Chris Hales

I couldn't agree more! In my opinion, specs are supposed to help us choose products that will suit our needs. Unfortunately they rarely fulfill that function and, more often than not, just confuse the issue! It should be possible to do better than what we're currently given spec-wise, but there are always intangibles and personal preferences to take into account, too! Even trying in a shop has its limitations. I bet there are loads of people here who have tried an amp out in a shop and been blown away by it, only to find it doesn't cut it in a gig situation...

That's really interesting and I suspect the different efficiencies of their speakers is an influencing factor too.

I've pretty much no experience with valve amps, but I think they'd often quote rated power at 10% (or sometimes, I think I've heard, 3%) the reason being that their THD is in excess of 0.1% even when they're not clipping. In the context of valve amps, the power rating has even less bearing on the actual volume - as the mighty AC30 attests!

I'd not call myself an expert, but I can offer a bit of insight here. There's not a lot of standardisation regarding how amplifier power is measured. Some spec sheets will state "at the onset of clipping", others will define it at 0.1% THD others at 1%. The fact of the matter is, once you're starting to clip the THD rises very quickly, so there's not much difference in the measured power whether it's quoted at 0.1% or 1% - certainly not enough to account for the discrepancy between 300W and 500W. Something that really confuses the issue is that volume controls are not calibrated, so you have no idea where clipping is. To make matters worse the control law of volume controls vary a lot, too. Even if the gain of two amplifiers is the same with their volume control maxed out, their gain at 50% might still be wildly different. (When I worked at HH, it was believed that our midlands based rival were "cheating" by using linear rather than logarithmic volume contols. At low volume settings these give much more gain than logarithmic controls and it's easy to mistake this for being louder or more powerful!) Then we have the sensitivity of speaker cabs which vary wildly and this can have a huge effect on the actual acoustic power that's being generated. Which is to say it's all very complicated and unless you can calibrate the gain of everything any subjective comparisons of "power" or "volume" are pretty meaningless. That's not to say anyone is wrong about whatever their favourite amp/cabinet is, just that any comparisons with another bit of kit in terms of volume may not be very valid. (In the Hi-Fi world it's generally reckoned that you need to gain match to within 0.1dB to make any valid sound quality comparisons. 0.1dB is the difference between 100W and 103W!) Hope this is of interest and maybe even help, too!

Nothing wrong with the TL072 - I've used it in many products. I would have considered it for this, but I wanted something that was a bit less current hungry so it could be phantom powered. The output of the pedal is AC coupled, but it takes a while for everything to settle after it's been powered up. A lot of that is due to the "artificial" mid point which is filtered heavily to keep noise out of it

It's a low power bipolar op-amp I'm using. I'd prefer to use a JFET op-amp but the input capacitance of very low noise parts tends to roll of the high frequencies. That's not really an issue seeing as it's intended for bass use, but I tend to be a bit obsessive about these things! You're right that the thing can't really make up its mind what it is! In part, that's deliberate in attempt to give it as wide appeal as possible. I was never really thinking of this as something you'd use all the time but rather somethng you'd be really glad you had in your gigbag once in a while. The popping is causd by the DC settling at first switch on. I'm also obsessive about preserving the low frequency response, so the time constants are all very long. I definitely could work on that and still be better than a typical FX pedal or bass amp, for that matter. It sounds like I have a bit more work to do and a bit of research into how a typical active DI behaves when it's first plugged in. Thanks for your really helpful feedback - I really appreciate you taking the trouble to pass on your thoughts. Cheers Chris

Thanks for your thoughts and comments. I know it's impossible for this thing to suit all users, but I am very consciously trying to give it wide appeal. The way I see it, if I was to do a small production run of these, there is no way I could compete price-wise. The bigger the production run, the more competitive it would be, though it's never going to be an inexpensive product. Don't get me wrong, I'm not looking to get rich from this but if I was to take it further, I would like to be fairly confident I'd at least cover my costs.

