Hi there I am being weird and modifying a much more obscure amplifier that actually cost me a grand total of £7! It was the cheapest amplifier I could find at the time straight from china on ebay and uses the TDA7057Q pdf, TDA7057Q description, TDA7057Q datasheets, TDA7057Q view ::: ALLDATASHEET :::! Thing is I actually really love the sound from this little amplifier I used it for many years. After buying "upgrades" and usually being disappointed I decided maybe I should just modify this little badass for more clarity.
I took some photos of it's internals:
Prime Photos
I don't really know anything about this stuff but I did modify the Lepai 2020 and it sounded great! Only time I retired my LP-A2.
I assume I need to get a higher rated cap for the power input, maybe 10000uf?
If it can fit in the box.
And replace the other capacitors with similar values but high quality film caps?
I assume making these changes will improve the sound. I guess I could look into disconnecting the EQ from the circuit to?
Either that or I buy a couple TDA7057Q's and just build something from scratch, whatever I do I will do it as cheaply as possible.
Any advice will be much appreciated!
Would buying a better transformer and making an external power supply help?
Dom.
I took some photos of it's internals:
Prime Photos
I don't really know anything about this stuff but I did modify the Lepai 2020 and it sounded great! Only time I retired my LP-A2.
I assume I need to get a higher rated cap for the power input, maybe 10000uf?
If it can fit in the box.
And replace the other capacitors with similar values but high quality film caps?
I assume making these changes will improve the sound. I guess I could look into disconnecting the EQ from the circuit to?
Either that or I buy a couple TDA7057Q's and just build something from scratch, whatever I do I will do it as cheaply as possible.
Any advice will be much appreciated!
Would buying a better transformer and making an external power supply help?Dom.
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This is a particular situation corresponding to "pimping" a Trabant/"Trabi" (a Trabant is a very simple 2-stroke car build in something like Pertinax, phenol-treated and compressed paper, and has a lot of charm. From the East German days).
From a rational point of view: rip out the old circuit and build a new based on a higher performing IC. But, just like with the Trabant, it will not be the same.
If you really insist on being irrational and nostalgic, better capacitors, metal film resistors and a supply with good margins will improve the sound a little. Worth the effort? - you decide.
From a rational point of view: rip out the old circuit and build a new based on a higher performing IC. But, just like with the Trabant, it will not be the same.
If you really insist on being irrational and nostalgic, better capacitors, metal film resistors and a supply with good margins will improve the sound a little. Worth the effort? - you decide.
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For the time being TA2024 boards from China are very inexpensive. EUR 4,- for an assembled board. As you are one of those (I support) not demanding much power.
For the Lepai, it is difficult for others to understand how much you are attached to that sound. As long as it gives you pleasure, go on. Being a "cool" outsider, it is not rational behavior that will be the driving force.
For the Lepai, it is difficult for others to understand how much you are attached to that sound. As long as it gives you pleasure, go on. Being a "cool" outsider, it is not rational behavior that will be the driving force.
Yeah ok thanks. If I buy an assembled board then make a decent power supply and put good caps into it that will no doubt be a good sound?
Yeah I have played this amplifier speaker combo to people they are always impressed by how much bass comes out of this system. The high end sits just right and mids are there and clear but not in your face. Subtle.
Ah well as long as I am getting good mixes out of it. I might consider two amplifiers with a switch depending on what I am listening for; great thing about having passive speakers
So basically you are saying that trying to modify the Lepai LP-A2 is like trying to polish a turd?
Yeah I have played this amplifier speaker combo to people they are always impressed by how much bass comes out of this system. The high end sits just right and mids are there and clear but not in your face. Subtle.
Ah well as long as I am getting good mixes out of it. I might consider two amplifiers with a switch depending on what I am listening for; great thing about having passive speakers
So basically you are saying that trying to modify the Lepai LP-A2 is like trying to polish a turd?
No, I am not that rigid. I have seen many pimped Trabants and their owner are more happy and proud than those with a Mercedes.
I know the (sweet) feeling of having something that means something to you though you perhaps already have or can afford better. This if why I keep my late fathers Beomaster 1000. It belongs to me in a different sense.
As engineers we are taught to be rational - will it pay off? In your case, most engineers will conclude it is not worth the effort. But, I can hear from you it is a subjective appreciation that gives you more pleasure than another, theoretically better performing amplifier.
Give it a chance.
A more stable decoupling of the supply rail can only improve matters.
10000uf is fine.
For the capacitor between the input connector and the IC, use foil capacitors if not already foil.
I see an 8 pin IC, what is that?
