Odd low frequency dip, and a way to address it... any comments?

dkulmacz

Member
Thread Starter
Joined
Mar 4, 2020
Messages
29
Location
Detroit, MI
My AV System  
Preamp, Processor or Receiver
Onkyo TX-NR818
Front Speakers
Hsu
Center Channel Speaker
Hsu
Subwoofers
Hsu
I have a bedroom studio using a pair of Kali Audio IN-8 monitors and an SVS SB-1000 sealed subwoofer, powered by a MiniDSP HD unit. The room has a decent amount of DIY rockwool acoustic treatment; floor-to-ceiling 15" superchunk wedges in the front corners, 6" thick panels on the sidewalls at first reflection points, a few superchunk wedges here and there on floor/wall boundaries front and side, a 3" thick cloud mounted 3" below the ceiling. The room itself is 10' x 12' x 8'. I've done plenty of data gathering and adjustment using REW and the Mini DSP EQs.

The odd (perhaps) problem? The Kali monitors -- who can play pretty flat down to around 40 Hz per REW -- produce a severe dip at 109 Hz when playing. I assumed this was a room resonance, because 109 Hz is very close to 10' wavelength. However...... when I play the SVS subwoofer with no crossover, it produces a relatively flat response all the way up to 200 Hz. No sign at all of a dip at 109 Hz. The Kali monitors are set as close to the wall behind them as possible, they're toed in 30 degrees to point at the listening position, and the back corner is less than a centimeter away from the wall (at ear-height, with the center of the woofer cones 33" from the side walls). The SVS sub is also nearly flush against the back wall, on the floor, side-firing with the driver sitting at the room midpoint.

As a combined 3-way system, any setup with a "normal" crossover point (say, below 80 Hz) shows the 109 Hz dip in full force. But I've found that if I set the crossover point very high -- from 160 Hz up to 200 Hz -- then the 109 Hz dip disappears, since the subwoofer (which doesn't exhibit the dip) is providing the sound at those frequencies. Or at least, that's my interpretation.

Because the Kalis are so close to the back wall, I didn't think SBIR would be the problem. But since the frequency is very near the side-to-side dimension resonance, maybe it's that. Though I've tried moving the speakers sideways within practical limits, and it didn't seem to do a whole lot to eliminate the dip. Is it possible to have SBIR issues with the side walls? And if so, any ideas on how to address this?

Also, is setting the subwoofer crossover point high -- say, 180 Hz -- a viable strategy to fix this? I don't know if that is high enough to start messing with the stereo image and such. It seems to be a nice fix for an otherwise thorny problem.......
 

thothsong

Member
Joined
Jun 29, 2021
Messages
161
You're seeing the dip in which of these cases: a) single channel sweep, sub disconnected b) single channel sweep, sub connected c) dual channel sweep, sub disconnected d) dual channel sweep, sub connected? If you don't see it with a), then it sounds like phase cancellation.
 

dkulmacz

Member
Thread Starter
Joined
Mar 4, 2020
Messages
29
Location
Detroit, MI
My AV System  
Preamp, Processor or Receiver
Onkyo TX-NR818
Front Speakers
Hsu
Center Channel Speaker
Hsu
Subwoofers
Hsu
You're seeing the dip in which of these cases: a) single channel sweep, sub disconnected b) single channel sweep, sub connected c) dual channel sweep, sub disconnected d) dual channel sweep, sub connected? If you don't see it with a), then it sounds like phase cancellation.
Single channel sweep, no sub..... severe but wide dip
Double channel sweep, no sub..... very narrow severe dip (the worst)

Sub only sweep, no crossover..... wide shallow dip

Single channel sweep, +sub, 80 Hz crossover..... severe but wide dip
Double channel sweep, +sub, 80 Hz crossover.... very narrow severe dip

Single channel sweep, +sub, 200 Hz crossover.... wide shallow dip
Double channel sweep, +sub, 200 Hz crossover.... wide shallow dip

The "wide shallow dip" cases are wide (from maybe 80-120 Hz) and down around -10dB from the "average" bass response. The "narrow severe dip" cases are narrow (more like 100-115 Hz) and down -20dB or more. The "severe but wide dip" are shaped quite differently; they slope down steadily from 80 Hz to around 110 Hz, but still are down -20dB from the average. Data taken at my "optimal" listening position, on centerline and back about 5 1/2 feet from the front wall.

