Parametric equaliser on Raspberry Pi

Going Grey Now

Active Member
Would anyone have any first hand experience of running a PE on a Pi and be able to help with some basic settings?
I have a nasty bass hump/resonance at around 40hz and I am trying to tweak this out - sadly without success.
I have read various comments/guides etc but whatever I try just seems to completely mess up the overall sound.
The standard graphic equaliser doesn’t give me the control that I need.
Thanks
 

raptor

Well-known Member
Hi can i ask what speakers you have ?
 

raptor

Well-known Member
Ok i don't know the speakers at all sorry so all i can say is what i found on my own journey with my Neat speakers, i had the same problem as you so as i was running Volumio i played with the in built equaliser and things did change but not that much so next was to decoupled the speakers from the floor but i sill had boom.
So after reading loads about this problem i went with foam plugs for the speakers reflex port and this fixed the problem for me.
I must admit the last thing i wanted to do was pop foam into the port but it did the job and the bass is sill present and faster with no boom.
I understand this is a very complex problem and every system and room is different so a bit of trial and error is the best i can say.
 

Going Grey Now

Active Member
Ok i don't know the speakers at all sorry so all i can say is what i found on my own journey with my Neat speakers, i had the same problem as you so as i was running Volumio i played with the in built equaliser and things did change but not that much so next was to decoupled the speakers from the floor but i sill had boom.
So after reading loads about this problem i went with foam plugs for the speakers reflex port and this fixed the problem for me.
I must admit the last thing i wanted to do was pop foam into the port but it did the job and the bass is sill present and faster with no boom.
I understand this is a very complex problem and every system and room is different so a bit of trial and error is the best i can say.
Thanks.
I have zero experience of foam plugs although the thought had crossed my mind in case all else failed.
My speakers are so old that they either never had bungs supplied, or they’ve been lost over the years.
Did your speakers have bungs or did you have to come up with your own solution? If the latter, do you need to have bungs specially made (with thoughts to size/foam density) or is it a case of wedging any old bit of foam into the port and playing round until it sounds OK?
 

TheHighFlyingBirds

Distinguished Member
What software are you running on the pi? If picoreplayer there is a 10 band equaliser which you have to enable in settings. Although for me enabling it seems to cause distortion on some albums.
 

Going Grey Now

Active Member
I’m currently running Moode and before that, Volumio.
Moode has a multi band standard EQ which isn’t giving me the flexibility I need. From memory, it gives about 8? Bands; the lowest about 32hz, then 65hz or so and my “hump/boom” seems to be right in the middle.
The inputs I need for the 4 band Parametric EQ seem straightforward, but when I try them (40hz, bandwidth 4 and minus say 12db gain), it doesn’t produce the required result with the bass hump still being far too pronounced. I’ve played around with the bandwidth and (negative) gain numbers to no avail.
I could really do with some advice from someone who has used the parametric EQ and who can advise me what it is that I’m doing wrong. Alternatively, an “idiots” guide for the parametric EQ (which, if I understand correctly, is an industry standard EQ/plug in rather than having been designed by Moode).
By the way, I think this is a fantastic piece of software for the RPi.
 

Monster900

Active Member
I’m currently running Moode and before that, Volumio.
Moode has a multi band standard EQ which isn’t giving me the flexibility I need. From memory, it gives about 8? Bands; the lowest about 32hz, then 65hz or so and my “hump/boom” seems to be right in the middle.
The inputs I need for the 4 band Parametric EQ seem straightforward, but when I try them (40hz, bandwidth 4 and minus say 12db gain), it doesn’t produce the required result with the bass hump still being far too pronounced. I’ve played around with the bandwidth and (negative) gain numbers to no avail.
I could really do with some advice from someone who has used the parametric EQ and who can advise me what it is that I’m doing wrong. Alternatively, an “idiots” guide for the parametric EQ (which, if I understand correctly, is an industry standard EQ/plug in rather than having been designed by Moode).
By the way, I think this is a fantastic piece of software for the RPi.

I'm not sure if this helps, but problems with bass balance can be caused by speaker placement. I started a thread here as was worried that my new speakers would need to be placed a long way into the room to work well (not a problem as it turned out). Many contributors offered some good advice on how to correctly test speaker placement. It may be worth a look to see if your boomy bass problem can be solved just by adjusting your speaker placement.
 

