I seem to always have enough power, but I like more power 😀
Are the Niles modules "audiophile" quality? SI-1230 or zr-4630
Or worth it to make a bridged amp out of?
I think I have a transformer for the Niles modules, that's why I ask about them.
35v x 2 -- 750 VA
Are they easy to wire up?
Other option is Brian GT (single) LM3875 stereo chipamp kit. I built one of these years ago. Sounded great.
I seem to always have an issue with too more power coming from an amp. As in, I use the attenuator way at the bottom of it's range and fine adjustments are hard.
The Brian GT amp was like this (not enough attenuation ability) and my current NAD envelope 2100 is also; I can't adjust it low enough a lot of the time.
Basically I want more power of 2 - LM3886 chips bridged, but I DO NOT want to do it if it's not "audiophile" quality or if it's complex to wire up or figure out how to wire it up.
Are the Niles modules "audiophile" quality? SI-1230 or zr-4630
Or worth it to make a bridged amp out of?
I think I have a transformer for the Niles modules, that's why I ask about them.
35v x 2 -- 750 VA
Are they easy to wire up?
Other option is Brian GT (single) LM3875 stereo chipamp kit. I built one of these years ago. Sounded great.
I seem to always have an issue with too more power coming from an amp. As in, I use the attenuator way at the bottom of it's range and fine adjustments are hard.
The Brian GT amp was like this (not enough attenuation ability) and my current NAD envelope 2100 is also; I can't adjust it low enough a lot of the time.
Basically I want more power of 2 - LM3886 chips bridged, but I DO NOT want to do it if it's not "audiophile" quality or if it's complex to wire up or figure out how to wire it up.
I'm starting to solder the BrianGT boards together.
I have a:
LM3875 stereo kit.
and
LM3886TF dual mono kit (I think it's dual mono).
I'll post links here.
http://diyaudioprojects.com/Chip/LM3886_CA/lm3886-manual.pdf
LM3886 Gainclone Chip-amp Amplifier Construction Project
DIY Audio Electronics from Zynsonix.com: BrianGT LM3886 Chipamp aka Gainclone Amplifier
I try to use pics to get the boards together.
I have a:
LM3875 stereo kit.
and
LM3886TF dual mono kit (I think it's dual mono).
I'll post links here.
http://diyaudioprojects.com/Chip/LM3886_CA/lm3886-manual.pdf
LM3886 Gainclone Chip-amp Amplifier Construction Project
DIY Audio Electronics from Zynsonix.com: BrianGT LM3886 Chipamp aka Gainclone Amplifier
I try to use pics to get the boards together.
Do the boards/resistors this look right?
I couldn't see the "Rm" resistor in any pics?
Actually I went with the process of elimination on the bottom resistor on the power supply board also, but it was less resistors and they were much easier to see.
Which configuration should I use?:
Feedback capacitor or no feedback capacitor?
Why would I need lower DC offset?
I just want it to be functionally optimum.
One more link:
A pair of LM3886s | Two channels of an LM3886 chip amplifier… | Flickr
Wow, I can see the resistors way better in my pics (especially when zoomed in) than I can with my naked eye.
I couldn't see the "Rm" resistor in any pics?
Actually I went with the process of elimination on the bottom resistor on the power supply board also, but it was less resistors and they were much easier to see.
Which configuration should I use?:
Feedback capacitor or no feedback capacitor?
Why would I need lower DC offset?
I just want it to be functionally optimum.
One more link:
A pair of LM3886s | Two channels of an LM3886 chip amplifier… | Flickr
Wow, I can see the resistors way better in my pics (especially when zoomed in) than I can with my naked eye.
Attachments
Everything looks fine! For bleeder 2.2k is quite low, 4.7k-5.6k better. If you can ensure that earlier stage will never have output dc offset than & only then you can skip feedback cap. Also add a low pass RF filtering stage before non-inverting input using 1k resistor & 680pf ceramic. btw are you going to use 35-0-35v transformer? that's dangerous!! 
Okay, so I will use the feedback cap.
I don't know what a bleeder is.
I don't know how to add that RF filtering.
I'm using a kit.
Can I unwind the 35v transformer to 25v?
I need 2 - 25v pairs though.
Not sure I have something like that.
I don't know what a bleeder is.
I don't know how to add that RF filtering.
I'm using a kit.
Can I unwind the 35v transformer to 25v?
I need 2 - 25v pairs though.
Not sure I have something like that.
Congratulations!
1)Check the backside of the PSU boards, upgrade those resistor(bleeder) to 4.7kohm 2watt. But you can leave that as it is.
2)A low pass filter before the non-inv input is a very good idea to filter out RF garbage(radio frequencies). Follow the attachment....solder 680pf ceramic capacitor after R1 & in parallel with R2.
3)For RM use 33kohm resistor & for CM 100uf electrolytic for larger turn on delay.
What do you mean by 35v? 17.5v-0-17.5v secondary? You need a CT or dual secondary type transformer for symmetrical PSU. For common load impedances like between 4-8ohm load the recommended transformer voltage is 22-0-22v. Btw for stereo monoblock you need two transformer & two PSU board.
Attachments
I unwound too much wire and got down to 21 VDC. Should I leave it or add some wire back? I have 8ohm passive speakers (woofer and mid are 8 ohm). Tweeter is 4 ohm nominal impedance.
1)Sorry, no more advice from me. Do whatever you wish. 2)For 8ohm nominal load impedance the recommended supply voltage is +/-35vDC & for 4ohm load +/-30vDC Max.
Thank you for the help.
From reading I got this:
35v the the boards for 8 ohm (nominal impedance I assume?)
28-28.5v is what I read for 4 ohm (nominal impedance I assume?)
But some people do 18v some do 25v.
Some one made the argument of 18v because: what good is an amp that does 68watt at 8 ohm if you cannot run 4ohm speaker on it? Which I kind of agree with. Also he said: don't strain the chip , which I also like.
The PDF states 18v-22v for the tranformer.
I have 4 ohm tweeter, 8 ohm mid and 8 ohm 10" woofer Dayton RS270S for now.
From reading on the DIY audio forum, 10-20 people said it was okay to unwind a transformer.
1-2 people said don't do it.
One guy stated something about leakage, etc. if you unwind.
750w for 2 50w channels? Way way too much ! That’s one of the reasons you shouldn’t unwind that transformer.
I think I need the AMPower AM2000 chassis in the link:
LM3886 Gainclone Chip-amp Amplifier Construction Project
It's made in Australia. It looks super well built, which I like. I really haven't seen anything mass-produced made that well.
I guess I will try to find a way to cram my amp inside the tiny chassis I have. And maybe get a smaller torroidal transformer in the end.
LM3886 Gainclone Chip-amp Amplifier Construction Project
It's made in Australia. It looks super well built, which I like. I really haven't seen anything mass-produced made that well.
I guess I will try to find a way to cram my amp inside the tiny chassis I have. And maybe get a smaller torroidal transformer in the end.