Clean the potentiometers with contact spray (the type also for potentiometers).
Be careful with the Pertinax type PCB. It is less resistant to heat than a fiber-glass board. The copper tracks may loosen.
I know the (sweet) feeling of having something that means something to you though you perhaps already have or can afford better. This if why I keep my late fathers Beomaster 1000. It belongs to me in a different sense.
As engineers we are taught to be rational - will it pay off? In your case, most engineers will conclude it is not worth the effort. But, I can hear from you it is a subjective appreciation that gives you more pleasure than another, theoretically better performing amplifier.
Give it a chance.
A more stable decoupling of the supply rail can only improve matters.
10000uf is fine.
For the capacitor between the input connector and the IC, use foil capacitors if not already foil.
I see an 8 pin IC, what is that?
Clean the potentiometers with contact spray (the type also for potentiometers).
Be careful with the Pertinax type PCB. It is less resistant to heat than a fiber-glass board. The copper tracks may loosen.
I started to mess around with ClassD amps when I first joined Diyaudio. This was in the days of the Sonic Impact modding frenzy and the other Tripath TA2024 based amps. These were in reality no more than 5w per channel (said to be 15w per ch, but only at 10% distortion)
IMO things have moved on greatly in the last 10 years. I see your amp is said to be 3w per channel which is ok if you have efficient speakers or you are not trying to thrash it.
I recently built a couple of IRS2092 amps, one with a board from Sure Electronics and the other were mono boards from Ebay. Both versions give good sound. I had to buy a new transformer to power the Sure board, the other bits I already had, so for about £100 I have a really nice amp. The Mono boards did not require any other purchases as I had a suitable transformer, the boards were about £10 each. The Sure (39$)board should give me about 200w into 8 Ohms and the mono boards about 70w. If you are looking to go up in SQ then I would be looking to build something like these. I have have had most of the ClassD boards that have appeared on here over the years and IMO the latest stuff sounds the best.
IMO things have moved on greatly in the last 10 years. I see your amp is said to be 3w per channel which is ok if you have efficient speakers or you are not trying to thrash it.
I recently built a couple of IRS2092 amps, one with a board from Sure Electronics and the other were mono boards from Ebay. Both versions give good sound. I had to buy a new transformer to power the Sure board, the other bits I already had, so for about £100 I have a really nice amp. The Mono boards did not require any other purchases as I had a suitable transformer, the boards were about £10 each. The Sure (39$)board should give me about 200w into 8 Ohms and the mono boards about 70w. If you are looking to go up in SQ then I would be looking to build something like these. I have have had most of the ClassD boards that have appeared on here over the years and IMO the latest stuff sounds the best.
thanks so much for your input and advice interesting indeed! A worthwhile investment.
I will open it again and take a look!
Maybe I should even buy better potentiometers ?
I will clean!
Also I noticed that the two amp chips on the bottom are really rusty!
Will that effect the sound? Maybe that is why it sounds so good hahah.
Adding to what's already been said - sure, go ahead and mod your Lepai TDA7057. Be a pioneer!
I recommend against modding the Lepai TA2020. I recall that the better sounding TA2020 amp boards often had custom-wound output inductors, and this is the area where you would be likely to achieve the most benefit. But it's likely to be difficult to find a suitable equivalent.
Also maybe consider a power supply upgrade. Linear power supplies for ham radio are considered good for class D amps (and chip amps) and a well known one on this forum is the Astron RS-12A. You may be able to pick up one cheap on eBay.
I recommend against modding the Lepai TA2020. I recall that the better sounding TA2020 amp boards often had custom-wound output inductors, and this is the area where you would be likely to achieve the most benefit. But it's likely to be difficult to find a suitable equivalent.
Also maybe consider a power supply upgrade. Linear power supplies for ham radio are considered good for class D amps (and chip amps) and a well known one on this forum is the Astron RS-12A. You may be able to pick up one cheap on eBay.
I will open it again and take a look!
Maybe I should even buy better potentiometers ?
I will clean!
Also I noticed that the two amp chips on the bottom are really rusty!
Will that effect the sound? Maybe that is why it sounds so good hahah.
The two chips on the rear side must be the TDA7057. It should not be rust as there should be no iron. It may be old soldering cleaning agent (grease). Have you got some isopropyl alcohol (used in households for removing grease-stains)? Take a rather stiff painting brush, dip it in the isopropyl alcohol and rub areas with dirt several times. Let it dry well afterwards. It may end up looking like new.
The rust could be why Dean Martin sounds so good.
Correct potentiometer cleaning can make them as good as new. For a start, don't replace.
The 8 pin IC, what is written on that?
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