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Altoids Headphone Amplifier - Page 3

post #31 of 48
8/4/01 at 11:15am
JMT, I have a few questions. How long does it take you to build a Altoid amp? I know you built quite a bit already. Do you build it the same way every time or do you experiment with the design of the layout to perfect it? Really nice amp!
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post #32 of 48
8/4/01 at 12:26pm
I've just remembered I have an Altoids tin that has been knocking around our car since we bought it. (Curiously Strong Peppermints ) Looks like a good home for my second Hanson. But I need a 3 pole 3 way switch for the Xfeed (I used a 2 way 3 pole two on the other). Any suggestions would be greatly appreciated!!
crk
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post #33 of 48
8/4/01 at 1:28pm
Quote:
artmusic247 wrote

JMT, I have a few questions. How long does it take you to build a Altoid amp? I know you built quite a bit already. Do you build it the same way every time or do you experiment with the design of the layout to perfect it? Really nice amp!
artmusic247:

Thank you. If I have uninterrupted time to sit at the workbench (which is rare) I can get one done in about a half a day. If I am building for other people, I build it pretty much the same way to ensure consistency in the sound. If I make it for myself, I do a bit of experimenting.
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post #34 of 48
8/4/01 at 6:00pm
Quote:
Originally posted by flight
Would there be any chance of getting the schematic and possibly a parts list for this wonderful amp?
I'd like to see one as well if possible.
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post #35 of 48
8/4/01 at 6:04pm
flight-

the amp was designed by Apheared, he posted it at headwize but the forums are currently down. So email him for the schematics.

I think the design was based around CE Hansen's PCB, which you can get by contacting him. I've never used his boards but i think they include a parts list...

All of these designs are modifications of CMOY's original pocket amp, which you can find at headwize's libary...
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post #36 of 48
8/4/01 at 8:07pm
Actually, the design is based around the cmoy pocket amplifier (which is very simply just an op amp w/gain setup with a high-pass filter at the input and extra resistor to deal with possible noise. CE Hansen designed a PCB layout based on a circuit by Jasmin Levallois (which is a cmoy/op-amp gain stage at the front, incorporates the Meier crossfeed circuit in the middle, and has an op amp at the output). Apheared's "47" mod is the basic opamp gain stage (that we all call a "cmoy") but with parallelled op amps which is what makes it so special. Building the "47" with a Hansen board just makes it easier, since the "cmoy" portion is already set up. You end up using only a portion of the board though. You could actually save space and make a smaller amp if you put the "47" on your own board (e.g. basic holed boards available at electronics stores). In this way, you could fit 2 9V's in an Altoids tin.

Link to Levallois circuit on a Hansen board:
http://headwize.com/projects/cmoy2b_prj.htm

Link to Apheared's "47" circuit:
http://headwize.com/projects/apheared_prj.htm
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post #37 of 48
8/4/01 at 8:43pm
I had a period of building Lamps out of thin aluminum and steel. (actually I still do it just not as much) As aluminum is softer than tin it is even easier to tear the metal when drilling it. Personally I found that using Titanium Drill bits is the first step to getting good holes. I am not sure what JMT meant by going slowly but I found that you need to keep the RPM's up a bit, around halfway on my drill (500-600 rpms) or in some cases 3/7ths (350-450), and apply light pressure at a perfect 90 degree angle. If by going slow he meant don't push too hard then yeah I would have to agree... I used a compass point to make my starter dents.
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post #38 of 48
8/5/01 at 1:52am
I can't find the Apheard 47 Sennheiser HD-600 thread that I know exists.

If someone would be so kind as to make a link to it in this thread then I would be greatly appreciative.

Also, does anyone know if that particular project will fit into a mint box?

Thanks.
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post #39 of 48
8/5/01 at 2:33am
The apheared 47 thread was poted at headwize, which currently won't display posts older than 30 days...

The amp will fit fine in an altoids tin (or even a 9V battery/film container- see skippy's amp) though you can do more interesting things with the layout and topology if you use blank boards rather than CE hansen's boards. But those premade boards are easier to work with...

If you're referring to apheared's new amp designed for the HD600's, then look back a few days in the DIY forum. Its an AD823 gain stage paired with an Elantec EL2001 buffer. See CMOY's designing opamp based HP amps article to find different ways of designing amps with seperate gain and buffer stages...
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post #40 of 48
8/5/01 at 2:39am
Here is the link to Apheared's HD600 Cmoy variant:

HD600 - Cmoy
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post #41 of 48
8/5/01 at 2:54am
Thanks JMT
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post #42 of 48
8/6/01 at 1:20pm
Out of curiosity, JMT, do you take orders for headphone amps from Head-Fi'ers, and if so, how much do you charge? That is a truly cool amp.

I would be interested in making my own, but I'm not sure I have the time and/or equipment, and I'm sure it wouldn't look nearly as nice.
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post #43 of 48
8/6/01 at 1:26pm

hey...wait a minute!

That altoids amp is identical to my amp - except mine is in a Penguin case.....hehehe....
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post #44 of 48
8/6/01 at 1:54pm
Has anyone used one of these, or a variation, with Etys (ER4S)? JMT and I were discussing this, and I did a search but didn't find anything. I'm curious as to whether this version, good for Grado's, but not for HD600s, would be the best version for a set of ER4S's...
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post #45 of 48
8/13/01 at 4:18pm

Etymotic

This is my first post, but a comment on the Ety's from what I am learning in my quest for either the 4P, or 4S (amped). The ER 4S is a 100 Ohm impedence headset, so they may be tiny, but low impedence they're not. I'd imagine they'd benifit from a design that was closer to the, also high-imped, Senn's (HD600=300ohm, no?).

Any comparison to this design verses the Headbanger (Laff.) setup? If one goes with the Ety's, what works best for low $$.

FWIW, the ER 4P's are about 28 Ohm and work more like Grado's, I suppose. Any user comments?

Chris W
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