NYD's passive EQ, ghetto edition

[NewYorkDave]

Hey, some interesting pot cores...

http://www.cwsbytemark.com/prices/pot.php

 

[Learner]

[quote author="NewYorkDave"]Well, it looks like the dream is dead unless I can find a supplier of high-L, high-Q inductors in small quantities. I got a quote from Wilco today, and there is no way I can meet their minimums without taking out a bank loan. :sad:[/quote]


Came across this ad, looks like it might be worth a try....

Custom Wound Components

 

[mik]

Dave, I'm buisy at the moment, but wen I 'll free I try to wind some indictor, Just let me know values. or 2nd option: try contact Cinemag David he's a cool Guy, I'm sure He can understed.
Let Me know
Mik.

 

[Rochey]

[quote author="skipwave"] will do anything I can to help, including buying the kits even if I could manage without them. I would happily pay a hefty markup to get a complete set of parts in a baggy and a set of directions written in Dave's humorously irreverent style.

Again, I'm just thinking out loud while typing silently. I genuinely would like to see Dave go into business and would support such an effort just on principal.[/quote]

Completely agree -- I'd like to see "kits" of that nature for all the designs we see on here. Either that or a "deal" with mouser or someone where there's a parts list ready to go, deliverable within 48 hours

 

[smallbutfine]

I second that Rochey :thumb:
In fact i'm interested in the original designs on this board because i want to learn how this gear functions in detail and build them for my small studio. I try to follow the steep learning curve out of intellectual and not commercial interest. Otherwise i am absolutely for the possibility of everyone to commercially use his own designs without having to fear a ripoff.
The sad side of this is your (respected) conclusion, Dave. So as long as you do not make your designs commercially available, we are screwed in some way...
But I really appreciate the possibility to get your designs per email.

A kit for this one would greatly be welcomed by a lot of people here...

Kind regards

Martin

 

[Rochey]

Dave, a thought for you...

having those hard-to-find parts is a good thing in these designs - surely the likes of Behringer would find it hard/expensive to find those parts as well? Folks on this board wouldn't mind shelling out $20 for a single part if other parts were relatively cheap - but someone like the big B would hate it - imagine having that much stock sitting around?

Also, I really wouldn't worry about the boutique guys - they will make a few handful's of units per year. In fact, if you had the kits ready (parts and pcb) they would probably buy them from you directly and custom build from their clients. Essentially, that makes you into a manufacturer, and them into your distributor.

Finally, a question that pops into mind is:
is there a way of making these designs difficult to mass produce, so that the big B, or some chinese rip-off artists can't take the design and produce hundreds, possibly thousands of them?

Cheers

R

 

[NewYorkDave]

The cost/availability of the low freq inductors wouldn't stop someone like Bear Ringer; I think they have enough capital to meet the minimum orders :wink:. Actually, they'd probably keep the high frequency section of the circuit and make the rest active, and they'd still have the nerve to call it a "passive EQ" because at least part of it was passive--kinda like how they can drop one tube into a sea of ICs and call it a "tube preamp" or whatever.

But really, despite my initial worries about Chinese ripoffs, I've come to realize that it's really wannabe boutique guys who pose a threat.

 

[mik]

I am a "wannabe boutique guy", but only after your permission and royalty agreement. :sam: :sam:
what about a "pay in advace" for the kit option ??
M.

 

[NewYorkDave]

I have to give some thought to the whole kit thing. Remember, this was an idea that everyone else cooked up for me, I never expressed a desire to do it. Really, I'm mostly interested in producing finished units. Kits are cool, but I work a full-time job already and my limited free time might not be best-spent on tech support for something with such a low profit margin. But I'm not ruling it out completely!

 

[edanderson]

[quote author="NewYorkDave"]I really only need three large values that are hard to get. For the smaller values in the high freq. band, the Fastrons work just fine.
[/quote]

i assumed that you actually chose the two largest L values because they matched two of the values from the xicon transformers (as inductors) from mouser. is the DCR too high?

ed

 

[NewYorkDave]

Glad you brought that up. The Xicons measured OK for DCR and for inductance on the quickie-checker (which tests at 100Hz or 120Hz, can't remember which). But when used in the tuned circuits in my EQ, they totally sucked. They resonated at the wrong frequencies, had horrible Q figures, etc.

I didn't really pick the values to match the Xicons, anyway. The values were chosen to give a desired bandwidth with the impedances involved in my circuit. But it seemed awfully convenient that a couple of the Xicons were right around the correct values. It's a shame it didn't work out, 'cause they were pretty cheap.

