I tend to think that the real issue is power compression but if you gain 6dB by doubling the number of woofers then I think it really is only the cost factor than stops most of us from using multiple woofers
16R = 83dB
8R=87dB
4R=90dB
Add 6dB to the 16R driver output for the second woofer and you get 89dB ( 2dB more than a single 8R ) and less compression and my amplifier runs cooler
Yes, If you are talking about two 16ohm in paralel
If on the other hand presume 2 8ohm woofers in series, it will be an even call
You gain 3db and loose 3db
Mind you, 2x 10"/16ohm woofers in paralel might be very loud fore a normal mid driver
Theres still the issue with integration
Its hard enough with a 10" but even harder with double 10", if high quality is main priority, tho fore a power speaker it would be better
"Mind you, 2x 10"/16ohm woofers in paralel might be very loud fore a normal mid driver"
If we were talking 10 inch midrange yes it would be, but as woofers with a 5 or 4 inch midrange not so much a problem I think.
In this instance; as it is a follow on to the 2-way speaker thread a passive XO is going to teach people more ( I'm hoping to learn lots ) and 10 inch is a compromise anyway.
There may be a way to use 3 Visaton 8inch(200mm ) woofers, wire 2 8R drivers in parallel and wire the baffle-step as an extra 4R woofer in series with an extra inductor between the parallel pair and the baffle step woofer.
At the moment the Australian price is $AUD 65-, so 6 woofers would be $AUD 390- not exactly cheap but still reasonable.
If we were talking 10 inch midrange yes it would be, but as woofers with a 5 or 4 inch midrange not so much a problem I think.
In this instance; as it is a follow on to the 2-way speaker thread a passive XO is going to teach people more ( I'm hoping to learn lots ) and 10 inch is a compromise anyway.
There may be a way to use 3 Visaton 8inch(200mm ) woofers, wire 2 8R drivers in parallel and wire the baffle-step as an extra 4R woofer in series with an extra inductor between the parallel pair and the baffle step woofer.
At the moment the Australian price is $AUD 65-, so 6 woofers would be $AUD 390- not exactly cheap but still reasonable.
Sorry, but you got it backwards, maybe its my english
I meant 2x 10" might be too loud fore a normal midrange(4"-5"), which would be very unfortunate
In case of multiple 10" you need a mid driver with very good 90db+ sensitivity, or use low SPL woofers
In this case its also common to use double mid drivers, or the bigger 6" mid
"In the old days" it was most common to attenuate a midrange driver with higher sensitivity than the woofers
If you want perfect balance there is no other easy way
It would be based on luck to get it excactly right without
Sure, you may try to calculate from driver specs, but there is no way to know before building and listening, or maybe have very good knowledge about the particular driver used
The excact amount of BSC/attenuation needs to be revised AFTER careful listening in your room
That is if you aim fore best possible inroom balance
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Which was "the" 2-way thread?
This one: http://www.diyaudio.com/forums/multi-way/144025-secret-building-good-2-way.html
Or one of the summa threads?
or something else?
Agreed, a lot can be learned from 2-ways and other simple projects; and they can be quite listenable. My first was a 8½” ML TL, ±1.5 dB 30 Hz up; F3 @ 27 Hz & ~7dB down @ 20 Hz with room gain. Fun.
For BSC, utilise the woofer SPL and crossover point which is one of the advantages of doing a 3-way. A single 10" is a lot easier to work with, still produces bags of bass plus SPL and more economical.
I've never had a SS amp that had issues with 4R loads. That's from Chipamps through to AKSA and Aussie Amp power amps. All these run very cool and easy with lower impedance loads. Chipamps however do need a power supply to suit by running lower rail voltages for lower impedance loads. Even a lot of commercial offerings have a switch for lower impedance loads which alters the rail voltages.... NAD etc.
I've never had a SS amp that had issues with 4R loads. That's from Chipamps through to AKSA and Aussie Amp power amps. All these run very cool and easy with lower impedance loads. Chipamps however do need a power supply to suit by running lower rail voltages for lower impedance loads. Even a lot of commercial offerings have a switch for lower impedance loads which alters the rail voltages.... NAD etc.
I have to admit that baffle step is part of the arcana of speaker building that I have a lot of difficulty with and I'm hoping that I can learn more.
