"The Wire" Ultra-High Performance Headphone Amplifier - PCB's

I have a noob question. I've tried searching but I can't seem to find satisfactory answers. What is the difference between the SE and BAL boards? Does it depend on the other components in the system?
For reference I recently bought a pair of HD598s primarily for PC listening (music, movies, games). I am looking for an amp I can build that will be able to easily drive these headphones and possibly any upgrades in the future.
For inputs I want RCA for now with a USB DAC in the future (hopefully OP's. ETA?). Is it possible to wire the RCA connections in parallel with the DAC output without some sort of isolation between them?
Thanks for any help.
 

opc

Member
Joined 2004
Paid Member
Has anyone tried using Twisted Pear Audio Buffalo/Legato IV with the BAL-BAL Wire?

The Legato has a common mode DC bias between the output and ground. I believe it’s about 6 VDC. I do not have electronic engineer background needed to analyze the circuits to know if the Wire can properly accept the balanced output from Legato (either with the ground connected or not connected).

Thoughts?

The above arrangement should be fine, but depending on your setup, the DC may be carried through to the output of the headphone amp. It will be common mode, however, so any headphones attached across the differential outputs will be fine. Give it a try, and measure the DC offset on the output of the BAL-BAL amp. If it's less than a few mV, then you should be safe to plug in headphones. I definitely wouldn't hot-swap any cables, however, as you might get some significant clicks and pops.

I have a noob question. I've tried searching but I can't seem to find satisfactory answers. What is the difference between the SE and BAL boards? Does it depend on the other components in the system?
For reference I recently bought a pair of HD598s primarily for PC listening (music, movies, games). I am looking for an amp I can build that will be able to easily drive these headphones and possibly any upgrades in the future.
For inputs I want RCA for now with a USB DAC in the future (hopefully OP's. ETA?). Is it possible to wire the RCA connections in parallel with the DAC output without some sort of isolation between them?
Thanks for any help.

The difference between the BAL-BAL and SE-SE is the input and output arrangement of the amp itself. The SE-SE can only be used with a single ended (RCA) input and only supports single ended output with a ground reference.

The BAL-BAL can be used with either SE (single ended like RCA) or BAL (Balanced or differential, like XLR) input, although it works best with BAL.

The BAL amp also has a differential output, meaning there is no ground reference, and the output signal is a differential voltage across two output terminals, each drive by a buffer. You can take just one phase of the output and reference it to GND to get a single ended output, but again, it works a lot better with the differential output.

Note that you will probably have to re-wire your headphones for proper differential operation, unless you bought a pair specifically wired for it. Headphones wired up for proper differential operation have some significant benefits in that crosstalk is improved because each channel has a fully dedicated return path, and are not required to share a common ground.

In a nutshell, the BAL-BAL amp will provide the best possible performance providing you have a balanced source for the input, and headphones wired up for differential output. You get better crosstalk, twice the output voltage swing capability, and lower second harmonic distortion.

Based on your requirements, though, the SE-SE sounds like it would be a better fit.

As for your last question about wiring the DAC outputs in parallel, I'm not really entirely clear on what you're asking. If you just want to run the DAC RCA outputs to the headphone amp and some other amp, then you should be fine to just wire them in parallel as long as the DAC can drive the combined parallel load. There shouldn't be a need for isolation unless you end up with a ground loop.

Can some one give me some comparison between Wire and some other respected amps like O2, M3 ... or other commercial amps? And just want to know how good the Wire is.

I'll leave this to others for comment, as it's not really a good idea to self review :)

I can say that it measures better than the aforementioned amplifiers, but it's up to you to decide if that's important or not.

Regards,
Owen
 
Hi, I am one of the original group buy participants of the wire and I thought I would update you as to my progress.

Good news (depending on how you look at it)
I have finished placing all the components onto the power supply board.

My progress was halted after I wanted to kill life it's self after the frustration and pain I experienced placing the smallest resistors on the underside of the board. Oh such pain, I put the project back in the box and left it for over a year.

Today I gave it another shot and I can easily say that I have never been more humiliated in my life by something I have attempted to make.

I haven't tested it yet to see if it works and I may not for a while but it sure looks like there is no possible way it will work.

I am testament to the fact that SMD is not for everyone.


I am not looking forward to building the actual amp but I will give it a go sometime.
 

opc

Member
Joined 2004
Paid Member
Null Object:

Which parts in particular are you having troubles with? Is it because the parts themselves are too close together, or because they are simply too small?

Which iron and tip are you using? Are you using enough heat? Are you trying to use lead free solder? Are you using flux? Do you have someone in your area who could give you a quick hands-on tutorial?

