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my szekerers

post #1 of 19
Thread Starter 
Hi,

I already posted my amp on headwize, but almost forgot that there is another great forum on headphone DIY. So, headwizers have probably already seen this, and are hopefully not too bothered by this shameless crosspost. Here Goes:


++++++++++++++++++++++++++++
Finished my szekerers amp a wile ago. But last friday my parents bought a digicam, so now I can post pics

What's to like:
-easy
-cool
-sounds reasonable for a first project

What's not to like
-no gain
-ugly
-harsness in highs (oscillation, probably)
-no volume pot

What's to do-
-Add gain (still doubts between tubes/SS, I have choice between pc86 tubes and opa627/opa637/opa2132/opa2228)
-make nice case
-add volume pot (already ordered allen bradly 50K)
-replace headphone jack with rca plugs (added those to my headphone to!)

What's used:
Harris irf510
silver caps in signal and mkp in powersupply
rest: bog standard stuff

New amp will look better, use silver cable and will have better layout

Greetz,

Raymond

Pics:



Large complete view



Large topview



Large detail view
post #2 of 19
Wow, weeghel -- nice first post! Links to bigger pics is a very nice touch.

Couple o'questions: What do you mean by "no gain"? And what's hooked up to the heat sinks?
post #3 of 19
heh, thats one mean looking amp nice heatsinks

whats the big block in the back?
post #4 of 19
Thread Starter 
Quote:
Originally posted by jude
Wow, weeghel -- nice first post! Links to bigger pics is a very nice touch.


I've owned a modem once myself

Quote:
Couple o'questions: What do you mean by "no gain"? And what's hooked up to the heat sinks?
No gain: I've buit the stock dc coupled szekerers, so it only amplify's current, not voltage (I hope I say that correctly, but when you check out the article on headwize there's a more correct explanation)

There are two sets of heatsinks: one for the lm317/337 voltage regulators in the powersupply and one set for the harris irf510 mosfets


And let me say one more thing: WOW, a reply in 1 minute?? I first thought that this forum counted my original post as a reply, but i looked to check if the post looked ok and there's already a message
post #5 of 19
Thread Starter 
Quote:
Originally posted by Braver
heh, thats one mean looking amp nice heatsinks
Thanks!

Quote:
whats the big block in the back?
eeeh, you mean the transformer?
post #6 of 19
hoi weeghel,

Nice lookin amp. I want to build an szekeres too, some time in the future. Where did you get that transformer? Is it cheaper than a wall-wart regulated powersupply?
post #7 of 19
Thread Starter 
Quote:
Originally posted by wab
hoi weeghel,

Nice lookin amp. I want to build an szekeres too, some time in the future. Where did you get that transformer? Is it cheaper than a wall-wart regulated powersupply?
Hé hallo, ook nederlands?

Bought it at conrad (www.conrad.nl) Since it was my first diy project I wanted nothing fancy, just everything from one place. Only the yellow capacitors didn't come from there. Someone was kind enough to give them to me. I think this powersupply isn't (much) more expensive than a wall wart.

The layout of this powersupply can be viewed here:

http://headwize.com/ubb/Forum3/HTML/000899.html
post #8 of 19
oh, the transformer so used of seeing battery powered DIY-amps I didn't think of that.

so, what did it all cost you, if you don't mind me asking I'm in the proces of building myself a CMOY, just curious how cost-effective I'm doing
post #9 of 19
Braver, I'd hate to see the batter pack that you'd need to power a szekeres with. And to give you an idea, my cheap cheap szekeres with gain cost about $50, that's using parts from everything and anything I could find, and spending $10 on neat-looking LEDs). I heard that the Cmoy was doable for about $20.

Weeghel, that's a lot of wire there, do you get any interference problems? My szekeres has about the same amount of wire and I have to turn off my computer to use it. Oh, is that wire stranded or solid conductor? From the way it bends I'd say stranded, if so, was it hard to work with? I always wondered if the flexibility of stranded wire was worth the trouble.

You have plenty of extra board space, adding a gain stage would be no trouble.
post #10 of 19
Thread Starter 
Quote:
Originally posted by Braver
so, what did it all cost you, if you don't mind me asking I'm in the proces of building myself a CMOY, just curious how cost-effective I'm doing
That's difficult to say, because in the same order, I bought loads of other stuff and I bought two sets of parts. My guess is, that it's about $40-$50. Never thought it, but the most expensive parts are the heatsinks

Quote:
Weeghel, that's a lot of wire there, do you get any interference problems?
Nope, but it does have other problems. I still think it's oscillating.

Quote:
Oh, is that wire stranded or solid conductor
Stranded. Why would stranded be more trouble? I always thought that solid would be more problematic.

Quote:
You have plenty of extra board space, adding a gain stage would be no trouble
I'm completely dismanteling this amplifier and going to salvage the parts. The new one will be built on a new piece of board and should have a better designed layout. It will also use silvered and less wire. The headphone jack will be replaced by rca jacks. I already replaced the headphone plug on my headphone with a set of rca plugs.

I own a beyer DT-931, and according to J. Meier, this phone sounds best on an amp with an output impedance of 120 Ohm. So I'm considering to give the new amp 2 outputs. One rca output with an output impedance of 120 ohm and one standard headphone jack with a lower output impedance. No idea, however, how to implement this. (my main goal with the rca connectors is seperate grounds for left and right, if I build a standard headphone jack in the new amp, it will connect the two grounds, so I have to figure out a way to add a headphone jack without tying the grounds together)
post #11 of 19
****, I'm spending waay too much on the CMOY excluding the basic equipment, I'm at about 60$ ah well, it's gonna kick but anyways

I'd say solid wire would be easier to use, as you can bend it and it'll stay that way. makes a clearer lay-out.

weeghel, any idea where to get silver wire? or does Conrad carry them (getting a catalogue, should be lots easier to browse than the site..) or something? and are you using one of their PCB's? is it tinned? cause I couldn't find any tinned (or otherwise corrosion-protected) ones.

adding a second (higher impedance) output is a nice idea too. think of doing that as an upgrade later on as well. just to audition the Beyers "properly"
post #12 of 19
Thread Starter 
I don't think you're spending too much. The $40 I mentioned was on parts alone. I did not include any extra costs I made to build the amp (tools/spare parts etc)

I bought the silvered wire off Ebay. There is one dude that has loads of the stuff and posts it rugurlarly on ebay for $9,99 (100ft). The auction ends mostly above that, but when you contact him directly, he'll sell it to you for 9,99 And shipping to the netherlands is cheap too (a few dollars). Had my wire in a week!

look for this email adress: tam at heartmagic.com
(at=@, spam prevention )

found an auction:
http://cgi.ebay.com/aw-cgi/eBayISAPI...tem=1647630475

You can search on his user id to find more auctions.
post #13 of 19
the $60 is parts alone as well

thanks for the wire thing.

still curious what PCB you're using tho . want to get a good one before using expensive wires, upgrade the pot etc etc.
post #14 of 19
Thread Starter 
board: also from conrad. "euro expirimenteer printplaat" with 3 holes that are next to each other connected. I find this the easiest to work with. Can't find it on the webpage, but it's in the paper catalogue though
post #15 of 19
Thread Starter 
Sorry to kick this topic up, but I've finished the Headphone amp page on my website.
I have a website since about 3 weeks now. This is the second page to be finished. I will continue adding info in the coming weeks. I didn't expect that it takes soooooo much time to make webpages
Feel free to comment on the site itself and on the headamp itself

The adress:
raymondaudio

go to projects to read about the headphone amp
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