Budget T-Amp Shootout - Lepai vs. Indeed TA2020

[XtremeRevolution]

Re: Budget T-Amp Shootout - Lepai vs. Indeed TA2020

Ahhh...so what we really need is somebody to measure a modded Lepai and the Indeed.



True...true. Also remember, the Indeed does not come with a power supply, so taking that into consideration, it's a lot more expensive than the stock Lepai.


Now that you've mentioned it, I didn't think about the fact that I used a 5A PS on the Lepai which normally comes with a 2A PS.

I should redo this listening test with the supplied 2A PS for the Lepai. Perhaps that perceived extra power and muddy, crappy bass when the volume is cranked on the LEPAI is because of the bigger PS ??

The bigger PS allows you to get more output out of the Lepai amp before it shuts down on its own due to undervoltage or starts clipping. Try a bass heavy track and play that on the Lepai amp for a while. You'll notice the lights start dimming as you crank it louder, then it just shuts off. Doesn't do that with the 5A power supply.

The calculations are simple. The amp is rated for 20W RMS x 2, so 40W RMS. In order to deliver 40W RMS, you need to pull 3.33 amps at 12V. A 2A power supply simply cannot keep up.

No, IMO it's worse with the 2a.

I bought the Lepai last week and purchased the ebay PS and upgrade parts as well. The PS arrived on Monday after I had been listening to the amp for a couple days. The 5A is a significant upgrade.

What he said.

Good stuff. Thanks. You saved me some time.

Just for yucks I'm going to try to squeeze in some FR measurements with TrueRTA tomorrow, but no promises with Christmas right around the corner.

Not sure if this will even yield anything worthwhile, but I'll give it a go. I will set levels around 2v at the speaker terminals with pink noise, and then do a nearfield spectrum sweep measurement for each amp and see what the graphs say.

Looking forward to it. What you really need to do now is compare the modded Lepai to the stock Indeed. Seems like the price difference is pretty small (not including the time needed to modify the Lepai amp), but I'm certain that you'll notice a difference if you haven't yet modded one.

Whereabouts in Chicago are you again? I could let you borrow a Modded Lepai amp to test if you'd like. I have two right now and I don't need to use both of them all of the time.

[bkeane1259]

Re: Budget T-Amp Shootout - Lepai vs. Indeed TA2020

Whereabouts in Chicago are you again? I could let you borrow a Modded Lepai amp to test if you'd like. I have two right now and I don't need to use both of them all of the time.

That sounds like a plan for the New Year.
I'm by Soldier Field, in the South Loop.

[Whitneyville1]

Re: Budget T-Amp Shootout - Lepai vs. Indeed TA2020

Xtream, is it "doable" to put a sub-sonic filter on the input side of the Lepai? At it's limited power, I'm thinking anything below 18Hz is a waste. Maybe the factory has done this for us already. I wish there was something available price/power-wise between the 12-25 WPC amps and the DTA-100a, besides thrift-store 35 watt receivers of questionable repute. My Dad has a nice Realistic 45 WPC receiver with a bad power transformer and I can't find a whiff of a schematic for it. It's probably a 25.2 volt center tapped, but one of his "friends" shorted the speaker terminals for a LONG time and now the main fuse pops when the power hits it. I gave it to him for his Birthday/Father's Day present for his studio/darkroom, and he wouldn't mind me using it if I could.

[XtremeRevolution]

Re: Budget T-Amp Shootout - Lepai vs. Indeed TA2020

That sounds like a plan for the New Year.
I'm by Soldier Field, in the South Loop.

Ah, you're literally near downtown. I'm in New Lenox and work in Downer's Grove.

In that case, I can ship you one if you'd like to review it if you don't mind spending the $5 or so to flat rate ship it back to me.

Xtream, is it "doable" to put a sub-sonic filter on the input side of the Lepai? At it's limited power, I'm thinking anything below 18Hz is a waste. Maybe the factory has done this for us already. I wish there was something available price/power-wise between the 12-25 WPC amps and the DTA-100a, besides thrift-store 35 watt receivers of questionable repute. My Dad has a nice Realistic 45 WPC receiver with a bad power transformer and I can't find a whiff of a schematic for it. It's probably a 25.2 volt center tapped, but one of his "friends" shorted the speaker terminals for a LONG time and now the main fuse pops when the power hits it. I gave it to him for his Birthday/Father's Day present for his studio/darkroom, and he wouldn't mind me using it if I could.

You should be able to run a subsonic filter on the input side. I'm not sure how one would wire it up though, but perhaps someone can look into it? I wish I knew more about this kind of thing.

I'd question the need for it though. What material digs that deep that you'd listen to?

[bkeane1259]

Re: Budget T-Amp Shootout - Lepai vs. Indeed TA2020

I can ship you one if you'd like to review it if you don't mind spending the $5 or so to flat rate ship it back to me.

Sure...sounds like a plan. Check your PM.

[Mikers]

Re: Budget T-Amp Shootout - Lepai vs. Indeed TA2020

Interesting, Indeed also sells the Lepai on ebay

http://www.ebay.ca/itm/2011-New-Vers...-/290534649380

[Whitneyville1]

Re: Budget T-Amp Shootout - Lepai vs. Indeed TA2020

I still believe in vinyl and I'd just as soon keep anything below 20Hz out of a Lepai (kitchen music). My AVR has four sets of "pre-outs" ("Zones")....if I could teach it to do the dishes...:D

[bkeane1259]

Re: Budget T-Amp Shootout - Lepai vs. Indeed TA2020

These should work, but I'm not sure if you'd want to spend the $$$ on it for a $20 amp.

http://store.hlabs.com/pk4/store.pl?view_product=13

[JimHRB]

Re: Budget T-Amp Shootout - Lepai vs. Indeed TA2020

Interesting, Indeed also sells the Lepai on ebay

http://www.ebay.ca/itm/2011-New-Vers...-/290534649380

And a price of $30 without the PS. PE has it for $19 today as the BOTD.

