AKSA100 Balanced Input Conversion

AKSA · « **Reply #20 on:** 13 Jan 2006, 06:12 am »

Hi Patrick,

Let's answer these further concerns as you wrote them!

PA: So a 22 uF, 25VDC Nichicon Muse FS would work fine? Probably break in faster too!

HD: Yes, indeed, this would be fine, and there will be hardly any break-in.

PA: So just to be absolutely clear, the 2.7K resistor should go from the input side of C1 to ground, right? ground here meaning EARTH on the PCB i.e. star earth?

Earth on the pcb is sig earth, the pin near signal HOT. Star earth is on the power supply; gotta be careful of the distinction!

PA: Ah, now I'm confused - C1 is already a 22 uF Black Gate in my amp -- presumably because I've done the N+ upgrade. Does this mean I don't have to replace C1?

That's cool, Yes, keep it in.

I think we have it now, Patrick, these were relatively minor concerns.

Can't wait to hear your comments about the sound....... and you, a music industry man, WOW!!

Cheers,

Hugh

J Harris · « **Reply #21 on:** 13 Jan 2006, 05:08 pm »

Great, thanks Hugh - can't wait and will report back.

Final question - I just noticed that my Neutrik XLR jacks come equipped with a metal grounding tab as well as the 3 wire inputs.

Should this tab be connected to star earth? or chassis earth? or just experiment to see which has the least noise?

Best
Patirck

AKSA · « **Reply #22 on:** 13 Jan 2006, 09:37 pm »

Hi Patrick,

Ah, yes, connect the XLR earth tab on the plug to Star Earth - power earth. It's definitely the best method, as there are signal and power earths and the signal earth should be shielded somewhat.

Cheers,

Hugh

skrivis · « **Reply #23 on:** 13 Jan 2006, 09:45 pm »

Quote from: AKSA

Generally, if you have a noisy environment with long interconnects, it will be quieter

But won't the combo of low input impedance with long IC be worse? Like the cure is worse than the disease?

J Harris · « **Reply #24 on:** 14 Jan 2006, 07:21 pm »

Man, I just noticed there's a drawing of the entire 100W PCB, with components clearly marked, on page 31 of the manual. Somehow I completely forgot about the existence of this - makes it much easier!

Best
Patrick

J Harris · « **Reply #25 on:** 14 Jan 2006, 08:48 pm »

I'm embarking on this now - it seems to be extremely simple since my amp is already upgraded to N+ which takes care of much of the work.

Just one last question Hugh (I'm going to go ahead and do this anyway) - the input side of C1 seems to be the same, electrically speaking, as the HOT pin since they are directly connected by the trace on the circuit board.

Nonetheless, I'll run the 2.7K resistor from that pin of C1 rather than from the HOT input pin... to the GND input pin.

Hope I've got this right. There must be some principle of design or building that I don't understand here.

Best
Patrick

AKSA · « **Reply #26 on:** 14 Jan 2006, 09:24 pm »

Patrick,

That will be fine, the pin is exactly the same as the input to C1!

Cheers,

Hugh

J Harris · « **Reply #27 on:** 14 Jan 2006, 09:59 pm »

OK, I've done the left channel, hooked it back up (balanced on left, single-ended on right), and it sounds fine!

RFI unfortunately seems to be about the same... I'm not quite sure yet (because the right channel gets it worse, due to its placement or something).

The sound seems to be quite similar... I should really put on a mono record to be sure... but I think I'm just going to go ahead and do the right channel now.

Thanks Hugh!

Best
Patrick

AKSA · « **Reply #28 on:** 14 Jan 2006, 10:34 pm »

Patrick,

How can you be sure the problem is RFI? Do you have a steel case around the modules? Are the trafos close to the modules?

Are there lots of cellphone repeaters on the roof of your block?

Cheers,

Hugh

J Harris · « **Reply #29 on:** 14 Jan 2006, 11:34 pm »

Hi Hugh,

I think it's RFI because I can hear a radio station sometimes, distantly.

No, the case is not closed right now - I haven't drilled the back panel for the XLRs yet - they're hanging loose (carefully) for testing, and I still need to get a 1" step-drill bit to make the large holes required.

The trafos are about 1" from module (left) and nearly touching (right - sitting further forward due to presence of switch on front right panel). I'm using your standard enclosure if you remember, with some extra goodies that you threw in for me - but I may not have laid it out ideally inside.

There are definitely cellphone repeaters on buildings nearby, if not on my block - but remember I'm on a high floor only a couple blocks from the Empire State Building, which has radio masts all over it - along with all the other noise of midtown Manhattan.

I just got the right channel done, and am about to listen to both channels balanced (fingers crossed!)

Best
Patrick

J Harris · « **Reply #30 on:** 14 Jan 2006, 11:44 pm »

Both channels work!

After I drill the case and mount the XLRs properly, I'll start a new thread detailing everything I did and reporting on sound (which currently is great - immediately from start-up - though I don't know how different it is, if at all, from single-ended). It does seem to be a trifle louder - I might have to adopt your suggestion about changing R11 to 2.7Ks. Maybe not. There's no distortion that I can hear - just a trifle louder. Perhaps due to a lower noise floor?? [EDITED]

Thanks for all your help as usual Hugh -

Best
Patrick

J Harris · « **Reply #31 on:** 15 Jan 2006, 12:01 am »

This is sounding better and better.

And I was wrong - now that both channels are balanced, RFI is definitely down. Once I get the case drilled and the top back on, it should improve more - though it does vary at different times of day so it hasn't had the acid test.

Patrick

AKSA · « **Reply #32 on:** 15 Jan 2006, 12:59 am »

This is really good news, Patrick.

I'm rubbing my hands together with glee here in Melbourne!!

It would indeed have a little more gain, but is it that much louder with the same volume setting than before, in single end?

Cheer,s

Hugh

J Harris · « **Reply #33 on:** 15 Jan 2006, 01:05 am »

It's a trifle louder. My BAT has volume readout so I can tell exactly what level I'm at - and I can definitely say at 16, say, on the volume control, the music is louder. But in a good way - more presence, more bass (but more controlled bass). [EDITED]

It's really really sounding good now. I couldn't even bring myself to take a record off just a little while ago.

This is gonna be amazing! My system is sounding as goooood as it ever has. Palpability, musicality, bass (I don't even my sub turned on).

I'll post a review when it all gets built in and settled in. I see posts here about using digital amps, getting more wattage etc. etc. I've heard a lot of amps... right now the AKSA - in my system, in my room, IMO and all that - is giving me the best of all worlds - having used Pass class A, SET, push-pull tubes, McCormacks and everything else - the AKSA 100 N+ in balanced mode is just perfect.

You rule, Hugh!

All the best
Patrick

AKSA · « **Reply #34 on:** 15 Jan 2006, 05:42 am »

Thanks Patrick,

Best news I've had all week!!

Thanks for the progress report, keep us posted!

Cheers,

Hugh

J Harris · « **Reply #35 on:** 16 Jan 2006, 12:28 am »

Update: I finally tracked down a step-drill bit that goes to 1" (I was this close to getting a third Greenlee punch - they are really cool).

Got home at 5:30 ready to mount the XLRs and found out that my drill won't accept the 1/2" hasp for the new step-drill bit! Argh - now I have to buy a new drill, or perhaps find an adapter for my current drill (which sounds like it could be a bit dodgy in use).

Either way, tomorrow is fortunately a holiday so I'll be mounting these at last.

Meanwhile still listening to them "loose" and loving it.

Patrick