Quad Eight CA-227 Project Feeler

I've been researching Quad Eight and trying to find some CA-127a cards to make some CA-227 preamps. They are getting scarce although I think that Orphan Audio may sell them as well as Kits to make CA-227 from them. I have to admit I've never heard one so I am going on what I've read on these and pure curiosity.

I'd like to make a few from scratch and was thinking of making some PCBs.
If there is enough interest I could make PCBs available (otherwise I would probably home etch them).

Does anyone have access to a good CA-227 schematic? I have the AM-10 but not a readable version of CA-227 (10 transistor version).

Thanks.

Jim

the transformer is a prime candidate for diy, just a quad filar, just like the api.

hey, i wonder if thats where they got the "quad" part of the name from?

I was in contact with David Geren at Cinemag a while ago. Cinemag has engineering drawings for the old QE transformers. He was going to build me some QEE-3442 outputs (with steel laminations like the original), but we lost contact. But he's the guy to ask.

http://www.cinemag.biz/

Knew he made the input but not the output. Thanks.

Still no schematic! Anyone?

Jim

i will be watching this thread.  a 500 series quad eight would be amazing (just throwing that idea out there)....

I really like Quad Eight stuff. it's my go-to pre at the studio.(well worth the time)
I hope someone chimes in here with at schematic i would be curious to see it as well.

Cheers
Robert

Robert, a 500 series is not out of the question but it would have to be the GroupDIY 51x rack to at least feed it 24v!

If you have a CA-227 would you mind taking a detailed photo of solder side as well as component side? I've already done the AM-10 layout and I just want to see what the original pre's other components were before I do a final layout.

Everyone who has used a Quad has good things to say about it.

Jim

it's those blue boards, i swear...

hi jim,
check out this website for a DIY version.  jesus (a member here - sverige_cruz) has already done a project with a PCB layout, though using non-original transformers.  http://www.geocities.com/more_quad_eight/

i really wanted to do one and jesus was very kind in sending me info for his build, but i've been waiting for a good output transformer candidate.  i get the feeling that the sound comes from the proper transformers, though i don't have any experience with them.  doug (EMRR) has made QE mic pres with QE PCBS and edcor 1:1 outputs and said it sounds fine and i think has even said that the QE mic pre circuit sounds fine unbalance out, which i've also read some prefer.

hi CJ,
do you have any info on this QEE-3442 output transformer?  i seem to remember reading something about the 3442 saturating differently than the 3041 (which is smaller and sounds cleaner and has a lower saturation level).
the QEE-3442 is what we really need info on.  CJ needs something to hack! ;D

Orphan audio / Ken H. (owns the rights to the QE and Electrodyne stuff) does sale a PCB with the QEE-3442 output at a reasonable price i suppose and Ken seems like a helpful person. 
though you guys are talking about a 500 series?

regards,
grant

dissonantstring said:

hi jim,
check out this website for a DIY version.  jesus (a member here - sverige_cruz) has already done a project with a PCB layout, though using non-original transformers.  http://www.geocities.com/more_quad_eight/
i really wanted to do one and jesus was very kind in sending me info for his build, but i've been waiting for a good output transformer candidate.  i get the feeling that the sound comes from the proper transformers, though i don't have any experience with them.  doug (EMRR) has made QE mic pres with QE PCBS and edcor 1:1 outputs and said it sounds fine and i think has even said that the QE mic pre circuit sounds fine unbalance out, which i've also read some prefer

Click to expand...

Yes, I am in touch with José and he will be sending me some info. His build is not based on the AM-10 though. But maybe I can use some of his info to put together a CA-227 like pre. Yes, you can run the pre unbalanced just fine.

Orphan audio / Ken H. (owns the rights to the QE and Electrodyne stuff) does sale a PCB with the QEE-3442 output at a reasonable price i suppose and Ken seems like a helpful person. 
though you guys are talking about a 500 series?

regards,
grant

Click to expand...

I got in touch with Ken and I am still waiting for a response about schematics. Not sure he owns the rights though. owning a name does not necessarily denote rights to designs. Ken if you are reading this please let us know about that and if we are overstepping our bounds here. My intention is to build a few for myself and make the project available to the group in the spirit of DIY not to make an exact replica of something that is currently in production. All that said the original design parts are not all available so I've had to find substitutes for them.

I've thought about buying the kit from Orphan Audio but I've yet to buy a KIT because I love the entire process of building from scratch. But if you are looking for a Quad pre and you don't want to wait or have to buy pcb, parts etc I would just get Orphan Audio's Quad kit. Also my project will not be exactly like that kit.

