Hi all,
I plan to clone JBL DD6700 with my drivers as follows: Altec 515b, Altec 416a, JBL 375 and super tweeter Jbl 077.
But seeing the schematic of the mid, i dont understand at all.
Could anyone explain to me the way it works? The diodes, C1, C2, C3, L7, C14, C15, R12 what they are about? Many thanks.
I plan to clone JBL DD6700 with my drivers as follows: Altec 515b, Altec 416a, JBL 375 and super tweeter Jbl 077.
But seeing the schematic of the mid, i dont understand at all.
Could anyone explain to me the way it works? The diodes, C1, C2, C3, L7, C14, C15, R12 what they are about? Many thanks.
The idea is that music (ac) will get rectified by the diodes, low current wise, and generate a dc voltage across the capacitors. Hence the capacitors in series, otherwise it wouldn't work.
This way, the capacitors will exhibit tension on the foils and generate less distortion.
In theory. I never saw a paper that proves the theory, but being JBL, it might just be "out there";-)
This way, the capacitors will exhibit tension on the foils and generate less distortion.
In theory. I never saw a paper that proves the theory, but being JBL, it might just be "out there";-)
As an alternative you could replace those circuits with a single capacitor of half the capacitance value. The schematic has such a low resolution that I can't make out what cap is C1, C2 etc. Otherwise I would have made an example.
Ehm,...there's nothing that needs to be replaced BECAUSE 1) those LCR nets are notches that are tuned to the particular speaker that they are attached to 2) those diodes all go to point A which is attached to the positive of a 9 V battery
Just in case, you can traslate this article https://www.audioreview.it/prove/storiche/jbl-everest-dd66000.html
Just in case, you can traslate this article https://www.audioreview.it/prove/storiche/jbl-everest-dd66000.html
Allright, time for a bit more in depth answer:
E.g. capacitors C12 and C13 are in series, the induction directly above them, as well as the resistor below them, act in tandem to lower the impedance at a certain frequency, with a specific bandwith. In short: together with the previous filter components before, as well as being parallel to the driver further up, it will suck energy out of the system. These type of circuits are mostly used to lower resonances, but might also be used to attenuate a bit more wide regarding bandwidth
Someone here would probably be very happy simulating that stuff, I'll let that be if you don't mind.
The two capacitors are in series. Normally,outside of JBL, two are hardly used in cross over loudspeaker filters, because 1 will suffice.
JBL has used batteries (indeed 9 volts), but iirc also the type where a high resistance driven rectification was found to give the same results, and without needing to change the batteries every 10 years or so.
It doesn't really matter. If you don't want to use that theory, leave 1 capacitor out and half the value of the other one. Also: get rid of the diode and the resistor.
In this case, there's 4 caps. So you could use 2: 75 uF and 3 uF in parallel means a total of 78uF. Effective capacitance is 78/2=39uF. That's the value you have to get, if you would use the same drivers.
Now, it's just that you won't use the same drivers, am I right? In that case these values could be completely off, because they do depend on the original drivers, their single and sum output, their own resonances etc.
Iow. You might want to imitate this filter, but no guarantees it will sound good.
I sincerely hope you can find someone who has built the speaker you plan on building and ask what he has done.
Anybody here?
E.g. capacitors C12 and C13 are in series, the induction directly above them, as well as the resistor below them, act in tandem to lower the impedance at a certain frequency, with a specific bandwith. In short: together with the previous filter components before, as well as being parallel to the driver further up, it will suck energy out of the system. These type of circuits are mostly used to lower resonances, but might also be used to attenuate a bit more wide regarding bandwidth
Someone here would probably be very happy simulating that stuff, I'll let that be if you don't mind.
The two capacitors are in series. Normally,outside of JBL, two are hardly used in cross over loudspeaker filters, because 1 will suffice.
JBL has used batteries (indeed 9 volts), but iirc also the type where a high resistance driven rectification was found to give the same results, and without needing to change the batteries every 10 years or so.
It doesn't really matter. If you don't want to use that theory, leave 1 capacitor out and half the value of the other one. Also: get rid of the diode and the resistor.
In this case, there's 4 caps. So you could use 2: 75 uF and 3 uF in parallel means a total of 78uF. Effective capacitance is 78/2=39uF. That's the value you have to get, if you would use the same drivers.
Now, it's just that you won't use the same drivers, am I right? In that case these values could be completely off, because they do depend on the original drivers, their single and sum output, their own resonances etc.
Iow. You might want to imitate this filter, but no guarantees it will sound good.
I sincerely hope you can find someone who has built the speaker you plan on building and ask what he has done.
Anybody here?
