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Old 16th May 2010, 08:33 PM   #571
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Quote:
Originally Posted by engelhornc View Post
I bought a pair of these a few weeks ago. One is for a friend who needs a small amp in his diesel rock-hauling truck so he can hear his Garmin. The other is for the back patio of a small restaurant here in town. Mine came with some "2A" power supplies - but I'm guessing they'll never deliver 2 amps unless they dead short to the mains... but I digress.

Out of the box these little amps sound pretty good, and they're not "terribly" built. Not too terribly, anyway. I read this thread a few times so I was prepared to fix a few things.

For my friend in the truck - well, he can plain live with the unit as delivered.

For the restaurant... well I thought I'd implement a few of the fixes and see how things work out before I get my own unit.

1> replaced the opamp with ne5532.
2> fixed the tone control component values, thanks DrLex.
3> replaced the input caps
4> fixed the wacked DC offset to the speakers, 60mV and 140mV..
5> found a 4.5A 12V switching supply and set it to 13.3V output voltage.
6> ordered some 10uH toroids... but this is the last fix I'll do on this unit.

I used ZZ Top's "Tres Hombres" and "Fandango" as my test music. There are some great transients (La Grange), good bass lines, and mostly I'm familiar.
The frequency responce irritated me right off the bat, as did the fact that the puny power supply was obviously farting out whenever I pushed the amp at all. The bass and treble controls just seemed like weird filters... yes they adjusted the bass and treble regions, but I couldn't get anything near a flat response to my ear.

After the fixes (and I'm still anticipating a bass improvement with the new toroids) I have to say that this is a really fun little amp. The tone section is usable, the power level is impressive, and most importantly I really enjoy listening. Oh - my test speakers are just ok - a pair of Madisound "Recession Busters" from last year.

I'm going to buy another one and mod it for myself. I have a set of Klipsch La Scalas down in my garage and I'm eager to put a little Ipod, this little Lepai, and those big ol' speakers together. No one will believe it.

Thanks for the great info!

Craig
this is the closest post to an all in one tutorial (minus the zener). If someone could maybe post exact parts such as the component valves and caps then it would be better. Pics would help also.
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Old 16th May 2010, 09:59 PM   #572
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Ok so here is my little list that I put together so far.

1. Remove the zener.
- Not sure what it does but everyone says to remove it bc it can blow the amp.
2. Replace the opamp with a ne5532.
- Don't know what that does... something with tone control?
3. Replace input caps with 2.2uf metallized polypropylene (google says its 2 L's but firefox says it's 1 L, idk how to spell it.)
- Again, I don't know what this does
4. Replace inductors with 10uH 3A toroids.
5. Fix tone control component values.
Click the image to open in full size.
Code:
R1 (installed 10k, marked 15k): 20k
R3 (installed 1k5, marked 1k): 2k2
R4 (installed 1k, marked 1k5): 10k
C1 (installed 10n, marked 472): 5.6n
C2 (installed 47n, marked 393): 56n
C3 (installed and marked 10n/103 near bass pot): 1n
C4 (installed and marked 10n/103 near treble pot): 10n
that's all I really have for now. I will do some more searching through this thread. If anyone wants to reply to this and throw in some info, they can and I will edit this post.

Last edited by j0ckinjz; 16th May 2010 at 10:15 PM.
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Old 17th May 2010, 02:34 AM   #573
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Quote:
Originally Posted by Fabio555 View Post
Hi all, i've a question...
i tried to tweak my lepai T-amp...for now i only changed the operational with a Ne5532P... now the amp sounds very smooth... too smoth...is impossible, the gain is too low!!! Why this problem? i tried to put back the old op-amp and the sound was good and loud again... If we change the op-amp or we bypass can we use the lepai with a low signal source like ipod nano?? or we need a preamplifier??. thanks

Base on information from this forum, I have tried both methods.
1. changed the operational with a Ne5532P
It depends which op-amp is using, you may try other one. It is interesting experience to change different op-amp, you will have different sound style. Of course, some op-amp is more expensive than the Lepai amp.
2. Bypass op-amp
Just simply change the input resistor value.
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Old 17th May 2010, 09:21 AM   #574
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Location: Wiltshire, England
Default Mods...

Although posted previously, I have re-edited and posted my modifications again to bring them together with other TA-2020 user mods in this thread...

