Smack for HD800

[tdogzthmn]

I'm looking at moving over to the Smack as the amp to power my HD800's and wondering if there any upgrades or tweaks that could be done to maximise it's effectiveness with the headphones requirements. I feel that when using the HD800 with the Crack, the true abilities of the headphone are not met.  The HD600 on the other hand is a much more congruent unison.  Could just be my ears and not the amp but either way I want the HD800 to perform its best.

[Jim R.]

With the Smack and HD800s, you just have to set the output impedance to 128 ohms, and balanced if you use a balanced cable and  that's it.

Just curious, what about Crack/HD800s isn't working for you?  IMO thatis a great pairing.  Did you do any upgrades to the Crack, roll tubes, and what's the source?

I was so taken by thee sound of this setup at RMAF along with the BH dac that I just finally broke down and got myself a pair of HD800s (though I believe my wife will also get me a Smack for christmas and I already have a Crack.)

-- Jim

[Doc B.]

For what it's worth Jim was listening to a Crack with Speedball, 91uF Axon caps, a Mullard 12AU7, a 5998 and a higher current operating point. Not really sure how much difference the higher current would make, but the other things do improve the sound over stock. All that said, I happen to prefer the HD800s with Smack set at 128 ohms and running balanced cables. The difference to my ear is a maybe bit more bass oomph and a bit more mellow top end from the Crack and better articulation and a little more natural sound from the Smack. Some might find the HD800s slight tendency to sound bright a little more emphasized with the Smack.

[tdogzthmn]

In response to Jim's post, I am using my Crack with a speedball upgrade and with a 5998 tung-sol, and a valvo E80CC.  My DAC is the HRT Streamer II+ running through BitPerfect.  I believe my set up is similar to your own.  

Dan.  I would say your findings towards the Smack do connect to my feelings towards the HD800 + Crack.  It's the upper treble of the HD800 which sticks up above what I hear with the HD600.  If the Smack is able to rein in more control of the upper frequencies and the lower, I would be very excited.  If the upcoming DAC is able to feed a Balanced Smack from my iMac then I will be very happy to go balanced.

Also is there a way to run the Smack in three channel by creating an active ground?

Thanks.

[Jim R.]

Understood, especially since we all have different listening preferences, ears, etc., but if I were in your position, I think I'd at least try rolling in a different driver tube -- a mullard, rca black plate, tung sol, etc. in place of the e80cc as I recall that tube having a pretty hot top end, especially the german made ones.  For example, I'd avoid telefunkens too... but you probably already know all this and have probably tried it :-).

I actually had no idea that there was a mullard driver tube and film caps in the Crack I listened to, but in some ways that is even more impressive as I generally don't think of mullards as dynamic, transparent and fast as what I heard.

Of course I didn't get to hear the 800s balanced on the smack, in fact I don't recall now if I heard the 800s on the smack at all -- balanced 600s and my IEMs, I think.

BTW, for all you DIY types that like to play with cables, PCX now has their house brand "connex" expanded to include male and chassis mount female hd-800 connectors.  They say the females can be mounted in other headphones as well as chassis, but why one would want a chassis mount one is not really clear to me.  Anyway, they aren't cheap, but less than the Sennheiser OEM parts, and designed for the diy'er and can take larger gauge wire and are easier to work with than the OEM ones.  I'm not recommending them as I've used neither, but the 28-30 gauge wire size limit on the Sennheiser parts, plus their price, is a bit of a deterrent.

Next PCX order I may just get a pair, and a pair of females to install in my 600s as well.

BTW, the balanced S mack only takes a single-ended input -- the balanced output is derived from the center tap of the OPT, so it's not a fully balanced amp that requires a balanced source.  Which is all to say that a usb -> spdif converter on the iMac into the BH dac should make a fine setup -- whether Smack or Crack -- heard them both at the show, sans iMac.  I don't actually know what was feeding the BH dac for the show, but whatever it was, it sounded really, really nice.

[Doc B.]

The 800s were getting passed back and forth among our amps constantly at the show, I wished I had a couple pairs. I don't think anyone heard the 800s balanced except maybe Andy Regan and myself. He came by wanting to hear the Smack, and when he saw the 800s had the stock cable he said "be right back". A couple minutes later we were listening to ironbut's 800s with a Cardas balanced cable from the Smack. Andy had to move on with his cables, so we didn't get to share the sound with anyone. The 800s I recently acquired will be getting balanced cables as soon as I have the wherewithall to do so.

The DAC was being fed via TOSLINK from an early Intel Mac Mini upgraded to a 2.16 GHz CPU and running the current version of Amarra and Snow Leopard. Files are stored on a 2TB USB hard drive and played from memory cache using the Amarra playlist.

I should point out also that because the prototype DAC requires manually switching some DIP switches to change sample rates ( the finished product will automatically sense the sample rate and self adjust) it was almost always playing 16/44 files at the show. I didn't have the time to upload very many high res files, and decided that listeners could get a better feel for the DAC with a broader range of music styles. The real high res was coming from the Nagra anyway.

[Jim R.]

Dan,

Thanks for the additional info -- that makes everything I heard just all that more impressive.  My only question is that I thought the dac was only going to have a bnc, not an optical input, but I suppose, being a prototype, anything goes.  That was all RB?  Hah, just may give my favorite dac a run for it's money as the best dac I've ever heard.

-- Jim

[Doc B.]

Yeah, TOSLINK was the easiest interface for John to get up and running, so that's what the prototype has. There will be SPDIF - probably BNC- and a USB upgrade in the finished version. And yes, I think all the digital anyone heard from us at RMAF was Redbook.

[tdogzthmn]

My plan is to pick up a Balanced cable for the HD800 and run it through the smack.  Which type of balanced connectors come with the Smack, the standard 3 pin? I want to be sure that I have a match to the connectors of the HD800 cable.  I would also like to know if there any opinions as to which tube might sound best with the HD800? I am new to the 5687 type tube and hope to be sure a keep an eye out for some good options to collect. 

[Paul Joppa]

The 7044 and 6900 are the only pin-compatible tubes in the GE manual. The 7044 is thought by many to be very nice. However, many companies have data sheets, and may or may not have made their own versions of the 7044 or 5687. This is the first time we've used this tube, so our in-house experience base is limited.

The 6900 is probably the most drool-worthy, it's a Bendix Red Bank version. Vacuum Tube Valley did an article on the Red Bank tubes:

http://www.vacuumtube.com/issue5.htm

Note they say it has more transconductance than a 5687, but in fact the specs are identical. I have never even seen one of these, and have no idea whether it actually sounds any better than another version - but it's sure as heck built like a tank. Note - just an example - the high temperature glass; you supposedly can boil it in water then drop it into ice water without damage. Heater cathode rating is +/-500 volts due to the ceramic cathode sleeve. Perhaps it should be paired with the Khozmo attenuator!

[Jim R.]

There's also the 7119 and sq and pq variants of that.  If you find any 6900s, let me know -- been looking for a pair of these for years.

BTW, I recently picked up a NOS quad of GE 7044s for a very nice price and intend to use them in my smack.

-- Jim

[Doc B.]

I'm using 7119 PQs.

[Paul Joppa]

Oops - I forgot the 7119/E182CC, it's not in the 1973 GE handbook. It has more gain, and twice the rated lifetime of the 6900...

[Jim R.]

Oh boy, back to tube school for you :-).

-- Jim

[tdogzthmn]

Any word on how these options might play off the sonics of the HD800 favorably?