Condenser Microphones Toroidal Transformers Line-up

Hey Folks,

Some of you might already seen the topic of toroidal transformers for ribbon microphones in the 'White Market' section. Finally, I found a nice toroidal core for the condenser microphones. It is annealed 80% Ni tape wound core, with the size small enough to fit in MOST of the microphone bodies and could be used even as a direct drop-in in the MXL2001/67G mics. I have already worked out 6.5:1 (ratio of BV8, good for EF86, 6AK5, 5840 and many other tubes), 8:1, 10:1, and 12:1 ratios, but can make any ratio. The pri DCR is well under 100 Ohm (while most of the EI or DU cores are in kOhm range), the transformers are very low loss, distortions, and phase shift.

The main problem is the cores are outrageously expensive in small quantities, so I will need to order at least 50 pieces to make it worth. So the main questions are

1) if people interested in those transformers at all, and
2) how many people would buy them?

Best, M  

P.S. Not sure if it belongs to "Brewery", so moderators feel free to move it there.

would definitely be interested in 4-6, and possibly more depending on if they'll squeeze into pencil-style bodies as well.  can't have a go at them immediately though, too many financial sins that i already have to atone for.

brewery? group buy/pre order= market, black or white?
I am interested, cost pending. will you make raw cores available?

grantlack said:

would definitely be interested in 4-6, and possibly more depending on if they'll squeeze into pencil-style bodies as well.  can't have a go at them immediately though, too many financial sins that i already have to atone for.

Click to expand...

The transformer diameter is 1.250", so unfortunately, they won't fit the SDC body... but wait a second... there is a trick. For teaser, here is a cone I machined for MXL603 body. If there is demand I can make those (or even entire bodies) in quantities. Keep in mind, that one was for my old core, which was much bigger, so it is somewhat crude with its 1.750" diameter. It can be made much more elegant and thin:



To get an idea as for how the transformer looks, here is the pic of the ribbon mic transformer:

shabtek said:

brewery? group buy/pre order= market, black or white?
I am interested, cost pending. will you make raw cores available?

Click to expand...

The reason I posted it here is while toroidal transformers were used for ribbon mics (for example, Coles 4038, Oktava, Royer), the concept of toroidal transformers for condenser microphones is new and to my knowledge, never had been realized before. I thought this will spark an interest and we could start a discussion about toroidals, as their properties are by far superior than any conventional EI or UI lamination.

To answer your question, I can make the cores available. I think though, not many here have toroidal winders and to do it by hand is a BIG PITA!

If somebody needs custom made transformers, or wind any coils/inductors with any characteristics, multitaps, then it is no problem.

Just a little background on the cores, those are not ferrite powders, but flat loop annealed 1 mil 80%Ni tape wound ones--good for audio.

Best, M

Wow, sounds interesting.  I have a couple MXL603's I've been wanting to put tubes in so this would be interesting...  the usual method is to have the transformer in the PSU box because it won't fit in the thin mic body.  Could this be done with your transformers?

Would also be interested in BV8 type winding for large diaphragm mics....

What will they cost if you can reach the mininum?

I would try a 6.5:1 unit.

Michael

Another great idea, Mark! I'd love to try a couple.

Stewart

I would like a couple (at least).  ;D

Toroidal output seems like one of those things that should have happened ages ago.
In any company large enough to have an accountant, this just can't happen.
"the transformer we have sounds fine, toroidal is too expensive, there's no damand, bla, bla, bla"

Really needs a determined free spirit like Marik to say
"F**k you lot, it's a great idea, I''l do it on my own"

Bet they sound great.

(Off topic, Stewart, I will post results on that Varicoustic soon, sorry,have been swamped at work for weeks)

tommypiper said:

Wow, sounds interesting.  I have a couple MXL603's I've been wanting to put tubes in so this would be interesting...  the usual method is to have the transformer in the PSU box because it won't fit in the thin mic body.  Could this be done with your transformers?

Click to expand...

Hy Tommy,

Yes, the PSU is a usual place for transformers in SDC's... but again, it works only for cathode follower configuration. The cone will allow to use the transformers in the body itself and use the plate follower (which before was used mostly in LDCs). Also, I tried these transformers with FETs with great results. IMO, the SDC's were never given a good chance because of lack of space to put a good transformers.

tommypiper said:

What will they cost if you can reach the mininum?

Click to expand...

With SDC cones (or might be just entire body, which could accept say, MXL603, AKG CK6x series, or any readily available capsules) I will need to talk to the CNC machine shop just down the street (they do most of the work for me in bulks), but to keep the prices down it should be at least 20 pieces. If there is enough interest, I could make the transformer housing in a way that the PCB could be bolted to it right in the middle... or make a body/PCB/Transformer kit...

As for the transformers, the price in singles (1-9) is $159. If there is demand and we can make one type of the transformer (say 6.5:1) in quantities, then 10-19 will be $129, 20-49 $119, and 50+ $109.

I'd think the most popular ratios would be 6.5:1 (BV8) for use with EF86, 6AK5, 5840 and other pentodes in triode connection, as well as 12AU7, etc., and 10:1, for use with 6072/12AY7 and FETs.

ArR said:

I would like a couple (at least).  ;D

Toroidal output seems like one of those things that should have happened ages ago.
In any company large enough to have an accountant, this just can't happen.
"the transformer we have sounds fine, toroidal is too expensive, there's no damand, bla, bla, bla"

Really needs a determined free spirit like Marik to say
"F**k you lot, it's a great idea, I''l do it on my own"

Bet they sound great.

(Off topic, Stewart, I will post results on that Varicoustic soon, sorry,have been swamped at work for weeks)

Click to expand...

Thank you ArR for support! Indeed, one of the reasons they were not used before might be very high cost of core and manufacturing. Another reason is their size. In order to keep the size down (my first prototypes with off the shelves cores had huge 1 5/8" (!!!) diameter) I actually need to order custom size (in order to get the same area they are thicker).  

To get low capacitance the pri winding is divided into 4 sections (that's how it was made in BV8). I use automatic toroidal winders, so even 6 sections would not be a problem (for higher ratios, with higher Pri L). The secondary is center tapped and wound bifilar, so it is completely symmetrical.

Best, M

I'd think the most popular ratios would be 6.5:1 (BV8) for use with EF86, 6AK5, 5840 and other pentodes in triode connection, as well as 12AU7, etc., and 10:1, for use with 6072/12AY7 and FETs.

Click to expand...

I think you'd be right - those would be popular & useful ratios for DIY projects, and I'd be interested in a couple at 6.5:1, especially at the lower prices!

My only other thought was something for cathode follower microphones projects, although you don't see so many of those being built.

S.

Hello.

Marik i could be interested in some of them. Don't know how many (probably 3/4) and which turn ratio for the moment.