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I'm back to annoy you all! (I'm going to build an amp--for real this time)

post #1 of 69
Thread Starter 
I've got the money, I've got the time, but I need the info. Since getting my K401's I've realized that an amp is no longer an option; it's a necessity. So here's what I want to do:

1) I'd like to keep this portable. I'm pretty flexible as far as batteries go; with the case I bought a while ago, the pac-tec LH55-130 (I suppose could get a different case if necessary) I can fit an 8 AA battery holder, several 9V's, possibly four C cells, and I might be able to cram 16 AA's in if I get some special holders, but don't count on it. Right now I prefer the idea of eight AA's. The 401's definitely need tons of power, but I don't know how much current they'll need.
2) As far as opamps are concerned, I'm not worried about paying more for really good ones. However, since I'm new to this, I probably should get some cheapos to expiriment with. reccomendations for either would be very useful. I'd like to be sure that my amp has the best components I can get, so I won't necessarily worry about building another (because I might not have the money for a while). For that reason, I also plan to use Neutrik headphone jacks.
3) I want this puppy to look nice! Right now I'm thinking of using an aluminum knob for the volume control (mouser cat#450-6007), and I'd also like a nice looking on/off switch (no "pigtail" switches for me, no way). No idea what to use for that. As far as enclosures go, as I said earlier I'm using a plastic pac-tec case, but if it's possible I'd really like to use a metal case of some kind. Do any nice ones exist, and if so, where can they be found? (From the DIY conversations I've read I'm guessing this won't be possible, or at least not easy.) All this is secondary though, and not totally important right now.
4) I don't need or really even want crossfeed with this amp. So if that's ever a hinderance with some designs, don't worry about it.

Now, here are some questions I have:

1) What type of PC board do I use? I've checked out radioshack but am still confused as to which kind I need. I picked up two different ones but have no idea whether or not they'll actually work.
2) Would an apheared 47 amp work best for me, or is there some other design that would work better with my AKG's? I can't remember if the 47 is optimised for grados or not. I don't want to just build something like a cmoy, I want something a bit more...serious than that.
3) Does it matter what kind of volume pot I use? How do I know if the volume knob I want is compatible? What is the difference between volume pots?
4) Would it be a good idea to use RCA connectors instead of a minijack for the line-in, or is that going to far? One plus is that it would go well with a home CD player (if I ever got one), and I could use higher quality cables...
5)

Those are my basic questions...I may remember more as I think about it.
post #2 of 69
The 47 is definetely meant for low-impedance phones like the Grados. Aren't your AKGs little high-impedance monsters? Maybe you should try Apheared's Senn. 600 amp.

(coolvij officially runs away from this DIY thread.....he has no knowledge about this topic; likes talking, though )
post #3 of 69
Uh excuse me Mr. I-haven't-built-****-yet-in-a-year... Don't say the CMoy isn't "serious" until you build at least one.

post #4 of 69
Neruda, I am in the process of building my first amp too, so I had the same questions as you.

1) I am using a PCB with copper strips with 3 "holes" in them and it also has one ground strip with lots of holes in it so I can easily ground everything.
2) You don't think a cmoy is serious? And isn't a "Apheared 47" just a cmoy with a few modifications? I think the cmoy is an awesome design! and you can modify it to suit your needs (optimize it for your phones, add crossfeed of choice etc.).
3) It doesn't matter much as long as it has the right value (50K, 100K etc.) and fits your enclosure.
4) That's a matter of personal preference. I am gonna use mini-jacks to keep it as portable as possible.
post #5 of 69
Have you considered the SDS Labs Headphone Amplifier?

Oops--I guess this one isn't too portable. But it is more "serious" than the cmoy.
post #6 of 69
well dude it is WAY past overdue

I suggest you do the standard cmoy amp for your first go at DIY

Don't overload your butt just yet !

standard off the shelf radio shack pcbs,casing,switches,metal filmresistors and caps are fine for this project.

op-amps ?

chooses yer poison , but I would start with the opa in the article first,socket it and then when you KNOW the sound,over time,then it is playtime (but do not be surprised if you come back to stock !)

start out with a gain of X7 or so and either go with dual nine volt batts or an AA pack of 16

wiring-I like individual strands of CAT-5 network cable.Good stuff and easy to work with

Fancy switches ?

