I use these speakers and having external crossovers I rather fancy trying to use them as the Dynaco A25s were wired - virtually crossoverless save a cap for the tweeter.
The cap in the original kit is 10.1pF. My amp is a Sugden a21SE.
Am I likely to blow them up or might it just work ?
Crossoverless WD25TEx
#2
Keep the levels sane, and you won't blow them up.
Chances are you'll get a load of mush in the midrange from that big woofer's breakup, plus running the tweeter low = increased harmonic distortion.
I wouldn't bother myself, but if you fancy an experiment, go right ahead.
Chris
Chances are you'll get a load of mush in the midrange from that big woofer's breakup, plus running the tweeter low = increased harmonic distortion.
I wouldn't bother myself, but if you fancy an experiment, go right ahead.
Chris
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Scottmoose
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#3
The A26 doesn't have a big HF resonant mode as far as I know: http://www.seas.no/index.php?option=com ... Itemid=461 -progressive rolloff with well controlled breakup, yes. They do something akin themselves http://www.seas.no/index.php?option=com ... Itemid=365 -spiritual successor of both the Dynaco A25 & the WD25. Not an approach I like all that much, since a 10in midbass is never going to match a quality tweeter or smaller midbass driver for refined midband, but it should have a nice 'vintage' tone to it, & be a pleasant listen once dialled in well.
Power handling will be rather more limited with your tweeter, with greater distortion, as Chris notes. Seas tweeters in general & the Millennium in particular can take a bit of stick though, so providing you don't expect miracles (you need 2nd order or variable rate slopes to prevent excursion increasing < the XO frequency) and keep the volume down, you're not likely to fry things. Cap value should be chosen for the optimal XO frequency & the driver's impedance at that of course. You may also need a level padding resistor for the tweeter.
Power handling will be rather more limited with your tweeter, with greater distortion, as Chris notes. Seas tweeters in general & the Millennium in particular can take a bit of stick though, so providing you don't expect miracles (you need 2nd order or variable rate slopes to prevent excursion increasing < the XO frequency) and keep the volume down, you're not likely to fry things. Cap value should be chosen for the optimal XO frequency & the driver's impedance at that of course. You may also need a level padding resistor for the tweeter.
#4
Well, I must have lousy lugs, I guess. All I´ve done is bypass the bass part of the crossover circuit but leaving it in place. I´m afraid it sounds rather nice, especially the mid band. Low level detail that I had to stretch to hear before is all there and I don´t seem to have lost anything on the way. I was very surprised when I listened to Brahm´s violin concerto and the general spatial representation of the orchestra as a whole was much improved plus previously unheard low detail e.g. tympani rolls just before the entrance of the violin at the beginning. Let´s see if it doesn´t all fall apart when I get to removing the crossover completely.
#5
When you say "remove the crossover completely" do you really mean providing no tweeter protection at all? That's almost certain to fry the tweeter in next to no time at all I'm afraid. Also, in your opening post, was the 10.1pF really the correct value or did you mean 10.1uF?
I'm with Scottmoose here. The driver choice and crossover approach is one that I don't favour for several reasons. Depending on the crossover frequency, a large 10 inch is likely to start beaming as low as 1.3KHz and looking at the driver response, that woofer looks best crossed over below 1kHz which is very low indeed for any tweeter to take on, so likely to be designed for on axis listening in a 2-way if crossed over higher up.
Using 6dB/octave slopes also generates lots of overlap which I personally find mucks up mid clarity and extends the band in which comb filtering (due to relative phase relationship) can occur even with accurately set values. I'd be more likely to use 12 or 18dB slopes for a lowish crossover of around 2KHz and even then, be using a notch filter for the tweeter to quash its impedance peak at resonance. No reason, if properly done why it can;t be more coherent than the simpler approach, and produce greater clarity.
The woofer natural rolloff looks close to 6dB/octave, so for a 2KHz crossover, I'd probably be using a mixed electrical crossover consisting of an inductor for the woofer (to get an acoustic 12dB slope) and a cap and shunt inductor for the tweeter for a matched 12dB/octave acoustic slope.
Whatever sounds best to you though. Just be careful with that tweeter!
I'm with Scottmoose here. The driver choice and crossover approach is one that I don't favour for several reasons. Depending on the crossover frequency, a large 10 inch is likely to start beaming as low as 1.3KHz and looking at the driver response, that woofer looks best crossed over below 1kHz which is very low indeed for any tweeter to take on, so likely to be designed for on axis listening in a 2-way if crossed over higher up.
Using 6dB/octave slopes also generates lots of overlap which I personally find mucks up mid clarity and extends the band in which comb filtering (due to relative phase relationship) can occur even with accurately set values. I'd be more likely to use 12 or 18dB slopes for a lowish crossover of around 2KHz and even then, be using a notch filter for the tweeter to quash its impedance peak at resonance. No reason, if properly done why it can;t be more coherent than the simpler approach, and produce greater clarity.
The woofer natural rolloff looks close to 6dB/octave, so for a 2KHz crossover, I'd probably be using a mixed electrical crossover consisting of an inductor for the woofer (to get an acoustic 12dB slope) and a cap and shunt inductor for the tweeter for a matched 12dB/octave acoustic slope.
Whatever sounds best to you though. Just be careful with that tweeter!
#6
When you say "remove the crossover completely" do you really mean providing no tweeter protection at all? That's almost certain to fry the tweeter in next to no time at all I'm afraid. Also, in your opening post, was the 10.1pF really the correct value or did you mean 10.1uF?
I'm with Scottmoose here. The driver choice and crossover approach is one that I don't favour for several reasons. Depending on the crossover frequency, a large 10 inch is likely to start beaming as low as 1.3KHz and looking at the driver response, that woofer looks best crossed over below 1kHz which is very low indeed for any tweeter to take on, so likely to be designed for on axis listening in a 2-way if crossed over higher up.
