Hi Everyone,
I'm trying to build 3 way speakers as a project and after coming to the point of choosing the drivers (and ordering), simulating the HP/LP filters and almost getting seemingly right crossovers with smooth SPL, I realized I was dipping to impedance as low as 2 ohms (graph attached).
I searched around for this, but not sure what I'm doing wrong and there is a lot that could be wrong. For a starting point I wanted to gain more knowledge on whether I have chosen the right drivers for this project.
Description:
Sub Woofer: Peerless 5-1/4" 4 Ohm (https://www.parts-express.com/pedoc...-p830945-paper-cone-woofer-specifications.pdf)
Mid Range: Tang Bang 4" 4 Ohm (https://www.parts-express.com/pedocs/specs/264-872-tang-band-w4-1720-specifications-45770.pdf)
Tweeter: Peerless 4 Ohm (https://www.parts-express.com/pedocs/specs/264-1012--tymphany-xt25bg60-04-spec-sheet.pdf)
I realize these are compact and powerful drivers but I'm not sure if they are right for my design. I want to make a 3 way crossover speaker, which is really the design goal. I also thought of adding a second of the same sub for a little more oomph on the low range but only to end up with worse impedance.
I think I need to choose different drivers maybe (mids with 8ohm?), but then I've read the whole point of a crossover network is to cross them over at the same impedance and avoid silly phase plots.
Or is it possible to work with these drivers (and possibly add another sub?) and I need to cross them over with the correct filters? I can post my designs with the crossover filters if anyone would like to have a look at it. I plan to read up more, and try some new crossover and filter designs this weekend but I want to make sure I'm not starting out with wrong drivers.
Any help is much appreciated!
Thanks!
I'm trying to build 3 way speakers as a project and after coming to the point of choosing the drivers (and ordering), simulating the HP/LP filters and almost getting seemingly right crossovers with smooth SPL, I realized I was dipping to impedance as low as 2 ohms (graph attached).
I searched around for this, but not sure what I'm doing wrong and there is a lot that could be wrong. For a starting point I wanted to gain more knowledge on whether I have chosen the right drivers for this project.
Description:
Sub Woofer: Peerless 5-1/4" 4 Ohm (https://www.parts-express.com/pedoc...-p830945-paper-cone-woofer-specifications.pdf)
Mid Range: Tang Bang 4" 4 Ohm (https://www.parts-express.com/pedocs/specs/264-872-tang-band-w4-1720-specifications-45770.pdf)
Tweeter: Peerless 4 Ohm (https://www.parts-express.com/pedocs/specs/264-1012--tymphany-xt25bg60-04-spec-sheet.pdf)
I realize these are compact and powerful drivers but I'm not sure if they are right for my design. I want to make a 3 way crossover speaker, which is really the design goal. I also thought of adding a second of the same sub for a little more oomph on the low range but only to end up with worse impedance.
I think I need to choose different drivers maybe (mids with 8ohm?), but then I've read the whole point of a crossover network is to cross them over at the same impedance and avoid silly phase plots.
Or is it possible to work with these drivers (and possibly add another sub?) and I need to cross them over with the correct filters? I can post my designs with the crossover filters if anyone would like to have a look at it. I plan to read up more, and try some new crossover and filter designs this weekend but I want to make sure I'm not starting out with wrong drivers.
Any help is much appreciated!
Thanks!
Attachments
Hi,
Do you have a amp that can handle this 2 ohm minimum, if so not a real problem as you don't have huge reactance swings at that frequency which would make things more difficult for the amp.
Theoretically a second woofer wired in series will increase the overall impedance, you may then adjust the midrange values to maybe come away from the existing low, aiming to get back up towards at least 4 ohms. You may have to sacrifice some flatness in the response as you play with components to give you a reasonable compromise.
Have you modelled the enclosure for baffle step, as that usually adds some more inductance to a design, but your chosen woofer has a very low inductance already so I guess you don't need to add many mH's to compensate for baffle step. Also are you using any additional capacitance in parallel with the woofer?
Run the additional woofer in your simulations, and if it doesn't provide a sensible impedance and solution, post your design, you may need to provide the necessary frd and zma files for others to help?
Look at Troels Gravesen's classic 3 way designs to see the impedances he gets using various drivers for three way designs. I guess they are bigger than what you were aiming for?
