MOX - active crossover

moamps · 2004-02-17 2:17 pm

hacknet said:
would this also mean i can omit the "offset" part of the circuit?

Hi,

If you dont need offset in upper decade you can omit 100pF cap.
This offset gives to you double precision (or resolution) in seting xover frequency (covering whole audio band with 60 break frequency).

Regards

hacknet · 2004-02-17 4:00 pm

okay thanks! i don`t think i`ll be omiting the the offset part of the story

Raka · 2004-02-27 7:48 am

I can't believe, we all were waiting for an active xover, like mana, appears this great thing and the thread dies as soon as the rain drops fall.
I'm going to build it, and have some questions:
- Besides the cost, there is no problem using a selector and some relays to do the selection of slopes, etc, from the front pannel, is it?
- My only doubt is to use discrete or IC opamps. If I use the relays solution maybe there is not too much space in a standard rack, maybe I use a two boards solution. Has anyone had the chance to compare both IC and discrete opamps?
By the way, I still don't understand very well this offset thing, any help?

Andypairo · 2004-02-27 7:59 am

Raka said:
I can't believe, we all were waiting for an active xover, like mana, appears this great thing and the thread dies as soon as the rain drops fall.
I'm going to build it, and have some questions:
- Besides the cost, there is no problem using a selector and some relays to do the selection of slopes, etc, from the front pannel, is it?
- My only doubt is to use discrete or IC opamps. If I use the relays solution maybe there is not too much space in a standard rack, maybe I use a two boards solution. Has anyone had the chance to compare both IC and discrete opamps?
By the way, I still don't understand very well this offset thing, any help?

I guess that many of us are still waiting for Godot (aka Pass DIY Xover

), and since this is a daring project there's a little fear to take the wrong route.
If Nelson wasn't planning to release his own project we would probably be involved in a group buy for this x-over (or for Uli's one)....

PS I'm starting gathering parts for this project (i.e. 2SK389BL from Schuro with the group buy)

Apart from that :xeye:

using relays complicates somewhat the layout, and since a active xover is something to set once for all (after some experimenting of course) I wouldn't bother adding this complexity.
Of course if you like changing slopes/frequencies on the fly... just do it.

For the opamps is relatively easy to make a small PCB to fit a DIL (or even a SMD) opamp on the SIL connector proposed, so you can easily compare.

Cheers

Andrea

Raka · 2004-02-27 8:34 am

Andypairo said:
I guess that many of us are still waiting for Godot (aka Pass DIY Xover ), and since this is a daring project there's a little fear to take the wrong route.

We are becoming a bit lazy lately, wanting the sign of the Master :clown:

I'm thinking about the xover as a tool, so maybe the relays are better option. I'm building now a preamp based on an IC opamp, so I'll leave space for upgrading with a discrete one and check the differences. I'll report, of course

BTW, what group buy for Shuro??? Have I missed something?

Andypairo · 2004-02-27 9:39 am

BTW, what group buy for Shuro??? Have I missed something?

Check in the Trading Post section, but don't worry, you're still in time.

Cheers

Andrea

Fred Dieckmann · 2004-02-27 10:50 am

Lets not forget who ironed out some the details on how to do this

"I guess that many of us are still waiting for Godot "

I'm waiting for Gray......... much the same thing.

A great play by the way.

Raka · 2004-02-27 10:55 am

Re: Lets not forget who ironed out some the details on how to do this

Fred Dieckmann said:
A great play by the way.

Fred, English is not my mother language, could you please explain me what do you mean with that (play)? Thank you very much.

UrSv · 2004-02-27 10:56 am

Great play..

Post #44:

"I guess that many of us are still waiting for Godot" referring to the play "Waiting for Godot".

http://www.gradesaver.com/ClassicNotes/Titles/WaitingForGodot/About_the_Play.html

Raka · 2004-02-27 10:59 am

Re: Great play..

UrSv said:
Post #44:

"I guess that many of us are still waiting for Godot" referring to the play "Waiting for Godot".

http://www.gradesaver.com/ClassicNotes/Titles/WaitingForGodot/About_the_Play.html

Oh, Thanks.

Andypairo · 2004-02-27 11:05 am

Re: Lets not forget who ironed out some the details on how to do this

Fred Dieckmann said:
"I guess that many of us are still waiting for Godot "

I'm waiting for Gray......... much the same thing.

A great play by the way.

Oh .. where is Lucky? :smash:

Fred, take the whip!

Cheers

Andrea

Fred Dieckmann · 2004-02-27 11:08 am

Vladimir, be reasonable, you haven't yet tried everything

http://samuel-beckett.net/Waiting_f...muel-beckett.net/Waiting_for_Godot_Part1.html

roddyama · 2004-02-27 11:23 am

Raka said:
I still don't understand very well this offset thing, any help?

The offset allows you to switch in a different capacitor to shift the crossovers cut-off frequency. The shift can be as high as 1/6 octave up or down depending on the size of the capacitor you select for the offset circuit.

moamps · 2004-02-27 12:27 pm

Raka said:
- Besides the cost, there is no problem using a selector and some relays to do the selection of slopes, etc, from the front pannel, is it?

Hi,
be carefull with on line resistors and capacitors switching, using some temporary outputs muting circuitry is recommended. Also, PCB will be much bigger and complex with relays on board what isn't good for overall crossover quality.

My only doubt is to use discrete or IC opamps.

In this design you can switch between IC and discrete OPAMP dougther board very easy.

Regards

PS To Rodd: Thanks for offset explanation. The frequency shift can be only down for 1/6 octave with adding caps from higher decade set.

Blitz · 2004-02-28 9:50 pm

Raka said:
We are becoming a bit lazy lately, wanting the sign of the Master

Well, the Master has given us a sign:

Nelson Pass said:
Actually, since the MOX was posted over in Solid State, and
the basic circuit is virtually identical to the XVR1, and he has
made board artwork available, I figured that the pressure
should be off, and so I back-burnered it again. It will come out,
but not until I think of something better than I had.

So, if we could organize a PCB-group-Buy of MOX, I would be certainly interested. Who else ?

Variac · 2004-02-28 10:43 pm

We want boards!!!!! Who's gonna do it? Brians kinda busy right now...

bigparsnip · 2004-02-29 12:04 am

Perhapse me again? Who would be intrested in this, and would it get many orders from the forums?

Cobra2 · 2004-02-29 12:35 am

bigparsnip said:
Perhapse me again? Who would be intrested in this, and would it get many orders from the forums?

One, or maybe two for me...

Arne K

BrianGT · 2004-02-29 12:50 am

Variac said:
We want boards!!!!! Who's gonna do it? Brians kinda busy right now...

I actually am actually working on a MOX layout, with a friend, but I won't be getting the prototype boards made for quite a while.

Can't the existing layouts be used for a group order? They seem to work, and look pretty good.

The main difference with my layout plans for this project, is to keep it all one one pcb.

--
Brian

BDP · 2004-02-29 4:41 am

It would be great if someone did some boards. I would be interested in a few and would offer to help out if needed. Maybe some discrete regulators on board also??

BDP

MOX - active crossover

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