2 x Ultimax 18's Unrealistic expectations or something wrong?

[Pete Basel]

Re: 2 x Ultimax 18's Unrealistic expectations or something wrong?

Pete,
Physically, the O-Audio amps were identical in many respects to the PE BASH 500, but with different features like PEQ that set O-Audio apart. Screws are in the same places, power boards look the same... control boards differ, as expected.

They measured one back in 2007... BASH architecture prevented the amp from reaching full power in steady-state use, but it sure has the extension! ([email protected], with the 12Hz setting I suspect.)

Have fun,
Frank

Thanks Frank, I wanted to buy a pair sometime back but they were on back order for a long time,
finally just went with the PE 500W unit. I'm interested in the schematic just to see how they
went about getting the features. I did also like it very much, seemed to be just the right set of
features.
They measured one? Is the report online somewhere?
Right you want the filter real low with an 18" so many of the amps with fixed filters have limited
applications or else need mods.

[Jeff B.]

Re: 2 x Ultimax 18's Unrealistic expectations or something wrong?

Thanks Frank, I wanted to buy a pair sometime back but they were on back order for a long time,
finally just went with the PE 500W unit. I'm interested in the schematic just to see how they
went about getting the features. I did also like it very much, seemed to be just the right set of
features.
They measured one? Is the report online somewhere?
Right you want the filter real low with an 18" so many of the amps with fixed filters have limited
applications or else need mods.

Click on the number 2007 in Frank's post. It's a hyperlink to the test.

[Pete Basel]

Re: 2 x Ultimax 18's Unrealistic expectations or something wrong?

Thanks, didn't notice that on my laptop display.

The limiter is probably good for saving the speaker.

Nice that you can tune the HP so low, but can you disable the boost? It is perfect for a
6th order vented design, or a sealed design with lots of volume displacement where you
want a bit more extension but an option for less boost or none would be nice, even if it
was jumpers or dip switches on the board. I'll have to check the spec about disabling the
boost, don't remember, but my design needed it anyway.

Sorry to take this off topic, better to split this off and I think that the discussion is good so
that a good set of requirements might result in some better plate amps.

[joshp214]

Re: 2 x Ultimax 18's Unrealistic expectations or something wrong?

Sorry I haven't updated, but here is what I did, and it sounds much better, but there is still a long way to go, as you can see I still have a few just completely empty holes in the sound, and some strong rolloffs. First, I turned the volume of the AVR to the volume I listen to movies at. I started from scratch on my eq, and started tweaking. I named my target frequencies in the PEQ on the Inuke 20hz,25,30,35,40 etc. I boosted the low end pretty strong, and it worked well, but it wound up overdriving the subs. I added in a limiter at 117v, and that problem was resolved. To further dial in the SPL, I turned on the SPL meter, and the tone generator on REW and then went back in the DSP and further tweaked each PEQ fq. I have also now eliminated the 60hz buzz, but have also effectively killed all other sound right there as well.

I have not moved the subwoofers yet, but I want to try that soon because I believe one of the subs is not being effective in its current location. I also want to add in some acoustic panels to try and kill some of the echo in the room (not that I believe it will help the subs much).

Anyway, here is my new graph. Red is the new, Purple is the old.

[Adam_G]

Re: 2 x Ultimax 18's Unrealistic expectations or something wrong?

You need to invest in a Minidsp, in my opinion. I would bring down those peaks at ~37 and 27hz, cut off the mountain tops and make it one long plateau from 19hz to 60hz. Your 60hz buzz is a grounding issue most likely somewhere in your amps, and should not have to be dealt with in your signal controls, there's an underlying issue there.

[Jeff B.]

Re: 2 x Ultimax 18's Unrealistic expectations or something wrong?

Sorry I haven't updated, but here is what I did, and it sounds much better, but there is still a long way to go, as you can see I still have a few just completely empty holes in the sound, and some strong rolloffs. First, I turned the volume of the AVR to the volume I listen to movies at. I started from scratch on my eq, and started tweaking. I named my target frequencies in the PEQ on the Inuke 20hz,25,30,35,40 etc. I boosted the low end pretty strong, and it worked well, but it wound up overdriving the subs. I added in a limiter at 117v, and that problem was resolved. To further dial in the SPL, I turned on the SPL meter, and the tone generator on REW and then went back in the DSP and further tweaked each PEQ fq. I have also now eliminated the 60hz buzz, but have also effectively killed all other sound right there as well.

I have not moved the subwoofers yet, but I want to try that soon because I believe one of the subs is not being effective in its current location. I also want to add in some acoustic panels to try and kill some of the echo in the room (not that I believe it will help the subs much).

Anyway, here is my new graph. Red is the new, Purple is the old.

Well personally, I like the purple line better. It's flatter and will subjectively sound more extended rather than just having a lot of output in one region, which can really be annoying in a subwoofer. I would have just added a bit of boost in the 20 Hz range and gone with a steeper low pass crossover. All in all, this appears to be what should be expected from UM18's in a sealed box, and it really pretty good performance too.

[jeff_free69]

Re: 2 x Ultimax 18's Unrealistic expectations or something wrong?

You need to invest in a Minidsp, in my opinion. I would bring down those peaks at ~37 and 27hz, cut off the mountain tops and make it one long plateau from 19hz to 60hz. Your 60hz buzz is a grounding issue most likely somewhere in your amps, and should not have to be dealt with in your signal controls, there's an underlying issue there.

Does miniDSP cause any significant delay ? Assuming we're doing an additional A-D/D-A trip on the sub there must be some latency in that , no?
OR, since the sub its already physically removed by a few feet, it doesn't matter.

(I have one but never tried mixing it with straight analog)

[Adam_G]

Re: 2 x Ultimax 18's Unrealistic expectations or something wrong?

