[durkk]

Howdy ho folks. So i am looking for a fun (beginners) kit. I don't have any experience doing this type of stuff, except for soldering the occasional XLR and one time a FET buffer, granted it was just a view steps and well documented. And that's kind of what I am looking for in this project too.
 
Now I know many people recommend using vintage receivers, so I was wondering if any diy amp-receiver kit´s might be cool. Although it might be harder to make it suitable for headphones?
 
The main goal: something better than a Schiit Magni, Objective 2 etc. >200$ budget (if I am going to spend 200$ on a diy project, it better be better than just buying an entry level amp). No tubes. Want to power it with a adapter.
 
Design:
I am a sound designer and might actually want to place the thing in a 19inch rack together with some other hardware. With the amount of space, I would like to add a crossfeed. If this makes any difference in the options of parts please do suggest some things - perhaps there are good kits out there with crossfeed built in?
 
This being my first project however, I am also fine with making a simple casing and don't make a crossfeed at all. 
 
I hope this made any sense, and sincerely hope someone can help me out, shed some light on this.
 
I am located in the Netherlands btw, so conrad and EU dealers etc prefered for parts.

 

[nikongod]

You might be able to build a low-power gainclone (using one of the chips rated for 12-25w) in a 19" enclosure. 
 
There will be room for crossfeed. 
 
I doubt this is the best solution, but perfect is the enemy of good. 

 

[durkk]

  You might be able to build a low-power gainclone (using one of the chips rated for 12-25w) in a 19" enclosure. 
 
There will be room for crossfeed. 
 
I doubt this is the best solution, but perfect is the enemy of good. 

Thanks!
 
I was just looking at Gianclone kit's. Do you happen to know of a headphone version kit?
 
What would you say am I sacrificing in terms audio quality when going the 19inch/crossfeed route? I am also just fine with starting out with a gianclone in a little higher enclosure. 

 

[durkk]

anyone paired this with the LCD 2? http://www.headfonia.com/hifimediy-tk2050-amplifier/

 

[nikongod]

The catch with orthos is that they are not like other headphones. 
For a headphone amp designed to be a headphone amp, sell the LCD2 and get HD800. 
For headphones that need to be run off of a speaker amp, get a speaker amp. 
 
That being said. 
http://www.head-fi.org/t/654371/eddie-current-diy-amplifier-monolith
This. 
 
I am biased against Class-D amps, for so many reasons. 
You dont need 100w, do you? You barely need 1/8w (which is a lot for a headphone amp...) So why deal with the impossibilities of the output filter? 
 
Regarding 19" rack mount equipment, I'm not personally sure what you give up when you use 19" gear, but none of my local speaker buddies would touch anything in a 19" rack with a 20ft pole. I'm not sure why, some of the nicest (digital) gear that can be bought only comes in 19" mountable chassis and everything they have ever heard went through about a zilion 19" rack mount boxes to do different things... 
Ignoring the constraints on height, and possibly limitations on ventilation there is no real downside. 

 

[00940]

You might try this one: http://www.audiophonics.fr/audiophonics-apd86-mkii-amplificateur-stereo-lm3886-2x68w-p-5772.html 32€
Paired with a lowish voltage transformer : http://www.audiophonics.fr/transformateur-torique-60va-2x22v-ecran-electrostatique-p-4751.html 29€
And maybe regulate the voltage to keep noise down: http://www.audiophonics.fr/module-alimentation-lineaire-regule-double-lt1083-20v-75a-p-8426.html 27€
A 19"/2U rack: http://www.audiophonics.fr/hifi-2000-boitier-300mm-facade-4mm-silver-p-1044.html 44€
You need some heatsinking too, this one would fit nicely at the back of your rack: http://www.audiophonics.fr/radiateur-dissipateur-thermique-anodise-noir-200x80x40-p-7239.html 19€
And a decent pot: http://www.audiophonics.fr/potentiometre-alps-stereo-rk27-haute-qualite-50kohm-p-2217.html 10€
 
So, 161€. As usual the amplifier itself isn't the major cost factor.
 
You'll still need rca, iec jack, screws, etc, etc. You should be around 200€ before shipping.
 
Btw, in Europe, Reichelt.de is very cheap compared to most other shops.
 
Audiosector and chipamp are classical websites to buy gainclone kits on the other side of the ocean.

 

[durkk]

Thanks alot guys!Got lot's of investigating to do! Hefty projects I'm guessing the 19inch rack will introduce lot's of 'outside the kit' thinking, something I am not very confident about.
 
Any recommendations on a crossfeed kit that integrates nicely?
 
