2. amps-preamps
  3. 138007-18279

Tube Line Stage Preamp to Drive Class D Amp

I’m super curious about moving around the configuration of my system.

In the winter, I run a Primaluna Dialogue Premium HP integrated. In the summer/fall, I was switching in a solid state integrated--a Creek Evolution 100A. I moved recently and now have a dedicated music room. So the Creek went to the living room and, since it’s still summer--effectively--I needed a SS/cooler amp to run the third floor music room. Enter the NAD M22.

I’m enjoying the NAD M22, and far more so than a Peachtree Nova 300, which I ultimately sold because I felt the Creek Evolution 100A sounded more musical throughout the whole sound spectrum. Right now, the NAD is fed by an NAD M51 DAC. That means my Manley Chinook phono and vinyl collection sit abandoned.

I’m curious to what things would sound like if I moved to a tube line stage preamplifier to feed the NAD M22.

I love the Primaluna integrated and would hate to part with it. But I can’t stop thinking about whether a proper tube preamp might be great with the M22. I could still tube roll on the preamp.

Would this potentially be the best of both worlds? Would it be trick to match up tube preamp output specs to the NAD M22?

Finally, what is it that I like about the NAD v. the Primaluna setup? The NAD is fast and maybe slightly leaner with less glow or ethereal quality. But it has great control and sounds very accurate and there's a clarity into the music that is just as intoxicating as all tubes.

I should probably stay put.  If I do stay put that means no vinyl in the summer in this room because I have nothing to hook the Manley Chinook too.  I can survive, but analog is the drug of choice. 

Curiosity killed the cat though and, if I can confess, I researched tube line stages from Primaluna to Conrad Johnson to Luxman, to Vincent, and on and on.

And then part of me thinks to keep summer and winter systems and just add in a really nice REL subwoofer like a S/3 or S/5 to open up the whole picture.

Forgive me for I love this stuff. 

PS I don’t believe the Primaluna integrated allows me to use it just as a preamp. Too bad...I have a ton of preamp tubs that wI’d love to hear with the NAD M22.

PPS No one seems to talk about it here but the Creek Evolution 100A is Class G--25 watts in pure Class A then the switching kicks in to get you north of 100 watts. It’s a super cool idea and I doubt I’ll sell that little British gem.
128x128jbhiller
jackd
1,068 posts
 
George

Have you actually seen or heard a Freya much less owned one.  If not how do you know what it is capable of other than reading spec sheets.
ghosthouse's avatar
ghosthouse
4,306 posts
 
JB - fwiw I’m using a Schiit Freya pre with a Merrill Audio Class D power amp (Taranis). Very happy with the resulting sound. I use balanced ICs to the Taranis. Early on, I listened mostly to the Freya’s JFET buffer mode. More recently, I got some very nice sounding NOS 6SN7s and now listen in tube mode pretty much 100% of the time. Tubes seems to provide a deeper soundstage and (richer harmonics?) than either "passive" mode.

George is right to caution about impedance matching. I followed a generally recognized rule of thumb that the load impedance of the amp should be at least 10x (some say 20x) the output impedance of the preamp.

With the Freya, output impedances for...
JFET (SE) mode = 75 ohms
JFET (Bal) = 600
Tubes = 210

Comparing these values to the 17000 ohm input impedance that George cites for the NADM22, I think the Freya would be "compatible".

I had been using 78wpc EL34 tube mono blocks and a different tube preamp before the Taranis. I don’t find myself missing tube amplification. I also have a Hegel H200 and a First Watt F7 that I switch off to periodically from the Taranis; so there is some on-going basis for comparison. They all have their virtues. The Taranis gives a good accounting of itself in that company. I am greatly enjoying music from the Taranis driving Totem Forest speakers.

Hope this is of some use.

jbhiller's avatar
jbhiller OP
1,403 posts
 
Thank you!!

George that’s a great idea!  I could spend little, keep both summer and winter systems and still have tubes on the line stage with the muscle of the NAD.  

Ghostbouse, I really appreciate your anecdotal advice. I think this route is a reasonable way to go. And, I need a remote.  Getting up to adjust volume is not ideal. 

Its good old to hear you like this combo with Totem Forests. I’m very familiar with them. It’s also good to hear you aren’t missing the tube power amps. 

I welcome ofger ideas too! 
ghosthouse's avatar
ghosthouse
4,306 posts
 
You are welcome, JB.  I've had the Freya going on 2 years now (p'chsd. Jan '17).  No problems with it at all other than some noisy tubes when first received (Russian NOS) that Schiit promptly replaced.  With well-screened tubes, it is very quiet (even with volume full up and nothing playing).  In JFET & Passive modes, it is dead silent with volume all the way up and ear only inches from the speaker (I don't hold that position too long, however :-).    

If you expect to do a fair amount of tube rolling, get some socket savers (Parts Connexion has some that fit.  Not all will).  These will save the factory sockets and put the bottom of the tubes just about even with the top surface of the chassis.  As supplied, the base of the tube is almost entirely inside the chassis.  Socket savers make changing tubes easier and put more distance between the hot tube and internal electronics.  

If you get one, I hope it works out for you. You'll have 15 days to decide. I would recommend running signal to it 24/7 as it seemed to me to take some time to "open up". You can pull tubes and operate in JFET or passive mode during this time so as not to put hours on the tubes. That is one design aspect I would like to see changed: install a switch or circuitry such that tubes are not energized when using JFET or passive modes.

Good luck whatever you decide.
jbhiller's avatar
jbhiller OP
1,403 posts
 
Ghosthouse, 

I ordered the Schitt to give it a run.  If it's quiet and adds back tube flavor I may keep the Class D in winter operation too.  I'm optimistic that it will sound great as folks seem to love it on forums. The engineering/design is strong.  I really like the volume control and the active/passive function.  If it ran 12au7s I'd be really happy as I have a pile of NOS in that compliment for my Primaluna.   I also like saving a bit of energy and heat. 

I will follow back up with a report after I get it and put it in action!
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