Have been playing with a set of ex-cinema Martin Audio Effect 5s
https://martin-audio.com/downloads/archive/datasheets/Effect5datasheet.pdf
They're a 2 way design with a horn tweeter and a 10" woofer in a 35 litre ported "reflex" enclosure. They're designed for use as surrounds in a cinema - originally wall mounted, the cabinet is a trapezoidal shape so the drivers are angled downwards towards the listener.
They sound pretty nice. Very efficient and "fast", wide dispersion, great dynamics, loads of volume and impact. Being critical they're perhaps a bit boom and tizz in balance, not much in the way of deep bass (but plenty of punch and midbass) and perhaps a bit sucked out in the midrange /presence area. Specs claim 75Hz-20kHz ±3dB which sounds about right to me.
The shape and orientation of the cabinets is such that stand mounting is difficult, so I've been wondering whether they could be improved with some new cabinets, either large standmounters or floor-standing. I'm fairly sure that more rigid, internally braced construction and a little more care in damping/lagging would bring about improvements but am also wondering whether bigger, possibly sealed cabinets would offer better bass extension and clarity.
I can't find t/s measurements for the driver but it appears to have a relatively compliant suspension and low-ish resonance which makes me think it might work OK in a larger sealed box. I'm fairly sure these 10" woofers are capable of better bass than they're currently providing.
Would welcome thoughts on how best to proceed - I realise there's going to be a fair bit of guesswork involved so good to have some input.
https://martin-audio.com/downloads/archive/datasheets/Effect5datasheet.pdf
They're a 2 way design with a horn tweeter and a 10" woofer in a 35 litre ported "reflex" enclosure. They're designed for use as surrounds in a cinema - originally wall mounted, the cabinet is a trapezoidal shape so the drivers are angled downwards towards the listener.
They sound pretty nice. Very efficient and "fast", wide dispersion, great dynamics, loads of volume and impact. Being critical they're perhaps a bit boom and tizz in balance, not much in the way of deep bass (but plenty of punch and midbass) and perhaps a bit sucked out in the midrange /presence area. Specs claim 75Hz-20kHz ±3dB which sounds about right to me.
The shape and orientation of the cabinets is such that stand mounting is difficult, so I've been wondering whether they could be improved with some new cabinets, either large standmounters or floor-standing. I'm fairly sure that more rigid, internally braced construction and a little more care in damping/lagging would bring about improvements but am also wondering whether bigger, possibly sealed cabinets would offer better bass extension and clarity.
I can't find t/s measurements for the driver but it appears to have a relatively compliant suspension and low-ish resonance which makes me think it might work OK in a larger sealed box. I'm fairly sure these 10" woofers are capable of better bass than they're currently providing.
Would welcome thoughts on how best to proceed - I realise there's going to be a fair bit of guesswork involved so good to have some input.
Not looking for more bass - cleaner bass with more extension would be nice if it’s achievable.
Have set them up on stands previously and enjoyed the sound but the dimensions and shape of the speaker make them impractical in a domestic environment - they inevitably take up more space than needed, they are also fairly ugly, and being top heavy tend towards being unstable. As much as anything I’d like to make them look nicer.
Subwoofer is not part of the plan, essentially I’m just looking to get these drivers to perform as well as possible in a domestically acceptable cabinet.
Good thought re blocking the port - at least to see how the driver performs - could also try adding some wadding to the cabinet. Gut feeling is a bigger box would help but I could be wrong.
Have set them up on stands previously and enjoyed the sound but the dimensions and shape of the speaker make them impractical in a domestic environment - they inevitably take up more space than needed, they are also fairly ugly, and being top heavy tend towards being unstable. As much as anything I’d like to make them look nicer.
Subwoofer is not part of the plan, essentially I’m just looking to get these drivers to perform as well as possible in a domestically acceptable cabinet.
Good thought re blocking the port - at least to see how the driver performs - could also try adding some wadding to the cabinet. Gut feeling is a bigger box would help but I could be wrong.
Hello!
