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Topic with many replies

Create your own festival stereo


Author Message
Written on: 11.06.2012 16:30
Ruslabox
Posts: 168
Per Andersen wrote:

Do anybody know if you kan get some sort of amp, that can amplifi the sound from you Mp3 player, before the sound enters you main amplifier, for a resonable price, or if is not for sale on the poblic market, kan you make something yourself?

hope to get my question answered. icon_confused.gif


Unless you have a REALLY big stereo one amplifier should be more than enough. Given its not a crappy cheap one, a 20W amp should be able to get you to 90-94 dB, which is about the legal limit at Roskilde during daytime, twice the legal limit at night (not that anybody actually cares or can do anything about you playing loud music).

...my point being that you won't ever need two amps unless the one you already have is just crap, in which place you should replace it.
Written on: 12.06.2012 14:22
Kasper Lund
Posts: 9
Ruslabox wrote:

Per Andersen wrote:

Do anybody know if you kan get some sort of amp, that can amplifi the sound from you Mp3 player, before the sound enters you main amplifier, for a resonable price, or if is not for sale on the poblic market, kan you make something yourself?

hope to get my question answered. icon_confused.gif


Unless you have a REALLY big stereo one amplifier should be more than enough. Given its not a crappy cheap one, a 20W amp should be able to get you to 90-94 dB, which is about the legal limit at Roskilde during daytime, twice the legal limit at night (not that anybody actually cares or can do anything about you playing loud music).

...my point being that you won't ever need two amps unless the one you already have is just crap, in which place you should replace it.


I am guessing that Per Andersen is refering to a preamplifier which is not that uncommon! - If your main amp has a inproper set input sensitivy, compared to the signal you are feeding it, it may be nessecary to amplify the voltage level of your signal to utilize the full range of your "main" amplifier. A preamplifier is just a voltage amplifier and can be found many places (on ebay for instance)
Written on: 12.06.2012 16:01
Per Andersen
Posts: 15
Kasper Lund wrote:

Ruslabox wrote:

Per Andersen wrote:

Do anybody know if you kan get some sort of amp, that can amplifi the sound from you Mp3 player, before the sound enters you main amplifier, for a resonable price, or if is not for sale on the poblic market, kan you make something yourself?

hope to get my question answered. icon_confused.gif


Unless you have a REALLY big stereo one amplifier should be more than enough. Given its not a crappy cheap one, a 20W amp should be able to get you to 90-94 dB, which is about the legal limit at Roskilde during daytime, twice the legal limit at night (not that anybody actually cares or can do anything about you playing loud music).

...my point being that you won't ever need two amps unless the one you already have is just crap, in which place you should replace it.


I am guessing that Per Andersen is refering to a preamplifier which is not that uncommon! - If your main amp has a inproper set input sensitivy, compared to the signal you are feeding it, it may be nessecary to amplify the voltage level of your signal to utilize the full range of your "main" amplifier. A preamplifier is just a voltage amplifier and can be found many places (on ebay for instance)


No my problem is not my main amp, as it is a 4x100W tripath, it plays loud enough with a laptop conected, but if i connect my mp3 player (its kinda oldscool with a AAA batteri) you can clearly hear the difference, and it cant feed my amp with enough sound to play it to the max, and ofcause i would like to do so. so do you got any suggestions? icon_smile.gif

[This article was edited 1 times, at last 12.06.2012 at 16:02.]
Written on: 13.06.2012 00:18
Kasper Lund
Posts: 9
my point excactly. You can do 2 things to sort this matter. you can either change the input gain settings of your amplifier or you can buy a preamplifier.. There are tons of them out there.. here is just an example i found by writing preamp on e-bay

http://www.ebay.co.uk/itm/MP3-Player-Audiophile-Quality-Impedance-Matching-Preamplifier-MADE-USA-/330741706790?pt=Other_MP3_Player_Accessories&hash=item4d01bdf026#ht_500wt_1413

i have not tried the above so i don't know if it is any good.. Option one is still prefered if you ask me!
Written on: 14.06.2012 05:14
Macy Gray
Posts: 4
I am coming from overseas to Roskilde this year and need advice on the best place either in Copenhagen or Roskilde town to buy a speaker for camping. As we arrive the day before, we do not have the time or resources to build a large speaker setup, however we would still like to listen to our music through set of speakers that are stronger than the typical ipod-dock speakers, like this

http://store.apple.com/au/browse/home/shop_ipod/ipod_accessories/speakers

All we are after is large speakers and an auxiliary input, to play our mp3 players through..

