REDDI DI

[CJ]

this thing was designed to work with the pot on the secondary, which will damp out the hi end bump, if you use a transformer with a flat response, then the pot rolls off too much hi end,

i wind the secondaries with the start on the left and the finish on the right,

then rotate the bobbin 180 and start your primaries on the left, finish on the right,

 

[MicDaddy]

Flipping bobbin would change phase if polarity was not swapped to account for the direction change?  Equivalent of flipping motor/arbor direction?  Grasping phase/polarity vs direction wire is actually passing through the windows is getting easier to visualize but not second nature quite yet. 

video of process
https://www.youtube.com/watch?v=rAbH6l9j0Ig

 

[CJ]

where did you get the Corn Huskers decal?  ;D

 

[MicDaddy]

Fear of entering the smoking zone has kept high voltage from the primary.

I've applied some ~15VDC (was like 17mA) across the primary which makes a sweet electromagnet and no smoke. 

These are pretty flat from like 10Hz to beyond 30kHz.  A small dip 1dBV down ~14kHz and fairly wide bandwidth of like 500Hz.  So I can still say 20-20kHz +0/-1?  8)

Maybe I try to not start a fire tonight... worst case catastrophic failure what's to be expected?  Small fire?  Tripped breaker?

 

[MicDaddy]

REDDI PSU schematic;

39k after rectifier, this is to make UL happy?

I'd like to implement a capacitor drain + LED indicator, like the MK47.  Thoughts on approaching this?

If I omit the 39k, and then add say ~8.5k shunt in series with LED after the final cap?  Think that will work?  Of course, I think this then nearly doubles the current demand on the B+ rail correct?

 

[buildafriend]

Flipping bobbin would change phase if polarity was not swapped to account for the direction change?  Equivalent of flipping motor/arbor direction?  Grasping phase/polarity vs direction wire is actually passing through the windows is getting easier to visualize but not second nature quite yet. 

video of process
https://www.youtube.com/watch?v=rAbH6l9j0Ig

Sup dude!? Wicked setup (I live in Austin but talk like im from Boston?).

Are you making these for personal use or are you trying to sell them?

 

[MicDaddy]

Sup dude!? Wicked setup (I live in Austin but talk like im from Boston?).

Are you making these for personal use or are you trying to sell them?

Trying to get this down and see what path it leads me down.  I want to be able to whip up a circuit, and spin the copper to the circuit.  In no position to offer these for sale.  CJ has a feeler in the black-market that has caught on like wildfire.

Any thoughts on a PSU LED?

 

[pvision]

8) sweet, guess what I'm doing tonight.  \m/  Split bobbin party with the kiddos.  I had my two oldest in the shop last night (6 & 8yrs ).  They say you only know as much as you can teach so we were winding coils, reading wall AC voltages and trying to get a grasp on what exactly are these things these transformers, the concept of step up step down voltages in wall warts etc.  The most fun for them was to watch the machine actually wind at 2000RPM.

Such a great idea to have the kids doing it. There's lots to learn - mathematical ratios, basic electrical theory, transformers, AC vs DC and relating physical things to concepts

Nothing explains ratios better than transformer windings and measuring voltages in & out

Nick Froome

 

[tonedude]

Hi, i am about to build a REDDI and have to ask if the level pot really is doing what it's supposed to do, dampen the output about 16dB, and not, as mine do, go from full blast to zip, zero, zilch,,,,  I'm pretty sure I did hook it up the right way.

I's it really confirmed that the level pot works as it should when implemented per instructions in this thread?

 

[tonedude]

Pot wire - orange and black. They go to 300R resistors that connect with TR secondary.

It sure looks that its right. Ok, have to fiddle with it some more then...

 

[CJ]

you could put a small resistor, say 100 ohms, under the pot if you do not want it to go to zero,

and if you want a little more gain you could use a 2K POT,

and you only need one cathode resistor and cap,

 

[CJ]

here is a schematic with voltages that you should see with your output transformer>

http://groupdiy.com/index.php?topic=61139.0

 

[tonedude]

you could put a small resistor, say 100 ohms, under the pot if you do not want it to go to zero,

and if you want a little more gain you could use a 2K POT,

After loking at the schematic I thought  it would be kind of logical to assume that the pot will short the transformer windings, and therfore make it go silent, when turning the pot down, and it sure did so in reality.... I'll try messing with a resistor in line with the pot.

Thank you CJ!

 

[CJ]

hey, no problem.

just got back from a show in Vegas, used the DI, trend is to keep the stage sound down, ear buds, small amp, DI, plenty of level to drive that snake, get me?

 

[tonedude]

Using "trial and error" I found 56 ohm in line with the pot to be just right, if a 16dB range on the pot is what you are after.

And, buy the way, this DI with CJ's OT sounds marvellous!

 

[kambo]

couple of connection questions for best noise performance etc...
using CJ's trx

• CJ 's trx -  blue cable shielded  ?
• let B+ (red) hanging (away from audio)  ?
• twist grn/blk output cables (pot) ?
• connect 2x300r output resistors close to output XLR, or close to pot ?

 

[CJ]

are you getting some humm?  try sanding the mounting tabs down to bare metal so the cire gets grounded,

this is a tricky box to get quiet, pwr trans has to be at the other end of the audio, a toroid PT can help,
did you add the ground lift? also, make sure that the DI is plugged into the same wall outlet as whatever you are feeding it to,

i thought about adding some cu shields to the OPT, but i believe that the hum is not being induced into the transformer, but into the input circuit of the 6N1P, which is down in the 50-100 mv range,

 

[tonedude]

Twisting/rotating those output-transformers  i relation to PT makes a big difference (as in moving a guitar or bass  with passive pickups around in a room to avoid humm...).

Another one that made a big diference, a sheilded input wire with the sheild connected to one end only, the input jack side. And the input jack ground connected to starground. (I have used isolated tele jacks that don't ground to the case).

Also, a good starground arrangement is nice to have.

In my mono build the above was enough to drop humm and noise down another 20dB or so, to get it really quiet.

In my stereo build i had to mount the PT outside in a separate box to reduce humm to the same level as my mono build, mounting the PT on the outside, made the full "gain" noise / humm as low as - 120db... It's one of the quietest pieces of equipment I have, period.

 

[ruffrecords]

Twisting/rotating those output-transformers  i relation to PT makes a big difference (as in moving a guitar or bass  with passive pickups around in a room to avoid humm...).

That looks like a Hammond case to me in which case the base and top are steel. You often get a lot of trouble with EI transformers bolted to a steel chassis. The chassis acts like a magnetic conductor between the two. You can help this a lot by spacing the transformers off the steel chassis using an aluminium plate. Better still, replace the mains transformer with a toroid type.

Cheers

Ian

 

[tonedude]

PT is a toroid. And yes it's aHammond case, but not one with steel top and bottom, it's aluminum (very easy to drill in... ).

It's this case:
http://www2.mouser.com/ProductDetail/Hammond-Manufacturing/1402HV/?qs=3GbUB62Nf7c%2f8JwnWNkyQA==