There is more T25B + M74B + Purifi+Hypex+DSP speakers: https://www.presentdayproduction.co...-10-studio-monitor-pair-50-deposit-pre-launch
Thank you all for the comments. In particular thanks to @Kwesi , @tktran303 , @Juhazi i, and @piotr z for showing some inspiring ideas.
Along with the requirement that the system use the M74A-6 driver, there are a few more constraints which are important in the early conceptual phase. One is that the speaker will be aesthetically pleasing and will fit into my living space. In practice this means it will have a polished wood finish. Another requirement is that it shall weigh no more than 50 lb, or it will be made up of modules where each module weighs no more than 50 lb.
The last constraint is to allow me to switch between speakers frequently. My current main system consists of (per side) a woofer box with a 12” SB34NRX75-6 driver, a speaker stand with a Hypex 3 channel FA253 built in, and replaceable midrange-tweeter top units. I have two top units I cycle between. The first uses a Satori MW16TX midwoofer and a Satori TW29TXN-B tweeter, housed in a rectangular cabinet. The second uses a Purifi PTT6.5M04-NFA midrange and a Satori TW29BNWG waveguide tweeter, with the tweeter mounted in a freestanding waveguide enclosure. In both cases, the crossover from the top unit to the woofer boxes is at 200 Hz. Switching between the two top units is relatively easy and fast, and I do this every few months. When I am not using a speaker I store it upstairs, and I want to be able to move things around without the help of a neighbor.
I made this speaker below several years ago, an Avalon-like tower speaker with 2x8” woofers and Hypex FA123 DSP filtering and amplification. The final speaker sounded quite good, but was about 80 lb. I rarely use it because it is too difficult to get it up and down the stairs and into listening position.
Another advantage to a modular approach is that I am not locked-in to a particular woofer system. I have a concept for woofers which I will discuss in a future post, but I want to leave open the possibility of changing woofer cabinets as part of a future experimentations or upgrades... inspired by @DonVK. On the other hand, a modular architecture is more challenging to make aesthetically attractive, so I need to be mindful of this during the conceptual phase.
j.
Along with the requirement that the system use the M74A-6 driver, there are a few more constraints which are important in the early conceptual phase. One is that the speaker will be aesthetically pleasing and will fit into my living space. In practice this means it will have a polished wood finish. Another requirement is that it shall weigh no more than 50 lb, or it will be made up of modules where each module weighs no more than 50 lb.
The last constraint is to allow me to switch between speakers frequently. My current main system consists of (per side) a woofer box with a 12” SB34NRX75-6 driver, a speaker stand with a Hypex 3 channel FA253 built in, and replaceable midrange-tweeter top units. I have two top units I cycle between. The first uses a Satori MW16TX midwoofer and a Satori TW29TXN-B tweeter, housed in a rectangular cabinet. The second uses a Purifi PTT6.5M04-NFA midrange and a Satori TW29BNWG waveguide tweeter, with the tweeter mounted in a freestanding waveguide enclosure. In both cases, the crossover from the top unit to the woofer boxes is at 200 Hz. Switching between the two top units is relatively easy and fast, and I do this every few months. When I am not using a speaker I store it upstairs, and I want to be able to move things around without the help of a neighbor.
I made this speaker below several years ago, an Avalon-like tower speaker with 2x8” woofers and Hypex FA123 DSP filtering and amplification. The final speaker sounded quite good, but was about 80 lb. I rarely use it because it is too difficult to get it up and down the stairs and into listening position.
Another advantage to a modular approach is that I am not locked-in to a particular woofer system. I have a concept for woofers which I will discuss in a future post, but I want to leave open the possibility of changing woofer cabinets as part of a future experimentations or upgrades... inspired by @DonVK. On the other hand, a modular architecture is more challenging to make aesthetically attractive, so I need to be mindful of this during the conceptual phase.
j.
Yes, I also get acceptable results for a midrange driver in a rectangular baffle. But I run into difficulties with tweeters. If the tweeter has a diffraction hump (meaning on-axis gain) in the octave above or below the crossover, it will show up in the power response. I have found it is best to keep the tweeter diffraction hump smaller than 1.5 dB. The most effective way to do this is minimizing the flat baffle area around the tweeter.
Offsetting the drivers can be very useful when optimizing the on-axis response. It is possible to find some point on a rectangular baffle where all the edge diffractions balance themselves out such that the on-axis response is flat and appears diffraction-free. However, the diffraction effects are still there, but they are masked because the many peaks and nulls from various edges are cancelling themselves out on that one particular angle. A truly low-diffraction baffle has minimal diffraction effects when viewed from any horizontal angle, +/- 90 degrees. In my opinion, this can't be achieved with a sharp edged baffle. If we want to optimize both the on-axis response and the power response, I believe the best approach is either a waveguide tweeter in a well rounded low diffraction baffle, or a flat-faced tweeter in a well rounded baffle of minimal area. [edit - or a very wide baffle which effectively becomes an infinite baffle in the tweeters range)]
I agree they look fantastic... the spec says it weighs 90 kg (198 lb), so this size of cabinet is out of the question for me. I would need 3 people in my shop just to build it.