Looking at your speakers, it seams each port is a 2-inch diameter. Is that correct? I just guessed by comparing with woofer diameter.
Considering the enclosure depth available, I guess each port is around 4 to 5 inch long, is that correct?
Could you measure and get the exact diameter and depth? Then we can determine the tuning frequency of this enclosure.
Considering the volume and the guesses port dimensions, it seams this enclosure was tuned around 48Hz, which is why bass don't get extended.
Test you can do: close one of the ports. This will drop the tuning frequency from 48Hz to around 34Hz.
Listen and check what you get. You should get a less boomy response and more extended bass.
If you move the speakers to a bigger floor standing enclosure, let's say with 80 liters, you can probably improve the bass extension by several dB's.
Without speaker T/S parameters, you can play with the tuning frequency and adjust it by trial and error using different lengths.
Start with a single 3-inch diameter and try different lengths.
See below a simulation with a 10-inch speaker (just as an example) with supposed parameters: 35 liters, 2-inch diameter ports 4.4-inch long ports
RED: 35 liters, 2 ports (tuning freq=48Hz)
BLUE: 35 liters, 1 port (tuning freq=34Hz)
GREEN: 80 liters, 1 port of 3-inch 5.2 inch long (tuning freq=30Hz)
See the huge difference between 30Hz and 40Hz
Looking at your speakers, it seams each port is a 2-inch diameter. Is that correct? I just guessed by comparing with woofer diameter.
Considering the enclosure depth available, I guess each port is around 4 to 5 inch long, is that correct?
Could you measure and get the exact diameter and depth? Then we can determine the tuning frequency of this enclosure.
Considering the volume and the guesses port dimensions, it seams this enclosure was tuned around 48Hz, which is why bass don't get extended.
Test you can do: close one of the ports. This will drop the tuning frequency from 48Hz to around 34Hz.
Listen and check what you get. You should get a less boomy response and more extended bass.
If you move the speakers to a bigger floor standing enclosure, let's say with 80 liters, you can probably improve the bass extension by several dB's.
Without speaker T/S parameters, you can play with the tuning frequency and adjust it by trial and error using different lengths.
Start with a single 3-inch diameter and try different lengths.
See below a simulation with a 10-inch speaker (just as an example) with supposed parameters: 35 liters, 2-inch diameter ports 4.4-inch long ports
RED: 35 liters, 2 ports (tuning freq=48Hz)
BLUE: 35 liters, 1 port (tuning freq=34Hz)
GREEN: 80 liters, 1 port of 3-inch 5.2 inch long (tuning freq=30Hz)
See the huge difference between 30Hz and 40Hz
Had a quick look at WinISD and it looks as if ports are tuned to roughly 57hz? Although I can't work out how to work out tuning from length - I am having to work backwards if that makes sense as port length is greyed out.
I think a bigger box and lower port frequency is probably the way to go.
I think a bigger box and lower port frequency is probably the way to go.
Hi!
Yes, I checked here. With 2 ports of 2" diameter and 2.5" long, the tuning frequency is 57Hz - very high, indeed, limiting all the bass extension.
In latest WinISD you have to change the tuning frequency and the port length changes accordinly.
Kind of iterative process, unfortunatelly - unless, I'm missing something.
In older releases, we could change length and the tuning frequency would change.
Anyways, It's just a matter of iterate and get the results.
In this case, if the port length is 2.5", if you close one of the ports, the tuning frequency will be 41.5Hz.
5 to 6dB is expected to increase between 30 and 40Hz and the boomy response will be attenuated in the region of 50 to 90Hz.
If there is room, you can insert a 2" diameter thick paper tube of 5" or 6" inside the existing port to test the sound of a longer port.
Easy, cheap and nothing to loose if it doesn't work.
For sure, with a big enclosure and a lower tuning frequency, frequency response will be better in the low bass region.
Yes, I checked here. With 2 ports of 2" diameter and 2.5" long, the tuning frequency is 57Hz - very high, indeed, limiting all the bass extension.
