Hello guys
Long story so I will cut it so you at least feel my pain..18 months ago a purchased 2 bk electronics monoliths and I wasn't overly impressed so after watching many YouTube videos I decided to build 2 subs. So I purchased 2 dayton um18 22 and 2 sa1000 amps.
The boxes I made are
600mm wide
700mm high
700mm deep
External measurements
18mm x2 mdf all round so each panel is
36mm
Furniture foam inside on all sides
When I set it all up they sounded and measured exactly the same as monoliths. I knew this was impossible and I must have an issue. After four exhausting days of fault finding I found a audio enhancement setting on the TV but not in TV settings!! This setting was only visible when I went into the TV through my lap top!! Now the monoliths sound awesome 👌 and I wish I purchased two more at £1400
I'm now £1700 in with the dayton build and they don't sound know where near as good as the bk monoliths! They are punchy and lack extension below 30hz. Infact they only sound good and really loud from 27-40hz But I think they could come good if I add two passive rads to each box
Il be £2400 in by then!! What do you think guys? Are passives the answer? Or new boxes? I was hoping to build monsters but all I've done is put put a monster hole in my bank account!! I'm gutted 😢 😞
I've just ordered a Cambridge 2 channel amp aswell. It's getting out of hand guys! I want to get it right so I just enjoy it instead of obsessing. Big room 4 subs 1 in each corner.
Long story so I will cut it so you at least feel my pain..18 months ago a purchased 2 bk electronics monoliths and I wasn't overly impressed so after watching many YouTube videos I decided to build 2 subs. So I purchased 2 dayton um18 22 and 2 sa1000 amps.
The boxes I made are
600mm wide
700mm high
700mm deep
External measurements
18mm x2 mdf all round so each panel is
36mm
Furniture foam inside on all sides
When I set it all up they sounded and measured exactly the same as monoliths. I knew this was impossible and I must have an issue. After four exhausting days of fault finding I found a audio enhancement setting on the TV but not in TV settings!! This setting was only visible when I went into the TV through my lap top!! Now the monoliths sound awesome 👌 and I wish I purchased two more at £1400
I'm now £1700 in with the dayton build and they don't sound know where near as good as the bk monoliths! They are punchy and lack extension below 30hz. Infact they only sound good and really loud from 27-40hz But I think they could come good if I add two passive rads to each box
Il be £2400 in by then!! What do you think guys? Are passives the answer? Or new boxes? I was hoping to build monsters but all I've done is put put a monster hole in my bank account!! I'm gutted 😢 😞
I've just ordered a Cambridge 2 channel amp aswell. It's getting out of hand guys! I want to get it right so I just enjoy it instead of obsessing. Big room 4 subs 1 in each corner.
Attachments
“There’s a silver lining to every cloud” Anon.
“I've missed more than 9,000 shots in my career. I've lost almost 300 games. Twenty-six times, I've been trusted to take the game winning shot and missed. I've failed over and over and over again in my life. And that is why I succeed." Michael Jordan
“when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when’s you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely in your thoughts advanced to the state of Science...”Lord Kelvin
“You spent only £1700 in audio R&D?! Now it’s time to get some measurement equipment ” Thanh
“I've missed more than 9,000 shots in my career. I've lost almost 300 games. Twenty-six times, I've been trusted to take the game winning shot and missed. I've failed over and over and over again in my life. And that is why I succeed." Michael Jordan
“when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when’s you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely in your thoughts advanced to the state of Science...”Lord Kelvin
“You spent only £1700 in audio R&D?! Now it’s time to get some measurement equipment ” Thanh
I'm not an expert on this, and it's admittedly been quite some time since I dove into the subwoofer scene, but I do have UM18's and I do have some thoughts.
Where did you get the box dimensions? Are they sealed or ported?
Adding more subs should help to smooth out room response. To a certain extent the performance of one subwoofer in one specific location is far less important than how they perform as a single unit in the room. Are all 4 subwoofers pig tailing off of a single subwoofer output or does your receiver have multiple subwoofer outs? If you're running them all off of the same output I'm very confident you're going to have time alignment issues which is going to effect their performance as a single (4 subs combined) unit.
Assuming the problem isn't the settings on the amplifiers (phase/eq/etc, it could easily just be an improperly designed enclosure which is a relatively inexpensive fix.
Are the monolith's sealed or ported? It's a lot easier to get 4 subwoofers tuned to the same frequency to sound good together than it is mixing tuning frequencies and ported and sealed enclosures.
Once we better understand the problem we can help, but personally I think solving this problem is going to involve a umik and a mini-dsp of some kind.
Alternately, the brute force solution is move all of the speakers equidistant from the main listening position to "attempt" to circumvent time alignment issues. Let's say hypothetically that the UM18's are in a ported box... Plug the port with some socks and let them roll off to confirm that the problem isn't tuning. My UM18 subs play up past 300hz and all the way down 11hz with a little bass boost via the mini-dsp .
The other possibility is that what you're hearing from 27-40 is actually your room resonating, but again.. If you get the time alignment right, that will smooth out by having 4 subs.
Any way we slice this. Your problem can be made better with testing and modification. Maybe it's the enclosure, maybe it's the amp settings, maybe it's placement, maybe it's timing, maybe you have the wires plugged into the wrong inputs on the back, but it's fixable. Take a deep breath.
I have umic1 and mini dsp. I have done time alignment using a 25hz signal..thanks for your reply
I have pretty good (expensive) hp laptop. First it was impossible to use it for audio measuring because loop did not look right. Had hump in bass and crosstalk.
Then I noticed B&O logo. I started digging in the audio settings and found some stupid laptop sound enhancing mode was engaged. What a stupid thing.
All is good now.
Then I noticed B&O logo. I started digging in the audio settings and found some stupid laptop sound enhancing mode was engaged. What a stupid thing.
All is good now.
Great, you’re off to a good start.
I take it Youre doing an In-room measurement?
That is, at best, useless in subwoofer/woofer/midrange loudspeaker design, and at worse, misleading
You need to do a baffle diffraction compensated near-field measurement.
Have you heard of this terminology?
If not, you’re in for a treat:
Read on, friend!
http://audio.claub.net/software/FRD...curate In-Room Frequency Response to 10Hz.pdf
I have purchased a roll a of wadding to full fill the box. It's 20mm thick. Is this the correct stuff? I'm not buying anything again before asking you guys! I just get carried away. I'm now thinking it's too heavy and maybe I should of purchased light lose poly fill or ikea cushions as mentioned in a previous thread.. what are your thoughts guys. As it is I have lined the sides of the box with heavy cusion foam (yellow) stuff 50mm out of settes and it just too boomy
I don’t think that’s going to solve your problem. Since you still haven’t said, I’m going to assume it’s an appropriate sized sealed box. Set your amps to a completely flat setting. Do not use them for EQ at all. Run your sweeps, use rew to create the filters and apply the filters in the dsp program. Do not attempt to boost the bottom and the top, but instead cut where your current boost is. Then test again and post the results.
Thankyou for your reply. I have done that and I get a pretty flat response but I will do it again this evening and post it. I have been told that stuffing will smooth it out
So your problem is close to being solved now? Stuffing can certainly help that last 10%. I wouldn’t expect any miracles but I’m happy to hear that you’re getting closer.
I emailed dayton about this the other day
Even though I'm getting a flat response it doesn't sound good in reality. I think you may be right about the box being to big! I spoke to dayton about this and the possibility of putting two rads in each box. Il post the reply
To dayton
Hello guys
I have build two um18 22 subs in sealed boxes. Dimensions are
600mm wide
700mm high
700mm deep
External measurements
18mm x2 mdf all round so each panel is 36mm
I am powering them off two sa 1000 amplifiers. 1 sub 1amp x2
I was wondering if you could do me a performance graph with a 500w signal for
A. My build as is
B. If I add two of your 18inch passive radiators to each box.
I would do this myself if I could but I lack computer skills. I'm good with a trowel but computers are a no no.
It would be much appreciated if you could help me with this so I can make a decision on what to do next. They do sound fantastic but I'm looking for more low end extension without boosting on dsp. I don't really want to port them and risk ruining the boxes I've made.
Thankyou
Hello guys
I have build two um18 22 subs in sealed boxes. Dimensions are
600mm wide
700mm high
700mm deep
External measurements
18mm x2 mdf all round so each panel is 36mm
I am powering them off two sa 1000 amplifiers. 1 sub 1amp x2
I was wondering if you could do me a performance graph with a 500w signal for
A. My build as is
B. If I add two of your 18inch passive radiators to each box.
I would do this myself if I could but I lack computer skills. I'm good with a trowel but computers are a no no.
It would be much appreciated if you could help me with this so I can make a decision on what to do next. They do sound fantastic but I'm looking for more low end extension without boosting on dsp. I don't really want to port them and risk ruining the boxes I've made.
Thankyou
Below are the results in your request. The red line is the current setup, it models with an F3 of 27 Hz if there is no damping material in the box. And if there is a typical level of damping material then it raises that F3 to about 29 Hz. The yellow line is with two of the passive radiators and modeled with all the included disk weights attached. It needs all the added mass to model smoothly in this case. The F3 is 18 Hz, and it drops to 17 Hz with a typical level of damping material in the box. Neither model shows signs of over excursion so both are valid setups.
I would expect the passive setup will not just get lower but sound a bit boomy with that 3 dB rise in the response before the roll off. So, I would suggest adding a lot of damping material to the box in that setup to smooth out the low-end a bit. That way it would not sound quite as boomy at the lower end right before the roll-off. The blue line in the second image below is with the box heavily damped and it seems to model a bit nicer by taking that edge off. And it does not change the F3 by doing so in this case, still 17 Hz. So it would be worth taking the extra step.
It would appear that your box is more than twice as big as it should be. Can you try filling it with books? I’m kind of kidding. Radiators to my understanding are more helpful in designing a smaller box, but it’s probably more complicated than that. In all seriousness, maybe you can fill the cavity with something that will get the internal volume down to 4 cubic feet.
Should I port it? I just built the biggest boxes that would fill the corner of the room! I based it on a radiator self build that is on sound imports.I made it slightly bigger to account for the um18 instead of refrence sub and double walls instead of single. Il attach the link