Rabbitz my amps are quite old and do run a little hot and with greater distortion when running low impedance loads, people with newer amps may/will not have that problem; but could you go a little further into why it is easier to design a system around single woofers; please.
Re-reading Vance Dickasons cook-book he does go into some very small detail on integrating woofers with mids and I have seen "Rules of thumb" that say the mid drivers should be approximately half the size of the bass driver.
The "Cook-book" suggests 10 inch woofers with 4inch mids where-as using the 1/2 size rule of thumb would say that 5inch mids are better than 4's with that size woofer.
Personally ; I have never been happy with the sound of small dome mid-range drivers crossed over at above 500Hz, and since I started using the telephone bandwidth (300 - 300 Hz ) for my mid-band my speakers have sounded better.
So for me a 4inch mid is the smallest I would use and because of the problems keeping the cross to a tweeter at a wavelength and therefore needing to keep with a reasonably priced tweeter for this project; 5 inch is the biggest.
Comments???
Rabbitz my amps are quite old and do run a little hot and with greater distortion when running low impedance loads, people with newer amps may/will not have that problem; but could you go a little further into why it is easier to design a system around single woofers; please.
Re-reading Vance Dickasons cook-book he does go into some very small detail on integrating woofers with mids and I have seen "Rules of thumb" that say the mid drivers should be approximately half the size of the bass driver.
The "Cook-book" suggests 10 inch woofers with 4inch mids where-as using the 1/2 size rule of thumb would say that 5inch mids are better than 4's with that size woofer.
Personally ; I have never been happy with the sound of small dome mid-range drivers crossed over at above 500Hz, and since I started using the telephone bandwidth (300 - 300 Hz ) for my mid-band my speakers have sounded better.
So for me a 4inch mid is the smallest I would use and because of the problems keeping the cross to a tweeter at a wavelength and therefore needing to keep with a reasonably priced tweeter for this project; 5 inch is the biggest.
Comments???
Area or diameter ?
That's why I'm asking . And regarding :
How many LF drivers are you going to mate with the mid ?
"Area or diameter ?"
Well I had assumed diameter
"How many LF drivers are you going to mate with the mid ?"
I would say that is the whole reason for the thread, so these design issues can be talked through and a reasonable set of design criteria could be amalgamated in one place.
I have a set of 10 inch woofers from Jaycar I was thinking of using in my set-up; mating to a pair of P-13s.
I have a copy of the Weems book and in it he has a design for a 3-way using the P-13 as the mid, but that uses a discontinued Peerless 8 inch woofer and crossed quite high, the bandpass in that design is 600 -> 2700 using the Vifa D27 45-06.
Well I had assumed diameter
"How many LF drivers are you going to mate with the mid ?"
I would say that is the whole reason for the thread, so these design issues can be talked through and a reasonable set of design criteria could be amalgamated in one place.
I have a set of 10 inch woofers from Jaycar I was thinking of using in my set-up; mating to a pair of P-13s.
I have a copy of the Weems book and in it he has a design for a 3-way using the P-13 as the mid, but that uses a discontinued Peerless 8 inch woofer and crossed quite high, the bandpass in that design is 600 -> 2700 using the Vifa D27 45-06.
Funny . The " rule " as I intended was to consider the area -more or less or about -
But this " more or less " would fail in the future calculations half a magnitude if the diameter was taken in consideration .
But this " more or less " would fail in the future calculations half a magnitude if the diameter was taken in consideration .
Integration
Mentioned several times
Some will calculate wavelength and may say that 300hz is ok
But you have to consider that its the woofers stopband that determines how well it integrates with the top
Consider that you have one woofer with little distance to midrange, and another with greater distance
Its bound to cause phase issues
Ideally they should at least be physically phase allignet
Also, there seem to be some issue with say two woofers not exactly alike
Its still debated whether two equal drivers should be in a mutual chamber or if they should have each their own
I use two 8", and had loud muddy and blurred bass fore a long time
Very anoying
I have solved it though, but it was tricky and took some serious work
The first step was to mount two exstra magnets, but only on one, the bottom woofer
Strange thing to do, but it really works
But didnt really solve the problem
From there on it was solely xo work, lots of work
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Well I have always tried to cross really low as I had been told the integration was easier that way, that and keeping the drivers close together, although i was under the impression that the wavelength at 300 Hz and below meant woofer to mid distance was less critical.
