Bo Hansen DI layout

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llanafreak44 said:
So which Tranny are you Americans using? All the recommended ones are European companies.

Good question! I'm planning on a Lundahl LL1538 on one, but I'm undecided on the other.

Does anyone have a good suggestion to complement the LL1538? Something a little different sound-wise.
 
I have now recieve a couple of the first batch of the real final pc-cards, and i will give a big compliment to Soren, Torben and Gustav for a great work on this pc-cards, they are very nice and of first class.

About transformers.

You can use all brands and types, if they are microphon transformers, and if they have a primary on 150 or 200 ohms and have a ratio around 1:5 to 1:10, and of course you must connect them backwards in my DI-circuit.

Higher ratio, (10:1) gives more loss from instrument input to balanced output.
The optimal loss for a active DI-box are around -15dB, to match a console microphone input best, so for a 200 ohms "primary" a ratio around 5:1 will fit best, but up to 7:1 can be ok.
But be sure that you configurate primary and secondary windings right, because some transformer can have a lot of impedance/ratio combinations.

There ar a lot of brands of US made transformers as Sescom, Chrimson, Pico, Microtran, Hammond, and many others.

With advantage can older types of "matching" transformers be use in my DI-circuit, like brands as UTC, Freed, Stancor, Altec/Peerless, Triad, Thordarson, Kenyon, Dukane, and many others US made brands.

But watch up for "microphone to grides" types, they have to high ratio for this application.

--Bo
 
Hi Bo.

Can I use other transistors instead of the BC550C and the BC560C?

I have a lot of:

BC328
BC338
BC547B
BC557B


Cheers
Soren
 
Soren,

You can use near all small signal general purpose transistors, that have Vceo 30 volt as minimum, hFE from 200 and up, and fT from 100 mHz and up.

I use BC550-C and BC560-C because this was very easy to get around the world for a couple of years ago, and with right manufactures they was very good  genaral purpose low noise audio transistors.

The pc-card are done for transistors that have TO-92 with pin configuration like a old TO-18 in metal can as BC109.
Here are some other transistor types that direct fit on the pc-card. (not need to twist any legs)

BC550=NPN
BC560=PNP

NPN: BC550, BC549,  BC546, BC547, BC548, all B or C
PNP: BC560, BC559,  BC556, BC557, BC558, all B or C

Here are some older TO-18 transistors in metal can, that also fit direct in the holes.
NPN: BC109, BC108 B or C
PNP: BC179, BC178, BC177 B or C

Then you have hundreds other NPN and PNP transistor, but maybee you must twist the legs to fit in right holes on the pc-card, and you must be 100% sure that you know the transistor pin-out.

Here is some well known NPN and PNP pair that you often can see work together in various audio gear around the years.
As I say before, watch out with pin-out.

NPN: 2SC2240,  PNP: 2SA970 GR or BL (the best pair of all transistors)
NPN: 2SC1815,  PNP: 2SA1015 GR or BL

NPN: BC184,  PNP: BC214 B or C
NPN: BC182,  PNP: BC216 B or C
NPN: BC414,  PNP: BC416 B or C

NPN: 2N4401,  PNP: 2N4403
NPN: 2N4124,  PNP: 2N4126
NPN: 2N5210 or 2N5088,  PNP: 2N5087
NPN: 2N3707,  PNP: 2N3702
NPN: MPSA18, PNP: ------
Of course you can mix all NPN and PNP in a combination.

--Bo
 
I started building mine, but have two questions-

Bo's schematic on his website calls for a .047 uF cap between XLR pin 1 and Monitor Amp Out (-) but on the circuit board it's labelled .1 uf.

Also, on the schematic right beside the .047 uF capacitor there's a 47 ohm resistor, but on the circuit board it's 100 ohm (right below the two 1N4004 diodes).

Which one is right, or can you use either one?
 
Neil,

I have done some value correction the last years, but I have not change the schematic yet.
(new tech page with better info will be displayed soon)

Here are all change I have done:

two 470K to 100K
1uF to 10uF
47 ohm to 100 ohm
0,047uF to 0.1uF

So the component value on the pc-bord are absolute right.

--Bo
 
Anyone know if there is a US distributor for the Haufe ST8456?  Went to their website, but it's all in german (someone mentioned I think).  I will probably build one with Lundahl 1538 first, but would eventually like to try out the Haufe. 

I came up with a layout with a friend last night, but I think I might try this one since it's been tested.  Also, I think I'm going to use a Hammond 1590CGY to enclose it. 

Thanks Bo and everyone who helped make this project possible!
 
Hello,
Does anyone know dimensions (height) for the ST8456? Need to choose the right case (I'm thinking of this: http://www.thomann.de/fr/millenium_die_dibox_passiv.htm, but height can be insufficient...).
Btw, if french guys are ok for a Haufe group buy, then pm me.
Thanks to Bo and Soren for this great project.
Best regards.
Eric
 
ericjazz said:
Does anyone know dimensions (height) for the ST8456? Need to choose the right case (I'm thinking of this: http://www.thomann.de/fr/millenium_die_dibox_passiv.htm, but height can be insufficient...).
wow: case, connectors and two switches for €10 - pretty cool  :D
 
Another one @ thomann 58€  With Haufe trafo :eek:

Millenium DI-Pro - professional passive DI box - Haufe transformer, XLR/jack in, XLR/jack link, XLR/jack out (Haufe transformer), ground lift switch.

http://www.thomann.de/fr/millenium_dipro.htm
 
Thanks for the answers. Millenium DI-Pro is interesting.... I wonder what type is this Haufe transformer.
For your information, I received pricing for 4*ST8456 : 217,55EUR incl shipping to France...
Best regards.
Eric
 
FYI

I will receive some Haufe ST8456 in the next two weeks.
since I ordered a larger batch I can let them go at
EUR 28,30 each + shipping + 19% VAT (if applicable)
 
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