The Amp Garage

Gotta be an early silverface-that's still a pretty neat wiring job. I think the stamp in the chassis saying 11th week of 1968. First production year of the silverface bandmasters. Inside all blackface items, no spaghetti and the famous AA768 circuit. Mint condition. A keeper! Yes, recommend OT from...

I really enjoyed your postings. I just wanna emphasize the importance of matched tubes (PI). If not both triodes have the exact amplification curves, the whole adjustment makes no sense. And each called adjust method is getting you closer to the perfect balance. But there is no perfect balance. At l...

@gary The primary of the OT is fix. It's just depending on the type of tube (or how much tubes you use in the power stage). It's in the data sheet called load resistance necessary between Anode and Anode. The impedance is a more complex thing. It's the resistance depending on the frequence (includin...

Phil is right. The word is load resistance . In the data sheet of the 6L6 exists a value: load resistance (AB1, fixed bias, tetrode ...) that the tubes expecting when they (sorry) look at the ot. Remember all power tubes are parallel. If the ot was build for 4 6L6 parallel for a 4Ohms speaker, 2 6L6...

Hi everyone!
The bias is one point the matching of tubes is another. With bias adjustment you're looking for the correct working point. Matching means comparing the whole amplifying curves and choosing tubes with similar values (how much is the amplifying factor at Imput 1 Volt, 2 Volts ...)
Tom

My understanding is that for resistors to exhibit this behavior there must be around 100V across them. The NFB resistor does not get near that. See: http://www.geofex.com/article_folders/carbon_comp/carboncomp.htm The geofex article is talking about a sinus wave 100V AC over a 50V DC resulting in a...

Don't want sombody confusing. Sorry, english is not my home language. 1 Watt is enough and stable at this position. Mr. Dumble often choose the bigger 2 Watts because they sound warmer. Resistors: Carbon Compress resistors sound different than carbon film and metal oxide. From warmer to more compact...

Hi Steve! 1 Watt is enough in a electrically manner. But Mr. Dumble is aware of choosing his materials as a sound designer. The 2 watts Carbon Comps are famous for their overtones on big voltage jump positions(and their noise and heat drift too). Nowadays 2 Watts CC are rare and expensive. However t...