3D "AIR" EQ - "Night EQ" PCB's Complete!

[khstudio]

I forget... didn't I mention the ohms @ the halfway point?

If not, I'll recheck. I think I have it written down.

The more I think about the center detent pots (or ANY pot besides the originals), you may be on to something when it comes to the "REAL" value & the center point... I'm sure some components could be adjusted to compensate but I wouldn't want to do it.

Kevin

 

[peterc]

I remember 40k at the centre point.

Pots are +- 10% tolerance usually so I dont know how much difference it would make. A multiturn pot would be a good idea though.

Peter

 

[khstudio]

OK,
I just set ALL the bands of one channel to the center & got readings between 46k & 48k... 3 out of the 5 were closer to 47k.

So 47k it is @ the mid point.

Kevin

 

[khstudio]

Before I get into anything crazy, what's the best way to test this thing... like for distortion, bad IC's, etc... :?:

Thanks

 

[Purusha]

Nice work Kevin. Where did you say you got those red knobs from? I really like them on your front panel design :thumb:

I think I need to start more colourful designs for my cases :green:

BTW, those are Mnats PSU boards? That's really great as I have a bunch waiting to be used.

 

[Harpo]

Hi Kevin,

congrats :thumb:

easyest way to compare is to plug both units in your patchbay, both set to bypass. (1 ch. nightair/1 ch.3dAir). Feed them with a squarewave signal and scope before and after elcos C1, C14 and C15. This way you also check for faulty Op-amps U4 at pin 1 and 7 and U5 at pin 6, cause these are always in your signal chain. Your described harshness may come from these, if there's something wrong. The filter-caps in the nightair has the cheapest availiable 1uF poly's built in, but in bypass the filter stages are out of circuit.

 

[khstudio]

[quote author="Harpo"]Hi Kevin,

congrats :thumb:

easyest way to compare is to plug both units in your patchbay, both set to bypass. (1 ch. nightair/1 ch.3dAir). Feed them with a squarewave signal and scope before and after elcos C1, C14 and C15. This way you also check for faulty Op-amps U4 at pin 1 and 7 and U5 at pin 6, cause these are always in your signal chain. Your described harshness may come from these, if there's something wrong. The filter-caps in the nightair has the cheapest availiable 1uF poly's built in, but in bypass the filter stages are out of circuit.[/quote]

OK, I will test later today :thumb:

Your saying the Electro's could be the problem & I can see it on the scope. Believe it or not I just FINALLY got a decent tone generator but have never done a squarewave test. I have an old Tektronix 564b scope.

I'm sure this is something I NEED to do for testing a lot of my gear & problems

The filter-caps in the nightair has the cheapest availiable 1uF poly's built in

Really :shock:

We talked about this WAY earlier in the thread but no one knew what "Type or Brand" they are... do you?

The more I listened to the REAL one last nite it DID work - it was just harsh & I felt it had a "Headroom" issue too.

Thanks man

 

[khstudio]

[quote author="Purusha"]Nice work Kevin. Where did you say you got those red knobs from? I really like them on your front panel design :thumb:

I think I need to start more colourful designs for my cases :green:

BTW, those are Mnats PSU boards? That's really great as I have a bunch waiting to be used.[/quote]

Radioshack knobs & MNATs PSU.

 

[Bauman]

Great stuff Kevin!!! :thumb:

 

[peterc]

Quick pic of the half done prototype

I'll go with lin pots for testing, anyone spoken to Omeg yet?

Peter

 

[khstudio]

KILLER :thumb:

I'm very happy that all my hard work did not go waisted. I hoped but didn't think it would take off this fast. Thanks to Peter for believing in my drawings of a unit he can't see :razz: AND for all his hard work too.

I'll go with lin pots for testing,

I think I tried that & it was TOO sensitive... Hooking up audio Tapers BACKWARDS & using them BACKWARDS works pretty good for testing.

 

[gar381]

WOW...Really nice looking stuff Kevin! :thumb:
I need to put some of your "AIR"s on my short DIY list.
Maybe after some 553s. :?

GARY

 

[Godders]

[quote author="peterc"].... anyone spoken to Omeg yet?

Peter[/quote]They can do 470K Rev Audio with center detent, they didn't offer up any pricing though.

Which type do we want?

http://www.omeg.co.uk/products.htm

Cheers

Nick

 

[peterc]

What about the BR16ECO, that is the 16mm ECO type with a PCB bracket.

They should be about a quid each.

I would be in for 10 of them.

Thanks
Peter

 

[sonicwarrior]

Will someone produce a batch of these PCBs?

If so I would also take the pots for 2 PCBs.
I'm a little confused as the original schematic listed 6 470 k pots but the clones seem to be a bit different. :?

Man, if only Cosmo would be as nice as Omeg. *dreaming*

 

[Godders]

Rev log is the same as Rev audio right?

And there are several options for length of spindle etc. on the enquiry form. If someone wants to take a look and tell me which is the correct one (or whther it matters):

http://www.omeg.co.uk/bre16brc.htm

I'm more than happy to get a group order together but obviously I don't want to buy a load of the wrong pot. :?

 

[sonicwarrior]

[quote author="Godders"]Rev log is the same as Rev audio right?[/quote]

Yes, it's the same as "Law C":

 

[Godders]

Thanks Joachim. :thumb:

Cheers

Nick

 

[khstudio]

[quote author="sonicwarrior"]Will someone produce a batch of these PCBs?

If so I would also take the pots for 2 PCBs.
I'm a little confused as the original schematic listed 6 470 k pots but the clones seem to be a bit different. :?

Man, if only Cosmo would be as nice as Omeg. *dreaming*[/quote]

If you follow the thread you'd see that Peter is working on it :wink:

I made the schematic & I don't recall listing 470k for the pots :roll:

They are 500k RA... the original ERROR was 5k but that was WRONG & FIXED. (or addressed)

 

[sonicwarrior]

[quote author="khstudio"]
If you follow the thread you'd see that Peter is working on it :wink:
[/quote]

I'm sorry, here are so many big threads and I don't have the time to read all information and let them stay in my brain.
That's the main problem with all the big threads here.

If it helps I can post the project information on my sdiy.de site (which still has no root page) or the groupdiy.de site which I haven't used by now.

[quote author="khstudio"]I made the schematic & I don't recall listing 470k for the pots :roll:

They are 500k RA... [/quote]

470k or 500k is a big difference. :wink:

But anyway I just took the 470K from Godders posting. :razz: