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  • #31
    Re: New Lepai amps?

    Umm, LOTS of home audio amps sold in the 70's with NPN and PNP output transistors only used 12 volts AT 140 AMPS to provide 35 watts per channel. I still have the one I bought in the PX in So VN in 1972, a Sankyo (not Sanyo) brand. It still weighs 69 lbs, 80% is the power supply and draws 1380 watts @125 volts. The amplifier in my Dakota draws 85 amps @14.1 volts at full output. It's just 270 watts RMS total. Watts in volts input can NEVER exceed wattage output in audio or radio power. That's called "DeForrest's Law". Lee DeForrest the inventor of the "audion" tube,the first amplifying tube (the triode). If you figure out a way to do it, let me know. I'll get make you the richest person in the world overnight as the inventor of "Entropic Energy". (Power from nothing.)











    w

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    • #32
      Re: New Lepai amps?

      Originally posted by Whitneyville1 View Post
      Umm, LOTS of home audio amps sold in the 70's with NPN and PNP output transistors only used 12 volts AT 140 AMPS ... The amplifier in my Dakota draws 85 amps @14.1 volts at full output. It's just 270 watts RMS total. ...
      Remember there are both step-up and step-down transformers...

      You can certainly get 270W/ch capability out of a 14.1V, 85A source, you're just applying much more than 14.1V to your speakers to dissipate that kind of power, nearly 33V @ 4 ohms. These little Lepai amps behave like their voltage at the speaker is limited to their input voltage.

      I hadn't heard of De Forest's Law before...

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      • #33
        Re: New Lepai amps?

        Well, looks like there's a few more Q&As on the PE site for these amps. My interest in the 2.1 has been lowered a bit since it seems the built-in xover is a 6dB/oct slope. I really wish they had melded the 2.1 and 4ch amps into one (or offer the same playback features on the 2.1 model)...but I guess that's their way to get us to buy 2 amps instead of 1.

        I wonder what other brands will come out in the next few months that will mimic the Lepais. I'm hoping one of those brands will have the mp3/usb/sd/fm support in a 2.1 amp with a LPF of at least 12dB/oct.
        Nichikuros - Peerless 831735 Nomex + Vifa NE25VTA
        Digger8 - Small compact 8" sub with F3 = 20Hz
        Madison-D and Madison-R - Tang Band W4-1720 + Vifa BC25SC06 or Beston RT003C (TM and MTM)
        Jeffrey - Tang Band W5-704D + Beston RT003C
        Jasmine - Fountek FW146 + Fountek NeoCD3.0 Ribbon in Pioneer BS21 Cabinet

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        • #34
          Re: New Lepai amps?

          All of these amps actually output between 3 and 5 unclipped watts per channel. Garbage.

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          • #35
            Re: New Lepai amps?

            Originally posted by awwnuts View Post
            All of these amps actually output between 3 and 5 unclipped watts per channel. Garbage.
            And how many 2020 and 2024 amps do you have? They should put out ~6w/ch at 0.1%thd. Garbage? I guess all of those 2A3 and EL34 SET's are garbage too.

            Bob

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            • #36
              Re: New Lepai amps?

              Originally posted by Bob Brines View Post
              And how many 2020 and 2024 amps do you have? They should put out ~6w/ch at 0.1%thd. Garbage? I guess all of those 2A3 and EL34 SET's are garbage too.

              Bob
              Strawman,

              I have at least two dozen amps like this in various forms (mostly raw boards).

              If you're expecting low power - great. My point was that it falls well short of its claimed output. A recent test of this LP-168HA shows that there are more problems than just power output.

              http://www.youtube.com/watch?v=NIOpo...el_video_title

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              • #37
                Re: New Lepai amps?

                The Lepai 2.1 does test pretty poorly. I didn't expect it to meet the power claims. In fact, they make about the expected power. Whats disappointing are the poor performing LPF and sensitive sub control. I completely lost interest in the 2.1.

                Looks like PE has some more Lepai amps now. The new 4ch looks to be three same as the one introduced a few weeks ago. While PE lists lower power for the new one, chinese sites still show the 4x45w rating.
                I found a chinese site that had pics of the new 4ch internals. I could barely make out the PN of the amp chip, but after researching, they look to be ST Micro TDA7297 bridged 2ch class AB chips. I'm sure the other amps use the same chip for stereo outputs. This chip makes about 5-7w at 1% distortion with 12v supply.
                While I'm disappointed these are class AB, I di like the feature set, so the 4ch offerings still interest me, though I'd only use 2 channels.
                Nichikuros - Peerless 831735 Nomex + Vifa NE25VTA
                Digger8 - Small compact 8" sub with F3 = 20Hz
                Madison-D and Madison-R - Tang Band W4-1720 + Vifa BC25SC06 or Beston RT003C (TM and MTM)
                Jeffrey - Tang Band W5-704D + Beston RT003C
                Jasmine - Fountek FW146 + Fountek NeoCD3.0 Ribbon in Pioneer BS21 Cabinet

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                • #38
                  Re: New Lepai amps?

