I'm looking at doing the tone control / volume bypass as my first mod. I was wondering if I can implement it with a switch so as to be able to switch from full bypass back to original functionality.
I propose to do this that I would remove c30 and c31. Then go from the input before c30/31 through a pair of caps and into the common of a double pole double throw switch.
Then one side of the switch would land on the other pads where c30/31 had been, hence restoring the circuit to it's original state.
The other side of the switch would land on the right side pads of C20/21, thereby bypassing all of the volume and tone control stage.
The only way this works that I see is if I leave caps c20/21 in place. Will leaving that circuit complete and just landing on the right side of it with my switch work as a volume/tone defeat, or will this cause any problems?
I propose to do this that I would remove c30 and c31. Then go from the input before c30/31 through a pair of caps and into the common of a double pole double throw switch.
Then one side of the switch would land on the other pads where c30/31 had been, hence restoring the circuit to it's original state.
The other side of the switch would land on the right side pads of C20/21, thereby bypassing all of the volume and tone control stage.
The only way this works that I see is if I leave caps c20/21 in place. Will leaving that circuit complete and just landing on the right side of it with my switch work as a volume/tone defeat, or will this cause any problems?
Would be so grateful if you could do this! I'm a noob and just learning. I got the 1/2 watt 22 ohm resistors will these work? They are so big I don't even know how to fit them there.
Lepai TA-2020A+ "Power on/off thump"
First just to be up front with everyone, I’m new to the world of DIY electronics. I did study electronic 20+ years ago, but I am a little rusty now. I just received a new Lepai LP-2020A+ amp. I am currently using a 12V 5A power supply to power it; So far I’m surprise of the "out of the box sound quality”. I do have a very noticeable thump with the power on and off. I am already planning on replacing the large cap (3300uF) with a 5600uF version. While doing that mod I would like to address the thump. Will bypassing the tone and volume control reduce or eliminate the power on/off thump? Are there any other suggestions that may work for the thump?
First just to be up front with everyone, I’m new to the world of DIY electronics. I did study electronic 20+ years ago, but I am a little rusty now. I just received a new Lepai LP-2020A+ amp. I am currently using a 12V 5A power supply to power it; So far I’m surprise of the "out of the box sound quality”. I do have a very noticeable thump with the power on and off. I am already planning on replacing the large cap (3300uF) with a 5600uF version. While doing that mod I would like to address the thump. Will bypassing the tone and volume control reduce or eliminate the power on/off thump? Are there any other suggestions that may work for the thump?
Have Any of you people READ the Wiki?
What is in the Wiki is pretty well ALL that has proven to be worth the effort to do.. by a lot of people over quite some time
Wanna reinvent the wheel using Your superior skills/knowledge.. Fill yer boots trying
.
These are Cheap/crappy circuits.. capable of passable to decent sounds IF modded with Intelligence and prior knowledge. NEVER forget these are ~$15 cheap a** 'amps' no more, no less. Are You.. expecting a Monet .. just lurking in there ??
The Lepai Tone controls are Junk..as they mess up the sound and even worse they are unreliable as Tone controls.. being barely functional.
What is in the Wiki is pretty well ALL that has proven to be worth the effort to do.. by a lot of people over quite some time
Wanna reinvent the wheel using Your superior skills/knowledge.. Fill yer boots trying
.These are Cheap/crappy circuits.. capable of passable to decent sounds IF modded with Intelligence and prior knowledge. NEVER forget these are ~$15 cheap a** 'amps' no more, no less. Are You.. expecting a Monet .. just lurking in there ??
The Lepai Tone controls are Junk..as they mess up the sound and even worse they are unreliable as Tone controls.. being barely functional.
I found that bypassing the op-amps drastically reduced my turn on thump. I strongly suspect the volume op-amp to be the one causing (most of) it.
Have Any of you people READ the Wiki?
What is in the Wiki is pretty well ALL that has proven to be worth the effort to do.. by a lot of people over quite some time
Wanna reinvent the wheel using Your superior skills/knowledge.. Fill yer boots trying
These are Cheap/crappy circuits.. capable of passable to decent sounds IF modded with Intelligence and prior knowledge. NEVER forget these are ~$15 cheap a** 'amps' no more, no less. Are You.. expecting a Monet .. just lurking in there ??
