Giskard Charge-coupled 3145 crossover network iron core inductor source

[tjm001]

I was kicking around the idea of building one of these for a 4345 DIY project. But where in the world would one find 5.4 and 4.8 mH iron core inductors?

[JeffW]

Parts Express has 5.5 and 4.7 iron cores, just the first place I looked.

You could bi-amp them and do away with the larger coil (is it 5.5 or 6.4? I can't tell for sure).

Edit: I blew it up and that bigger one is 6.4mH

[JuniorJBL]

You can also get bigger and unwind it.

[tjm001]

Parts Express has 5.5 and 4.7 iron cores, just the first place I looked.

You could bi-amp them and do away with the larger coil (is it 5.5 or 6.4? I can't tell for sure).

Edit: I blew it up and that bigger one is 6.4mH

I should have been more clear in my original post. Parts Express was the first place I looked at before I posted and like you said they have 5.5 and 4.7 mH. But the schematic (it's a little fuzzy) states 5.4 and 4.8 mH. Close, but no cigar. Just thought with the many, many posts about this particular crossover someone hopefully knows where to get them. Thanks.

Tom

[Baron030]

If you can't find a coil with the required inductance value then order a coil with a slightly higher inductance value and then remove a few windings from it. But, it will require you to have an inductance meter.
Fortunately, the cost of Digital LCR Multimeters has come down a lot.

A quick source on amazon turned up the following for under $40.00:
"MASTECH MS8269 Handheld Digital Multimeter LCR Meter Resistance Capacitance Inductance & Temperature Tester"

And if you question the accurately of such a cheap LCR meter than you can always calibrate it by taking a reading of a coil before you remove any windings from it.

And if you have no long term need of a LCR meter then you can always sell it after the 3145 networks are built.
I would think that you could find a buyer for slightly used LCR meter right here on this site.

Baron030

[JeffW]

I should have been more clear in my original post. Parts Express was the first place I looked at before I posted and like you said they have 5.5 and 4.7 mH. But the schematic (it's a little fuzzy) states 5.4 and 4.8 mH. Close, but no cigar. Just thought with the many, many posts about this particular crossover someone hopefully knows where to get them. Thanks.

Tom

I still think it says 6.4, but that's just my opinion. And there's just 2% difference between 5.5 and 5.4, likely much closer than the tolerance of the capacitors.

Edit:

OK, here's his post with the list, I stand corrected, 5.4 it is:

http://www.audioheritage.org/vbullet...l=1#post324116

[Earl K]

Here's a repost ( from Heather ) of Giskard's original BOM ( for the 3145 ).

[JeffW]

Looks like she got 5.4, as well. That schematic sure has a 6 looking 5 in it.

[tjm001]

OK I've been studying the old posts http://www.audioheritage.org/vbullet...upgrade/page14 and http://www.audioheritage.org/vbullet...-modifications for several days now. These are excruciating detailed and drawn out communications over a long period of time back in 2005 between mainly a French guy in Canada (BandKMan) and others mostly (Ian Mackenzie) and others about crossovers for 434x systems with 4313B. I am enlightened and much more informed after reading these strings. I also think I now better understand 4313B's reaction to my post last year questioning Charge Coupled Crossover Networks. Sorry I stumbled into this about 10 or more years after the fact! But I am not a troll. I was and still am an innocent and honest bystander at the wrong place at the wrong time when I questioned Charge-coupled crossovers.

It seems obvious to me from reading all this is that the way to go on a 4345 DIY crossover is the bi-amp option. My problem is I'm from the old school of what electronics were back in the 1960's. I studied and was well versed with all the Capacitor/Inductor stuff back then, but my career path led me in an entirely different direction (Air Traffic Control and Law Enforcement). Other than the Nelson Pass crossovers I built for my L300s last year, I haven't fooled with this stuff since the late 1960s. I'm still into the Amp, pre-amp and passive crossover mode. So I'm a little shaky on the bi-amping.

I am confident I can build Cross-coupled crossovers for my 4345 project with minimal advice. My question at this point is, if I go bi-amp or even tri-amp as Greg Timbers recommends for the 2405, do I just follow the schematic eliminating the LF and UHF legs of the schematic? My instinct tells me there is more to it.

[Earl K]

Hi ,

If you bi-amp; eliminate all the passive components within the section bounded by the dashes .

If you tri-amp ( as per GT's advice for adding an amp onto the UHF ) then do as above but also eliminate all the passive components in the UHF leg ( personally, I'd still include the variable Lpad for ease of component balance ) .

[tjm001]

Hi ,

If you bi-amp; eliminate all the passive components within the section bounded by the dashes .

