SOLD: Neurochrome DIY DG300b stereo 300b SET amplifier
SOLD
I love the sound of this amplifier, but significant changes to my listening area make this incompatible with my other components.
This is an unusual SET amp in that it has balanced inputs with input transformers for galvanic isolation and ground loop abatement. You certainly can use RCA inputs with RCA to XLR adapters.
Gain is low, and you will need about 4.2 volts input to get the amp to full output. You will need a preamp with some gain for best results.
The output is set for 8 ohm speaker resistance, but I can change it to 4 or 16 ohm if you need that.
This is the the most noise free implementation of a SET amplifier I have ever had. There is a small amount of mains transformer hum audible with your ear within a foot or two of the amp, but is not of consequence. There was no noise audible through my 95db sensitive speakers with the amp on. Great stereo separation and SET midrange with a surprisingly tight bass output. The amp takes about 30 minutes to get to steady state, but sounds great even when first turned on. It runs HOT, with all the regulation and 4 tubes, chassis and heatsink temps get to about 55 degrees C., so the amp needs good ventilation for long life of the components.
All Neurochrome supplied boards of the last available revision are used.
DG300B | Neurochrome :: Audio
All parts used are those as specified in the BOM for each board. I did upgrade the coupling capacitors to Sonicap Gen 1.
The amp has slow turn on, with the filaments on for about 30 sec before the diode regulated B+ comes up. This is a very well engineered amplifier by Ton Christiansen of Neurochrome.
Power transformer is a huge Classic Tone 40-18069, and the OPTs are the One Electron UBT-2. All are from the same transformer manufacturer, Magnetic Components, Inc.
B+ power is regulated at 400vdc to the signal boards, preamp filament supplies are voltage regulated to 6.3 vdc and 300b filament supplies are voltage regulated to 5.0 vdc. The 300b tubes are fixed bias, not the typical cathode biased, and even that supply is regulated.
The amp is configured to use ecc88/6922 preamp tubes.
Output is about 10 watts / channel at the specified 400 vdc supply power and 85mA cathode current.
If you are comfortable and able to work around HIGH Voltage in an amplifier, there is room to adjust the B+ and 300b bias setting.
The amplifier is built on a Landfall Systems 18 x 15 inch chassis, which is a really nice chassis. The faceplate, top plate and back plate all have some superficial scratches in the anodizing as shown.
I rate the amp 7/10 for the DIY nature of the amp and the scratches.
The amp will be supplied with a pair of new, well matched low noise Ecc88 Gold Lion Reissue tubes and a matched pair of Electro-Harmonix 300b tubes with less than 100 hours on all tubes.
Sale includes insured UPS ground shipping to the continental USA. Shipping to PayPal verified addresses only.
Amp weight is about 45 pounds.
SOLD
I love the sound of this amplifier, but significant changes to my listening area make this incompatible with my other components.
This is an unusual SET amp in that it has balanced inputs with input transformers for galvanic isolation and ground loop abatement. You certainly can use RCA inputs with RCA to XLR adapters.
Gain is low, and you will need about 4.2 volts input to get the amp to full output. You will need a preamp with some gain for best results.
The output is set for 8 ohm speaker resistance, but I can change it to 4 or 16 ohm if you need that.
This is the the most noise free implementation of a SET amplifier I have ever had. There is a small amount of mains transformer hum audible with your ear within a foot or two of the amp, but is not of consequence. There was no noise audible through my 95db sensitive speakers with the amp on. Great stereo separation and SET midrange with a surprisingly tight bass output. The amp takes about 30 minutes to get to steady state, but sounds great even when first turned on. It runs HOT, with all the regulation and 4 tubes, chassis and heatsink temps get to about 55 degrees C., so the amp needs good ventilation for long life of the components.
All Neurochrome supplied boards of the last available revision are used.
DG300B | Neurochrome :: Audio
All parts used are those as specified in the BOM for each board. I did upgrade the coupling capacitors to Sonicap Gen 1.
The amp has slow turn on, with the filaments on for about 30 sec before the diode regulated B+ comes up. This is a very well engineered amplifier by Ton Christiansen of Neurochrome.
Power transformer is a huge Classic Tone 40-18069, and the OPTs are the One Electron UBT-2. All are from the same transformer manufacturer, Magnetic Components, Inc.
B+ power is regulated at 400vdc to the signal boards, preamp filament supplies are voltage regulated to 6.3 vdc and 300b filament supplies are voltage regulated to 5.0 vdc. The 300b tubes are fixed bias, not the typical cathode biased, and even that supply is regulated.
The amp is configured to use ecc88/6922 preamp tubes.
Output is about 10 watts / channel at the specified 400 vdc supply power and 85mA cathode current.
If you are comfortable and able to work around HIGH Voltage in an amplifier, there is room to adjust the B+ and 300b bias setting.
The amplifier is built on a Landfall Systems 18 x 15 inch chassis, which is a really nice chassis. The faceplate, top plate and back plate all have some superficial scratches in the anodizing as shown.
I rate the amp 7/10 for the DIY nature of the amp and the scratches.
The amp will be supplied with a pair of new, well matched low noise Ecc88 Gold Lion Reissue tubes and a matched pair of Electro-Harmonix 300b tubes with less than 100 hours on all tubes.
Sale includes insured UPS ground shipping to the continental USA. Shipping to PayPal verified addresses only.
Amp weight is about 45 pounds.
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Ditto, I've been holding my breath hoping someone would grab it before I broke down.
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