The Lepai Tone controls are Junk..as they mess up the sound and even worse they are unreliable as Tone controls.. being barely functional.
You haven't had anything positive or helpful to add about these amps for some time. All you do is insult people. Why are you still posting?
I bypassed everything but kept my volume pot and I have no turn on thump at all.
Can anyone recommend the best type and sizes caps to use to bypass the tone control circuits? I have also heard that replacing the inductors would help with the overall sound Quality, is so could someone recommend the sizes for them as well. I am going to consider modifying this amp to be my break-in project. Any advice would be greatly appreciated.
.
.
I’m completely new to all this, I did not even know what the hell the wiki thing was. I found it and read it. There are some useful things in it; however the schematic attached to the article does not seem to be an exact match for my version. My red board appears to have different parts than the one shown in the article. Anyway I did some additional leg work and found some parts that may work for the upgrades. If anyone would like to add any comments to the following part list, please do. Thanks.
Output Inductor upgrade:
Mouser P/N 652-RL622-100K-RC Bourns 10uH 3A Inductor tested at 2.52 Mhz
Input power Inductor upgrade:
Mouser P/N 580-19R103C Bourns 10uH 6A Inductor
Bypass Op amp Capacitors
(I have found two choices)
Parts Express P/N 027-415 Dayton Audio Polypropylene 2.2uF 5% 250V
Parts Express P/N 027-916 Janzten Polypropylene 2.2uF 5% 400V
Output Inductor upgrade:
Mouser P/N 652-RL622-100K-RC Bourns 10uH 3A Inductor tested at 2.52 Mhz
Input power Inductor upgrade:
Mouser P/N 580-19R103C Bourns 10uH 6A Inductor
Bypass Op amp Capacitors
(I have found two choices)
Parts Express P/N 027-415 Dayton Audio Polypropylene 2.2uF 5% 250V
Parts Express P/N 027-916 Janzten Polypropylene 2.2uF 5% 400V
Hi,
Have just gone through all the posts and saw these inductors which I have just ordered
@ 10pcs Toroid Inductor 10uH 6A Toroidal Ferrite Core Choke Coil TC33-e3 | eBay
thought you may be interested as they are 10US$.
Best
Have just gone through all the posts and saw these inductors which I have just ordered
@ 10pcs Toroid Inductor 10uH 6A Toroidal Ferrite Core Choke Coil TC33-e3 | eBay
thought you may be interested as they are 10US$.
Best
@blossom, raspberry , dac and ta202à
Hi Blossom,
your config is what I build:
I have an upgraded lepai ta2020 linked to a DAC (from hifimedy) linked to a raspberry.
No hard disk, network use.
Compared to my Denon AVR 1912, sound quality is better, but it feel less 'spacial' : the room is not completly filled by the sound. Maybe a good DSP is requested.
Some tips:
Raspberry pi just improve the firmware to allow DAC working fine.
I am using Raspbian, with mpd, and a cheap chinese tablet as remote.
It works better than XBMC.
USB hub not required for me as hifimedy has its own power supply.
Pros:
cheap, clean, and really really good sound quality.
Cons:
lot of work to do, and battle with my girlfriend.
lot of cables (1 for Dac, 1 for raspberry, 1 for amplifier)
When I bought this simple amp, my goal was to compare it to my Denon AVR 1912, and to know if I will invest in a better home made amp (like IRS 2092).
Conclusion:
I am not desapointed, and I will invest in an IRS 2092.
Total price:
well, ~20$ for lepai, ~20$ for modding.
~35$ for raspberry pi. maybe 10$ for flash card.
$60 for the chinese tablet.
+external DAC.
let say $150~$200 you have a complete and quality good sound system. it is comparable to my AVR1912, but with input sound system with remote tablet.
Hi Blossom,
your config is what I build:
I have an upgraded lepai ta2020 linked to a DAC (from hifimedy) linked to a raspberry.
No hard disk, network use.
