REDD EQ, Helios 69 and Dick Swettenham

[Sleeper]

Thanks Bruce, I checked there this morning and they had a lead time out into August...
That was for the 71 BF30 02 1 12S

But  I just searched again and I found a different part number 71BDF30-02PAJN 
with the D and the AJ standing for adjustable stops.  In stock.  ;D

 

[ruffrecords]

Have you shipped many of those Helios boards to the US?
Maybe I'll see if Hairball or Classic API would be interested in stocking up on a few... they both carry the 1p12
Do you recall what the minimum was?

1 Deck for the Helios mid...  aaahh  OK  glad I asked
I've had a few glances at the drawing, enough to confuse myself.
I'll have to draw it when I can focus.

Kelly

On the Helios, the 2 bank 12pole is for the bass switch. This really needs to be a shorting type and that is the one that is not readily available. You can probably get away with the regular non-shorting type of which the the 71BDF30-02PAJN is one version that is readily available.

The REDDEQ uses a similar bass circuit so it also needs a 2 deck 12 way switch there. It also needs a two deck 12 way for the mid boost/cut.

I have sold a lot of Helios boards the the US. In fact I have run out of the original design and only have a few of the 3U ones left. Looks like its time to order some more.

If I can get time I'll draw a quick circuit of how the Helios would look fully switched.

Cheers

Ian

 

[bruce0]

@Sleeper and Ian:

I too wanted the shorting and found them unavailable at digikey.  So I took the non shorting, which is what I think Ian used in the prototype.

Pretty much I "never" track with an EQ (if I need EQ I fix mic placement). And in mixing a small bump here and there doesn't get recorded.

(I am still drilling faceplates, so can't test yet.  I don't know the extent of the bump, or if there is one.)

I tried going direct to Grayhill and they sent me the attached email.  If you are in the US, the distributors listed may help and if you are up for for a grayhill "group buy" I would be up for it, though I only need a couple I could stock a few.  And with these little switches $500 comes up pretty fast so the minimum order is not so high really (and I have to use all these nice little grayhill cards from Ian!) so we could probably cobble together a minimum order (they quote 8 weeks, but if we are a small order in a standard range of products, I would guess they have stock lying around).

Bruce,

Hello, please note in order to purchase direct you must be an OEM
account, and we have a $500.00 order minimum.

If you can not meet this dollar minimum requirement, you may buy thru
an authorized Grayhill distributor such as, Sager,

Future, Allied, Arrow, Avnet or Digi- Key.

71BDF30-02-1-AJS        1-24 pcs      $27.02 each

71BDF30-01-1-AJS        1-24 pcs      $19.69 each

Lead time for both switches is approximately
8 weeks ARO
and are non-cancellable non-returnable

Terms Net 30 Days FOB LaGrange, IL
  Quotation Valid For 90 Days
      Quote Subject To Grayhill
        Terms And Conditions
**** Minimum Order $500.00 ****

I bought switches for a stereo version, so 6 switches, plus a couple of extra, so I was in for $180 plus shipping.  If you do decide to go direct, I would be on for a couple of shorting versions.

 

[ruffrecords]

I attach an outline schematic showing the mid section of the Helios EQ implemented with a stepped pot - it is only 12 way as that's all I could fit on the paper but it serves to illustrate the way it is wired. I also included the wiring for the stepped bass pot. Again, to save space I just did 6 steps but with a bigger switch you could do 12. There are no component values.

Conscious of the problems people are having getting hold of 2 deck 12 way Grayhill shorting switches I have shown the bass section split into two separate switches; one for the HPF and the other for the bass boost so you could use a pair of Lorlin 6 or 12 way BBM (shorting) switches instead. It also means you can do HPF and bass boost at the same time should you feel the need.

As there is not a pot in sight, I have christened this EQ the NAPIS.

Cheers

Ian

 

[Sleeper]

Hi Ian and Bruce
I've sent some inquiries out to distributors, If that works, we're on, if not than maybe we'll group buy.. .
Kelly

edit
Jeez Ian, are you sure you didn't retire because you were bored that no one could keep up with you...

 

[ruffrecords]

Jeez Ian, are you sure you didn't retire because you were bored that no one could keep up with you...

I know what you mean. I had a great career but was always doings things other people wanted me to do. Now I am retired I just do the things that interest me and I just don't seem to be able to stop. Anyway, I am enjoying myself.

Cheers

Ian

 

[Sleeper]

The postman just delivered my boards!
Thanks for that drawing.
It looks like I'm going to slow up for a tad, as I've got a lot of parts in transit. 
Onward...

 

[Gearsix]

Hello Ian, considering the high price of the Gryhill switch, is it possible to use some pots?

 

[Sleeper]

Ian and I have recently been discussing a mastering version, all switches...
the original has 3 switches and 2 pots
but
No.
Check the schematic... the different frequencies and the bass boost do their thing by switching in different LC filters.
You could make it work with 3 dollar switches, like lorlins, but you would have to hand wire it to the board. 
That's a lot more work. less money though

 

[Gearsix]

I think you are speaking about the Helios.
I am asking for the Redd Eq where at least for two switches the Lorlin can't be used

 

[ruffrecords]

I think you are speaking about the Helios.
I am asking for the Redd Eq where at least for two switches the Lorlin can't be used

As you will probably know from the very first post, the REDD EQ was designed at the request of a client. The idea was to make it as close to the original. The original used switches so this design does too.

