Cheers, I had a bit of spare time over the weekend, ideal soldering time. 🙂Calamaro said:
I've checked the bottom of both boards, and the boards themselves appear to be identical, there are only changes around the switch area where a trace is cut and another connection bridged with wire on my original (modded) amp.
Nice mods Mike. Not sure about the 2p coin though. I think it's illegal to drill holes in coins of the Queens realm 
What did you end up doing with the Inductors? Can't see them from your photos.Can you upload a shot of the rear panel?
I think your new Lepai is similar to the last two that have arrived here. I notice that yours have polyester/MKT output filter caps. Looking at the MK1, I think that is how they started off. I thought all the MK2-3s had Mylar though.
The power switch / Mute switch has been re-routed. It now turns off the power. The start up pop happens on both versions. Iv'e reduced mine a lot by replacing all the 10uF caps for 2.2uF but there is still a small "pop".
Any joy with the tone controls detent switch? I'm waiting on you leading the way with that one.
col.
What did you end up doing with the Inductors? Can't see them from your photos.Can you upload a shot of the rear panel?
I think your new Lepai is similar to the last two that have arrived here. I notice that yours have polyester/MKT output filter caps. Looking at the MK1, I think that is how they started off. I thought all the MK2-3s had Mylar though.
The power switch / Mute switch has been re-routed. It now turns off the power. The start up pop happens on both versions. Iv'e reduced mine a lot by replacing all the 10uF caps for 2.2uF but there is still a small "pop".
Any joy with the tone controls detent switch? I'm waiting on you leading the way with that one.
col.
I hope I don't get busted for treason! 😱col said:Nice mods Mike. Not sure about the 2p coin though. I think it's illegal to drill holes in coins of the Queens realm
I'm still using the stock inductors right now, I've put an order in at RS and am waiting for some higher current ones to arrive.col said:
Here's a shot of the back panel:
An externally hosted image should be here but it was not working when we last tested it.
It's not a work of art but I was happy to have something better than the stock connectors...
I'm glad I've got one of each version, at least I now know the differences... I think I'll try swapping out the 10uF caps as when the amp is turned on it really makes my speaker cones move a lot. 😱col said:
As for the tone overrride switch, I thought I had a DPDT switch but it turned out to be SPDT so I've now ordered a DPDT and am waiting for it to arrive. It shouldn't be too hard tho, I'm thinking I may be able to use wires straight from the volume pot, as my volume pot is already hovering above the PCB...
I plan to have the 2 wires from the middle volume pot pins go to to the center 2 wires on the DPDT switch.
I'll then have out 2 wires on the switch go to the PCB were the volume pot wires should go, so when the switch is in one position it well work as normal, but I will have 2 more wires going after the op-amp but before the cap and resistor before the audio in pins on the Tripath chip... This way the switch in the other position should put the output from the volume pot straight to the TA2020 (cap and resistor)...
I'm not 100% sure if this will work but it should do in theory... As soon as I make some progress I'll be sure to post my findings. 🙂
qingcai said:
Qingcai,
There are many fake components in China. Have you seen the ceramic capacitor with MKT casing? 😱
Anyway, listening is believing.
tone control bypass mod
tone control bypass mod works
you need to follow along from pins 10 and 13, they should lead to a 20k resistor. Follow the 20 resistor, this should lead to a to a 2.2uF cap.
Unsolder the 2.2uF cap, and solder some wires in the PCB holes the cap came from.
Now, the shaded side is the signal from the op-amp, and the non-shaded side goes to the TA2020 input pins.
solder the wire from the shaded side to one of your switch terminals, so that then the switch is in this position, you will hear the signal from the op-amp.
Now, for the other wire, you need to solder this to the centre (switched) pin on your switch, and you still meed to have the 2.2uF cap inline also, I soldered the cap straight to the switch, then ran a wire from the cap to the PCB:
Now, you should have one last pin on your switch, wire this up to the centre pin on the volume pot.
I did one channel at a time, this way you can make sure L & R do not get swapped over then you switch.
Here's both channels modded:
Sorry for the out of focus pics, I only had a camera phone to hand... 😱
Thoughts, sounds nice, I tried to match the bass and treble with the knobs to the bypassed signal, and you can definitely hear that the JRC4558 is not a nice op-amp! 🙂
EDIT: Feel free to replace the 2.2uF electrolytic caps with something a little nicer if you have it to hand. I stuck with the electrolytics as this was all I had!
tone control bypass mod works
you need to follow along from pins 10 and 13, they should lead to a 20k resistor. Follow the 20 resistor, this should lead to a to a 2.2uF cap.
