newcomb tr-91 diagram

[kiira]

would this make a good inputfor New York Dave's high gain pre?

 

[rafafredd]

It looks so...

 

[NewYorkDave]

Most likely, yes, and also the "One-Bottle" pre:

http://www.groupdiy.com/index.php?topic=6711

Although the secondary Z is not listed on your drawing, 50/200:50K was pretty common, so it's likely in that ballpark.

Thanks for the diagram. It'll be a help to me when I get around to futzing with the old Newcomb mixer that's sitting on my junk pile. The mixer didn't come with input xfmrs, but I have other 9-pin inputs I could use in their place (with sockets appropriately rewired, of course).

I could have traced it out without knowing the pinout, of course, but who has the time these days? :wink:

 

[kiira]

Hi Dave - do you have that 4 channel Grommes amp? It used Newcomb inputs I know. I think Grommes stuff is kinda cool .

Yeah it doesn't have the output Z on it. I just copied the diagram on the case.

I'm not sure how I would wire this to get a 1:10 ...

Would I use 5 and 8 from my input and then use 2 and 9 for my balanced out .. 1 to ground?

I really want to build your 6av7/12bh6 high gain pre as a mic pre for my low otput ribbon... it needs about 70 dB gain I think coz my Tascam m512 doesn't quite do it an it has 60dB.

I also have a UTC a-10... would that make a better input?


thanks.

 

[CJ]

inputsignaql to 5 and 8, strap 6 and 7 together.

for twice the voltage gain, tie 7 and 8 together, tie 5 and 6 together, and put signal on 6 and 7.

A-10 is a nice x-former-1:10 step up.

cj

 

[ciminosound]

Save your A-10 for your LA-2A! :green:

The newcombs are great mic input trannys. :thumb:

 

[kiira]

[quote author="ciminosound"]Save your A-10 for your LA-2A! :green:

The newcombs are great mic input trannys. :thumb:[/quote]

I have another transformer for the La-2a that's supposed to work ok too. It's an HA-100X or something like that. And an A24 for the output. I'm going to make this one nicer than my first one though with a really nice 3U box and everything, built on turret strip like I do guitar amps.

Kiira

 

[kiira]

[quote author="CJ"]inputsignaql to 5 and 8, strap 6 and 7 together.

for twice the voltage gain, tie 7 and 8 together, tie 5 and 6 together, and put signal on 6 and 7.

A-10 is a nice x-former-1:10 step up.

cj[/quote]

Cool. Thank you. this X-former is supposedly 1:10, so with the other wiring it would be 1:20? Which would you use for Daves high gain 6av7/12bh7 design? Or maybe I should wire a multi position/deck switch to go back and forth...

Kiira

 

[alk509]

[quote author="kiira"]I have another transformer for the La-2a that's supposed to work ok too. It's an HA-100X or something like that.[/quote]

Nah, those are rubbish... Send it to me, so I can properly dispose of it. :wink:

Peace,
Al.

 

[CJ]

Remember, A-10 better than HA-100X IMHO.

And also, as I have mentioned a million times before, 1:10 is way to high a ratio for LA2a.

You want a 1:1 10k:10k bridger in there. Look at the Jensen mod.

Try whatever for your preamp. Swap out different ones til you find the one you like.
cj

 

[kiira]

[quote author="CJ"]Remember, A-10 better than HA-100X IMHO.
[/quote]

So. I just wasted that $5. Dang.

And also, as I have mentioned a million times before, 1:10 is way to high a ratio for LA2a.

eek. It is? They are? There's lotsa UTC transformers on ebay but usually don't know what they're for or the specs.

You want a 1:1 10k:10k bridger in there. Look at the Jensen mod.

Try whatever for your preamp. Swap out different ones til you find the one you like.
cj

Ok. Thank you for the info.

Kiira