Yet Another Four Dayton Audio Ultimax UM18-22 18" Sealed Build

the rolloff is *really* steep, if this is the amp then there is no way that is a natural rolloff

personally I would not lash out 00s on amps until I knew it really was the amp but then I have a bunch of random amps in the house already so maybe you have to buy an amp in order to find that out :)

do you have another amp handy? any old thing will do as you don't need much power. Some cheap class AB thing is fine, just something that will typically have wide bandwidth. If you do then measure it powering the subs and compare the response. You may need to reduce the level of course to not stress the amp (depending on what it is).

I guess wiring might be a challenge mind you but then you'll need to solve that anyway if you do get some inukes in
 
the rolloff is *really* steep, if this is the amp then there is no way that is a natural rolloff

personally I would not lash out 00s on amps until I knew it really was the amp but then I have a bunch of random amps in the house already so maybe you have to buy an amp in order to find that out :)

do you have another amp handy? any old thing will do as you don't need much power. Some cheap class AB thing is fine, just something that will typically have wide bandwidth. If you do then measure it powering the subs and compare the response. You may need to reduce the level of course to not stress the amp (depending on what it is).

I guess wiring might be a challenge mind you but then you'll need to solve that anyway if you do get some inukes in

Sounds like a good idea Matt, I do have a Behringer NX3000 powering one of my BOSS platforms, would that work?

If so like you said I need to work out a way of getting the speaker cable from the amp to the driver which is going to be difficult without drilling a hole in the cabinet.

I know I am going to have to do this anyway if I am going the external amp route but was going to drill the hole where the plate amp currently is but that obviously is not an option right now.

I suppose I could get a piece of MDF cut to the same size as the plate map & screw it to the cabinet using the same holes I used for the plate amp.

I can then drill the hole for the speaker cable in the "scrap" piece of MDF without worrying about damaging the cabinet any more than I already have :facepalm:

I guess it helps if I can seal the hole up as mush as possible?
 
Apologies if it has been covered previously but have you tried measuring the electrical output of your amp with simple voltmeter?

I know it won't be completely accurate but it might give you an idea. This is what I got when I measured mine at a given MV setting.

Hz Volts
60 4.7
50 6.6
40 5.7
30 14.3
20 27.6
10 35.7
5 20
 
Apologies if it has been covered previously but have you tried measuring the electrical output of your amp with simple voltmeter?

I know it won't be completely accurate but it might give you an idea. This is what I got when I measured mine at a given MV setting.

Hz Volts
60 4.7
50 6.6
40 5.7
30 14.3
20 27.6
10 35.7
5 20

I did think about this when we were trying to prove if an 18Hz filter is in place or not.

I asked Dayton again & they conformed an 18Hz filter is definitely in place but Sound Import are saying that is not the case & this is just where the amp "rolls off"

I guess this test with a multi meter would prove the filter is very much present if after 18Hz the voltage starts to fall off a cliff?
 
Last edited:
I didn't think many DMMs were accurate at such frequencies? I guess it depends on which device you have though. @Ringnut why does yours measure so much higher as frequency reduces? Is it a flat signal or with a shelf?
 
I didn't think many DMMs were accurate at such frequencies? I guess it depends on which device you have though. @Ringnut why does yours measure so much higher as frequency reduces? Is it a flat signal or with a shelf?

My current multimeter is a fluke 17B+

You are far my knowledgable about this them me Matt, to a noob like me it seems possible but I am just surmising really :laugh:
 
I didn't think many DMMs were accurate at such frequencies? I guess it depends on which device you have though. @Ringnut why does yours measure so much higher as frequency reduces? Is it a flat signal or with a shelf?

I was just trying to see roughly how safe I was at 'Ref' on the MV in normal use with my normal settings. I wasn't bothered about absolute accuracy, just a guide.

As previously posted I have filters in place in my 2X4HD that cut the output around the higher frequencies (40 & 60 in particular) in order to flatten the signal and with a slight boost towards 10Hz, hence the variation.

