heres my amp:
I built it so I'd have something portable, that I could take with me somewhere and plug into some floor speakers ( or small more portable bookshelf speakers)
Its based on the TDA7264 chip by ST. I adapted it for single supply operation and am useing 32 volts to run it ( regulated printer power supply) I've noticed that without a lot of bass boost ( I have to use my computer's EQ and boost the bass in volume controll ) the chip says its power bandwidth is from 20hz-20 khz. How come my lack of bass? I notice that on some really low notes you will see the woofers moving, but no gutteral sound will be made. I'm running it through my marantz sp1200's, when I use my fisher amp and its doing only 5 watts you can feel that bass. ( the amp has a power meter on it so I can see where it peaks and rms's out) Would an op-amp fix my bass problem on this amp, or does the chip really stink that bad? Also, since my power supply is only 940 ma, could it be a lack of amperage thats causeing the bass rolloff? what about my input caps? their the reccomended 1uf 50 volt caps ( I found very small ones ) ? could it be my output dc decoupling caps? their 470 uf 25 volt, should they be bigger? can the pot affect frequency responce at all? any help would be greatly appreciated! 😀 thanks!
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
I built it so I'd have something portable, that I could take with me somewhere and plug into some floor speakers ( or small more portable bookshelf speakers)
Its based on the TDA7264 chip by ST. I adapted it for single supply operation and am useing 32 volts to run it ( regulated printer power supply) I've noticed that without a lot of bass boost ( I have to use my computer's EQ and boost the bass in volume controll ) the chip says its power bandwidth is from 20hz-20 khz. How come my lack of bass? I notice that on some really low notes you will see the woofers moving, but no gutteral sound will be made. I'm running it through my marantz sp1200's, when I use my fisher amp and its doing only 5 watts you can feel that bass. ( the amp has a power meter on it so I can see where it peaks and rms's out) Would an op-amp fix my bass problem on this amp, or does the chip really stink that bad? Also, since my power supply is only 940 ma, could it be a lack of amperage thats causeing the bass rolloff? what about my input caps? their the reccomended 1uf 50 volt caps ( I found very small ones ) ? could it be my output dc decoupling caps? their 470 uf 25 volt, should they be bigger? can the pot affect frequency responce at all? any help would be greatly appreciated! 😀 thanks!
... would help to drop the schematics... 😉
Yes, could be that your dc-coupling cap is too small or lower quality...
mic
Yes, could be that your dc-coupling cap is too small or lower quality...
mic
http://www.st.com/stonline/books/pdf/docs/4541.pdf
I also ordered this chip, Its basicly the same accept the gain is adjusted externally. See page 2 of 9, it shows the schematic for single supply operation, thats how I adapted this one. ( obviously minus the gain resistors, and I didnt include the mute circuit on my amp, their the same though.)
http://www.futurlec.com/Philips/TDA7264.shtml
heres my chip. Retards, they list it as a philips...its made by ST, haha.
so what do you mean by dropping the schematic..listing the links here for you to see or just going at it without one 😕
Hmm.. Ill try the output caps, what value would you reccomend I replace them with?
I also ordered this chip, Its basicly the same accept the gain is adjusted externally. See page 2 of 9, it shows the schematic for single supply operation, thats how I adapted this one. ( obviously minus the gain resistors, and I didnt include the mute circuit on my amp, their the same though.)
http://www.futurlec.com/Philips/TDA7264.shtml
heres my chip. Retards, they list it as a philips...its made by ST, haha.
so what do you mean by dropping the schematic..listing the links here for you to see or just going at it without one 😕
Hmm.. Ill try the output caps, what value would you reccomend I replace them with?
An externally hosted image should be here but it was not working when we last tested it.
heres the circuit board, the output caps are right behind the connector on the board, the yellow wire is right and white is left ( denoting which cap is left/right) their 470 uf 25 volt. Should I use larger caps? because these are substituted from the other schematic.. maybe 1000 uf? what voltage would they have to be for 25 watts ?
I read a few application notes. It looks like c9 and c10 are 10x small than they should be or usually are.
Play it safe go with 50volts
Play it safe go with 50volts
ok. Yeah, my filter cap is 1000 uf 35 volt, I have a 50 volt one I'm gonna use instead. wow.. so do you think 22 uf would suffice for output caps?
ThSpeakerDude88 said:
The 1000uf 35volt cap should be OK. You need to change c9 and c10 to around 4700uf.
ThSpeakerDude88 said:
By output caps do you mean c9 and c10 on the application notes. If you do 22uf is much to small. Incease from 470uf to 4700uf
oh ok! Well, I have to replace the filter cap too, I plan on running my amp at over 35 volts ( up to 40 with a saftey tolerance) and right now I'm running it at 32 volts, so I dont have much of a headroom. Ill try the 4700 uf. Hey by the way, I have 2 caps in my capacitors box ( I desolder tons of componenets and use them again) Their 4700uf 25 volt, short and big modules that came off of a JBL pro amp. The thing is I dented the cans while getting them off ( I pried against each other with a screw driver...yes this was before I knew as much about electronics, the only reason I took apart that amp was because I learned a harsh lesson on proper bridging of an amp...) anyways, the caps seem to be fine otherwise. Think they'll do for now?
I wouldnt use anything less than supply voltage. You can test one channel with the 4700uf caps. You have by running them in series,that will gave you 2350uf 50volts. If you get more bass in one channel,it the output caps.
hahaha woot.. I just found out my caps are 16 volt! No wonder, they probably can't take that surge very well can they?
haha, the output caps. I tried the 4700 uf caps temporaily, much better bass, although not as much bass as my fisher has, but then again it has a 62 hz - 16 khz 5 band EQ on it, So I think my amp is flat now. I'm gonna wire these caps up , I think I'll be fine for now with 25 volt,at least untill I upgrade the power supply, don't you think?
You won't get close to 25volt on the output. It should be ok in the short term but I would change the out caps asp. Incease the supply cap to over 2000uf.
ok.. what will that do besides filter noise and have a lower pop on startup? the amp is dead silent btw, i mean dead silent, with or without signal. And the power on pop is a silent click barely heard over the sound of the click of the switch on the pot.
It allow a little more short term power and will help the bass. If youre satisfied with the way that it is now,leave it alone.
oh ok, thanks! hey, can I use 2 1000 uf 35 v caps in series for now for test purposes to see if it helps? wont that give me 2000 uf?
ooo ok , that makes it simpler, I dont have to unsolder the other cap 🙂
so does that mean series devides it in half instead of adding it?
so does that mean series devides it in half instead of adding it?
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