Does miniDSP cause any significant delay ? Assuming we're doing an additional A-D/D-A trip on the sub there must be some latency in that , no?
OR, since the sub its already physically removed by a few feet, it doesn't matter.

(I have one but never tried mixing it with straight analog)

If you're using a room-correction in your surround sound receiver, it will take care of this delay (if it's great enough to require any difference) by treating the sub as if it were further away, therefore sending its signal sightly before that of the other speakers.

[jeff_free69]

Re: 2 x Ultimax 18's Unrealistic expectations or something wrong?

If you're using a room-correction in your surround sound receiver, it will take care of this delay (if it's great enough to require any difference) by treating the sub as if it were further away, therefore sending its signal sightly before that of the other speakers.

thanks - good point , but I wasn't clear about my application ...
- I was thinking of my 2ch setup which is all analog has and dual powered subs under the 2-way mains.
Before I got the dual sub amps I thought about using the mini-dsp there....

[Face]

Re: 2 x Ultimax 18's Unrealistic expectations or something wrong?

thanks - good point , but I wasn't clear about my application ...
- I was thinking of my 2ch setup which is all analog has and dual powered subs under the 2-way mains.
Before I got the dual sub amps I thought about using the mini-dsp there....

Running the subs and speakers through the MiniDSP would resolve any delay issues. As far as the additional conversion steps, I've read mix results. What you may experience is a higher noise floor, and since you are using multiple ribbons for HF, it may be an issue.

[jeff_free69]

Re: 2 x Ultimax 18's Unrealistic expectations or something wrong?

Running the subs and speakers through the MiniDSP would resolve any delay issues. As far as the additional conversion steps, I've read mix results. What you may experience is a higher noise floor, and since you are using multiple ribbons for HF, it may be an issue.

I've seen it used to good effect in some budget driver designs and its a great design tool. But when I tried a simple A/D - D/A passthrough (stereo in/out, no XO no EQ etc ), in direct comparison to pure analog, the soundstage flattened for me ( but what can you expect for ~$100).

Now if you can keep everything in digital domain and then use a couple of really nice D/A converters, that's the cat's pajama's. But that's getting really OT.

I was asking about mixing analog stereo main + minidsp Subs and possible latencies.
I'm thinking any sonic limitations when used on sub would not be noticeable. But every msec of latency is like moving the sub another ~foot away. Just wondering if anyone's tried this.

Sorry if this still getting OT for OP's issue - I should just dig up my mini and try it myself! Looks like a rainy weekend so who knows

[corradizo]

Re: 2 x Ultimax 18's Unrealistic expectations or something wrong?

It looks like you are making progress. I don't know if you've seen this guide, but it's been enormously helpful for me in learning how to get my subs tuned. Below I've posted a link to post #275 which is where the guide is kept updated.

http://www.avsforum.com/forum/91-audio-theory-setup-chat/1449924-simplified-rew-setup-use-usb-mic-hdmi-connection-including-measurement-techniques-how-interpret-graphs-3.html#post22823228

I've also found another guide that is also very helpful when you have more than one sub that may not be co-located. See link below.

http://www.avsforum.com/forum/155-diy-speakers-subs/1713458-mtg90a-s-multiple-subwoofers-mains-integration-how-thread.html

My experience based on having two subs co-located at 6' apart, one below each main on my front wall, taking all measurements from main listening position with REW and UMM-6 and a combination of analog and HDMI measurements:

Once you've poured over these guides I would recommend that you first connect directly to your sub amp from your laptop using the analog headphone jack rather than going to your AVR via HDMI. Doing so bypasses any filter your AVR has in place for the LFE. The sub amp should be completely reset with no filters in place, no crossover set, Deq off, etc. In order to EQ your subs you want to capture the entire range they are capable of reproducing and then make that ruler flat - this will also help you decide where you should cross them over to your mains. What is not in the guides above is what I've discovered reading around the forums. What i learned is that if you choose to cross your subs at 80hz, they should be able to be smooth an octave above that for proper blending with your mains. Yes they will start to roll off at 80hz but if you've eq'ed them flat, they will roll off smoothly. Similarly your mains should be able to play an octave below 80hz as well, for the same reason. My mains are in-wall and can't get to an octave below 80hz so i cross them at 120hz since they can cleanly play down to 60hz. Audyssey set them to 50hz, which they can reproduce but not so cleanly. So i don't use audyssey anymore (although in all fairness my Onkyo NR609 only has Audyssey 2eq a basic version). Once you have your subs flat and picked your crossover based on your sub/mains/center's capabilities as outlined above, you can level match everything using the tones in your avr and start to measure your subs and mains as a system where the mains (L and R - some prefer to do this with just the Center) and subs play at the same time. Now you can set your delay in the avr for the subs as the physical distance isn't always correct. This is where i found the second link I posted most helpful. I measured at 1 foot increments (limitation of my AVR) and then compared all the graphs which allowed me to select the distance setting where the mains and the subs were most constructive at the crossover point. If i've got any of this wrong I hope the guys on this thread will set me straight.

FUN STUFF!!!

Pete

[joshp214]

Re: 2 x Ultimax 18's Unrealistic expectations or something wrong?

Thanks for the advice! I think experimenting with locations, and then time alignment are my next obvious steps, along with fixing my ground loop issue. Thanks again for the help.

[---k---]

Re: 2 x Ultimax 18's Unrealistic expectations or something wrong?

I have not moved the subwoofers yet, but I want to try that soon because I believe one of the subs is not being effective in its current location.

You're going about this the wrong way. EQ should be last resort after room position options have been exhausted.
If you can move the subs, you should do this first. The hope is that you can find a location that you don't need eq or minimal eq.