Note when I took data closer to the front wall, this 109 Hz dip problem was much worse; moving back almost to the center of the room helped it. It used to be a *very* narrow drop, right off the scale of the chart, in most cases.
 

thothsong

Member
Joined
Jun 29, 2021
Messages
161
Posting an mdat file of those measurements (using a timing ref) might be useful. One additional suggestion is to take a nearfield 0-degree measurement of a low frequency sweep of a single channel, no sub, to minimize room interaction, just to rule that out, but a dip with a single channel and no sub sounds like a room interaction, to me.
 

dkulmacz

Member
Thread Starter
Joined
Mar 4, 2020
Messages
29
Location
Detroit, MI
My AV System  
Preamp, Processor or Receiver
Onkyo TX-NR818
Front Speakers
Hsu
Center Channel Speaker
Hsu
Subwoofers
Hsu
Posting an mdat file of those measurements (using a timing ref) might be useful. One additional suggestion is to take a nearfield 0-degree measurement of a low frequency sweep of a single channel, no sub, to minimize room interaction, just to rule that out, but a dip with a single channel and no sub sounds like a room interaction, to me.
Hopefully these are all done correctly...... I'm not sure what the "0 degree measurement" means for the nearfield; I just moved the mic (omnidirectional from Dayton Audio) in front of the speaker, pointing towards it and upwards at a 45 degree angle.
 

Attachments

Last edited:

dkulmacz

Member
Thread Starter
Joined
Mar 4, 2020
Messages
29
Location
Detroit, MI
My AV System  
Preamp, Processor or Receiver
Onkyo TX-NR818
Front Speakers
Hsu
Center Channel Speaker
Hsu
Subwoofers
Hsu
And here is a diagram showing the layout of the room and position of the speakers, FYI. The monitors lay on their sides with the tweeter/Midrange on the outside. The sub is pointing sideways with the driver at the center of the room. Data taken at the yellow asterisk point.

53922
 

thothsong

Member
Joined
Jun 29, 2021
Messages
161
I'm no expert, but it looks to me like you've simply got a null at your LP around 108 Hz when the sub isn't active, due to room geometry. Try measuring L and L+R about 2.5 ft left and right of your LP. The sub looks to have a similar problem around 88 Hz; I'd try testing the sub at different positions in the room, if you can. BTW, it looks like you also have a bad L+R interaction between 8 kHz and 14 kHz.
 

ddude003

Senior Member
Joined
Aug 13, 2017
Messages
899
Location
Somewhere Northeast of Kansas City Missouri
My AV System  
Preamp, Processor or Receiver
PrimaLuna Dialogue Premium TubePre (2 channel+sub)
Main Amp
McIntosh MC152 SS Amp (2 channel)
Additional Amp
Yamaha RX-A850 Pro (the other 5 channels lol)
Computer Audio
MacBook Pro, Custom i7 7700k De-lid 2xAsus1080ti GFX build, Audirvana+, LiquidSonics, SoX
DAC
Chord Electronics Ltd. Qutest
Universal / Blu-ray / CD Player
Sony UBP-X700 /M Ultra HD 4K HDR
Front Speakers
Martin Logan ElectroMotion ESL
Center Channel Speaker
Martin Logan Motion C2
Surround Speakers
Martin Logan Motion 4
Surround Back Speakers
Martin Logan Motion 4 (yes, another set of these)
Subwoofers
Martin Logan Dynamo 700
Other Speakers or Equipment
Cifte 12AU7 NOS & Genalex Gold Lion Tubes in Pre
Video Display Device
Samsung The Premiere LSP7T UST Laser Projector
Screen
Elite Screens Aeon CLR3 0.8 Gain 103-inch
Remote Control
PrimaLuna & Lumin iApp
Streaming Equipment
Netgear Nighthawk S8000 Streaming Switch, Lumin U1 Mini Streamer/Transport
Streaming Subscriptions
Roon & QoBuz Studio Premier, Amazon Prime & Netflix
Other Equipment
ThrowRug, SaddleBlankets, WideBand & BaseTraps...
I would be tempted to move the listening position back a few feet towards 1/3rd from the back wall... Place your sub there in the new listening position and crawl around the room to "see" where the sweet spot is for the sub to be placed in its forward firing position... I would also place your monitors in their upright position, or if your are going to mess with them try upside down... I have to wonder what their Klipple spin-o-rams look like upright vs on their side...
 

dkulmacz

Member
Thread Starter
Joined
Mar 4, 2020
Messages
29
Location
Detroit, MI
My AV System  
Preamp, Processor or Receiver
Onkyo TX-NR818
Front Speakers
Hsu
Center Channel Speaker
Hsu
Subwoofers
Hsu
Thanks for the feedback!

