Re: again costs passive versus active
I just followed the link in Your post. Great thread!
Chops, this is what Your test bed for Your crossover will look like, only much bigger as Your`s is a 4-way and will cross much lower:
www.htguide.com/forum/attachment.php4?attachmentid=10320&stc=1
I´ll leave it to You to imagine what such a pile of crossover parts will cost You.
I just followed the link in Your post. Great thread!
Chops, this is what Your test bed for Your crossover will look like, only much bigger as Your`s is a 4-way and will cross much lower:
www.htguide.com/forum/attachment.php4?attachmentid=10320&stc=1
I´ll leave it to You to imagine what such a pile of crossover parts will cost You.
Remind me not to respond to anymore of your posts...
I`ve seen it coming...
cocolino said:
As "Nanook" mentioned already, good inductors for low frequency Xovers are expensive and You`d need more than those You finally use in the crossover. A passive 4-way is complex, You need a big parts box to play with.
I`d really advise to reconsider this.
Getting a passive 4-way crossover right isn`t exactly a trivial thing.
I`m convinced that in this case doing the woofer part active, will simplify the contruction of the crossover considerably.
Altough I´m now messing about 25 years with DIY speakers and I have all the equipment one can think of and that could be handy, I wouldn`t want to do a 4-way passive anymore.
I don`t say it can`t be done and the last thing I`d want is to spoil Your fun but my gut feeling tells me that You`ll probably run in much more trouble that You can think of in the moment.
You`ve got quite a big project there. I`d suggest not to hurry too much (very near future project), let sink things in a bit more and collect a few more opinions meanwhile.
Who is talking about buying?
I thought this site is about DIY
Seriously, even if You can`t or don`t want to DIY, for making only the woofer part active all You need is one stereo amp more. The amp for the woofer needn`t to be of the best quality, more power is better in this case.
The active crossover could be a more of a problem though. I don`t know what`s the cost of commercial ones as I never waste a thought about this because I make mine myself.
OTOH an active crossover with op-amps is easy to built. You don`t have to understand much of electronic crossover theory, there are spreadsheets for this which makes things quite easy.
If You want to get Your feets wet, here only one example to begin with (the two links are about the same crossover):
http://www.diyaudio.com/forums/showthread.php?threadid=74420
http://mysite.verizon.net/vze3xvxs/audio/id20.html
It might work but I doubt it. I´d imagine You`d need LOTS of padding to absorb something like 250Hz waves.
Here only two examples:
http://www.t-linespeakers.org/tech/bafflestep/index.html
http://sound.westhost.com/bafflestep.htm
The net is full on this topic, just google for "baffle-step" and You`ll find plenty to read.
Alright, how about if I scrap that entire projuct and do this instead...
I could go with a pair of Dayton RS270S-8 10" woofers per enclosure, cross them over to an Usher 9845 2" dome mid, then finish it off with a Vifa XT25TG30-04 1" dual concentric dome tweeter.
This would be a classic 3-way design and should be easier to do.
The only problem I see is the efficiency differences between these drivers. With the Dayton 10's (90.5dB each) wired in parallel, they would be roughly 94dB. The Usher dome-mid is 92dB and the Vifa tweeter is 91dB.
Is it possible to insert an L-Pad into the woofer circuit like you would a tweeter? And the L-Pads I'm referring to are the two resistors kind, not those cheap potentiometer kind.
Also, what xover points would be good for these drivers, mainly from the woofers to the dome-mid?
The Fs of the Usher mid is 410Hz. 1.5 octaves above that is about 1025Hz, correct? If so, that would be pushing the Dayton woofers near their limits of 1500Hz. Of could I get this down lower like 750 - 800Hz if I use a 4th order?
The Usher reaches up to 8kHz, so I could cross over to the tweeter around 4 - 5kHz or so, I guess.
Please tell me your thoughts on this combo if you don't mind.
BTW, thanks for the links!
I don`t mind at all ... if You don`t mind ....if I tell You something what You possibly might not like to hear.
More later, daylight is coming and I have to do what I should have done already a few hours ago
P.S.
Not that I´m unsafe about what I have to say but I´d feel more comfortable if somebody else could also throw their two cents in meanwhile.
If I were You, I wouldn`t rely much on one opinion only.
chops said:
How do you figure it doesn't cost more than a passive network?!
I would have to buy more amps and another electronic crossover. I don't know about you, but that would cost a heck of a lot more than going passive.
Hi chops,
I'd say that a passive network also costs a lot more if you want to achieve the same level of sound quality. In my limited experience, downgrading to passive sounded about the same as downgrading from a dedicated CD player + class-AB power amp to a cheap ghetto-blaster source (ignoring certain limitations such as theoretical max power and whatnot.) So the difference is quite noticeable. Besides, you said you had a plenty of amps lying around.
