[BUILD] 1176LN Rev D DIY

[Bri]

Thanks Ed!

--Brian

 

[Stagefright13]

Thanks from me 2 Ed money sent...

Cheers


(Edit) Recieved yesterday. Thanks again for helping everyone and the super fast shipping! Two thumbs up :thumb: :thumb:

 

[kdawg]

I happen to have a UTC o-12 transformer and a PEC 600 ohm dual deck UA replacement pot and was wondering what the correct wiring / resistors should be if I was going to mate it with the new Mnat Rev D board. I see a 270R resistor already there across the input to ground.

I built the other rev Mnat board a long time ago but added that o-12 input stage - was never quite sure if it was wired correctly though.

thanks
-kdawg

 

[kazper]

Well someone sniped the bid away from me. It looks like they have a big appetite for 600 ohm T-pads.

 

[ap123]

I did snipe but I was not the lone sniper! I did not win; that's how I know. I am disappointed to see that the winner was not a member of this forum. Perhaps it was a surplus shop.

I have been in touch with the seller and he has more units. He sold me 10 for $225 which I intend to sell on the black market for $22.50+shipping. I am not going to post this on the black market until I have them in my possession. Apparently he has more in storage but they're buried in a storage unit packed floor to ceiling with NOS ham stuff (a gold mine, if you will). The guy is extremely cool and very supportive of the DIY spirit. He said he couldn't resist as most of his personal ham equipment he built himself. Newark now charges $155 for these! Ugh. That should speak volumes for how cool this guy is.

 

[Stagefright13]

Wow that's a cool guy.

I didn't bid either didn't want to jack the price up. But I'll keep my eye on the black market unless I can pre order one. Let me know.

Thanks

Oh and I finished my board today. A real beauty! Thanks Mnats

 

[kazper]

I was trying to pick up a few output transformers from cinimag and there out of stock for a few weeks. I think it will allow a few of us more time to scrounge for t-pads. Just passing the info to the list. Maybe Ed scored there last few units and caused the lack of transformers..

 

[ap123]

http://www.groupdiy.com/index.php?topic=257364#257364

As promised here is my notification in the rev d thread about the 9 T600 attenuators I have on the black market.

[sold out]

 

[ap123]

8 iterations of king crimson red later and I finally got audio through the mnats rev d.

edandersen *did* at one point suggest the radio shack 1:1 isolation transformer...and at $3 I couldn't resist. I can't listen to my recording test because I don't have any monitors beside cheap headphones, however, I will say that the radioshack "greenbud" (it's green and weighs exactly 1/8 oz, really!) is conservatively rated at 300Hz to 5KHz. Surely lower than 300hz is passing here. This file is a martin d-something > sm-7 > chandler germ > 1:1 Isolation Transformer > mnats 1176 rev d > CM-96731 > apogee ensemble.

1176test2.mp3

Please excuse my lame noodling I'm really tired.

 

[Stagefright13]

That sounds good maybe we can add a IRON switch to the faceplate for switching input trannys! LOL I can't believe that thing is only 3 dollars. And Congrats for getting it up and running!
:thumb: :thumb:
Speaking of input transformers. I still haven't decided what to use. What is everyone else using on their version? I almost bought an 0-12 but got outbid. I am now thinking about getting something else that is more readily available. Any suggestions? I did some reading but came to nothing conclusive. I was kinda leaning toward keeping it fairly original sounding...

 

[ap123]

I can't really tell how the highs are getting through with this radio shack transformer but I think it's somewhere passing below around 8k. I can't stop playing with it...total blast. I was up late last night reading the official urei docs on calibration and I'm definitely going to need to find someone with a scope to help me. I don't know when I'm supposed to buy a scope...perhaps it is time. The circuit appears to be in complete working order and I am no electrical engineer by any means. I accidentally wired the release pot backward according to the front panels I've seen...but other than that it is in sound working order sans calibration/setup.

I intend on running two channels off of one 30VA 30+30 avel lindberg transformer. VR1 seems warm but my 2N3053 seems quite hot even with the heatsink on it.

The 3 deck T600 mallory was easy to hook up after looking at the purple schematic (which conveniently has both the bridged T and non bridged displayed). Unfortunately, the wiring of the bridged T is beyond my mental capacity at this point. I responded to an old T600 thread on the drawing board but I think many folks are entirely sick of hearing about the T600. I suppose I could just start guessing...but the bridged T was $75 and I'd rather not cover it in solder

Anyway...thanks mnats!

 

[Stagefright13]

There are some nice looking scope programs online for download. They use the soundcard for input. Dunno how good they are but I saw a cool looking dual trace one with free 14 day trial. :wink:
I am just starting to fully study this project right now. I have just about everything and the board is stuffed. I was side tracked for a while building some Eisen pres and the Drip LA2A.

Off topic but I purchased some pres from Eisen and Jens suggested I check this board for Baumans 2*5*2*0* clones. So I did and was like HOLY CRAP these guys are building la2a's and 1176's, etc. here!! I was shocked lol! So I joined asap. Thought you all would get a snicker out of that...

 

[kazper]

I've been in contact with Cinimag regarding a input transformer and david Geren passed on this info regarding another o-12 alternative.

We have a new transformer (only 3 in stock, though) which will do the O-12 job with saturation level more similar to it. This new transformer is the CMMI-2PCA. Its impedance in 37.5/150:600. Strap the primary in series and hook it up backwards for 2:1 step-down.

There under $45 each.

 

[nerd]

I've been in contact with Cinimag regarding a input transformer and david Geren passed on this info regarding another o-12 alternative.

We have a new transformer (only 3 in stock, though) which will do the O-12 job with saturation level more similar to it. This new transformer is the CMMI-2PCA. Its impedance in 37.5/150:600. Strap the primary in series and hook it up backwards for 2:1 step-down.

There under $45 each.

This could be really cool. Finding an o-12 has proven very problematic for me and I think the UTC alternatives (A20, A21) would lack the saturation charateristics of the o-12. Did he provide any more details? I already have an order with them, I would love to tack these onto it. Also... The price seems right.

 

[ap123]

There's also the Altran C-3837-1 O-12 reproduction. I'm not sure if Edandersen is acquiring those or not. I'm planning on doing two group buys, one for PEC Bridged Ts and the other for Altran C-3837-1s. The minimum qty is 30 on the PEC; not sure on the Altran I am contacting them today. Again, there was some talk about edandersen getting them but I haven't heard anything else about it and assume it's no longer happening.

 

[edanderson]

i do have an order in for the altran input transformer. mako is working on a new input transformer pcb to make all of the input transformer options a bit easier to use. i think even the newly announced cmmi-2pca should drop right in to the pcb.

in any case, i should have some c-3837s in stock within two weeks if altran keeps to their delivery schedule. bear in mind that i ordered them nearly five weeks ago.

ed

 

[edanderson]

as for the PEC attenuators, i was thinking about doing an order of those also, but not for another few weeks; too many irons in the fire. if aaron wants to order them and take care of it, he should go for it.

ed

 

[ap123]

Cool.

Reserve your PEC Bridged T on the black market. I was just going to wing it and order 30 but I figured this might help those who aren't on the forum all day with a chance to get in on these.

Aaron

 

[BladeSG]

Hi all... quick question.

I'm having a little trouble finding ceramic caps in 200pF (C3,C6). If I use 220pF is that going to cause problems? (I'm thinking it shouldn't matter)

Thanks in advance

P.S. If anyone has any 2N3391 transistors spare that you'd like to sell me, pls PM.

Steve

 

[Lowfreq]

I just paralleled two 100pf caps.