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Gold A-1 Build with Pics - Page 2

post #16 of 24

Glad to see you pushing ahead with this. It looks good. It'd be nice to get some measurements of how it performs; in the absence of professional audio test gear you could hook it up to a computer (soundcard + RMAA), but no sweat if you just want to listen to it...

 

w

post #17 of 24
Thread Starter 

Wakibaki, thank you!  I may be able to get some measurements.  I will most definitely give impressions!

post #18 of 24
Thread Starter 

It breathes!  After checking voltages here and there and double checking wiring, I applied power to the thing.  No smoke!  I checked for DC offset, and the photo shows the reading - both channels were the same.  I plugged in a CHEAP pair of cans and listened with no input applied.  There's a little bit of hum, but I can correct that.  The only (minor) issue I have to chase down is that the pilot LED won't work.  That should be easy to solve.  I didn't leave it on long, because the finals aren't heatsunk and they do get HOT.  I need to get the heat sink extrusion drilled and get the finals on it.  I also need to install the toroid.  Once all that is done - and I get the pilot LED working - I'll give it listen.

 

A1breathes.jpg

 

A1DCoffset.jpg

post #19 of 24
Thread Starter 

I apologize for the low-light iPhone photos in the previous reply!

 

I thought I should introduce myself to you fellas.  I did just jump right in here.

 

First off, I am NOT an engineer in the sense that I have an electrical or mechanical engineering degree.  I was trained as a "sound tech" for theater sound in college way back in the seventies.  I have always been fascinated by music and the devices that either captured or reproduced music.  I made a few abortive attempts at becoming a musician over the years, finally accepting the fact that I have zero talent for that discipline.  However, I found I have good hands, I am logical, and although math has never been something I've excelled at, applied math I can deal with.  I discovered, too, that I really enjoy making things - not crafts, but things that do something.  I have done woodworking, some mechanics, some construction, some home wiring, and a lot of "electronic projects".  My first DIY build was a Southwest Technical Products Universal Tiger pair that I put together as a class project in college.  That was followed closely by a Dynaco 410 and PAS-3. Other kits followed them.  Many speakers also have come out of my efforts, ranging from live sound floor wedge monitors to the pair of Scan Speak two ways I use today.  I built several control panels and the power supply for a large HO model railroad, and helped wire the layout itself as well as install the DCC control system.  I've also put decoders in locomotives - that's tiny work!  I have a very small, almost casual, location recording service, and for it I have built and modded all sorts of stuff - cables, snakes, mic mods, mic preamps, mods to power supplies in compact mixers, etc, etc, et ceter rah!  The most fun builds I have done in recent years were Tim Ryan's excellent Seventh Circle Audio mic preamps - I built three T-15 preamps for me, and built four T-15's and a pair of C-84's for a friend.  Then there was the Mini3, and most recently the Project Sunrise tube amp.

 

The Gold A-1 (I really don't like that name very much...) is my first foray into true DIY.  Although I didn't design the circuit or etch the board (design I can't do, board etching - well, maybe!), the layout of the case, the selection of various components and the point to point wiring is DIY, in my estimation.  It's fun to do, and I'd rather do that than play a board game or sew!

 

I'm pondering the idea of, down the road, building a truly high end headphone amp - one with enough power to drive about any respected headphone, also containing a very good to excellent 96kHz capable USB DAC (something my Mytek doesn't have).  At the moment I am intrigued by the AMB M3, and the Panda headphone amp, which gets a lot of love and attention over on Rock Grotto.  For the DAC portion, I just don't know, although the Twisted Pear OPUS seems pretty nice.

 

So - that's me.  Builder, mostly; reader who is fascinated by what you fellas do; admirer of the designs, workmanship, ideas, and capabilities displayed in this forum.


Edited by sarals - 10/29/11 at 6:16pm
post #20 of 24
Thread Starter 

For anyone interested, if anyone is, the amplifier has been up and running for several hours now.  It works as it should, it's dead quiet, it's stable, produces no unusual heat, and it sounds very good.  Very good!  I'm using my iPhone as a source, on repeat, as I'm doing a little stress test and burn in.  Tomorrow I'll finish casing it up.  And do my nails!  wink_face.gif

post #21 of 24

Thanks for giving us your impressions, I wanted to use this amp with my DAC, but since I noticed I could buy a Graham Slee Novo kit, I wonder if the Gold A1 has better performance.

post #22 of 24
Thread Starter 

It's all done!  I posted some photos of it over on the "Show us your builds" thread.

 

Well, how does it sound?  Much better than I expected.  In fact, as it burns in, it sounds better, and better, and better!  I'll give you the audiophile impression: 

 

It's dead quiet, it has a black background.  With volume all the way up and no source connected there is NO noise, at all.  With a source connected, at full volume there is the faintest "hiss", which I suspect is the source component.  The turn on delay works perfectly - there are no turn on "thumps", and the DC offset is negligible, less than .1 MV.  At first, it sounded a little hard.  The upper mid-range had an aggressive quality which was exacerbated by my HD600's.  My dt880's were better, smoother (they have a slightly scooped mid-range), but now, six hours later, they are sounding dark and the HD600 is sounding neutral.  The amplifier has prodigious power - it drives my HD600's and dt880's to painful levels with no noticeable strain.  It's bass is tight, tuneful, and extended, and if the music calls for power - it's there.  For example, kick drum notes are not rounded - they have impact and decay, and sound just as they should (thwop!).  The highs are airy, open, and real - not exaggerated, not spitty, not hifi-ish, not brittle.  The soundfield is expansive if the music calls for it, and it is rock stable.  There is an excellent sense of space, with good delineation of individual voices and instruments.  There is no congestion in complex passages (once again, lots of power).  And, the thing just keeps improving as time goes by.

 

Right now I'm feeding it with a Mytek Stereo96DAC, about as clean a signal as one could find.  It does that DAC justice, too.

 

I'll connect it to my DAW soon and run RMAA and see what that says.  My ears say "nice"!

 

I'm happy with my "experiment".  The total cost for this project was less than $100US, and if I had hated the amp, I still had a case and power supply.  I purposefully did NOT get spendy on the thing - no ALPS pot, no Neutrik connectors, no filtered AC mains, etc.  And, so what?  It sounds pretty freakin' good just as it is!  Now, I can throw that unspent money at my next project.  Whatever that will be.  L3000.gif

post #23 of 24
Thread Starter 
Quote:
Originally Posted by zest View Post

Thanks for giving us your impressions, I wanted to use this amp with my DAC, but since I noticed I could buy a Graham Slee Novo kit, I wonder if the Gold A1 has better performance.


You are welcome!  I don't know the Graham Slee Novo.  I do know the Matrix Quattro, the Mytek Stereo96DAC, and the Zero DAC.  This amp is on a par (right now) with the Matrix Quattro (my memory is serving me!), it's about as good as the head amp in the Mytek (the Mytek is just a tad smoother, but the Gold is more powerful), and it SLAYS the head amp in the Zero (no contest).  In my opinion, you'd be happy with it!

post #24 of 24

I just finished the break-in of the A1-Gold. I have the naked card, still to be put in a case.

I 100% agree with the impressions of Sarals.

This amplifier has a lot of muscles! biggrin.gif

I tested it with Superlux HD662 and HD668.

The sound is satisfactorily clear and detailed and the dynamics is its strong point. 

For the DIYers I recommend a transformer of not less than 20 W and an efficient heatsink for the 8 final transistors.

In my implementation in a box I will add a relay that will automatically switch the input to an external amplifier when the A1-Gold will be switched off.

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