A new build 15 watt spitfire

[mehfuzhoss]

Hello,

The hi / lo input has 68k on the v1. how different value would affect its sound and by how much pleaese narate elaborately,.

The prev build was a lite 2. I want this one to be more sparlky and fat/round sounding.

Plz share your expertise. Im ordering parts. I will use 1750Y OT and 290bx PT. Will i need a choke for must or i can skip for a low watter amp. Plz tell me about how B+ shpuld be set at. Is VVr an usable option?

I use a Mastet volume in lite 2 and either its off or loud to get OD.

Thanks

[Bieworm]

Why downgrade from 18w to spitfire ? You will likely be disappointed

[TriodeLuvr]

The two 68K resistors form a 6 dB voltage divider when Input #2 is used. That's all they do. This isn't the amp to build if you want breakup. Not enough gain.

Jack

[zaphod_phil]

Why downgrade from 18w to spitfire ? You will likely be disappointed

Well-stated! The Spitfire can be very ice-pick trebly. It's Vox-style PI cathode resistor value cold-biases the PI and therefore tends to give a fizzy breakup. Stick with an 18W for plenty of sparkle and fat/round low end.

[zaphod_phil]

Hello,

The hi / lo input has 68k on the v1. how different value would affect its sound and by how much pleaese narate elaborately,.

The prev build was a lite 2. I want this one to be more sparlky and fat/round sounding.

Plz share your expertise. Im ordering parts. I will use 1750Y OT and 290bx PT. Will i need a choke for must or i can skip for a low watter amp. Plz tell me about how B+ should be set at. Is VVr an usable option?

I use a Mastet volume in lite 2 and either its off or loud to get OD.

Thanks

Generally, a "Mastet Volume" doesn't work with 18W Classic and Lite 2 amps, as most of their distortion comes from the power stage. A VVR will be much more effective.

I prefer to use 10k for the input resistor to improve the top-end sparkle. 68k is an old F*nder value.

Marshall 18W-style amps don't use a choke. A choke will make your amp feel more compressed and "squishy", while also causing power tube screen voltages to be too high.