The really nice analog rack EQ's from old recording studios and broadcast equipment are done this way... I have happened upon a couple such pieces of iron accidentally, in buying whole lots of vintage iron, but the high fidelity stuff is generally really pricey. It will probably be more do-able to just order brand new, custom. That won't be cheap either, but it will be possible.
Here is a page from the old UTC catalog describing such equipment:
Of course, other manufacturers also had such things. Stancor, Thordarson, Triad, etc etc. You can search "vintage equalizer" and you'll see it can be upwards of $2k for a unit with only two coils. Not very efficient. But sometimes the coils come up orphaned, and often the seller won't know exactly what it is, and it'll be like $50. What they will see is a choke with a current rating so small that it's obviously not for a power supply... Most of the buyers will be restoring priceless RCA kit or something like that... not many diy builders going after this, and if they are I would expect that it's for a recording studio application.
The ones I have are from military com gear, used for reducing noise from mics in aircraft and other noisy locations... they are UTC, but marked with a 5-digit code that doesn't correspond to any published catalog I know of.
All of this stuff is for either line-level or low-level signal sources.
Here is a page from the old UTC catalog describing such equipment:
Of course, other manufacturers also had such things. Stancor, Thordarson, Triad, etc etc. You can search "vintage equalizer" and you'll see it can be upwards of $2k for a unit with only two coils. Not very efficient. But sometimes the coils come up orphaned, and often the seller won't know exactly what it is, and it'll be like $50. What they will see is a choke with a current rating so small that it's obviously not for a power supply... Most of the buyers will be restoring priceless RCA kit or something like that... not many diy builders going after this, and if they are I would expect that it's for a recording studio application.
The ones I have are from military com gear, used for reducing noise from mics in aircraft and other noisy locations... they are UTC, but marked with a 5-digit code that doesn't correspond to any published catalog I know of.
All of this stuff is for either line-level or low-level signal sources.
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Hi abraxalito,
Thanks for your suggestion, do you remember the inductance of Murata ? I have one and I see 1,5mH that's correct ? but in the datasheet this is 0,9mH
Thanks by advance
I recall from the datasheet I turned up it was indeed quoted as 0.9mH. I don't think the precise inductance is very important in this application and normally more is better as it gives better rejection of common-mode noise. The current rating was what I went for and the suggested part is rated at 3A vs 2A for the original.
Hi my friend and thanks to you I really appreciate, the inductance get the loss insertion at one frequency I think this the most important.
Many tanks to you for your help.
Best
Many tanks to you for your help.
Best
For basic diy, Wurlitzer organ laminated core signal chokes had a manual gap adjustment for inductance setting, and came in a range of max inductances up to 4H (eg. from 4100B model).
Another form of diy inductor is from smallish relays, with the armature kept in situ - they will likely be circa 100-200mH for 12Vdc style pcb relays (eg. Finder 40.52 and Omron G2R).
More modern electronic ballasts likely have a ferrite core inductor which may be 100-200mH.
Obviously not designed for low shunt capacitance.
Another form of diy inductor is from smallish relays, with the armature kept in situ - they will likely be circa 100-200mH for 12Vdc style pcb relays (eg. Finder 40.52 and Omron G2R).
More modern electronic ballasts likely have a ferrite core inductor which may be 100-200mH.
Obviously not designed for low shunt capacitance.
You can check with them:
http://www.falco.com/Prods/PCBM.aspx
AFAIK they build those:
https://store.mesaboogie.com/products/inductor-toroidal-1h.html
Vitec al well produces them:
https://www.viteccorp.com/data/CatalogSensing.pdf
They are all current sense inductors.
http://www.falco.com/Prods/PCBM.aspx
AFAIK they build those:
https://store.mesaboogie.com/products/inductor-toroidal-1h.html
Vitec al well produces them:
https://www.viteccorp.com/data/CatalogSensing.pdf
They are all current sense inductors.
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In case you don't already know, it needs to be mentioned why no one uses actual inductors for making a graphic equalizer.
https://electronics.stackexchange.com/questions/270460/circuit-analysis-of-graphic-equalizer
And therefore, why you will have a hard time finding actual inductors for that purpose. For many values, a real inductor is virtually impossible while a gyrator is easy-peasy.
But this is 2024, so graphic equalizers are a thing of the past, and if you still want to "equalize" your sound system, the current solution is a DSP.
https://www.daytonaudio.com/product...gital-signal-processor-for-home-and-car-audio
Or better yet, use the equalizer that is part of your media player.
Less is more.
https://electronics.stackexchange.com/questions/270460/circuit-analysis-of-graphic-equalizer
And therefore, why you will have a hard time finding actual inductors for that purpose. For many values, a real inductor is virtually impossible while a gyrator is easy-peasy.
But this is 2024, so graphic equalizers are a thing of the past, and if you still want to "equalize" your sound system, the current solution is a DSP.
https://www.daytonaudio.com/product...gital-signal-processor-for-home-and-car-audio
Or better yet, use the equalizer that is part of your media player.
Less is more.