That will almost certainly degrade the speaker's performance. DCR of the inductors, ESR of the capacitors, and the inductor Q are integral parts of getting the crossover transfer function correct.
You picked a good hobby, it's just a non-trivial problem.
You have to measure the electrical response at the driver terminals with the original crossover, then design an electronic crossover with the same transfer function, or go digital and program the transfer function.returning soon
Hello all,
I see several things to comment on in the recent posts, but briefly now:-
Thankyou for posting the photos Wes - now I don't have to damage my crossover board getting it out, and can continue listening to them whilst I am trying to get some more information elsewhere.
{I like listening via these l'speakers - their point source, and almost ideal time-coherence is wonderful !}
How did you get your boards out Wes, and without damage ?
I have no more time available to day - I'll be back tomorrow - I hope.
Hello all,
I see several things to comment on in the recent posts, but briefly now:-
Thankyou for posting the photos Wes - now I don't have to damage my crossover board getting it out, and can continue listening to them whilst I am trying to get some more information elsewhere.
{I like listening via these l'speakers - their point source, and almost ideal time-coherence is wonderful !}
How did you get your boards out Wes, and without damage ?
I have no more time available to day - I'll be back tomorrow - I hope.
Taking off the boards was quite a pain, there isnt really anything to it, except for patience and perseverance...
and a hand/wrist combo thin enough to get inside the speakers...
I didnt take pics of the inside of the speakers cause i dont want to open them for now, unless necessary... { I too like to keep them closed, assembled and playing }
the pin in the pic is practicaly identical to the kef ones.
All you have to do is press the four pins as the red arrows indicate. That in itself is quite hard tho, since the pins are placed quite close to inductors/capacitors, so u have little space to press the pins. (I am quite sure you are aware of that tho.. my "secret" are my skinny hands... )
But after a good amount of pressing, twisting, pulling, pushing and cursing, the boards should come off...
and a hand/wrist combo thin enough to get inside the speakers...
I didnt take pics of the inside of the speakers cause i dont want to open them for now, unless necessary... { I too like to keep them closed, assembled and playing
}the pin in the pic is practicaly identical to the kef ones.
All you have to do is press the four pins as the red arrows indicate. That in itself is quite hard tho, since the pins are placed quite close to inductors/capacitors, so u have little space to press the pins. (I am quite sure you are aware of that tho.. my "secret" are my skinny hands... )
But after a good amount of pressing, twisting, pulling, pushing and cursing, the boards should come off...
Attachments
Thankyou Wes for posting the photos !
Now I can see what to look for.
Even with my glasses{spectacles} on I cannot see the detail of those mounting posts clearly inside the cabinet.
I have lost my best magnifying glass - I will have to find another one or buy a new one.
********************************************************
I apologise for they delay, and for not posting any more information about modifying the crossover today.
I have been trying to get some information about the components changed for the iQ30 improved crossover, but no sucess yet.
If I cannot get that information I will try another idea,
so, everyone interested, look back here again for an update later,
but if you can think of anything else that is relevant, than do post it now.
Now I can see what to look for.
Even with my glasses{spectacles} on I cannot see the detail of those mounting posts clearly inside the cabinet.
I have lost my best magnifying glass - I will have to find another one or buy a new one.
********************************************************
I apologise for they delay, and for not posting any more information about modifying the crossover today.
I have been trying to get some information about the components changed for the iQ30 improved crossover, but no sucess yet.
If I cannot get that information I will try another idea,
so, everyone interested, look back here again for an update later,
but if you can think of anything else that is relevant, than do post it now.
Alan,
You are very welcome!
I'm eargerly looking forward to your updates! x)
Gabriel,
I would very much apreciate if you could send me the manuals of both models. Should I just leave my e-mail with you?
it is wesley6 @ gm ail . com
(without the spaces)
thank you very much for your input!
Good sunday everyone!
You are very welcome!
I'm eargerly looking forward to your updates! x)
Gabriel,
I would very much apreciate if you could send me the manuals of both models. Should I just leave my e-mail with you?
it is wesley6 @ gm ail . com
(without the spaces)
thank you very much for your input!
Good sunday everyone!
Hi
I decide to make some modification to the drivers in fact I change the tweeter with a Monacor CRB, 40 and for the woofer we change the cone material, we use paper cone from some Jamo speakers. The drivers will be black with the silver plastic wave guide.
The tweeter have silk dome with aluminum voice coil.
For the woofer we use the original voice coil and in did is from aluminum wire on kapton
Tomorrow I will test him, I keep a driver untouch.
