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SB Acoustics SB20FRPC30-8 based desktop project

a. yes, you will need a simple low-shelf to reach to F3 45Hz. Without any DSP your F9 will be 45Hz
b. in a 26L ported box your F6 will be 47Hz, see:

View attachment 328892

for this you will need a vent with diameter = 65mm, length = 135mm
I would rather go for the sealed but you will decide :)

c. Well, you will then need to remove the vent and seal the hole to become airtight (not just fill the vent hole)
Excellent, just perfect! Thank you so much for this.
Is there a way to design a passive low shelf to install in the cabinets instead of using dsp? If so, can you advise on the design?
 
Excellent, just perfect! Thank you so much for this.
Is there a way to design a passive low shelf to install in the cabinets instead of using dsp? If so, can you advise on the design?

Yes, but I am not an expert in that, sorry (only in DSP)
 
I am not using miniDSP. My DSP is a Windows 11 PC with Jriver and various VST plugins
Wow I would love to know what hardware I need cause I have multi channel hypex amps and windows computer. I just searched j River is a software but how to connect 4 cannel amps to compuetre for dsp
 
Wow I would love to know what hardware I need cause I have multi channel hypex amps and windows computer. I just searched j River is a software but how to connect 4 cannel amps to compuetre for dsp
There are a number of ways to make it happen:

- My setup is rather 'unorthodox': I have three Sabaj A30A amps that are FDAs (Full Digital Amp) so one should use their digital inputs only. For that I am using a miniDSP U-DIO8 that is NOT a DSP device but it is only for converting USB to 4 SPDIF outputs (so it is essentially a multichannel digital-digital converter)
Then I connect my three A30As to this device via digital coax
Alternatively you could also use an RME Digiface USB for the same purpose - I happen to have one for sale :)
Another alternative here is to connect multiple stereo DACs to the U-DIO8 or to the RME Digiface USB and then connect power amps to the DACs respectively

- Another - more conventional - way is to use a multichannel DAC, like the Topping DM7 (which unfortunately is no longer in production) or Okto DAC8 Pro or MOTU M4 or MOTU Ultralite mk5, etc.
In that case you could just connect the amps to the outputs of said multichannel DAC

In any case you can have up to 8 output channels only and it is not possible to have Atmos channels - these are the limitations of using a PC as the source

On the other hand you will have state-of-the-art DSP capabilities and flexibility with Jriver + the literally endless number of VST plugins
And you will have SINAD and other measurable quality indicators waaaaay above any AVR....
 
I am not using miniDSP. My DSP is a Windows 11 PC with Jriver and various VST plugins
This is very right approach, in my opinion. If I may, I would recommend you even better way - to take look at Ekio software. It has very nice feature that you may upload REW measurement in *.txt curve. Then you may work on filters and VISUALLY see results of applied filters. Interestingly measurement in REW made later, after applying corrections, perfectly match predicted by Ekio curve. See screenshots - 1st is REW measurement of SB20frpc30-8 in 60 liters bass reflex with NO correction (just curve from REW imported). Second shows several of filters applied to flatten down the response. You can see on the screen result of each filter LIVE. In my opinion it's awersome. Later, once I have filters done I manually copy (peak dB, Q, freq) to Jriver equalizer - this part of the workflow is already exactly as you do. The differance is I have, let's name it, "measurement and correction guidnance (or better call it navigation?)" and don't need to measure after each change. Just overall measure after bunch of corrections to confirm if all went well. Another differance is I use heavily optimizes Windows Server 2012 not Win 11. I have only 29 processes running in bacground, while with Win11 I never managed go below 114 - 98 processes. It's debateble does it hurt or not, but at least I have "good feeling" :) :) that I am having audio dedicated computer :)
 

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This is very right approach, in my opinion. If I may, I would recommend you even better way - to take look at Ekio software. It has very nice feature that you may upload REW measurement in *.txt curve. Then you may work on filters and VISUALLY see results of applied filters. Interestingly measurement in REW made later, after applying corrections, perfectly match predicted by Ekio curve. See screenshots - 1st is REW measurement of SB20frpc30-8 in 60 liters bass reflex with NO correction (just curve from REW imported). Second shows several of filters applied to flatten down the response. You can see on the screen result of each filter LIVE. In my opinion it's awersome. Later, once I have filters done I manually copy (peak dB, Q, freq) to Jriver equalizer - this part of the workflow is already exactly as you do. The differance is I have, let's name it, "measurement and correction guidnance (or better call it navigation?)" and don't need to measure after each change. Just overall measure after bunch of corrections to confirm if all went well. Another differance is I use heavily optimizes Windows Server 2012 not Win 11. I have only 29 processes running in bacground, while with Win11 I never managed go below 114 - 98 processes. It's debateble does it hurt or not, but at least I have "good feeling" :) :) that I am having audio dedicated computer :)

This sounds great! btw. did you know that you can do the same in REW? You can simulate the PEQ filters in real-time and not only you can see their impact on the frequency curve but also on all the other curves

I have stopped using manual PEQ filters, I am now using Dirac Live (3.10.3) to optimize both my systems
I do use some pre-Dirac and post-Dirac filters (such as crossover and shelves) though

1722788392921.png
 
No, I didn't knew REW can design filters. Does work like I can prepare filters at "got what you see" REW curve modification, and then copy them to any good parametric equalizer?
Is the Dirac Live a VST plugin?
 
No, I didn't knew REW can design filters. Does work like I can prepare filters at "got what you see" REW curve modification, and then copy them to any good parametric equalizer?
Is the Dirac Live a VST plugin?

