It's to unfortunate that drivers are so hard to pull apart, otherwise just upgrading a few would be pretty nice! 🙂 😎
This one has been mentioned before, but by most accounts it's a Dayton RS 8" for about half the price:
https://www.newark.com/mcm-audio-select/55-5670/8-die-cast-woofer-8-ohm-rubbber/dp/95Y2936
Here is Tim's results of the 6.5" version (that's no longer available):
Subtract 10.5 db for actual spl 1w/1meter:
http://feleppa.com.au/pics/speaker_imgs/plots/MCM555665_FreqResp.png
Non-Linear: (2nd order is higher, but everything else is not ..at least above 50 Hz) The stiff suspension (spider) helps with this.
http://feleppa.com.au/pics/speaker_imgs/plots/MCM555665_RawHarm.png
http://feleppa.com.au/pics/speaker_imgs/plots/MCM555665plus6_RawHarm.png
http://feleppa.com.au/pics/speaker_imgs/plots/MCM555665plus12_RawHarm.png
https://www.newark.com/mcm-audio-select/55-5670/8-die-cast-woofer-8-ohm-rubbber/dp/95Y2936
Here is Tim's results of the 6.5" version (that's no longer available):
Subtract 10.5 db for actual spl 1w/1meter:
http://feleppa.com.au/pics/speaker_imgs/plots/MCM555665_FreqResp.png
Non-Linear: (2nd order is higher, but everything else is not ..at least above 50 Hz) The stiff suspension (spider) helps with this.
http://feleppa.com.au/pics/speaker_imgs/plots/MCM555665_RawHarm.png
http://feleppa.com.au/pics/speaker_imgs/plots/MCM555665plus6_RawHarm.png
http://feleppa.com.au/pics/speaker_imgs/plots/MCM555665plus12_RawHarm.png
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Thanh, the measured HD magnitude on the RS125-4 was with a normal healthy and unmolested drive unit.
Yeah for EU people not very interesting because of the heavy shipping costs (and probably import fees). 🙁
Some of them also seem to be sticking around for a while, looking at the restocking dates etc.
I really would like to see some measurements of that one though.
Another idea for north Americans;
https://www.madisoundspeakerstore.com/approx-8-woofers/silver-flute-w20rc38-08-8-wool-cone/
Interesting:
Going to the Swiss section of Newark mentions that the 8" driver won't be manufactured anymore:
All the stock is coming from the US (even though it's China-sourced) and there does appear to be a SINGLE Delivery surcharge depending on the *country in the EU; but it should still be cheap for 2 or more drivers.
ex. 16 Euros for Austria for as many as you purchase with each driver at almost 42 Euros.
It's kind'of moot though for Jim if he can't rely on a supply for Family/Friends sourcing them in the future.
Going to the Swiss section of Newark mentions that the 8" driver won't be manufactured anymore:
All the stock is coming from the US (even though it's China-sourced) and there does appear to be a SINGLE Delivery surcharge depending on the *country in the EU; but it should still be cheap for 2 or more drivers.
ex. 16 Euros for Austria for as many as you purchase with each driver at almost 42 Euros.
It's kind'of moot though for Jim if he can't rely on a supply for Family/Friends sourcing them in the future.
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Interestingly, here's Hificompass's measurement of the RS125-4
Reference:
https://hificompass.com/ru/speakers/measurements/dayton-audio/dayton-audio-rs125-4
Thanks for the correction Ben.
I had heard conflicting information regarding inductivity control and I'm glad we all now that clarity on the RS matter.
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You know what this means right?
The DIY community are going to have an absolute barn-storming tiny 2-4 way RS passive design from @wolf_teeth in the future...😗
The DIY community are going to have an absolute barn-storming tiny 2-4 way RS passive design from @wolf_teeth in the future...😗
That's often my experience with Faital drivers. While they look good/great on paper they never compete with the best in class.
And I never measured the same as a Faital or Dayton (or TB Speaker) "Data"sheet ... other companies give more reliable data.
I also wonder if the high H3 of SB Acoustics at low frequencies is intentional done? H5 and higher is still low, H2 is good. Strange.
Some H3 at low frequencies sounds good! It suggests "tight" bass.
(I just remember now - that's what a quick listening comparison of SB29NRX75-6 to my ScanSpeak 8" also showed. The SB was more "tight", ScanSpeak more "black")
A fixed "Phase plug" means air gap. RS225 uses it and wouldn't that be a problem with sealed box, as Jim is planning to make? Signature line don't use plugs, like most other candidates that have been mentioned.
https://www.diyaudio.com/community/threads/phase-plug.192215/
https://www.audiosciencereview.com/...hase-plug-for-sealed-cabinet-mix-cubes.31934/
https://www.diyaudio.com/community/threads/phase-plug.192215/
https://www.audiosciencereview.com/...hase-plug-for-sealed-cabinet-mix-cubes.31934/
Oh yes of course you are right there is a slight air gap for the RS225 or other drivers due to the use of a stationary phase plug.
