These tests were carried out using my own Brian May replica guitar.
The pedals were played through a VOX AC30 Normal Channel.
 

Treble Booster

The Treble Booster was used between the guitar and the amplifier.
Using the AC30 Normal Channel, and the volume up full, I instantly recognised a familiar Brian May sound.

What I found unique was the ability to go for a full-blown heavy rock sound, with warmth, to a beautiful "tinkling" clean sound by just turning the volume control, of the guitar, to a low level.

Using the out of phase settings on the guitar produced that "whiney" tone that is obvious on the Red Special.
The feedback was unusual. At full guitar volume, the guitar easily lifted off into feedback which then travels upwards in octaves! Providing your pick-ups have been waxed you should not suffer too badly with microphonics. I used string damping for the rhythm work to give it a really chunky sound.

Overall, the pedal produced a warm and creamy-smooth distortion that could be shaped, to personal taste, by the gain control on the pedal or the volume control of the guitar.

Ringmaster

The Ringmaster was used between the guitar and the amplifier. Again, the pedal was used between the guitar and the AC30 Normal Channel at full volume.
I have long been a fan of the original Brian May sound from the first few albums.
This pedal uses the Germanium transistor as opposed to the Silicone one. There is an obvious rawness to the sound, which is obvious on tracks like "Brighton Rock" and "Modern Times Rock And Roll". It offers a similar amount of distortion to the Treble Booster and is equally as quiet.

I found that the sound was "hollow" in comparison to the Treble Booster. It had certainly captured the early sound very well. The "hollowness" is very prominent when you produce feedback for sustaining notes. The gain control, again, gives you the same versatility as the Treble Booster.
Using the volume control on the guitar I, again, was able to change from a full distortion sound to a crisp clean sound. There is still warmth in the sound but there is an obvious edge to it.

If you are a fan of the very early Brian May sound, then this pedal will be just right for you.

Please note that I used the AC30 at full volume in a practice studio. That level of volume could render everyone in your street deaf and also remove your windows!
 

Mayhem

These tests were done using the suggested settings on the Fryer information sheet provided with the pedal.
 

The Deacy Amp setting

The guitar is plugged, first, into the Treble Booster and then through the Mayhem pedal to the amplifier.

Using the settings suggested by Mr. Fryer, I found that the sound was very reminiscent of the Deacy Amp. It is a strange "boxy" sound that is unusually warm and heavily distorted. I found it very easy to sustain notes all over the fretboard.
Using the different in and out of phase settings on the Red Special, you begin to hear which songs the Deacy Amp was used on. I have actually played my guitar through the original Deacy Amp and I was very impressed with this pedal for it's ability to produce such a unique sound. It was close to the original sound, as I remember it.
 

VOX AC30 overdriven sound

The beauty of this setting is that you do not have to run the AC30 at full volume.

The Mayhem is still used with the Treble booster.

The Mayhem pedal is very powerful and the AC30 performed in a very similar way to being at full volume. The warmth is retained and the feedback still functions in a similar way.
I found that experimenting with the different settings you could get a wide variety of distortion sounds with that creamy-smoothness to it. This pedal is very versatile and would be very useful to a "home" musician wanting that "BIG" sound at lower volume.

I personally use a Marshall Valvestate 8080 amplifier. I did try out the pedals through that.
With a little playing around, with the amplifier and pedal settings, I was able to get some very satisfactory results.
The only thing that I thought was lacking was the sound was a little raw and lacked the warmth of a true valve amplifier.
The Treble Booster worked well as did the Ringmaster. I was able to get very close Brian May sounds using those.

The Mayhem was a little harder to set up. I put it through the clean channel on a crunch setting (in the same way, with the Treble Booster). I did manage to get a very good Deacy Amp sound that I would have been happy with.
Using the Mayhem for a distorted sound also worked out well. It was very useable but you have to be careful, as the Mayhem is very powerful. It drives the amp hard at low volume so you do not need as much volume as you think for it to be loud!

 I feel that Greg Fryer has totally captured all the aspects of Brian May's sounds in these pedals. He has certainly put into these products what we all recognise as Brian May. Anyone wanting to obtain those sounds would not go far wrong by purchasing any of these pedals.
After all, Brian May uses them!