Poll

I would like...

Stand-alone amp
14 (42.4%)
DAC and Amp
6 (18.2%)
The whole bang shoot, USB, crossfeed etc
6 (18.2%)
A mistress for christmas
7 (21.2%)

Total Members Voted: 33

Author Topic: Forum DIY Headphone amp kit  (Read 38248 times)

Offline GearSlave

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Re: Forum DIY Headphone amp kit
« Reply #30 on: August 21, 2010, 02:00:25 AM »
Geesh guys, you giving me way too much credit! Trust me...

The PCB and parts will be around R600-R700. This is assuming the PCBs will be around R150 a pop to have made. We still need to get some more TPA6120s. This can be done either as samples or as an order from Digikey. To get them as samples, we need to ahve a few of the takers here order them, as I can't order anymore.

I'll pop past Mantech during the week to see what the knobs look like. Do you have a part number or link on the Mantech Website Stu?

I'm suggesting we use one of those AP enclosures. It's similar to the one I posted here a few days ago and the same as I used on the Gerdac. This should come in at around R150.

Any suggestions on where to get ALPS Blue Velvet pots locally? Or Anywhere for that matter?

So, if I had to suggest a budget, it would be around R1000 mark. I'm assuming that many people would want an assembled unit; I'll give some thought as to how much to charge to do the assembly, if required of course.
Resistance is not futile; it is voltage divided by current (R=V/I)

Offline ludo

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Re: Forum DIY Headphone amp kit
« Reply #31 on: August 21, 2010, 03:17:22 AM »
Like these ones Stu?

http://www.mantech.co.za/ProductInfo.aspx?Item=S87315A

I've got a few 18mm dia and 10 x 24mm dia like those here, but the colour is not quite the same. Wanted the larger (35mm?) ones but they've never had stock AFAIK. 24 was the biggest one last time, earlier this year. These are for splined shafts, not round. Edge is a bit sharper than on that pic.

@Gert
RS keep those Alps pots. Only with round shafts AFAIK. They're carbon pots with 15k cw-ccw life expectancy. I never understood the fuss made about them. If the case is very light/small the grease damping on the shaft could actually be a problem. Gang error is OK though. Alps Black Beauty was the conductive plastic job, but I think those would have to be NOS now. RS also keep Sfernice cermet P11 (ie not PA11, I don't like conductive plastic) Those are pots... if you can find a log dual. 100k wipes in both directions at 1Watt dissipation minimum. They used to grade them for 1million cw-ccw. PITA if you ever need to give them Servisol, but possible. If one doesn't pinch pennies and combines 4 sections of linear modules and throw the extra 3 shafts away, you really get something else. Ultimate taper you might say. Low level control at last, without silicon, but the input impedance shifts 10:1. One can add a resistor to sort out most  of the end-stop irregularity on the extra sections though. They do have log PA11 duals, if you must :). All have funny different names now that Sfernice and pretty much everyone else is part of Vishay. But look for the square white ones in the cermet section. Only round shafts again. Dang! The man with the lathe is your best bud. Should be eh? ;D

Much obliged if you could give a part number for the AP case. I went there after I was at Mantech and they had this rack of horrible dusty things. "Sorry but if it's not there we don't have, really... " I'd like some of those pretty ones. The NuTech ones at RS are just extruded, but if you don't need a lid and things can just slide in its good value. Black Aluminium with nice front and back up to quite long ones.

http://za.rs-online.com/web/search/searchBrowseAction.html?method=browseSubRange&Ne=4294954291&N=4294930949&productNum=1853186

Cant use them for my effort 'cos it needs big mother heatsink. No usable flat surface inside...

If it 's going vrot, put it on the buffet ! - Fats

Offline GearSlave

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Re: Forum DIY Headphone amp kit
« Reply #32 on: August 21, 2010, 07:08:48 AM »
AP is not the most organised place, but when I go there I make a point to spend at least half an hour there to go through all the nooks and crannies. You'd be surprised with the things I found. Anyway, I've posted many pics of the enclosures here, but will pull out the camera a little later and get some more specific shots. But they are those dusty ones that were pre-cut, you just have to go through them to find the nice ones.

