[V-DiV]

After getting my start in DIY last summer I've been too busy to continue for months. Now I have some free time again to actually put together my Starving Student and at least put together the order for my next project. What are the best amps for the hard-to-drive AKG K701 headphones? I listen mostly to classical and jazz these days and I would like an amp that maintains the clarity, soundstage, and sense of air inherent in these cans but also fills out the bottom end better. I was planning to build a Soha II next, but is there another DIY amp better suited to the K701 (Millet Max, CKKIII, M^3, B22, Bijou)?

Thanks

 

[Wilf]

I can recommend the amp kit from Jaycar electronics in Australia.

http://www.jaycarelectronics.co.uk/p...p?FORM=KEYWORD

Amp is part number kc5417 and the psu board kc5418.

Massively good value for money, and very straight forward to build.

By adding a LM4562, improving the PSU by implementing a capacitance multiplier, and a few more mods, I have an extremely detailed, refined and musical amp. It better than several of the amps you have mentioned (except the B22, not heard that one), all in comparison, using my K701. The amp drives the K701 easily.

 

[V-DiV]

Quote:

Originally Posted by Wilf /img/forum/go_quote.gif I can recommend the amp kit from Jaycar electronics in Australia. http://www.jaycarelectronics.co.uk/p...p?FORM=KEYWORD Amp is part number kc5417 and the psu board kc5418. Massively good value for money, and very straight forward to build. By adding a LM4562, improving the PSU by implementing a capacitance multiplier, and a few more mods, I have an extremely detailed, refined and musical amp. It better than several of the amps you have mentioned (except the B22, not heard that one), all in comparison, using my K701. The amp drives the K701 easily. Full details over at the Rock Grotto forums, look for the Jaycar section. (google it!)

Thanks Wilf. But its hard to believe that such an inexpensive kit could make hi-end sound and stand up to the more complex amps I mentioned. I haven't had time to pour through the Rock Grotto forums enough to get serious impressions of the sound quality compared to other amps.

 

[grenert]

I have the K701 and a PPAv2 made by Tangent himself. The PPA is a very revealing amplifier. I changed out the opamps in mine to AD825 all around, and added rail-to-rail bypasses to the underside of the board. It has a very clean sound to it, wide soundstage, keeping in line with the headphones. With bass-light sources, it is nice to have the bass boost knob, which can be made to be subtle yet effective. With a better source, I don't use the boost at all.

 

[holland]

Honestly, any of the popular amps can drive the K701. It's not really hard to drive, as that's a common misconception that's prevalent.

M^3 and PPA has bass boost. You may need that.

Edit: Bijou is all tube, that may bring some life to the K701. With the right tube pairings you can get some real bloom in the low-mid.

 

[compuryan]

check out glassjaraudio.com. they sell a lot of kits, I've bought one myself. The millet max and soha kits are complete with enclosures, potentiometers and absolutely everything. It'd be a convenient option.

 

[V-DiV]

Thanks grenert and holland for the comments on the PPA and M^3. I wondered if the bass boost circuit would tend to add some distortion. Grenert, what kind of music do you listen to with your K701/PPA combo and are you perfectly happy with the sound? Holland, I was thinking that a hybrid like the Soha II or Millett Max would give the bass oomph of SS plus some tube magic without needing to fiddle with high voltage, though I would fiddle (carefully) if I got the impression that the Bijou would be a great match for the K701. Compuryan, I have ordered stuff from Jeff at Glass Jar once or twice before and that is a great way to save time.

 

[slowpogo]

I use the Millett Max with my K701s, and it's great. The K701s are very neutral so for me anyway, a little sweetening is necessary. Try it with Riken Ohm output resistors. Cerafines sound very good with this setup too, if you can find them (try ebay).

 

[MrSlim]

I think a SOHA with JISBOS buffers is an excellent route for you to go. There's a thread with a comparison review of the SOHA+JISBOS vs the SOHAII and the SOHA still compared quite favourably to the SOHAII(in that persons opinion). Adding the e12 for output protection is also a good idea.

 

[nsx_23]

Do the kits from glassjaraudio come with cases with the holes already pre-drilled? I'm interested in the SOHA kit.

 

[grenert]

Quote:

Originally Posted by V-DiV /img/forum/go_quote.gif Thanks grenert and holland for the comments on the PPA and M^3. I wondered if the bass boost circuit would tend to add some distortion. Grenert, what kind of music do you listen to with your K701/PPA combo and are you perfectly happy with the sound?

I have not noticed any distortion with the bass boost. Most of the music I listen to is rock, jazz, classical. I only use my amp/headphones by the bedside, where I do not have room for a very good setup. So, the best source I have is a modded DCP-150 PCDP. While it is nice for a PCDP, it is not as good as a nice DAC. I think it is the limiting factor in the setup, rather than the amp. I need to use the bass boost with the PCDP. I will say, however, that the default OPA637 and OPA627 opamps were not to my liking. They seemed "muddled" and did not have the clarity that I get with the AD825. I highly recommend the AD825 if you build this, and, like I said, bypass across the rails with a nice 0.1uF capacitor (C0G). Note that the AD825 only comes in a SOIC package, so you'll need to put them on an adapter board. Some folks say that Aries are better than Browndog (less convoluted traces), and I went with Aries adapters for my amp.
I would be surprised if you could be disappointed in it. I can tell that my ears are definitely biased toward the PPA design. I have owned several well-regarded portable amps (Mini^3, Porta Corda III, Super Mini IV, PPAS), and the PPAS (a portable amp based on the PPAv1) is my favorite.

