Bo Hansen DI layout

[Neil]

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.

 

[Bo Hansen]

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

 

[Soeren_DK]

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

 

[Bo Hansen]

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

 

[Neil]

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?

 

[Bo Hansen]

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

 

[Neil]

Ok, thanks Bo! I read your notes on the web page but since those components weren't mentioned I thought I'd ask to be safe.

 

[joellegros]

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!

 

[ericjazz]

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

 

[[silent:arts]]

Does anyone know dimensions (height) for the ST8456?

yes: 16mm

 

[briomusic]

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 

 

[diyfanatic]

Another one @ thomann 58€  With Haufe trafo

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

 

[ericjazz]

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

 

[[silent:arts]]

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)

 

[mrcase]

thats a good deal on the haufe transformers.
do you have them in stock already?

 

[[silent:arts]]

not in stock, but I'm awaiting them next week.

 

[benlindell]

I'd definitely like to get a pair of those transformers when you get them in.

 

[mrcase]

count me in for 2 please!

 

[[silent:arts]]

guys, I will serve you, but please let us leave this thread to the great DI ...
will post somewhere else once I have the transformers in hand.

 

[neodyms]

hi all !

For every body finished this Project, what's your impressions about the sound, the fidelity ?