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Old 29th May 2009, 06:44 AM   #291
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Quote:
Originally posted by goodgnus
I can't say. I bought my amp without a power supply, so I never had the chance to hear it with the standard 12V. I decided to go with a 13.5V because I didn't want to risk even coming close to the upper limit. Like I said, I'm really happy with it.

It is very difficult to find 13.5V, 14V 4A is much easier.

http://shop.ebay.com/items/?_nkw=14v...v+4a&_osacat=0
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Old 29th May 2009, 06:50 AM   #292
col is offline col  Australia
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I don't recommend going above 13.5v. The Lepai does not have the overshoot diodes implemented (only the undershoot). These are essential for using the amp above 13.5v. See the datasheet.

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Old 29th May 2009, 09:30 AM   #293
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Has anyone else apart from Calamaro tried bypassing the tone controls? What difference does this make, does it sound bassier than when the tone controls are set to 0?

I was wondering, does this disable the volume control also?

Finally, if I was to use a 0.1uF capacitor instead of a 2.2uF cap when bypassing the tone controls, would I then have a HPF of around 100Hz? I'm wanting to try this out in the car, up to the front speakers, and I already have a sub for everything below 100Hz and I was wondering what the easiest thing to do here is.

I'm going away for the weekend in around 8 hours, and I'd love to try out the Lapei on the road...
Quote:
Originally posted by col
I don't recommend going above 13.5v. The Lepai does not have the overshoot diodes implemented (only the undershoot). These are essential for using the amp above 13.5v. See the datasheet.

col.
Do you mean the tripath datasheet as I could not find a datasheet for this amp module?

I was wondering if it's possible to (easily) remove the 13.5v limit as according to tripath the max input voltage for the TA2020 is 16v, which would allow me to use it in the car.

My car when running has a voltage of around 14.4v.

Another option is to use diodes in series to drop the voltage, but this does waste a little power but it's not the end of the world.
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Old 29th May 2009, 09:44 AM   #294
col is offline col  Australia
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Mike, just turn the bass down, instant attenuation

If you look at the TA2020 datasheet you will see 2 lots of 4 diodes, one lot is the undershoot and the other is the overshoot. I checked on the Lepai board and the overshoot diodes are not there.

There is a 14v zener after the power supply, so this might protect the chip from overvoltage but I don't think it would sound so good.

The volume control is next up after the RCAs bypassing the tone controls won't affect it (i think).

Have a nice weekend

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Old 29th May 2009, 10:01 AM   #295
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Quote:
Originally posted by MikeHunt79







My car when running has a voltage of around 14.4v.




Mike,


In China, this amp is mainly used for cars.


Enjoy your weekend.
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Old 29th May 2009, 10:35 AM   #296
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Quote:
Originally posted by col
Mike, just turn the bass down, instant attenuation

If you look at the TA2020 datasheet you will see 2 lots of 4 diodes, one lot is the undershoot and the other is the overshoot. I checked on the Lepai board and the overshoot diodes are not there.

There is a 14v zener after the power supply, so this might protect the chip from overvoltage but I don't think it would sound so good.

The volume control is next up after the RCAs bypassing the tone controls won't affect it (i think).

Have a nice weekend

col.
Well all my stuff is packed, so now I've got the rest of the day to tinker an hope I don't melt anything!

You're right, bass all the way down = no bass (yet treble all the way down seems to be normal level )

I've just tried it in the car, works great, even with the engine running no alternator whine, I guess a zener must be cheaper than 4 diodes, I'll have another look at the datasheet when I get time.

I'm not going to bypass the tone controls, as they are acting as my crossover right now, but if I get time I'm tempted to swap out the 4558 op-amp, I've only got a TL072 handy tho, I guess this may improve things a little?

Quote:
Originally posted by panda360



Mike,


In China, this amp is mainly used for cars.


Enjoy your weekend.
Doh! I totally forgot in the e-bay listing it is sold as a car amp! I can overthink things sometimes...

I'll be sure to enjoy my weekend, we've have sun forecast for the whole weekend which is quite a rare thing in England.
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Old 29th May 2009, 11:49 AM   #297
col is offline col  Australia
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Quote:
I've only got a TL072 handy tho, I guess this may improve things a little?
Wouldn't bother with the TL072 it's about the same quality level as a JRC4558. Iv'e tried mine with NE5532 and LM4562 both of them sound great, the NE5532 is much cheaper though.

It's a really good feature to have a opamp pre with tone controls. It's much more versatile than just a volume pot, means you can use it with a wider range of inputs and different speakers. If you bypass the tone controls then you need speakers with a flat response ($$$). Would be really good to have a tone bypass switch so you had the option of off or on though. I notice that Lepai have done that with one of their other amps.

http://cgi.ebay.com.au/NEW-MINI-LEPA...rkparms=66%3A2|65%3A1|39%3A1|240%3A1318|301%3A0|293%3A1|294%3A50


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Old 29th May 2009, 01:32 PM   #298
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Quote:
Originally posted by col


Wouldn't bother with the TL072 it's about the same quality level as a JRC4558. Iv'e tried mine with NE5532 and LM4562 both of them sound great, the NE5532 is much cheaper though.
Cheers, I'll leave the JRC4558 in for now then until I pick up something a little nicer.

Quote:
Originally posted by col

It's a really good feature to have a opamp pre with tone controls. It's much more versatile than just a volume pot, means you can use it with a wider range of inputs and different speakers. If you bypass the tone controls then you need speakers with a flat response ($$$). Would be really good to have a tone bypass switch so you had the option of off or on though. I notice that Lepai have done that with one of their other amps.

http://cgi.ebay.com.au/NEW-MINI-LEPA...rkparms=66%3A2|65%3A1|39%3A1|240%3A1318|301%3A0|293%3A1|294%3A50


col.
Bose chips!

That is a good idea, I don't think it would be that hard to put a switchable tone bypass on this Ta2020 amp tho, if you just used a dual gang switch and put it inline with the bypass cap and resistor, then you should have a switchable tone control bypass shouldn't you?

Have you ever had this amp cut-out at all? I was trying it out in the car, and it's roasting hot in the car cabin. The whole amp case was warm, so I think it's gone into thermal protection.

It's now cooling off and I'll try it again in a bit... I hope I've not damaged it...
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Old 29th May 2009, 02:06 PM   #299
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Quote:
Originally posted by col


The volume control is next up after the RCAs bypassing the tone controls won't affect it (i think).

Yes:
RCA ->volume pot ->input capacitors ->input resistors->TA2020
(as in TA2020 datasheet)
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Old 29th May 2009, 07:24 PM   #300
aszu is offline aszu  United Kingdom
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Thanks Calamaro for amazing mods and easy to follow photos!

1. I swapped cap in the PSU to a high quality Jamicon 4700uF 35V. Its physical size is just enough, so I didn't have to remove diode/inductor.

Immediately after the change, bass became fuller, richer, better controlled.

Could you please tell me why you connected 100nF film cap alongside with the big cap? As far as I know this additional cap shouldn't make any difference..

2. I bypassed tone controls according to your suggestion. Wow! What a difference! I can't believe this amp is sounding ever better! Sound is now like a crystal - very clean, almost analytic. However, for me it is lacking bass a little (previously my bass knob was set at 2 o'clock).. but there is no problem if you use eq

I couldn't find such a big (2.2uF) film caps in my area, so I got 2.2uF 100V Jamicon electrolytic caps. Also, used audiophile-grade OFC wire for routing the signal.

3. Has anyone tried replacing bulk capacitors? Is is worth?


Some photos:
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