Anyone ever use these Class D amps?

[aron]

I was thinking of making a small power amp with Shaka overdrive for the front end.
I guess the power supply would probably be heavier than the power amp.

http://www.parts-express.com/tda7492-digital-audio-amplifier-board-2x50w--320-606

[electrosonic]

No experience, but they can be had cheaper via ebay  (under $9 w/ free shipping)

http://www.ebay.com/itm/TDA7492-D-Class-High-Power-Digital-Amplifier-Board-2x50W-AMP-Board-with-Radiator-/141267388674?pt=US_Amplifier_Parts_Components&hash=item20e4314902

Andrew.

[petey twofinger]

i have seen those for that low price around ten but i am nervous  ... if i need another 50 x 2 board i was considering to give one of those a shot , for the price ... i am very curious , i would love to hear your findings if you make the purchase ...

the dimensions of that board are smaller than the sure electronics board with the same chip and rating . the heat sink is a different style and also the sure 7492 board , the 50 x 2 has a fan as well .

i believe i paid 22 dollars ( on sale ) shipped for my 50 x 2 , you can get those for 26 though . we blew one up , directly connecting a drum machine / zoom b2 to that board , but i was not there , cant vouch for what happened . now i run a mixer circuit before it . i do love the class d amps , the sure brand ones i am crazy about . we really used ours quite a bit , outdoors when its hot . we had that one issue , another time i plugged the wrong power supply into one , fried the chip , but i was able to install a new chip for three dollars , and it has run for an additional year plus .

right now for my rig , i run a 25 x 2 with a dual eq ( active bass pick up harness , 9 dollars ebay ) pushing it . i run two cheap PE horns , and four speakers 2x6 2x8 , which ohms out to maybe 6 or eight ... . a 12 v 7 mah lSLA asts 6 hours , at that point i swap out cause i have extras . i use lap top style power supply's i find used for inside use . they say you are not supposed to push these amps ( use a preamp ) most of our rigs use front ends with lower output ( my opinion , prolly wrong ) , since the ipod headphone lawsuits ( conjecture )  , a lot of headphone out gear is not as hot as it used to be , i think ... what i do know is i have pushed these with smalley npn  boosts and stuff like that , fairly hard and havent had an issue . but i should also mention the ones i pushed were NOT the 50 x 2 , they were 25 x 2 and especially the 15 x 2 , i slammed that and it runs very well .

combined with a "proper" front end ( shakka )  , any multi effect , especially a fancier unit with amp/cabsim , these amps are excellent IMO , i own a jc120 , several tube amps , a yamaha 120 x 2 combo , and a handful of smaller practice amps and many diy contraptions . my pandora is best used with a full range sound system , and thru custom patches i am thrilled with what i can get with minimal eq tweaks . my kids amp uses a microcube front end , and that amp is excellent as well . we have a 25 x 2 with a dual smally , 2 x 12's w/ horns for the keys / synth . ten a 50 x 2 that runs on 24 volts for the bass rig , which handles the drum machine  , on its own stereo eq , and then the bass signal , zoom b2 , with the mini mixer which is out of a super 8 to video converter box . i just finished a dual hotline 2 cabsim i am eager to try on my rig as well . but, a lot of this would be over kill  for normal folks . i over do things . the amp board not having the voicing a normal guitar amp has could effect things for some folks but ... nowadays , there are many ways around this , including turning the blind eye .

the only issue i have with the 50 x 2 , is when i crank the drums on some kits it will cut out , when its cranked . i slapped an eq together and that helped , but ... i am guessing if i figured out what impedance issue or something i could get a better  result but honestly , its way too loud as it is . sometimes , towards the end of the night i gt carried away and turn it up too loud ... a separate system for the drums would be ideal , but i am pushing it already , as we have been kicked out of one county so far .

there are videos on my channel but i am thinking all those are older , we didnt have the 50 x 2 yet , but you would get the basic idea ... it works very well , is what  i have found anyway  . i see a few other guys are doing this too . nux makes something called the amp force for 60 , i am prolly gonna get one at some point . i use my pandora at home as an interface so ... recently i have been running a pedal board and an effects loop . pedals into the pandora , out to the loop , then my stereo delay , then the eq's hit the amp . its more cables but hey ... doing it right , sometimes i guess that can be appealing to me when its a greater hassle . with modeling software being what it is , ipods and all , i could see slapping together some active speakers with internal laptop power supplys or even sla's being a viable option for almost any situation . but then one wouldnt be able to say things like "my stack" or " my tube amp" ....

sorry about the mega post , lemme know if you follow thru k ?

