Hi,
This is my first post in this forum, i have been reading loads of threads over the last couple of weeks and i think im set on what i want to start my first dip in to diy audio with.
Ive got a need for an ipod docking set of speakers. My current plan is for a stereo gainclone amp, power supply and two full range drivers all put into an encloser that houses the lot. My plan is then to use an in cart ipod dock to connect the ipod and provide it with power so it can also be used to charge the ipod/not use the battery at the same time.
I have abit oif experience in electronics, done loads of soldering, point to point and on pcbs so im confident with any of that side of it. i have little experience with designing electronics, mainly only university stuff (mechanical engineering) simple circuits. i have no experience of designing or doing anything with audio though. Im happy using a kit but i want to do something a little different from just soldering a kit together and listening to the result, thats why i want to incorporate a speaker build and amp build into a neat ipod dock.
Im thinking of starting with the amp and im looking at the LM3886 chipamp but i dont really want to wait for 6weeks to get the kit sent from chipamp.com in USA. I thought i would buy the pcb's and then buy the components from farnell.com or equivalent.
im having problems finding the 0.1uF 63v -BC propylene capacitors (x6) without paying the £15 delivery from the US, does anyone know where i can pick these up in the UK?
I just wanted to setup this thread to start a bit of discussion about my proposed project and beginner projects in general.
This is my first post in this forum, i have been reading loads of threads over the last couple of weeks and i think im set on what i want to start my first dip in to diy audio with.
Ive got a need for an ipod docking set of speakers. My current plan is for a stereo gainclone amp, power supply and two full range drivers all put into an encloser that houses the lot. My plan is then to use an in cart ipod dock to connect the ipod and provide it with power so it can also be used to charge the ipod/not use the battery at the same time.
I have abit oif experience in electronics, done loads of soldering, point to point and on pcbs so im confident with any of that side of it. i have little experience with designing electronics, mainly only university stuff (mechanical engineering) simple circuits. i have no experience of designing or doing anything with audio though. Im happy using a kit but i want to do something a little different from just soldering a kit together and listening to the result, thats why i want to incorporate a speaker build and amp build into a neat ipod dock.
Im thinking of starting with the amp and im looking at the LM3886 chipamp but i dont really want to wait for 6weeks to get the kit sent from chipamp.com in USA. I thought i would buy the pcb's and then buy the components from farnell.com or equivalent.
im having problems finding the 0.1uF 63v -BC propylene capacitors (x6) without paying the £15 delivery from the US, does anyone know where i can pick these up in the UK?
I just wanted to setup this thread to start a bit of discussion about my proposed project and beginner projects in general.
it sounds like a good idea to me. I'm wanting to do something with my amplifier. I dont think i would
In my experience you will end up getting stuff from the states through farnel and cpc at some point
I've had a quick search but i can't find the pinouts for the ipod have you found them ?
to make things simple have you thought about the lm4780 in stereo?
In my experience you will end up getting stuff from the states through farnel and cpc at some point
I've had a quick search but i can't find the pinouts for the ipod have you found them ?
to make things simple have you thought about the lm4780 in stereo?
thanks for the reply, i no what you mean, there are a lot of components and i dont wanna get the worng ones. How critical is it that i get the same ones as the kit???!!
another question, this is probably a general question. How do you decide what transormer to connect to the amp?
Hi,
use the 3886.
For 4ohm speaker use a 18Vac transformer.
For 8ohm speaker use a 22Vac or 25Vac transformer.
Since you're in the UK I suggest you stick with 8ohm.
Do you want or need stereo or would mono do?
Look at the national datasheet. Study it from start to finish.
Take notes of any parts you don't understand and ask what they mean.
Look at fig 2 and note the presence of optional components. They are not optional. They are mandatory for every newbie and most experienced builders as well.
Build an AC coupled version. It must have DC blocking caps on both the input and on the Negative FeedBack (NFB) lower leg.
Will your docking station need very deep bass performance or is size/portability more important?
Then choose the input filters appropriately for your intended use.
use the 3886.
For 4ohm speaker use a 18Vac transformer.
For 8ohm speaker use a 22Vac or 25Vac transformer.
Since you're in the UK I suggest you stick with 8ohm.
Do you want or need stereo or would mono do?
Look at the national datasheet. Study it from start to finish.
Take notes of any parts you don't understand and ask what they mean.
Look at fig 2 and note the presence of optional components. They are not optional. They are mandatory for every newbie and most experienced builders as well.
Build an AC coupled version. It must have DC blocking caps on both the input and on the Negative FeedBack (NFB) lower leg.
Will your docking station need very deep bass performance or is size/portability more important?
Then choose the input filters appropriately for your intended use.
thanks AndrewT, i want pretty good bass response from the unit, but i know you need a lot of capacity in the speakers for a sub. Im going to check out that data sheet but i probabily will have more questions soon.