Regards,
Ray
Do you have a amp that can handle this 2 ohm minimum, if so not a real problem as you don't have huge reactance swings at that frequency which would make things more difficult for the amp.
Theoretically a second woofer wired in series will increase the overall impedance, you may then adjust the midrange values to maybe come away from the existing low, aiming to get back up towards at least 4 ohms. You may have to sacrifice some flatness in the response as you play with components to give you a reasonable compromise.
Have you modelled the enclosure for baffle step, as that usually adds some more inductance to a design, but your chosen woofer has a very low inductance already so I guess you don't need to add many mH's to compensate for baffle step. Also are you using any additional capacitance in parallel with the woofer?
Run the additional woofer in your simulations, and if it doesn't provide a sensible impedance and solution, post your design, you may need to provide the necessary frd and zma files for others to help?
Look at Troels Gravesen's classic 3 way designs to see the impedances he gets using various drivers for three way designs. I guess they are bigger than what you were aiming for?
Regards,
Ray
A 3 way with a 5" midwoofer, a 4" midwoofer and a 1" tweeter doesn't make much sense. Why have you opted for these drivers?
Examples of competent small bookself 3 ways are:
- 8" woofer, 3" midrange, 1" tweeter here.
- 6.5" woofer, 2" midrange, 3/4" tweeter here.
If you are building a small floorstanding 3 way then a common combination is 2 x 6.5" woofers, 4" midrange, 1" or 3/4" tweeter here. The woofers would be 8 ohms in parallel to give a nominal 4 ohms. The 4" would be a midrange driver (small xmax, high sensitivity,...) and not a midwoofer in order to match the pair of woofers or, as in the example, a filler driver with additional output from the tweeter or woofer.
I do not have an amp that can handle 2ohm, and I believe most common amps out there are built for 4-6ohm min at most.
Its funny you mentioned putting two subs in series. I did try that out, it pulled the average impedance up but I could not solve the 2 ohm dips.
I don't think I am adding any capacitance in parallel to the sub.
I can post the frd, zma files and all my design files later (they are in my home PC). and I also need to perform some iterations.
I looked at Troel Gravensen's designs and some others by Curt and Zach (please excuse if i mispelled the names), but most of them are too big for me.
Thanks for all of your input and feedback, but do you ultimately think I can make these drivers work with more design iterations and tweeking?
Yes it can work. The 2 ohm dips can be settled with a crossover redesign.
I would however leave out the 5" woofer, as it does not add much to the speakers performance. It only displaces 1.46 times as much air as the 4" woofer. Leaving the 5" woofer out greatly simplifies crossover design and cuts on crossover costs. The 5" woofers can be reused if you build separate subwoofers with them and power them from a separate amplifier. Then you would have four low frequency energy sources to spread across the room, which helps to fight room modes.
I would however leave out the 5" woofer, as it does not add much to the speakers performance. It only displaces 1.46 times as much air as the 4" woofer. Leaving the 5" woofer out greatly simplifies crossover design and cuts on crossover costs. The 5" woofers can be reused if you build separate subwoofers with them and power them from a separate amplifier. Then you would have four low frequency energy sources to spread across the room, which helps to fight room modes.
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I opted for these drivers because I wanted a somewhat compact but powerful floorstanding speaker kit. It seemed like each of these drivers are powerful individually, but due to lack of knowledge, I did not anticipate they might not work well together.
However in retrospect I think I can go up to 6.5" for the subwoofer. Its not that big.
I have a few questions for you based on your reply.
1. I thought I was using a Sub Woofer, Mid Range, and Tweeter. ("A 3 way with a 5" midwoofer, a 4" midwoofer and a 1" tweeter doesn't make much sense") Can you please elaborate on what kind of drivers work together.
2. Do you think thta for my design I can keep the tweeter and midrange, and opt for different subwoofers. (some 8ohms) - Following on that - Does it have to be two 8 ohm subs. Cant I just get one sub, connect it to 8ohm Res in Parrallel and get that 4 ohms.
3. In regards to the design you hyperlinked in your reply, that contains two subs, a full range driver and a tweeter. (is it a good example of a 3 way?)
4. I dont want a lot of bass. I like clear and crisp sound with some bass over huge thumping bass. Given that, I assumed hig quality (mid and sub) drivers would give me good quality of sound and I chose the best drivers I could find right under my budget. Wrong approach?
