REDD 47 In/Out Transformers

[Gearsix]

I am completing a p2p REDD 47 preamplifier ... and now it's time to buy the transformers!

For input I have the possibility to have these transformers:
1)Lundahl LL1538 (1:5)
2)OEP A262A3E (1:6.45)
3)Classicapi EA2622 (1:7)

Someone has tried them?

For the output I have seen that Carnhill produces a 15k:600 Ohm and a 9600:600 Ohm transformers
Someone has tried them?

P.S.
I know that Sowter and Cinemag produces some specific transformers for this preamp but I want to spend less

 

[ed rees]

That OEP looks decent for $15, and the option of 150 or 600 ohms on the input is nice. They have a mumetal can option for them too. I might try one out.

There's a set of $10 each Edcors that people use for the Orange 86. XSM15k/600 and WSM10K/150

 

[Mike Cleaver]

The transformers are key to the sound of this preamp and many other vintage units.
I say yes to experimenting and listening carefully to the results.
It may be possible to duplicate the sound of the original with less expensive transformers but the Sowters to me sound very close to the originals.

 

[CJ]

have not built that pre yet,

Winston liked a custom Cinemag, had a ratio similar to the OEP if i remember correctly,

tube selection and output trans will change things also,

 

[seavote]

guitarmaker built one (redd 47) and swore by a Cinemag CMMI-7C .
8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8)

 

[buildafriend]

I'll be using a CMMI 7C in mine, I already have it.

 

[Gearsix]

Thank you!
someone else who has used Lundahl and Carnhill transformers?

 

[Fablab]

I am interested, too about the results using Lundahl LL1538 as input in REDD 47 preamp

 

[ruffrecords]

I have used the Carnhill 9600:600 output transformer strapped for 2400:600 in the EZ Tube Mixer and it works great.

Cheers

Ian

 

[RuudNL]

I noticed that the OEP transformers (even with the shielding can!) are very sensitive to external magnetic stray fields.
They introduced a lot of hum when I used them as input transformers in my preamps.
After I replaced the transformers by Sennheiser TM003 types, there was a big difference in hum sensitivity.

 

[Gearsix]

Hi Ian,
the original output transformer has a 7:1 ratio while the Carnhill 9600:600 has a 4:1 ratio
Do you think it is ok for the REDD 47 preamp or I'd use the 15k:600 that has a 5:1 Ratio?

 

[okgb]

Most tube inputs usually have a higher ratio xfmr  , no ?
you'll get a better s/n as well

 

[ruffrecords]

Hi Ian,
the original output transformer has a 7:1 ratio while the Carnhill 9600:600 has a 4:1 ratio
Do you think it is ok for the REDD 47 preamp or I'd use the 15k:600 that has a 5:1 Ratio?

Good point. You asked if anyone had used Carnhill transformers so I assumed they had one suitable for this  project. I had used a Carnhill on one of my own projects and they were very good so I recommend them in general.

However, as you point out, this project really needs a 15K:600 transformer and Carnhill don't do one. Knowing the REDD47 circuit, I don't think you would get away with a 9600:600.

Cheers

Ian

 

[Gearsix]

Hi Ian, I have asked about the Carnhill 15K:600 output transformer because a have seen it in Audio Maintenance site (CA-18-VTB2380)
I think it is a new product

 

[ruffrecords]

Hi Ian, I have asked about the Carnhill 15K:600 output transformer because a have seen it in Audio Maintenance site (CA-18-VTB2380)
I think it is a new product

Yes, you are right it is a new product. I just looked through the Carnhill design guide and of course it is not in there yet. So, I would say that in general Carnhill's output transformers are good value for money and at the price the VTB2380 looks good too.

Cheers

Ian

 

[iprovlek]

I used hammond 560c for output and old vintage soundcraft trannie for input (1:7)...

Here is the link for hammond!

Hammond was ordered from Italy i forgot name of company for Hammond distributors!

http://www.hammondmfg.com/560.htm#560

Cheers1

 

[Gearsix]

Hammond 560C is a step up transformer (it seems to be an input transformer) while the REDD 47 output transformer is a step down transformer (7:1)
I am sure it works but it is far long from the original specs
Anyway, for the output I'll use the Carnhill as suggested by Ian
Considered what I have read in other threads, a lower ratio in output may be better
The question remains if I can use Lundahl LL1538 in input (it is1:5 instead of 1:7)

 

[ruffrecords]

The question remains if I can use Lundahl LL1538 in input (it is1:5 instead of 1:7)

I would think it will be fine. You will just have about 3dB less gain and possibly 3dB less S/N.

Cheers

Ian

 

[Gearsix]

Thank you Ian!

 

[ungifted]

Interested in subj too...

Found mic input/output recommendations from Edcor:

http://edcorusa.com/boards/topic/132/microphone-preamp-project

So we can try MX, MXL type. Somthing like this 1:8 http://www.edcorusa.com/p/112/mxl8cs
Has anyone used MX/MXL transformers as input for tube preamps like REDD 47?

Shielding is another story...