Though with a small air gap I don't think it's a problem from sealed box/LT point of view. Sigfried Linkwitz was an proponent of using air gaps for sealed box subwoofers with "a small pin hole (<1 mm diameter) to equalize internal with external static pressure and to prevent displacing the cone from its normal resting position."
Reference:
https://www.linkwitzlab.com/thor-design.htm
Though with a small air gap I don't think it's a problem from sealed box/LT point of view. Sigfried Linkwitz was an proponent of using air gaps for sealed box subwoofers with "a small pin hole (<1 mm diameter) to equalize internal with external static pressure and to prevent displacing the cone from its normal resting position."
Reference:
https://www.linkwitzlab.com/thor-design.htm
I think this whole idea is/was a bit far fetched.
I have actually never encountered cases where a woofer was so substantially off from the resting position to get any significant performance issues.
Given that temperature and humidity is relatively constant and/or change very gradually, I have also a very difficult time believing this would even cause any major issues.
This would only be true when a certain enclosure is hermetically sealed.
Which is quite the challenge to do, a material only has to be a teeny tiny little porous to be enough.
I have also never seen any further research into this subject as well btw.
So it just sits there as a hypothesis.
OK I’m with you both in this teeny hole in a sealed box topic.
And intuitively it makes sense for me too.. But sometimes intuition or appeal to authority can be wrong.
But what science depends on is empirical evidence.
A whistle, if audible, should be measurable, no? At least in an amplitude response or in the the harmonic distortion plot?
Besides, I know some people who, try as they might, can blow, but cannot whistle.
🤣
But for the record, Jim, I have never put a pinhole in my sealed box subwoofers. And I don’t believe that the RS225 has a problem in a sealed box.
And intuitively it makes sense for me too.. But sometimes intuition or appeal to authority can be wrong.
But what science depends on is empirical evidence.
A whistle, if audible, should be measurable, no? At least in an amplitude response or in the the harmonic distortion plot?
Besides, I know some people who, try as they might, can blow, but cannot whistle.
🤣
But for the record, Jim, I have never put a pinhole in my sealed box subwoofers. And I don’t believe that the RS225 has a problem in a sealed box.
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That depends on the motor is being constructed.
As far as I know the RS225 doesn't have any vent holes on the back?
The one hole on the back, I think is just a blind hole, to to screw in the phase plug?
Correct me if I am wrong (I haven't seen one in person in a long time).
So this means that the air directly inside the magnet structure has to go somewhere.
This case to the front via the phase plug.
Which is probably a good thing to begin with.
If the hole on the back IS open to the inner magnet structure, you're obviously correct.
It works a little different for woofers that have an opening on the sides of the front side of the spider.
(jeez what a sentence, lol)
edit: Now I am thinking about it.
You can't have a phase plug AS WELL as openings on the back/side at the same time.
Since this will create a direct open path to the enclosure.
edit 2: But apparently some woofers do have this. Interesting and fascinating....
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I once had a project where I needed to produce quick changing static pressure. So I needed to build a REALLY sealed pressure chamber.
For this task I used a 8" PA like speaker with thick paper membrane and rubber surround and a special rubber sealing directly to that rubber surround (and a few other tricks to get that volume sealed). And still I could not produce static pressure, there was a leak.
Until I coated that thick paper membrane with a thick laver of black sticky coat stuff. There was air comming through the thick paper membrane - very liiiitle but enough to not be 100% sealed.
The way we build our speakers you never get 100% sealed - no way. And you don't need to at all, just get a low enough corner frequency of that leakage.
I have a very sophisticated way to get that controlled leakage - I screw my Speakon sockets without additional sealing into the housing. 😎 Never had any noises or troubles from that and for sure you are not 100% sealed.
A phase plug will make a path around the coil and through the spider into the housing - that's the best way without any additional openings in the basket.
I would test if there are noises when the speaker sits in the box and doing large membrane movements at 10Hz. And check if Q is significant lower as expected (so Q leakage of the bos would be very large). If that's fine you should be fine.
But when possible I stay away from phase plugs for low frequency closed speakers.
Btw - the frequency response IN the pressure chamber. SPL is calibrated. 1/4" pressure mic is needed for that.
I agree with this. No wood/mdf/plywood box is going to be air tight, to the point where it could maintain a few millibar pressure differential over a long term (i.e. hours or days)... and this is the level of "air tightness" that would be required before we would have to worry about equalizing atmospheric pressure.