At this point I am strongly inclined to a stand-alone small trapezoidal enclosure for the M74A and tweeter.
I would love to build and own a clone of the very impressive Sonus Faber strad... but it just will not work in my living space.
j.
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It doesn't make sense to make separate boxes, as there is only one enclosure for midbas. If You don't make your box high, then You will have to make it more bulky to get the volume. Result will be roughly same weight and a lot of complications.
I’m not sure I agree. Separate boxes are preferable for a practical building/moving perspective, from a room modes/acoustics perspective and perhaps also on a resonance/damping perspective.
The only reason I see for a single big box is from a commercial perspective. It certainly makes it more impressive and thus perhaps a way to upsell to the consumer who is looking for a boutique/luxury good. A 3-way + subwoofer has virtually all the benefits of a 4 way, but that latter is certainly more impressive in size and pricing.
The informed buyer engineer acoustician studio owner would likely buy the former, the “tell me what to buy” investment banker perhaps might buy the latter. Of course, as DIYers, we are free to do as we please, and curiosity kills the cat, so some of us have built oversized speakers 5-6’ tall, 2 man lift/‘needs piano mover’ speakers to satisfy that curiosity. 🤪😂🙈
@hifijim
Will you be removing the faceplate of the tweeter?
My next speaker will be something like this:
The bottom section will have dual opposed woofers to
a) increase output whilst maintaining ‘acceptable proportion’ and
b) reduce cabinet vibrations/needs for massive overbracing/lighten the speaker)
c) neo motors to reduce offset the weight of having 3-4 woofers per box)
The top section will responsible for playing above Schroeder frequency (MT or coaxial)
For any requirements of 16-120Hz at higher SPL, I will deploy separate subwoofers.
The only reason I see for a single big box is from a commercial perspective. It certainly makes it more impressive and thus perhaps a way to upsell to the consumer who is looking for a boutique/luxury good. A 3-way + subwoofer has virtually all the benefits of a 4 way, but that latter is certainly more impressive in size and pricing.
The informed buyer engineer acoustician studio owner would likely buy the former, the “tell me what to buy” investment banker perhaps might buy the latter. Of course, as DIYers, we are free to do as we please, and curiosity kills the cat, so some of us have built oversized speakers 5-6’ tall, 2 man lift/‘needs piano mover’ speakers to satisfy that curiosity. 🤪😂🙈
@hifijim
Will you be removing the faceplate of the tweeter?
My next speaker will be something like this:
The bottom section will have dual opposed woofers to
a) increase output whilst maintaining ‘acceptable proportion’ and
b) reduce cabinet vibrations/needs for massive overbracing/lighten the speaker)
c) neo motors to reduce offset the weight of having 3-4 woofers per box)
The top section will responsible for playing above Schroeder frequency (MT or coaxial)
For any requirements of 16-120Hz at higher SPL, I will deploy separate subwoofers.
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@tktran303
Depends on situation. With mid being M74 with it's own enclosure there's need for only one box, so in order to split it, one would have to join them with some kind of large diameter pipe. Only other solution in such case is using two smaller midwoofers, and then one can build 2 boxes with smaller volumes.
Depends on situation. With mid being M74 with it's own enclosure there's need for only one box, so in order to split it, one would have to join them with some kind of large diameter pipe. Only other solution in such case is using two smaller midwoofers, and then one can build 2 boxes with smaller volumes.
@hifijim , great looking dome midrange choice. I'm a fan of domes and the trapezoid baffle profiles that follow the driver width. I did a number of BEM sims on various shapes and these help to generate good polars.
My dome-trapz version is still in garage experiment finish. I'm looking forward to how you construct yours, I need inspiration to finish mine. 🙂
My dome-trapz version is still in garage experiment finish. I'm looking forward to how you construct yours, I need inspiration to finish mine. 🙂
Jim, will you make a 3-way that will be highpassed with subs - or will you use the SB34 up to Bliesma M74?
I read that the new speaker must sit on the pole you have, is this correct? Then you can swap it to 2-ways when you want a change...
A floorstander that weighs less than 90lbs would not be High Performance...
🤔
I read that the new speaker must sit on the pole you have, is this correct? Then you can swap it to 2-ways when you want a change...
A floorstander that weighs less than 90lbs would not be High Performance...
