TG1 - advice from any one who has built it...

[oceres]

here

I bought it last year lol... I think it was from the first batch dunno

 

[crisotop]

I used on the same power supply for a Sontec build the following diodes:

D2, 4, 5, 7 = 1N5400
D1, 3, 6, 8 = 1N4004

hth, christoph

 

[oceres]

thanks christoph 

 

[tomcat]

Im little bit confused. Fester wrote somewhere:

---
Simplest way to build TG with iron and transformers bypass option
is to use 1:1 input and output transformers. In this case, use
1:1 input balanced line receiver and ommit output amp on bypass board.
Input trafo is 10k:10k Sowter etc, output is 600:600.
---

and

---
Another very nice sounding option is use of Neve 31267-like 10k:2k4
on input and Neve LO1173-like (70:600) as output transformer.
---

Somewhere else i found the combination from a crossref what chandler is using

VTB9045 & VTB9057

shouldnt it be

VTB9046 & VTB9057 (10k:2k4 & 50:600) ???

 

[Michael Tibes]

That's one of the many hard bits on that project - figuring out and digesting all the I/O options Fester had in mind.
1 - no transformers - input electronically balanced, output unsymmetrical (poor mans)
2 - as 1, but with 1:1 in and output trannys (10k:10k / 600R:600R) (EMI with trannys)
3 - with Neve type iron 2:1 / 1:2 - that's a 6 dB level drop at the input and a 6-8dB or so gain at the output
4 - the C. version with 1:2 / 1:3 trannys.
Version 2-4 have the option to bypass the transformers and replace them with the opamp curcuits on the I/O boards in order to make the bypass idea reasonable and therefore to maintain the gain structure.
One could also take this further and for example do version 4 with 1:2 / 1:3 trannys but keep the transformer bypass circuit at unity gain in order to have 2 really different flavours...

I hope I didn't confuse you even more 

Michael

 

[briomusic]

the ch*ndler version (aka option 4 in michaels post) and its history is explained in this post:
http://www.groupdiy.com/index.php?topic=6481.msg395357#msg395357

basically - in reply to tomcats post - what should be, gainwise, doesn't come into it....

to achieve the 1:2 (6 dB) boost on the input the VTB9045 does make sense, even though it is a mic input transformer used in a line level application. (whatever this means in terms of impedances is for someone else to explain...)
in fact, frank einstein reckons the primaries were wired in parallel for a blistering +12dB gain, however this is not reflected in the uncle fester variant 4.

as for the output transformer, in order to achieve a ratio close to 1:3 the 1166 type output transformer (VTB9057 or similar from Carnhill) would also need the primaries wired in parallel.

afaik, variations 2 and 3 are suggestions by fester and not based on cloning existing machines.

 

[Michael Tibes]

Just wanted to add that I remember something like 'a Neve mic transformer will not do here' from Festers description, I assume it can't hold the levels if used as line in and that Mr. C seems to have custom wound transformers on his version. I don't know enough about the suggested Neve line transformers for version 3, being 2:1 they'd be 1:2 if reversed, paralleling the prim coils would be 1:4? Maybe with even more relay switching all the versions could be done in one box?

I am currently still on 'phase one', just opamp balanced input and it already works great. It can certainly only get better with good transformers, but to get going that's a good starting point - and closest to the EMI channel version.

Michael

 

[tomcat]

to achieve the 1:2 (6 dB) boost on the input the VTB9045 does make sense, even though it is a mic input transformer used in a line level application. (whatever this means in terms of impedances is for someone else to explain...)

This is exactly the part which puzzled me  :-\ Was hoping to add the transformers to another order i have to do right now, well maybe i have to be more patient and build it discrete first.

 

[tomcat]

3 - with Neve type iron 2:1 / 1:2 - that's a 6 dB level drop at the input and a 6-8dB or so gain at the output

I hope I didn't confuse you even more  

Well you did

So regarding the option 3:

VTB9046 is 10k : 2k4 and both sides wired ins series create a -6dB Gain
VTB9056 is 70 : 600 and creates a +8dB gain

looks good on paper to me. Have to order these trannies anyway for a 33609 ... should be able to test this config.

Oh man ... audio transformers ... still a big mistery for me

 

[Hank Dussen]

Can't find the BC214's. Anyone knows a good alternative?
I searched the forum and there's some suggestions.
Someone suggested MPSA56 connected reversed.
Or maybe the BC184's will do?

The same goes for the BC177. Anyone knows a good substitute?

What did you guys use?

 

[Rob Flinn]

Can't find the BC214's. Anyone knows a good alternative?
I searched the forum and there's some suggestions.
Someone suggested MPSA56 connected reversed.
Or maybe the BC184's will do?

The same goes for the BC177. Anyone knows a good substitute?

What did you guys use?

Did you look on ebay ??

 

[Jim50hertz]

BC214 here

BC177 here

 

[baadc0de]

BC214 here

BC177 here

Yes but you can't buy anything on the first URL by virtue of everything being "No Longer Stocked" or "No longer manufactured". Bummer.

 

[Jim50hertz]

Aah, sorry dude, didn't catch that 

 

[Tekay]

How about BC550C and BC560C

 

[Rob Flinn]

Another place apart from ebay that you can get these transistors from is http://www.ssi-uk.com/

I even got the correct output transistors from them.

 

[Hank Dussen]

Thanks guys,
I'll check out SSI. Otherwise eBay.

Now another one:
I read somwhere that the transformers should be ungapped? Or was is gapped? Oh ****, now I don't know anymore...
How impotant is that anyway?
Is there a reason why cheap OEP's shouldn't work here?

 

[Michael Tibes]

There's no dc around, I don't see why the xformers should be gapped?

Michael

 

[simonsez]

I use BC550 and BC560, i don't think transformer  should be gapped...theres output cap there..

 

[warpie]

hi,

does anyone know if the lundhal LL1540 and LL1517 can be used here?