A genuine priceless treasure that. I got my first home-knitted sweater just a few years back, invaluable to me.
Here's the issue, the conundrum that faces owners of floor-standing speakers everywhere.
Here's a pair of Toshiba floor-standing cabinets (22) litres. It has been suggested that the volume be reduced by 8 litres for efficiency. The speakers sound okay but could do with a little more oomph. How about I add a couple of small subs to the system for bass reinforcement?
Akshally . . . I don't need to build new cabs because I know where there's 8 litres of real estate going spare. But if I'm going to do that I don't need the bass extension on the woofers. I can seal them in 6 litres leaving 14 for the sub driver.
Which all leads to the question that can't be answered using generally available formulae. Why seal the woofer? Why can't the woofer and the sub share the same air-space?
Here's a pair of Toshiba floor-standing cabinets (22) litres. It has been suggested that the volume be reduced by 8 litres for efficiency. The speakers sound okay but could do with a little more oomph. How about I add a couple of small subs to the system for bass reinforcement?
Akshally . . . I don't need to build new cabs because I know where there's 8 litres of real estate going spare. But if I'm going to do that I don't need the bass extension on the woofers. I can seal them in 6 litres leaving 14 for the sub driver.
Which all leads to the question that can't be answered using generally available formulae. Why seal the woofer? Why can't the woofer and the sub share the same air-space?
Attachments
Because putting in a more powerful woofer with more xmax will translate to: you're forcefully pushing the membrane of the weaker midrange driver...
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The good thing will be that you can put in a cup over the now midrange since it does not need that much space to go down to, say, 250hz. = more space for the new woofer.
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How can you call that a floorstander? Should be more like a short-shelfstander or something. Unless you sit on the floor, in which case it is quite suitable as a floorstander.
Edit:
The good thing will be that you can put in a cup over the now midrange since it does not need that much space to go down to, say, 250hz. = more space for the new woofer.
Edit2:
How can you call that a floorstander? Should be more like a short-shelfstander or something. Unless you sit on the floor, in which case it is quite suitable as a floorstander.
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Somebody kindly sent me an article (which I cannot find) on different drivers sharing the same airspace. Long story short: Years ago I had a mobile disco with 2 x 12" Fane speakers. When a Fane driver blew I replaced it with a cheap alternative. The cabinet sounded so much better that I installed another in the other cabinet. The cheap driver had a much lower resonant frequency than the original driver.
The article intimated that the relationship drivers was extremely complicated but not necessarily negative.
In your conventional thinking (x-over @ 250Hz) the woofer has occasion to behave as pseudo passive radiator to the sub. But in a more literal interpretation of the woofer / sub-woofer relationship it becomes more interesting. Woofer 55Hz, Sub 30Hz
No musical note is a sine wave.
For example: a low note struck on a bass guitar. Both the sub-woofer and woofer are interested, moving forward. Under load, the woofer is unable to act as a passive radiator, it behaves as cabinet wall. Subsequently, the excess air pressure is sent to the port.
It's way more complicated than that but, hey, the basics.
Now let’s throw another kink into your venture.
Althou they will be fighting it, that box is going to perform like an ML-TL and not a reflex. A reflex modeler will not do a good job of simming them.
Given that, if you are intending them to be BR< putting some volume at the bottom to decrease the internal height would be a good thing.
dave
PS: tose boxes really need braces. I have some of those kind of Audax/clone tweeters in my giveaway pile.
It can be done, but is very tricky and not advised.
Sims suggest about 7 litres stuffed if you want ot use the Peerless as a midTweeter. Natural 2nd order butterworth roll-off could be used with a complementary LP on the woofers. 2 palte amps with 2nd order XOs would sugegst themselves if approached like this.
XO would (practically) need to be considerably higher if you wanted to do a passive XO.
dave
dave
It seems your thinking is limited by the flexibility of your simulation software. Let's not use the Peerless as a mid-tweeter and we use it as the bass-mid for which it was designed.
As suggest by the elusive article: take the TS parameters of the Peerless woofer.
Resonant frequencyfS42
Hz Electrical Q QES 0.50
Mechanical Q QMS 3.2
Total Q factor QTS 0.4
Suspension equivalent air volumeVAS24.2litres
And the TS parameters of the sub driver:
Resonant frequencyfS25Hz Electrical Q QES 0.22
Mechanical Q QMS 1.55
Total Q factor QTS 0.20
Suspension equivalent air volumeVAS68.6litres
Add the relevant factors together and divide by 2. Now tell your modelling software your cabinet contains two drivers of the new specification.
I do not wish to be rude to you, and whatever deity is behind creation knows I've played my share of smart *** comments in my youth. I try to be better, but it's very hard to correct ones own flaws
Please take this to heart, or you may eventually find that people simply choose to avoid answering you.
You're asking for advice and how to figure stuff out, how it works etc, but it seems to me like you ignore everything anyway.
There's no point asking for help if you continuously decide to blindly ignore the knowledge freely offered to aid you.
Even the most basic stuff seems unable to stick, and you reply in a defensive manner, throwing a few smart words about that are clearly very misplaced.
If you don't agree with any of the answers you're getting, perhaps try asking questions that you actually want answers for.
Huh.
The modeling software needs know nothing about 2 boxes. Only the user.
I am quite satisfied with the veracity of my modeler, it has helped me design literally hundreds of successful speaker boxes. I do not doubt its suggestions.
