[timmyGCSE]

this will be my first amp build, my idea is to a) save money (I'm poor at the moment, can afford about £40 tops) b) get into this as a hobby.
I've done a small amount of electronics and soldering and circuit diagrams before (GCSE electronics at school, made a random number selector with an LED display and all hell yea! plus soldered some Xbox stuff and other odd little projects like a 9v battery to USB charger) but this is my first step into the audio foray.

So I thought well CMoy but during research I found about the Mini³ and it looks perfect. Parts from amb.org run to £24 delivered and I can get the rest from maplins for like £10-£15 so it fits nicely in with my budget.

But the questions are:

1) Does it sound decent enough?

2) will it be of any use with JH13's? clearly there is alot better but as a starter amp is it a decent one to start with? SoupRKnowva has given me this advice:
Quote:

if you're planning on using it exclusively with jh13's you can even set the gain to unity, or maybe even negative gain to work best with the low impedance/high sensitivity of the jh13's

which sounds good..but means little..ah and an update:
Quote:

the gain is how many times the input voltage gets multiplied, typical headphone amps vary anywhere from 3-15dB. but since the jh-13s are so sensitive, they can easily run off the voltage provided by the source, so a gain of 0, unity gain, is more than enough for them, and actually like -3 or -5 might actually be better, allowing you to use more of the volume control.

so some research needed on that

3) which Opamp to use? I assume the high performance edition is what to go for:
Quote:

The high performance edition utilizes an Analog Devices AD8397 dual opamp for the left and right channels, and a Texas Instruments/Burr-Brown OPA690 opamp for the ground channel. These opamps have very high output current capability (~190-250mA), and could drive low and high impedance headphones with authority.

4) this may seem extremely dumb but the wall charger..specs:
Quote:

412-112053 (for 120VAC 60Hz USA, rated 12V/500mA, actual ~17VDC unloaded)

UK voltage is 240V...will this present a problem?

 

[ShinyFalcon]

1)

2) 2x with my Mini³ and Triple-Fi was still pretty loud, no room for volume travel before hitting volume imbalance...
3) Yes, if you want great sound, go for the high performance, otherwise go for the extended-life if extra battery life is needed
4) If it doesn't say 240VAC input specifically, it probably won't work.

 

[simwells]

I've just built mine, and love it (also in the UK)

4. If you look at the partlist, Farnell 1217103 is recomended for UK usage, but pretty much any will work providing it outputs 15-24VDC is 300mA+ and is a 2.5mm barrel plug.

 

[timmyGCSE]

Quote:

Originally Posted by ShinyFalcon /img/forum/go_quote.gif 1) 2) 2x with my Mini³ and Triple-Fi was still pretty loud, no room for volume travel before hitting volume imbalance... 3) Yes, if you want great sound, go for the high performance, otherwise go for the extended-life if extra battery life is needed 4) If it doesn't say 240VAC input specifically, it probably won't work.

Quote:

Originally Posted by simwells /img/forum/go_quote.gif I've just built mine, and love it (also in the UK) 4. If you look at the partlist, Farnell 1217103 is recomended for UK usage, but pretty much any will work providing it outputs 15-24VDC is 300mA+ and is a 2.5mm barrel plug.

cheers guys ^_^ simwells, where did you source the parts from and how much did you spend in total approx?

 

[simwells]

Quote:

Originally Posted by timmyGCSE /img/forum/go_quote.gif cheers guys ^_^ simwells, where did you source the parts from and how much did you spend in total approx?

I used AMB for all the parts I could from there, then Farnell for pretty much everything else (got the knob second hand from here and the already had the battery.) I think in the end it was roughly £50, the wallwart and casing are a fair chunk of the parts other than the AMb ones.

 

[Beefy]

Quote:

Originally Posted by ShinyFalcon /img/forum/go_quote.gif 3) Yes, if you want great sound, go for the high performance, otherwise go for the extended-life if extra battery life is needed

I thought that the key point of the 'high performance' version was higher current capacity. Not really an issue for IEMs I wouldn't think.

And from memory, the OPAMP used for the extended battery version actually measures better.

 

[timmyGCSE]

Quote:

Originally Posted by simwells /img/forum/go_quote.gif I used AMB for all the parts I could from there, then Farnell for pretty much everything else (got the knob second hand from here and the already had the battery.) I think in the end it was roughly £50, the wallwart and casing are a fair chunk of the parts other than the AMb ones.

yea the trouble is farnells want me to order in bulk of 10 for alot of the stuff

gonna look in maplins

Quote:

Originally Posted by Beefy /img/forum/go_quote.gif I thought that the key point of the 'high performance' version was higher current capacity. Not really an issue for IEMs I wouldn't think. And from memory, the OPAMP used for the extended battery version actually measures better.

so you say go for the extended life?

 

[Beefy]

Quote:

Originally Posted by timmyGCSE /img/forum/go_quote.gif so you say go for the extended life?

I haven't heard either version...... but if I was building one for IEMs, it would be the extended life.

 

[Pars]

You could just order a kit from Glass Jar Audio...
AMB lab's Mini Cubed Portable Amplifier [international]

Has everything except the wallwart.

 

[timmyGCSE]

Quote:

Originally Posted by Pars /img/forum/go_quote.gif You could just order a kit from Glass Jar Audio... AMB lab's Mini Cubed Portable Amplifier [international] Has everything except the wallwart.

looks good but its £52. I've got all the components bar the box (which I was gonna make outta wood coz I'm cool like that) the wallmart..and..one DAMN resistor!!! the 6R2 (need two of them)! everything from rapid electronics but they have none, maplins don't either. Farnell do but you have to order a minimum of £20 worth of stuff

I've got it all down to about £34 so What that pees me off that I'm being held up by one damn little resistor!

 

[simwells]

Quote:

Originally Posted by timmyGCSE /img/forum/go_quote.gif looks good but its £52. I've got all the components bar the box (which I was gonna make outta wood coz I'm cool like that) the wallmart..and..one DAMN resistor!!! the 6R2 (need two of them)! everything from rapid electronics but they have none, maplins don't either. Farnell do but you have to order a minimum of £20 worth of stuff I've got it all down to about £34 so What that pees me off that I'm being held up by one damn little resistor!

PM me your address and I'll send you a pair, (they'll be 6R8's but that's fine and Ti mentions using them anyway)

 

[timmyGCSE]

Quote:

Originally Posted by simwells /img/forum/go_quote.gif PM me your address and I'll send you a pair, (they'll be 6R8's but that's fine and Ti mentions using them anyway)

oh rly? if I can use 6R8's then thats no problem at all

I can find them easily but cheers very much for the offer

 

[simwells]

Quote:

Originally Posted by timmyGCSE /img/forum/go_quote.gif oh rly? if I can use 6R8's then thats no problem at all I can find them easily but cheers very much for the offer

Yeah if you look on the partslist the Farnell code for the component is listed as being 6R8 and they work fine in mine!

 

[amb]

High performance edition performs better into a low impedance load, and IEMs are usually low impedance.

 

[Beefy]

Does that stand true even when the voltage swing required due to the high sensitivity is very low? And thus very little current draw?