Unsolder the 2.2uF cap, and solder some wires in the PCB holes the cap came from.
Now, the shaded side is the signal from the op-amp, and the non-shaded side goes to the TA2020 input pins.
solder the wire from the shaded side to one of your switch terminals, so that then the switch is in this position, you will hear the signal from the op-amp.
Now, for the other wire, you need to solder this to the centre (switched) pin on your switch, and you still meed to have the 2.2uF cap inline also, I soldered the cap straight to the switch, then ran a wire from the cap to the PCB:
An externally hosted image should be here but it was not working when we last tested it.
Now, you should have one last pin on your switch, wire this up to the centre pin on the volume pot.
I did one channel at a time, this way you can make sure L & R do not get swapped over then you switch.
Here's both channels modded:
An externally hosted image should be here but it was not working when we last tested it.
Sorry for the out of focus pics, I only had a camera phone to hand... 😱
Thoughts, sounds nice, I tried to match the bass and treble with the knobs to the bypassed signal, and you can definitely hear that the JRC4558 is not a nice op-amp! 🙂
EDIT: Feel free to replace the 2.2uF electrolytic caps with something a little nicer if you have it to hand. I stuck with the electrolytics as this was all I had!
excellent! Will have a go at it on mine when i get a chance and find a suitable switch.
The opamp is the least of your worries. The resistors in the tone control are not matched and they feed into bad quality dual-gang pots that are inaccurate, the capacitors are not matched either and are the wrong values and of the cheap ceramic variety. This leads to the 2 channels going all out of sync as they pass through the tone control section. What a mess!
There is a lot to be gained by cleaning all this up, more than just simply swaping out the opamp. You need to match up the resistor pairs with 1% 1/2W metal film, then change the pots for something better and match up some MKTs of the right value. If you do this and get the stereo signal passing through the tone control in sync then swap out the opamp it will sing! (mine does 🙂
col.
I'll try and grab some better pics of mine next time I have it apart, once you find the 2 caps to de-solder it's pretty easy from that point on. 🙂 It works just like a source selector switch really, with only 2 sources (volume pot and op-amp).col said:
EDIT: I hope you don't mind, I couldn't find a decent pic of the top of the amp so I pinched one from your minirig page! 😱 I've circled the caps that need removing:
An externally hosted image should be here but it was not working when we last tested it.
Well that does explain why I can hear such a difference when using that bypass switch! 😀col said:
I'll do these mods to fix the tone controls on my 2nd Lepai. I'm planning to use it in the car so I'll be having the tone controls in use all the time, so it will be nice to have it sounding good. 🙂
no worries. What was the switch that you used to bypass the tone controls?
this is the minimum mods to clean up the tone control:
http://pix.minirig.org.au/main.php?g2_itemId=976
It uses 1/2W metal film 1% resistors and matched green caps (cheap better than ceremics though) and taiwan alpha pots.
If you want to do something even better, this one uses matched resistors and matched MKT caps, with the same taiwan alpha pots:
http://pix.minirig.org.au/main.php?g2_itemId=1036
col.
This is the switch I used:col said:
http://www.mcmelectronics.com/product/58-10230
Any DPDT switch should work tho. 🙂
Thanks, I'll have to order a few more bits, the only thing I have right now is resistors but they are only rated for 1/8W.col said:
I couldn't find anyone in the UK selling taiwan alpha pots, any other 100k log pot would work I imagine, are they a standard size? EG 20mm?
Panda: The toroid inductors are the better ones. 🙂
I think this may be because a battery is able to provide a bigger burst of current on start up...
I definitely want to try and reduce the turn on the Lepai I plan on using in the car. Which 10uF caps did you change for 2.2uF (I cannot see any obvious 10uF caps on my board)?
One thing I've noticed about my turn on thump, it seems to be much worse when using a battery as a power source. With my SMPS I get very little turn on thump, but from a battery I get a very loud noise and I can see the speaker cones move a lot! 😱 My battery pack is 11.1v, and my SMPS is 13v also.col said:
I think this may be because a battery is able to provide a bigger burst of current on start up...
I definitely want to try and reduce the turn on the Lepai I plan on using in the car. Which 10uF caps did you change for 2.2uF (I cannot see any obvious 10uF caps on my board)?