Toggles are some of the best sounding and most reliable made !
you want top notch ? Do mil-spec silver toggles

you want a power "on" LED ? Do low current

you want to bump up cap quality a tad-orange drops will not let you down,though the big blue rat shack mylars are not bad-really

output jack-nuetric on a portable ? your amp man but these suckers are BIG,really BIG !

your choice dude


so my choice for a first amp

hansen pcb,for ease of assembly
leave out the xfeed,
dual nine volt batts,mylar caps,
generic metal film resistors,
toggle switch-dpdt center off side 1=dual 9v/side 2 =ext battery pack
rat shack/alps dual 100k pot (next resistor 1meg)
OPA2134 gain of 7 or so,maybe 10--socket it
rat shack metal over plastic knob
stock rat shack "open circut" 3 conductor 1/4" phone jack
RCA input jacks

build for about 30 bucks

live with it

let version 2 be the bomb

you gotta crawl before you walk and walk before you run man

way of the world

rickster
post #7 of 69
Neruda,

PM me your mailing address, I'll send some op-amps your way to get your started.
post #8 of 69
Thread Starter 
**** you apheared.



I tried to make stuff, I really did! But I didn't have money, and you damn people lied about the cost! I was thinking, "oh yeah, I'll get all the stuff for about $50 and make an amp, no sweat." then I get only a few of the things I needed and you people are like "oh yeah, well, if you're just starting then it's going to cost you a lot. and oh yeah, you'll also ned such-and-such, and that's going to cost you $20." Bastards!

Well, I do have a hansen PCB rick, so at least that gets us somewhere! I guess I should start slow, huh? Still, like I said in my above rant, I don't trust you people when you say it'll cost me $30, I've already spent more than that getting only half the crap necessary!

wab, I think I bought the same pcb as you, as well as a second one with no copper strips.

JMT, will do, and thank you tons!
post #9 of 69
More than $30 already? Did you have to buy a soldering iron? I've been using my uncle's while I've been out here in California, but it looks like I'm going to need to buy my own once I head back home. Though it's the cost of a decent multimeter that frightens me.

I think I ended up spending around $23 on the components for the CMoy I built (my first one). That doesn't include tools (which I borrowed), wire, the small piece of vectorboard I used, or the interconnects, or the battery / AC adaptor. 'Course, I used extremely generic parts; I skipped over ratshack and went with a local electronics surplus supply store (I think one of my capacitors is bad, stupid cheap components).

Argh, I'm going to have to buy a set of tools to do this stuff at home. I still have enough opamps and dual pots to make 3 more amps. Darn digikey's $5 service charge on orders less than $25!
post #10 of 69
Thread Starter 
yeah, I had to buy a soldering iron and all that crap. And I still need to buy a multimeter...
post #11 of 69
Neruda,

Those Neutrik jacks are freaking scary, but I could send you one if you really want it...I don't think I'm ever going to take the time to mount the beast on anything! It weighs more than my amp does. I too thought I would get the best parts to start out with, then when that beast of a headphone jack arrived I got scared. It's been whispering mean things into my ear, keeping me awake at night, begging me for a metal enclosure.

I agree to keep it simple, and don't be scared to use those retro toggle switches. People really do love how they look, even normal people it seems. I also used that Radioshack board with the 3 hole pads. Worked great. You can get almost everything at radioshack, although I would probably get the digikey panasonic pot because it's pretty small, and the spring-loaded headphone jacks from mouser. Radioshack has switches, gold-plated RCA jacks, low current led's, wire, pcb, IC holders, AC adapters, battery holders, etc.

Good luck!

--
Scott
post #12 of 69
Thread Starter 
Some people (or a lot of people) may like those toggle switches, but I don't. I have one. I think it's evil.
post #13 of 69
Evil ?

IT'S A DAMN POWER SWITCH FOR GAWDS SAKES !!!!


Rickamundo

BTW-hey jude (where'd I hear that before) , where is my damn evil smiley

post #14 of 69
Hey JMT, how do I get on your free opamp mailing list?
post #15 of 69
Thread Starter 
I want to get on his free amp mailing list!

C'mon rickmeister, cut me some freakin' slack! I hate toggle switches, okay? Everyone's just going to have to deal with it! Well, I suppose I could use one on my first amp, expecially if they're easy to get. And I suppose I can drop the neutrik jack. (insert nonexistent pouting face here)
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