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nilsonsound - an ongoing story

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Category: General
Forum Name: 12v Powered Systems
Forum Description: From Mini-rigs to ICE, all your low voltage audio needs here...
URL: https://forum.speakerplans.com/forum_posts.asp?TID=106491
Printed Date: 18 January 2022 at 7:28pm
Software Version: Web Wiz Forums 12.03 - http://www.webwizforums.com


Topic: nilsonsound - an ongoing story
Posted By: nilspixel
Subject: nilsonsound - an ongoing story
Date Posted: 23 August 2021 at 5:03pm

Some time has passed since i started my 12v project. Afterall it's an ongoing constant learning process :)

What i came up with so far:

2x THAM15 with PD 15.50

8Ω 600W RMS

2x Self-designed 12" Cabinets with Emince Delta Pro 12A
8Ω 300W RMS

2x Fairly Cheap Sica z009442 +Q07032B in self built cabinets
AES Power     16 W above 3 kHz
Program Power     32 W above 3 kHz
Sensitivity     105.5 dB (Q07020A)
Frequency Range     1000 Hz ÷ 19 kHz (Q07020A)
Recomm. Xover Frequency     above 2500 Hz

1x GreenCeel 12V 90AH AGM Battery

1x Pioneer GMD 8740
4x100W Rms 4Ω
2x300W RMS 4Ω

1x 4x4 DSP t.rack
The setup looks something like that. every speaker is wired in parallel so they are 4Ω.
Watts:
Thams get 150W each
Mids get 50W each
Highs also 50W each
https://ibb.co/ysQMWTf" rel="nofollow">

Pro:
  • It actually works!
  • It looks nice (hehe :D)
  • My calculations for the mids kind of work out pretty good.
  • I can get around town with my bicycle!
  • Medium volume is nice.
Con:
  • More Bass! Reggae music always asks for more bass! So this is a point where i'd like to make changes. Give my thams more output power.
  • Better highs. The cheap things on top are on the one side fairly cheap and small. On the other side all high tones sound kind of cheap which sometimes is a pain in the ears...
  • More voulme would be nice!
Changes:
  • I thought about a new high-speaker. Instead of two small shitty ones i'd go for a http://https://www.thomann.de/de/bms_4554_8_ohm.htm" rel="nofollow - BSM 4554 i n combination with a http://www.thomann.de/de/bc_me90_alu_cd_horn.htm" rel="nofollow - B&C ME90 Horn.
  • More power means another amp. Here i'm not sure wheter its best to get a mono amp or a 2channel amp bridged to one channel.  For example i found this http://www.eton-gmbh.com/en/products/car-hifi/amplifiers/product/power-4502/" rel="nofollow - Eton 450.2 Amp which gives me bridged 908W RMS on 4Ω. So i could get around 450W for each of my thams out of it. Moneywise it's more power for less money in comparison with other monoblocks. Whats the point?
  • More Amps means different battery. I thought about getting a LiFePo4 100AH. Is there a need to get powercaps when using LiFePo4?



Replies:
Posted By: Jack1991
Date Posted: 25 August 2021 at 10:59am
Looking good mate! How do you find towing it by bicycle is it hard work?


Posted By: nilspixel
Date Posted: 25 August 2021 at 4:21pm
thanks mate!
Its fine on flat streets. When it comes to hills its quit hard without ebike power. Fortunately i have a motor on my cycle ;)


Posted By: infrasound
Date Posted: 25 August 2021 at 6:13pm
Given you achieve 150W out of your current amplifier then the increase to 450W is a decent 5dB more. You'll be much closer to justifying such a chonky driver at that point.

There's another 4dB available if you had a horn extension, equivalent to a 1100W amplifier at that point, without the extra power consumption. Could fold it up and 'deploy' when wanted.

Also, I'm sure you've checked - but given the overlap currently between your mids and the Thams, the phase is well worth getting dialled in.

Given the SPL you'll be at, the 4554 is likely overkill - but it sounds great!


Posted By: nilspixel
Date Posted: 26 August 2021 at 3:50pm
Originally posted by infrasound infrasound wrote:

Given you achieve 150W out of your current amplifier then the increase to 450W is a decent 5dB more. You'll be much closer to justifying such a chonky driver at that point.

Yes, i think i go for this Eton Amp. Does someone has experience on running two amps from one battery?

Originally posted by infrasound infrasound wrote:

There's another 4dB available if you had a horn extension, equivalent to a 1100W amplifier at that point, without the extra power consumption. Could fold it up and 'deploy' when wanted.
Horn extension sounds good, is there any information to be found?


Originally posted by infrasound infrasound wrote:

Also, I'm sure you've checked - but given the overlap currently between your mids and the Thams, the phase is well worth getting dialled in.

yeah, thats back from when i was doing some weird experiences... :D

Originally posted by infrasound infrasound wrote:

Given the SPL you'll be at, the 4554 is likely overkill - but it sounds great!
You mean smaller ones fit better?