I can honestly say that I sympathize with your experience, and I too have felt much the same way when I first started soldering SMD parts. I remember thinking "What a pain this is! Why not just use PTH parts?". I also remember my friend (who taught me at the time) looking at my work with a grimace and saying "yeah, it's not that bad" in a very unconvincing manner.

It was me pushing myself and my skills that led to me getting better at soldering the SMD parts. After a few projects, I was as good at mounting those as I was at PTH parts, and after a little while longer, I was much faster with SMD and started dreading having to get my wire clippers out when I had to solder PTH parts.

Short of an actual physical disability, like extremely poor sight or uncontrollably shaky hands, I don't see what would stop anyone from learning to solder. A big part of the problem is that most people learned to solder PTH parts so long ago that they forget the learning curve they experienced with those. I doubt anyone was making perfect solder joints on their first go at soldering PTH parts either! Learning a new skill, particularly one that is challenging, is going to be tough. You're not going to be an expert on the first go, even if you imagined you would be.

Let's see if we can't at least get you set up with ideal conditions, and then maybe get you to have another go. If you feel that you've ruined your board, or you need a few more SMD parts, I can send you some to replace them.

Don't give up so easily!

Cheers,
Owen
 
Owen, you are such a nice guy.
I use a 10x jewelers loup magnifier, for inspection. The trick with passives is to put a small bit of solder on one pad, I use 15mil glow core. Then re-heat pad, that has solder on it, place part with small tip tweezers. Rest your hand on the pcb to stop shaking. Easier to adjust for center, then when component is straight/flat, solder other lead/pasd. Having two small tipped irons is almost essential if you want to remove a chip component. Without you have to apply a lot of solder, on one side, so that the solder stays liquid, and then move fast to heat the other pad, it ain't easy.
A well tinned tip is also important, since you need very little solder.
Also have some small width solder braid, use it if you apply too much solder to a pad.
I have never had to use liquid flux, for passives, it just makes big mess. I find there is more than enough flux in the solder itself.
Liquid flux is necessary if you want to do a lead re-flow using hot air.

Owen, BTW, how is your position, at your employer, knowing the turmoil of late? I have been in situations like this before and can vouch that it ain't no fun.

Take care
Rick
 
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The one device that made SMD a million times easier for me was this..

elenco-soldering-heatsink.jpg


I know its purpose is technically a heat sink but clamping the part onto the pcb made a world of difference. 2nd was a flux pen, can never have too much flux.
 
I second Owen; don't give up! I'm 56 with failing eyesight, and over the past few years of practice have gained acceptable competency laying down 0603 and up, and quite a few different packages.

In addition to practice, the right tools make a world of difference. A good soldering station, tips, huge magnifying light, tweezers, etc. All together, they make a world of difference.

I'm one of those who prefer SMD to PTH work. Faster, cleaner, often better performance - I second Owen, don't give up! Tale a deep breath.
 

opc

Member
Joined 2004
Paid Member
Owen, you are such a nice guy.
I use a 10x jewelers loup magnifier, for inspection. The trick with passives is to put a small bit of solder on one pad, I use 15mil glow core. Then re-heat pad, that has solder on it, place part with small tip tweezers. Rest your hand on the pcb to stop shaking. Easier to adjust for center, then when component is straight/flat, solder other lead/pasd. Having two small tipped irons is almost essential if you want to remove a chip component. Without you have to apply a lot of solder, on one side, so that the solder stays liquid, and then move fast to heat the other pad, it ain't easy.
A well tinned tip is also important, since you need very little solder.
Also have some small width solder braid, use it if you apply too much solder to a pad.
I have never had to use liquid flux, for passives, it just makes big mess. I find there is more than enough flux in the solder itself.
Liquid flux is necessary if you want to do a lead re-flow using hot air.

Owen, BTW, how is your position, at your employer, knowing the turmoil of late? I have been in situations like this before and can vouch that it ain't no fun.

Take care
Rick

Hi Rick,

All very good advice, but I would deviate a little bit by saying that a good 2mm or 3mm chisel tip is optimal for parts 0805 or larger. Using a needle tip can be more challenging for beginners, but obviously necessary if you want to start soldering or re-working 0.5mm pitch IC's or 0402 and smaller passives.

You also mentioned flux and solder braid, both of which are absolutely necessary if you really want to do a good job and make your life easier. I don't regularly use liquid flux on passives, but it always makes the joints easier and nicer, so I would certainly suggest it.

Here's my personal list of things one should have to solder SMD parts:

- A good soldering iron with a 2mm or 3mm chisel tip.

