Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

I would build one myself, if I was you. Parts won't cost much on electronics stores and you can find circuit diagrams from internet.
Without lowpass filter it would be a speaker which might play lower sounds than other speakers, but it would be also playing the higher sounds, which would sound bad.

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

To run a subwoofer you need to tap into the sound signal - ie, through the headphone out port. But by doing this, it automatically turns off the internal speakers. So, without some sort of script to keep the speakers active, it's one or the other AFAIK.

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

Hi there.

I've been testing the subwoofer along with the n900.

For now i use an amp from other subwoofer to make the mini-sub to work and use this method to make it work along with the n900 speakers without having to open it up:

http://talk.maemo.org/showpost.php?p=722226&postcount=5

Must say that the result is awesome! Now i have to make the low-pass filter and receive the mini-amp.

Could someone say the exact components to make the low pass filter, so that i can go the electronic store and buy them? I went there today but they didn't know (neither did i :( ) what are the exact values to my project ( watts and that sort of things...). When i said i didn't know anything about electronics i wasn't joking :(

Thanks

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

hehe it works fine the fix with the alsamixer, thanks to qwazix

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

great stuff!!

didn't expect to find other diy audio guys on here. i'll have to post some details of my diy class D active speakers tomorrow.

They run from mains or self power via 60 Ni-MH cells - and have a smps / dc-dc in progress for car use.

Runs upto about 150 watt peaks before clipping with 55V rails. once i have the dc-dc going well should manage more.

the whole projects been on pause for months now - i generally get time to work on it around christmas, but i will post photos of its current state. the amps are entirely my own design built from op amps, logic ic, comparators, fet drivers and some tiny power fets all on diy pcb (double sided etched).

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

Nice, i didn't know about this "hack". Thanks for info. Anyway, as laasonen said, without lowpas filter, Your woo will try to play all spectrum. Once, I connected wrongly cables to 5.1 sound system - test voice was going through sub. VERY strange experience ;)

:eek:

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

Okay,

as promised .

First I should add that many of the parts used in these are what I happened to have around - I was trying to make these as cheaply as possible.

I built the cabinets years ago allowing space to later add amps in the back - which shortly after I did, some based on the design by Johan Sorensen (http://hem.passagen.se/johanps/).

No overly happy about these i set about designing my own inspired by his design.

Attachment 21254
From the front - Some fairly rough n ready looking DIY speakers.

Attachment 21255
From the rear - the one on the right houses the mains PSU ( A toiroid transformer (approx 350VA from memory - thogh not sure) for the 50V rail and a small 15V SMPS for the control voltage and battery charging).

The one on the left houses the batterys, amps and control circuit.

Battery bank

50 Cells (not 60 as earlier stated). They are configured as 5 banks of 12 Volt (2500mAh). 4 banks go in series to provide a nominal 48V (about 55 when fully charged) and the final bank provides the control voltage. When plugged in to charge the bank of relays configure each with a constant current regulator and each set of battery and regulator in parallel so will charge from around about 15 volts.

Control circuit

This has several functions - there is an MCU (atmega48p which controls the startup and shutdown procedure by switching transistors (which in turn switch relays) and monitoring supply and speaker rails for correct operation.
It also has a few LED's to show operating status and any fault conditions - including clipping - excessive clipping leads to automated shutdown in order to protect the connected speakers.
Clipping detection is currently crude - but is effective. It simply monitors each speaker rail (full bridge design so both for each speaker) if they get to close to 0V or the power rail a clip is assumed)

The amps

The amps are a full bridge design allowing for needing only one main power rail. A separate lower voltage (10v regulated) rail drives the logic, op amp, comparators and FET drivers/FET gates.
The power rail level has no effect on the gain of the amp - so is able to run from pretty much any voltage (between 10 and about 80) - this should with some extra effort make it possible to only run the large toroid when lots of power is required.
The design is a self oscillating type which oscillates at around 500kHz (with the help of a resistor/capacitor - it tries to run at about 1.6MHz left to its own devices which dissipates to much energy due to switching).
The power FETS are tiny!! 4mm by 4mm yet can deliver incredible power considering their dimensions. There is nothing more than a area of copper (reinforced by some thick copper conductors) on which they are mounted in way of a heatsink.