Posted By: toastyghost
Date Posted: 26 August 2021 at 3:52pm
Originally posted by infrasound infrasound wrote:


There's another 4dB available if you had a horn extension, equivalent to a 1100W amplifier at that point, without the extra power consumption. Could fold it up and 'deploy' when wanted.



Tapped horns (and other horns) need some consideration for a horn extension to ensure the internal flare rate is maintained, and the driver offset created isn’t going to cause a horrible notch in the response by pushing it out of 1/4 lambda.

You can however get a fairly good ~3 dB broadband increase with any stack of subwoofers by making a portable baffle extension that increases the cabinets’ combined frontal area to 3 times the original value. Some flat pieces of 18 mm or greater thickness wood with fold-out outriggers do the job just fine, especially if they’re braced at the back to reduce resonance.

https://www.diyaudio.com/forums/subwoofers/184986-horn-extender-wave-guide-th.html" rel="nofollow - https://www.diyaudio.com/forums/subwoofers/184986-horn-extender-wave-guide-th.html

This is, of course, at the expense of omnidirectional bass coverage - may or may not be a good thing for a portable battery system.

You can even put a logo or some art on them.


Posted By: Phil B
Date Posted: 27 August 2021 at 1:38am
Horn extensions on TH.... yep...

%20" rel="nofollow - https://forum.speakerplans.com/th-unity-horn-24v-solar-sound-system_topic63191.html

.p.

-------------
Mostly harmless.... except if catering is shut.

Solar Sound System Shennanigans.. http://diyhifi.biz/" rel="nofollow - http://diyhifi.biz/


Posted By: infrasound
Date Posted: 27 August 2021 at 1:57pm
I tried tempting Jack quite a bit in this thread!  http://https://forum.speakerplans.com/lockdown-audio-a-12v-3way-small-rig-build_topic105202_page1.html" rel="nofollow - http://https://forum.speakerplans.com/lockdown-audio-a-12v-3way-small-rig-build_topic105202_page1.html

I would be happy to strap together a basic sim to show the size with an extension, but I am far from an acoustic engineer. I'd be more than happy to help with the mechanical design though.


Re. 4554 - it's a 1.4" designed to do 1kHz+ at high SPL (which you will never reach, being heavily limited by the THAMs)

Better IMO to go with a 1" driver such as BMS 5530ND mated to a PH-3220. Cheaper drivers are available such as B&Cs 1"ers.

That combo is both cheaper, sweeter in the HF, better horizontal dispersion and over 2Kg lighter Star


Posted By: nilspixel
Date Posted: 27 August 2021 at 2:51pm
thanks for your explanation ;) i will consider it for my future plans!

can someone say something about Stetsom preamps? they seem to be fairly cheap for a lot of power.. i don't trust them for now..

https://www.stetsom.com.br/en/produto/hl-1000-2-2-ohms/" rel="nofollow - https://www.stetsom.com.br/en/produto/hl-1000-2-2-ohms/
what they state:
Power @ 12.6V Bridge 4 Ohms1 x 1000W RMS
Harmonic Distortion 0,4%... quit high isn't it?

another one, perfectly matches my 600W RMS
https://www.stetsom.com.br/en/produto/hl-1200-4-2-ohms/" rel="nofollow - https://www.stetsom.com.br/en/produto/hl-1200-4-2-ohms/
Power @ 12.6V Bridge 4 Ohms2 x 600W RMS
Harmonic Distortion 0,9%.....(???)




Posted By: infrasound
Date Posted: 27 August 2021 at 3:57pm
Thumbs Up

I only know a little of car amplifiers, but those small Brazilian amps (don't know why specifically Brazil) have a particular reputation (I hear) for over-inflating their specifications. 

If you can find someone who's actually benched some, might be your best bet. Perhaps trawling some car audio forums / YT.

Although, arguably efficiency is just as important - but that data is far harder to come by. Maybe the only thorough approach here could be to buy a few, run 1/6 pink noise through them to match SPL and measure their power consumption. Not a quick answer though.


Posted By: nilspixel
Date Posted: 28 August 2021 at 11:48am
yesterday evening i realized that at a higher volume you hardly feel bass anymore. do the thams get outplayed? is it a power problem?

i forgot to mention that for now i only have one 15" installed because of delivery delays...

---------------------------------------------------------------------

Found some nice informative videos for calculating all that power needs within a system... its really basic but i needed someone to explain it to me :P
https://www.youtube.com/watch?v=zh0x8CiW4f0" rel="nofollow - https://www.youtube.com/watch?v=zh0x8CiW4f0

So idealy lets say i run on 14,4 Volts (maybe with some power adapter in the future).

Lets say i use a Rage 1200.2 and my Pioneer 8704:

Single
1200W/14,4V = 83,34A/0,8 =104,2A
600W/14,4V = 41,7A/0,8 = 52,1A

Both
1200Watts RMS + 600Watts Rms at 14,4V = 1800W
1800W/14,4V = 125 A
125A/0,8 = 156,26 A

So my powersurce should be able to do that..