I use one of these:

Weller WD1001 85w/120v Digital Single Channel Silver Series Soldering Station - Amazon.com

With this tip:

Invalid Request

- Copper braid (with flux):

Invalid Request

- Flux Pen (you might need to buy this locally, shipping is tricky):

835-P MG Chemicals | Mouser

- Tweezers:

Invalid Request

- Good solder (I always use leaded solder because it's oh-so-nice to work with):

Invalid Request

- 99% isopropyl alcohol (for flux cleanup after soldering):

Amazon.com: Swan Isopropyl Alcohol, 99%, Pint, 16 OZ: Health & Personal Care


As for the job, things have been alright so far, but it's touch and go and nobody knows what is really going on long term. The not knowing is the worst part for me.

mcandmar:

I have never used one of those before, but if it works for you then I wouldn't argue!

I tend to use the method described by rick above. I find the pad with the highest thermal mass (the one on the GND plane side if applicable) for the part I want to solder. I tin the pad itself with a little solder and and let it cool. I then grab the part I want to solder with tweezers in one hand, hold it flat on top of the tinned pad, and then use my other hand with the soldering iron to heat the joint until the part drops down and lands on the pad. I center the part on the pads while I keep the iron on the joint (work quickly!) and then I quickly remove the iron and let the joint solidify. With the part soldered correctly on one side, I simply spin the board around and solder the next side which is very easy because the part won't move. If you're fussy, you can go back and touch up the initial joint to make it pretty.

Cheers,
Owen
 
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Lots to say, on the SMT subject. Could write a chapter, but actually showing some one would take about a few minutes for each package technique.
I have my diy pcb's all done with HASL plating, so that their is already solder on the pads. This plating practice is frowned upon by the CM's, because of co-planearity issues, but for DIY, it help's a lot. In many cases you do not even have to pre-tin the pads, just heat one side, stick the comp, while solder is hot, then do the other side, follow up with final add of some extra solder both sides to make a nice tapered fillet.
I have "like extremely poor sight" but being myopic, helps so much., so much so, that I can read the codes off a 0805. Take my glasses off and I walk into walls. Glasses are a PITA, but for SMT soldering, it is like having built-in magnifiers. And people want laser eye surgery :)
Making 0603 or smaller for diy should be frowned upon, unless that is the only size that the comp comes in. I like 1206, as it is forgiving, but 0805 seems to be more of a standard.
 
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My first mistake with smt was in using magnifying glasses from the get go. If I had expensive ones or an operating microscope it would help, but that can't be easily obtained. Next time, I'll just hold the piece and bring in the solder iron. Also, a noobie needs a 2 mm chisel tip. With a needle tip, the solder rides up and away from the tip for some reason. It required turning the iron on its side. 0603 shouldn't be allowed in a diy project though. Order lots of extra capacitors of the small sizes as you will burn them up.
 
Is there an update BOM for the PSU for the wire. I found the one using the 317 and the 337 but not for the new TPS7A3301 . Could some one direct me to the post.

Looks like OPC has it here

http://www.diyaudio.com/forums/atta...vailable-here-bal-bal-se-se-lpuhp-psu-bom.pdf (opens pdf)

In this post in his Vendor thread for the Wire

http://www.diyaudio.com/forums/vend...e-here-bal-bal-se-se-lpuhp-3.html#post3699950

Those TPS7A3301's look like excellent regulators!
 

opc

Member
Joined 2004
Paid Member
Be warned, the reg's need to be electrically isolated from the heatsink. The isolation material listed within the BOM wont do the job. OPC posted a warning for both the PSU & LPUHP's PSU a few pages after the PSU BOM.

Paul

Indeed!!!

I will post the new BOMs this evening for all the boards as Google spreadsheets which will allow me to make changes if anyone finds errors.

It will also allow people to add Mouser or other part numbers to the list which will make it easier for all who need to buy parts.

Sorry for the delay on this, there's a lot going on, and I've been prioritizing getting board orders ready to ship.

Cheers,
Owen
 
Hello OPC, when will you be taking orders again on a run of these kits or boards? I also wanted to ask if you ever gave any thought to producing high performance DACs? You remind me of another designer/engineer from Canada, named CAaudiocollector. Out of the box thinking, and very knowledgeable. Thanks.
 
Hi everyone! I will be building the BAL-BAL version soon and have a couple questions for you fine folks :)

1) What is the recommended toroidal for the BAL-BAL? 10VA, 20VA, 12v, 15v?
2) Alongside #1 what's a good IEC/fuse and switch?
3) My Yulong DA8 DAC bal out is 4.2v and I'll be using the internal preamp with HD-800 headphones. Will unity gain suffice, or do I need to raise it? If I do, what are the recommended resistors to switch out?

Thanks so much in advance!
 
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