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General Discussions => The Lab => Topic started by: canidoit on January 07, 2011, 07:27:27 AM

Title: Will an API 5500, 550a or 550b inspired or clone ever come to the DIY world?
Post by: canidoit on January 07, 2011, 07:27:27 AM
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.
Title: Re: Will an API 5500, 550a or 550b inspired or clone ever come to the DIY world?
Post by: bruno2000 on January 07, 2011, 07:56:26 AM
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
Title: Re: Will an API 5500, 550a or 550b inspired or clone ever come to the DIY world?
Post by: okgb on January 07, 2011, 08:36:42 AM
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 ?
Title: Re: Will an API 5500, 550a or 550b inspired or clone ever come to the DIY world?
Post by: QUEEF BAG on January 07, 2011, 04:46:21 PM
now they use grayhills that solder right to the circuit board

no dickin' around with wires.

i wouldn't wanna take it on though...
Title: Re: Will an API 5500, 550a or 550b inspired or clone ever come to the DIY world?
Post by: jsteiger on January 07, 2011, 05:28:59 PM
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
Title: Re: Will an API 5500, 550a or 550b inspired or clone ever come to the DIY world?
Post by: canidoit on January 07, 2011, 06:39:40 PM
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?
Title: Re: Will an API 5500, 550a or 550b inspired or clone ever come to the DIY world?
Post by: haima on January 07, 2011, 07:20:02 PM
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.
Title: Re: Will an API 5500, 550a or 550b inspired or clone ever come to the DIY world?
Post by: haima on January 07, 2011, 07:28:33 PM
Jeff - Your "swingin" input plan sounds pretty good. ;D

(http://ia.media-imdb.com/images/M/MV5BNDYxNTYzOTY3OF5BMl5BanBnXkFtZTYwOTk4NTE3._V1._SX475_SY332_.jpg)
Title: Re: Will an API 5500, 550a or 550b inspired or clone ever come to the DIY world?
Post by: jsteiger on January 07, 2011, 07:58:15 PM
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.  :)
Title: Re: Will an API 5500, 550a or 550b inspired or clone ever come to the DIY world?
Post by: okgb on January 07, 2011, 09:07:01 PM
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 ]
Title: Re: Will an API 5500, 550a or 550b inspired or clone ever come to the DIY world?
Post by: haima on January 07, 2011, 09:50:17 PM
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...?
Title: Re: Will an API 5500, 550a or 550b inspired or clone ever come to the DIY world?
Post by: Biasrocks on January 07, 2011, 09:57:05 PM
Speaking of switches...
Title: Re: Will an API 5500, 550a or 550b inspired or clone ever come to the DIY world?
Post by: haima on January 07, 2011, 10:04:55 PM
NICE. i want one. :D

Does that breadboard come with the lunchbox?  ;D
Title: Re: Will an API 5500, 550a or 550b inspired or clone ever come to the DIY world?
Post by: jsteiger on January 07, 2011, 10:21:20 PM
... - 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 (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.
Title: Re: Will an API 5500, 550a or 550b inspired or clone ever come to the DIY world?
Post by: jsteiger on January 07, 2011, 10:31:37 PM
...consitutes a contract to which you are now bound...
;D ;D ;D ;D OK! :)
Title: Re: Will an API 5500, 550a or 550b inspired or clone ever come to the DIY world?
Post by: haima on January 07, 2011, 10:37:39 PM
... - 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)?
Title: Re: Will an API 5500, 550a or 550b inspired or clone ever come to the DIY world?
Post by: johnnyscotch on January 08, 2011, 02:21:40 AM
Can someone please explain (or at least summarize) "swinging inputs"??

Cheers!
Title: Re: Will an API 5500, 550a or 550b inspired or clone ever come to the DIY world?
Post by: okgb on January 08, 2011, 07:37:19 AM
Hey Jeff , how's the 550 work going ?
[ according to group Law ]
Title: Re: Will an API 5500, 550a or 550b inspired or clone ever come to the DIY world?
Post by: QUEEF BAG on January 08, 2011, 05:01:29 PM
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)

Title: Re: Will an API 5500, 550a or 550b inspired or clone ever come to the DIY world?
Post by: Randyman... on January 08, 2011, 07:31:33 PM
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)
Title: Re: Will an API 5500, 550a or 550b inspired or clone ever come to the DIY world?
Post by: jsteiger on January 08, 2011, 08:58:18 PM
It could be done as separate controls instead of concentric but they would probably still be customs. On a 550b, the frequency select is a 3 deck switch and the cut/boost is a 4 deck switch.

Here are a few pics of a 550a-1 just for the heck of it. Remember, this one is different as the Q is constant not proportional. And of course the presence of IC's and only one 2520. The switches are not as complicated but still not exactly a stroll thru the park.  :D  Even with all the negative talk over the years, this is still a damn, fine sounding equalizer.

A lonely 2520...
(http://i276.photobucket.com/albums/kk12/jsteiger1965/550a-1/1_550a-1.gif) (http://i276.photobucket.com/albums/kk12/jsteiger1965/550a-1/1_550a-1-1.jpg)

And those slightly less but still bastard rotary switches...
(http://i276.photobucket.com/albums/kk12/jsteiger1965/550a-1/2_550a-1.gif) (http://i276.photobucket.com/albums/kk12/jsteiger1965/550a-1/2_550a-1-1.jpg)

Best, Jeff
Title: Re: Will an API 5500, 550a or 550b inspired or clone ever come to the DIY world?
Post by: kazper on January 08, 2011, 09:19:45 PM
http://www.hyperspasm.com/hyperblog/wp-content/uploads/2009/03/550a.pdf

Thats the cleanest copy of the 550A schematic I've seen!

Funny thing is looking at the schematic and then the pictures it's like where is the missing stuff at...

must be dual sided switches...
Title: Re: Will an API 5500, 550a or 550b inspired or clone ever come to the DIY world?
Post by: mulletchuck on May 15, 2011, 02:09:08 AM
I have a question on the 550b.   some of the capacitor networks are duplicates in value:

(see attached pic)

Does this mean that these can be consolidated into a single signal path?   in my noobness, it seems redundant.    I used the schematic from the GroupDIY account, in case anyone is curious where I got this pic from.