Weird, but I guess it seems to stop turn on thump when I tested it out...Bone said:Yes because the "power" switch doesnt switch the power it off just mutes the 2020
Tony
I guess I may be able to just use a PSU with a switch for now.
To echo what other people have said, it does sound pretty nice straight out the box, I'm tempted to order a 2nd one just so I can try modding one and then see how the sound of the unmodded one compares...
BYPASSING OPAMP AND TONE CONTROLS
I'm playing with some of these Lepai for some friends. If in the stock form they sound good, after a couple of little mods the improving is really stunning.
Please allow a burn in period (around 100 hours) for the best sound (the bass become fuller and warmer).
About bypassing opamp and tone controls:
-replace first input capacitors with some good film cap (2,2uF up to 4,7uF: the bigger the capacitor the bigger the 'bump' when switching on the amp);
-replace input resistors with 20/22k;
-connect one side of the new input capacitors with one side of new input resistors.
ET VOILA'.
I'm playing with some of these Lepai for some friends. If in the stock form they sound good, after a couple of little mods the improving is really stunning.
Please allow a burn in period (around 100 hours) for the best sound (the bass become fuller and warmer).
About bypassing opamp and tone controls:
-replace first input capacitors with some good film cap (2,2uF up to 4,7uF: the bigger the capacitor the bigger the 'bump' when switching on the amp);
-replace input resistors with 20/22k;
-connect one side of the new input capacitors with one side of new input resistors.
ET VOILA'.
Attachments
I was wondering how the op-amp is powered on this? I was thinking if it's from a rail splitter, would it be able to power 2 op-amp IC's ? I ask because this would make an ideal unit to use for bi-amping as you could also have an active crossover in the unit also with a few extra components...
Calamaro: excellent, info thanks, I'll have to try the mods and see how they turn out, especially the tone control bypass mod.
I guess if you had a dual gang switch and some extra wires, you could then disable/enable the tone control if you needed to?
Calamaro: excellent, info thanks, I'll have to try the mods and see how they turn out, especially the tone control bypass mod.
I guess if you had a dual gang switch and some extra wires, you could then disable/enable the tone control if you needed to?
New Inductors
I just replaced the inductors. Got a set of wire-your-own toroids from 41hz. I had to change the heatsink for a slightly smaller one to make space.
photo not so good, will put up another one when i get time.
http://pix.minirig.org.au/main.php?g2_itemId=1039
removed the inductor from the power supply too, replaced it with a ferrite bead, thanks Calamaro
col.
I just replaced the inductors. Got a set of wire-your-own toroids from 41hz. I had to change the heatsink for a slightly smaller one to make space.
photo not so good, will put up another one when i get time.
http://pix.minirig.org.au/main.php?g2_itemId=1039
removed the inductor from the power supply too, replaced it with a ferrite bead, thanks Calamaro
col.
What gains are there to be had swapping output inductors?
I know on the sure class d modules the output inductors were apparently causing background noise, but I find on my module that even when you put your ear close to the speaker you can barely hear and hiss...
What other benefits does swapping output inductors give? Does it sound much different compared to the stock inductors?
I know on the sure class d modules the output inductors were apparently causing background noise, but I find on my module that even when you put your ear close to the speaker you can barely hear and hiss...
What other benefits does swapping output inductors give? Does it sound much different compared to the stock inductors?
Output Inductors
I measured the stock output inductors with my Dayton Woofer Tester 3 and they measured at around 9uH, they are tiny with very thin wire. I don't believe that these are anywhere near capable of handling 3A as specified in the TA2020 datasheet.
I also think the resistance of the thin wire is probably high. I'm not sure if the same laws apply as inductors in passive speaker crossovers but usually thin wire has an impact on bass reproduction. The 41hz amp6 inductors have thick wire and are capable of handling 5A! After I wound them I checked them with WT3 and they measured in at 10.02uH
Once I fitted them in the Lepai and tested, immediately I had to turn down the bass, before I had the bass tone control on 3/4 I had to back it off to 1/2
I think if you bypassing the tone controls you have even more to gain from replacing the inductors as the amp frequency response is not very flat and tails off in the lower frequencies.
I also changed the outer 2 mylar caps. They were 47nF. I have changed them to 22nF which is inline with the more recent TA2020 datasheet (the older one specifies 47nF I think).
My filters are now the same as a 41hz amp6.
A better photo:
http://pix.minirig.org.au/main.php?g2_itemId=1045
col.
I measured the stock output inductors with my Dayton Woofer Tester 3 and they measured at around 9uH, they are tiny with very thin wire. I don't believe that these are anywhere near capable of handling 3A as specified in the TA2020 datasheet.
I also think the resistance of the thin wire is probably high. I'm not sure if the same laws apply as inductors in passive speaker crossovers but usually thin wire has an impact on bass reproduction. The 41hz amp6 inductors have thick wire and are capable of handling 5A! After I wound them I checked them with WT3 and they measured in at 10.02uH
Once I fitted them in the Lepai and tested, immediately I had to turn down the bass, before I had the bass tone control on 3/4 I had to back it off to 1/2
I think if you bypassing the tone controls you have even more to gain from replacing the inductors as the amp frequency response is not very flat and tails off in the lower frequencies.
I also changed the outer 2 mylar caps. They were 47nF. I have changed them to 22nF which is inline with the more recent TA2020 datasheet (the older one specifies 47nF I think).
My filters are now the same as a 41hz amp6.
A better photo:
http://pix.minirig.org.au/main.php?g2_itemId=1045
col.
Boosting the power supply
I have a few laptop SMPS that are all around 19-22v 3-4A . For them to work with the Lepai the voltage needs to be max around 13.3v, so a step-down regulator is required. I purchased a few LM338T that were on special and have built a variable regulator circuit from the data sheet examples and by looking at a siliconchip project. It has a trimmer for setting the output voltage.
http://pix.minirig.org.au/main.php?g2_itemId=1054
http://pix.minirig.org.au/main.php?g2_itemId=1057
I'm still testing, trying with different components but it has already made quite a difference from my 12v SMPS.
col.
I have a few laptop SMPS that are all around 19-22v 3-4A . For them to work with the Lepai the voltage needs to be max around 13.3v, so a step-down regulator is required. I purchased a few LM338T that were on special and have built a variable regulator circuit from the data sheet examples and by looking at a siliconchip project. It has a trimmer for setting the output voltage.
http://pix.minirig.org.au/main.php?g2_itemId=1054
http://pix.minirig.org.au/main.php?g2_itemId=1057
I'm still testing, trying with different components but it has already made quite a difference from my 12v SMPS.
col.
Re: Output Inductors
you use a toroid to wind the inductor and where you get them in melb.?
thanks
col said:I measured the stock output inductors with my Dayton Woofer Tester 3 and they measured at around 9uH, they are tiny with very thin wire. I don't believe that these are anywhere near capable of handling 3A as specified in the TA2020 datasheet.
I also think the resistance of the thin wire is probably high. I'm not sure if the same laws apply as inductors in passive speaker crossovers but usually thin wire has an impact on bass reproduction. The 41hz amp6 inductors have thick wire and are capable of handling 5A! After I wound them I checked them with WT3 and they measured in at 10.02uH
Once I fitted them in the Lepai and tested, immediately I had to turn down the bass, before I had the bass tone control on 3/4 I had to back it off to 1/2
My filters are now the same as a 41hz amp6.
A better photo:
http://pix.minirig.org.au/main.php?g2_itemId=1045
col.
you use a toroid to wind the inductor and where you get them in melb.?
thanks
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