Newbie Transformer Questions............

Hello,

i´ve got a little Question about transformers, at the moment i´m building a dual channel 1176 (gyraf design, many thanks to denmark.....) and i´m going to use Lundahl Transformers on this one.

First Question: what´s about the input transformers, are they really important or could i do them later.....

Second Questionoes anyone have experience´s with Neutrik and Oxford Transformers?

Third Question:Could anyone give me a tip for a really good sounding mic pre, (api, neve.....style...) wich could be build at not as high cost???
(2x300? Transformers for a single channel are just to high for my momentary budget. :sad: )

Fourth Question:Anyone knowing the Urei 1108 Preamp, it´s totally simple and maybe i´m going to build one or two....could i just build it with Output Transformer???How will it Sound?

many thanks for reading and maybe answering...... :grin:

greets,
matthis

..about VU-Meters, what are really useable VU-Meters for the Urei 1176 Clone???Does anyone know those cheapo meters from the Electronic Store you get for 4,95.-Euros???Whats up with them, they can´t be exact!?!?
Does anyone know where to get those "moving coil" meter´s for Gyraf´s SSL Comp???
Thanks,

Matthis

The G1176 has electronically balanced input so an input transformer is not needed. Unless you want galvanic isolation and a wee bit o' iron sound. Actually, the Lundahls colour the sound so little, that you probably wont miss it.

Those Neutrik trannies are not good for this projekt. They're not really good for anything If you mean OEP by Oxford, then yes, they do rock! :grin:

You could clone one of rafafred's Langevin cards. Wouldn't set you back more than a sixpack + some decent input iron like a small Beyer. They're actually very nice those Langevins..

I'll have to look up that UREI, but I think it's quite similar to that Langevin I mentioned..

Can't help you with the meter question. Most/all cheap meters aren't VU, but that doesn't mean you can't use 'em..

www.waltzingbear.com/Schematics/Urei/UA_1108.pdf

That output trannie is going to be a customjob, I'm afraid.

How does it sound, anyone know? Anyone seen one on ebay?

many thanks for that fast reply, are those Oxfords really cool???They are so cheap (8Euro´s...).
where to get those langevin schem´s???
many thanks!!!

Matthis

for the urei 1108 i read that a lundahl 5402 would work, because of the this feedback thing.....maybe i just try it out....
thanks,
matthis

Langevin pre;

thanx for that schematic, tomorrow i´m going to get the parts and build it...what kind of input tranny would you use, and where to get???

Well, you cannot easily change the gain on that circuit.

This is what I did; I strapped it for lowest gain, 40dB I think, used a 10kOhm pot on the output an followed that with a Langevin AM4700 Linecard. The micpreamp by itself can't really drive anything. DIY'ing an AM4700 is really easy and cheap.

Use transistors rated at atleast 50V use a 45V PSU and you can use that for the phantompower too. Makes it a great deal cheaper..

Just put a jumper between the strap pins.

AM4700 schematic comming up in a few minutes..

You can buy a cheap Beyer or similar at ebay. Or use an OEP.

Langevin AM4700 (18dB gain);



Pics courtesy of rafafredd :grin:

Matthis if you mean the OEP's when talking about Oxford transformers and since you are also from germany i am wondering where you get them for 8 Euros ? The cheapest i found where 14 Euros (which of course isn't expensive for transformers). And remember this is the price without the screening cans. For example in the G9 Jakob really recommends to use those optional screening cans which did run me about 7.3 Euro per can. So one complete transformer was 21,3 Euros.

Flo

They both run on +45V. The 'supply -' & 'in low' are both ground/0V as you can see.

Have fun :grin: :grin:

If you have probs finding the transistors, you could probably use 2SC2240s for all transistors exept the Linecard output transistor (2N3053). Use a BD139 there. I have _NOT_ tried this though...

The R5/600 0hm (you can use 560 or 620 ohm) in the Linecard should be a 5 watter..

You'll need about 200mA 45V in total including phantompower.

i named the 8 euro´s because of the one i ordered from farnell.de for testing in the 1176.
in the moment i´m not as deep into transformers to know it all, but i´m reading..... :grin:
even the 21,3.-Euro´s you paid is a really good price for an transformer...(i paid 50Euro´s for a single Lundahl...)
..but let me say if the 50Euro´s Lundahl´s are really better i would buy them.
greets

The Lundahl may not be better as such. I really like what the OEPs does to the sound, more iron phatness imo. If you like it cleaner buy the Lundahl. It's technically a much better trannie, but you don't record specs, you record sound.

Well in my G1176 i also used a Lundahl and of course also paid 50 euros. Yeah 21,3 Euros are very cheap for a transformers, no complaints about this from my side. I just thought you meant the OEP's with 8 Euros.

I am no expert but i wouldn't say that the Lundahls are better than OEP. Lundahls are supposed to be very clean while the OEP's add more coloration. Besides the main reason (cost) this was the other reason why i equipped my G9 completely with OEP's for both input and output.

Flo

You may also need to build a switchable 20dB pad in front of the mic trannie...

Even if you think this preamp blows you haven't wasted more than a few dollars. The PSU and mictrannie can be used for other projetcs..

Also, ask rafafredd what he thinks about it :wink: :green:

thanks for the replies so far, as i said, tomorrow i´ll get the parts and start to build it.......i don´t worry about the transistor´s.I´ve found an old Radio&Television Shop in my neighborhood, they even had 20!!! ac109 Germanium transistors for me.
thanks so far, i´ll put Photo´s in this thread if i get it finished!
matthis

Dear Infernal_Death,
what type numbers of OEP´s you used in your project???

You cannot use germaniums in that project! Maybe _BC_109...