Schiit Buf: tube buffer + gain

[oldsysop]

Soundstage opened up nicely (wider, more fleshed out), phantom center strong and clear, added a warm/vintage/touch of liquidity...

 

[Jacque]

That’s what early users reported; I haven’t tested myself to verify. On the tube side, there’s a JJ E88CC 6922 tube I may get, it’d be right about $30 shipped. Anyone have experience with that one?

I have a JJ 6922 gold pin in my Buf right now. In my setup the bass really seems to be emphasized with it. Too much so when I use my teaks. Treble seems to be rolled off some. I don’t like it with the teaks, but it works great with my r50x. It’s a bright headphone, really bright to my ears. The taming of the treble helps with that particular pair of headphones and the emphasized bass is nice with it too. To be honest though I prefer the stock tube over the JJ overall. My JJ has around 70 hours on it at this point. The sound it adds noticeably changed somewhere around the 50 hour mark. I’ve been watching several eBay auctions that have the ‘75 Voskhad 6n23p grey shield getter on a wire tubes but I’m having a hard time pulling the trigger on any of them at this point. They’re pretty much all being sold from Ukraine and I worry that won’t receive it plus if I do shipping time is listed at around 4 to 6 weeks. Many think it’s a really sweet tube though.

 

[Cbdb2]

It will get you part of the "tube sound". Tube power amps also have output transformer distortion and some even have sagging rails to add more distortion at higher levels. (distortion vs level measurements would be nice to see)
If your going to build an effects box why not make the distortion variable with a drive dial like guitar tube amps?

 

[xllr8]

@oldsysop

 

[Joe Smith]

I probably need to connect the Buf to my headphone amp and do a little A/B listening to see what I can hear before I order a different tube... Probably a wise first step...

 

[john61ct]

Yes in fact I reckon at least a few dozen hours.

Note that unlike SS gear, tubes really do need time to warm up (literally!)

and they also routinely need replacing as they wear out.

 

[xllr8]

Yes in fact I reckon at least a few dozen hours.

Note that unlike SS gear, tubes really do need time to warm up (literally!)

and they also routinely need replacing as they wear out.

what are common lifespans? 6DJ8s?

 

[Bob from Florida]

what are common lifespans? 6DJ8s?

10,000 hours is possible for preamp tubes. The 6N1P supplied is a very quiet, rugged tube that may last longer. It is not exactly a 6DJ8 or 6922 and while you can drop those in the socket and they will work, they won't necessarily match well with the circuit. A lot of 6DJ8/6922's are microphonic in higher gain circuits while the 6N1P is almost never microphonic. You might hear that in the "gain" position with this product.

 

[xllr8]

10,000 hours is possible for preamp tubes. The 6N1P supplied is a very quiet, rugged tube that may last longer. It is not exactly a 6DJ8 or 6922 and while you can drop those in the socket and they will work, they won't necessarily match well with the circuit. A lot of 6DJ8/6922's are microphonic in higher gain circuits while the 6N1P is almost never microphonic. You might hear that in the "gain" position with this product.

I don't "need" the gain, but it i think it adds a diff sound (beyond volume of course). I did choose the "low noise/microphonics" & "balanced triodes" upon checkout from tubedepot.

I guess I'll find out soon enough. Am hoping to capture some of that "..very lush presentation with a 3 dimensional soundstage."

 

[Bob from Florida]

I don't "need" the gain, but it i think it adds a diff sound (beyond volume of course). I did choose the "low noise/microphonics" & "balanced triodes" upon checkout from tubedepot.

I guess I'll find out soon enough. Am hoping to capture some of that "..very lush presentation with a 3 dimensional soundstage."

What the below means is a 6DJ8 can be used in a 6N1P design but not vice versa because of the greater heater current of the 6N1P. However, because of the difference in transconductance, the operating point at quiescent bias will be different. Resulting in harmonic distortion without circuit modifications. If the goal is to introduce distortion to change the sound, you may succeed with the tube swap.

 

[LumiAudioNut]

I purchased a Schiit Buf to add to my, otherwise almost perfectly measuring signal path (SMSL SU-10 DAC ---> Schiit Kara S in passive mode--->Purifi amplifier), so that I could enjoy a cheap easily removable source of pleasant (to me) harmonic distortion.

It works as advertised, but please be aware you'll get quite audible pop if you turn off the Buf before turning off the amplier/s first (you'll only make that mistake once!).

My speakers are only 86db efficient, so I can only imagine what the thunking sound would be like over a pair of highly efficient speakers (Klipsch, Zu audio, etc)

-Lumi

 

[Joe Smith]

Also don’t change the gain setting during active use, same result. Switch off your amp before doing anything “in the buf.”

 

[Jim Creek]

The Buf seems like a fun device to play with but I have a technical question. I would be using a Topping Pre90 with an RCA output to the RCA input of the Buf. Then I would have to use an RCA to XLR cable to connect to the RCA output from the Buf to the XLR input to my Purifi Eigentakt amp. Are there any issues with this connection chain?

 

[john61ct]

Well of course you COULD screw up the SE to balanced adapter

but that is much more straightforward than the other way around.

With plain wiring adapters you lose gain, and ofc the common-mode noise rejection of a true balanced circuit.

Is it possible to create a balanced RCA to XLR cable?

And if so, is there anything "less" balanced about such a cable than a mini-XLR to XLR cable? I'm asking in the context of Pro-Ject turntables, as I decide between two different models, one with and one without a mini-XLR output. Finally, if such a cable is possible, is there anything I...

www.audiosciencereview.com

Something like Art Cleanbox Pro or Aphex 124b is "the" most foolproof way.

In the main Schiit thread some are buying 2x Buf units to "go balanced"

more complex wiring I think, seems nuts to me

 

[mhardy6647]

more complex wiring I think, seems nuts to me

Indeed -- the very definition of scope creep.

 

[ashmaxim]

The Buf seems like a fun device to play with but I have a technical question. I would be using a Topping Pre90 with an RCA output to the RCA input of the Buf. Then I would have to use an RCA to XLR cable to connect to the RCA output from the Buf to the XLR input to my Purifi Eigentakt amp. Are there any issues with this connection chain?

Love to see this discussion—this is my first post. I couldn’t resist registering and replying immediately once I saw like-minded people with the same equipment.

First of all, to all CNAMPX users here: I have a CNAMPX without the CNXBRMO, like many of you. I’d like to share that I’ve rewired it for a direct connection without any bypass switch, so now it’s fully plug-and-play.

Secondly, I wanted to bridge it (i.e., mono summing, similar to the CNXBRMO). I have a Topping PRE 90, but the issue is that one XLR needs to be phase-inverted for mono summing.
So I bought an RCA-to-XLR cable and a phase reverser. Done and dusted—I’m getting 200 W per channel.

When you do mono summing, the only issue is that the damping factor is cut in half.

Enjoy! That said, I still doubt whether converting from unbalanced to balanced is a good idea. If you’re looking for a good buffer, go for ModWright.

 

[john61ct]

WOW this is exciting!

Some in that thread are getting two Bufs, just so it can be used with XLR, using specifically wired Wye adapter cables to shift phase then re-combine.

I want to emulate Crestron's CNXBRMO bridging interface for their CNAMPX-16X60 16-ch amp (bargain!) and it seems to be the same idea

Any chance you could somehow diagram this at ELI5 level ?

I don't DIY myself, but my son has soldering friends I may be able to bribe to build these for me...