A) changed 3.3uF input Caps to 2.2uF MKT types
B) swapped 2200uF for 4700uF Panasonic FC
C) changed all other 3.3uF electrolytics for 2.2uF Panasonic FCs
D) changed 330uF for 470uF Panasonic FC
E) swapped op-amp for NE5532P
F) added d.c. trimmers etc. (as per #465 on Pg 47)
G) changed tone circuit capacitors (with 1nF, 10nF, 5.6nF and 56nF / 5% bought off eBay) and resistors (20k, 2k2, 10k metal film 0.4W/0.1%) as per post #484, Pg49. Also replaced 430R (marked 100R *2) with wire links.
H) changed pots: volume (50k Dual Log RS 249-9288), bass & treble (100k Dual Log Rapid Electronics 65-1466).
J) changed inductors for 10uH/2.8A (RS 233-5134).

Some issues I encountered...

1. original control knobs did finally come off with (not so) gentle prising but one tone control spindle broke from the slider inside the pot.

2. The new cermet tone control pots had a larger screw thread so had to enlarge the holes on the faceplate. They also sit slightly forward of original ones which means front faceplate now has slight bow in it (about 1-2mm).

3. Had to drill small hole in plastic see-through bezel (around volume control) to take the small metal positioning lug on the new pot. However, because tone pots were slightly forward, was unable to fully tighten fixing screw on volume pot so the positioning lug does not need to mate with new hole!

4. The original plastic control knobs have longitudinal flutting to secure them to the old pots (which are also flutted). However the new pots had plain spindles. Therefore decided to replace control knobs with some aluminium ones I already had in my spares box.
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Old 23rd May 2010, 12:23 AM   #575
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Default Lepai TA2020 and... these?

Do you think the Lepai TA2020 is powerful enough to run a pair of Tannoy Reveal 601p speakers? Specs!

8 Ohms -- Nominal Impedance
89dB -- Sensitivity SPL/ 1W @ 1m
<0.6% -- Distortion

My current speakers are Alesis Monitor Ones: 88db sensitivity at 4 Ohms. They sound great, but they're 15 years old and scuffed up enough that I'd like to replace them.
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Old 31st May 2010, 06:39 PM   #576
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Hi. New to this forum.

Just got a Lepai TA2020 from ebay and really impressed with the sound. Almost think it's better than my Sonic T-amp. Unfortunately after a few days the left channel has gone quiet. Is there anything I should check before I try and return it? Not much of an electronics type person but can follow instructions and am reasonable with an iron.
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Old 30th June 2010, 12:47 AM   #577
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Hey guys, I've been looking at this thread for quite a while and decided to buy a Lepai TA2020. It came today and from what I've read, it's better that I remove the zener diode before using it. When I turned it on, there was a pop noise(which I believe is the typical pop sound when it's turned on). I turned it off to plug my speakers and input cable, and after I turned it on, there wasn't any pop noise. I played my music through my MP3 player and no sound came out. I tried it with my laptop, still no sound. Is this due to the removing of the zener diode? I'm using a monitor's power supply that's 12v(12.16v with a multimeter) 5A.
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Old 10th July 2010, 10:50 PM   #578
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Hi everybody!

I bought a lepai lp-2020 some weeks ago. I've played music with it regulary at home until some days ago. Yesterday I build a boombox which it should be installed in. But when I built in all stuffs in it (amplifier, battery, speakers) and decide to use it nothing happened. I've tried it with both the battery and the following net-adaptor but it seems stonedead. The blue led doesn't light and no sound at all from the amplifier. I've opened the amp and can't find any parts that seemes to be burned. Anyone got some ideas or thoughts what may be wrong?

Regards Lennan
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Old 11th July 2010, 08:07 AM   #579
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Default Toroidal inductors

Very cheap, they fit perfectly. Huge sound improvement.

http://cgi.ebay.it/Choke-coil-for-cl...item3eff1d6665
Attached Images
File Type: jpg lepai.jpg (401.7 KB, 751 views)

Last edited by Calamaro; 11th July 2010 at 08:12 AM.
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Old 13th July 2010, 10:40 AM   #580
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Now i have bin reading this for like 2h. My first Lepia broke after a few days and annother is on the way.
My knowledge on all the names and nummers that u guys type is Zero! So i need, as a few of the members requests, is a turtorial. Not just name on stuff u need. We need detaild picture "where" to put "what" on the Lepia. IT whould really help me and some of the others novis here wrry much.

* My first consern is how to NOT make it break after 2 days
* Then how to, easyle, switch some parts to make it work better.
* Make the instruktions simple, so 5 year old can make it.
* Retard as i am, i need pictures, pictures with arrows where to put the part and so on.

I live in Sweden so i rather not have som links to ebay, have no time to wait and to pay for shippment.


I really hope for an awnser on this post, and i hope my limping english works =)
// Gunnar
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