gain stage. unfortunately this added a moderate tube effects but left me with a discernable loss of transparency, so I was using mostly the Passive mode.
Adding a tube buffer external to the Freya is an interesting alternative I hadn't considered but I can see it might work. I had have a Glassware Aikido preamp core that I might have used downstream of the Freya +, but I didn't try it because I had already determined that the Aikido involved 'way too much loss of transparency and dynamics.
Thanks to a fortunate opportunity I ended up with a Sonic Frontiers Line 1 tube preamp, selling on the Freya +. The Line 1 delivers mild tube effects with little or not loss of transparency, etc.
Dmitri Shostakovich
It sounds good but apparently I've been had based on some of the comments on this thread. Oh, well, apparently I got taken when I bought a Jolida JD9 phono stage (which I still own and use) so it's not the first time. '-)I'll probably keep the Freya S but will look for a "true" (tongue-in-cheek air quotes) tube buffer stage. I still think it's worth looking into since I plan on continue using the Freya S in passive mode.
Tom
Edits: 02/28/21
I own two Musical Fidelity X10 v3 tube buffers. Currently they are not in the system but often one is.
I have never opened them up but they are 20+ years old. I don't know but I think it is much less likely they use op amps in the signal path.
If art interprets our dreams, the computer executes them in the guise of programs!
I use a X10 v3 with my DVD player. Here's a photo of the guts of the X10 v3:
I much prefer the iTube2, at least in my system.
Edits: 02/28/21
Thanks! Looks to me all discrete components?
If art interprets our dreams, the computer executes them in the guise of programs!
... Though it's probably of limited appeal.
I mentioned I built a Glassware preamp, their Aikido 12VAC model, but never completed it with volume control, input selector, and proper case. I did use it with Jolida passive preamp, but didn't happen to care for it much. Still, the concept was valid. Picture ...
Glassware also produces buffer-only kits.
Dmitri Shostakovich
I really don't want any more gain in the signal path. The Freya S's passive mode and NAD M22 power amp gain (29 dB) is just about perfect.
I've had my eyes on a Tortuga buffer stage for years. It's not inexpensive but then again I only paid $600 for the Freya S so combined cost would be $2100. Not bad for a very flexible preamp stage.
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