[Kouzelna]

Hi all,
 
After many headphone tests over the past two years, as most of you know I settled on the K702.  It's the best of all worlds for me, seeing as I don't have the cash for a T1 which I think would be the next (final?) step up in Headphone Gloryland.
 
Anyway, the best amp I've heard these on so far with this amp is the Glow Audio One, which I loved.  Unfortunately, I sold it, so as to facilitate my moving overseas this summer.  
 
I got by for a little while with my little and much loved BSG solid state, but I really missed the tube sound.  So, recently I settled in with a Millet Starving Student which is nice, but, not all there.  While I like it, (it's an improvement in some ways over the BSG for these cans specifically), when I listen I still hear something is missing.  And it just doesn't bring the K702 to their fullest potential.
 
So here's the deal:
 
I'm hoping you can help me find the best tube amp for these particular cans, on a relatively slim budget.  
 
Ideally, I'd like to go with a Woo 6+.  But I really can't swing the dough right now.  So...?  I turn it over to you guys to help me out.
 
Amps I've used in the past besides what I've mentioned include the Grace 901, which I liked but it was simply too analytical.  Plus it's not a tube, and I really love the tube sound.  And the Millet HA-1, which was the best amp I've ever heard.
 
Based on that, and about a $300 budget maxed (I'm happy to buy used, and cosmetically challenged...), what can you suggest for me?  Portability is a help, but not a deal killer.
 
Many thanks to all of!  I love this site, it rocks!!!
 
(P.S. I'm willing to sell/trade my Starving Student to facilitate buying my new amp).

 

[smial1966]

Hi,
 
I don't know whether it's too near to the initial release date for used models to appear for sale yet, but I reckon that a second hand ALO Continental MK1 would be a good match for your requirements. Failing the Continental, I've heard it said that the TTVJ Slim sounds tube like in certain sonic aspects and there are definitely used models of this amp about.
 
Cheers.
 
P.S. There is an interesting review of the TTVJ Slim over on Headfonia.  

 

[Uncle Erik]

You need an amp that has an output impedance lower than 62 Ohms, which is the impedance of a K-702.  An OTL won't have an output impedance low enough (read up on the damping factor if you're not familiar with it) save for the Zana Deux, which is outside your budget.  Its 6C33C tubes have a low output impedance, and it is the only OTL of its kind available outside of DIY projects.
 
Otherwise, you need a transformer-coupled amp.  Output transformers are not cheap.  The least expensive transformer-coupled amp is the Bottlehead Smack at $500 and you have to assemble it.  I've paid $500 for a pair of Sowter output transformers, not including the rest of the amp.
 
However, you can find a good solid state amp for $300.  Solid state has a low output impedance and you don't have to spend a lot of money on a high voltage power supply or output transformers to get it.  And solid state sounds good, too.  The end goal is to make your headphones sound good.

 

[Jojomite]

something from little dot? no personal experience though><

 

[atothex]

I'm with Erik. Why go tubes? To "warm up" the K702s?
 
That's really the wrong approach, imo. You want amps to match the phones, not work against them. Getting a cheap OTL amp will simply drop out the bottom end and make the entire system sound lifeless and weird.

 

[liamstrain]

The new Beezar Torpedo will work too, if you are down with DIY, and should be less than the Bottlehead Smack. 
 
But really - the best inexpensive amp for the 702 is the Matrix M-Stage. They warm up very nicely. 
 
 
I will say - however - despite the conventional wisdom regarding the damping factor - the little HIfiman EF2A tube amp/dac and my 702s play nicely together. Not as good as the m-stage or one of the big transformer coupled amps - but very nice indeed. (*note - I also run a parametric eq with the 702s, this helps correct the bottom end performance and clean up a peak in the treble)

 

[Kouzelna]

I really appreciate all the feedback so far, it's very helpful to me.  Here's my thoughts so far:
 
1.  I'll definitely check out the three specific amps recommended so far by everyone, and appreciate the help!
 
2.  I don't understand damping and output factors - that's what I rely on you smart guys for, Uncle Erik!  And I'm really glad (honored?) you weighed in.  One question: can a simple impedance cable help with that?  When I had my Glow, it hummed mighty fierce with my K702.  But when I added a DIY 235 Ohm impedance cable Armaegis had made for me, the hum stopped, and the cans sounded quite a bit better too.  Will this help with a tube amp that's not built for the K702, instead of the more expensive options recommended?
 
3.  I am fully on board with working with the cans, rather than monkeying around to make the wrong cans work with the wrong amp.  My problem though, is at least so far, I've never really found a solid state amp I've liked the sound of.  Not, at least, when compared with any tube amp I've ever heard.  They just sound different to my ears.  Not as accurate, but, warmer.  They definitely sound different to me, and I like that different quality.  Kind of like LPs vs CDs.  To me, CDs are far more accurate, but their sound is definitely colder compared to an LP played on the same system, which sounds more "musical" I guess.
 
