110 Style

[JustinS]

Hey Key,

No have not yet made a PCB... wanted to find more about Peter's PCB layout before I ventured there... will still maybe do my own layout(it would be my first!), there are a few other things I might want to implement, but I thought I could learn from what Peter has done... I like having a trim fader... maybe 10b would be better... I'm still not quite sure where Peter has hooked his up :?

Justin

 

[peterc]

Here are the RS part numbers to built that switch :

665-837 1 x 12 way switch + mechanism
352-294 extra 1 x 12 way wafer
352-339 spacers (you need 'em)

Peter

 

[omeiko]

Hello Kev.

I've got the files ready for the 430-clone (the amp-section). Can I send them to you? The folder is about 1Mb in size.
Sorry for the delay but I've been very busy lately.

cheers,

Okko

 

[Kev]

YEP
send away ... anytime

diy, diy
happy, happy
DIY

 

[omeiko]

Ok. Here it is: http://www.diyfactory.com/projects/diy110/diy110.htm

Thanks for Kev for hosting this :thumb: .

This is my version of the f-rite i.s.a 1.1.0 preamp.
It's a great sounding unit but it uses couple of quite expensive transformers.
I think it's well worth building though.
Here is the little description of the project that can be found on the site:


This is a preamp based on the amp-section of the F_rite I.S.A 430 ( which, I believe, is the same as in the I.S.A 110 ).
I changed the output transistor pair to the one found on the red series because they were easier to find. The output sections in these are nearly identical so the sub is nothing to be worried about.
I've done a pair of these and the layout seems to work right but if you build this you should check it against the original schematic.

I don't have the original to compare but the preamp sounds great and the sound is very smooth and sophisticated.
I used the Elna Starget and Panasonic FC caps and I tend to like the Stargets better.

The toroidal output transformer (carnhill vt30408)
is critical in this design since it has a tertiary feedback winding and most of the character of this pre comes from this trafo.
I had no trouble getting them directly from Carnhill but they were quite expensive (about 70 euros each).

The gain switch is a two deck 11-position.

Note that the board doesn't have mounting holes so you have to use some creativity to mount them in the box.
It doesn't have any phantom or phase switching either so you'll have to figure them out by yourself.

I made this project a year and a half ago so I'm not sure that I have remembered everything
so if you decide to build this project please check it against the original schematic.

Cheers!

-Okko

 

[Bauman]

Great stuff! Thanks!!!!

 

[Guest]

Wow, great stuff! Looks like Kevin at K and K and Carnhill are going to get some more of my money. I don't know if I have enough time to build all of this stuff.

Cheers,

elco

 

[Guest]

Ok, how about the EQ section? Jakob, what is so difficult about the F-rite EQ as oppossed to the Calrec? Aren't they both state variable? Same Voodoo right?

Cheers,

elco

 

[frede]

I am really interested in building this preamp. I have used a I**-110 recently and it sounded very nice.

What kind of powersupply will fit 2-4 of these pre's best, including 48v for phantom?

Okko writes at the DIYfactory page that the circuit doesn't have any phantom. As far as I understand the pcb is equipped with phantom and just needs 48v along with the +/-15 volt supply. Am I understanding this correct?

What about the EQ section. Is this impossible to DIY?

 

[omeiko]

Hello frede!

What kind of powersupply will fit 2-4 of these pre's best, including 48v for phantom?

I've used this psu from Peters C's site succesfully in many preamp projects.
http://1176neve.tripod.com/id11.html. It has +/-15V and 48v. It should be able to power dozen of these with no problem.

The board feeds phantom to the input pins 1 and 2.
It's a little complicated that all the pins of the input tx are accesible but this way you can make a input impedance switch or some other fancy stuff.
If you want to use it normally you just connect pin1 to pin4 and pin 2 to pin3 and feed the signal to 1 and 2.
The phantom switch must be between the psu and the mic pre card power input.

What about the EQ section. Is this impossible to DIY?

Everything is possible :wink: . They dont use any fancy parts as far as I know but it would be much more involved project than just the mic pre cards.
I've planned of makin a couple of these eqs but havent had time. I've got the PCBs ready but I have way too many projects going on. Maybe someday..

Here are some (bad) pics of my box. It's not compeletely finished yet (note the missing phantom and pad switches).

 

[frede]

Hello Okko!

Wow! :shock: Looks really cool! Have you made the frontpanel yourself?

I will use the psu you suggested for the preamps. Thanks for the help.

It sounds very interesting with the impedance switch option. I am still a kind of a newbie to this, so I can't figure out how to made this, and what selection of impedances it will get. Do you have any scematic for this?

What kind/brand of switches are you using for the gain control? ELMA's?

Does anyone know if it's possible to buy the red and grey knobs used on the Vintagedesign stuff? (http://www.vintagedesign.halmstad.net/vd_english.htm) The white pushbuttons are nice too.

Thanks a lot all this, :thumb: :thumb: :guinness:
Frede

 

[omeiko]

The frontpanel is made on a printed inkjet transparency film. The picture is printed as a mirror image and then clued to the frontpanel the colorside down. I learned since that the film will peels of pretty easily so now if I use this method I print the picture oversized and turn the excess material around the corners.

It sounds very interesting with the impedance switch option. I am still a kind of a newbie to this, so I can't figure out how to made this, and what selection of impedances it will get. Do you have any scematic for this?

Look at the ll1538 datasheet. http://www.lundahl.se/pdfs/datash/1538_8xl.pdf
It shows how you can wire the primary to 1:2,5 or 1:5. It should be pretty easy to make the ratios switchable with a dual on/on-switch. though I don't know how usefull it would be.

What kind/brand of switches are you using for the gain control? ELMA's?

Yes. I used an Elma switch there. We have one very cheap source for elmas here in Finland. I think Jaakko knows what I'm talking about...

cheers!


-Okko