Anyone built a 1073 in a pedal?

[Esppse]

I'd like to get a stereo pair of 1073s in my setup. I was curious if someone built anything like the Broughton Studio One or JHS Colour Box. Both are 1073 style preamps. I plan to be running line level signals into then too.

I've built a 500 series 1073 from a kit, but I'd like to see if there may be a layout similar for more of a pedal style.

Thanks

[GGBB]

Both of those pedals are BIG. Saw a color box firsthand recently and was surprised at how big it was in person - bigger than anything I would consider pedal-sized by modern standards. I think some 500 series boards would probably fit in either of those boxes - have no idea about the 1073 specifically of course.

[ilcaccillo]

Wow, those pedals are really cool, always loved the sound the Fuzz you get when you connect a guitar straight into a mic preamp (no DI in between)

Instrument Level into Mic level

I use that a lot with bass in recording.

I built quite a few Neve preamps already, Im pretty sure that none of those pedals use the straight 1073 topology, they are probably base on some parts of the circuit. Probaby the discrite transistor amplifiers.

The Neve 1073 has Input transformer, a big output transformer (similar to a power transformer) and uses inductors for the EQ.

The Mic Amplifier stage on the Neve 1073 is called the Neve 1290.
It can also amplify up to 80dbs


JHS seem to have used a Lundhall input transformer.
There's no Output transformer on the JHS or inductors.

Well I would like to design something similar for guitar.
If anyone is interested in doing and developing a project like this please let me know

[merlinb]

Another thread jack, sorry! The 1073 occasionally crops up in pedal forums, and I know the original 1073 schematics are pretty confusing so I drew up a poor man's 1073 preamp stage which I am posting here for reference.
Note this is just the preamp section. A real 1073 uses a complicated multi-way switch for 5dB gain steps, which I have simplified with pots. The preamp would then be followed by EQ and an output amp in a real 1073. You can of course bolt on whatever EQ circuit you like, which is what the Colour Box does.

[fryingpan]

Another thread jack, sorry! The 1073 occasionally crops up in pedal forums, and I know the original 1073 schematics are pretty confusing so I drew up a poor man's 1073 preamp stage which I am posting here for reference.
Note this is just the preamp section. A real 1073 uses a complicated multi-way switch for 5dB gain steps, which I have simplified with pots. The preamp would then be followed by EQ and an output amp in a real 1073. You can of course bolt on whatever EQ circuit you like, which is what the Colour Box does.

I thought the 1073 was FET-based?

[merlinb]

I thought the 1073 was FET-based?

No, you're probably thinking of something else.

[Transistor-Transistor]

Hey isn't JHS's Crayon just that 1073 preamp?

[merlinb]

Hey isn't JHS's Crayon just that 1073 preamp?

Hmm yeah it does look like it probably is, sans transformers.

[Jarno]

Know that on the OSHPark shared projects there are the Neve BA283 output and preamp boards that you can order or download the gerbers for.
I ordered them and will use them for a Neve-esque preamp without tone controls (but with both input and output transformers).
Need to do the wiring and testing still, but the layout of the boards looks good, seems to use the component designators from the original Neve service manuals.

[merlinb]

Know that on the OSHPark shared projects there are the Neve BA283 output and preamp boards that you can order or download the gerbers for.
I ordered them and will use them for a Neve-esque preamp without tone controls (but with both input and output transformers).

Nice project! What you're building is basically a Neve 1272, a highly coveted bus amp.

[Jarno]

Yeah, also not even a complete one, hardwired FET input into input TX, only a single amplifier board (the second one is only used for a few of the highest gain settings which I do not expect to need) into the output amp, into output TX.
So, barebones, I suppose

[Tatry9]

Know that on the OSHPark shared projects there are the Neve BA283 output and preamp boards that you can order or download the gerbers for.
I ordered them and will use them for a Neve-esque preamp without tone controls (but with both input and output transformers).

Nice project! What you're building is basically a Neve 1272, a highly coveted bus amp.

