canidoit

Are any DIY designers contemplating this build or is it not feasible or legally allowed?

I have not heard anyone attempt the API eq, but I have read heaps on API preamps, Neve pres and eq, etc.

I think this would be a wanted killer DIY kit or clone if it became available.
iva dunit formerly known as canidoit


bruno2000

Are any DIY designers contemplating this build or is it not feasible or legally allowed?

I have not heard anyone attempt the API eq, but I have read heaps on API preamps, Neve pres and eq, etc.

I think this would be a wanted killer DIY kit or clone if it became available.

Maybe.............
But the switching is a b**ch.
Best,
Bruno2000

okgb

the cost of the switches for one ,
nvermind wiring them , wonder how they're done
on new 550's ?  but perhaps

there's a brave superhero who can't resist a Challenge ?
GKB Audio / Greg Boboski

QUEEF BAG

now they use grayhills that solder right to the circuit board

no dickin' around with wires.

i wouldn't wanna take it on though...

jsteiger

I have been studying the 550, 550a, 550a-1 and 550b for a while now. Not full time but they are all open and I sit and stare when I have a little time to kill. They are all tricky little bastards indeed. The entire secret is in the switches for sure. One of these days I will figure it out but it will not be in the near future. I really need to more fully dissect one but I need time to make sure it can go back together properly. It cannot be sacrificial!  ;D  Custom Grayhills are probably the only real answer. They will be very steep $$ indeed.

I have heard of a guy out there who has a very good sounding, successful proto version of I think a 550a working. Don't know what his plans are or if he will ever let the world in on it.

For simplicity and since I am sorta of stupid  :D, I am gathering parts for a nice little inductor based, swinging input eq. I had originally thought of more true 553 but I am starting to lean more towards stepped cut/boost and 2x6 switches varying inductance/caps. An inductor on the high band as well for peak. High and low bands will be peak/shelf. Also with a discrete balanced receiver circuit. That will not be a copy of the input channel receiver but closely related. I will see as I have a lot of other things to get done as well.

Best, Jeff
Visit the CAPI store at http://www.capi-gear.com

CAPI is not affiliated with, endorsed by, or sponsored by API.

canidoit

I have been studying the 550, 550a, 550a-1 and 550b for a while now. Not full time but they are all open and I sit and stare when I have a little time to kill. They are all tricky little bastards indeed. The entire secret is in the switches for sure. One of these days I will figure it out but it will not be in the near future. I really need to more fully dissect one but I need time to make sure it can go back together properly. It cannot be sacrificial!  ;D  Custom Grayhills are probably the only real answer. They will be very steep $$ indeed.

I have heard of a guy out there who has a very good sounding, successful proto version of I think a 550a working. Don't know what his plans are or if he will ever let the world in on it.

For simplicity and since I am sorta of stupid  :D, I am gathering parts for a nice little inductor based, swinging input eq. I had originally thought of more true 553 but I am starting to lean more towards stepped cut/boost and 2x6 switches varying inductance/caps. An inductor on the high band as well for peak. High and low bands will be peak/shelf. Also with a discrete balanced receiver circuit. That will not be a copy of the input channel receiver but closely related. I will see as I have a lot of other things to get done as well.

Best, Jeff
Wow, I didn't realise how complex these switches were. Is it possible to individualize the switch they have. Like make the diy into a rack module and have the frequency, q and gain on individual separate switches?
iva dunit formerly known as canidoit

haima

Yes, this is totally possible. The main difficulty is squeezing things onto the 500 series panel space - hence the concentric switches. If you are going 19" rack you can split everything out to separate switches, should be a bit easier.

No "Q" on the original units BTW.

haima

Jeff - Your "swingin" input plan sounds pretty good. ;D


jsteiger

No "Q" on the original units BTW.
No separate control for it but proportional indeed. I believe one of the decks decreases the q as you boost/cut. This is one of the things they eliminated with the a-1 version. Still a damn fine eq though.  :)
Visit the CAPI store at http://www.capi-gear.com

CAPI is not affiliated with, endorsed by, or sponsored by API.

okgb

Ahhh , Jeff , your exposure of intent [  in group Law ]
consitutes a contract to which you are now bound

But it'll be a great thing , we wish you well
and now get to hound you every other day !
[ kidding , of course ]
« Last Edit: January 07, 2011, 09:19:34 PM by okgb »
GKB Audio / Greg Boboski


haima

No "Q" on the original units BTW.
No separate control for it but proportional indeed. I believe one of the decks decreases the q as you boost/cut. This is one of the things they eliminated with the a-1 version. Still a damn fine eq though.  :)

I have some vague recollections of reading somewhere that "proportional Q" was achieved with swinging input EQs by making the cut/boost pot values large enough that the series resistance of the pot effectively made the requisite Q change - I assume "wide" at large values of cut/boost and "narrow" for small boosts/cuts?

The 550s probably do it a different way though...?

Biasrocks

Speaking of switches...
http://SharktankPro.com

"I'd rather use an SPX90 than a UA plugin....." Joe Barresi

haima

NICE. i want one. :D

Does that breadboard come with the lunchbox?  ;D
« Last Edit: January 07, 2011, 10:38:47 PM by haima »

jsteiger

... - I assume "wide" at large values of cut/boost and "narrow" for small boosts/cuts?
Actually just the opposite. They narrow with more boost and cut. http://www.rane.com/note122.html

Quote
The 550s probably do it a different way though...?
It's a unique variation of a bridged-tee filter.
Visit the CAPI store at http://www.capi-gear.com

CAPI is not affiliated with, endorsed by, or sponsored by API.

jsteiger

...consitutes a contract to which you are now bound...
;D ;D ;D ;D OK! :)
Visit the CAPI store at http://www.capi-gear.com

CAPI is not affiliated with, endorsed by, or sponsored by API.

haima

... - I assume "wide" at large values of cut/boost and "narrow" for small boosts/cuts?
Actually just the opposite. They narrow with more boost and cut.

Ahh yes, that makes sense. At the far ends of the pot there is more series resistance, hence higher Q...

Therefore, aren't all "swinging input" EQs "proportional Q"? at least to some degree (depending on pot value)?

Can someone please explain (or at least summarize) "swinging inputs"??

Cheers!

okgb

Hey Jeff , how's the 550 work going ?
[ according to group Law ]
GKB Audio / Greg Boboski

QUEEF BAG

hmmm... there is one or two versions of  of the 550L that have a
spot on the pcb for a Q trim pot. (not fitted on ours)


Randyman...

Is the complexity of the switches partially due to their concentric nature?  I could care less if the knobs are concentric on a clone (separate Freq/Gain knobs) - but this would obviously increase the needed real estate on a front panel (I'm looking for rack-mount anyway - not 500 series).  It's the sound we're after - not the look - right?

Those switches do look very intimidating - but I could see them being a bit easier to tackle as individual switches instead of a single concentric 100-wafer switch (slight sarcasm :D ).

Preamps are done - I'm tackling compressors now - EQ is next  :)  This is on my radar...


8)
Randy V.
DIY just to get by


 

Related Topics

  Subject / Started by Replies Last post
3 Replies
1808 Views
Last post September 19, 2005, 10:37:48 PM
by Ethan
18 Replies
9790 Views
Last post May 10, 2011, 06:01:06 AM
by volker
91 Replies
6194 Views
Last post June 30, 2020, 01:05:09 AM
by boji
0 Replies
106 Views
Last post May 29, 2020, 02:32:26 AM
by gg85