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Post by Deleted on Jul 13, 2012 1:29:17 GMT
I used to have an article where quantities of BC109C (metal can) were purchased and the very highest HFE samples were used in different configurations, including emitter follower. The results were substantially better than that.Selected very high gain BC549C should also be quite suitable. Alex
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XTRProf
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Post by XTRProf on Jul 13, 2012 4:25:40 GMT
Frans, circuit, circuit drawing, please. We are just lowly "cathode" followers and not "SOTA" drivers like you. There is hope now!
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Post by Deleted on Jul 13, 2012 6:04:44 GMT
You certainly have a point there. The speakers I use in DIY designs don't need passive equalizing (selected this way) so passive filtering can easily be swapped. Even some passive 'correction' networks can be implemented (see my ortho headphone) and tailored even better than with passive networks which have limitations.
In Chris's case there seem to be no equalizing networks so should give no problems. he would be going from a 3rd order to a 4th order filter and this in itself can be beneficial or not. If I were him I would still include a 22uF cap in series with the tweeter though for protection.
The regular DIY'er might indeed have a difficult time replacing certain passive filters and get the best sound (not necesarily what the manufacturer intended) also active filtering gives a very good opportunity to experiment and adapt to the room acoustics/personal taste as well.
When implemented correctly (experience and gear needed) the active XO will certainly beat the passive one in all corners.
With emitter followers (without any substantial load) and when measured at only say 1kHz you might get indeed a distortion figure into the 0.001% region but not a THD figure that low unless you pull the bag of tricks which isn't possible here.
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Post by Deleted on Jul 13, 2012 6:07:37 GMT
Frans, circuit, circuit drawing, please. We are just lowly "cathode" followers and not "SOTA" drivers like you. There is hope now! Only when someone has actually bought the PCB and is building it I will give the pointers on how-to. It doesn't make sense to put time in it when it is not built anyway.
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XTRProf
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Post by XTRProf on Jul 13, 2012 6:32:22 GMT
Frans, circuit, circuit drawing, please. We are just lowly "cathode" followers and not "SOTA" drivers like you. There is hope now! Only when someone has actually bought the PCB and is building it I will give the pointers on how-to. It doesn't make sense to put time in it when it is not built anyway. Frans, you are right. Don't waste your time when nobody is building one. Chris and Alan, you first or me? I'm too burning the midnight oil on OCD network stuffs now. Btw, I will go for the 3 way, fyi.
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pagan
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Post by pagan on Jul 13, 2012 7:41:06 GMT
I dug out an old crossover I had in the garage. Used to use it for searching for the best crossover point in speakers many many years ago. Havn't used it in a long time. Marchant XM16 crossovers capable of 48db per octave www.marchandelec.com/xm16.htmlPS all I did was purchase the crossover pcb's Uploaded with ImageShack.usUploaded with ImageShack.usRecently I did get some LME79810's for it and was going to JLH them too. But in the back of my mind, it's still opamp based. aaaahhh! My Technical (logical) side say's why not, my other side say's No Hmmmm my head hurts
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Post by Deleted on Jul 13, 2012 9:34:49 GMT
Well thanks Allan your posted pics have settled my mind on just giving whatever (XO wise) is inside my ( thirty plus) speaker boxes a spring clean. The music up here in the den sounds great to my ears, and really, that's what counts. Sorry Chris and Chong if that don't push the envelope, best of luck in your quest. Alan
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Post by pagan on Jul 13, 2012 12:37:17 GMT
Yes Alan I think they maybe a bit excessive But that is a 3 way crossover, 48db on 2 and 24db on the other 2. I was thinking about JLH'ing the psu's but we'll see.
First thing you should do for your speakers is check what caps are used. Electrolytic caps dry out over time.
Allan
Do have to agree with solderdude One thing with electronic crossovers is it's still wise to put a cap before the tweeter
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Post by XTRProf on Jul 13, 2012 13:18:29 GMT
Sorry Chris and Chong if that don't push the envelope, best of luck in your quest. Well, that leaves the 2 of us. So let's go to OK Corrall to draw on this Friday 13. On a serious note, I think you better draw first as I'm too preoccupied with networking now. Not job but computers though.
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Post by XTRProf on Jul 13, 2012 13:20:56 GMT
Alan,
Wow, your XO really looks mean and complex with lots of Op Amps.
