Some time ago my son turned 18. He came to me and asked for a stereo set as a birthday present. I said, that I would buy one for him. He replied that I did not understand. What he wanted was a vacuum tube amplifier “built by me”. The only additional requirement was that he should have been able to connect his mobile phone to it, using Bluetooth. This is how the ” 18th Niccolò Anniversary ” originated. I basically used the design of “Il Terzo“, with some modifications, due to the use of a different power transformer, and the addition of a Bluetooth module.
Characteristics:
>>Measures coming soon<<
- Push-Pull stereo integrated amplifier
- Max Output Power 2x ~12W
- @ 1 Volt peak input signal, with 16dB global negative feedback
- Power Stage: 2x 2 EL84 power vacuum tubes in Push-Pull Ultra-Linear configuration and fixed bias
- Phase Split Stage: DC coupled Concertina with 12AX7 vacuum tubes
- Input Stage: 12AX7 vacuum tubes with self bias and bypass capacitor
- Class AB with 28 mA anode current bias
- Output Transformer: Hammond 1650E
- Primary: 8K Ohm C.T., 40% screen tap
- Secondary: 4, 8, 16 Ohm
- Power Supply Unit Transformer: Hammond 370HX 550V c.t@230mA
- Global Negative Feedback: 16dB
- THD (measured with Sovtek 12AX7 LPS + JJ EL84)
- at 1W: TBC
- at 5W: TBC
- at 10W: TBC
- Two only capacitors in the signal path
- 4, 8 Ohm Speakers
- Input Impedance: 100K Ohm
- Output Impedance: TBC
- Damping Factor: TBC
- 3 selectable input sources
- Bluetooth input
Vacuum tube amplifier schema (LTSpice simulation screenshot)
Power supply schema for the vacuum tube amplifier (LTSpice simulation screenshot)
Gallery
Hello, thanks for sharing your projects. I love the fact that you provide measurements to verify your designs and implementations. The fact that you use affordable commercial tubes is also testimony of good design.
Regarding this project, do you expect to measure the same as the Il Terzo project? I think the main difference is the use of a transformer with higher voltage.
And may I ask if it is possible to include equivalent models for Edcor transformers? The company have good reputation with the audio community and appears to be a more cost effective option at least for US customers.
Yes they measure the same.
In fact I should build one with Edcor transformers. Not easy to find them in Europe.
Mr. Amato,
I can appreciate your point-to-point wiring; it is simple and robust. Would you please guide me to a design of yours that is only a POWER TUBE amp without any PRE-AMP construction. I want to hear my guitar modeller without any pre-amp influence. This is the idea behind a high quality combo amp from ATOMIC, as in the ATOMIC Reactor 112. The digital modeller performs the duties of the pre-amp. I would like to build in the 50 Watt range to have more headroom than a 20 Watt amp. An attenuator would also be appreciated in this build so that I may practice at two or five watts and play in public at 20 or 50 watts. I feel that 2 / 15 / 50 would be ideal. Thank you.
Respectfully,
Jeff
Hi,
I do not have any amp design with these specs. Did you find something?