Those BA283 boards should give you that classic Neve vibe. Let us know how the wiring and testing go would love to hear how it turns out

[merlinb]

Be sure to use tantalums for the input and output caps if you want the true Neve flavour 

[amz-fx]

JHS seem to have used a Lundhall input transformer.
There's no Output transformer on the JHS or inductors.

From the pcb shots, it is the Lundahl LL1578

https://app.box.com/shared/static/bjqgolic39ccga6y21i7.jpeg

regards, Jack

[Jarno]

Be sure to use tantalums for the input and output caps if you want the true Neve flavour 

Did those Neve units use tantalum, hmmmm, was going to use something more modern myself, but might reconsider that.
Not a fan of tantalum ever since I had one explode in a PSU, that smell really lingers....

[merlinb]

Did those Neve units use tantalum

Yes, and they do contribute some measurable LF distortion. But for guitar honestly use what you like, I was being a little facetious. People on cork-sniffing forums like to copy every minute detail!

[Chillums]

Just a FYI about tantalum caps/metal.  I don't use them as I learned early on that it's a conflict mineral...

Tantalum is considered a "conflict mineral," meaning it is a metal that is often mined in regions with ongoing conflict where the trade of the mineral can directly fund armed groups, and is commonly sourced from the Democratic Republic of Congo (DRC); alongside tin, tungsten, and gold, it is one of the key metals classified as a conflict mineral, often referred to as "3TG."

Source of funding for conflict:
When mined in conflict-affected regions, the sale of tantalum can provide significant financial support to armed groups, fueling violence and human rights abuses.

Regulation and due diligence:
Companies are increasingly required to implement due diligence practices to ensure their supply chains are free from conflict minerals, including tantalum, by verifying the origin of the metal and ensuring it is sourced responsibly.

Not to mention...

Environmental concerns:
Tantalum mining can disrupt the surrounding ecosystem.
The tailings from tantalum mining may contain thorium and uranium, making them potentially radioactive.
Tantalum mining in areas like the DRC and Rwanda has been linked to conflict minerals.

[Jarno]

Yes, Tantalum, as well as Tungsten, Tin and Gold (and I believe Cobalt also used to be classified as such?) are conflict minerals. POTENTIALLY financing armed conflict.

And literally all mining is bad, I visited Ecuador, where Bauxite and Copper are mined, and that doesn't look great, even though it might not be radioactive, it doesn't do wonders for the environment. Even for something as stupid as coal whole villages in Germany are destroyed.
Nearly always, mining rights are acquired using lobbying, bribing. Or by selling incredibly expensive infrastructure to countries that cannot afford it ("Confessions of an Economic Hitman").

The important thing is to limit use, and to build stuff that lasts. In my mind at least, but yes if not expressly "needed" don't use tantalum.

[zbt]

Inside The Neve BA283

Manual PDF

maybe it can be divided into

B284A Microphone Preamp
B283A Microphone and Channel Preamp
B284B Hi and Lo Preamp
B284C Presence & High Pass
B283L Line Amp

Stack
B284A -> B283A -> B284B -> B284C -> B283L

1. The challenge is Inductors and Transformers, what if they are made into IOTL
(Input Output TransformerLess)
2. Fixed Low frequency for B284B Hi Lo Preamp, just for guitar
3. Make alternative B182 circuit, do not use an inductor
4. For Line Amp, replace the transformer with a constant current source,
   and uses a capacitor coupling
5. Recalculate the circuit for 9V, and just use the gain pot on pin

just a thought

[amptramp]

I hate to see audio transformers used for audio signals.  You can use a linear optoisolator like this:



or use a modulate / demodulated signal from audio to AM or FM carrier then demodulate it to baseband audio signal again.  The Unitrode UC1901 was designed for isolated feedback for power inverters but it can do the job for low gain circuits.  For better fidelity, a discrete audio stage may be preferred.  It can be seen here:

https://www.ti.com/lit/an/slua124/slua124.pdf?ts=1740662393614&ref_url=https%253A%252F%252Fwww.google.com%252F

on page 311of the manual (page 322 of the download).

This is not as much of a design complication as it may appear because you still need drivers for a transformer.