Barry Porter "Net EQ"

[druu]

Ok I stand corrected. I must have had a brain fart during that stage and switched my wire colours for some reason.

 

[frazzman]

Ahh thanks dudes! You were right about the the neg and pos wires being reversed.

Druu: I remember you telling me about your problem now...

I wrongly made the assumption that the pin out was the same on both connectors. I wish I'd noticed the square pad earlier ...

I can hear relays kicking in and LEDs lighting up... Hopefully some audio to follow! Thanks again

 

[petermontg]

whats the current I need. Am still dropping voltage and drawing 1.5A

 

[frazzman]

Looking good here so far... Wired up one band and boost/cut is working.

A few observations when analysing using RMAA:
- max boost seemed to be a bit under 4db at max position - using 21 step rotary, I was expecting 5db?
- on the freq plot the Q control looks pretty much the same at q=1 and q=3. Is there supposed to much difference here? They are both broad Q's I guess but I can't hear/see the difference. - I'm using 12 pos alpha rotaries for Q control 

I'll wire up the rest and report back...  I'm just interested on other peoples findings. Once these boards are wired up I really don't wanna have to pull them out to tweak something

 

[Gustav]

Looking good here so far... Wired up one band and boost/cut is working.

A few observations when analysing using RMAA:
- max boost seemed to be a bit under 4db at max position - using 21 step rotary, I was expecting 5db?
- on the freq plot the Q control looks pretty much the same at q=1 and q=3. Is there supposed to much difference here? They are both broad Q's I guess but I can't hear/see the difference. - I'm using 12 pos alpha rotaries for Q control 

21 steps doing what? Have you measured resistance over the switches to confirm you did them correctly?

I went to Jakob to bring this to life the first time, and he made a few plots at random settings for me (attached). You can see one of them has a pretty sharp Q.  My Q ranges from 1 to 3.

Again, just to get the trivial sources for error out of the way. Did you measure the Q switch to confirm it adds up the values as expected?

Also -  Did you change/omit the resistors on the PCB mentioned in Harpo's sheet?

Gustav

 

[frazzman]

Hi Gustav,
Thanks for the reply.

For the gain switches I went with 21 steps: -/+ 5dB with step 11 as 0db (centre tap)

I checked the sum of the resistors on each gang for every switch to make sure that it matched up with Harpo's values (and the other gang(s) on the switch).  All Freq's, gain switches and Q switches

Everything was pretty dead on. As far as the gain switches go, not too much room for error since its just a continous ring of the same value resistor anyway...

I wired up a few other Q switches tonight to see if the problem still persists (they're on molex headers so easy to swap in and out). Same issue... with tests just limited to MF1 band - the plots are identical with both Q=1 and Q=3, changing the Q position has no affect. I can hear clicks in the audio as I toggle through the switch positions, FWIW.

I followed all the resistor shorts positions and omissions as per Harpo's spreadsheet(s) - (at least I think I did...)

The only thing I can think that may have caused a problem is that for the Q Switches - I used the Q calculations from one of Harpo's earlier spreadsheets. This contained calcs for a 12x1 rotary switch... (see attached)
I then used one of the the later revision spreadsheets and followed the calcs specified for 24pos freqs and 21pos gain switches.

Perhaps the 'merging' of these two different sources has caused an issue - i.e. maybe wrong shorts/ommisions of certain resistors?

The only other loose end I have is that I have only wired up 1 band at the moment, but I don't think that will be causing any issue.

Man, I wish I had have wired up the leads to switch lugs prior to populating all the switches. Trying to solder leads to the middle pole of the LF and HF switches is a total pain...

I also need to work out why I seem to be 1db short as well for both boost and cut...

This is a full on project...

Thanks for your help

 

[Gustav]

The only thing I can think that may have caused a problem is that for the Q Switches - I used the Q calculations from one of Harpo's earlier spreadsheets. This contained calcs for a 12x1 rotary switch... (see attached)
I then used one of the the later revision spreadsheets and followed the calcs specified for 24pos freqs and 21pos gain switches.

Whats the R sum on your Q switch?

Cant figure out the mystery on the missing 1dB on the gain switches, other than resistor-fairies. Only reasons I am sharp enough to propose is, its either  because you're tapping them the wrong place, or have a wrong value somewhere left on the board.

 

[Harpo]

... with tests just limited to MF1 band - the plots are identical with both Q=1 and Q=3, changing the Q position has no affect. I can hear clicks in the audio as I toggle through the switch positions, FWIW.

