HiFi World (March 2009) had an artical on A25's and building reproduction speakers of them.
The author shows a graph that shows the A25's having about a -7 dB frequency notch at 2.2Khz when the grills were off.
He figures this was due to interference from the edges of the cabinet when the grills were off.
When the grills were put back on, the -7 dB notch moved up to 4KHz.
Think this would account for the upper mid's being recessed a bit.
Thanks for all your input, people. Just a quick post to let you know i'm still paying attention, but it's a bit late and past my bed time so i'll have to be brief! I have had another play with the x-overs and I am very happy with the sound i am getting out of them, even after weeks of quite intensive listening. They're not perfect (what is?) but they are - in my humble opinion - bloody good. I'll write more tomoz. Nighty, night!
Sorry i've taken so long to get back to you all. Been experimenting as ever, and i finally think i've got a result that i'm happy with.
Anyway, here's where i'm up to.
Ditched the 2nd order crossover, as it was flattening depth info, and gone back to 1st order, but altered some values in the process.
The L-pad has been dumped. I'll explain why.
Is it me, or do L-pads screw with the sound? I always find that they seem to lop off some of the air and sparkle in the high treble. I know that they are meant to be purely resistive, but they never sound right to me somehow.
Anyway, the original series resistor appeared to be too high in value to be just attenuation. Had to be some response-shaping going on there as well, so I worked out the actual series value needed to match the 15 ohm parallel and subtracted it from the total series resistance. Leaves me with about 2.8 ohms series resistance. Also, i've increased the series cap value to 6.1uF by using 2.2uF & 3.9uF Audyn-Cap KPSNs in parallel. Bloody good caps, the KPSNs. Built like bullets, and just as heavy, due to the tin foil windings in 'em. Sound nice and clean as well.
In the end, i've actually reduced the number of components in the crossover from three to two (counting the paralleled caps as one of course). So the total component layout in the cabs is a T29CF001 tweeter and a 25TV-EW woofer, 6.1uF of series capacitance and 2.8ohms series resistance for the tweeter and the woofer is connected directly-no attenuation at all.
So how does it sound? With the speakers on stands with the tweeters at ear level, set roughly 2 metres apart, 0.5 metres from the back wall, and toed in with their axes crossing about a metre behind my head, they sound bloody good, as it happens! Plenty of projection for vocals to sit nicely in front of placed instruments within a reasonably deep soundstage. Treble is extended in both directions, with plenty of top end and air, but goes down enough for cymbal tones to register properly. (The number of speakers i have heard that make cymbals all sound the bloody same is countless! Being a drummer, that has always bugged me.) Bass isn't the deepest ever, but what it does reach down to is really even, controlled and tuneful.
Anyway, integration between the drivers sounds very nice to me, with no obvious peaking or steps in the frequency range that I can detect. Overall, the sound has a lovely tonality with good weight and scale, but is incredibly easy to listen to. I'm made up with them!
Anyway, here's where i'm up to.
Ditched the 2nd order crossover, as it was flattening depth info, and gone back to 1st order, but altered some values in the process.
The L-pad has been dumped. I'll explain why.
Is it me, or do L-pads screw with the sound? I always find that they seem to lop off some of the air and sparkle in the high treble. I know that they are meant to be purely resistive, but they never sound right to me somehow.
Anyway, the original series resistor appeared to be too high in value to be just attenuation. Had to be some response-shaping going on there as well, so I worked out the actual series value needed to match the 15 ohm parallel and subtracted it from the total series resistance. Leaves me with about 2.8 ohms series resistance. Also, i've increased the series cap value to 6.1uF by using 2.2uF & 3.9uF Audyn-Cap KPSNs in parallel. Bloody good caps, the KPSNs. Built like bullets, and just as heavy, due to the tin foil windings in 'em. Sound nice and clean as well.
In the end, i've actually reduced the number of components in the crossover from three to two (counting the paralleled caps as one of course). So the total component layout in the cabs is a T29CF001 tweeter and a 25TV-EW woofer, 6.1uF of series capacitance and 2.8ohms series resistance for the tweeter and the woofer is connected directly-no attenuation at all.
So how does it sound? With the speakers on stands with the tweeters at ear level, set roughly 2 metres apart, 0.5 metres from the back wall, and toed in with their axes crossing about a metre behind my head, they sound bloody good, as it happens! Plenty of projection for vocals to sit nicely in front of placed instruments within a reasonably deep soundstage. Treble is extended in both directions, with plenty of top end and air, but goes down enough for cymbal tones to register properly. (The number of speakers i have heard that make cymbals all sound the bloody same is countless! Being a drummer, that has always bugged me.) Bass isn't the deepest ever, but what it does reach down to is really even, controlled and tuneful.
