Inductors in equalizer

[Fablab]

Hi Guys
I'd like to know if it is possible to use more single inductors instead of a multi inductors (in an equalizer)
I have seen on Ebay that is possible to buy the single variable inductors really for cheap 
Thanks

 

[hobiesound]

why not? look at the gpultec schematic... a multi-tap inductor is nothing more than multiple inductors on the same bobbin. Only difference is you can't use them separately.

greetings,

Thomas

 

[Fablab]

Thank you very much Thomas!

 

[shabtek]

what value are these variable inductors you speak of?

 

[hobiesound]

@shabtek, i was wondering that myself...

 

[thermionic]

What kind of inductors are you seeing on Ebay? Are you 100% sure they'll work for audio filters? Are they ferrite core? Do you know the core size?

If they're cheap, then fine, go experiment. But, if you're planning to buy a few, be sure to ascertain that they'll work ok in your application. Saturation can introduce some pretty unpleasant distortion!


Justin

 

[bruno2000]

I've had some issues with using taps on inductors and what I believe is stray capacitance (sp?).  Using a "standard" LC circuit tuned for 2k4Hz, I get some response variation in the 50kHz region when I use a tap, but not when I use a whole inductor.
You can buy "cup" inductors in the 250-500mH range on eBay used in Wah-Wahs pretty cheap.
Best,
Bruno2000

 

[Fablab]

Thank you to all
I don't know if the inductors I have seen on Ebay works for audio filters, but I'd like to try.
I want to realize a simple but good eq with only switchable 10/12khz and 60/100 Hz controls
Any suggestion in order to inductor/caps/resistors is welcome

 

[analag]

The sound of ferrites sucks especially at LF.

 

[hobiesound]

The sound of ferrites sucks especially at LF.

then why are all the neve inductors made out of ferrite cores ? your remark seems like a generalisation. I'm particularly interested in inductors because i love the sound of good inductor eq's. I'm winding my own but have yet to finish any project with them in them (wish the day had 48 hours). I bought a big selection of different cores to experiment with. any info about good cores and even where to get smaller (ie that fit in 1HE) iron lams and bobbins in small quantitiies i would love to know.

 

[tmuikku]

Isn't these rather small?  http://tinyurl.com/ykwa4yn (Conrad choke / coil kit)

Don't know about suitability, but these were mentioned here: http://www.diygallery.de/DIYsites/inductor.html

 

[mitsos]

I want to realize a simple but good eq with only switchable 10/12khz and 60/100 Hz controls

Have you tried to find Toko inductors (used in Gpultec, and AFAIK in some manley EQ). 

For 2 Frequencies per control/switch, I think you have many ways of doing it. I don't know what the best way is of course, but you can do it with 2 single-value inductors and 4 caps.  IIRC the pultec schem shares inductor tap or caps for some frequencies. 

PeterC wound some iron core inductors for the 5003 EQ project. He hasn't shipped the EQs yet, so no one has heard them, but they should sound good.  They look to be smaller than the output trafo, so smaller than 625 EI core.  I don't know how you'd find the AL of it though.

Hobiesound, please let us know the results of your core experiments when you are done.

Are you guys all hand-winding? 

 

[hobiesound]

yeah i know, those are similar to the n87 ef25 cores i got at menting. i also have a few rm cores with n48 al400 cores which are the same as the cores used by carnhill which i have high hopes for my upcoming hi band in a api 553/opamp labs type eq. I was thinking of getting some hammond chokes rated at 10H but those are a little too big to fit in 1HE/U and i have no idea if they are gonna work/sound good. and i'd rather wind them myself so i can easily adapt the values and make a multi-tap inductor. besides i'm a big proponent of "DIY or DIE" so getting carnhill inductors kinda makes me feel dirty . Besides i want to know why certain components sound good and this way i can hear the difference for myself.  

and yeah where did peter c buy those cores !!!! i want the left overs !

greetings,

Thomas

 

[hobiesound]

Hobiesound, please let us know the results of your core experiments when you are done.

i sure will as soon as i finish the damn thing !

Are you guys all hand-winding? 

i bought a small winding machine on ebay from china. (this one http://cgi.ebay.com/LowSpeed-Coil-Winding-Machine-Winder-0-1Turn-2Direction_W0QQitemZ270553577522QQcmdZViewItemQQptZBI_Electrical_Equipment_Tools?hash=item3efe3ff832 ) It's only a stepper motor with a small micro processor for which you can set the amount of windings. very simple so i still have to guide the wire with my hands. But it's probably a perfect companion for one of those hand cranked automatic wire laying coil winders.

greetings,

Thomas

 

[sahib]

Sorry to be out of topic but just a little observation on that machine. It seems like a nice small thing but being open loop is not really a good thing. It will not be the case for winding smaller gauge wire, as the stepper would be strong enough and would break the wire if jammed, but if you are winding a reasonable higher gauge wire and a bit tough on holding the wire the motor may lose step/steps but the counter will keep on counting. It claims 0.1 turn resolution and this is the very point I am trying to make. If the stepper misses 10 of those during an entire winding you lost 1 turn. Just be careful.

 

[hobiesound]

@sahib

you're right that it count's the pulse it sends to the stepper and not the physical windings. But as a side note the motor is quite strong and i have been able to wind multi-tap inductors to within +1 procent. So not +- 1 procent which is quite good but i have yet to wind massive inductors with windings in the thousands and wire gauge above 0.3 mm so i haven't noticed any slipping yet. under 0.3 mm the wire breaks easier than that the motor slips..

greetings,

Thomas 

 

[analag]

The sound of ferrites sucks especially at LF.

then why are all the neve inductors made out of ferrite cores ? your remark seems like a generalisation. I'm particularly interested in inductors because i love the sound of good inductor eq's. I'm winding my own but have yet to finish any project with them in them (wish the day had 48 hours). I bought a big selection of different cores to experiment with. any info about good cores and even where to get smaller (ie that fit in 1HE) iron lams and bobbins in small quantitiies i would love to know.

Maybe it's the way my ears work. Even with transformers I'm partial to silicon steel. High permeability cores saturate abruptly. I think I'll go get my ears checked.

 

[hobiesound]

@ analag 

my remark was in no way ment to be a stab at you nor your ears... it was just an observation. I'm looking for explanations as to why,

greetings,

Thomas

 

[Fablab]

Do you think these inductors are ok?
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MESELX:IT&item=110360889489

 

[ChrioN]

Do you think these inductors are ok?
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MESELX:IT&item=110360889489

Are you constructing a RF filter?