Any suggestions?
Written on: 17.06.2012 01:43
Mikkel Hintz
Posts: 1
Hej folks!

Vi er nogle gutter godt igang med at bygge vores Roskilde-musik vogn. Vi er dog stødt på et rimelig træls problem, vores forstærker gider af mystiske grunde ikke at starte? Vi har så fundet ud af at anlægget skal have en stel-forbindelse, men vores vogn understøtter af mystiske årsager ikke denne forbindelse ordenligt. Er der nogen der har en god idé til hvordan vi kan få forstærkeren til at fungere? Vi bruger en almindelig Harald-Nyborg trækvogn til brug af transporten af musik-anlægget.

Håber vi kan få vores forstærker til at starte!

Forstærker: http://carsound.dk/produkt.asp?id=8833&pk=13&produkt=Renegade_AMP1100S_-_Forst%E6rker

Vogn: http://www.harald-nyborg.dk/p9977/traekvogn-m-luftgummihjul-en71

Hilsen en frustreret gruppe af musik-elskere!
Written on: 18.06.2012 23:21
Anders
Posts: 4
I have a few questions on building a half boominator

First of all:
http://a2.sphotos.ak.fbcdn.net/hphotos-ak-snc6/c48.0.403.403/p403x403/181444_3906912506653_1263067527_n.jpg

I made this amazing piece of are in paint. Is this the right way to do it? And i would also like to know how strong the resistors have to be?

Second of all:

I have read something about, that you need to use some kind of cooling on the AMP6. Is this true? and if it is, that is the easiest and cheapest way to do it?


Last of all:

the AMP6 has a jack stick input right? can i just use a converter from jack to mine-jack, and the use my phone directly on it?
Written on: 24.06.2012 22:22
Kasper Lund
Posts: 9
@Anders: there are many drawings of what you are trying to do at the boominator thread on diyaudio. But just to answer some of the questions. yes you can use a converter... on the amp 6 you have a right channel and a left channel.. You gotta use both of them.. so on your drawing you should have a l+,l- and a r+,r- going to your output

@Mikkel: din vogn har ikke noget at gøre med din forstærker icon_biggrin.gif stel er bare en reference. PÅ et 12volts batteri er der så at sige 12 volts spændingsforskel mellem + og - (eller stel hvis du vil) på batteriet.. Så hvis din forstærker ikke vil starte skal i kigge på hvordan i har forbundet jeres forsyning til den og ikke på hvordan vognen ser ud icon_biggrin.gif
Written on: 28.06.2012 09:57
SuperRajar
Posts: 1
This years festival stereo is finally done!

http://desmond.imageshack.us/Himg11/scaled.php?server=11&filename=dsc0036tc.jpg&res=landing

http://imageshack.us/g/11/dsc0036tc.jpg/

[This article was edited 1 times, at last 28.06.2012 at 09:58.]
Written on: 11.07.2012 20:32
Folmer Brem
Posts: 1
Hi everyone!

I have returned from Roskilde with some dissatpointment over my festival stereo. I build it from a lot of hi-fi guides on horn-speakers on the internet, so to everyone:
DON'T build a hi-fi blaster! It doesn't work outside.

Thats why I've desided to make something more like a boominator.
I found 4 tweeters - all non-piezo - two with a 8Ω rating and two with 4Ω rating. I understand that it is best to make filters for thoose guys, so in order to save components I would think that a simple capacitor could do the job for each tweeter.
My question is:

Do I need a real RC-filter og does the tweeter do the 'R'-job as 8Ω or 4Ω, even though it isn't quite so 'R' in the real world.

