D-EF47 Tribute To Oliver Archut U47 Build Thread.

[Matt Nolan]

I'm having a problem figuring out  which way an AMI T47 transformer mounts on the board.  The transformer itself has no indication of which pins are A-B or C-D.  I looked at AMI's website and they show a bottom pic of the transformer with A-B and C-D but there is nothing that indicates which pins are which.  How can I determine A-B and C-D on the T47?

Inject small signals across various pairs of pins and measure or scope the remaining pair. After a few attempts, knowing the supposed ratio of the transformer, you can work out what is what. Difficult to tell phase without a scope though...

 

[jackinthebox]

I'm having a problem figuring out  which way an AMI T47 transformer mounts on the board.  The transformer itself has no indication of which pins are A-B or C-D.  I looked at AMI's website and they show a bottom pic of the transformer with A-B and C-D but there is nothing that indicates which pins are which.  How can I determine A-B and C-D on the T47?

see attached pic. the T47 spec sheet shows the pins labelled A,B,C,and D. As does the PCB, but it is a bit confusing which pins are which on the transfomer itself. Pin A is the one closest to the 'T' in T47 on the pins side of the transformer.
Hope this helps!

 

[vinylwall]

I'm having a problem figuring out  which way an AMI T47 transformer mounts on the board.  The transformer itself has no indication of which pins are A-B or C-D.  I looked at AMI's website and they show a bottom pic of the transformer with A-B and C-D but there is nothing that indicates which pins are which.  How can I determine A-B and C-D on the T47?

see attached pic. the T47 spec sheet shows the pins labelled A,B,C,and D. As does the PCB, but it is a bit confusing which pins are which on the transfomer itself. Pin A is the one closest to the 'T' in T47 on the pins side of the transformer.
Hope this helps!

Thanks so much.    Just the info I was looking for.  Take care.

 

[vinylwall]

Well that's a bummer.  I mounted the T47 transformer on the board, but it is too tall to fit inside the 47 style mic bodies I got from Andrew in Lithuania.  I also tried it in an MK-47 body from Chunger and it won't fit in that one either.  Are you using some sort of trick to mount the PCB in the body?

 

[jackinthebox]

Well that's a bummer.  I mounted the T47 transformer on the board, but it is too tall to fit inside the 47 style mic bodies I got from Andrew in Lithuania.  I also tried it in an MK-47 body from Chunger and it won't fit in that one either.  Are you using some sort of trick to mount the PCB in the body?

what diameter is the body? if your transformer is fitted on the opposite side from the tube, you just need to make sure the transformer sits between the side rails. I've attached another picture which might help.

 

[poctop]

Well that's a bummer.  I mounted the T47 transformer on the board, but it is too tall to fit inside the 47 style mic bodies I got from Andrew in Lithuania.  I also tried it in an MK-47 body from Chunger and it won't fit in that one either.  Are you using some sort of trick to mount the PCB in the body?

what diameter is the body? if your transformer is fitted on the opposite side from the tube, you just need to make sure the transformer sits between the side rails. I've attached another picture which might help.

The PCB was specifically design to have package for AMI BV08 Classic Series and AMI T47 Transformer ,
Other transformer can be fitted as well.  Here is the 2 Mounting Strategies that will permit the Use of about any transformer.

https://cdn.groupbuilder.com/groupdiy/u/39511/58d028199479b.zip

from page 1 of this thread,
Best,
Dan,

 

[tommypiper]

Dan, will Max's Bv.08 work in this project?  Will it mount to your PCB? 

Can this build be made with an EF-804-S?  (It's such a good tube, and made specifically to avoid microphonics, I've been surprised no one has yet designed or built a microphone with this tube.)

 

[opacheco]

I have a question about the output transformers for this project.

Look like there are four transformers  BV8N, BV8R, T8, T47 and these fit in the board. 
Can anyone talk about how these transformers will effect the sound quality?

Any comment?
Opacheco.

 

[jafo]

Dan, will Max's Bv.08 work in this project?  Will it mount to your PCB? 

I have both here, pcb and xformer.
The mounting holes fit but the pins are different. You have to turn the xformer around and wire it to the pcb.
Best solution woud be a little helper-breadboard, where you lead the xformer-pins to a separate solder point. Otherwise you
have to solder the wires direct to the xformer...

Im waiting for the body and saving money for a capsule right now.
Will build the same combination. Max´s BV.08, D-EF47 PCB, with Thiersch-capsule in Andrew´s body 

Jan

 

[opacheco]

Any comments??

