I completed my first Velleman chipamp this afternoon. I'm pretty impressed by the sound of it. I bought it through Parts Express and the whole thing cost a little less than $60. I have a $40 volume and tone control kit on order to complete this project. Then comes the case. I've got some nice wood scraps and some pieces of anodized steel in my garage that will work perfect for a case.
I used some speakers from a Packard Bell tube stereo console I picked up at a second-hand store. They need a little tweaking, but they're not bad.
All in all, I didn't know what to expect from an inexpensive little kit with minimal parts. However, I think I'll be doing some more chip amp kits, or looking for tweaks for this one. I'm pretty impressed by the output of this little guy. I'm looking forward to building the volume and tone control kit and seeing how much it adds to the amp.
This kit is the Velleman K4003. I'll be adding a Velleman K8084 for the volume and tone control.
I'm new to this stuff, so I hope I can get a few pointers. Do any of you DIY-ers have any suggestions for tweaks? Better caps, maybe??? Can anyone offer a quick explanation of how this thing works, beyond the rectifier.
I have a power switch to add, and I have a question about that. What do I need to do to keep the amp from "popping" when I turn it on?
Again, any advice will be greatly appreciated!
Thanks,
Mike
I used some speakers from a Packard Bell tube stereo console I picked up at a second-hand store. They need a little tweaking, but they're not bad.
All in all, I didn't know what to expect from an inexpensive little kit with minimal parts. However, I think I'll be doing some more chip amp kits, or looking for tweaks for this one. I'm pretty impressed by the output of this little guy. I'm looking forward to building the volume and tone control kit and seeing how much it adds to the amp.
This kit is the Velleman K4003. I'll be adding a Velleman K8084 for the volume and tone control.
I'm new to this stuff, so I hope I can get a few pointers. Do any of you DIY-ers have any suggestions for tweaks? Better caps, maybe??? Can anyone offer a quick explanation of how this thing works, beyond the rectifier.
I have a power switch to add, and I have a question about that. What do I need to do to keep the amp from "popping" when I turn it on?
Again, any advice will be greatly appreciated!
Thanks,
Mike
Attachments
Well, I got the Velleman volume and tone control kit in the mail today and got it assembled. I don't know if this will work without the schematic, but I'll ask anyway. I was told by Skip at PE that I can wire both of the boards, which each use 12-0-12, off the same center tapped transformer. Can anyone shed some light on this? 
I can call Skip tomorrow, but I'm kind of anxious to try this out. I built some 3CR Tangbands that I'd like to hook-up to this amp, so I'm a little antsy.With that being said, I'm not in such a hurry that I'll risk damage to either of my projects. Thanks again all!
Mike
I can call Skip tomorrow, but I'm kind of anxious to try this out. I built some 3CR Tangbands that I'd like to hook-up to this amp, so I'm a little antsy.With that being said, I'm not in such a hurry that I'll risk damage to either of my projects. Thanks again all!Mike
I think you can overcome the clicks by using the onboard mute function.... it would be a resitor to the mute pin that brings the current down to the amount needed to trigger it...
the resitor will go through a relay with the resitor connected so that it is in circuit while the relay is "off"... on the coil side of the relay slap a small electrolitic in parallel... and one resistor in the line going to the coil, to slowly charge up the capacitor for a second or two...
the capacitor acts like a short circuit until it is charged up to voltage.
So when you power on the capacitor starts charging, but does not allow the power to get to the relay coil... during this time the resistor you set up in the first step is receiving voltage and provding the current needed to keep the mute function on.
When the capacitor is charged, the relay will switch and the resitor powering the mute pin will be disconncted form the power source...
RE HUM
Do you get the hum trough your amp only or is it also there if you connect a speaker or headphone to your preamp ?
Can you tell us how you made the power supply of the premap... intersted in how you split the rails or if you are just useing a single ended supply...
I think it is totaly solveable... in fact I have never been able to make a cmoy hum...
I have a few things in mind that could probably fall together to form hum as a total system ( amp + pre+source).
I would start with only one input connected, bring the circuit down to its most basic implementation. Fix the hum problem, now start addingthe other channels... compare mains powered sources to something like an ipod source etc.... see if hum stays the same...
the resitor will go through a relay with the resitor connected so that it is in circuit while the relay is "off"... on the coil side of the relay slap a small electrolitic in parallel... and one resistor in the line going to the coil, to slowly charge up the capacitor for a second or two...
the capacitor acts like a short circuit until it is charged up to voltage.
So when you power on the capacitor starts charging, but does not allow the power to get to the relay coil... during this time the resistor you set up in the first step is receiving voltage and provding the current needed to keep the mute function on.
When the capacitor is charged, the relay will switch and the resitor powering the mute pin will be disconncted form the power source...
RE HUM
Do you get the hum trough your amp only or is it also there if you connect a speaker or headphone to your preamp ?
Can you tell us how you made the power supply of the premap... intersted in how you split the rails or if you are just useing a single ended supply...
I think it is totaly solveable... in fact I have never been able to make a cmoy hum...
I have a few things in mind that could probably fall together to form hum as a total system ( amp + pre+source).
I would start with only one input connected, bring the circuit down to its most basic implementation. Fix the hum problem, now start addingthe other channels... compare mains powered sources to something like an ipod source etc.... see if hum stays the same...
mikje said:
A simple tweak for the preamp board would be better dual op-amps; as they're socketed it's easy to experiment. Apparently they come with TL072, it's not expensive to buy a few more up-market ones to try without going OTT. NE5532 and OPA2134 spring to mind but others may suggest better.
Both these boards use a simple onboard rectifier/smoothing section so on one hand changes to the electrolytics is pretty easy, on the other bypassing this section on the preamp with a regulated (7812 & 7912) supply may give more benefit.
Full preamp details.
K4003 Amp details.
cpemma,
Thanks for the tips. I found the op amps and regulators at mcmelectronics. Can you explain for this newbie how I would wire the regulator. Also, if I replaced the electrolytics, what would you recommend I use to replace them. What effect on the sound will better, larger electroytics have?
Thanks again for your tips.
Mike
Thanks for the tips. I found the op amps and regulators at mcmelectronics. Can you explain for this newbie how I would wire the regulator. Also, if I replaced the electrolytics, what would you recommend I use to replace them. What effect on the sound will better, larger electroytics have?
Thanks again for your tips.
Mike
Bluto,
I have been running the 3CRs. I like them a lot. They are light in the base, so I run them with a sub-woofer. I ran them off my Velleman amp; 12-15 WPC. They sounded great. Definitely worth the time and money. They take a little time to break in, so that needs to be kept in mind.
Thanks for asking.
Mike
I have been running the 3CRs. I like them a lot. They are light in the base, so I run them with a sub-woofer. I ran them off my Velleman amp; 12-15 WPC. They sounded great. Definitely worth the time and money. They take a little time to break in, so that needs to be kept in mind.
Thanks for asking.
Mike
I think I'm being close to finished with this amp. I still have a very slight hum, so I still need to work on some grounding. Otherwise, I think it's finished!
http://www.audiocircle.com/gallery/thumbnails.php?album=2191
http://www.audiocircle.com/gallery/thumbnails.php?album=2191
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