I can think of three disadvantages:
1. The rear of the cones are now in a more strongly coloured acoustic environment, the sound of which is transmitted through the cone material and thus added (unwanted) to the signal. The avoidance of this is one of the primary advantages of open baffle.
2. You lose the advantage of dipolar bass in that with dipolar there is a degree of cancellation of net bass energy in the room as a whole, and as a result less bass bleed to other rooms sharing the same general acoustic environment.
3. You sacrifice the advantage of being to aim the nulls around to your advantage, particularly as regards first reflections from side walls.
...and two advantages:
1. Easier to get deep bass extension and power
2. potentially less physically intrusive into the listening area
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New project
Hi John,
Thanks for sharing these designs.
I'm heading over to the states to visit friends, so an opportunity to order from parts express For a new ob project.
Is either the ultra or Manzanita Bi amp compatible?
I have a 5 watt set I use for mids and highs and was going to buy something like a tripath or class d for the lower frequencies, Any advice?
Many thanks
Ian
Hi John,
Thanks for sharing these designs.
I'm heading over to the states to visit friends, so an opportunity to order from parts express For a new ob project.
Is either the ultra or Manzanita Bi amp compatible?
I have a 5 watt set I use for mids and highs and was going to buy something like a tripath or class d for the lower frequencies, Any advice?
Many thanks
Ian
Webby
Thank you for your interest in the Manzanita - Ultra designs.
Both designs take advantage of simple Passive crossover methods that, I have been told, can be difficult to duplicate in a bi-amp situation. With enough time and effort, I am pretty sure it could be done, especially by someone with deep experience with both passive and active crossover design. If I were to undertake an active design alternative, and keeping in mind that active designs are not my strong suit, I would do the passive first as a bench mark and adjust it to personal realities. Then I would work out the active alternative. I am fairly certain there are those with a lot of active experience who can reach a viable solution with out doing a passive first. An active on the Manzanita LF would have the advantage of not creating the bump in the 48- 56 Hz region caused by the large passive inductor. The Vifa's rising response is easy to correct in both designs. The Ultra baffle dimensions and the higher Q of the 15 is pretty much bass bump free. Anyway, I could go on for ever about how the passive designs actually do there thing. I don't like encouraging fellow DIY'ers spending money on any of my projects unless I feel confident I have provided enough base info for them to succeed. I think you understand what I am say here. Good luck if you choose to move forward with an active version of either design!!
Thank you for your interest in the Manzanita - Ultra designs.
Both designs take advantage of simple Passive crossover methods that, I have been told, can be difficult to duplicate in a bi-amp situation. With enough time and effort, I am pretty sure it could be done, especially by someone with deep experience with both passive and active crossover design. If I were to undertake an active design alternative, and keeping in mind that active designs are not my strong suit, I would do the passive first as a bench mark and adjust it to personal realities. Then I would work out the active alternative. I am fairly certain there are those with a lot of active experience who can reach a viable solution with out doing a passive first. An active on the Manzanita LF would have the advantage of not creating the bump in the 48- 56 Hz region caused by the large passive inductor. The Vifa's rising response is easy to correct in both designs. The Ultra baffle dimensions and the higher Q of the 15 is pretty much bass bump free. Anyway, I could go on for ever about how the passive designs actually do there thing. I don't like encouraging fellow DIY'ers spending money on any of my projects unless I feel confident I have provided enough base info for them to succeed. I think you understand what I am say here. Good luck if you choose to move forward with an active version of either design!!
Webby
Not sure if you are asking about bi-amp with the passive filter, or an active crossover. If active, then John has answered above. If passive with 2 amps, then you should be OK. Just wire the crossover so that you can attach one amp to the woofer section, the other to the Vifa.
Now that said, with a low power SET amp you would want to remove as much attenuation on the Vifa as possible. You would do the level matching with the amp volume controls. That will give your SET more headroom, and it will need it. Of course once you do that, you'll have to change the other parts value too - because they won't see the same impedance.
I agree with John, build the passive single amp version first, get it adjusted to your room and your taste. After that a passive bi-amp version should not be hard to implement.
Not sure if you are asking about bi-amp with the passive filter, or an active crossover. If active, then John has answered above. If passive with 2 amps, then you should be OK. Just wire the crossover so that you can attach one amp to the woofer section, the other to the Vifa.
Now that said, with a low power SET amp you would want to remove as much attenuation on the Vifa as possible. You would do the level matching with the amp volume controls. That will give your SET more headroom, and it will need it. Of course once you do that, you'll have to change the other parts value too - because they won't see the same impedance.
I agree with John, build the passive single amp version first, get it adjusted to your room and your taste. After that a passive bi-amp version should not be hard to implement.
Thanks John and pano for the replies.
I was asking about bi-amp with the passive filter, Making use of my SET amp for the highs and adding another to power the woofer.
Do you recommend a class D, tripath or other?
How would you describe the soundstage with these designs, width and depth etc
I am currently using a 15in H frame powered by two sub amps
and open baffle 8 In fullrage powered by my SET.
Gone from wide baffle, narrow baffle, now H frame.
To be honest, I'm a little lost and wanted a fully sorted design like the ultra to get back on track.
Many thanks
Ian
I was asking about bi-amp with the passive filter, Making use of my SET amp for the highs and adding another to power the woofer.
Do you recommend a class D, tripath or other?
How would you describe the soundstage with these designs, width and depth etc
I am currently using a 15in H frame powered by two sub amps
and open baffle 8 In fullrage powered by my SET.
Gone from wide baffle, narrow baffle, now H frame.
To be honest, I'm a little lost and wanted a fully sorted design like the ultra to get back on track.
Many thanks
Ian
Ian, if you would like to contact me through Decibel Dungeon, I may be able to help you.
Should be the opposite, since the bass is dipolar.
Maybe they will invite themselves in!
Apartment suitability
Russell has it right. As long as you can get the speaker 30" or more away from the rear walls, it will sound balanced. And most of the bass energy will stay in the room. Very limited standing waves which is what gets one in trouble with close neighbors. We have all experienced the BOOM BOOM effect of a box speaker playing in .... well a larger box!
Russell has it right. As long as you can get the speaker 30" or more away from the rear walls, it will sound balanced. And most of the bass energy will stay in the room. Very limited standing waves which is what gets one in trouble with close neighbors. We have all experienced the BOOM BOOM effect of a box speaker playing in .... well a larger box!
Hello Tyee..
John here.... I need to re-visit the most recent configuration using the D3806 and get back to you. I think right at the end of that format I added a trap to flatten out the modest rising response of the D3806... I don't think it was ever posted as the design transitioned to the Vifa 3.5" full range as a concession to the substantial rising cost of the D3806 at that time.
Best
John
John here.... I need to re-visit the most recent configuration using the D3806 and get back to you. I think right at the end of that format I added a trap to flatten out the modest rising response of the D3806... I don't think it was ever posted as the design transitioned to the Vifa 3.5" full range as a concession to the substantial rising cost of the D3806 at that time.
Best
John
I think I found the last description on page 28 -
http://www.diyaudio.com/forums/multi-way/110583-fast-fun-inexpensive-ob-project-28.html#post2247245
3 posts down from there is the final schematic that "teamacc" drew from John's description I believe. Please confirm.
http://www.diyaudio.com/forums/multi-way/110583-fast-fun-inexpensive-ob-project-28.html#post2247245
3 posts down from there is the final schematic that "teamacc" drew from John's description I believe. Please confirm.