Bauvorslag VOX200 mit active weiche

[Roybo]

Hello,
I'm sorry to use English, but my German is much worse.
My question is more general than building the VOX 200, but I will use it as an example: When I would build the VOX200, I would want to tri-wire it, using an active crossover and 3 monoblocks (amps).

1. Would it suffice to just make the cabinet as proposed in the "Bauvorslag", to leave the passive crossover out and instead build an active crossover (LR24) with the same crossoverfrequencies?
2. More general: When designing an 2- or more-way loudspeaker, can I just suffice with engineering a cabinet for the best bass-reproduction, then find mid-speakers and/or tweeters which complement this box in both pressurelevel and frequencyresponse ?

FYI:
-- I know that the best speaker has a flat frequencyresponse
-- I know the Linkwitz-theory on active filters
-- I do not (want to) know (a lot) about measuring, I hope to find the right box without it.
-- I know how to engineer cabinets to reproduce the best possible bass (in theory, that is)
-- And much more, but that is irrelevant

Thanks in advance!

[CheGuevara]

Hello!
I think a better solution, with filters optimized for that special purpose, would be the "Jeani", a active 3-way-speaker developed by klaus lorenz (also a member of this forum). http://www.lautsprechershop.de/hifi/jeani.htm

its design is very similar to the Vox200, also using two Ti100 in the midrange. but I guess it will achieve a better result than simply kombining standard active filters with some (very good) speakers.

edit: referring to your general questions:
A standard LR24 can only achieve a perfect frequency response of all 3 ways added, when each speaker has a perfect frequency response at all frequencies it is used and in the cabinet it is mounted! even if you find speakers which fullfill the first aspect, the baffle always leads to the "baffle step" which cannot be compensated with a LR24 filter!

Che

[UweG]

It cannot be recommended to replace a good working passive crossover network by an active one that uses only linkwitz filters. The result ist surely worse than before. The main reasons are:
- Linkwitz filters require same phase behavior of both speakers at and around the crossover frequency. In practice this is normally not the case.
- Nearly no speaker has a flat frequency response if mounted on your specific baffle, even if it is flat on an infinite baffle.

The VISATON speaker kits are optimized to produce a flat frequency response in the free field. To achive this with an active crossover network you have to create special filters for your specific box.

[Roybo]

re:

Thank you UweG and Che,
I will be gone abroad till te next weekend, then I will respond on your answers, because you leave me with even more questions . I hope: till next weekend!

[Roybo]

still some questions

Oke,

I think a better solution, with filters optimized for that special purpose, would be the "Jeani", a active 3-way-speaker developed by klaus lorenz (also a member of this forum).

I have to make clear that using the VOX is just a theoretical option. I'm looking for ways to design a good active loudspeaker, preferably without having to use expensive means to measure the perfomance. Otherwise, the Jeanni would be a nice suggestion though.

Some questions:
1.

- Linkwitz filters require same phase behavior of both speakers at and around the crossover frequency. In practice this is normally not the case.

I think I understand what you mean. Is there a way to predict the difference in fase at and around the crossoverfrequency? If so, isn't it so that you can correct this by placing one unit deeper in the baffle than the other? Or is there a 'correcting electronic scheme' that can level the fase-difference? (please, insert a link or send me such a scheme if you have one)
2.

The VISATON speaker kits are optimized to produce a flat frequency response in the free field. To achive this with an active crossover network you have to create special filters for your specific box.

Would those be 'notch'-filters? Is there a way to predict the frequencies for which to build those?
3. If it is possible to use computerprograms to calculate passive crossovers, (why) isn't it possible to calculate more accurate active crossovers? Do you know a program that can?

[CheGuevara]

Re: still some questions

Original geschrieben von Roybo

1.
I think I understand what you mean. Is there a way to predict the difference in fase at and around the crossoverfrequency? If so, isn't it so that you can correct this by placing one unit deeper in the baffle than the other? Or is there a 'correcting electronic scheme' that can level the fase-difference? (please, insert a link or send me such a scheme if you have one)

both ways can lead to a solution to adapt the phase around the XO-frequency: either a geometrical delay or an electric delay with an all-pass filter.
the problem is to get reliable measurements of the phase-response of each speaker.

Original geschrieben von Roybo
2.
Would those be 'notch'-filters? Is there a way to predict the frequencies for which to build those?

notch-filters do afaik boost (not very recommended) or reduce a certain frequency, this cannot include all efffects necessary for a flat freq.-response.

Original geschrieben von Roybo
3. If it is possible to use computerprograms to calculate passive crossovers, (why) isn't it possible to calculate more accurate active crossovers? Do you know a program that can?

boxsim (click the link in uwe's signature to download the simulation can also simulate active filters 6/12/18/24dB/oct with the parameters Q and f.

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