REDD EQ, Helios 69 and Dick Swettenham

[Strawtles]

you are referring to the prototype PCBs or definitive?

 

[ruffrecords]

you are referring to the prototype PCBs or definitive?

Prototype.

Cheers

Ian

 

[ruffrecords]

The prototype REDD EQ PCBs arrived in the post this morning. I am trying a new PCB supplier Quick-Teck. They are a UK based Chinese family with a PCB factory back in China. An initial visual inspection of the PCBs indicates they are of good quality.

I will build and test one over the next couple of weeks.

Cheers

Ian

 

[Fablab]

Great!

 

[buildafriend]

YEEEHAWWW!!!

 

[ruffrecords]

I have got the prototype REDD EQ basically working. There are three errors on the PCB but the workarounds are easy. I had to rationalise some of the resistor values either to standard values or the nearest I had to hand but the errors should result only in small fractions of a dB change in response. At the moment bass boost works as advertised. Treble boost and cut max at 9dB rather than 10 as do the brilliance boosts and cuts. There's something wrong with the bast cut which seems to go in 1dB steps instead of 2dB steps.

The minor errors are the PAD 0V is not connected to 0V and one end of R11 is also not connected top 0V. A couple of links fix these. The other error is I used the wrong size footprint for the brilliance boost inductor (VTB9044). Fortunately I used one that was too big so as a workaround I have glued the inductor to the PCB up side down and wired it to the PCB pads. If you decide to use a Chrion inductor then this is not a problem.

The 1dB error on max boost/cut is probably due to resistor rationalisation so I need to revisit that. Bass cut problem I am not sure about.

Pic attached.

Cheers

Ian

 

[baadc0de]

Looking good Ian!

Will you be making another run with the errors fixed?

 

[Strawtles]

Ian said that this board is a prototype, so he can fix the problems before to realize the definitive PCBs

 

[ruffrecords]

Looking good Ian!

Will you be making another run with the errors fixed?

Yea, I will. I did get quite a few prototypes made because getting 10 made is as cheap as getting 3 made.

Cheers

Ian

 

[Fablab]

Hi Ian, have you made any sound test?

 

[ruffrecords]

Hi Ian, have you made any sound test?

Not yet. I will do that once I am confident it is working correctly.

Cheers

Ian

 

[Strawtles]

Hi Ian, it is possible to know when the definitive PCBs will be avaible?

 

[ruffrecords]

Hi Ian, it is possible to know when the definitive PCBs will be avaible?

I am retired now so I no longer work to schedules.!! However, I expect to have all the prototype board problems solved in the next couple of weeks. Allow another couple of weeks for the new version of PCB to be made so lets say about a month in total.

Cheers

Ian

 

[Strawtles]

Thank you. Keep us informed!

 

[ruffrecords]

Good news. The bass cut problem was a test kit set up problem that is now resolved, bass cut works as advertised. I have now measured every single setting of each of the three controls. All the boosts are close but a bit high at the last two settings. All the mid boosts are a little short on the max cut. If you are interested in the rew resuslts they are here:

http://www.ianbell.ukfsn.org/EzTubeMixer/docs/EzTubeMixer/REDDEQ/prototests/redd/

Click on any of the .htm files - each graph is labelled.

Cheers

Ian

 

[ruffrecords]

I have now tweaked a couple of resistor values in the brilliance cut and the cut now reaches 10dB (it is a little more at 10KHz because of the lower total series resistance due to the inductors). Also, the EQ was designed to be fed from a 10K fader in the EZTubeMixer and so was designed with a 2.5K source resistance. When this resistance is added in series with the input the boost hits 10dB on the nose too. So I am now happy with the response. If you omit this resistance the boosts are increased by a dB and are slightly sharper which is much the same as what is reported to happen in the real thing. Next step is to fix the PCB layout. In the meantime I might pass some music through it to see what it sounds like.

Cheers

Ian

 

[Strawtles]

Yes, let us know something about the sound!
Cheers

 

[ruffrecords]

Yes, let us know something about the sound!
Cheers

I am going to run a track through it and record the result, perhaps with a commentary about the EQ settings on another track. I'll try posting a wav of the result to dropbox.

Cheers

Ian

 

[ruffrecords]

Hopefully, here is a link to a wav file of a test of the REDD EQ. The left channel is the track via the REDD EQ and the right is me saying what the EQ setting is at each point. I have normalised the track to take out the EQ loss.

http://dl.dropboxusercontent.com/u/65071114/reddeqtestnormalised.wav

Cheers

Ian

 

[Fablab]

It is my impression ... or this equalizer sounds really cool?