[aron]

How do you run these things in BTL mode?

[teemuk]

If you look at the internal block diagram, it reveals that each 50W channel of TDA7492 holds two class-D amps that are driven by opposite phase signals. So you just bridge the outputs of those two amps together: Load is connected in between the power amp outputs (OUTN & OUTP) instead of single output and common. In practice, each 50W channel is designed to operate in BTL as is.

[amptramp]

Class D is great because of the fact that you can get a lot of power in a small package.  I have an article in an old magazine entitled "40 Watts in 40 Ounces" indicating the other benefit - power to weight ratio.

What you have to understand about Class D is that it needs an output filter to get rid of the RF hash and the output impedance may not play nicely with that of the speaker.  Multi-section filters may interfere with the negative feedback, so usually, only single sections are used (or feedback is taken after the first section and may not represent the voltage at the speaker).  Make sure you understand what it can and cannot tolerate for an output load.

Also, make sure it has the FCC test sticker on it because it will have frequencies above 9 KHz which is where the FCC emission spectrum starts.  These are sold as modules, so if you incorporate them into a higher level assembly like a cabinet with a speaker, the FCC may see you as a manufacturer of an RF radiator and you may face the same punitive fines as Electro-Harmonix did.  If you build it for your own use, you may be exempt, but if you sell it, watch out.

[Gus]

Found this
http://www.st.com/web/en/resource/technical/document/datasheet/CD00205863.pdf

Looking at the distortion graphs I think some extra signal conditioning might be a good idea

I would think about a limiter and a lowpass filter and also a buffer to drive the input resistance of the two amps between the preamp(Shaka overdrive) and the amp(s)

[J0K3RX]

I found this by accident whilst surfing around looking for... ah...  I can't remember now    No matter.. this is probably cooler than whatever it was that I was looking for anyway! 

Complete with Eagle schematics and source code

I am not sure how it stacks up against other traditional designs as far as the sound quality is concerned but, it looks like a lot of fun and might give ya a chance to mess around with source code, microcontroller etc.. Take some time and look at the other stuff on his blog also, pretty interesting!

Microcontroller Class D Amplifier
http://rdimitrov.twistedsanity.net/blog/show.php?entry=Microcontroller%20Class%20D%20Amplifier

Microcontroller Class D Amplifier Rev2
http://rdimitrov.twistedsanity.net/blog/show.php?entry=Microcontroller%20Class%20D%20Amplifier,%20Rev2

[axemurderforhire]

I ordered a class d 2 x 50 yesterday and say this thread. Any thoughts on a preamp for the front end ? or should i just put some thing like a basic eq together.

[BubbaFet]

I don't know how I missed this thread before, but a cheap class d amp board, a cheap switch mode power supply,  a cabinet with a classic Celestion or Eminence speaker(s), and most important (!), some sort of DIY JFET front end preamp (effect),  makes an awesome rig that IMO beats tube amps any day of the week.

This has been my setup for a few years. now, probably around the same time as the OP.

I  built my own 'twin' amp with a Parts Express Sure class D board  https://www.parts-express.com/sure-electronics-aa-ab32165-2x25w-at-6-ohm-tda7492-class-d-audio-amplifier-board-only--320-332 $20, a Jameco.com SMPS http://www.jameco.com/z/LRS-50-15-Mean-Well-51W-15V-3-4A-Single-Output-Switchable-Power-Supply_2257555.html $12,  speakers $$, DIY JFET  preamp $10.

Put your money into your speakers, not your amp.  Oh, and good pickups are required too. They don't have to be expensive. Guitar Fetish pups are a steal. 

ARON! What did you end up using?