Well, maybe I'll start moving some furniture and try the old "sub in chair, crawl on floor" method to find the best spot for it, since moving the sub seems to be a common idea. I'll also take some added data at other positions before I do that.

BTW, it looks like you also have a bad L+R interaction between 8 kHz and 14 kHz.
Can you tell me what typically causes this? Is it room related? Something I can fix, or try to fix?

I would also place your monitors in their upright position, or if your are going to mess with them try upside down... I have to wonder what their Klipple spin-o-rams look like upright vs on their side...
Can you tell me why? I understand many monitors can't be tipped, but these (Kali IN-8) are supposed to be OK with it, because they are 3-ways with coaxial tweeter and midrange driver (so no phase shift), and without asymmetric waveguides (no weird dispersion). I found the bass response to be better when I had the monitors closer together, so I figured tipping them let me keep the woofers closer while still pushing the midrange/tweeters further apart for better separation. (Plus I designed and built custom speaker stands out of oak slabs, dense poly foam, and concrete blocks after deciding to tip the speakers and there's no modifying them to make them shorter.... I'm very attached to them for some reason, probably all the hours I spent making them!)

try upside down...
EDIT: I guess I could do this and just raise the stands up a bit, and still have the tweeters/midrange at ear level. That would put the woofers very close to the halfway point between floor and ceiling.... is that bad? Good?

I have to wonder what their Klipple spin-o-rams look like upright vs on their side...
So I found this article.... does this have what you're looking for? It says the data was taken using Klippel’s Near-Field Scanner and it mentions SPINORAMA.

 
Last edited:

thothsong

Member
Joined
Jun 29, 2021
Messages
161
Can you tell me what typically causes this? Is it room related? Something I can fix, or try to fix?
The Left channel alone looks OK. You should measure the Right channel alone to verify that it's OK. If it is, then the problem is their interaction with each other, but I'm not knowledgeable enough to explain, and I don't know what you can do about it.
 

ddude003

Senior Member
Joined
Aug 13, 2017
Messages
899
Location
Somewhere Northeast of Kansas City Missouri
My AV System  
Preamp, Processor or Receiver
PrimaLuna Dialogue Premium TubePre (2 channel+sub)
Main Amp
McIntosh MC152 SS Amp (2 channel)
Additional Amp
Yamaha RX-A850 Pro (the other 5 channels lol)
Computer Audio
MacBook Pro, Custom i7 7700k De-lid 2xAsus1080ti GFX build, Audirvana+, LiquidSonics, SoX
DAC
Chord Electronics Ltd. Qutest
Universal / Blu-ray / CD Player
Sony UBP-X700 /M Ultra HD 4K HDR
Front Speakers
Martin Logan ElectroMotion ESL
Center Channel Speaker
Martin Logan Motion C2
Surround Speakers
Martin Logan Motion 4
Surround Back Speakers
Martin Logan Motion 4 (yes, another set of these)
Subwoofers
Martin Logan Dynamo 700
Other Speakers or Equipment
Cifte 12AU7 NOS & Genalex Gold Lion Tubes in Pre
Video Display Device
Samsung The Premiere LSP7T UST Laser Projector
Screen
Elite Screens Aeon CLR3 0.8 Gain 103-inch
Remote Control
PrimaLuna & Lumin iApp
Streaming Equipment
Netgear Nighthawk S8000 Streaming Switch, Lumin U1 Mini Streamer/Transport
Streaming Subscriptions
Roon & QoBuz Studio Premier, Amazon Prime & Netflix
Other Equipment
ThrowRug, SaddleBlankets, WideBand & BaseTraps...
As I will be traveling today, I won't have much time to look at your charts and compare them with the spin-o-rama charts that are presented on the ASR article you pointed out... Maybe you could check and see if they match up... Being on their side may cause different interactions with themselves and/or the room... It's just an easy thing to try standing them upright... Another thing to try is to move your crossover below 80Hz and see what that does... If the speakers reach down to 40Hz, a 50Hz or 55Hz crossover might be an interesting area to try...
 

dkulmacz

Member
Thread Starter
Joined
Mar 4, 2020
Messages
29
Location
Detroit, MI
My AV System  
Preamp, Processor or Receiver
Onkyo TX-NR818
Front Speakers
Hsu
Center Channel Speaker
Hsu
Subwoofers
Hsu
The sub looks to have a similar problem around 88 Hz
88 Hz is roughly 12.75 feet wavelength..... the room is 12 feet long, with about half of the back wall actually an open closet two feet deep, so 14 feet.

