rafafredd
Well-known member
master CJ made some BIG toroids.
NYD eq (was: gain block for a passive EQ)
- Thread starter TomWaterman
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NewYorkDave
Well-known member
For my EQ, you'd only need to make two tapped inductors: 820mH/270mH, and 100mH/33mH. Tokos/Fastrons will work for the rest of the values.
http://electronicdave.myhosting.net/miscimages/passive-eq2b.gif
As for who made the toroids, I was thinking it was some dude in Deutschland... But I remember CJ made some toroids, too.
http://electronicdave.myhosting.net/miscimages/passive-eq2b.gif
As for who made the toroids, I was thinking it was some dude in Deutschland... But I remember CJ made some toroids, too.
G
Guest
Guest
I did some experiments with winding small inductors using ferite cores from http://www.goldmine-elec-products.com/products.asp?dept=1050
I used the medium size torroids with best results. Only a hundred or so windings for a few hundred mH. I followed CJ's method of wrapping wire around a popsicle stick and threading it through the core. Simple and very effective.
I used the medium size torroids with best results. Only a hundred or so windings for a few hundred mH. I followed CJ's method of wrapping wire around a popsicle stick and threading it through the core. Simple and very effective.
NewYorkDave
Well-known member
They don't post permeability specs for those cores. How were you able to calculate your turns? Did you wind on a few turns of wire and measure in order to deduce the AL value, or did you just cut 'n try till it came out right?
I've wound my own RF inductors, but I've never tried it at audio frequencies. It could be fun... or a total pain in the ass... or both :razz:
I've wound my own RF inductors, but I've never tried it at audio frequencies. It could be fun... or a total pain in the ass... or both :razz:
G
Guest
Guest
I did the method described by PRR. Wound 10 turns of wire and measured to find AL. I did it on a small inductance meter for a quick determination. I don't have my scratch paper I did calculations on, but I got a few of each of the cores at that site on one of their sales and treid them all. The medium size (5 for $1) had the highest AL and was easy to wind.
NewYorkDave
Well-known member
So Thomas, what kind of inductance values were you able to achieve, with how many turns and what gauge of wire?
G
Guest
Guest
Damn. You're gonna do it aren't you. I was saving my last good nueron but now I have st use it to think about what the devil I did.
OK, I'll see if I can dig up something from notes or remeasure and get back to you.
OK, I'll see if I can dig up something from notes or remeasure and get back to you.
G
Guest
Guest
I measured 4 of the little torriod cores as follows:
10 turns of 30AWG magnet wire spaced snuggly around the core. Measured with Wavetek meter (with a fresh battery) at 1.105mH, 1.216mH, 1.221mH and 1.167mH. I averaged that to 1.177mH and calculated the average AL:
AL=L/N**2
AL=1.177mH/10**2
AL=1.177mH/100
AL=11.77uH
Not bad for small inductors to use in EQ's and such. They measure about 25mm OD and 12mm ID. Big enough for my clumsy hands to work with and small enough to fit easily in a circuit.
10 turns of 30AWG magnet wire spaced snuggly around the core. Measured with Wavetek meter (with a fresh battery) at 1.105mH, 1.216mH, 1.221mH and 1.167mH. I averaged that to 1.177mH and calculated the average AL:
AL=L/N**2
AL=1.177mH/10**2
AL=1.177mH/100
AL=11.77uH
Not bad for small inductors to use in EQ's and such. They measure about 25mm OD and 12mm ID. Big enough for my clumsy hands to work with and small enough to fit easily in a circuit.
NewYorkDave
Well-known member
Here's the guy I was trying to remember earlier... Steffen Mueller.
http://home.t-online.de/home/micro.wave/inductor.html
http://home.t-online.de/home/micro.wave/inductor.html
G
Guest
Guest
That's the page I got from a link on Kev's site that got me thinking about winding an inductor.
NewYorkDave
Well-known member
The DC resistance of the "PC" series is too high. I know this because I bought some samples a while ago. Remember, source and load impedances are fairly critical in just about any passive EQ. Winding resistances in a transformer appear in series with the reflected impedances and create losses.
The Edcor WSM10K/600 would be a better choice for the input. The DCR on that one is about 200 ohms/50 ohms. For the output transformer, any good quality 600:600 job should do (such as the WSM600/600).
The Edcor WSM10K/600 would be a better choice for the input. The DCR on that one is about 200 ohms/50 ohms. For the output transformer, any good quality 600:600 job should do (such as the WSM600/600).
NewYorkDave
Well-known member
That's great, J. What are you using to drive it? It must have a rather low output impedance if you're getting satisfactory amounts of boost with no stepdown input transformer. Have you made any measurements?
I'm surprised that you haven't needed makeup gain. Even without a stepdown transformer, the loss at the "flat" setting is 10dB. Are you driving it with a hot signal? Watch out for inductor saturation! :wink:
Did you use the same resistor and cap/inductor values I posted earlier in this thread?