I know I have opened a huge can of worms, but I really appreciate your time and feedback.
I agree with you! Even in the SPL simulations, the sub woofers wasnt doing much @ over 60-65 Hz.
Would you rather recommend getting different 5 - 6.5inch sub woofer drivers.
I really appreciate your opinion, but 3 way is kind of the design goal. It might not turn out perfect and I don't mind having to take it all apart in the end to design and build the crossovers again. I have a decent budget and good experience in circuit design and debugging ( did 200 300 electrical courses in college but then deviated to computer hardware, so I've lost hold of my electrical basics but I can brush up) so I'm not afraid to tackle it.
Please feel free to post and direct me to resources you guys feel might be helpful for me!
Thanks
You could use either midwoofer with the tweeter and make an inefficient OK(ish) small 2 way.
I would suggest that buying the crossover parts for a 3 way with the current set of drivers is throwing good money after bad. If you want a 3 way then the tweeter is OK but neither midwoofer makes much sense except for 2 ways. They are both 4 ohm not 8 ohm and so you would need 3 more not 1 more for a nominal 4 ohm load. Two in series would be inefficient even without baffle step correction.
Unless an active crossover is an option or your crossover parts are free then I would suggest dropping the design, returning/selling both midwoofers and buying appropriate woofer(s) and midrange after a bit more homework.
I appreciate your concerned reply. I too think I did not do my homework before ordering the parts. I kinda slacked after getting the SPL and failed to do more diligent research.
Fortunately for me, I can return all of the parts.
I'm going to do some homework, find some new drivers, design new crossover and post my designs here by end of day today (hopefully!)
Before diving in I had one more question:
I now know to look at sensitivity and resitance when looking at drivers.
What kind of frequency ranges should I be looking at for my sub woof and mid if I want an 'Efficient' 3 way. I dont want to get drivers bigger than 6 / 6.5 inch at most.
You can return drivers if it hasn't been past the deadline. You may want to look at some finished designs for ideas. Visaton, Madisound, Parts Express, Zaph Audio all have designs that have documented performance that you can directly copy or use for ideas on what drivers work well together and what volume enclosure to use.
@andy19191,
please ignore my last post to you.
I just found this your reply below on a different thread. I think its the information I needed.
COPIED POST BELOW:
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Quote:
Originally Posted by Ugg10 View Post
Thanks @andy19191 for the comment.
Reviews seem to point to this being one of the best 6.5” to 7” drivers that can also dig fairly deep without going up to an 8” but also be well behaved fairly high.
I would probably plan to cross over at 350-45hz so true subs are probably not going to do it.
Do you have another suggestion for a more cost effective driver that can get down below 30hz f3 in a vented floor standers at 6.5-7” and give a punchy bass?
Do the mid/tweeter look ok?
I am open to suggestions as I am feeling my way into this.
A 6.5" + 1" 2 way is a budget configuration that asks too much of the midwoofer which is too small to perform bass duties well (distorts due to insufficient SPL) and too large to handle the upper midrange well (cone too big and resonates). It is also common to cross the tweeter too low (distorts due to insufficient SPL). It is however an excellent configuration for modestly small priced speakers. Because the drivers are being asked to do too much expensive exotic drivers are likely to bring audible benefits.
A 2 x 8" + 5" + 1" 3 is perhaps the standard high fidelity 3 way combination where things are nicely balanced. Note the 5" needs to be an efficient midrange driver for things to drop nicely into place and not the currently more common small midwoofer.
Now I think you are saying that 8" woofers are too big? And you want 30 Hz performance? And sound quality is relevant (which requires room boom removal => distributed subs and more cone area!).
One 6.5" driver will struggle with deep bass, two would be a significant improvement but four would be needed to match the area of 2 x 8" but then the stroke will be shorter and so not quite.
Decent 2 x 6.5" standard range drivers will outperform every 1 x 6.5" exotic range driver as a woofer in a 3 way. Since you are opting for a floor standing speaker this is not a problem. Unfortunately 6.5" is a bit small for a woofer and the perfect size for a midwoofer and so there are almost no off the shelf drivers with parameters optimised for woofer duty. Standard woofers tend to be 8" and above in size.
I would suggest settling on a configuration first before looking closely at driver details. 2 x 6.5" + 4" + 1" in a small tower might be what you are after? but you may have to accept the laws of physics when it comes to low frequency output. ""
Thanks again
please ignore my last post to you.
