Looks great.

Future T2 builders will like this:

What's that?

Think of Dr Gilmore's digital attenuator and the Arduino controller (hopefully) all mounted on the T2's amp board.

Wow! What a nice idea.

Wow, got a part number for the mil-spec connector for this? This needs more than 15 wires per umbilical cord now, right?

Also, does the new revision include a switch for bypassing the attenuator all together?

Actually there is one spare pin in each of the power supply connectors.

So there is room for the +5 volts.

And the 12 volts for the attenuator can share one of the existing 12 volt power supply

wires that go to the servo.

Or add another connector to power the attenuator.

Its a work in progress, need to find a space for the cpu.

Where does one find ixys10m90s three terminal current regulators? I need 13 of 'em.

I tried all the usual suppliers: mouser, digikey, allied, bdent, Audio Lab Of Georgia, Rich Tech, LittleDiode... even eBay. I'm having problems even finding the data sheet for this part....

Mouser still has a lot of them... pretty sure it won't turn out anything if you type 'ixys10m90s' in the search box...

usa only...

http://www.mouser.com/ProductDetail/Ixys/IXCP10M90S/?qs=sGAEpiMZZMuNY54QelN3z%2fGpmPBImucviXo%2flzMMtuQ%3d

http://ixdev.ixys.com/DataSheet/98729.pdf

It's actually is IXCP10m90s instead of ixys10m90s.

Ahhhh OK, IXCP10M90S is the correct part number. Yeah I had come across IXCP10M90S and was trying to find a datasheet for IXYS10M90S to see if the two part numbers had the same characteristics.

My BOM shows IXYS10M90S, I wonder if there is an updated DIY T2 BOM someplace that I missed seeing.

IXYS is the mfg name, I see

Getting closer to having all the parts; I have the transformers, most of the silicon, will be ordering the passives tomorrow.....

Edited October 11, 201114 yr by Milosz

The first T2 we built which had noise on the right channel (we got that out) then developed noise on the left recently. In working on the right side we replaced many parts, including some resistors (changed to Xicons), the sound finally went away after we changed the pots. Before that though we had changed all the resistors in one battery on the right side. Sometime later, a few months, the left side started with some noise, so we replaced the pots and it was gone.

Recently, the noise came back on the left. So, my theory, based on absolutely nothing but a feeling, was that there is some strange interaction between the pots and the PRPs or Rikens (had a few of these in the batteries).

Yesterday we changed out all the resistors in the batteries for Xicons, result, no noise. Not saying we solved it 100% yet since we only ran the amp for 45 minutes, but the sound had always showed up by that time.

The only other thing which was changed was the nylon screws for PEEK, since I am thinking of selling this baby.

I know there are guys out there who used exotic resistors and have noise. It may be worth a try to replace them. Let us know if you already tried that and it did not work.

To be really clear, I have very, very little technical knowledge of the circuit, close to nothing, so this is just based on a hunch, intuition if you will.

Spritzer, did you ever get yours working properly?

I have some oscillation, no 'noise' though. I'm using Dale resistors in the batteries, as the Xicon are slightly inductive I have found. I think my issue is related to the position of the feedback resistors, and I haven't had a chance to verify that.

Edited October 12, 201114 yr by luvdunhill

Hi Blubliss,

I use PRP resistors and I also have noise problem. I'll try to change all the resistors in the active battery and see if I can get all the noise out.

Thanks a lot for your info.

Wachara C.

Hey Andy, has the second T2 ever had noise issues? Did you use Xicons exclusively?

No noise at all in the second T2 and I used all Xicons. KG has had no noise and he used all Xicons. From what I have seen/heard here, everyone who used PRPs has had the same noise problem and have not found a solution yet, except for maybe Inu??

I still have a few PRPs in T2 #1, but not in the batteries. If I were the other builders I would experiment first by changing all the resistors in the batteries to Xicons.

Inu also made circuit changes to the batteries that no one else has.

True.

One more thing I just remembered. When we were working on the right side, trying to find the noise, we also changed the PRPs to Xicons around the DJ8s. I do think the problem is in the batteries though, since I could change the noise by adjusting the pots.

Thanks for posting this info. Xicons it is.

I know most people are tight lipped about selling things.

It would be interesting to know what the market would bear for an original KG DIY T2.

I'm sure it wont go for cheap. If you post it for sale in a forum with an asking price, please let us know.

Marc, which series of Dale resistors did you use? Was it RN60D?

If I sell it, it will go to someone I know and can trust, not some random person. Probably not going to list it at all and I am in no hurry to sell.

Spritzer, did you ever get yours working properly?

I have some oscillation, no 'noise' though. I'm using Dale resistors in the batteries, as the Xicon are slightly inductive I have found. I think my issue is related to the position of the feedback resistors, and I haven't had a chance to verify that.

I haven't even looked at mine since July but one side on my unit is dead quiet while the other one has noise issues. Could be the resistors but Kevin suggested 3675's which were borderline that could be the cause.

Are you using CCF or CMF's? I've started to use CCF's in most of my projects now given how cheap they are and that Krell used to use them...

Spritzer, fyi, I replaced most of the 3675 on the first quest to get rid of the noise, no dice. Your noise is exactly the same as mine. I heard the mp3.

And on the first T2 we built one side was dead quiet and the other noisy, like yours.

If you'd like, you can send it to us and we'll repair it for you .

Edited October 12, 201114 yr by blubliss

Will you redo the PSU for me to? Bloody thing hums after the whole transformer fiasco....

Looks like I'll be ordering some resistors. Not that I don't have a Mouser shipment already on the way...