Cheers.
Ps, what are some good full range speakers for this application?
Cheers.
Ps, what are some good full range speakers for this application?
AndrewT,
I want a stereo amp, i have been looking at the stereo amp pcb's from chipamp.com but i dont really wanna wait the 6 weeks delivery.
If i go for the circuit on the national website taht you showed me, what would i have to do to get stereo, use 2 amplifier circuits and 2 power supplies? or would only 1 power supply be ok?
I think i would rather do it using the national circuit.
cheers mike
I want a stereo amp, i have been looking at the stereo amp pcb's from chipamp.com but i dont really wanna wait the 6 weeks delivery.
If i go for the circuit on the national website taht you showed me, what would i have to do to get stereo, use 2 amplifier circuits and 2 power supplies? or would only 1 power supply be ok?
I think i would rather do it using the national circuit.
cheers mike
I'm no expert, but I made a fairly good portable player using a Velleman P4003 kit (TDA1521)for an easy stereo amp, the MCM aluminum cove speakers slide up and off so they can be spread out. It's not audiophile, but it has a good balanced sound with MP3's. The amp actually is seperate and removable as I have a little Magnavox SE tube amp (6BQ5/6EU7) amp that can slide in it's place.
one more question i have (at the moment at least) on the national website, the circuit schematic it has Rm and Cs but it doesnt specify the resistance and capacitance we should use. Forstly, why is this? and secondly, what should i use?
cheers
mike
cheers
mike
Someone please correct me if I'm wrong here:
Rm sets the current on the mute pin, which is what determines if the chip is on or not. The necessary value is listed in the datasheet. The values of Cm and Rm form a time constant that determines how fast the cap with charge and how fast the chip will turn on. Essentially, you are supposed to calculate them based on your own needs. You could even omit Cm, if you don't want a start-up delay.
Cs are supply bypass capacitors, again the datasheet mentions what must be done to ensure stable operation. People tend to combine caps here, larger electrolytic with a small polyprop, or even up to a total of 3 different bypass caps. The chip has excellent PSRR, but still, follow the example of tested schematics and install something that's tried and tested.
Rm sets the current on the mute pin, which is what determines if the chip is on or not. The necessary value is listed in the datasheet. The values of Cm and Rm form a time constant that determines how fast the cap with charge and how fast the chip will turn on. Essentially, you are supposed to calculate them based on your own needs. You could even omit Cm, if you don't want a start-up delay.
Cs are supply bypass capacitors, again the datasheet mentions what must be done to ensure stable operation. People tend to combine caps here, larger electrolytic with a small polyprop, or even up to a total of 3 different bypass caps. The chip has excellent PSRR, but still, follow the example of tested schematics and install something that's tried and tested.
The LM3886 is a bit ambitious for a small full range speaker design. Why not a LM1875 or TDA2040?
To start out, I'd try something simple like a TDA1517. It is easy to build and you don't need a monster PSU or big heat sinks. 12volt 3 amp supply would be fine if you drive 4 Ohm loads.
To start out, I'd try something simple like a TDA1517. It is easy to build and you don't need a monster PSU or big heat sinks. 12volt 3 amp supply would be fine if you drive 4 Ohm loads.
hi, thaks for the replies guys. the lm1875 does look a lot simpler in the sample schematic in the datasheet oin nationals website. If i followed that to the T and used 2 amps for each channel is that right? would 2 amps need 2 supplies or can you run them off the same supply?
as far as the speakers im thinking of i just want something good quality and substantial without being over costly, i want bass response but i dont want a whopping car sub.
what would you reccommend?
as far as the speakers im thinking of i just want something good quality and substantial without being over costly, i want bass response but i dont want a whopping car sub.
what would you reccommend?
Unless you were planning on running bridged amps (paralleled), you only need one amp per channel, one power supply can run both amp/channels, if it is of sufficient size. However at your option you can run seperate PS to each amp.
baggies01 said:
Lower (and more) bass response usually means a bigger box. My 1st thot was mFonken is anout the size of LS3/5A, more efficient (and with fully modified driver, IMHO, better)
Mark Audio CHR70 would also be interesting -- 4-6 litre sealed (but need at least 4x the power for the same levels).
3" drivers will go into a smaller box, but are challenged to hit even 100 Hz.
dave
It is there to create a virtual ground. You only need it, if you use a single supply. With a split supply you don't need it.baggies01 said:
Except for the resistor and optional capacitor for the mute pin everything else is very much the same.baggies01 said:
Did you check this speaker?
http://www.diyaudio.com/forums/showthread.php?s=&threadid=47403
Oh, but you wanted pretty good bass response. So maybe this?
http://www.diyaudio.com/forums/showthread.php?s=&threadid=50153
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