by bordonbert Mon Aug 02, 2021 10:41 am
Hi Robsco, hope I can help. I talk from an early classic rock perspective so I don't know if this will be totally applicable to your own needs. If you are a more modern high gain player or a cleaner country or jazz player it will vary of course.
I use a Bugera PS1 too and think it is a very useful little unit despite the internet trash talk. I found the same as you, with the non-linearity of the ear, for home playing, you really only need a few 100mW or so. You have to slug any amp right down to get a family and neighbour friendly level and you lose tone and feel. I run a few Marshalls up to classic 100W versions too and they universally have no low level to play with at all. The H&Ks like your GM40D are not alone in this, it is a universal problem, but they are better than most with their inbuilt Power Soak of course. Opinion on this problem and solutions do seem to be heavily influenced by a minority of guitarists who think the only method is to just "dime the f**king lot and screw the neighbours". I don't live in that world.
I know my electronics from a career designing in industry and I can at least confirm that the insides of the PS1 are very well designed, as in all of the sums add up correctly, and it has plenty of breathing space to dissipate heat. As I said, just don't thrash it continuously with a 100W high gain amp dimed, treat it sensibly. They are built to a high quality with good high power resistors standing off a well designed PCB utilising high quality soldering. The most delicate area in any power soak like this is the level control. Having highish signal currents passing through very basic wiper contacts can produce problems over time. The PS1 uses the same L-Pad unit, (kind of a double wirewound pot to level out impedance), as many other highly acclaimed more expensive units on the market. I do think that, with high power use like some of my Marshalls followed by much lower power use in my GM36 the sound nowadays thins out a bit at lower powers in a way it didn't to start with. By that I mean using a 20W Marshall SC20H on its 5W setting and about half volume which should mean running about 3-4W into the PS1. That is a fair bit above your own required level so it may not develop as a problem for you. I suspect this may be down to ageing of the L-Pad wiper contacts which will have to run hot at times when used close to 100W. This is not a massively excessive effect but is a factor to consider. For the 40W max of the GM40D it should not be a problem. It only cropped up after quite a while when I started running my higher powered JVM and JCM amps through it.
You will find that some of the problem is down to speakers as well as the amp. The larger the speaker cone radiating area the louder the speaker will sound for all else being the same. That isn't the only factor of course but it does contribute. If you can get your hands on a reasonably decent single 10" or even 8" speaker for home use that will help.
The Bugera will certainly drop the power to your speakers, whatever they are, and bring the volume down. However, it is inevitable that in doing that the tone will change. That isn't just the PS1, that is how it works for even the most exotic and expensive guru acclaimed units out there. Guitar speakers are very different to hifi speakers. For hifi the idea is to produce the most linear reproduction across all levels of cone excursion up to the limit. Contrary to that, guitar speakers have their cones and their mounting systems designed to be driven into their "non-linear excursion" region where the surround cannot extend any further and begins to physically restrict the cone travel. This also produces its own distortion added into the mix. You will lose that with a larger speaker driven through a low power output like the PS1's as it is only driven over a short cone excursion.
Also, some of the great rock guitar sound we love is literally the speakers driving the air in front of them into compression with that producing its own unique contribution to the overall sound. Get down below that level and that distortion source drops away too leaving the sound a little less rich to my ears. Also, despite what most manufacturers publish, the frequency response curves for a particular speaker do change as the power is increased and what we expect is only available at the higher power end. There isn't only one curve which is constant and simply slides up and down the graph with the driving power. As your Bugera drops the power the frequency balance will inevitably change.
Now whether you can live with all of that, or even perhaps prefer it, you would have to try and see. There is something else you could consider trying and this is something I have used myself both at home and playing live. You could consider a fixed L-pad attenuator made from two high power resistors. If DIY stuff is not your forte then simply ignore the rest of this part. You can use those two resistors, one in series with the speaker and one in parallel, to drop the power into the speaker by any fixed amount you wish while keeping the impedance that the amp sees constant. For example, for an 8ohm speaker, adding a 4ohm (3.9ohm) resistor in series and an 8ohm (8.2ohm) in parallel then reduces the power into the speaker to 1/4 of what it would normally be while the amp still sees 8ohm. I made up a few versions of this for live work and I find it does work without the problems of the PS1 that I described as they are fixed soldered units without the weak link of wiper contacts. It could be worth thinking about.
One other thing you could definitely try is to use the emulated output of your GM40D with the Power Soak set on Silent. The amp is driving the internal soak while that signal from the output transformer is used as the input to a speaker emulation block which should make it sound a lot more "real and live". Run that signal into any flat music amp not another guitar amp, just as is done for front of house monitoring and see how it sounds. You should be able to turn that signal down without losing too much tone and feel. Even a simple hifi or a headphone amp setup can be quite useful in that way. I have to admit that this is not something I have ever done myself and been able to hear. When on stage I can only hear my amp next to me of course but engineers seem to think this works for H&K amps.
Finally this is really simple. The late great Stevie Ray Vaughan used to run his own amp onstage with an army blanket or two draped over it. That was to address this same problem. It took out a lot of the sting and lowered the volume while still allowing the amp to drive the speaker hard. It might be as simple as that for yourself and it is simple to try it and see. If it works for you get back and let us know as it would be good to have someone else's take on this.
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