Panda: those Toroids are green. They are the wrong type, they should be red. There are different types/density of powder cores. If you are looking for a different board to a Lepai you could try the HiFi Audio one. Iv'e recently built an amp using one and they sound great, reasonably priced and very well implemented. Or there is Arjen's stuff which is also supposed to be very good.
There is a thread running here on the HiFi Audio boards:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=144252
Mike, maybe on your new Lepai they have used 2.2uF decoupling caps. All the Lepai's I have had have all had 10uF caps in. You can see the 2.2uF replacements I have put in here:
http://pix.minirig.org.au/main.php?g2_itemId=1069
The white ones with 2u2k written on the top 😉
Also, you should be able to find a Jaycar there in the UK as they have a branch. Thats the place to get the Taiwan Alpha B100k linear (not log) pots from.
http://jaycar.com.au/productView.asp?ID=RP7712&CATID=33&form=CAT&SUBCATID=773
ph: 0800-032-7241
col.
There is a thread running here on the HiFi Audio boards:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=144252
Mike, maybe on your new Lepai they have used 2.2uF decoupling caps. All the Lepai's I have had have all had 10uF caps in. You can see the 2.2uF replacements I have put in here:
http://pix.minirig.org.au/main.php?g2_itemId=1069
The white ones with 2u2k written on the top 😉
Also, you should be able to find a Jaycar there in the UK as they have a branch. Thats the place to get the Taiwan Alpha B100k linear (not log) pots from.
http://jaycar.com.au/productView.asp?ID=RP7712&CATID=33&form=CAT&SUBCATID=773
ph: 0800-032-7241
col.
Thanks, I assumed that because it said 2.2uf on the PCB that the caps would be 2.2uF... I guess not in the case the the Lepai! 😉 I didn't think to look on the side of the (small) caps themselves. 😱col said:
I did find something interesting tho, I used a 3 position switch for the tone control bypass mod, and when the switch is in the middle position, no signal is passed to the amp.
I tried starting up the amp (from battery) with the switch in the middle position, and no turn on thump! I did get a small thump as soon as I moved the switch into a position to pass a signal, but it was much less of a thump than it normally is.
I've ordered some 2.2uF film caps anyway now, so if my current caps do turn out to be 10uF then that problem is now solved. 🙂
Thanks again, I've not heard from that company before but it does seem like they deliver to the UK. 🙂col said:
you need to replace the input caps too. In my photo that is the big yellow ones, although 2.2uF MKTs there will do. They are also 10uF on the standard Lepai.
what happens if you phone that jaycar number? I'm curious if it's a free call to Australia or if there is some presence on the ground in the UK.
edit: so that switch you have is DPCO Double pole, centre off?
col.
what happens if you phone that jaycar number? I'm curious if it's a free call to Australia or if there is some presence on the ground in the UK.
edit: so that switch you have is DPCO Double pole, centre off?
col.
Thank you Col, Mike.
Accordingly to
http://diyparadise.com/charlize2.html
They mentioned that "No input coupling capacitor", do you think that it is reasonable?😕
Accordingly to
http://diyparadise.com/charlize2.html
They mentioned that "No input coupling capacitor", do you think that it is reasonable?😕
This thread is for Lepai. I think there is probably other threads dealing with Charlize 😉
That said, I don't like the idea of no input decoupling caps, neither do I like the idea of aircore inductors. I have too much other gear around and the less RFI flying around the better. Especially trying to listen to AM/FM radio.
col.
That said, I don't like the idea of no input decoupling caps, neither do I like the idea of aircore inductors. I have too much other gear around and the less RFI flying around the better. Especially trying to listen to AM/FM radio.
col.
Yep, the switch I have is centre off, but it doesn't need to be, it's all I had. You'd be better using one without centre off as all it does is mute the sound when the switch is in the centre.col said:
I've been really busy today, but I'll try ringing Jaycar tomorrow. I have a feeling it will go thru to Australia as I couldn't see a UK address on their site, but the UK number is a freephone number so I'm not 100% sure. 🙂
As for the Charleze, is does sound nice, nothing special tho, and you need to power it (or your source) from batteries as there are no input coupling caps... Some people have fitted toroids to the Charleze however! 😉
They've done something funny so use no input caps however, don't bypass them on the Lepai otherwise you'll get loads of DC offset I imagine.
EDIT: Definately no UK Jaycar store, I just tried doing a UK order and "All shipments are made from our Australian warehouse located in Rydalmere, Sydney" 🙂
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