So I have one dip at around 109 Hz or 10 feet (room width) and one dip at 88 Hz or 12.75 feet (roughly room length). There doesn't seem to be any dip at 140 Hz (about 8 feet, ceiling height), but there is one at about 164 Hz, or 7 feet. Sounds like I simply have unavoidable room effects.
 

thothsong

Member
Joined
Jun 29, 2021
Messages
161
It's worth measuring at a few points further behind your current LP, to see if moving the LP farther back will help any of those dips. And still worth seeing if a sub move will help.
 

ddude003

Senior Member
Joined
Aug 13, 2017
Messages
899
Location
Somewhere Northeast of Kansas City Missouri
My AV System  
Preamp, Processor or Receiver
PrimaLuna Dialogue Premium TubePre (2 channel+sub)
Main Amp
McIntosh MC152 SS Amp (2 channel)
Additional Amp
Yamaha RX-A850 Pro (the other 5 channels lol)
Computer Audio
MacBook Pro, Custom i7 7700k De-lid 2xAsus1080ti GFX build, Audirvana+, LiquidSonics, SoX
DAC
Chord Electronics Ltd. Qutest
Universal / Blu-ray / CD Player
Sony UBP-X700 /M Ultra HD 4K HDR
Front Speakers
Martin Logan ElectroMotion ESL
Center Channel Speaker
Martin Logan Motion C2
Surround Speakers
Martin Logan Motion 4
Surround Back Speakers
Martin Logan Motion 4 (yes, another set of these)
Subwoofers
Martin Logan Dynamo 700
Other Speakers or Equipment
Cifte 12AU7 NOS & Genalex Gold Lion Tubes in Pre
Video Display Device
Samsung The Premiere LSP7T UST Laser Projector
Screen
Elite Screens Aeon CLR3 0.8 Gain 103-inch
Remote Control
PrimaLuna & Lumin iApp
Streaming Equipment
Netgear Nighthawk S8000 Streaming Switch, Lumin U1 Mini Streamer/Transport
Streaming Subscriptions
Roon & QoBuz Studio Premier, Amazon Prime & Netflix
Other Equipment
ThrowRug, SaddleBlankets, WideBand & BaseTraps...

dkulmacz

Member
Thread Starter
Joined
Mar 4, 2020
Messages
29
Location
Detroit, MI
My AV System  
Preamp, Processor or Receiver
Onkyo TX-NR818
Front Speakers
Hsu
Center Channel Speaker
Hsu
Subwoofers
Hsu
So.... I've done some more measurements and made some changes.

In the end, I guess this wasn't "odd" at all.... it seems like it was just room modes as would be expected.

I tried most of the suggestions made here, except for moving the subwoofer. I tried different crossover settings, and settled on using 50 Hz since the monitors easily reproduce down to 40 Hz and the measurements looked good. I measured at different listening positions all the way back to about 1/3 from the back wall; ultimately, this shifted frequencies around in both the high and low registers, but didn't really solve any problems (I also took data to the sides, but it just confirmed that I was dealing with room modes). I tried setting the speakers upright (and also raising the measurement mic, since this moved the tweeters up about 9 inches), and it didn't seem to make that much of a difference overall. Finally, I figured I would try flipping the monitors from their original orientation, e.g., with the tweeters on the inside instead of on the outside. This seems to have made a big difference; in fact, it's my new default setup I'm going forward with.

Moving the tweeters/midrange inwards changed the shape of my equilateral triangle setup, so I could bring the listening position in closer to the front wall (and closer to my desk, an added benefit). This setup pretty much eliminated the severe dips in the bass response, replacing them with a much smoother wider drop maxing at around -7 dB. I also found that toeing the speakers outwards a few degrees so they converge at a point a bit behind my head really minimizes the high frequency crosstalk issues in the 10K-14K Hz range; the only real issue I have left is a dip at around 950 Hz which I think is due to desk reflections.

