Time for a new DIY amp...

[slowpogo]

OK, here's another "recommend an amp" thread, except I think I have a pretty personalized vision of what I need.

I built a couple Pimetas, and the second one I really went to town on...diamond buffers, some boutique resistors and caps, etc. It sounded great with less expensive headphones.

But now I have the K701s...they're a pretty good listen with the Pimeta, but I feel they are revealing enough to show me the limitations of the amp. I can tell the Pimeta just isn't doing the K701s justice--I hear better sounds just waiting to come through. BTW, I've been using pro audio sound cards as a source, Echo Mia and then Emu 1212m.

I've heard a PPA, and my Pimeta sounds pretty close in terms of sound signature, though lacking in some other ways. It's rather clean and analytical sounding; harsh recordings sound harsh, while older, warm orchestral recordings sound kind of thin and clinical. I've tried several different opamp combinations, and while some are better than others none of them really free the amp from these basic characteristics. (It has been this way in general with all headphones, not only the K701s)

So I want to build an amp that will mate well with the K701s, and hopefully have the following characteristics:

-- I have done the clean analytical thing, now I'd like something a little sweeter, more liquid and musical. But not at a great expense of detail. My amp now seems to be lacking mid sweetness, so to have that there would be nice.

-- I realize the bass on the K701s is integrated and defined, as opposed to beefy like bassheads would prefer. BUT I'd like the low end to be fairly solid. I'm not a basshead, and I'd prefer that the bass be closer to "accurate" than "exaggerated." But I'd like it to definitely be there, if not in volume than in depth, if that makes sense. If this means a bass boost circuit, that's fine.

-- The soundstage of the K701s is really wide. So in terms of soundstage and imaging in the amp, front-to-back depth is what I'm most interested in.

-- I listen to a wide variety of things, but mostly jazz, classical, and indie/alternative rock (Radiohead, The Shins, Wilco, etc.)

Hopefully the amp would cost not much more than $300 to build (in basic configuration, anyway). After a little poking around, the M3 seems like a contender.

Any other suggestions? I'm excited about building another amp! Feel free to go to town on this one...thank you!

 

[fordgtlover]

I built the M³ to match my K701, and it does. I didn't add the bass boost circuit, and found that it didn't really lack the type of bass I like. I am not a basshead, but I do like solid bass.

I also upgraded from a Pimeta, the M³ allows the K701 to take another step up.

Lately, I have been playing around with the Millett Max. Firstly I built the Mosfet version. With a bit of tweaking it sounded nice. It did everything pretty well including nice solid bass.

I had been informed that the Mosfet version and the 'traditional' BJT versions were quite different, so I built a BJT version of the max and I am very pleased with it. I used the 2SC2238/2SA968 with Nichison ES caps on the tube bypass and output coupling caps. This configuration is very sweet and musical, and adds more bass.

Compared to my M³, the Millett is less detailed, but in my opinion is more musical. I have compared the two using music as broad as Diana Krall, Alison Krauss, Eric Clapton, Sting, Ozzy Osbourne, Whitesnake and Christopher Cross.

I find that I plug in the Max 90% of the time, and when I go back to the M³ I notice the additional detail, but when I then go back to the Max I immediately notice how musical it is.

I really like both of these amps, and they both (all, in fact with the two versions of the Max) pair very well with the K701.

I am running a PC as my source with a Monica USB DAC, and FLAC files.

 

[slowpogo]

Thank you fordgtlover...I have a few questions. When you say you built the M3 to match the K701s, how did you do this?

Also, you say the Max was less detailed than the M3, but more musical. How would you compare the Max's detail to your old Pimeta?

I've been wanting to build the Max for months, but found out too late and have not been able to find a board. The BJT version sounds pretty close to what I'm looking for.

 

[fordgtlover]

What I mean - and should have said - is that before I built my M³ I had read a number of reviews noting the synergy between the M³ and the K701. So, in fact I chose to build the M³ because of it's reported synergy with the K701.

The only thing that I did match to the K701 was the choice of opamps in the M³, and honestly it is a personal preference more than a strict headphone matching issue. I chose to use the AD8610. I liked it in the Pimeta, and after rolling various combinations include 627/637 I always came back to the AD8610/8620. I rolled a few opamps combinations in the M³, but once again came back to the AD8610.

I sold my Pimetas off a few months ago, so I didn't get a chance to compare the Pimeta and Max directly. I can say that using the same Steps power and source the M³ was noticably better than the Pimeta in every way - big wow factor. While I haven't A-B'ed the M³ and the Max, the single thing that does stand out as being better in the M³ is detail. That is not to say that the Max isn't detailed, it just isn't as detailed as the M³. This is more than covered off by the Max being more musical.

Quite honestly, I would have no hesitation in recommending either of these amps. They are both very enjoyable to listen to. They're just different beasts.

