If we were living on the 40s that would be the only option.
But in the Modern World that inductor and in fact the whole XO can be made active with modern components, Op Amps and such, or worst case discrete.
Performance would be better, with a precision, lack of hum, etc. old time Engineers would have murdered for.
Never understood very much the urge to do things the old obsolete way "just because" specially when performance is guaranteed worse and actual build is "complicated", to put it mildly.
Oh well, this is DIY Audio, all styles accepted 😄
"But in the Modern World that inductor and in fact the whole XO can be made active with modern components, Op Amps and such, or worst case discrete."
I was thinking like this 10 years ealier as well. But this not true from my point of view.
I was thinking like this 10 years ealier as well. But this not true from my point of view.
Hi. Not speaker related, but I'm repairing a 1967 Vox Jaguar Organ and the Pot Core coil wires in one of the circuits have broken. The schematic (http://www.voxshowroom.com/ct/schematics/V304_Jaguar.pdf) shows the item in the Voicing card area, labeled as L2 4H. A photo of an unbroken one (not mine) is attached, and mine has a FX3238 C7K number on it. Any idea beyond the 4H what the specs on this Pot Core is? A buddy suggests it might be something in the 220 Ohm/4000mH range. Ideas on how I might repair or replace?
Attachments
The potcore is quite small for 4H, meaning it is gapless and wound with many turns of very thin (and fragile) wire. The fact that it is held together with a metal screw confirms this.
The damage is probably located at the wires terminations: the wire is thin, embrittled by the tin and corroded by by the flux.
You can gently dismantle it and remake the terminations: if the outer connection is the issue, just unwind one turn to get an unscathed section of wire, and if it is the inner connection, try to solder a small piece of wire to bridge the breakage.
If it is impossible, you'll have to unwind it completely, counting the turns, and then rewind it with fresh wire; quite a chore
The damage is probably located at the wires terminations: the wire is thin, embrittled by the tin and corroded by by the flux.
You can gently dismantle it and remake the terminations: if the outer connection is the issue, just unwind one turn to get an unscathed section of wire, and if it is the inner connection, try to solder a small piece of wire to bridge the breakage.
If it is impossible, you'll have to unwind it completely, counting the turns, and then rewind it with fresh wire; quite a chore
I am wondering ...
What is the reason for pot core inductors. For example in LCR RIAA networks a different kind of inductors is used. Why not use for example Anode chokes or other audio related inductors instead of the pot core ones? Is it just a metter of size and shilding?
What is the reason for pot core inductors. For example in LCR RIAA networks a different kind of inductors is used. Why not use for example Anode chokes or other audio related inductors instead of the pot core ones? Is it just a metter of size and shilding?
Shielding might be a factor, but they are used mainly for their stability, initial accuracy, trimming possibility if an adjustor is inserted and linearity: ferrite, especially when gapped tends to be more linear than most types of iron
I guess coils in an LCR RIAA networks have to cover similar advantages as in a passive XO or is my assumption wrong?
It depends on what you mean by passive: for some people, it is just RC circuits. LCR is passive too, but it allows higher Q, etc. just like "conventional" active circuits. By conventional, I exclude more exotic topologies like FDNR etc.
In principle, conventional active circuits can be made perfectly equivalent to LCR circuits, but LCR suffer from limitations caused by the inductors: they are inevitably lossy, and non-linear if they use a magnetic core.
If they don't, they are even lossier and become very sensitive to external parasitic magnetic fields, which can be a serious issue for low-level circuits like RIAA preamps
In principle, conventional active circuits can be made perfectly equivalent to LCR circuits, but LCR suffer from limitations caused by the inductors: they are inevitably lossy, and non-linear if they use a magnetic core.
If they don't, they are even lossier and become very sensitive to external parasitic magnetic fields, which can be a serious issue for low-level circuits like RIAA preamps
Elvee,
I do not stuck to any philosopy as only LCR RIAA or only passive XOs. I just decide by my ears, what I like and what not.
Actually I am using an active analog XO with OP-Amps to add a Sub to my speakers. But there is an audible difference between with and without XO.
So I decided to give an passive line XO an try to see how it sounds.
As I mostly use analog Music sources like turntables and a tubeamp - a DSP is from my point of view - not really an option. to many digital to analog conversions.
I do not stuck to any philosopy as only LCR RIAA or only passive XOs. I just decide by my ears, what I like and what not.
Actually I am using an active analog XO with OP-Amps to add a Sub to my speakers. But there is an audible difference between with and without XO.
So I decided to give an passive line XO an try to see how it sounds.
As I mostly use analog Music sources like turntables and a tubeamp - a DSP is from my point of view - not really an option. to many digital to analog conversions.
Probably old news, but second-order Linkwitz-Riley filters can be approximated fairly closely with a passive RC filter if the source impedance is much lower than the load impedance and if the source can drive a lowish-impedance filter. It's not an exact Linkwitz-Riley you get that way, but spproximating it to within 1 dB is no problem.
Second- or higher-order Butterworth filters and higher-order Linkwitz-Riley filters do require inductors if they are to be passive.
Second- or higher-order Butterworth filters and higher-order Linkwitz-Riley filters do require inductors if they are to be passive.
I suspect that the preference for L-including building blocks as well as the "tube" sound is mostly attributable to the "magnetic" coloration of the sound: the magnetic core imparts mostly two types of distortion. One is caused by the hysteresis, and is expansive. The other is compressive and is caused by saturation.
The gentle combination of both seems to create a sound signature pleasant to many hears. OTL's by contrast do not seem to generate the same kind of enthusiasm, despite their objectively better performance when properly implemented. They are just another variety of "semiconductor" based device, although they do not use solid state devices
Elvee, on the sound signature you may be right. But this does not explain a different 3-D imaging.
Hi Everyone,
I have the Marchand XM46 and I'm trying to modify (reduce) the inductances. I thought that it would be as easy as removing a few turns from the coil... but it seems that these things must be glued together.
Would anyone have any ideas on how to open these?
I have the Marchand XM46 and I'm trying to modify (reduce) the inductances. I thought that it would be as easy as removing a few turns from the coil... but it seems that these things must be glued together.
Would anyone have any ideas on how to open these?