🤔
When I tested a trapezoidal cabinet a few years back I built a test cabinet instead of trying to model it. When I measured the results I discovered the shape actually created an ugly mess of diffractions. I then taped some scrap MDF to the sides to turn the test baffle into a rectangle and much my and some folks on this forum the edge diffractions improved. So I scraped the trapezoid and built standard rectangular baffles with chamfers. They weren't as stylish but vastly easier to construct.
Tweeter options are still being explored, and I will need to make polar measurements of the midrange driver installed in a prototype trapezoid baffle in order to select the right tweeter option.
I will not be using the existing SB34NRX75-6 woofer cabinets up to 500 Hz to meet the M74A. The Bliesma M74A should be crossed no lower than 500 Hz second order. Early in the conceptual phase I struggled with how to handle the range from 30 Hz to 500 Hz. My existing bass cabinets work extremely well up to 200 Hz, but I have never been satisfied with the sound when crossed higher than that. I have experimented with a 300 Hz crossover, and I found the result to have less clarity, less detail, and a slightly muffled sound. So I knew that running these woofers/cabinets up to 500 Hz was not going to work.
This project will be a 3-channel active system... not 4 channels. I will not be using the SB34NRX75-6 woofer cabinets as subs. I have 3 channels of hypex DSP amplification, and I have to make it work with just those 3 channels, spanning from 30 Hz to 20k. So realistically, that means crossovers at about 500 Hz and 3.5k.
At this point I am considering a pair of 10" woofers, vertically stacked, with the M74A+tweeter trapezoid mounted on top. The two woofers would each have their own cabinet. I will try to post a sketch of this later today, perhaps.
@mtidge - - your cautions about a trapezoid baffle are interesting. I am going to make a prototype, and if I get the kind of result you are speaking of, I of course will abandon the idea... thanks !
j.
This may be of interest if you'd not already seen it https://heissmann-acoustics.de/en/kantendiffraktion-sekundaerschallquellen-treiberanordnun/
The "wide baffle" option e.g. Grimm LS1, looks quite nice to my eyes.
The "wide baffle" option e.g. Grimm LS1, looks quite nice to my eyes.
Ok, twin 10" (sealed) does sound HP! Lots of reasonably priced options too
Split tower is smart, you don't need to make the speaker too light. FA253 is easy to fit in the woofer cab's backside.
http://www.troelsgravesen.dk/Purifi-6661.htm
Split tower is smart, you don't need to make the speaker too light. FA253 is easy to fit in the woofer cab's backside.
http://www.troelsgravesen.dk/Purifi-6661.htm
Something like this: @Juhazi - yes you are speculating in the same direction...
It is challenging to pull off this configuration without it looking like an alien robot, but I have some ideas to soften the look and add some elegance.
For woofers, I am leaning towards the Dayton RSS265HF-8. It is not new, it is not trendy, and it is not sexy, but it has the right features I am looking for. It has an aluminum cone with a first mode resonance of about 2k, so it will remain pistonic up to 1000 Hz+. It has a well ventilated modern motor with Faraday shorting rings. It has a lot of Xmax and Vd, in fact a pair of them have 90% more Vd than the current SB34. The T/S parameters allow it to work well in a small sealed box of 25 - 30 liters with Linkwitz Transform EQ.
Sensitivity is on the low side at 84 dB/2.83 V, but with a pair of them in parallel, I get 90 dB sensitivity into 4 Ohm. Still not great, but acceptable.
So far, it appears to be one of the better options.
It is challenging to pull off this configuration without it looking like an alien robot, but I have some ideas to soften the look and add some elegance.
For woofers, I am leaning towards the Dayton RSS265HF-8. It is not new, it is not trendy, and it is not sexy, but it has the right features I am looking for. It has an aluminum cone with a first mode resonance of about 2k, so it will remain pistonic up to 1000 Hz+. It has a well ventilated modern motor with Faraday shorting rings. It has a lot of Xmax and Vd, in fact a pair of them have 90% more Vd than the current SB34. The T/S parameters allow it to work well in a small sealed box of 25 - 30 liters with Linkwitz Transform EQ.
Sensitivity is on the low side at 84 dB/2.83 V, but with a pair of them in parallel, I get 90 dB sensitivity into 4 Ohm. Still not great, but acceptable.
So far, it appears to be one of the better options.
If I was building this I think I would look at dual 8 inch woofers so the cabinet would lose the alien robot look. I think the RS225P-8A would work really well or the RS225P-8 if you have to have a metal cone. They both look flat from 100 to 1k and breakup above 2.5k. You would have 12 sq in less than a 12 inch woofer with sensitivities in the low 90's.
I was waiting to see what your plans were and was going to recommend those. My big build for 2025 will use to dual RSS315s sealed.
I can confirm that this old Dayton 10" sub works well in a sealed 1.3cf box with DSP. No problem getting flat response to <30Hz at high volume (>100 dB) with a pair in a good size room (roughly 4000cf), powered by 300W each.
