| macka |
Here is the beginnings of my version of the High Low Pass crossover.
This is a two way design based on the earlier work of Grey and Moamps.
My plan is to build up the unit as a two way for my JBL monitors and use this as the learning curve for a more complex 4 way crossover for design and evaluation of drivers and systems at a latter stage.
Okay, its going to be completely adjustable, slope, crossover frequencies are fully variable and can be overlaped, and variable Filter Q so the exact crossover function can be dialed in for my existing speaker system. I decided to use the discrete class A opamps (by MOAMPS) rather than IC's and has provision for active unbalanced/balanced inputs and outputs.
At this stage acquired nearly all the parts and just got delivery of the Dale 1/4 watt resistors from Allied Electronics.
After a bit of trial and error etching the filter and opamp PCB's I realised the beauty of having the whole circuit on one large PCB. The layout was created the old way by cutting and pasting the printed art work onto clear laser transparency and gluing carefully in place. I used the Kinsten postive resist PCB material.
The board is about A4 size and had to be exposed in two sections for 10 minutes with a 40 watt Flouro tube. I then used roller tray to develop and etch the PCB as my usual trays just were'nt big enough.
Thanks to Moamps, Nelson and Karen for their support.
macka |
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| macka |
Here a wider angle of the PCB.
The white dots are where I manually marked the positions of the output coupling capacitors.
When I laid up the transparency film, the shortest signal path meant the buffers to located immediately after the filter stages. Its unremarkable that the layout in some respects will be similar to the Passlabs crossover
macka |
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| macka |
Here, some of the parts.
The capacitors are Panasonic Audio, Silmic and Panasonic FC from wkchenghk2000. His service was excellent.
The resisters are Dale R55 from Allied Electronics for all signal path elements, the other precision values will be Phillips
I am still undecided about the DC blocking capacitors. Due to shortage of PCB space I may use BlackGate N Series in E configuration. I have some large 0.01 uf polystyrene caps for the filters.
I am also unsure what to use for the 10K level. I may even use some Electro switches for that.
Any thoughts or ideas most welcome.
macka |
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| macka |
Here the case.
The 19 inch case is fabricated from 3mm sheet aluminium.
The sides, front/ back, top and bottom are held together by (4) 1 inch square solid bar sections that were turned down in the lathe as a precison matched set. Stainless steel M4 Allen key bolts are used exclusively.
macka |
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| macka |
The power supply is based on a zenor referenced regulator with Fet pass elements similar the the Bosoz and Ono regulator.
It will be located in a seperate mini case.
I figured that with the relatively low but steady current draw of the class A opamps the modest output impedance of the regulator should not be too much of an issue.
The ripple from the pre CRCRC filter is only 181 u at 180 milliamps using the Duncan simulator.
The board has large earth track encircling the active stages. I actually did this to save on etching copper and figured later it would help with signal earthing both channels.
I plan to run seperate dirty supply earths wires to each filter and opamp back to a star ground point along with individual +- supply wires to each rather than daisy chain the supply wiring. There will be local supply decoupling but if I can get away with out it I will (not for pro use)
macka |
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| stefanobilliani |
Hello Macka,
Very good stuff!
I just can't avoid myself to ask where you purchase all the 2sk .
Thanks |
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| macka |
Here the speaker system with current mid/hf and uhf passive crossover and in room response measurement, a diy version of a large 4 way JBL 4345. The biamplification crossover is at 290 hertz with a 3rd order slope.
The network attenuates the mid cone driver about 5 db, the horn about 12 db and UHF driver about 10 db. So there is considerable wastage of class A watts with the X Aleph currently used to drive the system in full passive mode.Eventually I will run it fully active.
macka |
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| macka |
| quote: | Originally posted by stefanobilliani
Hello Macka,
Very good stuff!
I just can't avoid myself to ask where you purchase all the 2sk .
Thanks |
I didn't as it turns out, I asked a special diy friend in the trade and they arrived in the mail without paperwork despite my insistence.
Must have just slipped through and best left a secret.
macka |
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| moe29 |
Wow Macka!
Can't wait to see the finished product.
Isn't it cool when your PCB's turn out nice like that? Not that i've
made anything that complicated!
good luck and keep us informed. |
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| moamps |
Go Ian go:xfingers:
Good to hear from you again.