I decide to make some modification to the drivers in fact I change the tweeter with a Monacor CRB, 40 and for the woofer we change the cone material, we use paper cone from some Jamo speakers. The drivers will be black with the silver plastic wave guide.
The tweeter have silk dome with aluminum voice coil.
For the woofer we use the original voice coil and in did is from aluminum wire on kapton
Tomorrow I will test him, I keep a driver untouch.
I tested the new driver and the driver with the new diaphragm has more bass start from 30Hz the original cone has 4.8g and start from 45Hz like in the specs and the Jamo cone has 3.2g so it is less heavy. I use the same voice coil, aluminum on kapton material. I have a friend who does this job, it is his job fixes all the day drivers.
Best regards
Best regards
surprised ! .. plus bass and crossover comments ...
Extension to a lower bass frequency from a lighter weight cone -
I am very surprised !
My guess is that even though the KEF voice-coil has been fitted to the Jamo cone, perhaps your friend has used a slightly larger amount of adhesive, and this has increased the assembled weight - after the unattached cone was weighed ...
Also, perhaps the different adhesive and way attached to the cone has caused a different Qm and perhaps a different Vas to the original, and thus a different slope to the bass rolloff when in the enclosure than what would be expected for Qm and Vas changes after a lighter weight cone.
Looking at the Impedance Plots for both iQ3 and iQ30 in the Service Manuals, the cone and the vent are operating in opposite acoustic polarity to each other in the 30Hz region, thus regardless of whatever 30Hz you can measure from the driver out of that enclosure there will be no effective 30Hz audible output with the driver in that enclosure ... but there will be 2nd and 3rd Harmonic Distortions audible when it is driven by a 30Hz signal.
Sweep a sine wave slowly down from about 100Hz and listen.
You will hear the pitch descending from 100Hz down through to the tuned frequency of the vent -{at a little above 45Hz}- then as you continue to lower the frequency of the input signal you will hear the Timbre of the sound lighten - that is, it will begin to sound higher in frequency content, and that is the onset of audible harmonic distortion.
When you have swept down to about 30 Hz the 2nd harmonic and some 3rd harmonic will be dominating any 30Hz fundamental that may be remaining.
If you continue to sweep down below 30Hz the Timbre will become more of a buzzing sound - that is when the 3rd harmonic dominates over the 2nd harmonic.
Do not sweep to below about 20Hz as that may cause damage to the driver,
because you will have the volume turned up quite high to hear anything from that small driver at these low frequencies, thus there will be a lot of cone excursion.
You may hear some rattling if there are any loose parts in the enclosures.
**********************************************************
Post something about the sound after the change of dome for the tweeter when your friend has done that.
**********************************************************
The changes to the crossover components from iQ3 to iQ30 will cause a change of the roll-off slopes of both the high-pass and the low-pass filters.
I will comment more about that when I have studied the circuit for a while,
though ideally one trys both circuits and listens - and that is eventually what I will do.
For readers who have not seen the Service Manuals:-
In the treble filter the 6uF cap in iQ3 is increased to 8.2uF for iQ30,
and the 15uF cap is decreased to 11uF,
and the .125mH inductor is decreased to .1mH.
The 16uF cap is increased to 20uF in the bass filter's Zobel,
and the 1.1mH inductor is decreased to 1mH.
The resistors in both filters are the same in both iQ3 and iQ30, and are 1.2ohm in the treble circuit, and 6.8 ohm in the bass circuit zobel.
Extension to a lower bass frequency from a lighter weight cone -
I am very surprised !
My guess is that even though the KEF voice-coil has been fitted to the Jamo cone, perhaps your friend has used a slightly larger amount of adhesive, and this has increased the assembled weight - after the unattached cone was weighed ...
Also, perhaps the different adhesive and way attached to the cone has caused a different Qm and perhaps a different Vas to the original, and thus a different slope to the bass rolloff when in the enclosure than what would be expected for Qm and Vas changes after a lighter weight cone.
Looking at the Impedance Plots for both iQ3 and iQ30 in the Service Manuals, the cone and the vent are operating in opposite acoustic polarity to each other in the 30Hz region, thus regardless of whatever 30Hz you can measure from the driver out of that enclosure there will be no effective 30Hz audible output with the driver in that enclosure ... but there will be 2nd and 3rd Harmonic Distortions audible when it is driven by a 30Hz signal.
Sweep a sine wave slowly down from about 100Hz and listen.