                  FWIW, here's some highly unscientific, non-objective feedback on the new Lepai's in question from an actual owner/user. I have the 4ch MP3 amp and it's powering 2 nd91s in a boombox for garage use (see the Projects section of the forum). For its intended use of moderate quality, non-critical listening, the amp does just fine with the included power supply. The drivers are pushed to their limit without any audible clipping that I can hear as the cones are dancing past their stated ~4mm Xmax (but under the suspected Xmech that is much greater), all the while the heatsink/case is barely warm to the touch. I'm quite happy with my purchase. Sure, those with more technical skill could probably cobble together a DIY unit with the same features and power output, but in the final analysis, would the cost saving of a few bucks really be worth the time?

                  We can haggle about the unethical practices of vendors listing power ratings that are perhaps overstated, but if we were to eliminate overstated claims from all the vendors on PE as well as every other retailer, 40% of the internet would suddenly be gone (with the remaining 60% of course being pron). In PE's defense, in the Q&A section of the 4ch amp I bought, a staffer provides at least a reasonable estimation of measured power with the included power supply. Let's give props to PE for at least trying to attenuate manufacturers wild claims.

                  The reality is that for many of the intended uses of these amps, most users really only need a few clean watts to get the output they need (e.g. my boombox). Arguing that these cheap lil' amps don't really get to the manufacturer's claim is like saying that women should sue Victoria's Secret because they don't look like supermodels when they wear VS's products.

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                  • #39
                    Re: New Lepai amps?

                    I think for the ~$40.00 cost, you'd be hard pressed to build any kind of DIY amp with a power supply. Of course, with the exception of those who already have the parts on hand.
                    For initial testing purposes, I think these would be great.
                    I just got one myself. My thoughts...It would be less of a loss to blow one of these up during testing rather than an a more expensive amp/receiver. Yes I do double check everything. But accidents do happen.

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                    • #40
                      Re: New Lepai amps?

                      There are 5 Lepai amps available at PE now. I have many of the original one and I have one of the 2.1 and one of the 4x45 amps.

                      My impression of the 2.1 is that it isn't bad for near field listening and hoping a larger power supply will bump it's output a bit. I was using it with a pair of 3" full range satellites and the 6.5" buyout sub.

                      My first 4x45 had a broken speaker terminal so it was promptly replaced by PE. The second one I have so far tried with my Ipod using the RCA inputs and I have tried to use the FM radio. The antenna that ships with the amp for FM is useless and it uses an RCA jack for its connection which is not standard for any FM antenae I have ever seen, so good luck finding one that will actually pick up any channels. It appears that you can store channels to memory locations, but since the minimal instructions that come with it are in Chinese I haven't figured out how yet. I also can't figure out if there is a way to manually tune to a specific channel and the scanner never seems to detect any channels. So in a nutshell, either the FM portion of mine is defective or it's the worst FM tuner I've seen. I haven't tried the SD or USB functions yet. Using the RCA inputs, sound output to four channels is probably similar in SPL as the original was with 2 channels. It sounds different than the original, but I haven't put my finger on why yet. It just seems softer, more laid back. The remote must be on just the right angle and seems to have a limited range, but is nice to have.

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                      • #41
                        Re: New Lepai amps?

                        For its intended use of moderate quality, non-critical listening, the amp does just fine with the included power supply.

                        That deserves a repeat.

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                        • #42
                          Re: New Lepai amps?

                          Originally posted by [email protected] View Post
                          For its intended use of moderate quality, non-critical listening, the amp does just fine with the included power supply.

                          That deserves a repeat.
                          Yes, I agree, you get more than what you paid for but expect no high fidelity. I am happy with the 4x45/FM unit I purchased. It is what it is....

                          I did expect a manual though that is a printed attempt at english rather than chinese charecters but I have figured out most of what I want to know except I cannot figure out how to preset the channels. While on the subject of the FM reception, it is terrible, I have even used an FM booster antenna and it will pull in only a few channels but none of the ones I want to listen to :-(

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                          • #43
                            Re: New Lepai amps?

                            maybe its designed to recieve chinese FM stations (lol..jk)

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