2X4HD filters.jpg


I was using one of these.

 
-- As an eBay Associate, AVForums earns from qualifying purchases --
Ok so that looks about right then, +8dB from 30 to 10Hz is about 2.5x and that lines up with your numbers
 
Worth a try though the dmm is only rated to 40Hz so might be some doubt about the measurements
 
So I removed a plate amp from one of the subs & just used a peice of scrap plywood roughly cut to cover the hole. I added some draught exclusion tape around the edges so hopefully it is pretty well sealed.

Installed the Speakon socket & wired up a fly lead to connect it to the NX3000.

IMG_3200.JPG


Place the sub back where it was when I took the other measurements & connected the sub to the NX3000. Ran it in bridged mode as I presume this gives the sub the most power the amp can deliver?

Here is the measured response at the same microphone position as before with the plate amp.
Behringer NX3000 Bridged Rear Right FIre Forward.jpg


Looks very similar so I presume a bigger amp is not going to fix my problem?

I got to thinking this a room issue so I moved the microphone to the front row just to see what sort of response I would get, bear in mind that the front row is further away from the sub.

Behringer NX3000 Bridged Rear Right FIre Forward Front Row MLP.jpg


The low end looks a little better?
 
Yes, that certainly looks a lot better. If you chop off that peak from 60Hz down to 20Hz that gives you a pretty flat response down to 12Hz. Can you try one of the other Hypex powered subs in that same position? Have you tried modelling your room with Room Sim?
 
So it's worth measuring the amp with a multi meter then?

It might be worth measuring both the Behringer and the Hypex and comparing them. Even if the DMM isn't totally accurate it will provide a consistent tool for comparison.
 
Yes, that certainly looks a lot better. If you chop off that peak from 60Hz down to 20Hz that gives you a pretty flat response down to 12Hz. Can you try one of the other Hypex powered subs in that same position? Have you tried modelling your room with Room Sim?

OK here is the response from a sub with the Datyon Plate amp in the same location & the microphone in the same place.

Dayton SPA1000 Rear Right Fire Forward Front Row MLP.jpg


Looks like the low end falls off much more to me. I guess this can only be down to the amplifers now then?
 
That is a high pass filter

Put both responses in rew, level match the peaks and then use A / B trace arithmetic. Post the resulting response and we can compare to an actual high pass filter. Or post the mdat with the two measurements.
 
That is a high pass filter

Put both responses in rew, level match the peaks and then use A / B trace arithmetic. Post the resulting response and we can compare to an actual high pass filter. Or post the mdat with the two measurements.

Will do Matt, for what these are worth I did the test with the multi meter and I have included the results below:

Dayton SPA-1000

50Hz – 1.80V

45Hz – 1.89V

40Hz – 1.80V

35Hz – 1.96V

30Hz – 2.27V

25Hz – 2.43V

20Hz – 2.24V

15Hz – 1.43V

10Hz – 1.08V

5Hz – 0.71V


Behringer NX3000

50Hz – 1.51V

45Hz – 1.57V

40Hz – 1.39V

35Hz – 1.50V

30Hz – 1.53V

25Hz – 1.44V

20Hz – 1.44V

15Hz – 1.28V

10Hz – 1.36V

5Hz – 1.21V​
 
I think I have done this correctly, both responses combined.

Responses of Both Amps Combined.jpg


Here is the mdat just in case I screwed it up.

Amp Comparison.zip

Looking at both responses together you can really see where that filter kicks in at 18Hz.
Dayton SPA1000 vs Behringer NX3000.jpg
 
Last edited:
Looking at both responses together you can really see where that filter kicks in at 18Hz.

Absolutely no doubt there and something you can use surely?
 
Absolutely no doubt there and something you can use surely?

I hope so mate as if not this is going to be very expensive :(

What do you guys think of the last reply I got from Sound Imports?

He is still adamant that there is no filter in place but when I ask Dayton they tell me without a doubt there is at 18Hz.

Is it just BS when he says the amp "naturally" rolls off & is not a filter? Sounds fishy to me, here is he last reply again.

