Accurate Inverse RIAA

[Max Headroom]

Thanks, yeah, should be interesting.
What I am getting at is to diffrentiate the nature of the underlying noise between different phono stages, might be illuminating.

Dan.

 

[scott wurcer]

Of course, the reverse also works, but on average, paralleling (or placing in series) tightens the tolerance of the network.

With FET's I've been serializing them in large batches and saving a best fit to Idss and Vp. Then even in Excel your can match up groups according to exactly how you are going to use them. I figure it would be trivial to loop through a simple list of 1% resistors and set up quads at .1% or even better.

BTW with a CD it's also trivial to inverse RIAA digitally a whole cut and play it through a phono beware though of staying minimum phase that goes for the Laplace function too (some folks have had issues).

 

[rayfutrell]

The old Apt Holman Preamp service manual has an inverse RIAA network schematic on page 52.

 

[stocktrader200]

Calvin, I did that test years ago to test my turntable and Cartridge. The difference being I adjusted the RIAA curve on the preamp so that the timbre difference between turntable and cd was perfect. the test album was Brothers in arms Dire Straights on LP and CD.
the MM cart easily sounds as good as MC with a 25 Db improvement in s/n.
net result is gentle boost below 50hz and above 6khz

 

[StevenCrook]

Gerbers are available at the link above as well.

I downloaded the Gerber zip file but when I upload to JLCPCB and PCBWAY both complain that the board has zero size.

Is this expected?

I'm still sorta new at this game...

 

[Bonsai]

Steven,

I'll take a look at it tomorrow. I have the original PCB file somewhere, so I can easily regenerate the board if needs be.

🙂

 

[Bonsai]

Hello Steven,

here are the Gerbers for the IRN. Some other folks also complained that the original zip file was corrupted.

I've updated the webpage as well with the new zip file

An Accurate Inverse RIAA Network

 

[StevenCrook]

Mmmm. I've just tried the updated zip file with jlcpcb, oshpark and I'm still getting a zero size board. jlcpcb say width and height are null and that it cannot determine the board outline. Oshpark also gripes about size/drill file.

I'll have a prod around, like I said I'm really not familiar enough with this sort of thing to be sure I fully understand what I'm being told by the fabricators...

JLCPCB Analysis Results #1
layers : 2
minimum trace width : >=10 mil
minimum trace spacing : >=10 mil
minimum drill size : 0.05 mm
width : null
height : null

JLCPCB Analysis Results #2
Can not identify the board outline
Inverse RIAA.DRL(null): Non-gerber274X/excellon formats
Inverse RIAA.GDD(null): Non-critical Gerber file
Inverse RIAA.GDG(null): Non-critical Gerber file
Inverse RIAA.GPM(null): Non-critical Gerber file
Inverse RIAA.MAT(null): Non-gerber274X/excellon formats
Inverse RIAA.TOL(null): Non-gerber274X/excellon formats

OSH Park Analysis results
Warning: File is not valid drill file: Inverse RIAA.DRL
Failure: Removed drill file, did not contain tool size information: Inverse RIAA.TXT See help page.
We couldn't find the board outline. See help page.

 

[rayma]

Looks like a Gerber file name problem.
Compare the name requirements for jlcpcb with the existing file names,
and change the suffixes to match jlcpcb if they differ.

 

[Bonsai]

Let me try to upload this to my PCB vendor because they have a Gerber reader - we can check if its a file problem or not

 

[Bonsai]

I've just checked - its also coming back with a size of zero. Let me investigate.

 

[rayma]

typical Gerber file names:

filename--------------corresponding layer
boardname.GKO------Board Outline
boardname.XLN-------Drills
boardname.GTO------Top Silkscreen
boardname.GTS------Top Soldermask
boardname.GTL------Top Copper Layer
boardname.GBL------Bottom Copper Layer
boardname.GBS------Bottom Soldermask
boardname.GBO------Bottom Silkscreen
boardname.G2L-------Internal layer 1 (next to Top)
boardname.G3L-------Internal layer 2 (next to Bottom)

 

[Bonsai]

Seems the problem is because I put two identical boards in next to each other (for stereo) and this is confusing the Gerber readers. I've made it a single board by deleting one of the boards from the file and its now uploading correctly into my board supplier's reader and they've accepted it for manufacture. (I must have only had 1 board in the Gerber file when I made my original unit 5 yrs ago)

I've ordered 10 so if you wait you can get one board for $7.50 or two boards for $11 plus postage of $2.50. They will be here in 7-10 days.

If you can't wait, the file that works with me is below.

Hopefully the issue is solved now 🙂

 

[StevenCrook]

Yup, that works on jlcpcb. I was going to order some of the inverse boards along with a some others I'm working on and want to make the best use of delivery charges.

 

[Bonsai]

No problem- glad it works now!

 

[Bonsai]

I've updated the first post on this thread - boards are now avaiablle if you want to buy them instead of etching them (just follow the link).

I've still left the Gerbers up on hifisonix as a service to the community if you still want to etch your own.

Happy RIAA'ing

🙂