I just found this your reply below on a different thread. I think its the information I needed.
COPIED POST BELOW:
""
Quote:
Originally Posted by Ugg10 View Post
Thanks @andy19191 for the comment.
Reviews seem to point to this being one of the best 6.5” to 7” drivers that can also dig fairly deep without going up to an 8” but also be well behaved fairly high.
I would probably plan to cross over at 350-45hz so true subs are probably not going to do it.
Do you have another suggestion for a more cost effective driver that can get down below 30hz f3 in a vented floor standers at 6.5-7” and give a punchy bass?
Do the mid/tweeter look ok?
I am open to suggestions as I am feeling my way into this.
A 6.5" + 1" 2 way is a budget configuration that asks too much of the midwoofer which is too small to perform bass duties well (distorts due to insufficient SPL) and too large to handle the upper midrange well (cone too big and resonates). It is also common to cross the tweeter too low (distorts due to insufficient SPL). It is however an excellent configuration for modestly small priced speakers. Because the drivers are being asked to do too much expensive exotic drivers are likely to bring audible benefits.
A 2 x 8" + 5" + 1" 3 is perhaps the standard high fidelity 3 way combination where things are nicely balanced. Note the 5" needs to be an efficient midrange driver for things to drop nicely into place and not the currently more common small midwoofer.
Now I think you are saying that 8" woofers are too big? And you want 30 Hz performance? And sound quality is relevant (which requires room boom removal => distributed subs and more cone area!).
One 6.5" driver will struggle with deep bass, two would be a significant improvement but four would be needed to match the area of 2 x 8" but then the stroke will be shorter and so not quite.
Decent 2 x 6.5" standard range drivers will outperform every 1 x 6.5" exotic range driver as a woofer in a 3 way. Since you are opting for a floor standing speaker this is not a problem. Unfortunately 6.5" is a bit small for a woofer and the perfect size for a midwoofer and so there are almost no off the shelf drivers with parameters optimised for woofer duty. Standard woofers tend to be 8" and above in size.
I would suggest settling on a configuration first before looking closely at driver details. 2 x 6.5" + 4" + 1" in a small tower might be what you are after? but you may have to accept the laws of physics when it comes to low frequency output. ""
Thanks again
You want a small 3 way floorstanding speaker. Is 2 x 6.5" woofer OK?
For the woofer you need a lot more area than the midrange. This is not only because lower frequency needs more area for the same SPL but also because the midrange tends to beam forward whereas the woofer tends to radiate equally in all directions. The latter is often called "baffle step correction" and is a tricky part of speaker design influenced by the location of the speaker in the room, baffle size, driver parameters and ease of inclusion in the crossover design.
Depending on how much baffle step correction you opt for the midrange efficiency needs to be roughly this amount below the woofer(s) efficiency although this is affected by baffle size, how much help the midrange gets from the woofer and tweeter and possibly one or two other things.
The 4 ohm load is in order to be nice to amplifiers. What matters for the speaker is matching the SPL of the drivers. If you have a 4" midrange you will typically need about 2 x 6.5" or 1 x 8" woofers for a balanced output. If you drop to only 1 x 6.5" then a 2" midrange would likely be a better match.
It is OK. I had to start qualifying my post when I realized it used the midrange as a filler rather than a conventionally. There aren't many off the shelf midranges around these days.
The quality of the bass is determined mainly by the room not the woofer. If you do nothing to control the room response then a low level of bass may sound preferable.
Yes. You need to design the speaker first then pick appropriate drivers. To get an initial feel look at existing designs. You won't find any competent 5" + 4" + 1" designs. You will typically find 2 x 6.5" woofers possibly with one rolling off to support baffle step correction (3.5 way), 3-4" midrange with 1" tweeter or perhaps 2" upper midrange and 3/4" tweeter. Bookshelf speakers may have only one woofer. After you have settled on a configuration the parameters for suitable drivers will follow (i.e. impedance, sensitivity, max power/SPL,...).
WOW! that was super helpful.
Thanks andy19191!
I'm going to revisit my design, choose new stuff and come back with a better design.
I'd like to get some feedback then please
Thanks again!
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Interesting stuff to think about there, I did think about the fact you could easily get a workable two way going, but I deleted it from my original post to keep it short.
No Harm done as you can return the drivers so that is good.