I used this calculator and aimed for a 1kHz cutoff
http://sim.okawa-denshi.jp/en/CRhikeisan.htm

[This article was edited 1 times, at last 11.07.2012 at 20:33.]
Written on: 11.07.2012 21:16
Saturnus
Posts: 3047
I'm willing to bet that your tweeters will not handle 1khz especially with a 1st order x-o. Depending on the tweeters minimum should probably be between 3 and 5khz. But it's hard to say without knowing the tweeters in question and the woofers you plan to cross over to.

Anyways, it's easier for you to just use a standard passive x-o calculator like http://www.ajdesigner.com/crossover/crossoverfirst.php
Written on: 22.03.2013 15:01
Mere Vand i Dejen
Posts: 6
Hi all

Having had the pleasure to read this amazing thread, I’ve decided to build a festival stereo with the famous AMP6-Basic.
Our camp is not planning to have big parties for the entire festival – this is just for the 10 of us, when we are not at concerts.

Never the less, we still want it to play loud enough to be hearable for ourselves, in case that we will be living next to a big party camp.

So far I’ve come to decide that I will,
- order the AMP6-Basic preassemled
- use two Dali II speakers
- be using a 12v SLA. Not sure how many Ah yet

Speaker specifications:
Impedance: 8 ohm
Sensitivity: 89dB/1w/1m

I have some questions regarding how I should connect the Dali speakers to AMP6:
1. Should I connect one to each channel on the amp, so that the effect would be 50% due the 8 ohm impedance? (Isn’t that right?)

2. Or should I connect the two speakers in parallel to make them 4 ohm? (Are there any disadvantages to this?)

3. As I want to connect an iPod to the stereo, will I have to do any soldering to make the low-signal-output from the iPod amplified?

Thanks in advance!
Emil


[This article was edited 3 times, at last 22.03.2013 at 15:03.]
Written on: 22.03.2013 16:32
Saturnus
Posts: 3047
1. Yes
2. It would be mono (the topic here is festival stereo icon_razz.gif)
3. No. Just specify in your order that it's for ultra-low output source.
Written on: 22.03.2013 17:24
Mere Vand i Dejen
Posts: 6
Saturnus wrote:

2. It would be mono (the topic here is festival stereo icon_razz.gif)


That's what I thought icon_razz.gif

Thanks for the super fast and accurate reply.

Can you tell me if ~98 dB is a realistic goal with this setup? (Which is fine for me)

I'm not super good at these loudness 'calculations', but I have tried anyway:
89 dB = 1w
92 dB = 2w
95 dB = 4w
98 dB = 8w

Is there anything I forget to take into account?


[This article was edited 2 times, at last 22.03.2013 at 17:32.]
Written on: 22.03.2013 17:39
Saturnus
Posts: 3047
Mere Vand i Dejen wrote:
Can you tell me if ~98 dB is a realistic goal with this setup? (Which is fine for me)

I'm not super good at these loudness 'calculations', but I have tried anyway:
89 dB = 1w
92 dB = 2w
95 dB = 4w
98 dB = 8w

Is there anything I forget to take into account?



Above is correct for one speaker and sustained levels. MaxSPL is 107dB though as you get +6dB from there being 2 speakers each with it's own amp channel so you also have double the power. And you +3dB from maxSPL being measured at peak and not RMS.

The maximum average level is between 95-97dB since music signals average 12dB below peak level (if it follows the RIAA mastering guideline). 10dB below peak was common for a brief period during the "loudness war" though.

[This article was edited 2 times, at last 22.03.2013 at 18:09.]
Written on: 22.03.2013 17:53
Mere Vand i Dejen
Posts: 6
Saturnus wrote:

Mere Vand i Dejen wrote:
Can you tell me if ~98 dB is a realistic goal with this setup? (Which is fine for me)

I'm not super good at these loudness 'calculations', but I have tried anyway:
89 dB = 1w
92 dB = 2w
95 dB = 4w
98 dB = 8w

Is there anything I forget to take into account?



