navin said:
Hi,
I chose the PLL filter because it is reversible, and "tweakable". You can adjust the values until you achieve the sound you like. Phase plugs may fare better, but once you cut the dustcap, there's no way back. I am quite happy with Geoff's circuit:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=99662&highlight=
No, I am not using a tweeter, and don't feel a need for one. Some people have tried Visaton B200 with tweeters, and, were not happy with the result...
Regards,
Vix
Eureka! I just discovered hot water! 
Ok, a joke aside. I just discovered something that OB folks already know, but to me it was striking because I did not expect such an effect.
Yesterday I removed side wings from the left OB speaker...My wife was assisting me and holding the baffle (since the baffle lost its support from the side wings)...
The result was
I suspected that Visaton NoBox design which I copied has the side wings that are bigger than I would like, but I could have never assumed that it would impact the sound that much...
Without side wings, the sound opened up, now it really became OB sound...
The main problem with side wings was that it generated some resonance it the mid-bass, making it sound bloated and muddy...
Without wings, bass quantity decreased, quality increased. But it was worth it.
If you are running simple OBs there is a tendency to make U or H frame for the bass to increase the extension. But, as it turned out to be in my case, improper wings, (or U or H frame I guess) will introduce some resonances and color the sound , diminishing its quality...
Ok, a joke aside. I just discovered something that OB folks already know, but to me it was striking because I did not expect such an effect.
Yesterday I removed side wings from the left OB speaker...My wife was assisting me and holding the baffle (since the baffle lost its support from the side wings)...
The result was
I suspected that Visaton NoBox design which I copied has the side wings that are bigger than I would like, but I could have never assumed that it would impact the sound that much...
Without side wings, the sound opened up, now it really became OB sound...
The main problem with side wings was that it generated some resonance it the mid-bass, making it sound bloated and muddy...
Without wings, bass quantity decreased, quality increased. But it was worth it.
If you are running simple OBs there is a tendency to make U or H frame for the bass to increase the extension. But, as it turned out to be in my case, improper wings, (or U or H frame I guess) will introduce some resonances and color the sound , diminishing its quality...
I really doubt that you had any resonances due to the side wings. The acoustic impedance of the large open back should be enough to totally damp any potential resonances. My guess is that when you removed the wings you changed the tuning of the bass, not as deep but probably more efficient, which in turn changed the SPL balance of your system. If it sounds better that is all that really matters.
Vix said:
Thanks for the positive feedback.
One of the biggest misconceptions about OBs with wings is that they will create resonances. A winged OB is open at the top unlike a H or U frame. MY FE analyses of the geometry show that resonances will not happen. Skorpion posted some measurements on AudioCircle that backed up these calculations. I think in general people quickly blame resonances when something does not sound right with an OB (or even a boxed speakers), I believe that in most cases resonances are not to blame for an OB's sound and that something simple has impacted the SPL balance of the system..
Sooner or later I will put together some documentation of my experiences with active/biamped OB systems. It will probably be later since I am now working on other things.
navin said:
Well, meybe its a hard word to call them "improper". The wings on the Visaton NoBox design extend all the way up, and, despite the act that they increase the effective baffle area, they seemed to affect the tonal balance in a negative way. In my case, they were adding some midbass peak, that was obscuring other bass notes.
I guess that small wings are beneficial, but if they are large, that sounds no good.
Maybe all this has to do with the room size and speaker distance to the back wall. Recently I've moved to a smaller apartment. Listening room is 4x4 m. OB's are placed around 60 cm from the back wall (I can move them up to 1 m). Without wings, OB's have more "breathing" space....
navin said:
1. Look here: http://www.enjoythemusic.com/magazine/equipment/0606/visation_nobox_bb_loudspeaker.htm
2. No.
3. I have no sub. Visaton is Hi-passed at 200 Hz 6db/oct via passive line level (just an input cap); Eminence is LP at 100 Hz 12 db/oct. Active crossover. Biamped.
Hi,
Since I've built them, I haven't stopped playing with my OB's.
1.I removed the side wings.
The result: Without side wings, it sound much more open and relaxing. A side wing covering a midrange driver (Visaton B200) is a no no. Of course, bass is weaker, but the overall sound is more pleasing. Eventually, I may try some small "short" wings, covering just the woofer, but not any higher.