It was some time ago so i cant recall exact numbers but I think with a 1kHz sine wave dissipating 40Watts RMS into a test load resistor I measured approximately 95% efficiency.

I am using these for full range - not just to drive the bass units!

Speaker ocnnections
I have allowed for connecting the amps to other speakers. Whilst the speakers themselves are likely to be better than your average cheap home "HiFi" speakers - they are certainly no contender to Propper HiFi speakers.

These connection allow the amps to be connected to decent speaker so the amplifiers can be compared directly with others on a set of decent speakers.

Speakers
As you can see the cabinets are built from MDF. They have been designed according to the Thiele/Small parameters for the drivers - which are them selves some cheap Skytronnics things. Despite their costs (£15 for bass/mid driver - £8 for the tweaters) they are pretty good performers.

Attachment 21256

Attachment 21257
This is what i lashed up to make it easier to control - I initially had the pre-amps and volume knob on the rear of the speakers but this quickly proved inconvenient when used in the car. So this litte unit now contains the preamps, volume knob, and a USB DAC IC. There is a switch to select between analog/RCA in and the USB DAC.

Despite its appearance this setup sounds pretty incredible! I have had a number of audio buffs from various backgrounds (Some home HiFi enthusiasts (my dad included!) another electronics engineer who has worked with audio, and a guy who works with professional audio equipment for recording) listen to this and all have been amazed.

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

Is there any other "fix" with alsamixer that allows me to turn on the internal speakers + the headphone jack at the same time?

That fix that i mentioned earlier was the responsible for one of my internal speakers to blow up (or become silent) one year ago, on my first n900.

If you do that hack, the internal speakers gain much more bass and lose "surround power" ( it appeares to have less stereo widening).

You could try it but don't abuse on the hp dac value and then just unplug the jack and listen to the diference.

Is there any way to activate the speakers without those two "consequences" to happen?

Thanks

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

If i remember correctly, You mentioned that Your speaker blow up cause You "tweaked" some values to high, from "safe defaults" provided in hack thread. Maybe we just need to put values even lower? If not, I'm absolutely sure that stereo widening effect can be regained by just correctly mixing few different output gauges on alsamixer. Experiment, but don't put any higher than default value - it's better to gain little quieter effect, than blowing speaker ;)

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

That's what i'm doing now ;)
But is strange because it gains more bass with this hack, when it should provide the same sound . I've tweaked with all that parameters before without reaching the default sound :(

That is why i'm asking to someone that really knows what he is doing about this, before i do something stupid again :o

And i'm going to upload some videos, maybe tomorrow, with the n900 and the subwoofer to show you guys something, instead of just anoy you with this questions ;)

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

Just got a bunch of chips, 5x 2012 & 3x 2016

And can report that the 2016 is also very good, of course you need >10V to use it, but i have ordered some boost converters, and with the boost converter the amp for the N900 will be extern since it will take some space, but not more then a box of matches total, and thats pretty good for a 2x10W amp :)

here is the test model i just put together, battery powered from a 10000mAh 14.8V Transmetic RC battery.
Attachment 21313
Attachment 21314
Attachment 21315

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

I'm afraid that with boost converter, battery drain problem may become significant (ho ever, who knows - using 3000 mAh battery... ;) ).

BTW, using N900 with 2x3W amplifier inside cover, then connected to 2x10W amplifier outside, then to speakers - that would be "amusing", to say at least.

Now I'm waiting for someone to mod FM transmitter antenna in a way that we can connect it to pro ~10 meter antenna (or any steel mast with copper crocodile clips) and start pirate radio station ;)

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

When i get it i will measure power drain :)
But having 2x10W really rocks, there is a noticeable difference from the 2x3W, and even thinking about getting a pair of the 2x15W.

