Elekit TU-8500DX 12AU7 Pre-Amplifier Kit
The TU-8500 is an exceptionally well designed pre-amplifier kit including phono stage. This is a special edition exclusively for the diyAudio store that includes 5% AMTRANS carbon 1/4 W resistors.
The front features a power switch, volume control and 4 way input selector (Line 1/2/3/Phono).
The rear features a pair of RCAs for each input of Line 1, 2, 3 and Phono, and pre-out. There's also a 3.5mm jack bound to Line 3. Switches are offered for MC/MM cartridge selection and a unity gain toggle switch for use with sources that already have enough gain.
It's a perfect match for the TU-8200 power amplifier.
Phono stage features:
- Precision RIAA equalization (CR not NF)
- Supports both MM and MC cartridges
- Low noise Opamps using sockets to allow for the easy substitution of alternative Opamps
Line stage features:
- Two 12AU7 (ECC82) tubes
- Switchable unity gain or 3x gain
- Reduced hum/background noise circuitry
- Low flux leakage R-core transformer
- FET ripple filter for B-power
- Tubes powered by the DC power supply
- DIY friendly PCB with room for larger coupling capacitors
- 100/115/220/230V input voltage selectable during assembly
- Phillips screwdriver
- Diagonal cutter
- Longnose pliers
- Scotch tape
- Hex wrench
- Soldering iron
- Stock tube: 2 x 12AU7 (ECC82)
- Opamp: 2 x NJM2068DD
- Dimensions: 252 x 73 x 270mm including projections
- Weight: ~3.1kg assembled
- Line stage
- Gain: x3.1 (9.8dB) / x1.15 (1.2dB) selectable
- Frequency Response: 2Hz-70kHz / 2Hz - 280kHz (-3 dB)
- SN ratio (IHF-A): 122dB / 129dB
- Max Output Voltage: 22V rms (1kHz)
- Phono equalizer stage
- RIAA equalization: +/- 0.5dB tolerance (20Hz - 280kHz)
- Cartridge: MM / MC selectable
- Gain (1kHz): MM 37dB / MC 63dB
- SN ratio (IHF-A): MM 108dB / MC 88dB
- Input resistance: MM 50kΩ / MC 100Ω
- Max output voltage: 7.4V rms (1kHz)
- Audio Inputs
- Phono (2 x RCA)
- Line 1 (2 x RCA)
- Line 2 (2 x RCA)
- Line 3 (2 x RCA or 3.5mm jack)
- Audio Outputs
- Pre-Out (2 x RCA)
- Input Power: 110/115/200/230V via IEC inlet
- Included tubes: NOS GE 5965
Fun build and I love the soundquality from this preamp.
I would like som xlr outputs.
Pros: very quiet, even although somewhat veiled transparency
Cons: not tubelike, no xlr connection
Directions were thorough. A lot of parts, but can be done by a careful nubie, this being my third soldering project. Everything fit together well. Sounds good so far, but I haven't tested it with a fancier setup.
One thing that wasn't clear though, was the extra bags of resistors. I didn't realize the Amtrans upgrade means you have a whole extra set of resistors, I had to desolder a few after I figured out what was going on.
Previously I had built a $17 amp and preamp with speakers. HA! It had a zillion resistors. I just took on the challenge of the TU 8500 hoping I could do it. I followed the directions closely, everything worked perfectly the first time! Exceptional!
2nd DIY amps from diyaudio. All seemed easier than the first time. PCB design is beautiful, instruction is clear enough. Very happy to have both preamp and pw amp (amp camp amp) done by myself. Thank you very much for your site, will plan the next shopping here, maybe a tube amp.
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