I also like those black ally enclosures you linked above. I little more pricey, but they do look classy. There's also the Hammond ones

http://za.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=4580752#header that I quite like.

Why is it that you don't like the plastic film ALPS pots? They are supposed to be the real fancy ones?
Resistance is not futile; it is voltage divided by current (R=V/I)

Offline BWS

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Re: Forum DIY Headphone amp kit
« Reply #33 on: August 21, 2010, 08:20:40 AM »
Poll updated, please cast your vote

Whoever originally coined the word 'Lisp' and put an 'S' in it's spelling, is a Douchebag !!

Offline ludo

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Re: Forum DIY Headphone amp kit
« Reply #34 on: August 21, 2010, 08:45:14 AM »
I don't mind dirt. Will go check again and be more insistent. Thanks.

Why is it that you don't like the plastic film ALPS pots? They are supposed to be the real fancy ones?

Never had an Alps one. Just P&G faders. There might be some prejudice in it, but hey, when one goes by ear anything is allowed. Russ Andrews started it. Corrupted me many years ago by printing in his catalogue that the conductive plastic ones sound like they are "mumbling into their beards" compared to cermet. Tried it and blow me down, I thought the man was right. One can make some bird-brained theory about why, but the only thing you will see from a spec sheet is that conductive plastic has much higher tempco than carbon, which is higher than cermet in turn. Cermet being like a metal film resistor at 50-100ppm or so. There's really not much power on a pot so it should hardly matter at all. Especially as a 100mm fader is physically very large & well ventilated. It just sits at room temp. Never bothered with anything below 50ppm resistor-wise myself because it gets expensive then. But apparently if one does instrumentation this type of thing can form part of the error budget. Few resistor manufacturers tell one the thermal resistance of their parts, unlike with semiconductors. Should be as important as tempco. Maybe 1/2 Watt carbon is as good as 1/4W metal film.

P&G faders will mean a lot if you mix on them. Even at the price (~1k a pop for the mono cheapies IIRC). They have this neat mirror finish that doesn't give one's tweaks away by scratchy noises. But we're not mixing.

For subjective things, one can roll your own. No need to believe what you read on the net, or what I read in a catalog, obviously. There are no rules then and carbon composition even makes a comeback for those smooth tones in phase splitters of all places. I'm convinced Alps Blue Velvet sells because it looks distinctive and the name sounds so cool. Nothing like an oxymoron (conductive plastic) in a marketing stunt, even if it is really carbon on the spec sheet.

But the Sfernice stuff is about the same price as the carbon Alps pots, and available. So one can try it and see if it sits. It will last longer. Which I obsess about more than I should, I guess.

Don't mind me. Just dishing ideas out. I'd actually like one of your kits if I can afford it. Can mos mar fiddle with it if I like.

If it 's going vrot, put it on the buffet ! - Fats

Offline GearSlave

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Re: Forum DIY Headphone amp kit
« Reply #35 on: August 21, 2010, 08:54:21 AM »
For subjective things, one can roll your own. No need to believe what you read on the net, or what I read in a catalog, obviously. There are no rules then and carbon composition even makes a comeback for those smooth tones in phase splitters of all places. I'm convinced Alps Blue Velvet sells because it looks distinctive and the name sounds so cool. Nothing like an oxymoron (conductive plastic) in a marketing stunt, even if it is really carbon on the spec sheet.

In hunting around, it would appear the ALPS Blue Velvet only exists in Audiophile minds.

Nothing about it on ALPS website
http://www.alps.com/WebObjects/catalog.woa/E/HTML/Potentiometer/RotaryPotentiometers/RK271/RK271_list.html

But mentioned here
http://www.partsconnexion.com/product7387.html

It looks suspiciously similar.

And here
http://za.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=2369604
It's classed as a carbon pot.

So, I'm really at a loss if I've got the right thing here or not...

But the Sfernice stuff is about the same price as the carbon Alps pots, and available. So one can try it and see if it sits. It will last longer. Which I obsess about more than I should, I guess.