The modeler is just a tool. The user has to know what they are doing.
dave
Yeah, his overall ignorance and worst, apparently proud of it overlaid with mass quantities of condescension makes me sad that he's apparently never learned [or at least 'taken to heart'] the dictum of 'best to keep one's words soft n' sweet in case one needs to eat them'.
I've said before and I'll say it again: I've no interest in receiving advice from people who are lacking in critical thinking.
WinIsd software for modelling speaker CONSTRUCTION projects. It is not a tuning tool.
I have a perfectly serviceable 22 litre cabinet. Only a moron would build a new cabinet because the modelling software does not allow the user to manually change the length of the vent.
If I am in possession of two bass drivers of differing specs I am not going change the designation of one driver because the software cannot facilitate that particular scenario.
I have a copy of WinIsd. I wouldn't be asking the question if it had the answers.
WinIsd software for modelling speaker CONSTRUCTION projects. It is not a tuning tool.
I have a perfectly serviceable 22 litre cabinet. Only a moron would build a new cabinet because the modelling software does not allow the user to manually change the length of the vent.
If I am in possession of two bass drivers of differing specs I am not going change the designation of one driver because the software cannot facilitate that particular scenario.
I have a copy of WinIsd. I wouldn't be asking the question if it had the answers.
Hi, slap in the subwoofer and see what you get, if that is the cabinet and those are the drivers. It would be better to modify the cabinet, as suggested. Seal the current woofer into its own compartment and use it as mid. Add the sub for the remaining space and you have a three way system. The response is what you get, unless you build new cabinet or change the drivers. You can use the winISD to predict response of such modification to see if it is worth it*. Might be easier to build the subs into separate boxes though, less crossover work (since the original speaker is not modified) and you can reuse or sell either the speakers or subs separately at later date.
*WinISD doesn't let to change the vent length (area can be changed) but you can change the cabinet size, vent area and tuning frequency, which automatically changes the vent length to match so it can be used kind of backwards in your situation. Hope it helps.
*WinISD doesn't let to change the vent length (area can be changed) but you can change the cabinet size, vent area and tuning frequency, which automatically changes the vent length to match so it can be used kind of backwards in your situation. Hope it helps.
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You want us to tell you the new port frequency, ok. You don't want to change your box volume, you said that before.. ok.
You want us to tell you it will be good? Another day, perhaps.
You best know the limits if you have experience.. and you have experience when you know how to do it without the simulator. So now you trust yourself to use the simulator.planet10 said:
You seem to be cutting off your nose to spite your face here...
Put your driver specs into winISD.
Tell winISD you have a 22 Litre box
Go to the vents tab and set the vent diameter to the one in your box.
Look at the vent length.
If you want to model a longer vent, go to box tab and lower the tuning frequency a bit at a time until the vent length is the length you want to model.
If you want to model a shorter vent raise the tuning frequency in the box tab until the vent length matches what you want it to measure.
A bit of a faff, but you'll get there within a couple of minutes, even a moron could do it
Rob.
Pass DIY Addict
Joined 2000
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Like others, I am inclined to suggest a pinch of humility here. You have some very experienced and very successful speaker designers and builders trying to help you. You appear to be working hard to prevent them from doing so. The people that have responded thus far have likely forgotten a greater volume of knowledge on this topic than others will ever learn. Slow down and take advantage of the expertise that is here.
Sure, simulation tools are not the be-all and end-all. Many designers use sims as a starting point and then tweak in order to achieve specific goals. Simulation tools are great platforms for experimenting and learning - especially when you are relatively new to a specific domain.
I applaud your efforts to modify/reuse these drivers and boxes. I think too many people are too quick to throw away items that can be repaired or reused. At the same time, it is my experience that efforts to refit inexpensive and mass-produced speakers rarely result in satisfactory outcomes. There are often too many places where corners have been cut: less than adequate - or mostly missing - crossovers (because good crossover design is an art form and good crossover components are expensive), cabinet materials that are too thin, poorly joined, and have no bracing (because it costs more to ship well-designed, heavy cabinets), drivers that are barely up to the task of producing sound without making people cringe (because they cost $6 when purchased in bulk)... There may be something worth salvaging here for minimal investment. I'd be surprised, though. If you are looking for better-quality sound reproduction, you might be better off passing these along to someone who will appreciate them and building something more to your liking.
Sure, simulation tools are not the be-all and end-all. Many designers use sims as a starting point and then tweak in order to achieve specific goals. Simulation tools are great platforms for experimenting and learning - especially when you are relatively new to a specific domain.
I applaud your efforts to modify/reuse these drivers and boxes. I think too many people are too quick to throw away items that can be repaired or reused. At the same time, it is my experience that efforts to refit inexpensive and mass-produced speakers rarely result in satisfactory outcomes. There are often too many places where corners have been cut: less than adequate - or mostly missing - crossovers (because good crossover design is an art form and good crossover components are expensive), cabinet materials that are too thin, poorly joined, and have no bracing (because it costs more to ship well-designed, heavy cabinets), drivers that are barely up to the task of producing sound without making people cringe (because they cost $6 when purchased in bulk)... There may be something worth salvaging here for minimal investment. I'd be surprised, though. If you are looking for better-quality sound reproduction, you might be better off passing these along to someone who will appreciate them and building something more to your liking.