As of now, after using REW to calculate an EQ curve, I'm very happy with the results I'm getting. This is why I'm not bothering with the effort of trying to move the sub; honestly I don't have a lot of flexibility due to the room size and setup, so I doubt it would be worth it (at best I'd just find the perfect spot that I can't realistically use).

Thanks everyone for your advice and support!
 

Attachments

kevinzoe

Member
Joined
Jun 10, 2022
Messages
27
My AV System  
Preamp, Processor or Receiver
PrimaLuna DiaLogue Premium preamp
Main Amp
PS Audio BHK Signature 250 stereo amp
Additional Amp
Valve Amplification Company 30/30 Renaissance
Computer Audio
JRiver
DAC
exaSound e48 (8 channels)
Front Speakers
Acoustic Zen Crescendos
Subwoofers
Pair of Rythmik F15's
Other Equipment
Cables by: TEO Audio, Cardas and AudioSensibility
dkulmacz,
To help you put your nulls into perspective, not all nulls are worth "fixing" because they may land on what IS NOT a musical note.
The table below lists the frequency of say notes on a piano ( but other instruments would play the same thing.) Looking to see if your nulls of 88, 109, 140, and 164Hz are actual notes . . . and it appears that all are not musical notes although some are within 1hz of a note. Likely best for deep narrow nulls that affect fewer notes than shallower and broader nulls. You might experiment with adjusting the crossover of the sub and/or mains to see if a null can be moved to a non-note. Good luck with it all . . .
53992
 

thothsong

Member
Joined
Jun 29, 2021
Messages
161
the only real issue I have left is a dip at around 950 Hz which I think is due to desk reflections
FWIW, between the two most recent measurements you posted, I think I'd pick the Upright one, as the 600 Hz to 3 kHz range would be more important to me than above 5 kHz.
 

dkulmacz

Member
Thread Starter
Joined
Mar 4, 2020
Messages
29
Location
Detroit, MI
My AV System  
Preamp, Processor or Receiver
Onkyo TX-NR818
Front Speakers
Hsu
Center Channel Speaker
Hsu
Subwoofers
Hsu
FWIW, between the two most recent measurements you posted, I think I'd pick the Upright one, as the 600 Hz to 3 kHz range would be more important to me than above 5 kHz.
I think a lot of the improvement in that area is because both the midrange/tweeter pair and the measurement mic were raised about 8 inches higher, which minimizes the desk reflections that cause the dip. If I adjusted the stand heights to put the tweeter back at ear level, I think the improvement you see would disappear.

Anyway.... I did some playing with the internal EQ settings on the Kali Monitors (I had them set to "sideways on console" and switched them to "flat") and physically aligned the speakers, and here's my final set of measurements. Overall -- especially in comparison to any earlier setups I had managed with the same equipment in the same room -- I think it looks pretty good and sounds great, and I'm quite happy with it.
 

Attachments

ddude003

Senior Member
Joined
Aug 13, 2017
Messages
899
Location
Somewhere Northeast of Kansas City Missouri
My AV System  
Preamp, Processor or Receiver
PrimaLuna Dialogue Premium TubePre (2 channel+sub)
Main Amp
McIntosh MC152 SS Amp (2 channel)
Additional Amp
Yamaha RX-A850 Pro (the other 5 channels lol)
Computer Audio
MacBook Pro, Custom i7 7700k De-lid 2xAsus1080ti GFX build, Audirvana+, LiquidSonics, SoX
DAC
Chord Electronics Ltd. Qutest
Universal / Blu-ray / CD Player
Sony UBP-X700 /M Ultra HD 4K HDR
Front Speakers
Martin Logan ElectroMotion ESL
Center Channel Speaker
Martin Logan Motion C2
Surround Speakers
Martin Logan Motion 4
Surround Back Speakers
Martin Logan Motion 4 (yes, another set of these)
Subwoofers
Martin Logan Dynamo 700
Other Speakers or Equipment
Cifte 12AU7 NOS & Genalex Gold Lion Tubes in Pre
Video Display Device
Samsung The Premiere LSP7T UST Laser Projector
Screen
Elite Screens Aeon CLR3 0.8 Gain 103-inch
Remote Control
PrimaLuna & Lumin iApp
Streaming Equipment
Netgear Nighthawk S8000 Streaming Switch, Lumin U1 Mini Streamer/Transport
Streaming Subscriptions
Roon & QoBuz Studio Premier, Amazon Prime & Netflix
Other Equipment
ThrowRug, SaddleBlankets, WideBand & BaseTraps...
Glad you got it dialed in @dkulmacz... :T It would depend on what kind of music you mix/listen to as for your preference of importance of frequency ranges to focus on...

