– part 2 of 2
…it’s a hateful thing that only adds fizz and harshness
As you can see from part 1 of this article, there was no honeymoon with the Flexi, it was more akin to learning to love something with time and familiarity. I also believe that it’s a good idea to stick with the equipment you buy for some time before you conclude that it needs replacing, but that’s a topic for another post.
I’ll now try to demonstrate the sounds you can get with the Flexi. After pretty exstensive searching on the web and on YouTube, I’ve found that there are lots of descriptions and demonstrations of the operational aspects of the Flexi – boost function, ability to use multiple tube types, and so on – but clips that give a good representation of the amp’s tone are thin on the ground. Granted, there are quite a few clips. This one with Chris Poland is entertaining, but it demonstrates Chris’ superlative playing a lot more than it demonstrates the amp. The technical quality of the clip is wanting, and doesn’t do the Flexi justice. Other examples have OK recording and sound quality, but the people who demonstrate the amp don’t seem to have any clear idea how to get the best sounds from it (I’ll spare you these. They are plentiful, however). And why are there no properly recorded, volume-equalized tests of how the bloody thing sounds with different tubes? It’s one of its key features, and it’s also one of the first things mentioned in any write up, but so far no good-quality clips that actually lets you as a viewer make a qualified decision whether you like it or not (at least I haven’t been able to find any). Hopefully, this article will go some way in restoring the balance.
In the clips below I’ll be demonstrating what I think of as the Flexi’s natural tone. I’m running mine in 50 watt mode, boost on, and EQ and other settings as in the pictures. I’ve got two 12ax7’s and one 12at7 in the preamp. I’ve done three clips of the amp with EL34 output tubes, and three with 6L6’es. The first pair are with the master volume switched in. The second are with the master volume switched out, but with the THD Hot Plate attenuator bringing the sound pressure down to acceptable levels. The two last clips are of the amp at full volume.
Astute viewers will have noticed that I’ve turned the CUT control all the way down. The reason for this being that it’s a hateful thing that only adds fizz and harshness, and I hardly ever turn it up.
Another interesting thing about the Flexi that no one writes about in any depth is the two gain controls: volume, and boost. Yes, people mention the boost, but they focus on that it’s footswitchable, which I personally never had much use for, although I’m sure there are others who use it to great effect. The important bit is that these two gain controls are in different parts of the circuit, and therefore have very different characteristics. The volume control is first in the circuit, so it responds differently from the boost, which is later in the circuit. The volume control sets the basic dynamic response of the amp, i.e. how much the amp compresses. It also darkens the tone as you turn it up, and in tandem with more compression this gives a progressively fatter, but softer tone. The boost control, however, boldens the tone as you turn it up, and adds crunch. In a way it tightens up the low end and gives a more high-mid emphasis to the tone. In short, it adds aggression and attitude. How you set these controls influences the sound of the amp a lot more than the tone controls do, and getting to know these two knobs and the way they interact is one of the secrets behind getting this amp to sound at its best, in my opnion.
You can use almost any power tube in the Flexi, as long as it physically fits in the socket. I haven’t experimented with the more esoteric tube variants, but I’ll try to give you an impression of how much – or how little – difference changing between 6L6’es and EL34’s will make. To make sure that we’re doing a comparison that can actually tell us something, I’ve done a couple of things to highlight the characteristics of each tube type:
- All the clips are volume-equalized subjectively. Meters only tell you so much, and to avoid us favouring one clip over another on account of it being subjectively louder, I’ve equalized their relative volume so that to me when A/B’ing between the clips, there’s no discernable volume difference.
- Both tupe types are biased to show 32 mV on a digital volt meter. For background information on tube biasing, I suggest asking Google.
- I’ve done three different tests with different volume settings. The first is with the master volume at 01.30; the second is with the master volume switched off, but with a THD HotPlate set to yield the same subjective volume in the room as the first. Finally I’ve done clips with the amp wide open. Hopefully we can hear differences in the way the power tubes compress and distort differently under different conditions.
With master volume:
With Hot Plate, no master volume:
And finally, wide open:
Who do you love?
Hopefully I’ll have succeeded in showing the different nuances the tube types give. Interestingly, to me the difference between master volume/no mastervolume, and attenuated/not attenuated makes a bigger difference than the tube types, although they do differ somewhat. A few observations:
- Of all the clips, my least favourite is the attenuated version – regardless of tube type. This is clearly a compromise, and it both sounds and feels constipated, for lack of a better word. In this regard there is not a huge amount of difference between the experience in the room, and the recorded version.
- I prefer the clips with the master volume engaged, although the perceived difference is a lot bigger listening back to the recording. In the room it would have been impossible for me to point to specific differences between the tube types apart from the fact that the 6L6’es were noticeably louder for a given master volume setting.
- Playing this amp in a 10 square meter room at full volume is a guaranteed to cause substantial hearing loss in a matter of minutes – and we’re talking single-figures here. I had to wear heavy-duty hearing protection while recording, and as I’ve mentioned earlier, even death metal drummers can’t compete volume-wise with this. Needless to say, recording while monitoring on headphones is not realistic, so this is just for the sake of science. Real-world usability in this setting is nil. It should be mentioned that the visceral pleasure of feeling the thump in your chest and the sheer interactive response between the guitar and the amp is pure euphoria, although my Mac’s hard drive was sufficiently rattled during recording to cause system freeze (yes, it sounds improbable, but I tried close to ten times with alternating high and low volume, and the correlation between system freeze and loud volume was strong enough to be convincing).
- Disappointingly, the amp wide open is not my favourite sound, and my theory is that it’s the intoxicating effect of sheer volume, not tone quality that is at least in part reason for the urban legend that tube amps have to be turned up to max to sound their best (yes, I’m extrapolating – clearly I haven’t tried all other tube amps). The fact that the amp wide open with EL34’s seems to add some high end, while the same setting with 6L6’es seems to dull the amp slightly, is interesting, and I’d love to hear from you in the comments section if you have any idea why this is, and if it’s a feature with this amp but not with others.
To my ears there are noticable differences between the tube types, and between the response types you’ll get at different volumes. They are not big enough, in my opinion, to warrant running out and buying lots of different tubes to give you “a whole new amplifier” – this is marketing hyperbole. At least with these tube types, it still sounds and feels like a Flexi, and you could get equally significant results with microphone placement alone, and/or different volume settings.
What are your impressions? Let me know in the comments section. Thanks for reading.