Regards,
Milan |
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| macka |
Its going to be fun and keep our friends at Passlabs on their toes.
Today I am making some nice big knobs on a lathe from 50mm aluminium (Alumina ~ American translation) machine grade alloy(2011) rod.
macka
ps Milan, Did I send you the Passlabs group photo? |
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| moamps |
You mean the one with you and Nelson hanging out with some hot chicks at what looks like Hugh Hefner's grotto? I got that one.:D
Regards,
Milan |
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| macka |
Na,
The one at Nelson's kitchen table......I was on my best behaviour.
Oddly we never quite got around to discussing the in's and outs of the XVR1....
Ian:cool: |
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| promitheus |
How is it going ?
Really would like to see some pictures.
I want to make something like that soon. |
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| macka |
| quote: | Originally posted by promitheus
How is it going ?
Really would like to see some pictures.
I want to make something like that soon. |
Yeah, Yeah .....
You need to be more specific? Nelson's kitchen table?
I cropped mine out for this image, drilling a pcb on her indoors table could be dangerous.
There's lots of holes in this board, so much so I went and bought a new camera to prove it.
I've done the daughter boards and about half way on the mother board. Can't wait to fire it up. Building a new X Aleph 75+75 for the bi amp show.
macka |
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| GeorgeBoles |
Hello Macka,
Yes I know I said I was going to head off to the beach for a swim BUT ....
Have you got a schematic for your nice looking PCB. Finished the project yet? How does it sound.
Regards,
George! |
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| macka |
Do a search for the Moamps crossover.
The thread is in the solid state forum..its all there.
The project will take a little while to complete...I never set dedlines for myself.
macka |
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| macka |
Here I digress slightly.
A short excursion to my fathers garage for some how to skills on making some knobs. I should have one finished tomorrow.
Its actually not that simple and we created quite a detailed drawing before commencing the cutting. The diameter will be 48 mm finished and 25mm deep, the rear recess is 20mm x 4 mm deep.
I plan to use these with the Electro switches (kindly sent to me by Nelson) on the BOSOZ and a slightly smaller version on the High Low Pass.
macka:cool: |
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| macka |
Here the almost finished aluminium knob on the switch.
Much easier to turn with the large diameter.
If we make some more we will probably use a brass bushing with the stanardised 1/4 inch shaft.
macka:cool: |
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| macka |
A bit of progress here,
Had to order the Dales from Allied, freight was a killer but no choice.
I am a bit miffed by R28/R29 (10K), can't find it on the filter layout.
(R10/1 appears to be the same part but 4.7K)
Perhaps Moamps can enlighten me.
Ian |
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| macka |
Here's the new knobs on the BOSOZ, well worth the effort.
Ian |
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| Taco |
| Very good looking nobs! How long did it take you to make one? |
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| macka |
Too Long but it was fun.
I used 50mm machine grade aluminium and spun down to 48 mill, then milled out a 16 mill x 4 mill rear section, then the 1/4 inch shaft hole and then grub screw.
Next time I will make a brass sleeve insert.
Here is the Lathe. Its not a large machine but it is capable of precision.
Ian |
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| Brian Donaldson |
For those of you without a lathe, (like myself) Here's what I was able to do with a chop saw and drill press.
Cut to lenght, drill 1/4" hole as close to center as possible, deform the end of a piece od 1/4" rod and drive it into the hole, Chuck in a drillpress set to highest speed and work it with a file, then sand paper. Also, no hole for set screw.
I made 2 for my APOX preamp I'm working on
Not to say I don't wish I had a lathe though. I need a 12000 sf shop with all the equipment I could fit inside, but can't justify it.
Oh yea ... Nice work..,. and I'm eagerly awaiting your results on the crossover. I plan to have one inside my preamp. |
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| Taco |
Wow, good thinking Brian :).
I'll try this method the next time I need some knobs, because I have not a lathe either. |
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| Nelson Pass |
Well, Ian, now I'm sorry I didn't put you to work while you
were here. :cool: |
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| macka |
Well I was there on official business if you call that giving the Diva a big hug!. But I would not call that work.
Ian
:cool: |
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| macka |
It's coming along.