2.Visaton B200 got its dust cup cuttted off, and I installed a "mock up" phase plug (you'll laugh at this, I put a candle instead). This definitely improved the sound of Visation, but it still needed some notch filtering. I installed a 0.68 mH inductror in paralel with 7 ohm resistor ( value obratined by parallel connection of several various values), so now it sounds very balanced.
3.Crossover. So far, what works best is a 100 hz/12 db Linkwitz Riley alignment, both HP and LP. (Thank you Nelson for the tip!)
Just yesterday I tried 200 Hz/18 dB for a low pass and 200 Hz/6db for a high pass, but it didn't combine very well. It sounded somewhat muddy, there was plenty of bass, but there was a lack of definition and the drums sounded as they were all over the place. I guess it has to do with the phase variations/anomalities. So I went back to the 100 Hz/ 12db oct setting and I am convinced that this is the value that works best here.
What next? I need to improve a buffer circuit that I used in the active crossovers. Neson Pass will pulish the buffer circuit so I hope to utilize that one....
Even though Open baffles turned out to be a tough lesson, they will stay...
Box speakers? Sometimes, just to feel how good OB's are...
Regards,
Vix
Since I've built them, I haven't stopped playing with my OB's.
1.I removed the side wings.
The result: Without side wings, it sound much more open and relaxing. A side wing covering a midrange driver (Visaton B200) is a no no. Of course, bass is weaker, but the overall sound is more pleasing. Eventually, I may try some small "short" wings, covering just the woofer, but not any higher.
2.Visaton B200 got its dust cup cuttted off, and I installed a "mock up" phase plug (you'll laugh at this, I put a candle instead). This definitely improved the sound of Visation, but it still needed some notch filtering. I installed a 0.68 mH inductror in paralel with 7 ohm resistor ( value obratined by parallel connection of several various values), so now it sounds very balanced.
3.Crossover. So far, what works best is a 100 hz/12 db Linkwitz Riley alignment, both HP and LP. (Thank you Nelson for the tip!)
Just yesterday I tried 200 Hz/18 dB for a low pass and 200 Hz/6db for a high pass, but it didn't combine very well. It sounded somewhat muddy, there was plenty of bass, but there was a lack of definition and the drums sounded as they were all over the place. I guess it has to do with the phase variations/anomalities. So I went back to the 100 Hz/ 12db oct setting and I am convinced that this is the value that works best here.
What next? I need to improve a buffer circuit that I used in the active crossovers. Neson Pass will pulish the buffer circuit so I hope to utilize that one....
Even though Open baffles turned out to be a tough lesson, they will stay...
Box speakers? Sometimes, just to feel how good OB's are...
Regards,
Vix
OB's..again
Never stopped playin'...and tweaking...
I was playing with the crossover, trying different settings, listening to that for a few weeks, then changing again...
What works now is: Visaton B200 run fullrange, with the active notch filter (sandwiched between two Firstwatt B1 buffers).
Eminence Beta 15 LP-ed at 45 Hz, 12/db oct.
Some of you may argue that it is not a good idea to run Visaton fullrange, but, at "normal" listening volumes it sounds better, more coherent and more musical. At high volumes, excursion gets unpleasant, but most of the times I don't listen very loud, so I care not.
Eminence Beta 15 just adds a bit of missing bottom end.
Future thoughts: A Step backwards: BOX!
Since my listening room is not big (12x12 feet approx), and due to domestic considerations the baffles are fairly close to the wall (2 feet), I thought about building a sealed box for the Betas, and leave Visatons "open air". Something similar to BassZilla concept...
Regards,
Vix
Never stopped playin'...and tweaking...
I was playing with the crossover, trying different settings, listening to that for a few weeks, then changing again...
What works now is: Visaton B200 run fullrange, with the active notch filter (sandwiched between two Firstwatt B1 buffers).
Eminence Beta 15 LP-ed at 45 Hz, 12/db oct.
Some of you may argue that it is not a good idea to run Visaton fullrange, but, at "normal" listening volumes it sounds better, more coherent and more musical. At high volumes, excursion gets unpleasant, but most of the times I don't listen very loud, so I care not.
Eminence Beta 15 just adds a bit of missing bottom end.
Future thoughts: A Step backwards: BOX!