TheHighFlyingBirds

Distinguished Member
Thanks.
I have zero experience of foam plugs although the thought had crossed my mind in case all else failed.
My speakers are so old that they either never had bungs supplied, or they’ve been lost over the years.
Did your speakers have bungs or did you have to come up with your own solution? If the latter, do you need to have bungs specially made (with thoughts to size/foam density) or is it a case of wedging any old bit of foam into the port and playing round until it sounds OK?
Think as a test you can use socks rolled up. Sure I've someone on here who has suggested it. Worth a try.
 

raptor

Well-known Member
Thanks.
I have zero experience of foam plugs although the thought had crossed my mind in case all else failed.
My speakers are so old that they either never had bungs supplied, or they’ve been lost over the years.
Did your speakers have bungs or did you have to come up with your own solution? If the latter, do you need to have bungs specially made (with thoughts to size/foam density) or is it a case of wedging any old bit of foam into the port and playing round until it sounds OK?
I was lucky and found some from an old set of speakers and the fit was just right,did the same trick to my wife's hifi in the kitchen (got lot's of brownie points too).

My mane system is in the living room with all the compromise that go with this sort of room so my speakers are not in the best position at all but it's that or nothing and for me it worked very well.
Do let us all know how you get on.
 

Going Grey Now

Active Member
I'm not sure if this helps, but problems with bass balance can be caused by speaker placement. I started a thread here as was worried that my new speakers would need to be placed a long way into the room to work well (not a problem as it turned out). Many contributors offered some good advice on how to correctly test speaker placement. It may be worth a look to see if your boomy bass problem can be solved just by adjusting your speaker placement.
many thanks. I’ve just had a read through of your thread.
My speakers are approx 2.1 meters apart and slightly toe-d in. I have tried them at 10/20/30/50/70cm from the back wall and apart from a very modest (but insufficient) decrease to the bass thump at 70 cm, nothing seems to work. Not only that but at 70cm off the back wall the placement looks ridiculous and even if it had sorted the problem, would have been impractical.
I have downloaded one of those basic sound analysers to my phone and as far as I can be sure the ‘thump” is at around 40hz. Allowing for the fact that the analyser hasn’t an exact scale, this ties in quite well with the low bass extension of the speakers - claimed as 47hz +/- 3db.
Things are bad enough that recently my wife was watching TV in the bedroom (above the lounge) and said that the whole room shook on certain notes (frequencies).
I think I’m going to have to try the foam bung solution after all.
 

Going Grey Now

Active Member
I was lucky and found some from an old set of speakers and the fit was just right,did the same trick to my wife's hifi in the kitchen (got lot's of brownie points too).

My mane system is in the living room with all the compromise that go with this sort of room so my speakers are not in the best position at all but it's that or nothing and for me it worked very well.
Do let us all know how you get on.
Thanks.
Have since posted a reply to @Monster900 as per above.
I think I’ll try rolled up socks first and if that works, go the foam route. I do need to be careful, though. Only last week I was doing something with the spiked feet and with the bass port on the underside of the speaker, dropped a nut. Guess where it ended up! I was lucky to be able to retrieve it without it getting wedged behind some of the internal sound insulation stuff.
 

gibbsy

Moderator
I think I’m going to have to try the foam bung solution after all.
KEF supply all their speakers with a two piece foam bung which is very handy. You can also fine tune the port by pushing and pulling the foam into position. I use the half port bung with my speakers being 30cm from a rear wall. Using foam can be very effective in taming boundary issues.
 

Going Grey Now

Active Member
KEF supply all their speakers with a two piece foam bung which is very handy. You can also fine tune the port by pushing and pulling the foam into position. I use the half port bung with my speakers being 30cm from a rear wall. Using foam can be very effective in taming boundary issues.
many thanks.
I tried the foam bung solution this afternoon, though not having anything purpose made, I used some foam off cuts I had lying around. They went in rather tight & the foam was very dense.
I seem to have partially ruined the overall SQ as I’m now missing some of the rich/warm tones that I had before.
Sadly, it’s not simply a case of me quickly removing and then replacing the foam to confirm the difference in SQ. My bass ports exit on the underside of the speaker and the only way to get at them is to unscrew the plinths. Start to finish on both speakers is close on a 10 minute job.
I think I may have to concentrate on the ParametricEQ unless I can sort out a way of cutting out less bass with purpose made bungs.
 

gibbsy

Moderator
many thanks.
I tried the foam bung solution this afternoon, though not having anything purpose made, I used some foam off cuts I had lying around. They went in rather tight & the foam was very dense.
I seem to have partially ruined the overall SQ as I’m now missing some of the rich/warm tones that I had before.
Sadly, it’s not simply a case of me quickly removing and then replacing the foam to confirm the difference in SQ. My bass ports exit on the underside of the speaker and the only way to get at them is to unscrew the plinths. Start to finish on both speakers is close on a 10 minute job.
I think I may have to concentrate on the ParametricEQ unless I can sort out a way of cutting out less bass with purpose made bungs.
Bit tricky. KEFs are rear ported which makes fine tuning much easier.
 

raptor

Well-known Member
many thanks.
I tried the foam bung solution this afternoon, though not having anything purpose made, I used some foam off cuts I had lying around. They went in rather tight & the foam was very dense.
I seem to have partially ruined the overall SQ as I’m now missing some of the rich/warm tones that I had before.
Sadly, it’s not simply a case of me quickly removing and then replacing the foam to confirm the difference in SQ. My bass ports exit on the underside of the speaker and the only way to get at them is to unscrew the plinths. Start to finish on both speakers is close on a 10 minute job.
I think I may have to concentrate on the ParametricEQ unless I can sort out a way of cutting out less bass with purpose made bungs.
So did it lower the boom ? if so you know your on to something,i did note on my speakers by moving the foam further in/out will change the sound.