In latest WinISD you have to change the tuning frequency and the port length changes accordinly.
Kind of iterative process, unfortunatelly - unless, I'm missing something.
In older releases, we could change length and the tuning frequency would change.
Anyways, It's just a matter of iterate and get the results.
In this case, if the port length is 2.5", if you close one of the ports, the tuning frequency will be 41.5Hz.
5 to 6dB is expected to increase between 30 and 40Hz and the boomy response will be attenuated in the region of 50 to 90Hz.
If there is room, you can insert a 2" diameter thick paper tube of 5" or 6" inside the existing port to test the sound of a longer port.
Easy, cheap and nothing to loose if it doesn't work.
For sure, with a big enclosure and a lower tuning frequency, frequency response will be better in the low bass region.
I guess they're designed to give a strong upper bass output for the size rather than a clean and extended hi-fi sound. Would have been used with big subs in a cinema setup. Drivers aren’t super high quality IMO but they’re pretty decent and more hi-fi than PA.
I’m wondering how the cabinet might affect midrange performance. Also wondering whether being leaner in the mid bass will mean the treble appears a bit more strident. Might have to tame the tweeters slightly. That’s a long way off though!
I’m wondering how the cabinet might affect midrange performance. Also wondering whether being leaner in the mid bass will mean the treble appears a bit more strident. Might have to tame the tweeters slightly. That’s a long way off though!
Hi! I agree. This is a typical design for high efficiency rather than linearity.
And, yes, bass should come from additional subs for this type of speaker.
But that doesn't mean you cannot change things and try different solutions.
You might need some adjustments between woofer and mid/high, cause that tuning at 57Hz is probably reinforcing the frequency response.
But that's the joy of playing with things by ourselves.
Try tuning low firstly and see the result. Note that the pipe doesn't need to be inside the box, at least for testing.
If you like the result, then, you can put it inside.
I've built some speakers recently with 38liters and 10" speakers, but tuned to 28Hz.
The result is quite good.
And, yes, bass should come from additional subs for this type of speaker.
But that doesn't mean you cannot change things and try different solutions.
You might need some adjustments between woofer and mid/high, cause that tuning at 57Hz is probably reinforcing the frequency response.
But that's the joy of playing with things by ourselves.
Try tuning low firstly and see the result. Note that the pipe doesn't need to be inside the box, at least for testing.
If you like the result, then, you can put it inside.
I've built some speakers recently with 38liters and 10" speakers, but tuned to 28Hz.
The result is quite good.
Have set these up in my studio space and done some listening/tweaking. They are now pretty well positioned on some high shelves that I've managed to clear recently, although I couldn't make them work in the living room...
I tried them standard, with one port blocked, and with a bit of rolled up cardboard shoved in the tube, resulting in a 7" port (edit: I don't have WinISD to hand to calculate port frequency here). Due to the slim depth of the cabinet the tube had to be extended out the front of the baffle...
As standard they are pleasantly punchy but with no real bass apparent. The overall impression is of a well judged response for the chosen application, but not really hi-fi.
With one port blocked bass becomes much more impressive with plenty of extension and weight. The effect of the port is audible but it's an enjoyable balance. Upper bass appears perhaps slightly recessed (less "punch") and I began to notice the transition to the tweeter more clearly, you can hear it taking over at about 2k.
With the long port I did not hear any obvious output from the port itself when listening up close. In my normal listening position the sound/bass was really good - no apparent boom but well-extended. Less oompf than above but less colouration. I could detect the impact of the port as a slight slowness in the lowest bass registers. Not unpleasant and perhaps adding to the overall sense of "weight".
Overall they are particularly enjoyable with electronic music and some rock due to excellent dynamics and timing, but the balance is slightly too uneven for acoustic recordings to be really rewarding. I think I could knock a couple of dBs off the tweeter, the upper treble isn't too strident but it would be helpful to smooth the transition in the lower treble/upper mid.
My daughter came in and had a listen. She preferred either standard or with the extended port, with a preference for the latter. Wasn't keen on the single ported sound. I had been enjoying it, but I am a bass-head!