 

[mik]

Dave to producing finished unit need more time and maney then you think. you' have to involve many conpany for the anclouser, for silksreen for knob, you have to do machanical plan, PCB drawing...
a lot of work, belive me.

M.

 

[smallbutfine]

seems to go no way else as stupidly wire them by hand...
I will make a short order to get the conrad inductor parts Steffen used for the Blutec...
Sorry, germany, don't know sources in the us.

Fine design, dave. :thumb:
Thanks alot!

Kind regards

Martin

 

[edanderson]

dave-

yeah, i figured that was the case with the small xicon transformers. i have some of the same ones, and the L values i measured were substantially lower than what you reported. but inductance is a complex measurement, so i didn't know if the conditions you measured under were a better match for your eq circuit.

anyway, for the largest value inductor, even the wilco BSL series lists a DCR a few ohms over your upper limit. a custom part really does start to look like the only way to go.

for those that want to wind their own pot-core inductor here in the states, try this kit (intended as a wah inductor):

http://www.smallbearelec.com/Detail.bok?no=368

winding instructions posted here:

http://www.arielfx.com/inductor_guide/guide.htm

it looks like hitting the highest value with a low enough DCR should be no problem. and hey, while you're at it, pull off taps for the lower values as you go and you have a one part solution. not bad if you can invest the time.

ed

 

[NewYorkDave]

the largest value inductor, even the wilco BSL series lists a DCR a few ohms over your upper limit

Yeah, that's why (if you look at the actual measured curves I posted earlier) the 40Hz range doesn't quite achieve the full nominal range of boost and cut. But it does come close enough to be acceptable.

for those that want to wind their own pot-core inductor here in the states, try this kit

Looks interesting. Do you have a link to data on the core (AL value and such?).

Here are some other pot cores I was checking out, #77 material:
http://www.cwsbytemark.com/prices/pot.php

The tech guy at Fair-Rite seemed to think that #75 or #78 was best for this application, though. I have to research this further.

I thought about just getting some toroid samples from Fair-Rite, but winding hundreds of turns on a toroid by hand is a more tedious task than I'm willing to undertake just to save a few bucks. The pot-cores should be much easier to wind.

pull off taps for the lower values as you go and you have a one part solution.

That's exactly what I was planning to do, if I went the custom route.

 

[analag]

http://www.universal-radio.com/catalog/misc/amidonT1.html
http://www.universal-radio.com/catalog/misc/amidon.html

 

[Mlewis]

i'm really glad this thread is turning out optimistic, i just read it from start to finish and feel a bit exhausted!!

this is just my 2 pence but i think that although kits would go down a storm here, your average joe would treat them with nothing but suspicion. we all know that NYD knows his stuff but most of the music tech buying public don't and couldn't care less about inductor core material or SRPP output topologies.

if you want to make more than just a little money, you need to sell finished products and they need good reviews from either magazines or well respected users ie. well known producers/guitarists/whoever.

You've mentioned that you have no money to invest so you could do with an investor. who you get to invest (and i wish i had the finances to do this myself) will denote the scale of your company.

If i were in your position i would possibly start a registered company and sell 49% of the shares to the likes of us for however much you need to set this thing up (of course choosing people with varying skills that would be useful to your company would be sensible). then i would hire another company with an impecible reputation and with medium to small sized manufacturing capabilities to buid the units (much like G*M*L do at M*nley).

you could then keep your day job and if thing take off, hire me as manger to take care of things!!! :grin:

hope this works out for you

Mark.

 

[jeth]

Has somebody by the way noticed who many lurkers we have around? Sort the memberlist by posts and get surprised. I'm a regular in some other forums, too, but I've never seen so many passive members and so few very active members in one place.

Just thought I'd come out of the dark and add myself to the list of lurkers...Sadly i find too often that those with the knowledge want to pass it only to others at their level; it can be very hard to learn DIY audio. I just want you to know that like many others I'm sure, I'm here to lurk'n'learn, not to rip off other folks designs...I do understand NYD's standpoint but it's a shame....
I only wish I had the knowledge to post something useful to prove my worth!

 

[NewYorkDave]

I emailed Small Bear for more details about the pot-core (e.g., core size and material). I'm also going to buy one of those old-style hand-cranked drills and try to kludge it into a manual coil winder :grin:.

 

[alk509]

I just bought three different size #77 pot cores from that CWS ByteMark link someone posted earlier... More information forthcoming as it becomes available.

Peace,
Al.