Since my listening room is not big (12x12 feet approx), and due to domestic considerations the baffles are fairly close to the wall (2 feet), I thought about building a sealed box for the Betas, and leave Visatons "open air". Something similar to BassZilla concept...
Regards,
Vix
Hi Vix,
B**! You using naughty words ? (LOL)
Okay, so you are 'LP'ing pretty low, but can I suggest you make a frame or box that you can place against and take away from the rear of the baffle whilst music is playing.
The only way I have found to be a tonally acceptable for increasing LF output without introducing an additional upper bass peak is by using soft absorbent side panels like cushions, thick felt layers, carpet or quilting.
Either that or another LF driver as well as soft non reflective and non resonant sides.
Cheers ............ Graham.
B**! You using naughty words ? (LOL)
Okay, so you are 'LP'ing pretty low, but can I suggest you make a frame or box that you can place against and take away from the rear of the baffle whilst music is playing.
The only way I have found to be a tonally acceptable for increasing LF output without introducing an additional upper bass peak is by using soft absorbent side panels like cushions, thick felt layers, carpet or quilting.
Either that or another LF driver as well as soft non reflective and non resonant sides.
Cheers ............ Graham.
Thank you Graham,
So far I was not happy with frames, as they added an upper bass coloration. But then they had no absorbing material, and adding it could change things.
I still think that the sealed bass box may be the most acceptable compromise, as moving OB's further in the room, even when I am listening to the music, is not an option (WAF!)
Regards,
Vix
So far I was not happy with frames, as they added an upper bass coloration. But then they had no absorbing material, and adding it could change things.
I still think that the sealed bass box may be the most acceptable compromise, as moving OB's further in the room, even when I am listening to the music, is not an option (WAF!)
Regards,
Vix
Hi Vix,
I would recomend getting a microphone. It is so much easier to make progress when designing speakers if you can see the frequency and phase response. You probably won't want a flat response in the end but you can work out what is going on so much better.
It really will increase you enjoyment of DIY and you can get the panasonic cartridge quite cheaply this is flat enough for most use. See http://www.johncon.com/john/wm61a/ for an example of how to make a cheap measurement microphone.
Regards,
Andy
I would recomend getting a microphone. It is so much easier to make progress when designing speakers if you can see the frequency and phase response. You probably won't want a flat response in the end but you can work out what is going on so much better.
It really will increase you enjoyment of DIY and you can get the panasonic cartridge quite cheaply this is flat enough for most use. See http://www.johncon.com/john/wm61a/ for an example of how to make a cheap measurement microphone.
Regards,
Andy
Shot in the dark
A friend of mine gave me a broken Marantz amp. PM -68. It was destined for a trash bin, so...I opened it, and while the main amp part was blown and missing, the rest was there..so...hmm..
I tried it, the preamp section and the main transformer were Ok...
So what...
I made a mess in the living room today. Spaghetti....
I decided to use that transformer to quickly assemble Graham's T-bass circuit. (I have tried it before , but with inappropriate transformer, so ther result was not pretty) Now that I could do it properly..why not...
Surprise! With the T-bass circuit in place, I run a first-order passive crossover. Had to pad-down Visaton B200 to bring it in balance.
I found the sound very enjoyable and musical. I have traded-off some efficiency, but since I don't listen loud, it doesn't matter.
So, it seems that I 'll be buying two new transformers and build this circuit ( I have tried only one channel now)...
p.s. Have a look at the cork phase-plugs...
A friend of mine gave me a broken Marantz amp. PM -68. It was destined for a trash bin, so...I opened it, and while the main amp part was blown and missing, the rest was there..so...hmm..
I tried it, the preamp section and the main transformer were Ok...
So what...
I made a mess in the living room today. Spaghetti....
I decided to use that transformer to quickly assemble Graham's T-bass circuit. (I have tried it before , but with inappropriate transformer, so ther result was not pretty) Now that I could do it properly..why not...
Surprise! With the T-bass circuit in place, I run a first-order passive crossover. Had to pad-down Visaton B200 to bring it in balance.
I found the sound very enjoyable and musical. I have traded-off some efficiency, but since I don't listen loud, it doesn't matter.
So, it seems that I 'll be buying two new transformers and build this circuit ( I have tried only one channel now)...
p.s. Have a look at the cork phase-plugs...
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