You didn't say much about your mixing kit... Do you happen to have access to a convolution engine? :bigsmile:
 
Last edited:

dkulmacz

Member
Thread Starter
Joined
Mar 4, 2020
Messages
29
Location
Detroit, MI
My AV System  
Preamp, Processor or Receiver
Onkyo TX-NR818
Front Speakers
Hsu
Center Channel Speaker
Hsu
Subwoofers
Hsu
Do you happen to have access to a convolution engine? :bigsmile:
What, pray tell, is that?

I have a reverb plugin for Ableton that I believe uses convolution to mimic specific reverb spaces, but I'm guessing that's not what you are talking about. I think I've heard of processors that take an IR of your room and "undo" the response using convolution.... is that it? If there's software available for the MiniDSP 2x4 HD that does that I'd definitely check it out.

As far as I understand the rest of the question, I drive the speakers/sub with a MiniDSP 2x4 HD processor, using their standard software to provide crossover and EQ. That unit is driven by a Scarlett 3rd Gen 18i8 audio interface, which has things like mics, Bass DI, guitar DI, a drum machine, and a bunch of synths running into it in addition to the computer output.
 

ddude003

Senior Member
Joined
Aug 13, 2017
Messages
899
Location
Somewhere Northeast of Kansas City Missouri
My AV System  
Preamp, Processor or Receiver
PrimaLuna Dialogue Premium TubePre (2 channel+sub)
Main Amp
McIntosh MC152 SS Amp (2 channel)
Additional Amp
Yamaha RX-A850 Pro (the other 5 channels lol)
Computer Audio
MacBook Pro, Custom i7 7700k De-lid 2xAsus1080ti GFX build, Audirvana+, LiquidSonics, SoX
DAC
Chord Electronics Ltd. Qutest
Universal / Blu-ray / CD Player
Sony UBP-X700 /M Ultra HD 4K HDR
Front Speakers
Martin Logan ElectroMotion ESL
Center Channel Speaker
Martin Logan Motion C2
Surround Speakers
Martin Logan Motion 4
Surround Back Speakers
Martin Logan Motion 4 (yes, another set of these)
Subwoofers
Martin Logan Dynamo 700
Other Speakers or Equipment
Cifte 12AU7 NOS & Genalex Gold Lion Tubes in Pre
Video Display Device
Samsung The Premiere LSP7T UST Laser Projector
Screen
Elite Screens Aeon CLR3 0.8 Gain 103-inch
Remote Control
PrimaLuna & Lumin iApp
Streaming Equipment
Netgear Nighthawk S8000 Streaming Switch, Lumin U1 Mini Streamer/Transport
Streaming Subscriptions
Roon & QoBuz Studio Premier, Amazon Prime & Netflix
Other Equipment
ThrowRug, SaddleBlankets, WideBand & BaseTraps...
Sounds like a nice kit for a one man show... And yes there are several stand alone convolution engines/apps/systems that allow you to mimic specific "spaces" or almost anything you can sample, like speaker cabinets, amplifiers and other old analogue FX boxes you can think of... Your reverb plugin might even allow you to load your own .wav files... And those .wav files could undo/invert the response as a form of Room EQ... Have a look at this screen shot... https://www.avnirvana.com/threads/v5-20-10-early-access.10787/post-81649... And over here... https://community.roonlabs.com/t/creating-convolution-files-for-roon-in-the-new-room-eq-wizard-rew-with-inversion/208776... This method works for me with both Roon and with my LiquidSonics plugin...
 