And i been thinking of the antenna thing to, also a gsm for when you are out and about where signal is scares, it happens....
One thing i have noticed tho is when having a USB cable in (not connected at other end) it acts like an antenna, it helps a little bit.

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

As i said yesterday here are a few clips recorded from my old n93 ( best stereo sound capture i have in the moment, but stupid focus).

"Normal" music (voice and instrumental):
http://www.youtube.com/watch?v=ovC7UH6fiXA

Instrumental music:

http://www.youtube.com/watch?v=C0ywByoib08

Trance music:

http://www.youtube.com/watch?v=oILJ68JxgRk

;)

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

Does help some, just need a lowpass filter to get the best out of it.

Maybe i should make a video with my dock, tho it is not the best sound, it is however more sound :)

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

As for better WIFI/GSM antenna, there is topic somewhere on this forum, where one guy posted picture of his N8xx device with modified stock case - he implemented micro connector for external Wifi antenna ;) I don't think that this could be much harder on N900... Haha, it seems that all modders think about similar modifications, @ some point.

Ps.

Using N900 with 2x15W amplifier is RIDICULOUS, lol. I see police report "Suspect was disturbing neighborhood in 2 miles diameter, using music from mobile phone..." ;)

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

For 9.8 minutes until suspect's battery ran out :D

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

No more time here with 3000mAh :D

and you have to take RMS instead, and then it is more like

then the party can go on for 44.4minuts - N900 power usage.
But hey a small 30min party. :D

Next mod for me is my BT speaker, it will get the 2x10W and Boost converter, it can play really loud on the 2x3W but before it was BT it was just the case and an external 12V 2x20W amp.

But if the 2x10W works fine im going to 2x15W :)

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

if i brought this 3W x 2 could i still connect it to the single n900 battery i have or would i have to order two of those scuds? and the big cover?

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

if you can fit a connector to your N900 then yes.
Another way is to fit a battery to the amp itself, but you have to figure out how to charge it then.

Don't need big cover or scud battery for this.

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

so i would need to get some solder and a short 3.5mm to 3.5mm the one i have is like 2 metres long

i only have like £13 atm lol so i need to make sure i can get everything in

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

yes get a short one :D

don't know if you can fit a plug in the N900 (stock cover).
or do you plan to have a battery on the amp, you can place it under the circuit board of the amp, im still asuming that you buy the board with the chip?

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

i was gonna try and just get wires coming out from the side of the back cover so its not fully on. and yeah im gonna get the board with the chip the one in the link i gave that you gave,lol. my parents dont give me alot of money so i need to save up to make it proper lol. im only 16. im gonna need like £30-£40 right if i wante the mugen cover+2scuds+amp

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

Yes thats about right, there is the cheaper dual 'christgift' option (2500mAh) but it's up to you.

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

if i buy the christgist can i use it with the original nokia i have?

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

Better not - if You connect batteries together, always use same chemistry (OK in this case), capacity, state of charge, and try to make batteries at least cycled equally, if not just new.

Of course mixing types will work, but Your capacity will be limited to 2x less effective battery capacity, and even batteries of exact same capacity, but from different manufacturers, may age differently. It's just a waste of better battery potential.

I understand Your limited budget, but better save for 2x christgift's + mugen cover, than mix one new battery with stock nokia one. More cost-efficient in long term :)

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

thanks for your help. i'll just save up and then order the three things when i get enough =D

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

got my boost converter today.

Input 4v - Idle current 144mA
Output 15.2v

so only 0.5W idle, thats not bad at all.
EDIT: and that connected to amp and speakers.

Next task now is to add it to the BT box, and this time maybe add it inside :D

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

Before anyone ask, for N900 that would be bad. 0.5W is 10% of normal battery, and about ~4% of dual-scud. For hour.

so, with N900 better stick to the 2x3W amp ;)

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

about the PMPO talk, i will just bring these up, i just found on EBAY.