Cool, I'll look for it.

Don't mind me. Just dishing ideas out. I'd actually like one of your kits if I can afford it. Can mos mar fiddle with it if I like.

Please, keep em coming!
Resistance is not futile; it is voltage divided by current (R=V/I)

Offline xumbug

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Re: Forum DIY Headphone amp kit
« Reply #36 on: August 21, 2010, 10:01:54 AM »
Hey Ludo, thats the one's. They are of good quality and feel strong. Look much better in the flesh ;)
SDA Acoustics loudspeakers, Audio Research Ref 3 Pre amp and Ref 210 power amps, Bel Canto VB3.5 Dac, Pathos Endorphin cd player, squeeze box touch.

Offline xumbug

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Re: Forum DIY Headphone amp kit
« Reply #37 on: August 21, 2010, 10:06:54 AM »
Lets try and keep the enclosure classy looking, if that is ok. Lets face it, this thing will be sitting with the rest of our gear. If the basic unit is going to cost at least a grand, i dont mind paying a few hundred more for something i can be proud of :)
« Last Edit: August 21, 2010, 10:09:32 AM by xumbug »
SDA Acoustics loudspeakers, Audio Research Ref 3 Pre amp and Ref 210 power amps, Bel Canto VB3.5 Dac, Pathos Endorphin cd player, squeeze box touch.

Offline BWS

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Re: Forum DIY Headphone amp kit
« Reply #38 on: August 21, 2010, 10:20:15 AM »
Lets try and keep the enclosure classy looking, if that is ok. Lets face it, this thing will be sitting with the rest of our gear. If the basic unit is going to cost at least a grand, i dont mind paying a few hundred more for something i can be proud of :)

+1
Whoever originally coined the word 'Lisp' and put an 'S' in it's spelling, is a Douchebag !!

Offline Cure

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Re: Forum DIY Headphone amp kit
« Reply #39 on: August 21, 2010, 10:56:50 AM »
I agree with xumbug.

Gert and Ludo teaming up...this should be exciting.

@gert
What would be the input connection on the amp? 3.5, rca, usb?

6120's non stock in digikey. Can't we source them somewhere else.


Offline BWS

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Re: Forum DIY Headphone amp kit
« Reply #40 on: August 21, 2010, 11:35:16 AM »
You can order samples here for free http://focus.ti.com/docs/prod/folders/print/tpa6120a2.html

Unfortunately, like Gert I cant order samples for a while yet and have mailed him the five i did have
« Last Edit: August 21, 2010, 11:37:22 AM by Skinny »
Whoever originally coined the word 'Lisp' and put an 'S' in it's spelling, is a Douchebag !!

Offline Cure

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Re: Forum DIY Headphone amp kit
« Reply #41 on: August 21, 2010, 01:03:12 PM »
^Thanks for link.

Btw, How many 6120s do we need?

Why don't we make an interest checklist so we have an idea how many are we?




Offline LAV

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Re: Forum DIY Headphone amp kit
« Reply #42 on: August 21, 2010, 02:36:29 PM »
Maybe the "amp only" option is the best one, although the "DAC in the (same) box" idea is  tempting. Not everyone is necessarily going to feed the beastie with ones and zeros. If it is a combo unit, it would probably be good to have a separate analogue input too...

I'd be happy to go with either option, i.e. amp only or DAC + amp.
Vaal Triangle (Southern Gauteng)

Offline MorneDJ

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Re: Forum DIY Headphone amp kit
« Reply #43 on: August 22, 2010, 01:09:03 PM »
I registered to get some samples. While I am at it, are there any other "samples" I can try to get. I am actually interested in some opamps, as I plan on doing preamp at some time as well as active crossover. Any ideas and suggestions ?

Regards,

Morné
Do not meddle in the affairs of dragons, as you are crunchy and taste good with ketchup ...

Offline Apocalypse Boy

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Re: Forum DIY Headphone amp kit
« Reply #44 on: August 22, 2010, 01:35:43 PM »