Lastly, how about some pics? :green:
I'm surprised that you haven't needed makeup gain. Even without a stepdown transformer, the loss at the "flat" setting is 10dB. Are you driving it with a hot signal? Watch out for inductor saturation! :wink:
Did you use the same resistor and cap/inductor values I posted earlier in this thread?
Lastly, how about some pics? :green:
NewYorkDave
Well-known member
Man, you make me want to build one myself! You're going to be at least the second person who has built this before I've had a chance to make one of my own. Of course, you guys are doing me a big favor by testing my design for me :green:
I bought all the parts a while ago--I just have not had the time.
Did you use Wilco inductors?
I bought all the parts a while ago--I just have not had the time.
Did you use Wilco inductors?
tardishead
Well-known member
As I have quite a alot of Neve equipment I want to build a NYD eq in a style close to 80 series Neve equipment. I will use a step down 10k:600r Neve transformer then the passive NYD circuit followed by a BA283 line amp (maybe just the 2nd driver section)
I have 2 old 70s graphic eq units which are very close to Urei 527 - the faders are all a bit crap so I was going to scrap them for parts. They have lots of nice inductors in them to use on the NYD eq. I need to know what DC resistance to expect and what would be too much. check the inductors and see if they are applicable.
I have searched through the thread but forgive me if I ask obvious questions. The difference between Bluebird's and NYD schematics seems to be different resistors in the attenuator section. This is to apply to 600r impedance on NYD and 1k on Bluebird's design - I think I have that right.
For this type of EQ is it possible to increase the available gain at frequencies or is this limited to +10db boost -12db cut?? What about +15db boost -18db cut - is it possible?
I also have plenty of original Mullard mustard caps to keep the Neve flavour.
I have 2 old 70s graphic eq units which are very close to Urei 527 - the faders are all a bit crap so I was going to scrap them for parts. They have lots of nice inductors in them to use on the NYD eq. I need to know what DC resistance to expect and what would be too much. check the inductors and see if they are applicable.
I have searched through the thread but forgive me if I ask obvious questions. The difference between Bluebird's and NYD schematics seems to be different resistors in the attenuator section. This is to apply to 600r impedance on NYD and 1k on Bluebird's design - I think I have that right.
For this type of EQ is it possible to increase the available gain at frequencies or is this limited to +10db boost -12db cut?? What about +15db boost -18db cut - is it possible?
I also have plenty of original Mullard mustard caps to keep the Neve flavour.
NewYorkDave
Well-known member
Sounds like a good plan.
I posted this earlier in the thread, but here it is again for reference:
You can use the inductance and DCR values in this chart as a general guide. Note that the DCR values listed are suggested maximums.
Not without recalculating all the resistors in the voltage divider section... which was a very tedious exercise in the first place and not one I'm willing to repeat anytime soon. :?
Mendelt
Well-known member
I'm trying to design my own passive eq based on some transformers and line-amps i got from a PM1000. I still have a couple of questions.
Why is the Rload in most passive EQ's 600ohms? Is this an optimum value somehow? I was thinking about increasing it a little so the input impedance can be a little higher.. less trouble with wimpy outputs from other equipment and cable capacitance and stuff. Is this a good idea?
How do you get the optimum L and C combinations for a certain frequency. I understand that 270 mH and 1.5 uF will cause a peak at +/- 250 Hz. But why not 0.75 uF and 540 mH?
What are optimum values for bandwidth?
When will the filters start ringing?
Or is this just a question of experimentation?
Why is the Rload in most passive EQ's 600ohms? Is this an optimum value somehow? I was thinking about increasing it a little so the input impedance can be a little higher.. less trouble with wimpy outputs from other equipment and cable capacitance and stuff. Is this a good idea?
How do you get the optimum L and C combinations for a certain frequency. I understand that 270 mH and 1.5 uF will cause a peak at +/- 250 Hz. But why not 0.75 uF and 540 mH?
What are optimum values for bandwidth?
When will the filters start ringing?
Or is this just a question of experimentation?
tardishead
Well-known member
thanks Dave
its a real shame because the old graphic EQ that I wanted to raid for inductors - the inductors have a greater DCR than what Dave specifies.
is it because it is used in a higher impedance circuit?
is there a way I can use inductors with higher DCR if I raise the impedance of the EQ unit. I am totally in the dark when it comes to impedance. I dont understand why a 10k:600 would present the same impedance as just a straight 1:1 transformer - or is it all about the input impedance of the amplifier after the EQ stage?
its a real shame because the old graphic EQ that I wanted to raid for inductors - the inductors have a greater DCR than what Dave specifies.
is it because it is used in a higher impedance circuit?
is there a way I can use inductors with higher DCR if I raise the impedance of the EQ unit. I am totally in the dark when it comes to impedance. I dont understand why a 10k:600 would present the same impedance as just a straight 1:1 transformer - or is it all about the input impedance of the amplifier after the EQ stage?
tardishead
Well-known member
excuse me if I have missed some maths but how do you calculate what inductor to put in series to ground on the NYD EQ to create a high pass filter at different frequencies?
http://www.opamplabs.com/cfl.htm