Above is correct for one speaker and sustained levels. MaxSPL is 107dB though as you get +6dB from there being 2 speakers each with it's own amp channel so you also have double the power. And you +3dB from maxSPL being measured at peak and not RMS.

The maximum average level is between 95-97dB since music signals average 12dB below peak level (if it follows the RIAA mastering guideline). 10dB below average was common for a brief period during the "loudness war" though.


Thanks! Makes perfect sense now.

Had never heard of "the loudness war" until now. Then I see that it even has its own Wikipedia page. Such a stupid phenomenon!
Written on: 22.03.2013 19:46
Mere Vand i Dejen
Posts: 6
How would I calculate battery time at full volume?

I have tried doing this:
Let's say the battery is 60Ah.

P = Voltage squared, divided by Ohm doubled = W

Battery time = 12V * Ah, divided by W * 2 (as I have 2 channels) = Hours I can play

Example:

P = 12^2 / 2*8 Ohm = 9W

9W * 2 channels = 18W

Battery time = 12V * 60Ah / 18 W = 40 hours
(Multiplying 60Ah with 12V to get Wh)

Will this work?



[This article was edited 1 times, at last 22.03.2013 at 19:53.]
Written on: 22.03.2013 20:05
Saturnus
Posts: 3047
Mere Vand i Dejen wrote:

How would I calculate battery time at full volume?

I have tried doing this:
Let's say the battery is 60Ah.

P = Voltage squared, divided by Ohm doubled = W

Battery time = 12V * Ah, divided by W * 2 (as I have 2 channels) = Hours I can play

Example:

P = 12^2 / 2*8 Ohm = 9W

9W * 2 channels = 18W

Battery time = 12V * 60Ah / 18 W = 40 hours
(Multiplying 60Ah with 12V to get Wh)

Will this work?




Yes. Except you forgot that the average in music signals is 8 times lower (-9dB) than the RMS value. And you forgot the efficiency of the amplifier. A class D amplifier typically uses 4-5 times less power with the same output power as a class AB amplifier.

Since you have the amp6b we know exactly how much power it uses. This is at maximum unclipped volume.

Amp6b @12V @8ohm = 210mA
Amp6b @12V @4ohm = 360mA

You don't mention the type of battery but since you say 60Ah which is typical for a car battery, and car batteries have only about 60% of their nominal capacity available for continuous loads. So if we say you have 36Ah of usable capacity that (36Ah / 210mA = ) 171.4 hours at maximum volume.

Typical average usage is only about 1-1.2W though, so expect to it to last at least the whole 10 days of the festival.

[This article was edited 1 times, at last 22.03.2013 at 20:07.]
Written on: 22.03.2013 21:19
Mere Vand i Dejen
Posts: 6
Saturnus wrote:

Mere Vand i Dejen wrote:

How would I calculate battery time at full volume?

I have tried doing this:
Let's say the battery is 60Ah.

P = Voltage squared, divided by Ohm doubled = W

Battery time = 12V * Ah, divided by W * 2 (as I have 2 channels) = Hours I can play

Example:

P = 12^2 / 2*8 Ohm = 9W

9W * 2 channels = 18W

Battery time = 12V * 60Ah / 18 W = 40 hours
(Multiplying 60Ah with 12V to get Wh)

Will this work?




Yes. Except you forgot that the average in music signals is 8 times lower (-9dB) than the RMS value. And you forgot the efficiency of the amplifier. A class D amplifier typically uses 4-5 times less power with the same output power as a class AB amplifier.

Since you have the amp6b we know exactly how much power it uses. This is at maximum unclipped volume.

Amp6b @12V @8ohm = 210mA
Amp6b @12V @4ohm = 360mA

You don't mention the type of battery but since you say 60Ah which is typical for a car battery, and car batteries have only about 60% of their nominal capacity available for continuous loads. So if we say you have 36Ah of usable capacity that (36Ah / 210mA = ) 171.4 hours at maximum volume.