Anyway, integration between the drivers sounds very nice to me, with no obvious peaking or steps in the frequency range that I can detect. Overall, the sound has a lovely tonality with good weight and scale, but is incredibly easy to listen to. I'm made up with them!
i just picked up a very nice pair of A-25"s, and i am also extremely impressed. I have vent at the bottom and no switch?knob on the back. I belive they contain the original drivers, tho the magnet seems larger than normal. Have read most of the threads i can find and have a couple of questions.
How is every body setting them up? I have a terrible listening room and at present have them on two ikea end table about a foot from the wall and 8 foot apart, one in a corner
Is it worth redoing the cross over?
They really do sound great tho...
How is every body setting them up? I have a terrible listening room and at present have them on two ikea end table about a foot from the wall and 8 foot apart, one in a corner
Is it worth redoing the cross over?
They really do sound great tho...
I have a question for the A25 experts regarding the A25X. This version has the port at the top and has the scan drivers. Sounds great in my small room at fairly low volumes, which is what I need.
Thing is I bought the seas hf drivers as recommended on Madisons before I realised I have the scan drivers. If I put the new hf drivers in will the crossover need to be fiddled with? I'd hate to let the magic out of the box if the scan tweeters are anything special.
There is not much around on this A25X that I can find. Any info appreciated.
Thing is I bought the seas hf drivers as recommended on Madisons before I realised I have the scan drivers. If I put the new hf drivers in will the crossover need to be fiddled with? I'd hate to let the magic out of the box if the scan tweeters are anything special.
There is not much around on this A25X that I can find. Any info appreciated.
maybe this will be of some use :
http://www.diyaudio.com/forums/multi-way/11044-old-scan-speak-drivers.html#post127406
http://www.diyaudio.com/forums/multi-way/11044-old-scan-speak-drivers.html#post127406
Shortly after my last post, i took the original series cap back to 5uF - slightly more distant presentation but even more coherence - and I haven't felt the need to mess around with them since. Whenever I get the chance, i just chuck some cds on and enjoy!
As regards the old Scan tweeters, if it's possible to retrofit them after trying the SEAS units, then you can't lose out by trying the newer units. I only needed to make a couple of small adjustments in the tweeter cutout to accomodate the wider spacing of the new unit's terminals. In the event of my wanting to put the old units back in, then their faceplace would cover the new cutouts anyway. I don't think that the Scans were that different to the equivalent SEAS driver of the day anyway, so i would say go for it.
Finally, when i took the original crossover units out of my cabs, i found old Jensen reversible electrolytics in there. Having been installed in the 70's they had dryed out and gone way off spec, so if yours are similar, then get your soldering iron out. Good luck and have fun!
As regards the old Scan tweeters, if it's possible to retrofit them after trying the SEAS units, then you can't lose out by trying the newer units. I only needed to make a couple of small adjustments in the tweeter cutout to accomodate the wider spacing of the new unit's terminals. In the event of my wanting to put the old units back in, then their faceplace would cover the new cutouts anyway. I don't think that the Scans were that different to the equivalent SEAS driver of the day anyway, so i would say go for it.
Finally, when i took the original crossover units out of my cabs, i found old Jensen reversible electrolytics in there. Having been installed in the 70's they had dryed out and gone way off spec, so if yours are similar, then get your soldering iron out. Good luck and have fun!
I've been experimenting again! Move of house facilitated it, as the sound in the new room is far different to the old one. Firstly, had to invest in an old-but-good M&K V75 sub, cos the bass end drops off like a stone below 80-ish Hz. Then, on a hunch, fitted a 1uF and a 0.68uF in series with the tweeter and NO attenuation. Woah! Even more coherence, a lovely extended treble, and loads of stage depth, with vocals nicely up front.
Decided to upgrade the caps from Claritycap SA's to Jantzen Audio Silver Z-caps, (combo of 1.5uF and 0.15uF). Initially, results were mixed; the sheer blackness of space between instruments and obvious lack of compression and 'fizz' in the sound compared to the SA's was astounding. However, the top end had become a bit too forward and soundstage depth had diminished. ESR of the new caps must be lower, so I chucked in 0.47 ohm 10 watt wirewound between the input terminal and the caps. Bingo! This is impressive. Massive soundstage depth, and lovely focus and coherence, with top end on the bright side of neutral. The Jantzens are brilliant caps, way ahead of the Claritycaps, and pretty much everything else i've tried. Next to be upgraded are the bog standard wirewounds to Mundorf M-resist supremes, and they are on order now.