Hopefully I'll get a chance to do some more listening later, I'd like to compare the long port vs completely sealed.
I tried them standard, with one port blocked, and with a bit of rolled up cardboard shoved in the tube, resulting in a 7" port (edit: I don't have WinISD to hand to calculate port frequency here). Due to the slim depth of the cabinet the tube had to be extended out the front of the baffle...
As standard they are pleasantly punchy but with no real bass apparent. The overall impression is of a well judged response for the chosen application, but not really hi-fi.
With one port blocked bass becomes much more impressive with plenty of extension and weight. The effect of the port is audible but it's an enjoyable balance. Upper bass appears perhaps slightly recessed (less "punch") and I began to notice the transition to the tweeter more clearly, you can hear it taking over at about 2k.
With the long port I did not hear any obvious output from the port itself when listening up close. In my normal listening position the sound/bass was really good - no apparent boom but well-extended. Less oompf than above but less colouration. I could detect the impact of the port as a slight slowness in the lowest bass registers. Not unpleasant and perhaps adding to the overall sense of "weight".
Overall they are particularly enjoyable with electronic music and some rock due to excellent dynamics and timing, but the balance is slightly too uneven for acoustic recordings to be really rewarding. I think I could knock a couple of dBs off the tweeter, the upper treble isn't too strident but it would be helpful to smooth the transition in the lower treble/upper mid.
My daughter came in and had a listen. She preferred either standard or with the extended port, with a preference for the latter. Wasn't keen on the single ported sound. I had been enjoying it, but I am a bass-head!
Hopefully I'll get a chance to do some more listening later, I'd like to compare the long port vs completely sealed.
Hi!
Good! It seams the results are what was expected.
You've got a reduction in mid/high bass (>50Hz) and some improvement in the low bass (<50Hz).
With 7 inch long, you get the enclosure tuned to 28.5Hz - that's a good option and that's what I use for some small enclosures (38 liters) I've built for studio monitor.
You may also try a shorter pipe of, let's say 4 inches to see an intermediate option.
Here are the 3 options using the 10" speaker I have as an example (this is the woofer I'm using in my small speakers):
Blue: 28.5Hz
Red: original with 2 ports active (57Hz)
Green: Sealed
Low tuning (below 30Hz), for small volumes, is most of the times the best solution, since you don't get a boomy sound (gain) but get the side effect of port boost just to complement the frequency response when it rolls off. And still get a similar response to the sealed version (you can try and confirm).
See the group delay response.
I think most complains about ported enclosures are related to the use (or bad use) of port to provide gain above the flat curve such as in your case just to sound louder with less power. When you move down the port tuning to just complement the rolloff, you loose that "efficiency" but the result is much better in terms of flatness.
Good! It seams the results are what was expected.
You've got a reduction in mid/high bass (>50Hz) and some improvement in the low bass (<50Hz).
With 7 inch long, you get the enclosure tuned to 28.5Hz - that's a good option and that's what I use for some small enclosures (38 liters) I've built for studio monitor.
You may also try a shorter pipe of, let's say 4 inches to see an intermediate option.
Here are the 3 options using the 10" speaker I have as an example (this is the woofer I'm using in my small speakers):
Blue: 28.5Hz
Red: original with 2 ports active (57Hz)
Green: Sealed
Low tuning (below 30Hz), for small volumes, is most of the times the best solution, since you don't get a boomy sound (gain) but get the side effect of port boost just to complement the frequency response when it rolls off. And still get a similar response to the sealed version (you can try and confirm).
See the group delay response.
I think most complains about ported enclosures are related to the use (or bad use) of port to provide gain above the flat curve such as in your case just to sound louder with less power. When you move down the port tuning to just complement the rolloff, you loose that "efficiency" but the result is much better in terms of flatness.
@ron68 - thank you! I wonder if the group delay graph explains the "slight slowness in the lowest bass registers" I described previously with the lowest port tuning frequency. I suppose the lower the frequency the more audible the effect of the phase relationship between port and direct woofer output? Hence a potential advantage with a sealed box...? As I said previously, it's not unpleasant.
