REDD EQ, Helios 69 and Dick Swettenham

Strawtles said:

Do you think to realize a "pro" PCBs like your other projects or only the gerber files?

Click to expand...

Actually, I am quite intrigued by this EQ. Once I am happy with the layout I will definitely have some made. Then, if there is enough interest I will make them available here.

One reason I am intrigued by it is that, on the journey that led to the final circuit, I had a design that quite neatly made a fully switched Helios 69 EQ - not a pot in sight. It occurred to me that stereo version of that would make quite a good mastering EQ.

Cheers

Ian

Do you know if there are differences between the Chrion inductors and the Carnhill ones?

Strawtles said:

Do you know if there are differences between the Chrion inductors and the Carnhill ones?

Click to expand...

I am sure there are differences but I guess you mean any differences that affect the sonics. The answer is I do not know as so far I have only used Carnhill ones.

Cheers

Ian

I can't wait to see this circuit 
In the meantime, it is possible to know the value of the components?
So we can begin to search them!
Best

Strawtles said:

I can't wait to see this circuit 
In the meantime, it is possible to know the value of the components?
So we can begin to search them!
Best

Click to expand...

The current circuit is here:

http://www.ianbell.ukfsn.org/EzTubeMixer/docs/EzTubeMixer/REDDEQ/MKIIV2circuitscaled.jpg

Most but not all of the component values are correct. I am in the process of putting together a BOM for it.

Cheers

Ian

If the values are not definitive, I think it's better to wait you complete the project

Strawtles said:

If the values are not definitive, I think it's better to wait you complete the project

Click to expand...

They were only uncertain when I drew that circuit. The main uncertainty was around the capacitor values in the brilliance boost/cut and the inductor values in the brilliance cut circuit. Now that I have selected the brilliance cut inductors and built and tested that part of the circuit, those values are firm.

So, I have put together a preliminary BOM which you can find here:

http://www.ianbell.ukfsn.org/EzTubeMixer/docs/EzTubeMixer/REDDEQ/AssyIns.pdf

It will at least help you to identify the long lead time items. There may be minor resistor and capacitor value changes after I test the first PCB.


I am more concerned about the PCB layout. I have checked it three times now and each time found a major error/omission so that is what I am going to concentrate on.

Cheers

Ian

I have seen in the schematic that there is a 10khz filter in the brilliance control, too
It has a different shape or it is the same of the High control?

Do you think to realize an adaptor to use Lorlin switches instead of Grayhill?
The Lorlin are chaeper and I use them from many years without problems
This mod may be useful for those who want to realize more modules (8 or 16) for a custom mixer

Strawtles said:

I have seen in the schematic that there is a 10khz filter in the brilliance control, too
It has a different shape or it is the same of the High control?

Click to expand...

Yes, the 10KHz brilliance boost is the same shape as the 'Pop' EQ in the REDD 47 - in other words it is a peaking response. The treble control is shelving at 10KHz just like the 'Classic' EQ in the REDD 47. So you can have either with this EQ.

Do you think to realize an adaptor to use Lorlin switches instead of Grayhill?
The Lorlin are chaeper and I use them from many years without problems
This mod may be useful for those who want to realize more modules (8 or 16) for a custom mixer

Click to expand...

The problem with that is that two of the switches are 2 pole 12 way types and as far as I know Lorlin does not make one like that. The treble control is a 1 pole 12 way so a Lorlin could be used there. The brilliance switch is not on the PCB. I have brought its connections out to a 16 way header which is compatible with the Lorlin and Grayhill adapter PCBs I have designed for the Unversal EQ. So you can already use a Lorlin for that switch. You could also use it for the 1 pole 12 way treble switch by wring from the Lorlin adapter board direct to the Grayhill pads on the PCB.

The Lorlin adapter PCb first appeared here:  http://www.groupdiy.com/index.php?topic=50484.msg650062#msg650062

Cheers

Ian

I have added the pad to the PCB to facilitate EQ IN/OUT switching and done a few more tweaks and changes. I think it is just about there now. I will check it once more then commit to production of some prototypes probably at the end of the week.


Cheers

Ian

Hi Ian,
I am considering that using the Lorlin switch with your adapter may be difficult in a API format project.
It is possible for you to post the way to connect the leads directly to the pins of the Lorlin switch?
In this way it is possible to save precious space on the front panel
Thank you

Strawtles said:

Hi Ian,
I am considering that using the Lorlin switch with your adapter may be difficult in a API format project.
It is possible for you to post the way to connect the leads directly to the pins of the Lorlin switch?
In this way it is possible to save precious space on the front panel
Thank you

Click to expand...

I am assuming you mean for the frequency selection switch. I will draw and post a sketch.

Cheers

Ian

Yes, the switch that is out from the board
Any comment about how is the sound in your tests?

Strawtles said:

Yes, the switch that is out from the board
Any comment about how is the sound in your tests?

Click to expand...

Here you go:

http://www.ianbell.ukfsn.org/EzTubeMixer/docs/EzTubeMixer/REDDEQ/LorlinWiringscaled.jpeg

I have not built the complete EQ so I have not made any listening tests yet. I plan to order some prototype PCBs this week and build one when they arrive.

Edit: here's what I hope is the final PCB layout:

http://www.ianbell.ukfsn.org/EzTubeMixer/docs/EzTubeMixer/REDDEQ/REDDEQApril11th.png

Cheers

Ian

Thank you!

I just the order for some prototype PCBs.

Cheers

Ian

I think there are many people (like me) that are waiting to know how it sounds
have you made modifications in the component list?

Strawtles said:

I think there are many people (like me) that are waiting to know how it sounds
have you made modifications in the component list?

Click to expand...

I am going to build one when the PCBs arrive and listen to it. Then I will decide if I think any components need to be changed.

I started this thread because the Helios 69 EQ, designed by Dick Swettenham, has a lot of similarities with the EMI EQ and Dick worked at EMI before he designed the Helios EQ.

The brilliance boost is very very similar to the Helios mid boost and I know that sounds really good. The brilliance cut is like the Helios mid cut but arranged for a much gentler Q so I expect it will sound quite different. The top cut/boost is again very similar to the Helios 10KHz cut/boost - the only difference is the cut is shelving whereas the Helios is not. So again I expect it to sound similar but gentler.  The bass cut is again similar to the Helios but it is shelving whereas the Helios is not, so once more it should be gentler.The bass boost is quite different to the Helios so I have not heard that yet but it is a shelving EQ rather than a peaking one as in the Helios.

Overall I guess I expect it to sound gentler all round which could be rather interesting.

Cheers

Ian

Hi Ian, any progress?

Strawtles said:

Hi Ian, any progress?

Click to expand...

PCB has gone to manufacture. I am trying out a new PCB company. They are a Chinese family living in England who still have a factory in China. Boards should be here in a couple of weeks.

Cheers

Ian