Hardware designing guide

[Sweetalk]

Hi!, I'm designing a new project with the FV, I've done a lot of pedals with it and always trying to lower the noise. Had some troubles with ground loops, and planes. The best results I got it using THT components, with the FV1 in the bottom of the board and the ground plane on the top, any thoughs about that?.

Also Frank suggested to add some decoupling caps in every power pin (Avdd, etc), is that really something that improves performance, noise or just some "good practice just in case" scenario?.

In some designs around the net I founded that the MID (pin 3)decoupling cap as 10uF instead of 1uF, better?, worse? (obviously, really easy to try but still on the design board so I'm asking too) and the one on REFP (pin 26) unpolarized instead of a polarized one.

[ice-nine]

Hi Sweettalk, I too am trying to lower the noise floor which is mainly too much hiss in my case which I have also noticed on many commercial pedals that I have tested as well, is this the same as yourself ?

I use the 10uf pin 3 and pin 26, The main Spin FV-1 datasheet shows the use of 1uf but the datasheet/schematic for the SpinDev board uses 10uf so I imagine not much difference here.

I tend to use mainly SMD parts with the ground plane on the bottom of the PCB, today I have just submitted two new PCB's for a project so I hope these will have a noise improvement, I will be interested in your results.

[Sweetalk]

Hi Sweettalk, I too am trying to lower the noise floor which is mainly too much hiss in my case which I have also noticed on many commercial pedals that I have tested as well, is this the same as yourself ?

I use the 10uf pin 3 and pin 26, The main Spin FV-1 datasheet shows the use of 1uf but the datasheet/schematic for the SpinDev board uses 10uf so I imagine not much difference here.

I tend to use mainly SMD parts with the ground plane on the bottom of the PCB, today I have just submitted two new PCB's for a project so I hope these will have a noise improvement, I will be interested in your results.

Yes, the floor noise is mainly hiss, also depending on the coding. I changed from inverting to non-inverting opamps buffers with great results, but there's still plenty hiss around

[ice-nine]

Yes, the floor noise is mainly hiss, also depending on the coding. I changed from inverting to non-inverting opamps buffers with great results, but there's still plenty hiss around

Yes using non-inverting op amp sections does lower the noise in the analogue audio path over inverting op amps, I use non-inverting in these designs. I also have the ability to use a jumper on the PCB which bypasses any digital side (for testing the analogue only) which can help pinpoint where any background noise is coming from.

I agree, depending on the code used the hiss can change level, I have used a simple read ADC write DAC code for testing as well and that should pass what you put in to the output without the hiss but it is still there.

It would be nice to get some other comments from others to see how this might be eradicated without destroying the frequency response .

[nacho_conso]

Hi, I don't know if this is related to what happened to me, but I was getting horrible hiss from the first PCB I soldered. In my design FV-1 is on top, and THT components on bottom. GND planes of both sides are connected through as many vias i could insert there.

The fact is that the main issue was Opamps quality. And I am talking about simple Tl072's. They had this serial number printed on package, above the TL072 inscription: "18MDSHY". In my design i had 2 of them. The first TL with both opamps in non-inverting and the last TL with 2 opamps in an inverting config. Changed both TL's with seemingly original TI TL072, and bye bye hiss. But of course, if you have tested your dry signal path and it doesn't have any hiss, opamps quality wouldn't be the problem so.

[Sweetalk]

Hi, I don't know if this is related to what happened to me, but I was getting horrible hiss from the first PCB I soldered. In my design FV-1 is on top, and THT components on bottom. GND planes of both sides are connected through as many vias i could insert there.

The fact is that the main issue was Opamps quality. And I am talking about simple Tl072's. They had this serial number printed on package, above the TL072 inscription: "18MDSHY". In my design i had 2 of them. The first TL with both opamps in non-inverting and the last TL with 2 opamps in an inverting config. Changed both TL's with seemingly original TI TL072, and bye bye hiss. But of course, if you have tested your dry signal path and it doesn't have any hiss, opamps quality wouldn't be the problem so.

Mine was not a quality issue, I use TLC2272 por buffers.

(Suerte Nacho! )