Using 6dB/octave slopes also generates lots of overlap which I personally find mucks up mid clarity and extends the band in which comb filtering (due to relative phase relationship) can occur even with accurately set values. I'd be more likely to use 12 or 18dB slopes for a lowish crossover of around 2KHz and even then, be using a notch filter for the tweeter to quash its impedance peak at resonance. No reason, if properly done why it can't be more coherent than the simpler approach, and produce greater clarity.
The woofer natural roll-off looks close to 6dB/octave, so for a 2KHz crossover, I'd probably be using a mixed electrical crossover consisting of an inductor for the woofer (to get an acoustic 12dB slope) and a cap and shunt inductor for the tweeter for a matched 12dB/octave acoustic slope.
Whatever sounds best to you though. Just be careful with that tweeter!
I'm with Scottmoose here. The driver choice and crossover approach is one that I don't favour for several reasons. Depending on the crossover frequency, a large 10 inch is likely to start beaming as low as 1.3KHz and looking at the driver response, that woofer looks best crossed over below 1kHz which is very low indeed for any tweeter to take on, so likely to be designed for on axis listening in a 2-way if crossed over higher up.
Using 6dB/octave slopes also generates lots of overlap which I personally find mucks up mid clarity and extends the band in which comb filtering (due to relative phase relationship) can occur even with accurately set values. I'd be more likely to use 12 or 18dB slopes for a lowish crossover of around 2KHz and even then, be using a notch filter for the tweeter to quash its impedance peak at resonance. No reason, if properly done why it can't be more coherent than the simpler approach, and produce greater clarity.
The woofer natural roll-off looks close to 6dB/octave, so for a 2KHz crossover, I'd probably be using a mixed electrical crossover consisting of an inductor for the woofer (to get an acoustic 12dB slope) and a cap and shunt inductor for the tweeter for a matched 12dB/octave acoustic slope.
Whatever sounds best to you though. Just be careful with that tweeter!
#7
Hi, Thanks for the input. Indeed what I meant when I said "remove the crossover" was to remove the present, rather complicated to me, third order crossover. Yes, I do intend to protect the tweeter with a cap. Yes, I did mean 10.1uF value.
All I can say is that the midband hash has not increased - quite the opposite, I would say so far. Let´s´see how it sounds when I try the treble crossover part this weekend.
Thanks again.
Chris
P.S. Of course, after thinking it over a bit, it´s always possible that the 3rd order crossovers were not working properly for some reason. I´ll check them while I´m testing the alternative first order one.
All I can say is that the midband hash has not increased - quite the opposite, I would say so far. Let´s´see how it sounds when I try the treble crossover part this weekend.
Thanks again.
Chris
P.S. Of course, after thinking it over a bit, it´s always possible that the 3rd order crossovers were not working properly for some reason. I´ll check them while I´m testing the alternative first order one.
#8
Keep us informed as I'd be interested to hear how you get on. It might be possible that there was fault somewhere, as properly designed, I would have thought that a properly designed acoustic 3rd order x-over would have been a good option for such a driver complement.VantheMan wrote:Hi, Thanks for the input. Indeed what I meant when I said "remove the crossover" was to remove the present, rather complicated to me, third order crossover. Yes, I do intend to protect the tweeter with a cap. Yes, I did mean 10.1uF value.
All I can say is that the midband hash has not increased - quite the opposite, I would say so far. Let´s´see how it sounds when I try the treble crossover part this weekend.
Thanks again.
Chris
P.S. Of course, after thinking it over a bit, it´s always possible that the 3rd order crossovers were not working properly for some reason. I´ll check them while I´m testing the alternative first order one.
#9
Well, I have had very little time this month but I now have some 4.7uF Auricaps on the tweeter and the woofers are connected direct. I quite like the change bass-wise, more of it , deeper and easier to follow and do not detect any overt mush in the mids so the 2KHz crossover point is not a problem especially since I switched the tweeter phase connection but I would like a bit more razzamataz to the sound. I am thinking of trying the 10.1uF value that Comeau used on the tweeter in the original crossover although of course I will need a 6.8 and 3.3 parallel combo. Is it likely that raising this value to 10.1uF might help to bring out the surprise factor (mids, I guess) any or am I barking up the wrong tree ? Suck it and see, I suppose.
#10
Well, I have now tried with the woofer connected direct and 4.7uF, then 6.8uF and finally 9.0uf caps on the tweeter and it has got progressively better (I think) but I can´t help thinking I´m wasting my time. There is something essentially NOT right about it (maybe because in the case of my boxes, the aperiodic port leads to another chamber within a sealed box whereas the A25´s aperiodic port lead out to free air. I can´t put my finger on it but there are no fireworks or surprises to the sound so maybe I´m getting as predicted, a pleasant vintage sort of sound and the mids are just getting more or less murky. I shall be going back to the original crossovers but I have learnt from reading comments by Comeau himself that by playing with the R3 resistor on the tweeter inductor I can alter the transfer curve (?) and get a slightly warmer sound, so I shall probably try that.
Had I not built my crossovers in external boxes I would never have been able to scratch this itch so all´s well that ends well .... or maybe not.
Had I not built my crossovers in external boxes I would never have been able to scratch this itch so all´s well that ends well .... or maybe not.
#11
Well, I have gone back to the old crossover values, having changed to Mills 12w wirewounds for the 2R2 resistor in series with the tweeter inductor and the 27R between the tweeter terminals and they sound great. I won't be experimenting any more with the designer's original values but I might try a few more Mills in the Xovers - they certainly seem to have improved things over the ceramic and the Panasonic 5W ones, they replaced.