DIY Hell..S.... EQ? Phaeton Son Of Hellios! FIRE!!!Let's do it!

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Igor

Well-known member
Joined
Jul 17, 2006
Messages
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Location
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As far as I know, there's no any legal issues with it :)

Sooo....I will have some time this weekend to start PCB design.

Need some input from you, lady's and gents.

My guess is:

Choice of input transformers for mic pre;

Same mic input amplification stage like used in older consoles (3-transistor's circuit);

Optional DI (HI-Z buffer) before input transformer;

RM-8 or RM-10 layout for HF inductor;

AFAIK the LF inductor originally done on iron or nickel lamination, small size core like EI-24...
if someone can put lite on this?

As line out amp, I'd used prooven second half of BA-283....fat, Class A, etc...
This will make actually a bit different thing, not like already commercially available
and will reduce headache caused copy-paste-righters....etc.

Insert after micpre? Line input option?

And, replacement for Elma switch to something cheaper, as well as (maybe) use of Lorlin switches+resistors
instead of potentiometers?

Your input wellcome. I think this can be really nice project.

Ah, yes....just a thought....Lunchbox format card wit EQ only????


schem_V69-1973-1-Var-1.jpg
 
I think this might be a little too contentious.

Helios gear IS in current production, and Tony Arnold (in Europe) is known to visit forums such as this and voice his opinions.

If a version was attempted, I'd suggest some considerable changes and a COMPLETE avoidance of the term 'Helios'. It is a registered trademark and will bring down quite a lot of trouble, I've little doubt.

Keith
 
LOL, I'm very interested. I've got a pcb layout for those amp cards and two sowter lustraphone copies waiting to be used. i even bought a small coil winding machine and i was just about to order some formers and core to try winding that low freq inductor. 

Greetings,

Thomas
 
i simulated the schematic a few months back with the values from various schematics and i got a value of 10H (this was confirmed in one of the posts here IIRC). I can't run the sim right now coz i'm at work so i don't know what the value is for the mid-band. But IIRC the mid-band inductor got varied in quite a few versions so there's no telling what the actual values were but i remember the values for the 2 tap inductor in one of the versions was more or less correct but i was planning on winding an inductor with more than 2 taps to match the values of the styroflex i have lying around.  

for people that want more info i suggest searching the B-B-B-Big helios picture thread on Pro Sound Web. I'm still looking for the schematic that was posted on vintageking for the 2004 helios reissue, i found the first page, but if anyone has the other 2 pages could they be so kind and email it to sureshotstudio -AT- gmail -dot- com .

greetings,

Thomas
 
SSLtech said:
I think this might be a little too contentious.

Helios gear IS in current production, and Tony Arnold (in Europe) is known to visit forums such as this and voice his opinions.

If a version was attempted, I'd suggest some considerable changes and a COMPLETE avoidance of the term 'Helios'. It is a registered trademark and will bring down quite a lot of trouble, I've little doubt.

Hmm. I agree about the name and i don't think the schematic should be posted. 

But, there are many in-production projects going on here. What's different about this? Why can't Igor do a H*** type? Others do other type's? The only reason there would be a problem is if TA had a fit (uh oh, being such a small project and totally modified) and that would be a real downer.. Sheesh. Besides, this would be a great addition to the 51x release! :)

Let's party!! Champagne?

I think Tony should helping us out!? He can have some champagne too?  :D

 
In case you wound inductors youself, $20 max for pair.
In case someone else do it....$40-50 maximum for pair of inductors.
 
Ahem. Little by little. For now, I just have incomplete PCB design on my laptop
and waiting for oppinions etc.
 
Mabye Carnhill inductors from Audio Maintenance would be a good option. VTB 9043 for the bass, and VTB 9048 for the midrange. ca. 34€
Its hard to get the Bass cut/boost done without a expensive rotary, unless you limit the choice to two cut and three boost steps (read lorlin 6x2)
j
 
Some info: http://cms.orphanaudio.com/forums/viewtopic.php?t=136&sid=d4fd1c008b499f33f5c201d359597575
 
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