Suggestions for a chip amp Kit or Project?

santiu · 12th November 2005, 02:08 AM

Hey guys. So I've got a busted NAD amp. Anyhow, I wanted to steal the power transformer from it to use in a chip amp (and any other parts I can yank from it). I've been into building speakers, but I've never messed with amps before (although I have a good background with electronics and micro-controllers)

I plan to use the amp to power a pair of dipole woofers.

Any suggestions for a good kit or a well documented project I can follow? Budget is very important.

thanks a bunch!

hongrn · 12th November 2005, 03:04 AM

I just finished a LM4780 from a kit, but you should really check out Nuuk's site right here and build the LM3886.

Hong

Decibel Dungeon

rudi · 12th November 2005, 06:05 AM

this amp design is the best out of all of them
http://www.diyaudio.com/forums/showt...507#post609507

you will most probably use it as you main amp, but the bass is really good on this one.

and you can buy the PCB at http://www.twistedpearaudio.com/

the best for Bass is still the digital amps. look at www.41hz.com and check out amp2. there is NOTHING that will beat the tight bass on this one, and it is very powerfull

santiu · 12th November 2005, 03:29 PM

hongrn, the LM3886 project looks cheap and easy. Will it have enough power? It will be driving an 8ohm load. What do think about his buffer stages? Would it be advisable to use one on the LM3886?

rudi, wow, those amps look great! However, they are both a bit more than I wanted to spend (sorry for not specifying that first). I was hoping to try to keep it under $50. However, it looks like on both kits you get a lot of bang for the price, so I might stretch on this one.

To be perfectly honest, I don't know how much power I need. However, while currently it will only drive an 8ohm load, it would be nice to be able to drive a 4ohm load should I change my setup in the future (which it looks like both of these kits/projects do).

Just to give you more info on how it's all being used, this amp part of a tri-amped Linkwitz based system I'm putting together. Like I said before, this amp will be used to power a pair of dipole woofers. I've already got a K-12M tube kit in the mail that will power the mids, and I'm still in the process of deciding what to use to power the tweets. I'm thinking it's going to be some simple single ended valve amp.

Oh, and how do I tell what my transformer puts out. The only markings I see on it with numbers is: NPT-1864S. I'm thinking of buying a repair manual for this thing anyways, so i can better understand what's going on inside, and make use of as many good parts as possible.

Thanks again for the suggestions so far, and if you have any more keep 'em coming

joensd · 12th November 2005, 03:45 PM

Quote:

Will it have enough power? It will be driving an 8ohm load

You can check out Nationals little calculator sheet (if you can load xls-files):
http://www.national.com/appinfo/audi...gn_Guide13.xls
For an 8ohm load I´d go with 20-24VAV secondaries so you end up with roughly +-28-35DC rails.
Now if you want it more versatile (4ohm loads) make a compromise
and choose lower secondaries so the dissipation doesn´t get too high and the protection doesn´t kick in.(18-20V secondaries)
Just plug the numbers into the calculator and you´ll see what I mean.

greets
Jens
PS.: Just curious what you think about it : what´s a good start into micro-controllers? A PIC with appropriate software?

Nordic · 12th November 2005, 04:06 PM

If its money you want to save build one of Nuuk's basic inverted GCs, useing the LM3875 only marginaly less powerfull.
I have built this one myself, and its realy good.

Needs
1x LM3875
2x 1000ufd electr.
2x .1ufd ceramic or polypropelene if the budget alows
1x 2.2ufd bi(non)-polar cap
1x 10k .25W
1x 220k .5W
1x heatsink

Rod Elliot PSU
1x 2x24v trafo
2x rectifier bridges capable of handling 5A each
4x 10000ufd caps
2x 5A diodes
1x 10ohm 1W

This is from memory, but I'm pretty sure it includes everything but the box.

12th November 2005, 02:08 AM	#1
santiu diyAudio Member Join Date: Feb 2005 Location: Los Angeles	Suggestions for a chip amp Kit or Project? Hey guys. So I've got a busted NAD amp. Anyhow, I wanted to steal the power transformer from it to use in a chip amp (and any other parts I can yank from it). I've been into building speakers, but I've never messed with amps before (although I have a good background with electronics and micro-controllers) I plan to use the amp to power a pair of dipole woofers. Any suggestions for a good kit or a well documented project I can follow? Budget is very important. thanks a bunch!

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12th November 2005, 03:04 AM	#2
hongrn diyAudio Member Join Date: Mar 2005 Location: Placentia, CA, USA	I just finished a LM4780 from a kit, but you should really check out Nuuk's site right here and build the LM3886. Hong Decibel Dungeon

12th November 2005, 06:05 AM	#3
rudi diyAudio Member Join Date: Jul 2004 Location: .	this amp design is the best out of all of them http://www.diyaudio.com/forums/showt...507#post609507 you will most probably use it as you main amp, but the bass is really good on this one. and you can buy the PCB at http://www.twistedpearaudio.com/ the best for Bass is still the digital amps. look at www.41hz.com and check out amp2. there is NOTHING that will beat the tight bass on this one, and it is very powerfull

12th November 2005, 03:29 PM	#4
santiu diyAudio Member Join Date: Feb 2005 Location: Los Angeles	hongrn, the LM3886 project looks cheap and easy. Will it have enough power? It will be driving an 8ohm load. What do think about his buffer stages? Would it be advisable to use one on the LM3886? rudi, wow, those amps look great! However, they are both a bit more than I wanted to spend (sorry for not specifying that first). I was hoping to try to keep it under $50. However, it looks like on both kits you get a lot of bang for the price, so I might stretch on this one. To be perfectly honest, I don't know how much power I need. However, while currently it will only drive an 8ohm load, it would be nice to be able to drive a 4ohm load should I change my setup in the future (which it looks like both of these kits/projects do). Just to give you more info on how it's all being used, this amp part of a tri-amped Linkwitz based system I'm putting together. Like I said before, this amp will be used to power a pair of dipole woofers. I've already got a K-12M tube kit in the mail that will power the mids, and I'm still in the process of deciding what to use to power the tweets. I'm thinking it's going to be some simple single ended valve amp. Oh, and how do I tell what my transformer puts out. The only markings I see on it with numbers is: NPT-1864S. I'm thinking of buying a repair manual for this thing anyways, so i can better understand what's going on inside, and make use of as many good parts as possible. Thanks again for the suggestions so far, and if you have any more keep 'em coming

12th November 2005, 04:06 PM	#6
Nordic diyAudio Member Join Date: Sep 2005	If its money you want to save build one of Nuuk's basic inverted GCs, useing the LM3875 only marginaly less powerfull. I have built this one myself, and its realy good. Needs 1x LM3875 2x 1000ufd electr. 2x .1ufd ceramic or polypropelene if the budget alows 1x 2.2ufd bi(non)-polar cap 1x 10k .25W 1x 220k .5W 1x heatsink Rod Elliot PSU 1x 2x24v trafo 2x rectifier bridges capable of handling 5A each 4x 10000ufd caps 2x 5A diodes 1x 10ohm 1W This is from memory, but I'm pretty sure it includes everything but the box.