I have to say that this all speaks volumes for the quality of the bass mid. Bang those component specs into a crossover calc and that gives a crossover point for the tweeter of about 22kHz, but I can't detect any integration problems between the units! Speakers are placed roughly 8 foot apart, 2 foot from the back wall, and toed in so that the inner sides of the cabinet are just visible.
Decided to upgrade the caps from Claritycap SA's to Jantzen Audio Silver Z-caps, (combo of 1.5uF and 0.15uF). Initially, results were mixed; the sheer blackness of space between instruments and obvious lack of compression and 'fizz' in the sound compared to the SA's was astounding. However, the top end had become a bit too forward and soundstage depth had diminished. ESR of the new caps must be lower, so I chucked in 0.47 ohm 10 watt wirewound between the input terminal and the caps. Bingo! This is impressive. Massive soundstage depth, and lovely focus and coherence, with top end on the bright side of neutral. The Jantzens are brilliant caps, way ahead of the Claritycaps, and pretty much everything else i've tried. Next to be upgraded are the bog standard wirewounds to Mundorf M-resist supremes, and they are on order now.
I have to say that this all speaks volumes for the quality of the bass mid. Bang those component specs into a crossover calc and that gives a crossover point for the tweeter of about 22kHz, but I can't detect any integration problems between the units! Speakers are placed roughly 8 foot apart, 2 foot from the back wall, and toed in so that the inner sides of the cabinet are just visible.
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Distortion problem with A25 woofer
I bought a pair of A25s on Ebay for cheap because the speaker posts had fallen out. I envisioned fixing them and selling again just so I could hear what they sound like. I fixed them they were working fine. After a few weeks of listening one speaker started getting a lot of distortion. It went away after I moved the speaker to another room. Then It came back again. I think the voice coil is rubbing. I took out the speaker and it buzzes below 200hz using sine wave signals. The glue and cone looks good. I noticed the buzzing appears to do with the speakers upward orientation as you spin it. I didn't notice which way was up When I removed the speakers. The buzzing goes away as I rotate the speakers around. Has anyone noticed this problem with old speakers before? Should I refoam it? I reinstalled the speaker and it is ok for now. I really don't want to put much more money into this project. I want to sell them but I want to make sure they are ok before I do so.
I bought a pair of A25s on Ebay for cheap because the speaker posts had fallen out. I envisioned fixing them and selling again just so I could hear what they sound like. I fixed them they were working fine. After a few weeks of listening one speaker started getting a lot of distortion. It went away after I moved the speaker to another room. Then It came back again. I think the voice coil is rubbing. I took out the speaker and it buzzes below 200hz using sine wave signals. The glue and cone looks good. I noticed the buzzing appears to do with the speakers upward orientation as you spin it. I didn't notice which way was up When I removed the speakers. The buzzing goes away as I rotate the speakers around. Has anyone noticed this problem with old speakers before? Should I refoam it? I reinstalled the speaker and it is ok for now. I really don't want to put much more money into this project. I want to sell them but I want to make sure they are ok before I do so.
Hi,
Rotating old drivers is a well known to some fix.
If it works fine rotated it will get better before
it gets worse, and that could take a long time.
Your good to go to move them on.
rgds, sreten.
The curious prod and probe the surround to see
what is the worst point to cause rubbing, and
then align that point to be at the bottom.
With only 4 screws only 4 points need checking.
Rotating old drivers is a well known to some fix.
If it works fine rotated it will get better before
it gets worse, and that could take a long time.
Your good to go to move them on.
rgds, sreten.
The curious prod and probe the surround to see
what is the worst point to cause rubbing, and
then align that point to be at the bottom.
With only 4 screws only 4 points need checking.
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Hi folks! Just an update on where I am with the system and speaker config.
Well, I've gone full circle and reverted to the original l-pad (3.9 ohms series and 15 in parallel) as it works best with the Rega DAC-R that I recently acquired. The series cap for the tweeter is now a 4.7uF Jantzen Silver Z cap. I can't recommend these highly enough. A massive improvement over the previous caps, with loads of air and detail coming through.
Well, I've gone full circle and reverted to the original l-pad (3.9 ohms series and 15 in parallel) as it works best with the Rega DAC-R that I recently acquired. The series cap for the tweeter is now a 4.7uF Jantzen Silver Z cap. I can't recommend these highly enough. A massive improvement over the previous caps, with loads of air and detail coming through.
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