Re: baffle step correction
Why not just use the extra 6dB of sensitivity of the 4 woofers to your advantage?
And isn't 7" a bit big for a low-mid if the woofers are 6.5" and the upper mid is 2"? In general, some of your driver choices seem a bit counter-intuitive... But hey, that's just my opinion. Personally, I'd stick to a 3-way design (e.g.: 10", 4.5", 1" - and in fact I've been planning such a design on my website - the last update was a few weeks ago though).
Or, if I'm going to all that trouble of making a 4-way design, I might as well stretch the range a little, and use say: 2 x 12" subs per side, 8" low-mids, 4~3" high mids, and 1" or 3/4" super-tweeters.
Cheers,
CeramicMan said:
I forgot to mention earlier... Those amps I was talking about are the ones in my theater system, not unused amps just sitting around.
I was just saying that if I had to, I could pull them (along with the Rane xover) from the theater for a little bit to do tuning on the project speakers.
chops said:
Alright, how about if I scrap that entire projuct and do this instead...
I could go with a pair of Dayton RS270S-8 10" woofers per enclosure, cross them over to an Usher 9845 2" dome mid, then finish it off with a Vifa XT25TG30-04 1" dual concentric dome tweeter.
This would be a classic 3-way design and should be easier to do.
The only problem I see is the efficiency differences between these drivers. With the Dayton 10's (90.5dB each) wired in parallel, they would be roughly 94dB. The Usher dome-mid is 92dB and the Vifa tweeter is 91dB.
Is it possible to insert an L-Pad into the woofer circuit like you would a tweeter? And the L-Pads I'm referring to are the two resistors kind, not those cheap potentiometer kind.
Also, what xover points would be good for these drivers, mainly from the woofers to the dome-mid?
The Fs of the Usher mid is 410Hz. 1.5 octaves above that is about 1025Hz, correct? If so, that would be pushing the Dayton woofers near their limits of 1500Hz. Of could I get this down lower like 750 - 800Hz if I use a 4th order?
The Usher reaches up to 8kHz, so I could cross over to the tweeter around 4 - 5kHz or so, I guess.
Please tell me your thoughts on this combo if you don't mind.
BTW, thanks for the links!
After some more thought, I think I'm going to drop the dome-mid idea from the project. As much as I'd love to try one out, I just don't think they can cover a wide enough bandwidth for this project. The lowest I could cross one of them over is about 700Hz, and I don't want to really cross over that high.
So this is what I'm thinking... Since the midrange frequencies are the most important and is usually best to stay within one driver, I want/need a driver that can span from about 400Hz all the way up to 4000Hz or so. With that in mind, I'm seriously thinking about going with a pair of Vifa P13WH-00 5" woofers per channel. Since these little Vifa's are known for having very smooth responses and are capable of 60 - 5000Hz, these would easily cover the 400 - 4000Hz range, and I could probably even cross them lower, say 135Hz or so.
Any thoughts or suggestions on this combo along with the Dayton RS270S-8 10" woofers and Vifa XT25TG30-04 1" dual concentric dome tweeters?
Re: Re: chops: thanks for the info!
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=267-766
low end pass pretty much taken care of, and WAY cheaper than what you will have to pay for inductors
chops said:
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=267-766
low end pass pretty much taken care of, and WAY cheaper than what you will have to pay for inductors
chops said:
Now you are getting closer to sensible. The Vifa P13 should be crossed in at around 200-250, ie below the main vocal range.... (assuming the 10" doesn't have any big problems before about 1kHz).
BUT, unless you really know what you are doing, I would avoid the XT25, really nice tweeter , but can be a problem if you get the x-o wrong. If you use 2 of the Vifa P13 a side, I would assume you would be using an MTM+W config, which means you need to cross to the tweeter at between 2k and 2.5k. I would suggest one of the Seas 27Txxx tweeters instead for this purpose. Solid and very good sounding.
Going 3-way instead of 4 way gets rid of the problem of really massive inductors (with associated cost!) for the low x-o point, and means that you can generally get away without having to consider active x-os and extra amps. Good choice there.
(mind you, the inductors, even in a 3-way, are not going to be puppies !!)
Little late with my reply, but better late than never.
I`m glad You changed Your mind.
This saved me to express and explain my dislikes against Your previous project idea and dome midrange drivers (particular in a 3-way system) and their limited use of application.
I think You`re on a very good track now with Your latest 3-way idea.
Exactly what I`m thinking.
Last but not least such a classical 3-way application is much more feasible in regard to the enormous challenge of a (passive) 4-way Xover.
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