The goal is to get a nice amp for the LCD 2, since I mainly bought them for the bass response. HD800's would drastically decrease the need of a crossfeed, with it's superior imaging tho. But like I said, the LCD's are chosen purposefully. I also have a nice pair of Focal nearfields which are very good at positioning things in the mix. Alot of my end users will be using cans tho.
 
Thanks for thinking with me on the EU parts 00940. Will be looking in to how I would go about assembling that list
 
Do you guys think a low budget DIY kit is still better than an entry amp like the Magni/O2? 
 
Sorry for all the n00b questions

 

[00940]

Sorry, I did miss the part where you wanted an adapter rather than building a complete supply. It makes things a bit more difficult: external power supplies are usually single voltage, so you need either a bridged amp (which means recabling the lcd2 to balanced cables) or an amp with an output cap made for a single supply, which is very uncommon as kit.
 
I went back to the LCD2 requirements. For 120dB peaks, you need 1W. Into 60R, that means 8Vrms (22.6Vp-p), 190ma peak. Honestly, that's a lot more power than probably needed. The O2 is nearly there and it would be sufficient most of the time (always ?). If you're ok with 111db peaks, the O2 will do it quite easily. I don't think there are any full-kits-using-a-single-supply-having-more-power-than-the-O2 which could be build for less than 200€, taking into account the cost of a 19" rack.
 
Except for those tripath amps... The Hifimediy T1-M would work. I'd still put a 10R/15W resistor in // with the headphones to properly load the amp. They have a 24v/2.5A power supply for it that'd be ok. That means a new cable for you cans btw.

 

[durkk]

I went back to the LCD2 requirements. For 120dB peaks, you need 1W. Into 60R, that means 8Vrms (22.6Vp-p), 190ma peak. Honestly, that's a lot more power than probably needed. The O2 is nearly there and it would be sufficient most of the time (always ?). If you're ok with 111db peaks, the O2 will do it quite easily. I don't think there are any full-kits-using-a-single-supply-having-more-power-than-the-O2 which could be build for less than 200€, taking into account the cost of a 19" rack.

Thanks alot! Would it be possible to hack the AC input to the back of a 19inch rack and chuck the whole design to the left of the rack (copying NwAvguy design except extending it to 19inch length)?
 
Otherwise I'll just buy the mayflower design with the ac on the back.

 

[00940]

You mean creating a new PCB for it ?

 

[DingoSmuggler]

  ...but none of my local speaker buddies would touch anything in a 19" rack with a 20ft pole. I'm not sure why...

19" is the quarter wavelength of 176Hz, so resonates at this frequency.
Just google 176Hz to find out why 19" gear sounds like poo.

 

[durkk]

  19" is the quarter wavelength of 176Hz, so resonates at this frequency.
Just google 176Hz to find out why 19" gear sounds like poo.

Yes, I gathered this is Audiowoo, thanks for the trolling confirmation.
 
00940: Yeah, although formfactor might be something I'll worry about later on. Perhaps I'll just start with a more advanced crossfeed in half rack unit and see if I can pull that off first

 

[00940]

If you're redrawing the O2 pcb, you can as well keep the overall design but increase voltage and current capacities (adding a njm4556 or two into the mix). Or add options such as balanced inputs (useful in pro environments).
 
Problem is that the pcb design is an integral part of the design and getting new pcb done will add cost. It might interest me to have a look at it though.

 

[durkk]

  If you're redrawing the O2 pcb, you can as well keep the overall design but increase voltage and current capacities (adding a njm4556 or two into the mix). Or add options such as balanced inputs (useful in pro environments).
 
Problem is that the pcb design is an integral part of the design and getting new pcb done will add cost. It might interest me to have a look at it though.

Balanced in would be pretty cool indeed!
 
You dare making a ballpark figure? I could perhaps pick up a 1u defunkt server rack for like a tenner. Then make a front plate via plate express. 

 

[00940]

Here is an idea for you:
 
- Get that 1U rack.
- Get a  10-0-10VAC/40Va adapter. They're plentiful on ebay, they were used as HP printer supplies, search for "17222b". Here is one for cheap for example. They can be used as 20VAC/2A supply.
- With that adapter, make a dual +/-16Vdc supply, like in the O2. It will be powerful enough to not only supply your headphones amplifier but also other small things you might want to put in the rack. That could be made single sided and easily etched.
- Then, get a few 5*5cm pcb made. One for balanced to unbalanced conversion, one for gain and volume control, one per channel for current buffering, etc. Once panelized on a 10x10cm board, they should be quite cheap from a Chinese pcb fab.
 
If you're not in a hurry, I can provide you with the files for the pcb in the newt weeks.