When bi-amping I tend to cross about 120- 150 and that works for me
When bi-amping I tend to cross about 120- 150 and that works for me
For baffle step a good starting point is 115/Baffle Width in metres, so for a 350mm wide baffle we get 328Hz so 300Hz or lower is a good place to crossover for 1st order xo. You can shape the roll off above that point by an zobel and I tend to use oversized zobels in this location to force the woofer down quickly after the xo point (large cap in the zobel acts like a psuedo 2nd order??). For it to work effectively the woofer needs a higher SPL than the mid and the SPL depends on how much BSC you need. In my environment I only need 2-4dB. The other thing to consider is the woofer usually has to be in it's operating range at least 2 or more octaves past the crossover point.
Ah... I see about the amp now. I had a Sansui AU-717 which went into protection mode on low impedance loads but a low powered NAD 7220PE sailed through it. I think a lot of the older amps were part of the specification race for higher power ratings and to do that they ramped up the rail voltages which in turn reduced low impedance capabilities.
A single woofer system has less variables which helps in crossover design, tends to give better cohesion (closer to point source even though the wavelength of the xo point is much larger than the distance to the mid driver?) and can be built smaller. I tend to keep my woofers reasonably low in the enclosure to help with room loading and put the mids it's producing off axis as I want most of the mids coming from the mid driver which is just below ear level. I'm of the school if you need more bass, SPL, extension etc, use a larger driver as there's no subtitute for surface area IMO. Multiple woofers can give less distortion, less travel but a large woofer doesn't have to travel as far when it has a large Sd. I'm no expert on multiple drivers but getting 2 drivers to share the work equally can be a problem plus it raises the woofers higher if used in a TMWW. This is of course a personal choice only.
Size of the mid is related to the crossover point and it's operating range. I have a personal preference for a larger than 4" mid as you tend to get a fuller sound with more body and weight and would use a 5" at a minimum. I believe this is a major draw back on dome mids (unless the woofer is crossed over very high). The speaker in the pic was built first with the PL11MH mid (left pic) and then with the XG18 as a mid (right pic).... no prizes for which one sounded better, had more body and better power handling.
Attachments
I tend to agree as I want my mids coming from 1 driver and the woofer doing bass only so crossover below 150Hz. Depends on the capabilities and operating range of the mid and generally requires a 6" mid. A 5" should be OK for 200Hz. The thing to remember that most mids used these days are actually mid woofers so can be pushed lower than a dedicated mid driver.
At 300Hz you can have the woofer over 1m from the mid in theory.
It is. In my existing system Ì`m using a slightly modified Dynaudio D-52(that used to be)AF. Removing the oil and adding a beer-can sized rear chamber opened it up a bit.
Since the Dynaudios are unawayable these days I`ve looked high and low for a good replacement. Tryed out some, but no good ones so far.
This cheap 3" looks good from the FR:
Parts-Express.com: Tang Band 75-1558SE 3" Textile Dome Midrange | Tang Band 75-1558SE tang band tb speakers dome midrange silk dome fabric dome soft dome
..and this one might fit right in:
DM-75TB
I`ve bought me another set of D-52`s as a reference and eventually backups in case no others makes me satisfyed😕
I agree, normally a smaller driver will give you more detail and a larger driver, more body. The optimum is somewhere in between, I would say between 5" and 6.5" would do well.
Well, I tend to try cross woofer as high as possible
These new ScanSpeak Discovery looks great fore affordable design
Just picked those and Im NOT suggesting they would be best
http://www.scan-speak.dk/datasheet/pdf/r2604-832000.pdf
http://www.scan-speak.dk/datasheet/pdf/10f-8424g00.pdf
http://www.scan-speak.dk/datasheet/pdf/22w_4534g00.pdf
These new ScanSpeak Discovery looks great fore affordable design
Just picked those and Im NOT suggesting they would be best
http://www.scan-speak.dk/datasheet/pdf/r2604-832000.pdf
http://www.scan-speak.dk/datasheet/pdf/10f-8424g00.pdf
http://www.scan-speak.dk/datasheet/pdf/22w_4534g00.pdf
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In Tysen (XO @ 333 HZ) we started with the woofer at the floor (say 25" from mid-tweeter) but found that things worked much better when the woofer was as close as possible.
dave