Reddish 500 EQ

[JMan]

I had a fascinating conversation with @nielsk this evening in which he regaled me with some history of the 500 format and API consoles. I learned quite a few things I didn't know!

I wanted to share a practical takeaway from the conversation with builders of the Reddish EQ. If you find that the unit produces lots of unwanted distortion (which is not what it should do), you may find that running a wire between the Audio GND and Power GND pins on the edge connector solves this issue. The short version is that this relates to how those ground connections are handled internally within your specific lunchbox/rack, and they are not all the same. There should be no negative effects of making this connection.

@creature.of.habit I am almost certain that this is what we were dealing with when you first plugged in your unit, and why swapping out the rack for a different model cured the issue.

 

[creature.of.habit]

@creature.of.habit I am almost certain that this is what we were dealing with when you first plugged in your unit, and why swapping out the rack for a different model cured the issue.

Very likely indeed. There were all sorts of problems with that rack, though, not just with the Redd. I was very glad to see it go.

 

[dmp]

The faceplates are a little wide (+0.02") for a 500 rack. When I have these in 11 modules will not fit. The spec is 1.5" but once painted they are more, so if you do another run, reduce the width.

 

[MidnightArrakis]

The faceplates are a little wide (+0.02") for a 500 rack. When I have these in 11 modules will not fit. The spec is 1.5" but once painted they are more, so if you do another run, reduce the width.

[The faceplates are a little wide (+0.02") for a 500 rack] -- >> ALL << of the "500-Series" panel-width dimensions that I see mentioned or shown here on this forum are basically incorrect!!! And, I keep on making mention within the various threads on this forum that using the stated -- 1.50" (38.10mm) -- panel-width is the wrong width dimension to use, but.....nobody on this forum ever listens to me!!!

With following the nominal and typical tolerance dimensions as used by your average run-of-the-mill "rack-equipment" standards, a "500-Series" panel-width dimension would be -- 1.47" (37.34mm) -- and your panels will work out to be just fine. This works out to be 0.030" less (actually, 0.015" X2) than the stated nominal panel-width (1.50" minus 0.015" X2 = 1.47").

And, once again, putting this tolerance into the EIA-310D "rack-standards" usage.....a 1U rack-panel height is stated to be 1.75" high. But, of course, if you actually made your rack-panel 1.75" high, it's -- NOT -- gonna fit!!! So, you reduce the panel-height by 0.030", so you end up with an -- ACTUAL PHYSICAL DIMENSION -- of 1.72" high (1.75" minus 0.015" X2) and ALL IS WELL!!! And, this same tolerance application applies to -- ALL -- rack-panels, no matter how many U's they may be.

And.....let me go ahead and mention this aspect of the "500-Series" panel-height one more time.....it should also follow the same tolerancing as the rack-panels do!!! Meaning, their stated height is of their being -- 5.25" (133.35mm) -- high. So.....you make your "500-Series" panel that high and it ain't gonna fit!!! However, by following the standard EIA-310D rack-panel standards, you would have your panel fabricated to be -- 5.22" (132.59mm) -- high (5.25" minus 0.015" X2 = 5.22") and then your panel will end-up fitting HUNKY-DORY!!!

Bottomline.....I have only been designing professional "rack-mount" equipment since 1975, so "WHAT THE F**K DO I KNOW" about panel designs and their tolerances??? Certainly nowhere nearly as much as the members on this GroupDIY forum apparently do!!!

https://groupdiy.com/threads/diy-rack-enclosure-extrusion.88722/post-1173708

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[ruffrecords]

@MidnightArrakis is right. 1.5 inches is the module pitch not the panel width which needs to be a little less to avoid fitting problems. In the same way, in Eurorack synth modules, 8HP equates to a modules pitch of 1.6 inches but the panel width needs to be slightly less than this and the preferred values are all called up in the DIN spec.

I don't know if there is an equivalent spec for 500 series modules.

Cheers

Ian

 

[nielsk]

API spec IS 1.5" wide, and the hole spacing in an actual API rack allows for this.
Like so many of the plethora of "500 series compatible" products that abound many racks do not have the correct hole spacing (among many other problems), so under-sizing the F/P width is not a bad idea.
Even the API 11 space rack filled with API modules is a tight fit at best, it was a flawed concept IMHO.
A careful file on the sides to remove the powder coat may be the simple answer...