Opacheco

I have a question about the output transformers for this project.

Look like there are four transformers  BV8N, BV8R, T8, T47 and these fit in the board. 
Can anyone talk about how these transformers will effect the sound quality?

Any comment?
Opacheco.

 

[opacheco]

Any comments??

Opacheco

I have a question about the output transformers for this project.

Look like there are four transformers  BV8N, BV8R, T8, T47 and these fit in the board. 
Can anyone talk about how these transformers will effect the sound quality?

Any comment?
Opacheco.

 

[poctop]

opacheco

your inbox is Full,
D

PS: I will fix the Web inventory,
Edit , it is fixed now ,
Dan,

 

[opacheco]

Dan,
I so sorry for my full inbox; I will repair that now!

Thanks a lot for your time and help with this trouble.

Opacheco.

opacheco

your inbox is Full,
D

PS: I will fix the Web inventory,
Edit , it is fixed now ,
Dan,

 

[[email protected]]

Started working on this build. Got as far as I could go without mounting hardware. Just ordered a body from the talented Andrew.

Thank to both Dany and Andrew for making this project possible!!!

 

[[email protected]]

Can anyone offer the wire they used to wire-up the PSU? Are there generic wire kits of various gauges and lengths, or will I need a few small spools of what is needed? If so, what kind/types for this project?

Next, is I understand it is possible to use either the 24V(red) relay and rcoil resistor, or the 48V(silver) relay and matching resistor. How does one know which to choose? I purchased both and ended up mounting the 24V, but am not clear on if this is the best choice. 

Also, I ordered EF800 tubes online, but was wondering if anyone knows where to get good tested EF800 tubes for this type of application?

Thanks all and please forgive my noob questions.

 

[Phrazemaster]

Regarding the wire, folks like different stuff but I'm a fan of silver-plated copper wire with teflon insulation. I use about 24AWG for most hookup stuff, sometimes as low as 18AWG for stuff coming right off mains. I buy mine from bulkwire.com or Apex Junior; can google these for exact sites.

I don't know if Bowie (guy here on the forum) has the EF800 tubes but if so I would consider buying from him because he thoroughly tests most tubes. He's a little pricier but you get what you pay for.

I can't speak to the resistor questions.

HTH,

Mike

Edit: Forgot to mention - if you do go the teflon SPC route (silver plated copper wire), consider getting a thermal wire stripper. Teflon is notoriously difficult to strip, although some guys have a system for it other than thermal strippers. I bought one and never looked back! You never nick the conductor either, if you do it right.

 

[afdobbert]

Just have to say I've had my D- EF47 mic finished now for a few months, and it is the most beautiful mic I could ever dream of owning. I have a Thiersch M7,  EF800, and Oliver's classic BV08 in mine...it is such a stunning mic. I started DIY about a year ago with the dream of owning a U47-style mic, and here it is a year later and I have it. This forum really is an amazing place with some really special people. Thanks again, everyone!

 

[poctop]

I have been updating some of the capsule connection picture on page 1  as they were some errata in one of them
all fixed now , if you have a working mic then please ignore this post 
Best,
Dan,

 

[[email protected]]

Phazemaster! My Man! Thank you so much for the reply. Ive been busy lately, so sitting on this project hasn't been too bad. Gonna get the wire tonight. Ive been essentially following Vinylwalls PSU build. I liked the case with precut holes with binder. His is very neat and clean. His can be seen on page 4.

So, for this PSU, I can use 24AWG for the binder connectors, and power components or should I get 18AWG for power from mains? I have spare Gepco 8pr pieces. Its 24AWG. (GA72408GFC to be exact). Would this stuff work if I stripped a few pieces out?

For the XLR connector to PCB on the PSU, can I use a small strip of the Gepco 8pr?

Same for inside the mic body? Connecting the PCB to the Mics connector?



I purchased 3 tubes online a few months back. I sourced them from the site below. They arrived well packed and fresh.

http://www.nostubestore.com/2011/10/telefunken-ef800-germany.html

I'll look into Bowie if anyone thinks the place I got mine might give me issues.

I really do appreciate all the help. As afdobbert said above, this is a special place!

Thanks!

 

[TLRT]

Mine is ready finally! Aputis body, my DIY PSU enclosure with dual toroid, AMI BV08, Beesneez K7, sounds great, with very low noise level. Thanks to Dany/Oliver(R.I.P.) for the project!