Had a play with some test tones yesterday evening, which confirmed what I'd judged from listening to a range of music. Overall I've really been enjoying the speakers. I can hear the limitations of the smallish box but tuning port frequency lower has made the compromise easier to live with. OTOH it's given me a better idea of what the woofer might be capable of in a bigger box...
So the good is that with the long port, bass and lower midrange output is fairly even down to 40hz - output is still healthy at 30hz, and 20hz is clearly audible. I'd expect low bass to be better with a better amplifier, too - I'm using a wel-abused basic Kenwood integrated to test. It's OK but not brilliant. I bet they'd be great with a smallish valve amp.
The problem area now is around the crossover frequency. According to the specs crossover frequency is 2k - however the tweeter is already overpowering the woofer at 1k. At this frequency the woofers output is still healthy and clean, the level has not dropped significantly from an octave below, but the tweeter is louder and to make matters worse it's exhibiting a "ringing" distortion artifact when playing a 1k sine wave. I wonder if this is the driver itself or the crossover? I'd say that subjectively from roughly 1k to just over 2k the output from the tweeter is (if anything) stronger than the upper treble registers - certainly there is no indication of any roll off below 2k
This all explains the harshness / unevenness in the upper mids. And I'm hoping it means there's room for improvement/tweaks.
I'm in two minds whether I need to look at / alter crossover frequency (probably just for tweeter) or whether there's an easier fix to tame this - First step is going to be pulling the crossover out and having a look - I'll post some photos.
The easy fix to my non-expert mind would just be a simple pad to bring sensitivity for both drivers to an equal point. But maybe there's a cleverer way to smooth the response given the subjective peak in the lower treble. I guess as standard the crossover is set-up to match overall sensitivity based on the boosted midbass response with the original port setup. Makes sense as originally they sounded balanced between (mid)bass and treble but with a hole in the middle. Although it seems counterintuitive to reduce the sensitivity of a horn loaded tweeter in a way - obviously it's been designed with high sensitivity in mind.
I did also wonder whether there was a way to tweak the physical properties of the horn to tame the output, e.g. lining it with wool felt or similar. But I suspect that would be very hit and miss.
Had a play with some test tones yesterday evening, which confirmed what I'd judged from listening to a range of music. Overall I've really been enjoying the speakers. I can hear the limitations of the smallish box but tuning port frequency lower has made the compromise easier to live with. OTOH it's given me a better idea of what the woofer might be capable of in a bigger box...
So the good is that with the long port, bass and lower midrange output is fairly even down to 40hz - output is still healthy at 30hz, and 20hz is clearly audible. I'd expect low bass to be better with a better amplifier, too - I'm using a wel-abused basic Kenwood integrated to test. It's OK but not brilliant. I bet they'd be great with a smallish valve amp.
The problem area now is around the crossover frequency. According to the specs crossover frequency is 2k - however the tweeter is already overpowering the woofer at 1k. At this frequency the woofers output is still healthy and clean, the level has not dropped significantly from an octave below, but the tweeter is louder and to make matters worse it's exhibiting a "ringing" distortion artifact when playing a 1k sine wave. I wonder if this is the driver itself or the crossover? I'd say that subjectively from roughly 1k to just over 2k the output from the tweeter is (if anything) stronger than the upper treble registers - certainly there is no indication of any roll off below 2k
This all explains the harshness / unevenness in the upper mids. And I'm hoping it means there's room for improvement/tweaks.
I'm in two minds whether I need to look at / alter crossover frequency (probably just for tweeter) or whether there's an easier fix to tame this - First step is going to be pulling the crossover out and having a look - I'll post some photos.
