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300b SE Tube amp


justinsweber

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Here is a custom fastlaneaudio/ampsandsound 300b.

Build using the classic method of turret boards this amp is built with the same skill and attention to detail that macintosh and Marantz use. SS rectification, incredible power supply with large 5H choke. Transformers are Transcendar with 200% duty cycle. Freq response is 12z to 28khz +/- 1db. input sensitivity is 1.2v and output is 8watts. The tubes are barely broken in and test new on my hickok tube tester. The 300b's are the amazing Sophia Electric mesh plate 300B globe tubes which are ~$350 a pair and a NOS mil spec tungsol 6SL7. The amp is direct heated triodes with zero feedback. This is the definition of SET/DHT amps. The amp has been fully bench tested and is without issue and can be auditioned on 103db efficient Klipsch La Scalas... its dead silent.

 

$1100 Justin 323-868-9722

 

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Beautiful amp Justin, the Sophia Mesh plates are stunning. Really like the tranny housings as well. 

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Nice amp! A few years back I had a Sophia Electric 300B it was their flagship amp at that time simply beautiful!!! I too used the mesh tubes loved the sound for about four years, then I heard the 45 type!!! Well I have had one of those ever since, the 300b is a great sounding amp except for me it was just a little too lush. Some folks like that though so to each his own, good luck with the sale Justin I am sure someone will love it!!!

Edited by canyonman
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I did much of the case work and Dave did the wiring... Its a stunning amp. The Transformer covers really balance the chassis. I believe its 17x12x3. Outputs on the ends and power and choke on the inside positions. The Amp is has hum adjust pots, but is so quite that it seems un-needed.

Edited by justinsweber
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SS rectification, incredible power supply with large 5H choke. Transformers are Transcendar with 200% duty cycle. Freq response is 12z to 28khz +/- 1db. input sensitivity is 1.2v and output is 8watts.

 

 

 

Justin, is this the amp that Dave had a thread somewhere on the forum where he did the point-to-point turret board of Parks 'Get*Set*Go' schematic with the modifications for the 300b tube instead of the 6B4G tube?  

 

If so, does the switching to the diode rectifiers and losing the voltage drop of the 6AX5GT rectifier give the additional output to 8 watts per channel? 

 

For some reason I keep thinking that with the Parks schematic you would have about 5 watts; however, that may be just with the resistor changes needed for the 300b tube and retaining the tube rectifier rather than the diodes. 

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It is the one Dave showed in his build previously on here. Though based on the GetSetGo, I believe its more than just the removal of the rectifier. 

The Parks 6G4B is about 5watts in SS form. 

I was a bit unsure of the transformer covers when Dave told me about them, but when he showed me the finished product I was in love... Man they look great. 

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