Jim

dissonantstring said:

doug (EMRR) has made QE mic pres with QE PCBS and edcor 1:1 outputs and said it sounds fine and i think has even said that the QE mic pre circuit sounds fine unbalance out, which i've also read some prefer.

Click to expand...

http://www.groupdiy.com/index.php?topic=5440.msg284394#msg284394

Ken's people were not at all happy with my use of the exact logo, even for a few builds.  This was interpreted initially as a counterfeit(!). 

I have never felt the need to put someone else's logo or name on my front panels. Thanks for the link.

Question: Why is it when I look at the schematic and look at the photos there are components missing?

Also the cards have 10 transistors and I presume that is an AM-10 in there but if I look at AM-10 its a slightly different schematic.

Jim

Bluzzi said:

I have never felt the need to put someone else's logo or name on my front panels. Thanks for the link.

Question: Why is it when I look at the schematic and look at the photos there are components missing?

Also the cards have 10 transistors and I presume that is an AM-10 in there but if I look at AM-10 its a slightly different schematic.

Jim

Click to expand...

Well, if it's a real Quad Eight, you put Quad Eight on it, right?  Which I did.  Quad Eight in a different font would not have riled them so.  Pretty different from a clone or repro with a name on it.

I'm not sure if this is really right, but off the top of my head:

5 transistor AM-3?
6 transistor AM-4?
(there are apparently both potted module and open circuit board variations)
9 and 10 transistor AM-10 and ?
Seen all with the same input and output transformers, I'm pretty sure.  

i have a 10 transistor quad eight board with the output all hacked up.

it is just an api on steroids.

I never knew i wanted one , but i'm in
for support at the least , thanks Jim

emrr said:

Well, if it's a real Quad Eight, you put Quad Eight on it, right?  Which I did.  Quad Eight in a different font would not have riled them so.  Pretty different from a clone or repro with a name on it.

Click to expand...

Yeah, I can see that. That's why I don't encourage putting logos etc. Building a circuit for ourselves only and for our own pleasure is cool. When you start to put an active brand name on it I can see where some would see that is stepping over the line.

I'm not sure if this is really right, but off the top of my head:

5 transistor AM-3?
6 transistor AM-4?
(there are apparently both potted module and open circuit board variations)
9 and 10 transistor AM-10 and ?
Seen all with the same input and output transformers, I'm pretty sure.  

Click to expand...

I only have a 10 transistor schematic of the AM-10. When you look at the 990 and the AM-10 you start to see many similarities. Did Deane Jensen work on the AM-10 or was he gone from Quad by then? I wonder.

Jim

Don't mean to push too far off topic, but here's an article that ran in Tapeop a few years back that covers some of the history of quad eight, with mention of Deane Jensen's role as well as the namesake optical process:

http://www.cinemag.biz/electrodyne/electrodyne_part_1.html

ok, so that is a Richenbach output, that means that cinemag has the prints.


i think John Hall did some Langevin stuff,

similar names, AM4, AM16, all those guys back then knew each other because they switched companies so often, and everybody originally came from the womb of W.E.

there was some transistor matching going on, the original boards have colored tops on some of the small transistors, aka DBX early VCA's.

but todays transistors are more evenly matched, so screw the sorting.

Yes, Q2 and Q4 are matched.

Jim

I found this schemo on some japanese site..  it looks similar to an aM10 schemo I found recently too. Maybe it will shed some light, although I don't see an input trafo.. could that have been left off the schemo or could this be a line amp?

As an aside... an AM10 may be useful as a 2520 footprint DOA...

mitsos said:

I found this schemo on some japanese site..  it looks similar to an aM10 schemo I found recently too. Maybe it will shed some light, although I don't see an input trafo.. could that have been left off the schemo or could this be a line amp?

As an aside... an AM10 may be useful as a 2520 footprint DOA...

Click to expand...

Thanks Mitsos. Yeah, this is the same schematic that I have. I also have a schematic for the AM-10. What I am trying to determine is why the AM-10 part in the CA-227 is slightly modified?

It would be nice if someone could send me some close up photos of a full working CA-227 (component side as well as solder side). It might reveal some things that are not on schematics.

If I don't get one soon I'll go ahead and begin gathering components to start prototyping.

I'm not trying to duplicate a CA-227 exactly (which is impossible with new components) but to come up with a newer design with currently available components.

Jim