I followed all the resistor shorts positions and omissions as per Harpo's spreadsheet(s) - (at least I think I did...)

you probably only missed to jumper two circuit nodes, as the quoted headline of the calcsheet snipplet already says '...and shorting out opamps non-inverting input with pin1 of the 'Q'-pot from Barrys schematic...'.

 

[frazzman]

... with tests just limited to MF1 band - the plots are identical with both Q=1 and Q=3, changing the Q position has no affect. I can hear clicks in the audio as I toggle through the switch positions, FWIW.

I followed all the resistor shorts positions and omissions as per Harpo's spreadsheet(s) - (at least I think I did...)

you probably only missed to jumper two circuit nodes, as the quoted headline of the calcsheet snipplet already says '...and shorting out opamps non-inverting input with pin1 of the 'Q'-pot from Barrys schematic...'.

Hi Harpo,
Yes - looks like I missed that instruction. I (wrongly) assumed that all the shorts and omissions listed would cover everything.

So pin  3 of opamp is non inverting input? So link pin 3 of opamp to pin 1 of Q switch? Is that correct ?

 

[petermontg]

Okay so going back over my relay selection there is Omron G6H-2-100 in there which is non-latching. Maybe I forgot it was the other part number I wanted....... The TQ2 is latching from the data sheet I could find. The TQ2 that matches 12VDC, 1,028K is single sided stable on the data sheet. I am correct in thinking the single side stable TQ2 is the correct one.

Best
Peter

 

[frazzman]

FI Q setting mono pot P10. Jumper the right and center hole on pcb and connect switch pole and switch position 1 to this jumper. Last switch position resistor goes to the left side hole. Jumper R110 or fit this last switch position resistor here instead so it doesn't hang lose on your Q switch.
Same procedure for the other Q setting switch asemblies.

I think I answered my own question, I think this is what you meant Harpo?

 

[kml23956]

Who can explain this in simple terms? I need to know what they are and how they are wired? Are they 2 pole 24 , 4 pole 24, 2 pole 23...etc.

 

[Gustav]

Who can explain this in simple terms? I need to know what they are and how they are wired? Are they 2 pole 24 , 4 pole 24, 2 pole 23...etc.

These are two 2 x 23 switches for the mid bands, and two 4 (only using 3) x 23 for the high and low bands. The third gang are the values for the shelving filters.

You can use any number of steps you like. Harpo has made some great excel sheets where you just plug in your data.

Gustav

 

[kml23956]

Thank you Gustav.

 

[frazzman]

Any ideas what could cause excessive boost on HF band? I fixed all other switch related issues and wired and tested each band as I go - only to find a a weird problem on my HF band.

To set the scene - I'm running off Harpos values - stepped switches set for 24 pos freq's, 21 step gain -/+ 5db with 0db at step 11. 12 step Q's.

Anyway I'm getting about +14db boost (at max) on my HF band and max +4dB on all others. No doubt there is something wrong on my HF band. There's no boost when shelving is engaged either. Tried swapping gain and Q switches with "known working" switches from other band but no go.

As per Harpos calcs - Boost and cut resistors (r13 and r14 are correct at 5k1 and r77,82,86,90 are correct at 6k49)

I'm thinking I forgot to change a resistor value or forgot to omit or short a resistor position, but nothing is staring back at me... Any ideas?

 

[petermontg]

Whats in R62?

 

[frazzman]

Whats in R62?

Peter, you're the man... I had 100k in R62 as per the JLM component overlay pdf, where as the schematic value is 10k. HF band now works.

Looks like this channel is all good for now. Still can't get quite to +5db on any bands but maybe RMAA is off as all resistors for cut and boost are correct. Q switches are working too as I can see on the frequency plot.

Now to wire the second channel.... Arghhhh.

Did you fix your power issue? Wrong relays ?

 

[petermontg]

I am waiting on a fluke meter to arrive to measure all these caps again.
AFAIK the relays are good. They have the same details etc as the other and test good.

It's something pretty small. I still have have a feeling it's in the summing section. There is a something out there somewhere. As when I had power before, this section worked. Bad BP/Ceramic in there not showing on the cheap meter I have now. Opamps and resistors test good. I will find it with the fluke better than the meter I have now.

Going to have a break from it and start the D-AOC soon. I tend to find problems when I step back a small bit from it.

Glad yours is working.

 

[e.oelberg]

I have this... cheap and precise and fast shipment
http://www.seeedstudio.com/depot/Capacitance-Meter-Kit-p-268.html

 

[petermontg]

Thanks e.oelberg