NEW-EVO-LABS-PC-Laptop-computer-USB-Speakers-2-0-280W

The Specs
Magnetically shielded
Build in amplifier
Drive Unit: 3" Speaker
Controls: Volume, Power, LED
RMS Power: 2CH x 1.5W
PMPO: 280W
Voltage: USB powered
Frequence Response: 20Hz-20KHz
Separation: >= 40dB
Size: 78 x 85 x 185MM
S/N Ratio: >= 45dB
THD: =< 0.5%

Here we see 2x 1.5W RMS and 280W PMPO!!!!!!!!!!!!!
Also note that these extreme speakers are able to go down to 20Hz!
But goddamm S/N of over only 40dB?, if this is the case all you will hear is static, my home amp has an S/N beyond 105dB and crappy 80' amps had S/N over 80dB, so 40dB would not be a stat i would post, and i know that it has more....


Just found the same stupid speakers from another seller, but here they claim 600W PMPO!!!!

http://www.ebay.co.uk/itm/600W-USB-C...item4cf894046d

But at least the specs are more honest
Freq response 80Hz-20KHz

NOTE: When powered from USB like these are there is only 2.5W Power to use, this will change when someone makes a USB 3.0 version.... then 7.5W

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

Hi there.

I received the mini-amp-board yesterday and i've been testing it.
First thing i made was creating an external stereo system for my old n-gage. and it rocked! Tomorow i will post some photos.

My problem now is to create the lowpass filter. In the videos i posted before i was using the amp of a home-subwoofer, that includes a lowpass in it and the sound was what i wanted. But using this mini-amp the sound is like a normal speaker (as everybody guessed).

I created a lowpass of second order using this "tutorial" http://autosom.net/artigos/crossovers.htm but the resulting sound is the same.

Could someone say what are the best values for this setup (mini-amp, that mini-subwoofer) ?

Thanks in advance

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

Just reconfigured my original external amp to make it a bit smaller.
The output now goes in a 4 pin jack thats "mounted" on the amp, so now only one wire sticks out (power)

Attachment 22074
Attachment 22075
Attachment 22076


I think if i get around to it tonight i will make a youtube video showing the difference in loudness e.g. N900 playing normally on full, and with the amp and these sony speakers i just got (i get a lot of "junk" from everywhere, gets any worse i will probably be on hoarders :D)

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

Just shot a video, crappy video but you get the "picture", next one will be in a room/shed.....


N900 Micro AMP, powered from the N900 to small speakers

.

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

@dr_frost_dk;

http://talk.maemo.org/showpost.php?p...3&postcount=13

Can you just clarify what happened with the audio volume there? Because your system is very similar to what I built for my car (the one that has the slight crackle). I'm thinking of putting a VMA2016 10Wx2 in between the BT board and car head unit, to try to eliminate the crackle (and also increase the volume, as it's fairly quiet, despite the head unit having it's own amplifier).

Also, found this: http://www.ebay.com.au/itm/VMA2016-2...item4cfa16a086

Handy little mounted board. Any idea on the purpose of the capacitor?

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

Every audio amplifier needs power and the more current available the more output from the amp is achieved, think of it as a reservoir of energy which used to supply current to the amplifier as and when demands are made of it.

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

as abill_uk says.

But if you run these amps of good battery's in my experience you can omit the capacitor

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

Untill you start running kilowatts ;) then you need BIG caps or a wagon load of batteries ;).

When i lived in the Netherlands we had competitions on how quick your car would bounce a guilder off the roof with pure vibration from the speakers and massive output audio amps ALL homemade ;).

A nice little amp will always perform better with a "reserviour".

The post from 5spdvl's problem about "crackling" was most certainly down to insufficeant decoupling caps.

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

Well, naturally my system is running off a 12V DC car battery, as it's in my car. I'm going to buy a VMA2016, clean it all up a bit and see how that goes. :)

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

Make sure you you solder everything up well with no dry joints etc because that is a sure way to get rid of static, make use of decoupling caps where ever you can.

Re: DIY Audio thread, show you DIY audio 'equipment' (Amps, BT etc...)
 

Well the problem with car audio is the noise and interference from the generator, thats why a BIG cap helps when putting an power amp in your can, that and the power delivery.

If the noise you hear changes when the RPM changes then it is generator related.