Beefy's DIY headphone amp

[Beefy]

Hi all!

I’m currently in the process of building a DIY headphone amp, and Marcus has given me the nod to post a mini-worklog on this fine forum. I am building an M Cubed from AMB Audio http://www.amb.org/audio/mmm/ which will be powered by a separately housed Sigma 11 power supply http://www.amb.org/audio/sigma11/. The goal with this project is to build something that is at LEAST as good as my Arietta...... but hopefully end up with something that is considerably more powerful, with a few little bonus features. Specifically, I intend to set up the amp with a continuously variable gain to be suitable for everything from super sensitive canalphones to the hungriest fullsize phones (gain will range from 2-12 and be selectable by a pot on the front panel). Also, I am buying a number of different opamp combos to suit different headphones (smoother Burr-Brown opamps for energetic/detailed phones like the Alessandro range, and more ‘detailed’ Analogue devices opamps for smoother phones like Audio Technica).

My only previous audio DIY effort (recabling some MS-1’s) was almost a spectacular failure. But it was a mechanical failure, because the diameter of the cable was too big for the connectors I bought. I’ve had lots of experience in the past with electronics kits from Dick Smith and Jaycar so I’m supremely optimistic that it will all work out. But this is the first project where I’ve actually bought all the individual components myself. At the very least, it will be entertaining for all of you if I crash and burn……

First things first, what this thread is about. I am NOT intending to give a tutorial on how to build your own amp and I will NOT be giving out my BOM for you to re-create my work. This post is to share my experience, and should in no way shape or form take any business away from Headphonic.

Anyway, onto the nitty gritty. The parts I bought were all solid, premium parts like Vishay Dale resistors and Nichicon high reliability caps – but not super expensive boutique stuff like Black Gates. They’re just not required for good performance from this amp, because it is entirely DC coupled with no capacitors in the signal path. It was VERY difficult to source parts locally, because places like Jaycar and Altronics generally stock low grade crud, and high end suppliers like RS and Farnell have terrible prices and stock levels in their Australian stores. Thus almost all my stuff was bought overseas from AMB, Mouser and Digikey. I got my Mouser delivery yesterday, AMB attempted delivery this morning, and Digikey should come tomorrow or Thursday. I’ll start the worklog with a photo of all the parts together on my desk.

Overseas shipping cost me a fortune. More than one quarter of the total money I spent was shipping, which was a lot more than I expected. In fact, everything ended up costing a lot more than I expected. I came to the conclusion very rapidly that if you’re looking to DIY to get a really good product cheap, then you’re doing the wrong thing. At best, the time spent is certainly more than any dollar savings will be…… so if you’re not in it for the ‘journey’ then don’t bother.

So I think that is all for today. If anybody else has some DIY stories, I’d love to read them!

Cheers,
Beefy

[dc]

Overseas shipping cost me a fortune. More than one quarter of the total money I spent was shipping, which was a lot more than I expected. In fact, everything ended up costing a lot more than I expected. I came to the conclusion very rapidly that if you’re looking to DIY to get a really good product cheap, then you’re doing the wrong thing. At best, the time spent is certainly more than any dollar savings will be…… so if you’re not in it for the ‘journey’ then don’t bother.

Truer words have never been said. I completely agree.

DIY may seem like a way to get a great product at a low price, but unless you

1. know what you're doing
2. have all the necessary tools and equipment
3. have parts available locally

then it will end up costing you the same or MORE than an equivalent commercial product. especially in the time wasted trying to make things work.

Good luck on the project though Beefy, look forward to you sharing with us your journey. I've thought about the M3 more than a few times and to be honest I can't see myself completing it given the nature of the beast.

[Beefy]

then it will end up costing you the same or MORE than an equivalent commercial product. especially in the time wasted trying to make things work.

If I do everything completely right, I should theoretically end up with something far superior to the Cantate in terms of driving power (and possibly lower noise floor due to the external power supply) for just a smidge less money, but at a cost of many tens of hours. Whether this is true or not remains to be seen, and just by saying it I've almost certainly set myself up for a fall.......

But I have decided that everything I have spent is money that I am willing to lose 100%. Indeed, I don't think anybody should do DIY if they aren't willing to lose it all.

I've thought about the M3 more than a few times and to be honest I can't see myself completing it given the nature of the beast.

Well the project that originally caught my eye was the Beta 22. It was initially attractive because it can be bought as a complete kit from certain suppliers. But the level of complexity is FAR beyond what I could manage at this early stage, and the M3 is quite easy by comparison. The final cost of the B22 was also at least double that of the M3 - not good for a first project!

