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DIY HiFi IEM amp

post #1 of 18
3/8/11 at 9:33am
Thread Starter 

Hey Guys,

as in the title, i am looking forward to make a small amp, that drives my IEMs, currently the RE0s. the following have to be kept in mind

i) should be small (comparable to the iBasso T3)

ii) Should be hifi or high definition or i guess transparent, whatever possible

iii) i am planning using an internal rechargable battery, so it should be able to run off 3.7volts or more less than 9volts

 

if not already documented, you guys can come up with new amps, it just needs to sound good, and should be portable in every sense of the word.

 

and i have searched on Google, couldnt find anything.

 

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post #2 of 18
3/8/11 at 10:28am

Did you have a look here, or here?

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post #3 of 18
3/8/11 at 10:35am
Thread Starter 

thanks man, but i did look up both the links, am looking for something more small scale. :) truly portable.

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post #4 of 18
3/8/11 at 11:04am

it is good to "do the numbers"

 

I see 64 Ohm, 100 dB/mW for RE0

 

typical 1 Vrms output portable players will drive these to ~112 dB SPL

 

that is in most people's estimate more than loud enough for "casual" listening or extended listening time - if you're using them hrs a day you want average SPL <<90 dB and there are few recordings with >20 dB peak-to-average dynamics

 

I can understand wanting to "do something" but a portable amp for these doesn't make much sense - considering that most diy (and cheap commercial) portable amp projects use technically worse op amps for the purpose of driving low Z loads from low V supplies - the portable player manufacturer's are using purposed designed output amp parts and battery management chips

 

to beat them on quality AND keep size down with diy build techniques is asking a lot

 

 


Edited by jcx - 3/8/11 at 11:05am
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post #5 of 18
3/8/11 at 11:05am

So the long version of my post was deleted (bloody school internet), so here's the abrided version.

 

First, the two amplifiers mentioned above do fulfill all of your conditions.

If you're looking for anything smaller, you might want to look into a basic CMOY, or try doing some SMD soldering with different components.

 

 

As far as sound quality goes, the Mini^3 performs well as you can see here:

http://www.head-fi.org/forum/thread/214588/review-portable-amp-roundup-56-portable-amps-reviewed-and-compared-final-update-12-20-10-added-rsa-sr-71b (search Mini3)

 

On the plus side, all of the projects mentioned above are really popular and you really, really want good documentation...documentation is gooood

 

Judging by your previous posts, I think it would be BEST if you read this article here which sums up some of the important considerations before considering DIY-work.  If you can't justify it, then I would not suggest you to do it:

 

http://sound.westhost.com/why-diy.htm

 

If you're not sure, there are several commercial amps (highly portable) that you can consider that would be even cheaper than the parts needed (soldering iron, solder, power tools, hand tools, etc.) even without the project parts included.


Edited by Bop - 3/8/11 at 11:08am
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post #6 of 18
3/8/11 at 11:16am

Small Transformer FTW.

 

adsc_0006.jpg?t=1299611642

 

The battery clip and LED are for design obfuscation purposes. Its just 2 small transformers between the headphone output of the ipod, and the headphones.

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post #7 of 18
3/8/11 at 11:21am
Thread Starter 

Guys, i dont understand why is everybody on my back about this DIY and saving money thing? look, i have enough of the DIY spirit, i mean my first project was a blinking LED reading one of the books my Dad had. i wasnt saving money that time, then i remember a Headphone Limiter, then a HeadBanger, actually 2 headbangers, a CMoy. Cant i want  my CMoy to sound better then the T3 they put up on the iBasso website? isnt that like saving money? am not going to cut short my list of components/good components needed to work the amp out. i want to save money in this sense, making my amp sound better than maybe the $400 amps at maybe $350. i saved money, coz well, shipping charges. Guys i dont lack the DIY spirit, niether do i need to ask myself if i want to DIMyself, or READ WHY DIY (interesting Read though) i've been doing this stuff for a long time, money is a problem and i am still making amps happen. currently arranging for the Mini3 parts too. i just dont wanna spend crazy on prebuilt amps, thats it. Please dont mind guys, i really appreciate your help, but i know what i am doing.

