Anyone tried Bartolini NTMB released schematic?

[ModulusMK]

I've made this preamp from the schematic that was released from one guy and it works exactly the same, very quiet and boost capable (I used exact parts except those f...up values like 25K6 resistor etc).
You can't really tell the difference between the factory made and the home made one. Boost works, Bass knob works, Treble knob works all great, BUT Mids do not work. Like the knob doesn't exists.
(now talking for the "Mids" section) In this case I'm not sure what exact kind of inductors is needed. I used what I found here (150mH each, 9 ohms serial R instead of 159R). And the capacitors are 1uF instead of 0.82uF but I doubt that they are the problem. I'm assuming the inductors.
Anybody knows what kind of inductors is used here? Or maybe something else is in question here?

Thanks!

[MarkusBass]

Can you post this schematic? You can try to guess the inductor value in a simulator program.

Mark

[ModulusMK]

I know the value of the inductor and the resistance (if except it is not a wrong value in the schematic), but used same value and different resistance. It needs to be 2 x 150mH with 79 ohms each (as labeled on the schematic), and I used 2 x 150mH 4.5 ohms (there are 2 inductors in series).

However, I haven't seen inductor with that large resistance with small value of 150mH.
So that might be a problem and I'm asking if someone has made it and the Mids are working.
The schematic is not by my hand now, will post it later.

[MarkusBass]

I don't think that with the Mid frequency filter the DC resistance of the inductor counts. But you may try adding a resistor in series.
Try any of the simulaton programs and see whether the resistance is important in this case.

Mark

[ModulusMK]

Is the basic measurement for inductors read in uH and not mH? If it's so then I got wrong inductors. I have 150uH instead of 150mH... the seller here gave me those (axial inductors, brown green brown) and after that I realized that they are read in uH?
Is this correct?

For any case I'll try to simulate.

Mark, you still want the schematic?

[MarkusBass]

I'd say that for mid frequency audio filters you need mH. E.g. Ampeg used 800mH in such a filter. Yes, I'd like to see the schematic.

Mark

[Steve Conner]

Yes, it should be millihenries and your inductors are microhenries.

I know because a 150mH inductor with 4.5 ohms DCR would be a huge thing weighing several pounds.

[ModulusMK]

schematic

I found 100mH on westfloridacomponents, so I'll buy 3 and use them in series to get 300mH. I guess it will work the same as 2 x 150mH.
Here it is:

[Steve Conner]

Another one for the collection, thanks!

FWIW, here's a tip on dealing with the inductor DCR. The inductor obviously had less DCR than the designer wanted, so he added R7 in series with it to pad it out. If your inductor has a different DCR, then you can adjust R7 accordingly.

I guess it also means that you could use an inductor with 1k DCR...

[ModulusMK]

Another one for the collection, thanks!

FWIW, here's a tip on dealing with the inductor DCR. The inductor obviously had less DCR than the designer wanted, so he added R7 in series with it to pad it out. If your inductor has a different DCR, then you can adjust R7 accordingly.

I guess it also means that you could use an inductor with 1k DCR...

No problem

I thought that too, but obviously my inductor has way much lower inductance than required... so I'll have to change it anyway and if required to tune the DCR. However thanks for the thought.

You said collection.. does it happened you to have the Aguilar? I'm searching that schematic for a long time, it's a great preamp but no luck :/