So, its been little over a month since I finished building the amp and I guess an update is in order.
Firstly, the 'problem' on the Superlite channel turns out to be rather normal hiss coming from the valves. That channel is very gainy and when you turn the preamp and master volume up to 10 all the valves are giving it their all and the hiss can be heard. This can be minimised by carefully selecting low noise valves for the preamp and phase inverter positions (V2 and V3 for this channel). Something to try in future maybe.
Secondly, these 18 watts are prone to something called the 'Paul Ruby Buzz' is a kind of fizziness that can be heard when you turn the volume up to make the EL84s drive a lot. The fizz changes it's frequency depending on the signal strength so on long sustained notes it can be heard as a phasing type sound. Mine did this too and seeing I play it highly driven all the time I fixed it by installing a Zobel filter on the speaker side of the Output transformer. Simple R10 mod consisting of a Resistor and Capacitor in series between the two wires going to the speaker jack. Now its a bit darker sounding and the fizz is only just audible. IF you don't know what to listen for you won't know its there. It has something to do with blocking distortion and grid currents and some cap charging when its not supposed to. Magic. I fixed it.
Thirdly. The amp has now been used at a couple of Hellfire's gigs by Singemonkey. Unmic'd it has not been used at more than about 8 watts at any of the gigs. If 18 watts is not enough for you to gig with there's something wrong somewhere (with your band/drummer/ears....), unless you play funk, but thats another thing. Having a non-master-volume amp of 20 watts or more without the power scaling option is a complete and utter waste of time. You will have to resort to pedals to get the amp to drive at a reasonable volume and that would be a very sad thing indeed. The guy that got me into building this amp warned me that this amp ruined many other very good amps for him, and I can honestly say the same thing happened to me.
The simplicity is a joy. I put two channels onto the amp because I was afraid that a simple channel with only two knobs will not be versatile enough and you will be severely limited in your options, not so, thus far I and Singemonkey have used this amp only on the Lite IIB channel, put the Tone on 8, Volume on 8, do the rest from the guitar. Need more drive? Step on the tubescreamer. Need clean? Turn the guitar down a bit. Although, on its own there's quite a hefty amount of overdrive with humbuckers. Setting it up at gigs involves plugging it all in and turning the VVR knob until the desired volume is reached. No mess no fuss.
Although only 18 watts and with the VVR installed the amp is still too loud for night playing. It really wants to run loudly, the speakers are happy then and so are the valves when they get proper voltage to work with.
Singemonkey can tell you more, he has more experience playing it in a live setting (He sure had lotsa fun with it on Wednesday night!)
Firstly, the 'problem' on the Superlite channel turns out to be rather normal hiss coming from the valves. That channel is very gainy and when you turn the preamp and master volume up to 10 all the valves are giving it their all and the hiss can be heard. This can be minimised by carefully selecting low noise valves for the preamp and phase inverter positions (V2 and V3 for this channel). Something to try in future maybe.
Secondly, these 18 watts are prone to something called the 'Paul Ruby Buzz' is a kind of fizziness that can be heard when you turn the volume up to make the EL84s drive a lot. The fizz changes it's frequency depending on the signal strength so on long sustained notes it can be heard as a phasing type sound. Mine did this too and seeing I play it highly driven all the time I fixed it by installing a Zobel filter on the speaker side of the Output transformer. Simple R10 mod consisting of a Resistor and Capacitor in series between the two wires going to the speaker jack. Now its a bit darker sounding and the fizz is only just audible. IF you don't know what to listen for you won't know its there. It has something to do with blocking distortion and grid currents and some cap charging when its not supposed to. Magic. I fixed it.
Thirdly. The amp has now been used at a couple of Hellfire's gigs by Singemonkey. Unmic'd it has not been used at more than about 8 watts at any of the gigs. If 18 watts is not enough for you to gig with there's something wrong somewhere (with your band/drummer/ears....), unless you play funk, but thats another thing. Having a non-master-volume amp of 20 watts or more without the power scaling option is a complete and utter waste of time. You will have to resort to pedals to get the amp to drive at a reasonable volume and that would be a very sad thing indeed. The guy that got me into building this amp warned me that this amp ruined many other very good amps for him, and I can honestly say the same thing happened to me.
The simplicity is a joy. I put two channels onto the amp because I was afraid that a simple channel with only two knobs will not be versatile enough and you will be severely limited in your options, not so, thus far I and Singemonkey have used this amp only on the Lite IIB channel, put the Tone on 8, Volume on 8, do the rest from the guitar. Need more drive? Step on the tubescreamer. Need clean? Turn the guitar down a bit. Although, on its own there's quite a hefty amount of overdrive with humbuckers. Setting it up at gigs involves plugging it all in and turning the VVR knob until the desired volume is reached. No mess no fuss.
Although only 18 watts and with the VVR installed the amp is still too loud for night playing. It really wants to run loudly, the speakers are happy then and so are the valves when they get proper voltage to work with.
Singemonkey can tell you more, he has more experience playing it in a live setting (He sure had lotsa fun with it on Wednesday night!)
I am very jealous, and damn that amp is screaming with tone... very good job indeed! 
