Hi amigos,
Let me share my last DIY amps. I will review it on this thread soon :
TPA3251d2
@Left : TPA3251 high end PFFB board based on 360 Customs design / TI + handcrafted SMPS PSU.
@Right : Double Mono Ncore NC250MP amp
Enclosures are made in Aluminium for the front and back panels and anti-scratch steel for the Top and Bottom covers with the following philosophy: "a digital amplifier in a vintage analog box"
Let me share my last DIY amps. I will review it on this thread soon :
TPA3251d2
@Left : TPA3251 high end PFFB board based on 360 Customs design / TI + handcrafted SMPS PSU.
@Right : Double Mono Ncore NC250MP amp
Enclosures are made in Aluminium for the front and back panels and anti-scratch steel for the Top and Bottom covers with the following philosophy: "a digital amplifier in a vintage analog box"
Thanks. It is a preventive measures to avoid EMI inspired by the newclassD cookbook. (See their site)
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Hi All,
Just assembled, very first Purifi amp powered by the brand new Micro-Audio SMPS with PFC function.
Final check, finalizing details and then soon to play music ;-)
Just assembled, very first Purifi amp powered by the brand new Micro-Audio SMPS with PFC function.
Final check, finalizing details and then soon to play music ;-)
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
I participated in this 3e-audio group buy almost two years ago. I've been sitting on a EAUMT-0140-2-A (tpa3251 stereo amp board) and a EAPST-0200-36-A (36V/200W SMPS) since early 2019. I've also been sitting on the enclosure for longer than I can remember (it's a "2205" aluminum enclosure, readily available from multiple sellers on ebay). I finally got the motivation to put it all together. It fired up perfectly the second time - the first time I accidentally had the polarity of the DC power supply swapped! (I wasn't paying attention, the supplied cables used black for positive and red for ground; I should have known better than to make assumptions about the color convention.) Fortunately, powering up with polarity reversed doesn't appear to have caused any damage. Once I corrected that mistake, the amp worked exactly as expected. I've had it running continuously for about a week now without issues.
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Thanks Eric! I didn't do any critical listening tests, just used it in my office for quiet background music. I did turn it up a bit a few times, and certainly found the music engaging. The permanent amp for this role is my Modulus-86. I've been working from home since mid-March, and literally have music playing all day, every day in my office. So my "baseline" is the Mod86, and having using the 3e tpa3251 in its place for the last week, I would certainly be happy with either.
I do have a bit of bias in favor of the TI TPA chips, as the tpa311x was what really got me into diyAudio in the first place. So I fully admit to an inability to be impartial when it comes to these class-D chip amps.
Looks great Matt!
I see that you are using just the ballanced inputs, did you build a preamp too, or how do you control the source/volume/EQ?
Got the same amp PSU and the ADAU1701 board with BT4.2, sitting/playing in a drawer since arrived (long time). The reason is that the SMPS has a disturbing high pitched coil wine at all times. Do you happen to get this issue too?
The amp sounds clean, good amount of power. But the ADAU1701 DSP board has low quality ADC capability, messing up the analog signal, so, good only for BT and I2S signal procesing.
KR,
Larry
I see that you are using just the ballanced inputs, did you build a preamp too, or how do you control the source/volume/EQ?
Got the same amp PSU and the ADAU1701 board with BT4.2, sitting/playing in a drawer since arrived (long time). The reason is that the SMPS has a disturbing high pitched coil wine at all times. Do you happen to get this issue too?
The amp sounds clean, good amount of power. But the ADAU1701 DSP board has low quality ADC capability, messing up the analog signal, so, good only for BT and I2S signal procesing.
KR,
Larry
Here is a build from one of my very happy customers using my GaN amp modules.
https://orchardaudio.com/shop/ols/products/bosc-amplifier-module
https://orchardaudio.com/shop/ols/products/bosc-amplifier-module
Attachments
Nice job
Tell us more about you GaN amps ? Some spec ?
Seems really cool.
Hi, the modules are completely my own design no off the shelf modulators or class d chips.
Specifications and test results all posted here:
Orchard Audio - Audio Power Amplifier, Home Audio, Home Stereo System | Orchard Audio - scroll down to see all of it.
Here are the specifications copied from my website:
- Gain: 16.8dB or 6.92
- Signal to Noise Ratio (SNR): 121dB (A-weighted)
- Residual Noise: 32uV (A-weighted)
- THD @ 10W: <0.0003% (-110dB) for 1kHz into 8Ω
- THD @ 0.25W: <0.0030% for 20Hz - 20kHz into 8Ω
- THD @ 10W: <0.0013% for 20Hz - 20kHz into 8Ω
- THD @ 75W: <0.0050% for 20Hz - 20kHz into 8Ω
- THD @ 150W: <0.015% for 20Hz - 20kHz into 8Ω
- THD @ 10W: <0.0004% (-108dB) for 1kHz into 4Ω
- THD @ 0.25W: <0.0030% for 20Hz - 20kHz into 4Ω
- THD @ 10W: <0.0025% for 20Hz - 20kHz into 4Ω
- THD @ 75W: <0.0092% for 20Hz - 20kHz into 4Ω
- THD @ 150W: <0.015% for 20Hz - 20kHz into 4Ω
- Frequency Response: DC - 80kHz+
- Sensitivity: 5Vin for 150W into 8Ω
- Sensitivity: 3.5Vin for 150W into 4Ω
- Input Impedance: 5kΩ fully balanced
- Output Power: 150Wrms
- Damping Factor: >550 @ 1kHz
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The input connectors are indeed XLR. On the amp PCB itself, there is a jumper for each input to select balanced or single-ended mode. In my office, I was using a Topping D70 for input, which has differential outputs. In that setup, I use one of two sources: one, a Raspberry Pi, as a dedicated music player, for playing from my CD collection; the other is Bluetooth, when I stream from my PC.
With the RPI, the connection is USB, and the Topping D70 exposes the AK DAC chip's built-in digital volume control. IOW, controlling volume through the RPI is actually doing hardware volume control in the digital domain. If I'm going to do critical listening, it's via the RPI.
When streaming over Bluetooth, volume control is simply software based. That's the definitely-not-for-critical-listening arrangement - but it dominates for convenience!
I've since moved the amp to the basement, and am now using a Topping DX3 Pro as the DAC. This has only single-ended output, so I use RCA to XLR cables, and changed the amp jumpers accordingly. At the moment, this basement area is being turned into kind of a family room, so convenience necessarily rules there, i.e. Bluetooth will be the primary source. I have another RPI, so I'll probably add an additional dedicated player.
Got the same amp PSU and the ADAU1701 board with BT4.2, sitting/playing in a drawer since arrived (long time). The reason is that the SMPS has a disturbing high pitched coil wine at all times. Do you happen to get this issue too?
Hrm, that is strange. My SMPS has a very slight hiss, it's only noticeable with the case lid removed and my ear right by the PSU. WIth the lid on, and my ear more than a foot or so away, it's inaudible.
The Topping DX3 looks like a capable DAC. I learned that BT over LDAC codec it is almost up there with the analog cable quality. True story?
Also, do you feel the switch from the XLR to single-ended RCA? Floor noise, hum, imaging?!
I'm trying to find a covenient way to input analog signal (ex:turntable) and not cripple the signal in the digital conversion, then also BT, SPDIF (for Rpi or maby be a streamer too)... into the amp that you build, and all the sources to be volume controlled from this magical device, maby not breaking the bank in the process. It think people call it "unicorn"
or a DieHard DIY session 
Larry