Either side of the television at a low 1.5 feet could be interesting for a 2 x 6.5 woofer and 1 inch dome tweeter in D'Appolito arrangement. You will find lots of designs I cannot recommend one as I haven't heard any for a while, others here will make recommendations if that's what you want, maybe take some time and do a bit more research.
Another interesting and well documented build guide is here for another two way bass and tweeter, not a D'Appolito however.
SB Acoustics :: Arya Kit
although the listening axis will be a bit nearer 2.5 to 3 feet due to its height which is a typical design value to cater for people sitting down to listen to their music or watch the TV.
No Harm done as you can return the drivers so that is good.
Either side of the television at a low 1.5 feet could be interesting for a 2 x 6.5 woofer and 1 inch dome tweeter in D'Appolito arrangement. You will find lots of designs I cannot recommend one as I haven't heard any for a while, others here will make recommendations if that's what you want, maybe take some time and do a bit more research.
Another interesting and well documented build guide is here for another two way bass and tweeter, not a D'Appolito however.
SB Acoustics :: Arya Kit
although the listening axis will be a bit nearer 2.5 to 3 feet due to its height which is a typical design value to cater for people sitting down to listen to their music or watch the TV.
Here's a nice 7" woofer that digs low and sounds great to base your design around: Anarchy-708. Does it in a relatively small box too.
This driver works very well as a TM, an MTM, a TMM or a TMWW. Pair a couple of them with a 4" or even a 5" driver from HDS Peerless, ScanSpeak Discovery or SB Acoustics (among others) and you'll have yourself a fantastic 3-way speaker. For a smaller footprint and a little less output capability, a single woofer in a TMW with a 3" or 4" mid should also work out very nicely, although to be honest, I'm not 100% sure that the extra expense there would be warranted over just going with the simpler TM or MTM.
This driver works very well as a TM, an MTM, a TMM or a TMWW. Pair a couple of them with a 4" or even a 5" driver from HDS Peerless, ScanSpeak Discovery or SB Acoustics (among others) and you'll have yourself a fantastic 3-way speaker. For a smaller footprint and a little less output capability, a single woofer in a TMW with a 3" or 4" mid should also work out very nicely, although to be honest, I'm not 100% sure that the extra expense there would be warranted over just going with the simpler TM or MTM.
Just curious, why are you set on doing a 3 way? It's totally fine if that's just what you want to do, but if the reason for it is so that you can achieve some other design goal, then it may be that you can achieve that more effectively in another way.
It might be helpful too if you tell us a little bit more about what you're trying to achieve with these speakers too. So far I see small and floorstander and 3 way as your goals.
Do you have other goals as well? Things like max SPL or F3 frequency? Intended use (i.e. home theater, music, etc)? If we know those we might be able to help point you in the right direction more effectively!
I'm looking forward to seeing how the project goes for you!
It might be helpful too if you tell us a little bit more about what you're trying to achieve with these speakers too. So far I see small and floorstander and 3 way as your goals.
Do you have other goals as well? Things like max SPL or F3 frequency? Intended use (i.e. home theater, music, etc)? If we know those we might be able to help point you in the right direction more effectively!
I'm looking forward to seeing how the project goes for you!
Here are my random thoughts.
Goals are important. Knowing what you are shooting for and what your compromises are is a key to success.
Questions like:
How large is your room.
How much power does your amp have?
Is your amp stable into low Z loads.
How loud do you need to play?
What speaker dimensions are you willing to live with?
A 2 way with a 7' driver in a .75 Cu Ft box can have stunning base.
I helped build a Modula MT and it was great.
My brother built a 4" full range in a 1/4 CU Ft box and added a 3/4" tweeter with an L pad and a Cap.
It wasn't as efficient or as loud, but it was nice in a small room.
Good luck with your project.
Goals are important. Knowing what you are shooting for and what your compromises are is a key to success.
Questions like:
How large is your room.
How much power does your amp have?
Is your amp stable into low Z loads.
How loud do you need to play?
What speaker dimensions are you willing to live with?
A 2 way with a 7' driver in a .75 Cu Ft box can have stunning base.
I helped build a Modula MT and it was great.
My brother built a 4" full range in a 1/4 CU Ft box and added a 3/4" tweeter with an L pad and a Cap.
It wasn't as efficient or as loud, but it was nice in a small room.
Good luck with your project.
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