[lhwidget]

Re: Budget T-Amp Shootout - Lepai vs. Indeed TA2020

Bryan,
Two things:
About an input filter; I would expect both amps to be AC coupled (i.e., they have a simple 6 dB/octave filter on each input channel to roll the amps' response off somewhere in the sub-sonic region and prevent DC signals from entering the amps' gain stages).

This doesn't mean you can't add another at a higher cutoff frequency. The components labeled Cin and Rin in the attached schematic are the input filter for a single channel chip-amp. Values of 3.6k Ω and 2.2 µF will yield an F3 of 20.1 Hz. The cap goes in series in the + signal lead, and the resistor goes between the hot and ground of the signal lead. You can add this outside the amps (just like the F-Mods) or get creative and connect the filter's output to the signal chain after the the input filters in the amps (remember to pull the resistors in the filters on amp's circuit board though, otherwise the original resistor will be in parallel with your added resistor and change the tuning of the filter).

Here are some parts you could try if you want to experiment with a 20 Hz high-pass filter on the amps' inputs:

http://www.parts-express.com/pe/pshowdetl.cfm?Partnumber=002-3.6K

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=027-415

The cap will be too large to put inside the amps, but they're cheap and you could probably use them in XOs later.

About testing the amps. Check out RightMark's audio test suite. If you include the amp in the loop-back chain you'll be able to see how it and your sound card perform. Do a loop-back test on your sound card for a baseline, then include the amps in the chain. It's a very thorough test suite for sound cards, amps, and CD players. Look here if you're interested:

http://audio.rightmark.org/index_new.shtml

[ernperkins]

Re: Budget T-Amp Shootout - Lepai vs. Indeed TA2020

With the limited power of these amps, I'm not sure the tone controls on the Lepai are a benefit, especially with the remarks made about the tone controls on the Lepai. Do we have an MSRP with S&H of the Indeed as a comparision to the Lepai w/PS cap mods? I have an old ATX 'puter supply (like 9 amp @12 volts) to push either one that's collecting dust. A modest (+1.8 volt?) over the rated "12 volt" input would be helpful to those who might plan to use them in a car/truck/boat (nominal 13.8 volts of a charged lead-acid battery).

I tried my Lepai with a 13.8 VDC, 3 Amp Radio Shack power supply and it didn't work. IIRC the Lepai has an overly protective overvoltage protection circuit that ties to the chip's fault line. With 13.8 VDC the unit will light up, but not work. I ended up getting a 12 VDC, 5 Amp PS. YMMV.

Regards,
Ed

[bkeane1259]

Re: Budget T-Amp Shootout - Lepai vs. Indeed TA2020

Thanks for the info. I am just barely aware of RMAA. I've never used it before, but I'd be willing to give it a whirl. Once I get the modded Lepai from XR, I will have 3 amps to test. Maybe we'll get some interesting data.

Correct me if I'm wrong, but I will need a dividing network between the amp's speaker outputs and the line-in on my sound card, right? I'm not going to be able to do measurements of the amplifier at a decent (high) volume level without something to limit the voltage going into my sound card.

I also don't want to destroy my Asus Xonar STX.

Can you briefly explain the setup for measuring an amplifier with RMAA? I have all sorts of values of resistors on hand and I have a good 8-ohm dummy load that can handle a crapload of power. In the meantime, I will try to do some research myself.....just don't want to blow anything up. The wife doesn't think it's cute when my projects involve fire, smoke, etc.

[lhwidget]

Re: Budget T-Amp Shootout - Lepai vs. Indeed TA2020

Hey Bryan,
I used the same divider network I use with SoundEasy for impedemce curve captures; A pair of 1/2W resistors, 22kΩ from + speaker lead to ground, and 47 kΩ in series in the + speaker lead, then on to the sound card input channel.

RMAA is really easy. Run a loop-back test on your sound card first. Just plug the sound card's line outs into its line inputs, set the test levels, then run the test. RMAA will do the test automatically, and generate all the test graphs.

For the amp test, plug the sound card's line outs into the amp, and the voltage divider outputs into the sound card's line inputs.

Since RMAA uses a stereo loop-back test, there is no provision for a reference signal (other than the original internally generated test signals) to seperate the sound card's characteristics from the amp's, its response and distortion will be included on top of the amp's determined specs since they're in series.

Any 10W 4Ω or 8Ω resistor should be fine for a load. Also, I'd test them with speakers for loads. I think it was Pete Schumacher who noticed some very strange freq response characteristics from some sort of class D amp when it was presented with reactive loads.

[smokarz]

Re: Budget T-Amp Shootout - Lepai vs. Indeed TA2020

i ordered the lepai, but cancelled so i am going to buy the indeed.

what power supply would work with the indeed?

i have something that says 15v 1000ma. would that work?

thanks

[bkeane1259]

Re: Budget T-Amp Shootout - Lepai vs. Indeed TA2020

i ordered the lepai, but cancelled so i am going to buy the indeed.

what power supply would work with the indeed?

i have something that says 15v 1000ma. would that work?

thanks

NO !!!

DO NOT use a 15V PS on the Indeed or the Lepai. You could do irreversible damage.

This is ideally what you want -- A 12V 5A PS

Stick with 12V and up to 5A and you will be good.