Thank you so much for your explanation. from what you just explained, this kind of diode and 2 caps in series are just the JBL way to make the caps the least distortion, even though there's no prove about it. And we can replace those parts by 1 single capacitor with half the value of 1 of them. OK, let's just asume they are just 1 single cap, I would like to describe the way the signal goes like this: The signal from the amp (?) goes to the YEL/BLK one, they will pass 3 continous RLC circuits (which are impedance matching: C789, R9,10,11, and L4,5,6), and crossing RLC (R12, C14,15, L7), this circuit is mid band filter in 1st order and attenuated by R12 and the signal simultanately passés RL circuits (R7,8 in parallel and in series with L3), this circuit i dont know what it is for. After the 1st order filter, it goes to the C1,C2,C3 notch which i assume C1,C2 is corresponding to a single cap as you explained. But i dont know why they have 5 outputs with a switch and the functions of C3, L1, L2. Pls help.
exactly, just that the absolute attenuation is R1----R6, on R7&R8, R12 works both as a way to higher the impedance seen by crossover C14&C15 (and L7 of course), which works to lower the crossover frequency, otherwise 1uF would be way to high value. It also helps in getting the amplitude (volume as you will) rise with higher frequencies, to adjust for directivity of the horn.
In other words, you`d have to simulate to know whats really going on, it`s a real intricate circuit and only suited to the driver it connects to. You seem to et the idea of the filter, if you are getting along with doing measurements you could try to fit your driver and tweak it. Could be touch though..
I have listened 2 long nights to this system, driven actively ( Jadis and McIntosh connected) and with a 21 inch corrected active sub. It`s amazing, best mid driver I have ever heard, as far as I could extract that detail out of the whole system: never any fatigue or honkiness, totally free from any colouration without getting dull, "too much detail", mids detached from mid bass or low frequencies, or anything else in the way.
In other words, you`d have to simulate to know whats really going on, it`s a real intricate circuit and only suited to the driver it connects to. You seem to et the idea of the filter, if you are getting along with doing measurements you could try to fit your driver and tweak it. Could be touch though..
I have listened 2 long nights to this system, driven actively ( Jadis and McIntosh connected) and with a 21 inch corrected active sub. It`s amazing, best mid driver I have ever heard, as far as I could extract that detail out of the whole system: never any fatigue or honkiness, totally free from any colouration without getting dull, "too much detail", mids detached from mid bass or low frequencies, or anything else in the way.
Thanks alot for your support and the documents. I find it's hard to follow this schematic. GUess i'll do it my way, the simple one.
No I wasn't. If you read the article I linked, you just have to see the photo in which there are the batteries.
It's known that JBL likes to 'polarize a little' the caps in the crossover, so here's the explanation of where those diodes go, in that schematic.
About the second sentence, in your extended reply argumenting the why's and how's of that crossover & other complex engineering regarding speaker design, you say exactly that those nets are for just that particular driver.
"
Ehm,...there's nothing that needs to be replaced BECAUSE 1) those LCR nets are notches that are tuned to the particular speaker that they are attached to 2) those diodes all go to point A which is attached to the positive of a 9 V battery
Just in case, you can traslate this article https://www.audioreview.it/prove/storiche/jbl-everest-dd66000.html
I read the article.
I never said it has to be replaced, it can be replaced if OP needed that, for simplification and that was what the explanation was for.
In your reply the diode is wrongly connected to polarize the caps, in your explanation it charges not the net but music would charge the battery, but only with 9 volts ( 18 volts + Udiode Peak to Peak * 2, roughly calculated) which would mean way more than 120 dB or so. This is surely not what you meant, so it was erratic.
To be precise: it would need to be connected to the negative pole or the battery.
Ehm,...there's nothing that needs to be replaced BECAUSE 1) those LCR nets are notches that are tuned to the particular speaker that they are attached to 2) those diodes all go to point A which is attached to the positive of a 9 V battery
Just in case, you can traslate this article https://www.audioreview.it/prove/storiche/jbl-everest-dd66000.html
I read the article.
I never said it has to be replaced, it can be replaced if OP needed that, for simplification and that was what the explanation was for.
In your reply the diode is wrongly connected to polarize the caps, in your explanation it charges not the net but music would charge the battery, but only with 9 volts ( 18 volts + Udiode Peak to Peak * 2, roughly calculated) which would mean way more than 120 dB or so. This is surely not what you meant, so it was erratic.
To be precise: it would need to be connected to the negative pole or the battery.
That`s oke theanhngn, I hope you`ll get on your way.
You can always draw some lessons from this schematic and try to incorporate it in your own, to see what it does.
You sure has a talent in reading schematics, so just try and find out -)