How to build an active docking speaker

[Cypress]

Hi,

Been reading and reading about speakers and amps for the last 2 months and i only get more puzzled with all the possibilities. I don't have an electronics background but have been reading a lot on the subject. I would like to get hands on now and i have set myself this goal: build an active mono (for simplicity) speaker. In more detail i want to to the following:
build a speaker that consist of

• a woofer and tweater
• an amp of about 50 to 100W
• a passive crossover (if possible)
• a raspberry pi with a DAC as audio streamer (logitec media server & squeezelite)
• a power supply that is sufficient for the RPi and the amp

I have read about chipamps and gainclones and the different mythical creations (brianGT, ...), different chipsets, power supplies, but it is all so much to choose from.

I have not found an exact project like the one i would like to build so i don't know where to start.

is it safe to say that an active speaker is just a passive speaker but with the power supply and amp included in the box? Or is the wiring completely different?

Anybody attempted such a project?
Got some good tutorials or reading on this subject?


Thanx!

 

[TLS Guy]

Welcome to the forum.

I think this is about the third post we have had about this. However you seem to have done some research.

It is beyond the scope of this forum to do all the research and design for a project like this.

I would advise that you present what you have and plans, and we will be happy to critique and advise.

Not having a background in electronics is no barrier as long as you continue to do your homework.

Now your first critique.

A passive speaker has no amp and no source of power other than the speaker input.

A powered speaker has one amp and is either has one full range speaker or a passive dividing network to two or more speakers.

An active speaker has an electronic crossover before power amplification and each speaker driven requires its own amplifier. So if you do your two way active you will need two amplifiers.

Since you are new to this, it might be advisable to try and design to use wallwarts for the power supply, rather then build your own. This unfortunately is mainly for insurance reasons. However this is not an absolute, but you will need to be careful.

If you do build a power supply running run off 120 volt AC, you should have it checked by an experienced builder, or qualified tech. Otherwise if there is a fire you could be in a lot of difficulty.

Anyhow concerning the power supply, the output voltage will determine the power of the amp you can use. The power amp will need more voltage than the pi for instance. Voltage can be regulated down.

This is a good application for a chip amp. One of our members slipperybidness has a thread on a chip amp build.

You might want to send him a PM, after reviewing his posts.

You need a budget and need to make a reasonable choice of speakers, and how you want to load them, open back, sealed or ported for instance. Then I can certainly help you design the crossover.

It would be helpful if you could indicate what level of fidelity you require from this unit.

For this first build, I would recommend a powered build and not an active one, to cut the design and build work required.

So research it more and present your plans and selections and then we can comment.

 

[slipperybidness]

Like TLS said.....for the chipamps/gainclones, check out my thread on just that topic. It is kind of out of place on this forum, it would be better suited for DIYAudio or PETT forums.

I can't remember....is BrianGT the owner of ChipAmp or AudioSector?

I can tell you that I personally steered clear of AdioSector. His philosophy on PCBs and amps seemed to lean a little bit into audiophile voodoo instead of hard-core measurements and specs. But, the main reason that I didn't choose his PCBs was because those would take more mods than the ones that I did buy to get to the end-result circuit that I wanted.

As far as ChipAmp, I bought a bunch of components, chips, etc from him. And, at least at one time AudioSector and ChipAmp were working together.

As far as amps go, just a couple other items to consider. If you have questions on Chipamps, then I'm probably here to answer or point you to someone that can. If you are considering purchasing an amp:

1) A consumer amp like this: http://www.parts-express.com/lepai-lp-2020a-tripath-class-t-hi-fi-audio-mini-amplifier-with-power-supply--310-300

2) Or perhaps an amp module like this:
http://www.parts-express.com/yuan-jing-l12-tta1943-ttc5200-mono-power-amplifier-module-120-watts--320-6522

http://www.classicaudioparts.com/index.php/featured/icepower-170w-amplifier-module-complete-with-power-supply.html

 

[Cypress]

Thanx for the info guys. I've done some more research on the powered and active concepts. It seems to me that i'd better start of with an active speaker. I've read some good things about DSP. These days it should be as good as an active XO. Correct?
Since i will need a DSP module and 2 amps i had my eye on the Hypex AS2.100 230Vac. Do you have any experience with that. Its much more expensive but it has power supply, amps and dsp in one device.
I was also thinking about maybe a miniDSP 2x4. Its way cheaper but i need to take care of power and amps.

Next is the box. i will go for a sealed one. this is the area that i haven't done a lot of research on. I have bought 'the reference' in speaker building books (so they say ) 'designing, building and testing your own speaker system'. So i guess i will start reading that.

Best regards,

Cypress