Typical average usage is only about 1-1.2W though, so expect to it to last at least the whole 10 days of the festival.


Sounds like plenty of battery time. Awesome.
I'm a bit curious about how you did the calculations on the 210 mA.

I saw in an old forum post that you used this formula: (0.92 * 12^2) / (2 * 8 Ohm) = Power (W)
How did you get mA? Should I bother, or is it too complicated?
Written on: 22.03.2013 21:47
Saturnus
Posts: 3047
Both the 210mA and 360mA figures are not calculated. They are measured in use. They're actually lower than the calculated figures which are:

12V into 8 ohm stereo : 12^2/8 (leave out the 2 as it's stereo) = 18W * 80% (as we want the figure before clipping) = 14.4W / 88% (efficiency in 8 ohm) = 16.4W / 8 (for average music signals) = 2.05W / 12 (voltage) = 0.17A + 0.06A (quiescent current) = 230.5mA

12V into 4 ohm stereo : 12^2/4 (leave out the 2 as it's stereo) = 36W * 80% (as we want the figure before clipping) = 28.8W / 84% (efficiency in 4 ohm) = 34.3W / 8 (for average music signals) = 4.3W / 12 (voltage) = 0.36A + 0.06A (quiescent current) = 417.1mA

As noted. Use the actual measured figures instead of the calculated figures.



[This article was edited 1 times, at last 22.03.2013 at 21:49.]
Written on: 02.04.2013 18:01
Mere Vand i Dejen
Posts: 6
I have recently started thinking about using solar power and a 7 Ah SLA for my stereo.

Saturnus, how do you connect the solar panel to the batteries?

- Do you use a charging regulator or do you just plug the solar power directly into the batteries?
- Can you charge and play music simultaneously?
Written on: 03.04.2013 02:07
Classic rock dude!
Posts: 2492
Saturnus:

Are you able to tell whether this one is worth the money?

http://www.thehut.com/electronics/audio/the-house-of-marley-bag-of-rhythm-portable-audio-system/10647770.html
Written on: 16.04.2013 20:10
Lapiki
Posts: 22
Over a year and a lot of experience later:

I have finally begun ordering the part for my wagon, but i have a few final questions:

Would the schematic work:
http://postimg.org/image/dg1g0hpsz/
(sorry could not get the picture to work)

I am going to use the USB for charging mobile devices(i read that USB uses 5v and 500mA). Would the simple 10 ohm resistor work, or do i need something the keep it from destroying my battery?

I am going to use the ciggarettænder to run an electrical pump(it runs on 12v)... again, will this be enough or do i need something fancy?

Are the resistors between the piezo and HP-10W the right size and are they placed right(i saw this build on this forum, just want to make sure)?

How many A would this system use(without having something plugged into the USB or ciggarrettænder)?
Written on: 18.04.2013 16:20
Lapiki
Posts: 22
I solved the problem with the resistors on the piezo... i thought those where placed wierdly. I found this solution reading on another forum. As you might guess i am making half a boominator, but i saw saturnus mention that he uses some sort of coil, to take the peaks from the hp-10W(if i understood right). I also saw mentioned that you should maybe use a diode the prevent the power the the battery, running into the solar panels. Will i need this?

But i still need help with the previous questions.

Here is an updated version of my schematic:

http://postimg.org/image/hswq3rqwz/

[This article was edited 3 times, at last 18.04.2013 at 16:42.]
Written on: 18.04.2013 16:53
Saturnus
Posts: 3047
You're going to have a 10 ohm resistor to make the voltage drop on the USB? Good luck with that, hope you don't value whatever you connect to it. Also I hope it's big as there's going to be 15W dissipated on it. Thankfully the battery will die after 3-4 hours so it won't be a hazard for long.

I have no idea why you don't just buy a USB charge output for the cigarette lighter adapter. They're usually less than a dollar on ebay.

[This article was edited 1 times, at last 18.04.2013 at 16:57.]


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