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Post by Deleted on Jul 17, 2012 22:34:30 GMT
Only when someone has actually bought the PCB and is building it I will give the pointers on how-to. It doesn't make sense to put time in it when it is not built anyway. I've ordered one up! If all goes to plan I should have all the normal components for the build by the time it arrives in approxiamately 2 weeks. Frans, Any pointers and help will be very gratefully received
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Post by XTRProf on Jul 17, 2012 23:14:59 GMT
I've ordered one up! If all goes to plan I should have all the normal components for the build by the time it arrives in approxiamately 2 weeks. Good, you be the first guinea pig and I look from the sideline as reserve.
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Post by Deleted on Jul 17, 2012 23:40:45 GMT
Hehehe Attachments:
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Post by Deleted on Jul 18, 2012 4:22:01 GMT
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Post by XTRProf on Jul 18, 2012 5:32:27 GMT
Actually doesn't matter anymore as long as which sounds better. Usually the XO up stream will sound better.
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Post by Deleted on Jul 18, 2012 12:24:35 GMT
Everyone is entitled to their own opinions regarding filters. Let your own ears be the deciding factor. For the ESP PCB modders: www.mediafire.com/view/?yga5uw46vtjoy1dHere are some proposals for opamp replacement. They can only be used for this particular circuit and not as an opamp replacement. Note that the output of the circuit needs AC coupling now so an output cap MUST be fitted. I recommend you fit good quality opamp sockets and build up one of the circuits on another socket so you can easily replace the circuit with an opamp. Opamps will always give better results than the proposed circuits even when cheap opamps are used !
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Post by Deleted on Jul 18, 2012 21:55:08 GMT
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Post by XTRProf on Jul 19, 2012 1:45:12 GMT
But that's not a Linkwitz-Riley Electronic Crossover. Also, it's still op amp based and no 3 ways.
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Post by Deleted on Jul 19, 2012 2:29:59 GMT
But that's not a Linkwitz-Riley Electronic Crossover. Also, it's still op amp based and no 3 ways. I did say it was a simple option. Anyway, most hobbyists can't even get 2 way electronic crossovers right with their particular speakers, let alone 3 ways !!! Besides, the title of this thread is Re: Active crossover; 2 way
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pagan
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Post by pagan on Jul 19, 2012 8:37:28 GMT
But that's not a Linkwitz-Riley Electronic Crossover. Also, it's still op amp based and no 3 ways. I thought it was a LR, IIRC, but I'm not looking too closely. single pcb, one channel, 2 outputs Low and High. For three way add another pcb per channel.
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Post by XTRProf on Jul 19, 2012 9:55:10 GMT
I thought it was a LR, IIRC, but I'm not looking too closely. single pcb, one channel, 2 outputs Low and High. For three way add another pcb per channel. Oh, is it? Then modifying this will be better as then it's pure mono. Suddenly this seems better. Frans, if not too much to ask on mode?
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Post by Deleted on Jul 19, 2012 12:39:46 GMT
see reply #40
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Post by Deleted on Jul 19, 2012 12:56:26 GMT
But that's not a Linkwitz-Riley Electronic Crossover. Also, it's still op amp based and no 3 ways. I may have this confused with another design but I think it's this one, from my reading aound on these, that can be configured for either LR or Bessell. Additionally, after looking at Frans' Mediafile link (thank you), I researched a liitle further and found more designs specifically for use on the ESP board. They are out there Chong. There is also the thought of the GD Audio Earth/Moon/Sun modules but I think they'd be too power hungry after having problems with them before. For starters I'll stick to the opamps, especially as the rest of system uses them anyway. (My previous active system was ALL discrete).
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Post by XTRProf on Jul 19, 2012 14:44:51 GMT
So it's LR after all and exactly the same as Elliot's LR PCB?
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Post by XTRProf on Jul 19, 2012 14:54:21 GMT
I may have this confused with another design but I think it's this one, from my reading aound on these, that can be configured for either LR or Bessell. Additionally, after looking at Frans' Mediafile link (thank you), I researched a liitle further and found more designs specifically for use on the ESP board. They are out there Chong. So which one can be for both? The Altronic or ESP PCBs? Anyway, who wants Bessel? There is also the thought of the GD Audio Earth/Moon/Sun modules but I think they'd be too power hungry after having problems with them before. Wow, that will be a costly path. For starters I'll stick to the opamps, especially as the rest of system uses them anyway. (My previous active system was ALL discrete). I will still go the discrete path with DIP8 so that I still can change to op amp if not too good a result. But which PCB to buy? Until I can get some confirmation from what I have written, I will prefer the pure mono Altronic version if all adds up. Alex, is there just the Altronic PCB without parts version as the components are not too great in that Altronic kit?
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