Next weekend I'll mount the headers and remainng passives.
Ian:cool: |
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| Taco |
| Wow, very neat looking pcb you've got there :cool:. |
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| macka |
Thanks,
The proof will be in eating the peanut butter and chocolate.
Ian :yummy: |
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| macka |
Here the top size of the main Pcb almost complete..I ran out of headers.
All going well the board should be ready for testing by weeks end.
Ian |
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| macka |
This picture shows the pbc now almost complete in the box.
macka |
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| george a |
Nice work Macka
Where did you pick up the 2sk389 and how much?
Cheers |
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| macka |
They were a gift from a special friend, now departed.
maCKA |
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| george a |
Macka
Sad to hear of your departed special friend,
no doubt memories will return each time you play music |
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| jacco vermeulen |
| quote: | Originally posted by macka
Too Long but it was fun. Next time I will make a brass sleeve insert. |
How about Chromed brass next time, just an idea.
This 1 of a set of 4, two of 50 mm and two of 30 mm.
Made from round solid brass hollowed for weight to a wall thickness of 5 mm, with a machined base, welded together.
Polished, engraved and then chromed. |
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| jacco vermeulen |
| machining the baseplate is nice, you can glue a teflon ring in it. |
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| jacco vermeulen |
| quote: | Originally posted by Brian Donaldson
Cut to lenght, drill 1/4" hole as close to center as possible, deform the end of a piece od 1/4" rod and drive it into the hole |
Drill a hole a couple of mil smaller, put the rod in the frigg, the nob in the oven and you can shrink the nob on the rod. |
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| macka |
I just fired up the active crossover.
First impressions:
WOW.
I have to go out now, been working on this job all day for a glimps of what it might do.
I think this is unit is going to be very very good.
Playing Eva Cassidy there is a sense of absolutely transparent, utterly natural vocals and purity.
You just can't hear the electronics at all. This has always been a problem with prior art active crossovers imho.
Here's a picture of the rig in a state of flux. To the left some of the class A Aleph mono blocks, the 4345 monitor, atop it the Passlabs Bride of Son of Zen and to the left of it the High Low Pass active crossover out of the box just in case of the need for the technicians touch. Also at the moment its running on a standard chip regulator for test purposes.
More news later in the week.
Ian |
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| george a |
Hi Macka
Any chance of having a gander at the artwork for your pcb layout?
...please??
Thanks
PS I am in two minds - this gizmo you've built or the DCX2406 by behringer... |
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| macka |
The layout was largely a cut and past effort with an art knife.
PS I am in two minds - this gizmo you've built or the DCX2406 by behringer...
Not appropriate for AAA hifi.
Ian |
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| george a |
Thanks Macka
My concern is that the DCX2496 might not be that great -due to varying reports.
on the otherhand I have no doubt that whats you've built is pretty good indeed, albeit a lot of time and work but not as versatile.......
The dcx in can get in a few days and I suspect probably not much different in cost...
what to do what to do..... |
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| macka |
True,
Try hiring one out, then buy.
If you want really quaility in digital look at DEQX. About $3K
Ian |
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| macka2 |
Finally got this project going and will post pics soon.
Very impressive subjective performance.
Many thanks to Moamps and other forum members for sharing their knowledge and ideas.
Macka |
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| Nelson Pass |
| quote: | Originally posted by macka
The layout was largely a cut and past effort with an art knife.
PS I am in two minds - this gizmo you've built or the DCX2406 by behringer...
Not appropriate for AAA hifi. |
I'm inclined to agree, but once you've used something like the
Behringer to home in on a curve, you can duplicate it with a
less adjustable but higher quality circuit. |
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| Variac |
I recently have found the Behringer for $250 online.. amazing really
Thats a lot of entertainment for your dollar! |
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| macka |
Well at least this design kills the myth that active crossovers suck.
I just can't hear it in the signal path using Aleph 60's.
All credit goes to Nelson for the inspiration.
Those XRV1 Pcbs at the facory looked beautiful...but there were other more beautiful attractions to admire at the time....K.
Ian;) |
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| macka |
There a nice Blue Led on the front panel.
Also special thanks to Milan
Ian |
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| macka |
And the interior..the fun part.
Ian |
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