REDD EQ, Helios 69 and Dick Swettenham

[ruffrecords]

Hi Ian, any news about this fantastic project?

Squeezing it in between the EZTube MIxer, the universal EQ and switch PCBs for the same!!

Cheers

Ian

 

[leadbreath]

hey ian i love u man.... :-*

 

[ruffrecords]

Following the information provided by Dylan concerning the actual shape of the Brilliance boost and cut curves, I have redesigned the circuit to use separate inductors for the brilliance boost and cut so as to keep the Q the same for both. This unfortuantely means another 2 pole 11 way switch is needed but I cannot see a way to avoid it. I have yet to work out all the component values but hereis the MKII circuit:

http://www.ianbell.ukfsn.org/EzTubeMixer/docs/EzTubeMixer/REDDEQ/MKIIcircuit.jpg

Cheers

Ian

 

[dissonantstring]

hi ian,
liking this project's progression.  thank you very much kind sir for all your time and energies.  i also like the way you arc the switch position connections in your schem.   
best,
grant

 

[ruffrecords]

I have done some simulations of the new design which confirms the brilliance boost and cut Q can be made the same and I have  worked out an initial set of capacitor and inductor values. It looks like the brilliance boost can be done with a VTB9044 inductor but there seems to be no standard one that will do the brilliance cut. This needs values of 10, 20, 32 and 40mH. Looks like on for Chrion.

I also discovered an error in the bass cut circuit which I have fixed hopefully. Pic of simulation circuit with notes attached.

Cheers

Ian

 

[Dylan W]

I have done some simulations of the new design which confirms the brilliance boost and cut Q can be made the same and I have  worked out an initial set of capacitor and inductor values. It looks like the brilliance boost can be done with a VTB9044 inductor but there seems to be no standard one that will do the brilliance cut. This needs values of 10, 20, 32 and 40mH. Looks like on for Chrion.

I also discovered an error in the bass cut circuit which I have fixed hopefully. Pic of simulation circuit with notes attached.

Cheers

Ian

Glad to see this is coming along. How sharp did you decide to go for the brilliance Q in general?

Dylan

 

[ruffrecords]

I have done some simulations of the new design which confirms the brilliance boost and cut Q can be made the same and I have  worked out an initial set of capacitor and inductor values. It looks like the brilliance boost can be done with a VTB9044 inductor but there seems to be no standard one that will do the brilliance cut. This needs values of 10, 20, 32 and 40mH. Looks like on for Chrion.

I also discovered an error in the bass cut circuit which I have fixed hopefully. Pic of simulation circuit with notes attached.

Cheers

Ian

Glad to see this is coming along. How sharp did you decide to go for the brilliance Q in general?

Dylan

I have not measured the actual Q yet. I simply adjusted it to be visually the same as the ones you provided for me. Next job is to do that and and create a set of curves.

Cheers

Ian

 

[ruffrecords]

I spent a few hours struggling with LTspice trying to get it to step through the pot values for brilliance boost and cut  at 4.7KHz and finally bullied the  bl...y thing into submission. The results are attached. The cut is not quite the mirror of the boost but it is close. Perhaps Dylan, you would like to compare them with the plots you made of the plug-ins.

Cheers

Ian

 

[Fablab]

Hi Ian, any progress?

 

[ruffrecords]

Hi Ian, any progress?

Dylan has checked my sims against his plugin measurements and reported that the 2.7 and 10KHz curves are not symmetrical but other than that they look good.

Cheers

Ian

 

[Fablab]

Thank you Ian for what you are doing for us
Fab

 

[ruffrecords]

I have now beaten LTspice into submission and it now prints out the plots just as I want them. The following links take you to pics of the set of curves for 2.7KHz, 3.5KHz, 4.7KHz and 10KHz respectively:

http://www.ianbell.ukfsn.org/EzTubeMixer/docs/EzTubeMixer/REDDEQ/2k7plot.jpg

http://www.ianbell.ukfsn.org/EzTubeMixer/docs/EzTubeMixer/REDDEQ/3k5plot.jpg

http://www.ianbell.ukfsn.org/EzTubeMixer/docs/EzTubeMixer/REDDEQ/4k7plot.jpg

http://www.ianbell.ukfsn.org/EzTubeMixer/docs/EzTubeMixer/REDDEQ/10kplot.jpg

Cheers

Ian

 

[ruffrecords]

I have now compared the plots from the LTspice simulation with those of the plug-ins made by Dylan. The curves are not identical but they are within half a dB at the extremes of the curves and spot on in the middle (except for the 10KHz plot where the plug-in seems to peak at 9KHz.

I think that is close enough so the next step is to update the schematic and begin a PCB layout.

Cheers

Ian

 

[buildafriend]

oh man, my orange 86 project just got cooler.

 

[ruffrecords]

oh man, my orange 86 project just got cooler.

I can't seem to find a schematic for the orange 86. How are you intending to incorporate this EQ?

Cheers

Ian

 

[ethervalve]

I can't seem to find a schematic for the orange 86.

Charlie's site seems to be down. I just put my copy on dropbox: https://dl.dropbox.com/u/5567562/Orang86schematics.pdf

 

[buildafriend]

my assumption was that I could throw this post output transformer as a passive second stage within the same chassis. if you dont mind my asking, was the redd47 eq implimented differently than the way I am imagining?

 

[ruffrecords]

my assumption was that I could throw this post output transformer as a passive second stage within the same chassis. if you dont mind my asking, was the redd47 eq implimented differently than the way I am imagining?

The REDD47 EQ was implemented exactly as you imagine but it does have an insertion loss which was often made up by following it with another REDD47. Also it was 200 ohms balanced in and out.

My version is like the Helios and Pultec EQs I designed earlier in that it is intended for a 10K bridging input and needs to be followed by a dedicated gain make up amplifier. If you wanted it to be an 100% passive, no gain make up, 600 in, 600 out equaliser then that could be done by adjusting the component values but it would have about 15dB insertion loss.

Cheers

Ian

 

[drask]

Hi Ian,

Do you know wich amp is in the RS127? Tube? Germanium? Transistor?

Thank's

 

[buildafriend]

my assumption was that I could throw this post output transformer as a passive second stage within the same chassis. if you dont mind my asking, was the redd47 eq implimented differently than the way I am imagining?

The REDD47 EQ was implemented exactly as you imagine but it does have an insertion loss which was often made up by following it with another REDD47. Also it was 200 ohms balanced in and out.

My version is like the Helios and Pultec EQs I designed earlier in that it is intended for a 10K bridging input and needs to be followed by a dedicated gain make up amplifier. If you wanted it to be an 100% passive, no gain make up, 600 in, 600 out equaliser then that could be done by adjusting the component values but it would have about 15dB insertion loss.

Cheers

Ian

So a poor mans tube gain make up stage might be wise.