In all honesty, I think that the casework will cause me the most grief. But with any luck, I can prepare the cut-out diagrams and have the workshop guys in my faculty do it for the cost of a six pack of beer......

[dc]

yes, case work is the biggest deterrent for me.

stuffing boards and reading some measurements is no issue

it's when things go wrong that scares me most.

I know the supplier you're talking about, they also offer M3 kits, what made you not go with those?

[Beefy]

I know the supplier you're talking about, they also offer M3 kits, what made you not go with those?

Mini3 kits I believe. I couldn't find anybody who made M3 kits.

[Beefy]

The cases arrived at work today, and the AMB order with the circuit boards, volume/gain pots, JFETs, MOSFETs, MOSFET heatsinks and 1µF caps is waiting for my signature at the post office. I'm excited!

Still no sign of the Digikey order though, with the all-important OPAMPs and power rectifier diodes. Might have to chase it up tonight.......

[EDIT] Spoke too soon - Digikey just arrived by internal mail. Hurrah!

[Calroth]

Niiiice.

Agree with the sentiments on DIY. To paraphrase that ad, listening to something you made yourself and loving it: priceless.

With your variable gain, I'd find a way to test-drive that before you have to solder that pot down (if you're re-using the bass boost circuit). I think a gain of 12 will be overkill for most headphones you'd care to try, for most sources you'd care to hook up to. If it was me, I'd find a gain that I could live with for all my headphones, and lock it in--or at worst, socket the relevant resistors. From what I understand of the variable gain, you're extending the "inner loop" of the voltage amp stage by a long way (out to the front of the case!) and this can cause instability, but in practice it probably won't.

[Beefy]

With your variable gain....... and this can cause instability, but in practice it probably won't.

Thanks for the support Calroth! I checked the sanity of the gain with AMB himself. No problems

*

Anyway, here's a photo of all the parts laid out in baggies.



And here's the result of a couple of hours *slow* work....... the S11 board essentially complete, except for MOSFETs and heatsinks. Soldering to the ground plane of this thing is a nightmare, because it saps away a LOT of heat.

[dc]

looks great keep the photos coming.

[Calroth]

Nice. nice nice nice nice nice.

You've probably read this, but you really gotta be careful with the σ11... you're working with AC line voltage, which can be a lethal shock hazard. It scares the hell out of me, which is why I prefer a TREAD instead. But then, there's no voodoo or magic involved with working with the mains, if you follow good safety practices then you'll be fine.

Hm, I don't see the toroidal in that pic?

[dc]

yes, bring on the trannies!

[Beefy]

you're working with AC line voltage, which can be a lethal shock hazard

My dad was a sparky in his young days. I've rewired half my house. [EDIT] Mind you, I have had at least three 240V, 10A shocks in my life - all unrelated to electronics though.....

Hm, I don't see the toroidal in that pic?

Still need to grab it from Altronics.

yes, bring on the trannies!

You can have the trannies all to yourself......

[Dave_Ease]

Nice work. The M3 is high on my "To Build List".

For my stories: I've just got a MilletMAX working quite nicely. It still needs some casework but I'm enjoying it a little too much without finishing it to really care at the moment. It was a bit of a pain, I had two of the output BJT's the wrong way around, which toasted them and some of the smaller chips. The output ones were simply replaced with some I had on hand, the smaller ones needed to be shipped in, which took a while.

In the pipe are a few Mini3's, a Bijou, a DAC-301 and several JISBOS that will turn into a balanced buffer for the DAC-301 (to feed a pair of SR-80's that will become balanced). Much further down the pipeline are several b22's (I rather ambitiously bought a number of the backplane boards...let me know if/when you're game to attempt the b22, perhaps we can split some shipping...). Not quite headphone related are a pair of balanced F4's...they would give me a good excuse to chase a pair of k1000's though. I've got even more stuff brewing but they're the biggies that'll be finished sooner.

You probably don't really want to know this now but the hush-hush vendor does do kits for the M3 (as well as a number of other amps, just ask: he/she/they are very helpful).

I love DIY, all the trouble you go to to get the amp going makes the final listening so much sweeter.

Josh

[Beefy]

For my stories:

Wow, lots of goodies happening there!

You probably don't really want to know this now but the hush-hush vendor does do kits for the M3

Yeah, I know that now. Apparently they update one of their sites much more frequently than their storefront. Could have saved myself a fair bit of cash (though not heaps, unless they do a S11 as well?), and got Muse caps to boot. But I'm fairly happy to console myself in the fact that it was good experience to pick my own parts.

[dc]

wow Josh! that's some seriously cool stuff you've got in the works

just wish i had the skill and/or patience to build my own stuff

alas... do you DIY for others?

(don't quite understand your forum nick)