Dear Adam,

I believe there is still some misunderstanding. The SPA1000 does not include a protection filter. The frequency response is 3 dB down at 18 Hz naturally. We call this a filter because it filters the response in some way. Another example (to understand the definition) is how an enclosure also acts as a high-pass filter. This whole roll-off has nothing to do with protection purposes, but is a natural response from the amplifier circuit.

I remember this whole conversation was started because you suspected a protection filter to be present that would affect your in room measurement. However you use an actively corrected (though DSP) response shared by an avforums user as target. If the forum user would share a response curve from the uncorrected UM18-22 it would look a lot more like the curve from your uncorrected setup. You should use thee miniDSP 2x4 HD to correct the curve to a flat one.

I hope this information is useful and clarifies the misunderstanding.

Obviously trying to use the 2x4 HD to correct the response just isn't going to happen.

I know when I contact him again he is going to say the same thing & I want to be sure I can call him out & tell him its BS.
 
You now have evidence from both Dayton and the sweep and I'm sure Matt could assist with some nice technical wording backing that up. :D

Edit: You would need to add a 10dB boost at around 12Hz just to get to the level of the Behringer which clearly is never going to happen so it is surely not fit for your purpose. This must act as a warning for anyone else intending to use these plate amps if they intend also to make use of BassEQ. :(
 
Last edited:
I don't think he is necessarily talking rubbish though. All amps roll off somewhere towards the lower end after all.

Personally I think your problem is that the amp has no published specs that mean anything, as with nearly all amps, so I am not sure on what basis a refund could be justified in law. I mean they don't even state the bandwidth for the power rating let alone the duration so the amp specs are essentially meaningless. Even if they went with FTC ratings then that is 20Hz-20kHz so wouldn't cover this sort of behaviour.

Obviously hope you can get it sorted though
 
This whole thing probably says more about Sound Imports than it does about the Dayton Hypex plate amp TBH. :(
 
Well after going back & fourth over the last week I am not getting anywhere, they wont accept the amps back due to what they call installation damage from where the screws have touched the plate.

They also say because I did not let them know I was building the subs with infrasonics in mind its not their fault.

They have offered a partial refund but it looks like I am just going to have to sell them second hand & take the hit.:(

I picked up some 18mm MDF yesterday to fill in the holes, just for fun they used 19mm thick MDF but in the UK the closest you can get is 18mm. :facepalm:

Anyway I have an idea how I am going to fill the holes but am interested in how you guys would approach it.

Going to try to fill & paint so you will never know there was a hole there, my main concern is making it structurally sound.
 

Attachments

  • image0.jpeg
    image0.jpeg
    264.8 KB · Views: 111
Valchromat comes in 19mm thickness

I would probably glue strips of wood under the cutout so they protrude into the gap then fasten the new piece onto that on top of it with some sort of sealant (those compressible strips used on doors or some sealant/adhesive)
 
Valchromat comes in 19mm thickness

I would probably glue strips of wood under the cutout so they protrude into the gap then fasten the new piece onto that on top of it with some sort of sealant (those compressible strips used on doors or some sealant/adhesive)

Never heard of Valchromat before, had a very quick look & its pretty expensive compare to MDF which soon adds up over four cabinets.

I got the pieces cut to fill the holes for all four cabinets today, ended up removing most of the horrible insulation.

Was a right pain trying to remove the contact adhesive I used to stick the insulation in but I got there in the end.

Managed to get the internal braces glued & clamped on one cabinet, I was just going to wood glue in the in fill piece on top of the bracing but you have got me thinking I should use some sort of sealer now.

I mean wood glue should make it air tight.
 

Attachments

  • image0.jpeg
    image0.jpeg
    521.1 KB · Views: 115
  • image1.jpeg
    image1.jpeg
    432.5 KB · Views: 100

The latest video from AVForums

TV Buying Guide - Which TV Is Best For You?
Subscribe to our YouTube channel
Back
Top Bottom