If you tri-amp ( as per GT's advice for adding an amp onto the UHF ) then do as above but also eliminate all the passive components in the UHF leg ( personally, I'd still include the variable Lpad for ease of component balance ) .

Thanks. This helps. I'm beginning to get the picture. I need to bone up on the equipment that goes before the amps now. Any suggestions?

Tom

[Earl K]

Thanks. This helps. I'm beginning to get the picture. I need to bone up on the equipment that goes before the amps now. Any suggestions?

Tom

My suggestion is to read all the older threads ( spread throughout this great site ) about the 4345 ( & bookmark them all / if you haven't already ).
- They do offer a very good road-map in moving forward ( quality > listening wise, IMO ).

The standard crossovers ( mentioned in those threads ) are all quite acceptable electrically ( from this guys perspective ).
- The analogue types mentioned, were models from Bryston & Ashly ( & to a much lesser extent , the ancient JBL 5235 variants ).



PS; If you decide to put a separate amp on the UHF, I believe GT was talking about a tiny classD GainClone of sorts ( preceded by its own dedicated HiPass ). This could easily be something from miniDSP ( out of China ).

[BMWCCA]

PS; If you decide to put a separate amp on the UHF, I believe GT was talking about a tiny classD GainClone of sorts ( preceded by its own dedicated HiPass ). This could easily be something from miniDSP ( out of China ).

I'd considered doing this on the 4345, some day. I don't find any inadequacies in the current setup using the bi-amp version of the crossover design here, but figured it's a simple mod easily undone, after satisfying my curiosity. I've set aside a couple of Crown D45s for this purpose, figuring to also bi-amp the 030 system one-day—just for fun—with a pair of Crown VFX-2A crossover I've had sitting around for years. Just never enough time for all the plans.

[hpham]

Hello,
After few month I had collected all drivers for 4 way: 2235H - 2121H - LE85+H91(Blue) - 077. May I follow below schematic or need to modify something for 2121H and LE85. I think 077 can take 2405 cross of 4344 is fine. I will built cabinet 4344 because we have very detail drawing in this forum.

[Ian Mackenzie]

OK I've been studying the old posts http://www.audioheritage.org/vbullet...upgrade/page14 and http://www.audioheritage.org/vbullet...-modifications for several days now. These are excruciating detailed and drawn out communications over a long period of time back in 2005 between mainly a French guy in Canada (BandKMan) and others mostly (Ian Mackenzie) and others about crossovers for 434x systems with 4313B. I am enlightened and much more informed after reading these strings. I also think I now better understand 4313B's reaction to my post last year questioning Charge Coupled Crossover Networks. Sorry I stumbled into this about 10 or more years after the fact! But I am not a troll. I was and still am an innocent and honest bystander at the wrong place at the wrong time when I questioned Charge-coupled crossovers.

It seems obvious to me from reading all this is that the way to go on a 4345 DIY crossover is the bi-amp option. My problem is I'm from the old school of what electronics were back in the 1960's. I studied and was well versed with all the Capacitor/Inductor stuff back then, but my career path led me in an entirely different direction (Air Traffic Control and Law Enforcement). Other than the Nelson Pass crossovers I built for my L300s last year, I haven't fooled with this stuff since the late 1960s. I'm still into the Amp, pre-amp and passive crossover mode. So I'm a little shaky on the bi-amping.

I am confident I can build Cross-coupled crossovers for my 4345 project with minimal advice. My question at this point is, if I go bi-amp or even tri-amp as Greg Timbers recommends for the 2405, do I just follow the schematic eliminating the LF and UHF legs of the schematic? My instinct tells me there is more to it.

It's a learning curve and early on we were still discovering historically how these filters worked.

This was the equivalent 3145 schematic charge coupled

The differences are in the mid and uhf filters compared to the stock schematic and the original filter that GT designed.

The voltage drives in all cases are almost identical.

The most recent charge coupled filter used a diode to create the screen voltage from the signal instead of the battery.

Try and use the closest dcr values for the coils.

The filters should be separated by "air" and not in close proximity to each other or any ferris metal.

As mentioned just do biamp and feed the mid filter without the series capacitor and shunt inductor.

Be careful wiring up the crossover to observe the polarity of the drivers.

The factory crossover had a number of compromises and eliminating the biamp switch improved it a lot.

The adjustment of the Lpads requires care and l have covered this in a post elsewhere

These systems has a live character and I f you can get your hands on some of the acquaplas, dusted diaphragms are an improvement.

Links to most of these points can be found in the 4345 reference thread.