Being one of the best sounding speaker kits back in 1983's one can make - or so they claimed and it had a good reputation. It was called Hifi 60/4 (meaning 60 litres and 4 drivers). Vifa P21rex woofer, Peerless KO40mrf mids and Dynaudio D21 tweeter. The thing is designed to give smooth overall response in a typical room environment to a listening position as well as to give deep bass response down to 25Hz or so. Crossover freq: 500 and 5000Hz.
Anyway I just finished the first one and took a quick listening session. No, this cant be true, how can one even listen to this speaker as it is? It sounded just horrible! Midrange was badly peaking and one notey. That was not what I was hoping for.
There must be something wrong but I dont know what exactly. I took some measurements from the midranges with and without crossover (measured at 1meter distance).
Here are the results:
Waterfall (some weird things happening):
So as can be seen, it is heavily peaking around 3kHz. Even worse with crossover. Any idea what is going on there?
Here is the speaker itself and some measurements by the hifi-magazine which is the source for this speaker kit.
And finally the crossover:
Anyway I just finished the first one and took a quick listening session. No, this cant be true, how can one even listen to this speaker as it is? It sounded just horrible! Midrange was badly peaking and one notey. That was not what I was hoping for.
There must be something wrong but I dont know what exactly. I took some measurements from the midranges with and without crossover (measured at 1meter distance).
Here are the results:
Waterfall (some weird things happening):
So as can be seen, it is heavily peaking around 3kHz. Even worse with crossover. Any idea what is going on there?
Here is the speaker itself and some measurements by the hifi-magazine which is the source for this speaker kit.
And finally the crossover:
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Well Vituixcad seems to indicate and basically match your measurements which highlight the issue you have .
My first reaction was maybe a phase reversal or old drivers with stiff suspensions.
But your graphs suggest to me that maybe some more refinement of the roll on of both Midranges will get you a better frequency response.
The staggered two midrange drivers do seem slightly odd, Is that in fact the problem that they should be in parallel not series as you have shown.
My first reaction was maybe a phase reversal or old drivers with stiff suspensions.
But your graphs suggest to me that maybe some more refinement of the roll on of both Midranges will get you a better frequency response.
The staggered two midrange drivers do seem slightly odd, Is that in fact the problem that they should be in parallel not series as you have shown.
They are designed to be in series according to original manual/schematic. As can be seen the lower midrange driver has 10uF capacitor accross it to prevent comb filtering at high frequencies beetween the two midrange drivers. I did take it off but did not make much difference for this particular problem.
I have 4 x KO40 midranges having brand new suspensions but they are actually worse 😀
Ok, that clears the circuit question up.
I would play with the midrange and see if you cannot get more sensitivity and fill in the gap.
Can you share the vituixcad project?
Ok I redesigned the crossover for mid and tweeter for better match beetween the drivers and some minor slope adjustments (will do some more fine tuning tho..). Now these speakers are starting to sound as they should. Very enjoyable indeed! Articulative and yet still neutral overall. Very very deep bass response, goes easily down to 20Hz with good authority! Thanks to controlled horizonal dir. pattern it gives so much more details that can be heard easily - speakers appears to be closer than they actually are.
Those original Dynaudio D21 drivers were faulty. I removed original drivers (back chamber, magnet and coil/dome assembly) and installed bare 3/4" (same size as original domes) neodymium dome tweeters to the "horns". They work very well and as the crossover freq is as high as 5kHz I think there is no need for large back chamber anyway? At least good enough at this point but I'm still looking for proper replacements for D21's.
Here is the room response at my listening position, distance is about 2 meters from the speakers. Not too bad at this point but ofcourse there are some room modes at lower frequencies.. Anyway it pretty much matches the original "facrory" response (seen on my first post).
All I can say this is highly recommended design if one can find new suitable drivers. Those originals are now quite obsolete and pretty hard to find.. Also the crossover needs to be redesigned for any different drivers.
Those original Dynaudio D21 drivers were faulty. I removed original drivers (back chamber, magnet and coil/dome assembly) and installed bare 3/4" (same size as original domes) neodymium dome tweeters to the "horns". They work very well and as the crossover freq is as high as 5kHz I think there is no need for large back chamber anyway? At least good enough at this point but I'm still looking for proper replacements for D21's.
Here is the room response at my listening position, distance is about 2 meters from the speakers. Not too bad at this point but ofcourse there are some room modes at lower frequencies.. Anyway it pretty much matches the original "facrory" response (seen on my first post).
All I can say this is highly recommended design if one can find new suitable drivers. Those originals are now quite obsolete and pretty hard to find.. Also the crossover needs to be redesigned for any different drivers.
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