[nightanole]

I work in a esd lab so our only fun is headphones. We swap amps and headphones as we get new toys in. Well i went out and built a starving student. It sounds very good with my 770pros 80. the problem is that it runs too hot for lab work (tubes get hot?) so im looking for something new.

I got my choices down to:

both of these dont seem popular right now;
The Cavalli-Kan Kumisa III Stereo Headphone Amplifier
The M³ Stereo Headphone Amplifier

ppa v2

maybe a steps power supply


the problem is i dont have a bom on any of these to see what i can afford (steps=$70 but cant find were to order the board). Since most of these run class A, would like to know how hot they get since i dont want to be stuck with a 45c amp.

In other news i also would like some info i a goodish dac for $25-75. So far in that range is only the pcm2702 style ones and they all look the same. Im not sure if they are better then just notebook headphone out, or if i should stick with a unmodded ipod nano lod.

 

[tomb]

A PCM2702 DAC is light years ahead of a notebook headphone out.

As for your other comments:
STEPS has been discontinued by Tangent. His TREAD has essentially equivalent performance and is a lot smaller. You can add more power caps to it with just a bit of difficulty, making it essentially equivalent to the STEPS. You can build one just to use a standard 24VAC walwart. His Young-Jung Super Regulator is his new design, but I think it's still undergoing prototyping.

The CKKIII, M3, and PPAV2 are all excellent amps - don't know why you'd say they're not popular.

Both the M3 and PPAV2 are signal-stage opamp-based, with a Class A discrete buffer output. The PPAV2 uses BJT's in a diamond buffer arrangement while the M3 uses complementary MOSFETs. Both can be powered by the TREAD, but the M3 will do better with AMB's Sigma11 supply since the MOSFETs are biased to relatively high currents. The M3's heat sinking and heat will be similar to the Starving Student, while the PPAV2 and CKKIII use BJT's on the output without heat sinks. In the case of the CKKIII, you can attach heat sinks for a higher class A bias, if so desired.

Both the M3 and PPAV2 use active ground channels, which is supposed to be as close as you can get to a balanced amp without building one. Of the three, the CKKIII is a slightly different animal, based on a discrete feedback-less design. You'll have to construct your own power supply with transformer since it's based on 2 x 15VAC supply.

Note that the regulated power supplies for any of these amps will carry a significant heat-producing, heat-sinked regulator. Even the CKKIII has heat-sinked regulators, although they're on-board and can withstand being internalized in a case without air circulation

There are many people more infinitely familiar with these amps than me, but hopefully I summarized the general differences accurately.

 

[MrSlim]

Check out AMB's website here: AMB Laboratories DIY Audio Site
He has the BOM's and Boards for both the CK2III and the M3.
At the moment, they might be seem to have lower popularity than other amps, but that does not make them any less good. Tube amps and Hybrids are in vogue at the moment (Im in the CTH proto group), but for solid state amps in that price range, the M3 and CK3III are the best, and you won't find many arguments in that regard. The M3 is based on the PPA v2 I think, but I think most people would say the M3 is better.
The CK2III is going to be an easier build because most of the Power supply except for the transformer are included on the board.. so it can be done in one box. the M3 can be done in one box too, but a lot of people are doing it in 2 boxes..
I think you are going to get better sound out of one of the 2702 DACs vs notebook out. I have a Silverstone EB01 that is pretty decent, that I paid under $100 for. I think its a good starter DAC..
Another option would be to do a DIY dac, with this 24bit/192Hz HI-FI DAC DIY KIT , ASSEMBLED MODULE - eBay (item 140307442774 end time Mar-19-09 21:43:30 PDT)
Check out the "NoodleDAC" thread for mods and build ideas..
You could build something pretty nice for under $150 if you kept the case simple..
If you want to get crazy with it, google Lampiztor for a website that has mods for the board also..

 

[nightanole]

So most of these amps are going to be just as hot running as the starving student? Guess i will have to make an opamp based unit if i cant find a cooler running a/b amp.

 

[tomb]

Quote:

Originally Posted by nightanole /img/forum/go_quote.gif So most of these amps are going to be just as hot running as the starving student? Guess i will have to make an opamp based unit if i cant find a cooler running a/b amp.

Well, the PPAV2 and CKKIII run cooler, but again - when you include a linear-regulated power supply, things can heat up fast.

The feature you're trying to get around is Class A biasing. Commercially, this is available on only the most expensive equipment because of the larger power supplies required and the heat sinking/cooling requirements. However, it's relatively easy to implement in DIY. Consequently, it becomes almost a minimum threshold for DIY designs - at least for a desktop amp.

You'll need to get into portables if you really want something to run cool. Even with DIY portables, battery life is an important consideration and Class A operation is a battery killer. So, things will run cooler.

They won't match the performance of a good desktop, though.

EDIT: You may want to check out Tangent's PIMETA V2. The design thread is active right now on Headwize:
http://headwize.com/ubb/showpage.php?fnum=3&tid=7727

 

[kvant]

Quote:

Originally Posted by tomb /img/forum/go_quote.gif The M3's heat sinking and heat will be similar to the Starving Student...

It should not be that bad... simple estimates based on output stage only:

Starving student:
(48V supply) x (0.15A through output stage) x (2 channels) = 14.4W

M3 (default setup):
(24V supply) x (0.08A through output stage) x (3 channels) = 5.8W

PPA (default setup):
(24V supply) x (0.02A through output stage) x (3 channels) = 1.44W

To reach the same heat production with PPA+regulator as with Starving student, you would have to drop about 13W/0.06A=217V on the regulator. That is not very likely, so I would say that PPA would be a noticeably cooler-running solution compared to Starving student.

 

[Beefy]

Quote:

Originally Posted by nightanole /img/forum/go_quote.gif In other news i also would like some info i a goodish dac for $25-75. So far in that range is only the pcm2702 style ones and they all look the same. Im not sure if they are better then just notebook headphone out, or if i should stick with a unmodded ipod nano lod.

Have a look at the y1 DAC. A 'Lite' build with just USB input should be do-able inside that price range.

A matching mini3 would be your best bet for low heat production, or you could go a CKKIII for something a bit more powerful.

 

[Juaquin]

Another vote for the PPAV2. You don't have to Class A bias it anyways.