Posted By: bob4
Date Posted: 28 August 2021 at 6:57pm
Originally posted by nilspixel nilspixel wrote:

yesterday evening i realized that at a higher volume you hardly feel bass anymore. do the thams get outplayed? is it a power problem?

i forgot to mention that for now i only have one 15" installed because of delivery delays...

--

The empty cab might eat some of your output......


Posted By: nilspixel
Date Posted: 29 August 2021 at 1:43pm
sure it does ;) just for a completion of this diary here...


Posted By: infrasound
Date Posted: 31 August 2021 at 5:42pm
One cabinet with a 150W input is going to run out of steam before your mids and tweeters, especially outdoors. Looks up ISO 226 to get an idea of relative SPLs.

And as bob mentioned, the empty cabinet next to it may absorb some of the energy radiated.


Don't worry about the THD, anything below 1% at amplifier is decent enough.


You won't be playing sine waves for long durations, so your cables will be quite overspecced'. You could potentially reduce their size if they're unmanageable (bend radii / mass). Shorter is always better of course.


Posted By: nilspixel
Date Posted: 03 September 2021 at 10:26am
What i ordered today:

...LiFePo4 100AH 200A (400A max.) + Shunt
...Rage 1200.2


Posted By: nilspixel
Date Posted: 28 September 2021 at 4:51pm
Update:

I installed the rage 1200.2 today. agm is replaced by lifepo4.

problem:
after ~1 min after I powered up the rage Amp the Pioneer starts to make a high frequency sound.. when I turn off the rage this tone disappeares instantly..

what's going on here?... any ideas?


Posted By: infrasound
Date Posted: 28 September 2021 at 6:34pm
Feedback on the ground line / power heading down the signal ground is my guess.

Does it go away if you disconnect the signal connections? Try buying a ground loop isolator and adding it on the inputs to the rage amplifier.


Posted By: nilspixel
Date Posted: 28 September 2021 at 8:33pm
I was wrong! But thanks for your reply!

The probelm was the new rage itself. I opened up the whole thing to check if parts are loose. i tightened some screws, noise is gone.

But one problem remained:
As soon as i use the second amp (rage) my high speakes start to make weird noises even though there is no signal coming from the dsp. i wired both power cables directly to the battery +. When i disconnect the rage from the battery, noise is gone. My assumption is that both amps interfer with each other somehow... may a powercap solve the problem?

Any ideas on that?


Posted By: infrasound
Date Posted: 28 September 2021 at 9:48pm
Powercap, no. They are of questionable effectiveness to stop voltage drops - and you aren't pulling anywhere near enough to be in that realm anyway.

My answer to your last point is more or less the same, so not wasted. Because the power GND and signal wiring in 12v systems are often shared (or too closely related), it can be needed to isolate them to prevent interference. 

My suggestion is to try the isolator in various spots until the problem disappears.

Or, it may work to use a separate isolated DCDC power supply for the DSP




Posted By: nilspixel
Date Posted: 29 September 2021 at 7:48am
thanks a lot infra! I'm going to try your suggestions today to see if it affects anything ;)


Posted By: studio45
Date Posted: 29 September 2021 at 1:59pm
I'd guess that a high pitched whistle is gonna be due to the two Class D amp's oscillator frequencies interfering with each other and producing an audio-frequency tone. Most amps use a free-running oscillator whose frequency isn't particularly stable or locked to any reference clock, so if you've got two amps on the same battery bus, and one is running at 400kHz and the other one 405kHz, you're going to get signals of 5 and 805kHz appearing on the system ground. 
I've also experienced noise emanating from cheap Bluetooth reciever boards - this is due to the chip involved pulling very short, sharp pulses of current from the supply at a rate with at least some audio-frequency components. No amount of passive filtering (extra caps near the BT board) makes it go away. The only way is to use little 5v-5v isolated converter bricks to power the BT board. However of course you need to connect signal ground "around" the isolator somehow otherwise there's no circuit for the audio signal to flow. Using a 1000uF cap across the rail after the isolator and a 100r resistor to link BT ground to audio ground seems to work well for me - the 100r is enough to make most of the interference flow thru the 1000uF cap to the isolated ground rather than out onto your audio ground. Small transformers would also work but more expensive.


-------------
Studio45 - Box Builder Commotion Soundsystem -Mobile PA


Posted By: samsk
Date Posted: 22 October 2021 at 11:30am
Hey, been really interesting to read this and really great system! I've built a similar 12v system this year (I've done a post here which can be found under 'compakt sound system'). I'm struggling to get my mini dsp to sound good, lots of unpleasent crackling noises, it sounds great when I take the dsp out or power it from my 240v amp rack, I was wondering if you'd be up for sharing some more screen shots of your setup? The crossover screenshot was really useful but I'm not sure about the other settings. If you'd be up for it maybe you could send me your settings as a preset file? Big thanks, Sam


Posted By: nilspixel
Date Posted: 25 October 2021 at 1:27pm
Does anyone know if its a bad idea to get a different speaker unit for the secons still empty tham? the PD1550 is not available at this moment.... i was looking at Eighteensound 15LW1401 instead..

Eighteensound 15LW1401

 

PD1550




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