The easy fix to my non-expert mind would just be a simple pad to bring sensitivity for both drivers to an equal point. But maybe there's a cleverer way to smooth the response given the subjective peak in the lower treble. I guess as standard the crossover is set-up to match overall sensitivity based on the boosted midbass response with the original port setup. Makes sense as originally they sounded balanced between (mid)bass and treble but with a hole in the middle. Although it seems counterintuitive to reduce the sensitivity of a horn loaded tweeter in a way - obviously it's been designed with high sensitivity in mind.
I did also wonder whether there was a way to tweak the physical properties of the horn to tame the output, e.g. lining it with wool felt or similar. But I suspect that would be very hit and miss.
Hi! The port based enclosure is a kind of resonant system, so we do expect some time to sound pressure to kick in. I'm not a super expert in this matter, but I understand that group delay reflects somehow this behaviour. As anything in speakers, if we keep something not desirable minimized, it's ok.
Sealed is for sure the best option, but you loose quite amount or bass, as you can see in the chart I've posted - around 4dB between 30 to 50Hz. At 30Hz compared to the long port solution. This is 2.5 in terms of power.
Comparing the difference in group delay (low tune versus sealed), it is only 6ms more in the long ported. Supposing the speaker I'm using as an example, of course.
Speaker's I've been building have around 12ms to 16ms at 30Hz and for me and other people that are using them it's fine.
You have to judge and decide what you loose and what you gain.
The difference from the original 2-port setup and the 1-port long is huge at 30Hz. It's around 12dB! This is 15 times in terms of power. After gaining this amount of bass, if you boost a bit more with more power, you can get a really decent frequency response for an indoor small room.
In terms of amp, valve amps normally don't offer too much power unless you build a huge and expensive device.
In your case, I'd go with a class AB or even a good class-D such as the TPA3255 (you can find good ready to use integrations such as from Aiyima and Fosi). With something between 100 and 150W you can push 6 to 10dB in the low end bass and get a cool indoor result. I've recommended this TPA3255 for a studio and they are very satisfied. Using a 48V/5A power supply, you can have 120W/channel @4ohm. There are also 48V/10A power supplies.
How much power does your Kenwood have? Just to have a baseline idea.
Crossover can do a lot. Starting in last year, I've built several speakers using a calibrated mic to measure the frequency/phase response as well as getting the actual impedance curves of each speaker. With this on hand, I've been using the XSim (crossover simulator) to build the crossovers.
The results are amazing compared to other speakers I've build in the past without following this new procedures and softwares.
So the right way to adjust crossovers is using this procedure.
But, if you don't want to take a deep dive on this matter (acquiring a mic, getting the software REW, XSIM etc), yes, you can make a lot of adjustments in the crossover and listen to the result (trial and error). In this case, some reference such as a headphone or another good speaker is valuable. You adjust by "ear".
I would start with padding - a simple in series resistor with the driver to start with.
Then you can modify the capacitors/inductors bit here and there to change the frequency cuts. Let's see what you have inside this box - if you can get the schematic, we can simulate it in the XSim.
Just pay attention to not make an adjustment that will lower the impedance below the original nominal in order to not cause problems to the amplifier.
If you take this way, wihout tools, it's worth to take a look on a post that AllenB (very knowledgeable and helpfull member of this forum) made for this purpose:
Here, I have no experience at all.
Thanks again! Amp is effectively temporary as I have access to better stuff but it's fine for testing - it's a very bog standard Japanese class AB integrated of about 40WPC. For my current application rated power isn't really an issue with these speakers as they're very efficient - would go loud with a small amp - albeit something with plenty of current on tap often helps bass performance IME.
I had a quick look at the crossovers - they look relatively complex so I haven't got my head around what's going on although I suspect that the multiple similar resistors and capacitors are probably just run in parallel to aid power handling - in other words probably less complicated than they look!
I have requested a schematic from Martin Audio - before I try to work out the circuit I'll wait to see if that arrives.
I had a quick look at the crossovers - they look relatively complex so I haven't got my head around what's going on although I suspect that the multiple similar resistors and capacitors are probably just run in parallel to aid power handling - in other words probably less complicated than they look!
I have requested a schematic from Martin Audio - before I try to work out the circuit I'll wait to see if that arrives.
