I measured the Qt of the AE1s and they came up as 0.478, with a maximum impedance of 45.4 ohm with a minimum of 8.1. Fs was at 62.7 Hz.
I managed to toast my AKSA amp in process, but fortunately the damage was just a resistor and fuse. Mental note: make sure multimeter leads are not plugged into current measuring terminals when checking voltage across speaker terminals.
Because of the very gentle roll off of the AE1s, I think that I may need to reduce the volume of the boxes somehow if I'm going to lower the XO frequency, otherwise it will be too hard to get a nice rolloff symmetrical to the bass speakers. Maybe I could add some inserts into the box to make it taper towards the back. Any thoughts on that one? Does a Q of 0.7 give the same shaped rolloff as a L-R 12 DB/Oct filter?
Mick
I managed to toast my AKSA amp in process, but fortunately the damage was just a resistor and fuse. Mental note: make sure multimeter leads are not plugged into current measuring terminals when checking voltage across speaker terminals.
Because of the very gentle roll off of the AE1s, I think that I may need to reduce the volume of the boxes somehow if I'm going to lower the XO frequency, otherwise it will be too hard to get a nice rolloff symmetrical to the bass speakers. Maybe I could add some inserts into the box to make it taper towards the back. Any thoughts on that one? Does a Q of 0.7 give the same shaped rolloff as a L-R 12 DB/Oct filter?
Mick
Having soldered some flying leads onto the XO, I have spent a fair bit of time trying different XO frequencies over the last few weeks, and discovered all sorts of interesting things.
By testing the response of the bass speakers and the AE1s separately, I discovered that the deep knotch that I have at 192 Hz is not due to floor bounce but a vertical room mode. It mainly occurs in the bass speaker, and the AE1 bass driver, which is only around 30cm higher is almost free of it. So changing the XO frequency down a lot helped get rid of this knotch, which was hearable as a lack of mid bass.
I tried frequencies as high as 380 Hz, and then 300 Hz, 228Hz, 200 Hz, 170 Hz, and 130 Hz. Basically as I went lower things got better. At higher frequencies the sound was a bit warmer, and with the bass knotch problem, but not so focussed or well articulated. At the lowest frequency (where it remains now) of 130 Hz, the sound was more focussed, and had more fine detail that allows you to hear individual instruments in a orchestral piece more clearly, and imaged better.
Over the last couple of days I managed to get some proper plugs soldered onto the pre-power leads from the amp, so I could test the AE1s on their own (with ports open) vs with the bass speaker (with ports stuffed).
There's definitely a big increase in the amount of bass present with the new bass speakers, even the the in-room extension is only about 50 Hz, due a bit of a room dip around this frequency. However the bass sounds a bit wooley and slow to me, as though it is lagging the rest of the music. I can't figure this one out, as they are excellent drivers in a well damped sealed enclosure. Maybe the room walls is vibrating too much
Unfortunately the active XO and the bass speaker has subtracted something from the mids and highs. Its the same kind of effect with changing the XO frequency. I'm missing some of the focus, and fine detail compared with running the AE1s on their own.
Another experiment that I tried was to have the AE1s running full range, and then running through the active XO with a frequency cutoff of 130 Hz, but with no bass speaker running. Apart from the reduction in bass, again I was missing some of the focus and fine detail, but fairly subtle now.
So next stop will probably to try the AE1s full range with ports stuffed and just have the bass speakers cutting off at around 70 or 80 Hz at 12 dB/Oct. Maybe I should have listed to RodYama's suggestions a month ago...
Mick
By testing the response of the bass speakers and the AE1s separately, I discovered that the deep knotch that I have at 192 Hz is not due to floor bounce but a vertical room mode. It mainly occurs in the bass speaker, and the AE1 bass driver, which is only around 30cm higher is almost free of it. So changing the XO frequency down a lot helped get rid of this knotch, which was hearable as a lack of mid bass.
I tried frequencies as high as 380 Hz, and then 300 Hz, 228Hz, 200 Hz, 170 Hz, and 130 Hz. Basically as I went lower things got better. At higher frequencies the sound was a bit warmer, and with the bass knotch problem, but not so focussed or well articulated. At the lowest frequency (where it remains now) of 130 Hz, the sound was more focussed, and had more fine detail that allows you to hear individual instruments in a orchestral piece more clearly, and imaged better.
Over the last couple of days I managed to get some proper plugs soldered onto the pre-power leads from the amp, so I could test the AE1s on their own (with ports open) vs with the bass speaker (with ports stuffed).
There's definitely a big increase in the amount of bass present with the new bass speakers, even the the in-room extension is only about 50 Hz, due a bit of a room dip around this frequency. However the bass sounds a bit wooley and slow to me, as though it is lagging the rest of the music. I can't figure this one out, as they are excellent drivers in a well damped sealed enclosure. Maybe the room walls is vibrating too much
Unfortunately the active XO and the bass speaker has subtracted something from the mids and highs. Its the same kind of effect with changing the XO frequency. I'm missing some of the focus, and fine detail compared with running the AE1s on their own.
Another experiment that I tried was to have the AE1s running full range, and then running through the active XO with a frequency cutoff of 130 Hz, but with no bass speaker running. Apart from the reduction in bass, again I was missing some of the focus and fine detail, but fairly subtle now.
So next stop will probably to try the AE1s full range with ports stuffed and just have the bass speakers cutting off at around 70 or 80 Hz at 12 dB/Oct. Maybe I should have listed to RodYama's suggestions a month ago...
Mick
Mick,
Thanks for sharing your findings . In a sense you plan on going a 2.5 route instead of a 3 way, running the tm full range and then rolling the woofer off with passive or active xo ?
jean
Thanks for sharing your findings . In a sense you plan on going a 2.5 route instead of a 3 way, running the tm full range and then rolling the woofer off with passive or active xo ?
jean
Jean
I don't think that what I am planning is a 2.5 way, as the mid will roll off naturally with an XO frequency of about 70 Hz, at which point the bass speaker will take over. So the drivers are only reproducing the same frequencies over the region of the XO overlap.
In your project you found that 80Hz was a good cutoff point from memory. What were your listening impressions of the changes with the XO frequency?
Unfortunately I haven't been able to try what I was planning, as with the current active XO configuration I can only change the level of the HP output, and as I won't be using the HP output from the XO any more then I can adjust level between the bass speaker and the AE1s. So I need to add an extra level control.
Eric - are you talking about the TimeAlign technology? This doesn't really tell you much about what they are doing, does it?
Mick
I don't think that what I am planning is a 2.5 way, as the mid will roll off naturally with an XO frequency of about 70 Hz, at which point the bass speaker will take over. So the drivers are only reproducing the same frequencies over the region of the XO overlap.
In your project you found that 80Hz was a good cutoff point from memory. What were your listening impressions of the changes with the XO frequency?
Unfortunately I haven't been able to try what I was planning, as with the current active XO configuration I can only change the level of the HP output, and as I won't be using the HP output from the XO any more then I can adjust level between the bass speaker and the AE1s. So I need to add an extra level control.
Eric - are you talking about the TimeAlign technology? This doesn't really tell you much about what they are doing, does it?
Mick
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