 

[fordgtlover]

I can verify that the K701 sound great with the Millett Max, M³ and Bijou. My Pick at the moment is the Bijou because I'm on a 'tube thing', but I would have no hesitation recommending either of the other two.

One of these days I will go out to Jaycar and buy one of their amps. They come highly recommended.

 

[holland]

Quote:

Originally Posted by MrSlim /img/forum/go_quote.gif I think a SOHA with JISBOS buffers is an excellent route for you to go. There's a thread with a comparison review of the SOHA+JISBOS vs the SOHAII and the SOHA still compared quite favourably to the SOHAII(in that persons opinion). Adding the e12 for output protection is also a good idea.

You mean this thread? http://www.head-fi.org/forums/5143237-post281.html SOHA II, IMO, will be cheaper, as it's all in one. It has a better buffer and a better tube configuration, IMO.

V-Div, yes, you would get some of the tube magic with a hybrid. You won't, IMO, get as much as with pure tubes. Pure tubes will cost you more in the long run, though. Tubes are quite pricey, if I do say so...especially the ones people rave about.

Unfortunately, I don't have a K701, but I think one of the Bijou builders does. Fishki13. You may want to read his impressions. I think he's heavily into jazz (proper, not the modern jazz/new age stuff) as well.

Note, the Bijou, though simple in parts, is a bit more advanced in terms of build. Though there are PCBs, it's not all in one, and you have wiring and grounding to take into consideration. It makes it a bit easier than point-to-point. The case work and parts selection will be where it lies, and the cost can be pretty high. I'm using all MKP on mine, and I'm still building it, but I think I'm at about $700 for the build so far without a custom panel. The caps taking half of it. I'm not taking into account all the tubes I bought so far. I'm not sure how much a barebones build is.

 

[V-DiV]

Quote:

Originally Posted by fordgtlover /img/forum/go_quote.gif I can verify that the K701 sound great with the Millett Max, M³ and Bijou. My Pick at the moment is the Bijou because I'm on a 'tube thing', but I would have no hesitation recommending either of the other two.

Have you spent enough time with those three and the K701 to be able to point to sound differences between them, their strengths/weaknesses?

So PPA / M^3, Soha+Jisbos, Millett Max, and Bijou all have positive votes. Has anyone spent time with K701 and either Soha II or B22?

Quote:

Originally Posted by holland /img/forum/go_quote.gif You mean this thread? http://www.head-fi.org/forums/5143237-post281.html SOHA II, IMO, will be cheaper, as it's all in one. It has a better buffer and a better tube configuration, IMO. V-Div, yes, you would get some of the tube magic with a hybrid. You won't, IMO, get as much as with pure tubes. Pure tubes will cost you more in the long run, though. Tubes are quite pricey, if I do say so...especially the ones people rave about. Unfortunately, I don't have a K701, but I think one of the Bijou builders does. Fishki13. You may want to read his impressions. I think he's heavily into jazz (proper, not the modern jazz/new age stuff) as well. Note, the Bijou, though simple in parts, is a bit more advanced in terms of build. Though there are PCBs, it's not all in one, and you have wiring and grounding to take into consideration. It makes it a bit easier than point-to-point. The case work and parts selection will be where it lies, and the cost can be pretty high. I'm using all MKP on mine, and I'm still building it, but I think I'm at about $700 for the build so far without a custom panel. The caps taking half of it. I'm not taking into account all the tubes I bought so far. I'm not sure how much a barebones build is.

I had seen that comparo by FallenAngel on the Soha - Soha II. I think I also remember some of Fishski13's short comments on the Bijou with K701 (I must be spending too much time around here).

The Soha II or Millett Max can be built relatively inexpensively. The Bijou kit at Glass Jar is only $173 without transformer, case, and jacks. I guess it's the boutique parts that make it expensive, and sound the best. I will likely build my own case or cannibalize something.

 

[holland]

^^ shipping + paypal fees too, so assume about $185. The transformer is on the heavier side of parts, so assume about $70-$85 if you get it from Jeff. So you can see, you're now @ $260 without a case, jacks. I didn't get the kit from Jeff. Some things are similar though. Caps set me back about $350. A bunch of little things for the way I want to mount parts and setup the case.

Jeff's kit is definitely on the cheaper side of things. I probably should have gone that route and just leave out things I didn't want.

People tend to look at the kit prices and think that's it, but it's really a bit more than that especially for the more free form builds.

SOHA II and MM will be cheaper to build as they are more restrictive and transformers or wallwarts are cheaper.

Edit: knobs too.