You will hear the pitch descending from 100Hz down through to the tuned frequency of the vent -{at a little above 45Hz}- then as you continue to lower the frequency of the input signal you will hear the Timbre of the sound lighten - that is, it will begin to sound higher in frequency content, and that is the onset of audible harmonic distortion.
When you have swept down to about 30 Hz the 2nd harmonic and some 3rd harmonic will be dominating any 30Hz fundamental that may be remaining.
If you continue to sweep down below 30Hz the Timbre will become more of a buzzing sound - that is when the 3rd harmonic dominates over the 2nd harmonic.
Do not sweep to below about 20Hz as that may cause damage to the driver,
because you will have the volume turned up quite high to hear anything from that small driver at these low frequencies, thus there will be a lot of cone excursion.
You may hear some rattling if there are any loose parts in the enclosures.
**********************************************************
Post something about the sound after the change of dome for the tweeter when your friend has done that.
**********************************************************
The changes to the crossover components from iQ3 to iQ30 will cause a change of the roll-off slopes of both the high-pass and the low-pass filters.
I will comment more about that when I have studied the circuit for a while,
though ideally one trys both circuits and listens - and that is eventually what I will do.
For readers who have not seen the Service Manuals:-
In the treble filter the 6uF cap in iQ3 is increased to 8.2uF for iQ30,
and the 15uF cap is decreased to 11uF,
and the .125mH inductor is decreased to .1mH.
The 16uF cap is increased to 20uF in the bass filter's Zobel,
and the 1.1mH inductor is decreased to 1mH.
The resistors in both filters are the same in both iQ3 and iQ30, and are 1.2ohm in the treble circuit, and 6.8 ohm in the bass circuit zobel.
Hi
After I will finish modifying the speakers I will put some photos and make comments about the sound. Hope to finish until next Sunday. I have also in mind to paint the speakers in piano black. Another project I have is a pair of 21L bookshelf with Grundig drivers.
Best regards
After I will finish modifying the speakers I will put some photos and make comments about the sound. Hope to finish until next Sunday. I have also in mind to paint the speakers in piano black. Another project I have is a pair of 21L bookshelf with Grundig drivers.
Best regards
Attachments
Hey I'm new in this speaker building "business" and I don't really know anything about it.
I just got my hands on 2 Sp 1535 and found out that they are combined with the Sp 1542 tweeter. After buying those tweeters and assembling a case I am now trying to get some information about the electronic needed.
I really appreciate your work and look forward to hear about your final solution alan!
Greets ligger
I just got my hands on 2 Sp 1535 and found out that they are combined with the Sp 1542 tweeter. After buying those tweeters and assembling a case I am now trying to get some information about the electronic needed.
I really appreciate your work and look forward to hear about your final solution alan!
Greets ligger
tweeter information ?
Hi ligger,
SP 1535 is the basic drive unit in iQ3 - at least for the bass-mid driver.
I did not know the tweeter had a different SP number, as I can see no evidence of that in my iQ3s.
Perhaps SP 1535 is the bass-mid for both iQ3 and iQ30,
because the only difference in the drivers seems to be the tangerine wave guide fixed around the tweeter dome in iQ30,
OR, perhaps the entire driver including woofer and tweeter in iQ30 is SP 1570 - I am not sure, because I have not seen inside an iQ30.
The tweeter is in the centre of the bass-mid driver.
It can be removed - carefully - by unscrewing the back, but I have NOT yet done this ... as I have not had time available to continuing modifying yet.
A separate tweeter should not have to be bought, because it should have been installed in the centre of the bass-mid driver at the factory.
Where did you find the SP 1542 information ?
Post a detailed description of SP 1542, or a photo if you can, so that I can determine further.
Hi ligger,
SP 1535 is the basic drive unit in iQ3 - at least for the bass-mid driver.
I did not know the tweeter had a different SP number, as I can see no evidence of that in my iQ3s.
Perhaps SP 1535 is the bass-mid for both iQ3 and iQ30,
because the only difference in the drivers seems to be the tangerine wave guide fixed around the tweeter dome in iQ30,
OR, perhaps the entire driver including woofer and tweeter in iQ30 is SP 1570 - I am not sure, because I have not seen inside an iQ30.
The tweeter is in the centre of the bass-mid driver.
It can be removed - carefully - by unscrewing the back, but I have NOT yet done this ... as I have not had time available to continuing modifying yet.
A separate tweeter should not have to be bought, because it should have been installed in the centre of the bass-mid driver at the factory.
Where did you find the SP 1542 information ?
Post a detailed description of SP 1542, or a photo if you can, so that I can determine further.