 

[ruffrecords]

So basically the 500 series module mechanics are poorly specified.

Cheers

Ian

 

[JMan]

Anyone who will order a custom panel from Frank, you could ask him to reduce the width accordingly. FWIW my prototype lives comfortably in a full 11-space CAPI rack without modification...

 

[dmp]

Yes, just reduce the width a bit with a file or sandpaper - should be good. I was fitting these in a 11 space 51X rack from CAPI as well, but it is a very old one. I didn't mean to sound critical - this is an amazing project. Actually doing DIY is a journey filled with small mistakes to overcome.

 

[MidnightArrakis]

So basically the 500 series module mechanics are poorly specified.

Cheers

Ian

[So basically the 500 series module mechanics are poorly specified] -- I am personally very seriously rather hesitant to make this statement, but.....way back in 1986, I was working as a "Contract Senior Mechanical Designer" at a telecommunications company that was located in Springfield, VA. One day while I was driving around looking for a place to go to for my lunch, I ended up behind the wing of a small strip-mall, thinking that the route I was taking would take me to a WENDY's (hamburger place). The road didn't go through to the WENDY's, as there was a steep hill that created a wall back there. However, there was a concrete staircase built into the hill that would take you up to and into the WENDY's parking lot.

As I got out of my car and because I had never been at this location before, basically stuck behind a strip-mall in a kind of cul-de-sac, I looked around at the store windows behind me. As I was scanning the various doors and windows of the businesses that were tucked-in behind this strip-mall, my eyes caught what appeared to be the schematic symbols of op-amps on one of the doors. And, because of "how" the schematic symbols were shown on the door, I then thought, "C'MON!!! Is -- THAT -- the API logo"???.....

Now being curious, I walked over to the door and went in. -- NOBODY THERE!!! -- ..... I walked in a little further and said, "Hello"??? Eventually, Paul Wolff himself came out and said to me, "May I help you"? I replied, "Is this API, the audio company"? Paul said, "Yes, it is". Long story short, Paul Wolff takes me back into their lab area and gives me "the nickel tour" of the facility and we start talking about audio equipment designs. Eventually, I had to leave in order to get something to eat, but that accidental venture and discovering that API, Inc. was located not far from the telecommunications company I was working at, began a loose relationship where I would stop by the API office rather frequently so Paul and I could chat about equipment designs and ideas.

During a few of my visits, I would share with Paul some of my mechanical designs of the rack-mounted telecommunications gear that I was designing for the company. Then, on one day, Paul mentioned to me that he was working on this new concept of small audio modules that would be placed into a portable case called a "Lunchbox". Since all of these ideas of his were simply "ideas" and they hadn't gotten to the point yet of actually becoming a reality -- AND -- because Paul was somewhat impressed by the type of "rack-mount" chassis designs that I was doing for the telecommunications company, Paul had said to me, "It seems as though you would be a good candidate to assist me with the mechanical designs of these modules and the "Lunchbox"!!!

However and unfortunately, there was a huge personnel shakeup within the telecommunications company and they ended-up terminating a bunch of us "Contractors". So, because the drive between where I lived in Maryland and where API was located in Springfield, Virginia was over an hour long and around the horrendous Washington, DC beltway, I never made it back there.

Meaning.....if I had actually been the person to create the mechanical design and dimensions of the "500-Series" modules and its associated "Lunchbox", more than likely none of these current-day mechanical-fit issues would even exist!!! YEAH!!!.....I know.....a rather bold statement for me to make, right? Well.....if you have happened to see some of my other responses within other threads on this forum where I have pasted either images or links to some of my other "rack-mount" equipment designs I have created for other various companies, R&D laboratories and defense contractors, then you would understand my confidence.

In any case.....with all of the -- brew-ha-ha -- messed-up mechanical designs and documentation files I have seen from API itself, RADIAL Engineering and others concerning their "500-Series" modules and "Lunchbox" designs, I really do wish that I had been involved with the creation of this series of audio equipment. At least there would have been something that "made sense" and was properly documented. >> ALL << of what I have seen online concerning the mechanical details of the "500-Series" line of equipment is either GARBAGE OR TRASH AND AT THE MINIMUM.....INCORRECT!!!

Just my inflationary devalued 2-cents worth!!!

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