Friedman Twin Sister demo

Friedman amplification have taken the humble Marshall JTM45 and given it a buff!

Actually it's the Dirty Shirley model which is the single channel version that has JTM45 genes; this is a buff on the Dirty Shirley and is, apparently, her Twin Sister.

Like the Dirty Shirley, this is a valve rectified 40 Watt amplifier with a complement of 2 valves per channel for the pre amp, a shared phase invertor and a pair of 5881 valves in the power section with a 5AR4/GZ34 as a rectifier. Having 2 identical channels, this has five 12AX7 or ECC83 as we like to call them in the UK including the phase invertor which is used to split the single 180 degrees out of phase to feed the current through the primary of the output transformer for a push/pull arrangement.

It also has an extra deep control to allow the bass resonance to be adjusted for extra 'thump' and other wise the same control set as the Dirty Shirley. So, from left to right we have a shared 'presence' which I think is a negative feedback adjustment pot and this deep control. These are shared by the 2 channels. Then there is Bass, Middle and Treble for EQ and a Master volume and channel gain.

I think the Master must be a post Phase Inverter style and it works really well. You actually don't need an attenuator for this as it's an excellent implementation. As suggested in the comments, it might be pre phase inverter though. I don't have a circuit diagram.

It has a series FX loop and I am using my Surfybear reverb tank into it. Works very well.

The back has impedance selection for 4/8 and 16 ohm cabs and a footswitch to switch channels is under the main guitar input.

I'm using a 2010 Gibson R7 gold top and going straight in. Just the reverb unit in the FX loop and mic'ed up with a Rode NT1-A and an SM57 using my AF Custom cabs 2x10" Fender style cab with two Eminence Legend 1028k speakers.

It's a 4 ohm cab and I'm using the Tone king Ironman II to transform impedance from 8 ohm to 4 ohm. You can change it on the back of the amp to 4 ohm but I wanted to take off a bit of volume too.

UPDATE: sadly this is being returned. I was getting volume fluctuations randomly and had been testing it with a looper and swapping out the valves I could with new ones. The rectifier and all the pre amp valves were changed and it would still suddenly lurch in volume. Then it started popping. Probably the 5881s but I'm out frankly. Head and cab are being returned. The soldering in the cab was woeful!

Visit my website for more demos and stuff https://www.gringopig.com/

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