The foam i have is not very dense so that might be the problem you are getting (like blocking the port fully) not what you want.

I get the thing about how difficult it is to get at the port on your speakers but this is a cheep fix and it's just time you are spending.
 

Going Grey Now

Active Member
So did it lower the boom ? if so you know your on to something,i did note on my speakers by moving the foam further in/out will change the sound.

The foam i have is not very dense so that might be the problem you are getting (like blocking the port fully) not what you want.

I get the thing about how difficult it is to get at the port on your speakers but this is a cheep fix and it's just time you are spending.
The foam fixed the boom but did not improve the overall sound. I strongly suspect it was because I used off cuts which were very dense. it basically ruined the overall sound, making it quite “thin”.
At the moment, I’m back playing with the parametric EQ in Moode which is proving something of a challenge. To start with I had to watch several videos to work out what bandwidth/Q was all about and it’s just as well I did because in no way did I find it intuitive. Having downloaded one of those sound analyser apps onto my IPAD, I’ve identified a thump/hump/boom at 43-47hz but in attempting to negate this, I seem to be adversely affecting the overall sound again!
Sadly, I’m starting to come round to the view that it’s mainly room related and that my lounge just doesn’t play nicely with sound in this frequency range. But I am far from being an expert in these matters.
Given that I simply cannot live with this issue long term, I am reluctantly thinking that I will have to go one of two ways. Either change my speakers— and go for quality stand mounts which don’t reach down below 50hz, or invest in some sort of DSP type device (but that looks pricey).
Before I do anything, though, I’ve going to reconnect a CD player and play my “reference track” and compare it to the same FLAC file on my Pi. My logic is that if I can ensure matched amp volume then if the boom is there when listening to the CD track then it’s speaker/room related. If not, the it could be Pi/DAC Hat related.
 

gvh

Active Member
Don't know how computer savvy you are but the next step is room correction. Enter the world of minidsp.
I used to have Castle Severn 2 and the bass was way too much. Had to remove the spacers at the bottom to close them off and drop the bass

Or buy a used anthem amp with arc. Amazing
 

Going Grey Now

Active Member
Don't know how computer savvy you are but the next step is room correction. Enter the world of minidsp.
I used to have Castle Severn 2 and the bass was way too much. Had to remove the spacers at the bottom to close them off and drop the bass

Or buy a used anthem amp with arc. Amazing
thank you. delighted to hear from a fellow member who has/had the same speakers. Having very little first hand exper3ince of different speakers, my decision to buy the Severns was not made with any prior knowledge of the Castle range.
I’m really interested to hear that you removed the spacers. Mine have 2 installed and wasn’t sure if reducing to 1 would make a difference. I hadn’t even thought about removing them completely.
From your experience do you think I should persevere with the Severns and add room correction? If I go this route, I really wouldn’t know where to start though!
Do you mind me asking what speakers you moved on to and how they compare to the Severns?
I don’t mind spending some money but want to get away from always thinking I’ve got to upgrade.
 

gvh

Active Member
Lie them on their side and look underneath..... I ended up closing them up completely. It's only bass after all.

From your description you are getting a room resonance.

I saved my pennies and finally went for 5 Monitor Audio Silver off an Anthem MRX 500. Only a slight upgrade...
Older Anthems come up fairly often and plenty on that auction site. Just make sure it comes with the microphone and software. The kit is now old and needs adaptors to work with a modern laptop, so it is still not plain sailing to get into room correction at any decent price if you are not technical
 

Going Grey Now

Active Member
Lie them on their side and look underneath..... I ended up closing them up completely. It's only bass after all.

From your description you are getting a room resonance.
,,,, ,,,,
exactly the conclusion I’m coming to which presumably means that even if I change the speakers, then anything with a low end in the mid 40s is likely to potentially cause me similar problems.

I’ve seen various comments re minidsp and wonder if this is something that I should start looking at seriously.

As a matter of interest, did you find that with both spacers removed and no gap between the bottom of the speker and the plinth, that your Severns improved to the point that you could be happy with them?

Thanks
 

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