The solid states I've used in the past with many headphones are:
 
Grace 901 (my best)
Newer high-end Yamaha integrated
70s high-end Toshiba integrated
Adcom GFA-555
Headroom Airhead
NuForce Icon Mobile
BSG (which I love for my ER-4)
 
 

 

[Mellonhead3013]

The Graham Slee Novo works well with the AKGs. Drives them effortlessly. I know, it's solid state, but it's designed to work with low impedance headphones and also does not add any 'warmth' to the rather nice treble of the AKG's (at least I find it nice).  I picked one up used for 350 USD.

 

[Kouzelna]

Mellonhead,
 
Do you find there is any problem with the Novo creating any harshness with the high end of the AKG?  I LOVE the K702's high end brightness, but I worry that with the wrong end, especially solid state, it could easily descend (ascend?) into a tinny harshness if not amped just right.  That's another reason I love tube amps with these cans, as it rounds out the high end just a little and warms up the sound a bit.
 
i will check them out, however.

 

[TigreNegrito]

Fairly new here, but I can comment on the HiFiMAN EF2A, which I'm using to drive my Q701's.  I find that it smooths out the more than ample high-end notes (otherwise so high and airy sometimes that my ears cringe).  I can't say that the stock Chinese tubes help to fill in the lower end yet - I think they do, but others may say it's just a relative thing by dampening the high-end.  In any case, listening to the classical genre through it puts me in the conductors position and has given me a far greater appreciation of that type of music.
 
I have other tubes on order, all NOS. Tung-Sols (which I've read here are supposed to really thicken the bass), Raytheons, Mullards (both well-rounded step-ups from stock) and some Western Electrics (no comments anywhere that I can find, just a different brand suggested by the supplier).
 
The amp runs around $150 and tubes are averaging $10/each (the amp needs a matched pair), just to give you an idea on costs.  Like you, I didn't want to invest a lot in a tube amp, and this is more a hybrid amp than a pure tube amp, but I've always wanted to mess around with a tube setup and I found this is a cheap way of doing that.  Everything I've seen here from folks WAY more experienced than myself says that these AKG's are more SS-amp friendly.  They do sound nice when hooked up to my Bithead, but that doesn't really supply the current the Q's need and it clips out at moderate to loud volumes, so I'm going to order the E17/E9 combo.  If you're interested, I'll let you know what I think when these other tubes start arriving as well as the E17.
 
Anyone else out there reading this, if you can point me in the right direction as to how and why tubes work and how one brand will sound different than another, I'd like to learn that, otherwise it's all just anecdotal and trial/error. 

 

[brokensound]

I had great results using the Dark Voice 332 w/ my K701. It gave the K701 a nice punch and drama. They've updated the DV332 to the La Figaro 332s/c and DV 3322. It may be worth investigating how the updated amps pair. Now I have the DNA sonett (MSRP: $1200) and still miss the DV332 at times.

 

[TigreNegrito]

Plus, that Darkvoice looks cool!

 

[Kouzelna]

TigreNegrito I'm totally interested in your findings with the coming tubes.  Please do post!  I'm wondering how different your amp is also when compared to the hybrid Starving Student I'm using.
 
(Thanks, Brokensound, for the Darkvoice suggestion. I ended up looking at those and the Little Dots.  Tempting, but I'm going with Uncle Eric's suggestions for now, and will try those later if I don't like the M-Stage or Objective2).

 

[TigreNegrito]

KouzeIna, check this thread:
 
http://www.head-fi.org/t/497310/hifiman-ef2a-trouble#post_8041624
 
I just picked up a hub, but I haven't tested it out with the EF2A yet because when I arrived home, my order from Fiio was in the mail.  That was just a L9 cable for ipod and a little E6 amp to tide me over till the E17/Alpen hits Amazon.  The point is, I've got the Q's plugged into the E6 and set on the middle bass-boost setting and it actually sounds pretty awesome!  Granted you can't crank it up loud (the little E6 is about the size of a matchbook) but it does drive them ok at low to moderate levels.  Not bad for $25.
 
I am talking to a guy on ebay who is gonna get me Mullards, Raytheons and anything else I want, but he did mention that the 6AK5 family of tubes aren't really audiophile-grade tubes.  That aside, as I said in the link to the post above, there is a big difference between the Tungs and stock, one that I'm very happy with.  Now to see if the usb hub fixes the other issue with that amp.  If it does, I'll order the other tubes and let you know what I think when they arrive.  If it doesn't, I'm shipping the unit back to Amazon and re-selling the extra tubes.
 
You might also consider straying from tubes and look at the three or four E17 threads here and this review over at Headfonia:
 
http://www.headfonia.com/the-upgrade-fiio-e17-aspen/
 
Just based on my initial impressions with the E6, I can only assume the 17 will be as phenomenal as promised.  Plus the whole portability thing.  As I mentioned earlier, these AKG's apparently pair better with SS amps.
 
 
 

 

[Acix]

I'll never recommend tube amp for the K-702, You can check out the Violectric amps (on the warm and can easy drive well the K-702). But if you insist on tube amp, check out the Bottlehead and maybe the DNA.