 

Hey Bop, dont we have something that can fit into the FiiO E3 maybe?

 

And for God's sake, i have my own Soldering Iron/ Solder Wire (Hehe) and a few protoboards from waiting-to-be-done Projects.

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post #8 of 18
3/8/11 at 11:23am
Thread Starter 

Seriousky nikongod? that works????

what transformers are they? what exact readings? this is something coooool.

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post #9 of 18
3/8/11 at 12:09pm

Yes, it works. low output impedance, a nice easy load for the portable player (the output op amps they use generally measure better into higher impedances) and it burns some gain, which is nice so you dont have to attenuate so much digitally. If you *need* the full swing from your player It wont cut it, but very few people really do.

 

They are cheap 1K:8ohm transformers from Radio-Shack. I think Xicon makes similar units sold through mouser. They are like $3 each.

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post #10 of 18
3/8/11 at 3:38pm

Ah sorry, I was basing my post off of a previous post.  The Fiio E5/E1 uses 100% SMD components so unless you want to go SMD, I would say no...on the contrary, there are some affordable portable budget headphone amplifiers (haha)...well it looks like you've settled on the mini^3 project, have fun and good luck~ 

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post #11 of 18
3/8/11 at 11:58pm
Thread Starter 

Has anybody tried making  the Mini3 here? any  twaeks available on the mini3? i need to order everything at the same time, so staying safe for the future. any tweaks are welcome, better caps, better resistances (would they make a difference?) and anything else.

 

Thanks

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post #12 of 18
3/9/11 at 2:45am

you do realize there is a search feature here right? and several threads about the mini3, one even on the first page. given your list of wants i'm really not sure you DO know what you are getting into. hifi from 3.7-9v in a size of the E5/E1?..... this limits your opamp choices massively

 

 

 

@nikongod: cool cool.gif


Edited by qusp - 3/9/11 at 2:47am
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post #13 of 18
3/9/11 at 7:15am


Love it! Did you use the wiring scheme PRR suggested on another forum?

 

Here's mine, along with a wiring diagram and how-to: http://beavishifi.com/projects/Passive_IPOD_Preamplifier

Quote:
Originally Posted by nikongod View Post

Small Transformer FTW.

 

adsc_0006.jpg?t=1299611642

 

The battery clip and LED are for design obfuscation purposes. Its just 2 small transformers between the headphone output of the ipod, and the headphones.



 

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post #14 of 18
3/9/11 at 7:54am
Thread Starter 
Quote:
Originally Posted by psgarcha92 View Post

Hey Bop, dont we have something that can fit into the FiiO E3 maybe?

 

@qusp, i guess i said E3 man.at this stage i can fit a CMoy into an E3, rechargable batteries included (But CMoy isnt HiFi, not even with the best caps and resistances), so i guess am not asking for much. i do know there is a search button, and i know how to use it, can u please do the searching for me and find something that i specified in my post? its all named below:

i)Size Comparable to iBasso T3 or FiiO E3 (Which i think is not E5 or E1, seriously please read the posts atleast)

ii) is HiFi (here i was inviting ideas, not just pre-built designs)

iii) can be rechargable.

 

also, the datasheets give enough idea of the operating voltage, and have u seen those small mp3 player chinese batteries? they are smaller then the T3 battery in size, and 300mAH i remember. please read and then reply.

 

@nikongod? is it hifi? coz it is way too WICKED.hehe
 

 

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post #15 of 18
3/9/11 at 11:02am

I quite like it, but if you are interested in how it sounds you should invest $10 and an hour of your time in building one. After that you can decide for yourself. 
 

Quote:
Originally Posted by danobeavis View Post


Love it! Did you use the wiring scheme PRR suggested on another forum?

 

Here's mine, along with a wiring diagram and how-to: http://beavishifi.com/projects/Passive_IPOD_Preamplifier


Nope, The PRR circuit is wired as a step-up autoformer. My circuit is wired as a step-down transformer. 


Edited by nikongod - 3/9/11 at 11:17am
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