Orange 86 Build Thread - no PCBs for sale

[stitch-o]

Squish is experimental and not necessary, but it's up to you.  I would definitely have a switch to bypass the Squish altogether though.

It seems that you have the impedance switch sorted, though I wouldn't bother.
-the gain switch is measured to be pretty close to the correct decibels.
as follows:

46, 43, 40, 37, 34, 31, 28, 25, 22, 19, 16, 10
(the 10 dB mark is much less than the other increments as an safety feature for very high gain sources)

-the lamp should be fine.  but my lamp accounts for current draw, and may be something to consider.  Do you know the lamp Current draw?
500-600mA should be within range. 

C10-C14 are snap caps.  C11 and C12 have an option for leaded caps.

-Other cheaper switches should be fine.

I hope this helps.

The fact that the 'squish' can be switched in and out of circuit is a winner for me.
I like to experiment, so in goes the squish.
The place I get my lamps has .15 and .25A lamps so these will do fine I think.
Cheers for the dB readings! The closer I get to finishing the frontpanel design, the more I want the
rest of the box finished as well.
RE: the impedance switching - I like as many switches to play with as possible.
Could be nice for ribbon mics, right?

I'm sure I'll be back for more tips...fantastic project....

Cheers!

 

[guavatone]

I just caught a mistake on the build doc for the PAD PCB.

basically,

MIC+/- should go to XLR input.

Out +/- goes to the input transformer.

I am reworking the build docs to help a bit more. 

 

[stitch-o]

I had a random thought (to add to my need for more switches):
In the build docs you describe 3 sets of resistor values for different HF rolloffs.
Any thoughts on wiring those to a frontpanel switch?

You all can tell me I've gone too far with the switches...

 

[guavatone]

I had a random thought (to add to my need for more switches):
In the build docs you describe 3 sets of resistor values for different HF rolloffs.
Any thoughts on wiring those to a frontpanel switch?

You all can tell me I've gone too far with the switches...

This is DIY so who am I to say stitch.

3 may be a bit much, but an easy way would be to take R-FB! and C-FB1 off of the main PCB and make a switch that throws a cap in parallel
to change the rolloff value.

 

[jyrki3101]

HI, a couple of weeks ago I also noticed the same mistake on pad pcb wiring-guide, but unfortunately forgot to mention about it.
Only a few hours of wiring left and I should be ready to power up this thing, probably next week after I get back from a 4-day tour....
Regards, jyrki3101
P.S. A complete wiring guide would have helped a lot but I guess I have learned much more figuring things out by myself.

 

[kato]

P.S. A complete wiring guide would have helped a lot but I guess I have learned much more figuring things out by myself.

A complete wiring guide is available. Did you download this?

 

[imo]

Charlie,
Having missed your pwr supply boards, and seeing that currently you don't have plans for another run, do you have any suggestions for an elegant way to get +48 and +24(relay)? I am planning on using a standard transformer(either the Edcor or a spare at 290HV) So i would probably just run the heaters on AC for now. I could probably scab something together for this, but thought it was worth a quick query before i did.
Ian

 

[baadc0de]

It's quite possible that I haven't been following up on this project 100%, but I was under the impression that a new run of the power supply board is in the works, with some tweaks?

 

[guavatone]

New Build Docs uploaded.  I'll try to got to some of these other questions soon.

 

[tommypiper]

What kind of file format is that new build docs?  It opens up as gibberish!   :'(

EDIT:
Ok, after some research and futzing, I was able to open it on a Mac with Stuffit Expander.  (Usually Stuffit opens up everything automatically, but this one was weird...)

Docs look great, thanks!  

 

[Kingston]

works fine here

it's RAR. Not the ideal format if you are on OSX to be honest.

 

[tommypiper]

Not the ideal format if you are on OSX to be honest.

Exactly.  Guys, you'll have to manually open up Stuffit and then try to open the file with it...

 

[MikoKensington]

For Mac users UnRarX works great. 

 

[guavatone]

http://wakaba.c3.cx/s/apps/unarchiver.html

may favorite mac unwrapper.

 

[pacemaker]

Hi Guavatone
i am building a 2 channels with your PSU board,
am i right thinking that the power components
are not needed on the preamp boards ?
regards,
pacemaker

 

[guavatone]

Hi Guavatone
i am building a 2 channels with your PSU board,
am i right thinking that the power components
are not needed on the preamp boards ?
regards,
pacemaker

The power section on the preamp PCB is needed for 290-300 VDC power.  The PSU board is for Relays, DC Filaments and Phantom 48VDC.

i hope this helps.

 

[pacemaker]

Ok thank you,
I also noticed that on the 1.2 bom,
there's no value for C16 but
there is 2 C17 ,
470UF/35V and 470UF/25v,
so is C16 a 470UF cap  ?
Regards,
Pacemaker

 

[guavatone]

I also noticed that on the 1.2 bom,
there's no value for C16 but
there is 2 C17 ,
470UF/35V and 470UF/25v,
so is C16 a 470UF cap  ?

Sorry I missed that.  The schem should show correct value for the PSU PCB
C16=470UF/25V
C17=470UF/35V
-both may be 35V though

Revised BOM files to 1.3.zip

 

[pacemaker]

Hi Charlie,
I noticed other differences between schematic and partlist,
C-FB1 is 6n8 on the BOM, and is 10nF on the schematic,
C-FB2 is 4n7 on the BOM, and is 22nf on the schematic
and on your negative feedback compensation,
C-FB1 is 4n7 /10n /22n or 33nF
C-FB2 is 6n8 /15n /33n or 47nF
Also R5 on the power supply board, is not listed in the BOM,
and is 47R 1W on the schematic

Hope it would help to update the 1.3 files
Regards,
Francois

 

[guavatone]

sorry pacemaker for the confussion.  

When values are in question, please use the BOM values.

The reason C-FB1 and C-FB2 differ  is for personal taste.  These caps control HF shelving for the Negative Feedback.
Some people will like the sound of a 100K rolloff whereas others may prefer 30-50K.  
-Personally, I like 30-60k rolloff.

I am sorry this is not a cookie cutter project, but rather something that will hopefully educate a bit.
IMHO, these values are not very critical, so the good thing is that one can calculate the rolloff they want
with whatever caps they have lying around, but it's best that both rolloff values for the 2 caps are close
to each other or that the lowest gain stage rolloff is less than the second stage rolloff.
 -Just don't change the resistor that is in parallel with the caps.

-The original British preamps had the low stage rolloff at 36.4K and the second stage at 48.2K.
-I believe Revolution used 112K and 160K respectively.

I think the Original designers were very conservative lab coat guys, so really, one could get away with
a higher frequency before oscillation.

Thanks for the heads up on R5.  -this is not necessary but helps to tame current a bit.

I hope this helps

-BOM updated to v 1.4 but no longer in PDF format.