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DIY desktop speakers
(9 posts, started )
#1 - Joris
DIY desktop speakers
I want to build my own desktop speakers. I have a T-class amp as on the picture below. It can drive about any 4 to 8 ohm speaker. This amp is fed by a good USB-DAC.



I do not need a lot of bass or vollume, just decent sounding speakers for music which do not have too much of a footprint on my desk.

I am thinking about closed MDF enclosures with 10 cm car speakers.

Does anyone have experience with such a project (or just some good suggestions)?
I'm getting many different hits for that amp name, but all the specs seem similar. You'll probably need to go down the car speaker route, as your amp won't deliver enough power for conventional 8 ohm bookshelf speakers, most have a minimum higher than your amps output. Car speakers (I think) are 2 or 4 ohm, so you'd should have enough for those.

I don't know much about building speakers, but the majority of the cost of hife speakers is the cabinet. A good, strong, sturdy design is best, with plenty of acoustic foam inside to absorb resonances.
Well, it depends on wich compliant the ratings are done. If it is on the same compliant as my current 20 year old amp (2x15w) then it should be more than enough. My 2x15w are powering 2x90w (max) speakers wich are also rated at this same compliant. But my 90w max speakers outperform Logitech Z5500 systems with ease, in matter of power and quality. So basically, find out what compliant ratings this amp has. Im trying to say that in reality, a 1000w amp can be 100w on the right complaint and some 50w and be 100w on another one. Rockford fosgate uses CEA-2006 compliant for they amp ratings for example.

About the ohm law, check wich one is the minimum on this amp. It cant just "drive one and another with ease" - if u put 4ohm speaker on it while minimum is 6ohm then u will fry ur amp. At some points u can put lower ohm speakers on amps but mostly u can just put volume as high as u can just hear something playing, going higher will cause more voltage and then it shorts out. Ofcourse, u can always use resistors to make the ohm bigger. See the ohm law here.

About the 10cm car speakers, i wouldnt recommend these. Get something more "meant to play in home". Its a long known fact that car speakers are meant to be played in cars, home speakers meant to be played in homes and PA speakers on big stages and outside. Once i had PA setup with massive 4x15" woofers and such, it just couldnt play in my home. But still got the SPL, so it made me wanna go poopoo.

For the enclosure, MDF should do for this size speakers.

I hope this helps, inform us with ur own toughts tho.

Edit: U can also calculate the real power out of checking the power consumption. 200w + 2 channels should pretty much give u the answer: 200/2 = 100w. Works nicely for regular amps wich dont have much more features on it like radio and such, so the power goes to the amp > speakers. On recievers and such its a bit more complicated.
Quote from hazaky :Edit: U can also calculate the real power out of checking the power consumption. 200w + 2 channels should pretty much give u the answer: 200/2 = 100w.

That won't tell you the %THD at that output level.
#5 - Joris
Thanks for the input so far guys.

Quote from Bob Smith :I'm getting many different hits for that amp name, but all the specs seem similar.

T-amp is a familly of amps which are built around a Tripath-IC. It's implemented by many small-scale ampbuilders which are active on ebay. As far as I know all of them are good apart from the ones with tone control.

I am favouring car speakers for the following reasons:

They are intended for use in a closed cabinet (no bass reflex) this makes it a lot easier to implement. No wave length calculations necessary, just make sure the cabinet volume is sufficient. (correct me if I am wrong).

Coaxial two way car speakers save me from to fiddling around with cross-over filters. I can just wire straight from the amp to the speaker terminals.

Car speakers are allways 4 ohm (at which the amp works best).

Because of the generic sizing it's very easy to upgrade later on.
Quote from wheel4hummer :That won't tell you the %THD at that output level.

Well, true. Was just throwing out some basic knowledge for him.
#7 - Joris
There is no way of deriving the output power from input when the efficiency is unknown. T-amps are kind of D-class amp, these are very efficient compared to class A and class A/B amps. I have a class A tube/mosfet headphone amp which is more hungry than the T-amp even though it can only power headphones.

However, the specs of this amp are no mystery. These are the specs:

I'm using that amp with a pair of Alesis Monitor one MKII speakers. Goes loud enough for my taste and it sounds quite good. It does need a good power supply though, some power supplies will cause a humming noise.
#9 - Joris
I purchased a 5A power supply with it from the same supplier. No noticable noise what so ever.

DIY desktop speakers
(9 posts, started )
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