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I find it useful to setout the design goals for a speaker.
Max SPL
Frequency range
Dispersion Angle.
Distortion
For my last build this was
108 dB
90 deg
0.1% approximately at moderate listening levels.
Distortion comes down to driver selection, low frequency limit for each driver and
usually I have to buy an assortment of drivers, do the testing, and send back the
losers.
The Max SPL can be calculated for the low frequency limit expected of each driver.
For example
So all of these drivers will provide 108 dB at Xmax with these lower frequency limits.
The desired dispersion angle can be used to find the upper limit for each driver.
I approximated this using the cone diameter.
So very wide dispersion can be had up to 840 Hz with the 10" woofer. This does not
include the effect of a waveguide that could be used on a midrange or tweeter.
As there is only the woofer box to build, it is interesting to find a box shape and size that
has it's first internal resonant mode well above the operating range of the woofer.
This favors woofers that require a small sealed volume and a cabinet with no
dimension that is much longer than the others.
I created a metric of woofer displacement volume divided by sealed box volume
to rank woofers. A good choice has large displacement for a small required box volume.
I think several Dayton woofers do well in this regard. I also found the SB and Scanspeak
discovery subwoofers do well.
The cabinet internal resonance modes can be calculated using the HornResp software.
Experimentation with that found the half cube shaped box with the woofer mounted
centered on the square face has the highest first resonant mode frequency. With the
boxes I showed in my earlier post this was around 800 Hz for the 10 inch woofer in a
40 liter box. A smaller volume would be required for a sealed box. This gives the crossover
sufficient range to roll off the signal before the first resonant mode is encounters. I
used an LR4th order on the woofer to achieve good results with no apparent box
sounds.
I attached the spreadsheet I used to calculate many of the results show above.
Maybe some of you will find it useful.
Max SPL
Frequency range
Dispersion Angle.
Distortion
For my last build this was
108 dB
90 deg
0.1% approximately at moderate listening levels.
Distortion comes down to driver selection, low frequency limit for each driver and
usually I have to buy an assortment of drivers, do the testing, and send back the
losers.
The Max SPL can be calculated for the low frequency limit expected of each driver.
For example
| Xmax | Freq Low Limit | N drivers | SPL at F low | Cone area cm^2 | |
| NE265W-08 10" | 9.4 mm | 40 Hz | 2 | 108 dB | 326 |
| sb-acoustics-sb26cdc | 0.5 | 2000 | 1 | 110.2 | 6.2 |
| Bliesma 3" Dome | 1.2 | 485 | 1 | 108 dB | 34.3 |
So all of these drivers will provide 108 dB at Xmax with these lower frequency limits.
The desired dispersion angle can be used to find the upper limit for each driver.
I approximated this using the cone diameter.
| Cone Diameter [inch] Calc from S | Cone Diameter cm | Frequency 45 deg dispersion | Frequency 90 degree dispersion |
| 8.0 | 20.4 | 1,681 | 841 |
| 1.1 | 2.8 | 12,208 | 6,104 |
| 2.6 | 6.6 | 5,194 | 2,597 |
So very wide dispersion can be had up to 840 Hz with the 10" woofer. This does not
include the effect of a waveguide that could be used on a midrange or tweeter.
As there is only the woofer box to build, it is interesting to find a box shape and size that
has it's first internal resonant mode well above the operating range of the woofer.
This favors woofers that require a small sealed volume and a cabinet with no
dimension that is much longer than the others.
I created a metric of woofer displacement volume divided by sealed box volume
to rank woofers. A good choice has large displacement for a small required box volume.
I think several Dayton woofers do well in this regard. I also found the SB and Scanspeak
discovery subwoofers do well.
The cabinet internal resonance modes can be calculated using the HornResp software.
Experimentation with that found the half cube shaped box with the woofer mounted
centered on the square face has the highest first resonant mode frequency. With the
boxes I showed in my earlier post this was around 800 Hz for the 10 inch woofer in a
40 liter box. A smaller volume would be required for a sealed box. This gives the crossover
sufficient range to roll off the signal before the first resonant mode is encounters. I
used an LR4th order on the woofer to achieve good results with no apparent box
sounds.
I attached the spreadsheet I used to calculate many of the results show above.
Maybe some of you will find it useful.
Last edited:
Jim, I thought you said you were doing dual opposed woofers for this next build. Above I see 2 woofers firing forward. You could use a quad of 4 ohm woofers per side to get that done.
FWIW, the RSS woofers are STILL some of my favorites in their bass capabilities. They are just incredible at the job they do.
FWIW, the RSS woofers are STILL some of my favorites in their bass capabilities. They are just incredible at the job they do.