Compared to my Denon AVR 1912, sound quality is better, but it feel less 'spacial' : the room is not completly filled by the sound. Maybe a good DSP is requested.
Some tips:
Raspberry pi just improve the firmware to allow DAC working fine.
I am using Raspbian, with mpd, and a cheap chinese tablet as remote.
It works better than XBMC.
USB hub not required for me as hifimedy has its own power supply.
Pros:
cheap, clean, and really really good sound quality.
Cons:
lot of work to do, and battle with my girlfriend.
lot of cables (1 for Dac, 1 for raspberry, 1 for amplifier)
When I bought this simple amp, my goal was to compare it to my Denon AVR 1912, and to know if I will invest in a better home made amp (like IRS 2092).
Conclusion:
I am not desapointed, and I will invest in an IRS 2092.
Total price:
well, ~20$ for lepai, ~20$ for modding.
~35$ for raspberry pi. maybe 10$ for flash card.
$60 for the chinese tablet.
+external DAC.
let say $150~$200 you have a complete and quality good sound system. it is comparable to my AVR1912, but with input sound system with remote tablet.
Simple question here, but how do we remove the knobs on the lepai face without breaking them? I think I have the more recent model.
I'm asking because I want to fix my lepai into a 5.25in bay in my pc case to reduce clutter. (and then somehow deal with an extra power cord power supply snaking out of it)
I'm asking because I want to fix my lepai into a 5.25in bay in my pc case to reduce clutter. (and then somehow deal with an extra power cord power supply snaking out of it)
Hey everyone,
New member, been lurking for a while. Completely new to the diy audio scene, so cut me some slack.
My question is:
I got a good deal on logitech z623 2.1 system, an I was wondering is it worth connecting the lepai 2020A+ amp to it. I want to hook everything up to my laptop, but don't know what cables should i get/how to connect them.
Thank you,
-shark
New member, been lurking for a while. Completely new to the diy audio scene, so cut me some slack.
My question is:
I got a good deal on logitech z623 2.1 system, an I was wondering is it worth connecting the lepai 2020A+ amp to it. I want to hook everything up to my laptop, but don't know what cables should i get/how to connect them.
Thank you,
-shark
Should be able to get a small flat underneath them and lever off, they are a bit tight but no way tight enough to break them. Having removed the volume know you will need to then unscrew the nut holding the plastic on and will also need to unsolder the power switch before you can remove the front plate. Should be no more than 5mins for the whole disassemble if the iron is hot. As to power supply do you have a spare PCI slot? If so could mount a the female end of a DC extension lead on the blank and then run to the amp inside the case.
I want to add a "clip" (not "fault") LED to the LP2020, but have not found an actual circuit. Has anybody done it? What is not clear to me is whether the OVERLOADB pin on the TA2020 goes high when there is no fault, or does it float? The chip's doc only says that it is "5V logic" and goes low when there is an overload. If it normally goes high, I'm thinking of a circuit like this:
OVERLOADB -> 5K resistor -> base of an NPN bipolar transistor. The Emitter to ground. The collector to the positive end of one of the diodes that lights up the volume knob, between the LED and the resistor the supplies it with power. (Can also replace the LED with a red one. And can also add more resistance to that supply line to reduce the LED current somewhat.) The idea is that normally (when there is no overload) the transistor will be driven to conduct and bypass the LED so it will not light up. But that depends on that OVERLOADB pin going high normally. If that's not the case then a more complicated circuit would be needed. If that pin is an open collector, can it take 12V when open-circuit?
OVERLOADB -> 5K resistor -> base of an NPN bipolar transistor. The Emitter to ground. The collector to the positive end of one of the diodes that lights up the volume knob, between the LED and the resistor the supplies it with power. (Can also replace the LED with a red one. And can also add more resistance to that supply line to reduce the LED current somewhat.) The idea is that normally (when there is no overload) the transistor will be driven to conduct and bypass the LED so it will not light up. But that depends on that OVERLOADB pin going high normally. If that's not the case then a more complicated circuit would be needed. If that pin is an open collector, can it take 12V when open-circuit?
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