I am of the view that the Helios was derived from the REDD design. One thing that was changed was the mid and bass boost switches were replaced by pots. So in that sense the Helios is the answer to your question.

The other unique feature of the REDD EQ is that the Q of the mid boost/cut is the same for cut as it is for boost. To achieve this requires a 2 pole switch for the mid boost/cut control. In the Helios they let the  boost Q and cut Q be different which meant you only needed a 1 pole switch. Then they replaced that with a pot and a boost/cut toggle switch which also saves on inductors. So again, the Helios is sort of the answer to your question.

The harder question is can you build the REDD EQ PCB with pots replacing some of the switches?

Starting at the top end, the 10KHz boost/cut is a switch just like the Helios. The design does not lend itself to replacing this with a pot. The mid frequency switch is off board and could be a cheap Lorlin so that's not an issue. The stepped level pot is a 2 pole 12 way Grayhill. This could be replaced by a pot and a boost cut switch effectively turning it into a Helios mid but you lose the boost/cut Q being the same. At the low end the bass switch works much like the Helios and is a 2 pole 12way Grayhill. You could hard wire a cheap Lorlin into the bass cut pads and replace the stepped boost by a pot to save using the Grayhill. This would give you separate bass cut and boost controls.

To be honest I am not sure whether it is worth it or not.

Cheers

Ian

 

[Fablab]

Hi Ian, any new from the pcb side?

 

[anjing]

I think Ian took a week off.

 

[Fablab]

Great 

 

[ruffrecords]

I am back from holiday in Sherwood Forest. While I was away the post man delivered the new REDD EQ PCBs so if you want one please email me.

Cheers

Ian

 

[ruffrecords]

16 of the 20 boards are spoken for and shipped. Only 4 left.

Cheers

Ian

 

[Sleeper]

Hi Ian,
I'm waiting to hear back from Hairball Audio.  He's contacted Grayhill, so we'll see if those switches become available in the states...

I've got some inductor questions.
No matter what, Chrion, Carnhill or Cinemag, I'm paying a good bit for the inductors and a lot of that is either shipping or design... 

David at Cinemag can wind the inductors for me, but he had a question to which I have no answer...

The Carnhill inductor called out in the schematic (VTB9042) probably is on a P2616 core.  That part number refers to the size of the core, which is important for the maximum signal level it can handle.  For this tapped 1H core, there are tradeoffs between inductance tolerance (+3% vs +5%) and the dcr of the windings and, hence, the Q (quality factor).  Note that Carnhill specifies +10%.  I need to know which characteristic is most important for this application.

I have cinemags in my pultecs and they sound great. 

Maybe I can save a bit on the 10H
I've been looking at the inductor threads, mostly pultec stuff, that's around...
as well as looking at specs from Sowter and seeing that the 10H has a DCR of 1000r
I found a thread which measured the Carnhill DCR at 738r
Don't Q and DCR combine to make the shape of the filter curve... 


The reason I ask is that I may have found some much cheaper alternatives for the 10H
most of these guys are under 10USD.
Maybe the DCR makes them unsuitable?
I recall reading you tested a bunch of Epcos B8214 inductors.
Did you like them?

This? http://www.mouser.com/ds/2/28/S4924-5105.pdf
the 106K has a min.Q  .25    DCR  137ohm    Current  54ma

And then there is something like this Hammond 157H    it's big, but
10H with a DCR at 470 ohm     
http://www.mouser.com/ds/2/177/EDB157H-222270.pdf

This Triad specs about the same.    10H dcr 500 
http://www.mouser.com/ds/2/410/C-3X-222148.pdf

Thanks
Kelly

 

[ruffrecords]

@Sleeper

I guess you are talking about the Helios EQ because the REDD EQ does not use a 9042 inductor! - it uses the 9044.

Tee P2616 core looks about right to me for the 9042 (the 9044 is smaller). Although the Carnhill inductors are specified at 10% the ones I have measured are much better than that. I suggest you ask Dave at Cinemag for 5%. The DCR of the inductor defines the maximum possible Q. In an equaliser, the DCR plus the intentional circuit resistance defines the actual Q. What you want is for the circuit to determine the Q, not the inductor so you generally arrange for the DCR to be a small fraction of the circuit resistance hence my advice to go for the lesser tolerance which presumably means lower DCR.

10H inductor. The Hammond and Triad are not suitable. They have iron cores intended to work at 100/120Hz only. They are no good for audio unfortunately.

The ones from Mouser are surface mount types and their values are in the micro Henry range. They might be suitable substitutes for the EPCOS 8214  in the REDD EQ (which incidentally sound fine - they were used in the prototype REDD EQ) but they get nowhere near 10H.

Cheers

Ian

 

[tomas1808]

What are the dimensions of the REEDEQ board?

Thanks!

 

[ruffrecords]

What are the dimensions of the REEDEQ board?

Thanks!

It is 100mm by 100mm (just under 4 inches square).

Cheers

Ian