You need to go to the EQ menu, there you can either manually apply filters or make REW generate them automatically fitting the freq. curve on a target curve that you define
You can then generate the resulting curves to compare them with your original and you can also export the filters in a convolution wav file or just manually type them into a PEQ like Jriver. After applying the PEQ filters and doing a verification measurement the results will match REW's simulation curves >95% at least
 
Last year I did a project based on Markaudio CHR120 drivers in my home office

Then this year when I did my rear speaker project using the SB20FRPC30-8 drivers I really got astonished by these drivers so I have decided to replace my CHR120 desktop system with the SBs

I already have the SB drivers, they arrived yesterday:

View attachment 283422

Since I have already sold my CHR120 drivers the plan is to re-use their now empty sealed cabinets:

View attachment 283423


X-max limited max input power will be 45W:

View attachment 283424

At 45W I will get 85.6dB at 1 meter at 24Hz (=91.6dB for stereo + I will have considerable room gain too)
Listening distance will be approx. 70cm

View attachment 283425

Group delay:

View attachment 283427


Impedance:

View attachment 283428


I will keep on posting pictures and later on some measurements and videos
I will use Dirac Live 3.x for corrections
@ppataki - may I get your advice please? In this project you use 11 liters box (that left after some other project to my understanding). But you also published in the other thread project with larger box.
I have box (very nicely finished legacy speakers box) that has 15,8 liters internal volume. Do you think it is good enough to use with SB20FRPC30-8? With modest 5 -10W power in room of 30sq meters
 
@ppataki - may I get your advice please? In this project you use 11 liters box (that left after some other project to my understanding). But you also published in the other thread project with larger box.
I have box (very nicely finished legacy speakers box) that has 15,8 liters internal volume. Do you think it is good enough to use with SB20FRPC30-8? With modest 5 -10W power in room of 30sq meters

Well, in a 16 liter sealed box you will need 30W to drive these speakers to xmax
If you have 5-10W of power and you want to apply some DSP in the low-end too then I am afraid that will not be enough. But it is worth trying, worst case scenario is that you will need to buy a nice Topping amp ;)
 
Well, in a 16 liter sealed box you will need 30W to drive these speakers to xmax
If you have 5-10W of power and you want to apply some DSP in the low-end too then I am afraid that will not be enough. But it is worth trying, worst case scenario is that you will need to buy a nice Topping amp ;)
OK, let me ask other way round: I have couple of amps on the shelf, from 5W to 300W. Then I can grab whatever I want. BUT except of power - do you anticipate/can tell from experiance any OTHER drawbacks of using 16 liter closed cabinet? Issues with bottom freq, whatever else? I assume, since smallest you have used were 11 liters and you liked it all is fixable in DSP. Is it safe assumption? I ask because sometimes it happens that speaker corrected in DSP/measuring mic to +/- 2dB totally flat (so in measurements, theroretically, perfect) sounds ugly in real life. How it is with SB Acoustic and small couple litres enclosure?
 
OK, let me ask other way round: I have couple of amps on the shelf, from 5W to 300W. Then I can grab whatever I want. BUT except of power - do you anticipate/can tell from experiance any OTHER drawbacks of using 16 liter closed cabinet? Issues with bottom freq, whatever else? I assume, since smallest you have used were 11 liters and you liked it all is fixable in DSP. Is it safe assumption? I ask because sometimes it happens that speaker corrected in DSP/measuring mic to +/- 2dB totally flat (so in measurements, theroretically, perfect) sounds ugly in real life. How it is with SB Acoustic and small couple litres enclosure?
For me there was absolutely no problem with the 11 liter box
I just had to apply more boost (low-shelf) in the low-end - which requires adequate amp power
But if you have it, I would anticipate no issues whatsoever in a 16 liter box
 
For me there was absolutely no problem with the 11 liter box
I just had to apply more boost (low-shelf) in the low-end - which requires adequate amp power
But if you have it, I would anticipate no issues whatsoever in a 16 liter box
Lovely!! One more question, if I may - cabinet I have (ready made) has relatively narrow front wall (250mm) that will make SB Acoustic SB20FRPC30-8 fill (in L-R direction) practically entire wall from egde to edge (as the speaker is 218mm). The box is tall (460mm) so UP-DOWN front wall is not an issue. To my knowledge in closed cabinets it doesn't play important role for bass reproduction (I know for bass reflex it does).
So this L-R narrow size shoud not be an issue - can you confirm or deny thought above please?
 
Lovely!! One more question, if I may - cabinet I have (ready made) has relatively narrow front wall (250mm) that will make SB Acoustic SB20FRPC30-8 fill (in L-R direction) practically entire wall from egde to edge (as the speaker is 218mm). The box is tall (460mm) so UP-DOWN front wall is not an issue. To my knowledge in closed cabinets it doesn't play important role for bass reproduction (I know for bass reflex it does).
So this L-R narrow size shoud not be an issue - can you confirm or deny thought above please?
There shall be no issues with that at all
I have designed/built closed cabinet speakers where the driver went wall-to-wall and had no issues whatsoever
 
There shall be no issues with that at all
I have designed/built closed cabinet speakers where the driver went wall-to-wall and had no issues whatsoever
Fantastic, thank you for all your knowledge/experiance. Much appreciated. One more question - what is the name of this software? So far I am using Basta and WinISD, that produces surprisingly consistent results (especially true for bass reflex calculations). BUT it is always good to have 3rd software to cross-check :)

1723116080000.png
 
Fantastic, thank you for all your knowledge/experiance. Much appreciated. One more question - what is the name of this software? So far I am using Basta and WinISD, that produces surprisingly consistent results (especially true for bass reflex calculations). BUT it is always good to have 3rd software to cross-check :)

View attachment 385311
You are welcome!
This is BassBox Pro
 
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