Last edited:
Hi
My IQ3 are in the process of rebuilding. I changed the Plastic mid woofer cone with Paper cone, and the original tweeter with another one that use silk dome. For the mid bass driver I use the same voice coif because is light, they use aluminum coil for both drivers.
I remove the metal shield from the magnets. After I will finish this project I will put some pictures. All this jobs was done by a fried of mine, it is day to day job to repair audio drivers, and he is an expert.
For crossover we will use an active crossover to determine the point where to cut, after we will make a classic crossover.
Best regards
My IQ3 are in the process of rebuilding. I changed the Plastic mid woofer cone with Paper cone, and the original tweeter with another one that use silk dome. For the mid bass driver I use the same voice coif because is light, they use aluminum coil for both drivers.
I remove the metal shield from the magnets. After I will finish this project I will put some pictures. All this jobs was done by a fried of mine, it is day to day job to repair audio drivers, and he is an expert.
For crossover we will use an active crossover to determine the point where to cut, after we will make a classic crossover.
Best regards
2 magnets ?
Hi Gabriel,
great photos !
Are there 2 magnets on the back of the KEF driver's chassis in one of your photos - or is the other dark coloured disc that looks like a magnet actually something else ?
The tweeter section of the dual-concentric driver would use the same magnet in this KEF design, unless one of the voice-coils is set back behind the other ...
what do the voice coils look like ? ...
and what does your technician friend say about this ?
I will return to our other discussion about crossovers as soon as I have sufficient time available to write that completely.
This post is a quick one so that you know I am still following !
Hi Gabriel,
great photos !
Are there 2 magnets on the back of the KEF driver's chassis in one of your photos - or is the other dark coloured disc that looks like a magnet actually something else ?
The tweeter section of the dual-concentric driver would use the same magnet in this KEF design, unless one of the voice-coils is set back behind the other ...
what do the voice coils look like ? ...
and what does your technician friend say about this ?
I will return to our other discussion about crossovers as soon as I have sufficient time available to write that completely.
This post is a quick one so that you know I am still following !
Hi
What you see is the original KEF driver except the paper cone. For the high frequency I will use a Monacor driver.
When I will finis the drivers I will describe what I change to make them better. For the moment I will use the original voice coil, original suspension, original magnets and original chassis. I will change only the paper cone and the tweeter.
What I see until now after lots of testing is that you will discover different sounds only by changing the paper con. The quality construction of the paper cone gives the sound of the speakers. Also the voice coils is very important but in our case we want to use the aluminum Kef voice coils. I will put more info soon.
What you see is the original KEF driver except the paper cone. For the high frequency I will use a Monacor driver.
When I will finis the drivers I will describe what I change to make them better. For the moment I will use the original voice coil, original suspension, original magnets and original chassis. I will change only the paper cone and the tweeter.
What I see until now after lots of testing is that you will discover different sounds only by changing the paper con. The quality construction of the paper cone gives the sound of the speakers. Also the voice coils is very important but in our case we want to use the aluminum Kef voice coils. I will put more info soon.
tweeter
Hey I'm sorry that I couldn't write any earlier because I had not much time the past few weeks.
I got the information about the tweeter by calling kef! They simply told me that this is the corresponding tweeter and that Sp1542 is its number.
It seams like every part you can buy separate for servicing and repair got its own number.
Sure I know that you just need one tweeter thats placed in the middle of the bass-mid driver but I haven't got those, I just got the driver.
I'm hoping you got any further with testing because I cant wait any longer to get them finished.
I am sorry that I can't provide you with a picture, but I didn't received the tweeters jet.
You know witch frequency the crossover-cut is? I am thinking about rebuilding the original crossover, because I don't want you to hurry with your result.
Just take your time! Maybe I will change the crossover when your done.
ligger
Hey I'm sorry that I couldn't write any earlier because I had not much time the past few weeks.
I got the information about the tweeter by calling kef! They simply told me that this is the corresponding tweeter and that Sp1542 is its number.
It seams like every part you can buy separate for servicing and repair got its own number.
Sure I know that you just need one tweeter thats placed in the middle of the bass-mid driver but I haven't got those, I just got the driver.
I'm hoping you got any further with testing because I cant wait any longer to get them finished.
I am sorry that I can't provide you with a picture, but I didn't received the tweeters jet.
You know witch frequency the crossover-cut is? I am thinking about rebuilding the original crossover, because I don't want you to hurry with your result.
Just take your time! Maybe I will change the crossover when your done.
ligger
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