Last edited:

dkulmacz

Member
Thread Starter
Joined
Mar 4, 2020
Messages
29
Location
Detroit, MI
My AV System  
Preamp, Processor or Receiver
Onkyo TX-NR818
Front Speakers
Hsu
Center Channel Speaker
Hsu
Subwoofers
Hsu
Do you know how a convolution engine with a correction IR compares to using FIR filters? The 2x4 HD supports FIR filters (but not convolution) and there are tutorials on the MiniDSP site about how to calculate the FIR filter coefficients in REW, and overall a lot of it seems similar to the process in the roonlabs video.
 

ddude003

Senior Member
Joined
Aug 13, 2017
Messages
899
Location
Somewhere Northeast of Kansas City Missouri
My AV System  
Preamp, Processor or Receiver
PrimaLuna Dialogue Premium TubePre (2 channel+sub)
Main Amp
McIntosh MC152 SS Amp (2 channel)
Additional Amp
Yamaha RX-A850 Pro (the other 5 channels lol)
Computer Audio
MacBook Pro, Custom i7 7700k De-lid 2xAsus1080ti GFX build, Audirvana+, LiquidSonics, SoX
DAC
Chord Electronics Ltd. Qutest
Universal / Blu-ray / CD Player
Sony UBP-X700 /M Ultra HD 4K HDR
Front Speakers
Martin Logan ElectroMotion ESL
Center Channel Speaker
Martin Logan Motion C2
Surround Speakers
Martin Logan Motion 4
Surround Back Speakers
Martin Logan Motion 4 (yes, another set of these)
Subwoofers
Martin Logan Dynamo 700
Other Speakers or Equipment
Cifte 12AU7 NOS & Genalex Gold Lion Tubes in Pre
Video Display Device
Samsung The Premiere LSP7T UST Laser Projector
Screen
Elite Screens Aeon CLR3 0.8 Gain 103-inch
Remote Control
PrimaLuna & Lumin iApp
Streaming Equipment
Netgear Nighthawk S8000 Streaming Switch, Lumin U1 Mini Streamer/Transport
Streaming Subscriptions
Roon & QoBuz Studio Premier, Amazon Prime & Netflix
Other Equipment
ThrowRug, SaddleBlankets, WideBand & BaseTraps...
I am not sure what you are asking here... I don't have any experience with the MiniDSP products... I believe that both resolution and accuracy are higher using state of the art software convolution/convolvers compared to most _affordable_ hardware DSP solutions... We aren't talking about COTS signals systems like Mercury Systems... I think the author of the Hang Loose Convolver said that it is like having one EQ "slider" per 0.7 Hz... Roon is showing 50k taps for a 48kHz x 24bit convolution, 108k taps for a 96kHz x 24bit and 192kHz x 24bit for 217k taps convolution with my IR.wav room correction, two channel stereo... How does that compare with the MiniDSP??? Digging... Digging... Referring to the MiniDSP User Manual 7.5.1 FIR filtering overview... "The 2x4 HD can compute a total of 4096 taps. These taps can be distributed as you wish across the four output channels, with the limitation that each output channel must have 6 or more taps and can have no more than 2048 taps."...
 
Last edited:

Anatoliy Gavrilov

Registered
Joined
Apr 27, 2019
Messages
9
My AV System  
Main Amp
SE - 6С33С - 6П15П
Additional Amp
Technics SE-M100
Universal / Blu-ray / CD Player
Sony CDP-557 ESD
Front Speakers
Seas 3-way
54244


Всем привет! Измерения надо проводить в 1/3 октавы - такая избирательность слуха, и это доказано. Для амплитудной характеристики нужна фазочастотная характеристика, иначе эквалайзером можно много дров наломать.
На итоговом графике видны проблемы с фазой на 850 и 1400 Гц — это плохо, потому что фазовые сдвиги лежат в зоне максимальной чувствительности слуха.
 

dkulmacz

Member
Thread Starter
Joined
Mar 4, 2020
Messages
29
Location
Detroit, MI
My AV System  
Preamp, Processor or Receiver
Onkyo TX-NR818
Front Speakers
Hsu
Center Channel Speaker
Hsu
Subwoofers
Hsu
View attachment 54244

Всем привет! Измерения надо проводить в 1/3 октавы - такая избирательность слуха, и это доказано. Для амплитудной характеристики нужна фазочастотная характеристика, иначе эквалайзером можно много дров наломать.
На итоговом графике видны проблемы с фазой на 850 и 1400 Гц — это плохо, потому что фазовые сдвиги лежат в зоне максимальной чувствительности слуха.
Thanks you for your response (I had to use Google Translate, but I understood it.)

I am confused by phase issues; I was considering trying to use the MiniDSP 2x4 HD's 2048 tap to create a single FIR filter exclusively to address a phase issue but don't know if this is possible, and how to go about designing the proper filter (examples seem to focus on magnitude not phase).
 
Top Bottom