REDDI DI

[abbey road d enfer]

I don't know a lot about how to done this measurements fully by the rules. So I just send signal from DA > reamp box to get guitar level/impedance signal > tube DI > AD > Blue Cat Freq Analizer> my results.

  Are you sure of the frequency response of the reamp box? What D/A converter are you using? Many accept their outputs to be connected to unbalanced inputs. That would allow to bypass the reamp box.

Let me know how I could done THD mesurements and I'll made it.

As I mentioned, download RMAA and run it (after reading the manual). Set the oscillator signal to about -15dBu.

 

[dirty1_1garry]

RMAA only for PC... Lost my Paralell Desktop licence

 

[raymancem]

What is the 25 watt output transformer windings? Do you have exactly the schema and the original? Thank you.

 

[dirty1_1garry]

What is the 25 watt output transformer windings? Do you have exactly the schema and the original? Thank you.

https://www.edcorusa.com/p/475/cxse25-600-5k

 

[dirty1_1garry]

Here is my final elements position of my tube di with big 25W output transformer.
But it became pretty close to power transformer and I've got a hum.
I've rotate pwr transformer around the case and get that if I place it like on image it gives much less of hum.
But - bad magic - when I'm closing the case with top cover hum becomes more for about 15dB!!

 

[flaheu]

I see that your assembly is very compact and also that your chassis is made of steel.
Maybe, when you put the cover back you "close" the loop with the base and then maybe the magnetic fields surround your output TX and make it hum.
Try to close your box with an aluminium lid or reassemble everything in a bigger box.
You can also try to rotate the toroidal poxer TX,  the place where the toroidal TX leak the most is where the wires go out of it.

by the way great job it sounds really cool !!!

 

[abbey road d enfer]

Here is my final elements position of my tube di with big 25W output transformer.
But it became pretty close to power transformer and I've got a hum.
I've rotate pwr transformer around the case and get that if I place it like on image it gives much less of hum.
But - bad magic - when I'm closing the case with top cover hum becomes more for about 15dB!!

The flux lines from the toroid are directed right through the OT. It should be placed on one of the other sides or on the bottom plate. You will need to orient it for minimum hum with the lid on. You may try to install some shieding, like a steel plate. Anyway, you'll have to proceed by trial and error.

 

[Hank Dussen]

I asked Phyllis Weston of Edcor if they could make a GXSE15-600-5K.
That would be the 15 watt version of the CXSE25-600-5K, the big 25 watt output transformer Gary used in his build.
This seems to be about the size of the original REDDI transformer.
It would be $37.96 each plus a one time design and setup charge of $40.00. Lead time is 8 weeks on new designs.
Anyone in for one these?
I'm not gonna do a group buy since I'm not into the hassle but maybe It's interesting to order a few at once and thus split the setup charge?

Pieter

 

[dirty1_1garry]

I asked Phyllis Weston of Edcor if they could make a GXSE15-600-5K.
That would be the 15 watt version of the CXSE25-600-5K, the big 25 watt output transformer Gary used in his build.
This seems to be about the size of the original REDDI transformer.
It would be $37.96 each plus a one time design and setup charge of $40.00. Lead time is 8 weeks on new designs.
Anyone in for one these?
I'm not gonna do a group buy since I'm not into the hassle but maybe It's interesting to order a few at once and thus split the setup charge?

Pieter

That's interesting for me. What specs would be in 15W model?
Send a PM.

 

[Hank Dussen]

I think it would be about this specs:
http://www.edcorusa.com/p/542/gxse15-16-5k

It says the frequency response is 40~18K Hz., <1dBu
On paper that are the same specs as the 5 watt version but I think it will be much closer to the sound of the 25 watt version since it's 15 watt.
But I can only guess. The size seems to be only slightly smaller then the REDDI transformer.
The lams are 100 EI as opposed to 75 EI in the 5 watt version.
I feel a 15 watt transformer should do for a tube DI. And this one fits in the case I had in mind and the 25 watt version doesn't.
I'm not an expert but am willing to take the chance...

 

[drivebystudios]

;D

geeeezzzz.....there really is minimal components

 

[CJ]

winding a coil  for 100 EI lams,

8K:600

split bobbin for 1/4 C-d,

Sec DCR seems high on the original at 132 ohms,

this guy will be more like 35 ohms, which is more typical of a 600 ohm winding,

do not know if dirty harry got his ohms right unless they were trying to get the atten pot to work better against a higher sec DCR, 

 

[raymancem]

12au7 Mode.....I want to run this application for 12au7 lamp..

Transformer Enductance  , Resistance What is the value?

 

[raymancem]

CXSE25-600-5K DC Coil Resistances Primer + Seconder =  how many ohms ?

 

[CJ]

here is a schematic of the tube circuit and pwr supply,
this version has no 1M gain pot,

LM 317 values were re-calculated and have not been  proven yet in the real circuit,

so i put question marks by them until further notice, let me know if you have values that work good and i can pencil them in,

voltages and xfmr info has also been added thanks to Dirty Larry, 

Sec DCR is probably right, they made it higher than a standard 600 ohm xfmr probably to get the pot to work better, it has an easier time dragging down a higher DCR as the voltage/current source will not be as stiff as say, a 11 ohm sec,

also, more sec DCR means smaller wire which means better high end response as capacitance will be less due to less copper acting as a plate of a capacitor,
if you go back and look at the xfmr pics, you can see a lot of space left on the bobbin, which also indicates smaller sec wire

there were some AC voltage measurements taken by Larry from pins 1 to 2 and 1 to 3 o the output XLR, but these were not included as the transformer would isolate these signals and therefore they are of questionable character,

note that this amp "plays out of phase" like a Marshall but we can flip the polarity back to in phase with the output transformer, this can possibly be important if recording with two signals,

oh, and Merry Christmas! 

 

[raymancem]

Vr1 Potentiometer Out output short circuit .........
3,67 :1 Ohm - Kohm ?
Wire diameter , Number of laps , Hair section Can I learn these values

 

[CJ]

we should probably mark "front" or "back" on the pot, good catch,

3.67:1 is the turns ratio,

 

[mutterd]

note that this amp "plays out of phase" like a Marshall but we can flip the polarity back to in phase with the output transformer, this can possibly be important if recording with two signals,

oh, and Merry Christmas! 

this is a great project...

a phase reverse is important for sure, and ground lift...

any of you guys that have completed these - did you add such? I know the REDDI has at least a ground lift...

going to putter around with this today - thanks.
Tim

 

[CJ]

you can simply swap pins 2 and 3 on the XLR to get the phase back to normal,

yes people have built this circuit, there are some sound files a few pages back,

 

[CJ]

spruced up the schemo a bit,

made an arbitrary (always wanted to use that word!) decision on some part designators,

added an optional gnd lfit and a parallel output jack,

let me know i you see any misteaks,