Thanks Jack! Seems like I'm sort of on the right track though I have to say my assumption was that most people would have no effects at all. I guess I'm out of touch with what is going on in the bass-playaing world these days! I've not really checked what's out there, but I would have thought all active DIs would power from a regular FX power supply. I guess I've got that wrong! Cheers Chris

One thing I'd chip in is that with a passive bass a passive DI is likely to affect how your tone and volume controls react. With everything full up the effect might be minimal, but probably not otherwise. I hope this isn't a stupid question, but if you're happy runing an (active) effects chain, why not an active DI as well?

Thanks so much for the useful and detailed feedback - plenty of food for thought there! One thing I hadn't considered is that people might be using the DI out and instrument level out at the same time. I think I'd have to add a transformer to the DI out for that to be guaranteed hum free. The shaping control currently affects all outputs, but i think you're suggesting it would be more useful affecting the DI output only. One of the challenges I had with this pedal was keeping the current consumption low enough that it could be phantom powered, but I think I could manage that without affecting anything. Good shout regarding the rotary controls. You used to be able to get pots with removable knobs, so I could probably used those to cover both bases (haha!). Would having the footswitch sticking out present a problem, though? I don't think I have the resource to engineer a slick Boss style footswitch to this thing! Going back to passive DIs, which seem to be everyone's preferred option, do you not find these affect the tone - if there are no preceeding effects pedals, anyway? One thing I feel is important is to present the instrument with a high impedance (my prototypes present about 660k, which is already lower than the 1M I'd usually aim for). A passive DI would present around a tenth of this, which I reckon is much too low for a passive instrument. Thanks again for your really constructive input Chis

Interested to know how you hook everything up? Is your bass straight in to the passive DI or do you have a pedalboard inbetween? I've been working on something for just this sort of situation and it woud be really helpful to understand how you link everything together and what lets you down. Cheers Chris

Hope I'm not hijacking this thread, but I'd be really interested to hear what you guys would need from a DI box? The reason I ask is that as well as being a mediocre bass player I'm a mediocre electronics designer and have come up with a "pedal" that gives you some degree of volume and tone control as well as being 9V/battery/phantom powered. I have a couple of these with gigging bass players but I'd be really intrested to hear if it's something people would find generally useful. I have nothing to sell, but I'd love feedback if it's something you potentially would find useful. I'll attach my "user manual" in case you're interested. Cheers! Chris Embarrassingly Direct.docx

I'd been wondering about Markbass Strings - I'd seen somewhere that some of their sets are especially designed to be smooth to the touch, but I've also read reviews saying they can quickly and suddenly go very dead! I've bought a set of Pure Blues so I'll string up my Jazz bass with those again and see how long they last. At least I know I'll enjoy them for a few months! Coincidentally, I dug out another bass that I'd strung up with D'Addario XLs (nickel wound) in February and they're still really bright so maybe that's the way I should go, even though I don't particularly like the feel of them! It's all so complicated, isn't it?!!

Yes, I did do that, so I'm pretty sure that's not the cause. Also, I've had similar experience with DDT strings which have a hex core (and I think are stainless steel) so if there is a difference it's probably in the make up of the string. I've noted that DR strings have more layers of thinner wrap wire, so maybe that's the difference? I'm not after a very bright sound and even with the Pure Blues I prefer them once they've settled in a bit. My gripe isn't so much the longevity per se but that when they do start to go dull, they go very dull very quickly. I have a couple of other basses strung up with D'Addario and Ernie Ball (both also nickel wound) so I'll see how they behave. How often do you guys change you strings? The Pure Blues have been on for about six months (probably an average of an hour of play each day) and are now really too dull to do anything useful. Cheers!

I've strung up a couple of basses with DR DDT and Pure Blues strings respectively and really like them for their soft feel and low finger noise. Unfortunately, what I also notice is that they seem to go very dead very quickly and very suddenly - much more so that, for example, D'Addarios which seem to stay bright forever. Is this just my imagination or has anyone else here noticed this, too? Can anyone recommend a string has the smoothness of a DR string but stays bright like a D'Addario? Cheers! Chris