 

[stixx]

Quote:

BUT I'd like the low end to be fairly solid. I'm not a basshead, and I'd prefer that the bass be closer to "accurate" than "exaggerated." But I'd like it to definitely be there, if not in volume than in depth, if that makes sense. If this means a bass boost circuit, that's fine.

I'd build the M3 with switchable bassboost...that's what I did after building two tube headphone amplifiers. I'd characterize the M3 as extremely neutral with bass that can't be deeper or better using headphones. The bassboost feature with the values of the capacitors (Cbb) chosen wisely is a nice way of "enhancing" some recordings without making things sound boomy or so...

Otherwise you can always roll the opamps (see my thread here on headfi) to finetune the sonic qualities to your liking.

Quote:

The soundstage of the K701s is really wide. So in terms of soundstage and imaging in the amp, front-to-back depth is what I'm most interested in.

ditto...go for the M3.


From my personal experience so far the only amp to better the M3 is my selfbuilt single ended tube amp using the C3G...in terms of soundstage, naturalness and "sweetness" it's still unrivaled without sounding wooly or "sweet like honey"...in terms of neutrality and bass quality the M3 has the edge.

 

[slowpogo]

So far the M3 seems to be winning out overall. I wonder how sensitive it would be to boutique resistors; maybe a few Riken Ohms in the feedback loop could sweeten the sound slightly beyond "really neutral"?

The only negative is that it doesn't include its own power supply..but the sigma11 can be made for around $70 I'm told.

I'm still intrigued by "tube sweetness" though. Since the Millett Max is for all purposes unavailable to me, are there any other tube amps in similar price that offer similar performance? (This is under the assumption that the Max is a significantly better amp than the trad. Millett)

 

[gtp]

Quote:

Originally Posted by slowpogo /img/forum/go_quote.gif So far the M3 seems to be winning out overall. I wonder how sensitive it would be to boutique resistors; maybe a few Riken Ohms in the feedback loop could sweeten the sound slightly beyond "really neutral"? The only negative is that it doesn't include its own power supply..but the sigma11 can be made for around $70 I'm told.

You could also consider the CK2III: relatively inexpensive, easy to build, integrated power supply, and sounds excellent.

 

[stixx]

Quote:

I wonder how sensitive it would be to boutique resistors; maybe a few Riken Ohms in the feedback loop could sweeten the sound slightly beyond "really neutral"?

Carbon composition resistors throughout could help here...Kiwame or Riken, or older stuff (but then you have to buy a whole bunch to get matching ones..)

Quote:

...are there any other tube amps in similar price that offer similar performance?

Did anyone say SOHA?
A very nice little amp that's sounding excellent and now available with output buffer. Also lets you roll in a lot more different tubes than the MAX...

 

[slowpogo]

Hmm...after some additional searching, it seems like the M3 is a popular choice for the K701 among many. The SOHA looks interesting, and it is tube, but I don't want to mess around with fabricating a circuit board. Also the documentation on Headwize is pretty ghetto compared to the tangent and amb stuff--just one long page.

Any more suggestions are welcome...

 

[fordgtlover]

The Millett Max might still be available from Jeff at Glass Jar Audio.
index

 

[stixx]

Quote:

The SOHA looks interesting, and it is tube, but I don't want to mess around with fabricating a circuit board. Also the documentation on Headwize is pretty ghetto compared to the tangent and amb stuff--just one long page.

There are boards...in fact more boards than for the MAX currently (

)...and Jeff Rossel is selling three kits that seem to be very well put together.

Glass Jar Audio

Also consider this page:

HeadWize Projects - A Simple Tube/Opamp Hybrid Amplifier by Alex Cavalli et al.

PS. I recently was able to aquire a completed SOHA less case with custom output buffer and delay circuit and what not...it doesn't have the mileage of my M3 or tube amp but definitely sounds very promising!

 

[slowpogo]

I did a search for Millett Max group buy, but of course it turns up a million results. I read a while back that another buy was in the works...can anyone give me an update on that?

 

[ericj]

I don't know if another group buy of millett max boards is in the works but i could be talked into selling you one of the two spare boards i have here, plus tubes, sockets for said tubes, and if you like, ultra-bright LEDs to put in the sockets, muse KZ output capacitors, and potentially even a 27vac 500ma transformer and a jameco wallwart enclosure for building the power supply.

at least i keep meaning to sell another minikit, aka kit-of-stuff-you-can't-get-from-mouser.

 

[Uncle Erik]

I'll recommend the M^3, as well. Nice project, good sound, and works well enough with the K-701. I built mine with a STEPS power supply, which cost about $75 or so in addition to the amp. You can use others, but I think it is a good match.

 

[amphead]

The M³ is a wonderful amp, but if you look at which one fordgtlover is using most of the time.....you will love the Max. Especially with BJT transistors, and boutique caps. All under $300.00 with the best parts, and probably under $200.00 with boutique all around. Good luck on a difficult choice.