Phil Starr

Yeah big call out for Gear4Music. they let me know they aren't expecting any TC Elf stocks in soon. I cancelled the order and they dealt with that promptly. After all the problems with DV247 I'll definitely be looking to G4M in future.

Hi @RhythmJunkyWelcome to BassChat

Ok good question I'll give the answer in two parts. The volume of the cab is very important as it has frequency dependant elements and non-frequency dependant effects. It acts as a mass on the back of the cone, a spring and a sponge and that is in any speaker cab. In a ported there is the added complication as it acts as part of a tuned couplet with the port. The conventional theory on speaker design changes all these things into resistive, capacitative and indictive elements and crunches all the elements of the cab and the driver to balance them all out into a workable cab. The volume and the tuning of the cab have all been calculated to match the speakers we use and then we've built and tried them to make sure they meet the specs we started out to achieve. The shape of this volume matters far less than the volume and tuning, the differences caused by shape will be less noticeable and some will be below our ability to detect them. The real issue with changing the shape of the cab are resonances. It's quite possible for a resonating panel to put out as much sound as the speaker and you can both hear and measure resonances. There are also resonances in the air of the cab and in the port itself. The frequency of the resonances are set by the dimensions of the panels, their flexibility and their masses. If you are sticking to plywood as in all our designs then it's only the dimensions of the panels that are changing so you'll be shifting the resonances upwards with smaller dimensions and down with longer ones. The worst thing you can do is to repeat dimensions so panels all resonate at the same time. The worst shape is a cube and the ideal is one which sticks to the golden ratio (roughly 1.6:1) The advantage of using a ready made design like ours is that a lot of this work is done for you. In the later designs cab resonances have been looked at and bracing suggested where needed. The joy of a self build however is that you can personalise your build and let's face it there are only a limited number of options open to you if everything is to fit in. You'd probably have to be very unlucky to hit a truly awful resonance and so long as you know to look you can always find the resonances with your fingertips and knowing about them gives you the chance to deal with them by bracing the panel concerned.

I think it is a question of a design choice. You can design a flat response speaker and then use eq/modelling to get the sound you want and that is how the Mk3 was designed. Or you can decide to 'voice' the speaker to make a satisfying sound 'out of the box'. Different people prefer different approaches. I don't think it's about right or wrong, for me it is abut what works. It isn't really about efficiency or wasting power. the blue line (higher tuning) shows an extra 2db at 100Hz and the red and extra 2db at 40Hz, so which is louder? They are both the same sensitivity for the majority of their response. I designed the MK1 to give a satisfying result for a first time builder and gigged it extensively to check that it worked in a band situation. The secondary aim of these threads is to de-mystify cab design, there are lots of these little tweaks in commercial designs where the compromises are made for you. When it comes to something simple like this where blocking a couple of ports lets you hear the difference at home and decide for yourself then it's a perfectly sensible thing to ask and try out. @Gottastopbuyinggear might well decide the decisions I took all those years ago weren't right for his needs today.

Bugera Veyron? Meets your spec except for price. It's only 800W not 2,000 but it is 800W

Hi John, I wonder whether this belongs in an amplifier thread. In many ways this looks like another amp like the Gnome/BAM/Elf, if so it's a remarkably cheap option but it's roughly the same size and power output. As it happens I'm sitting here looking at a little power amp board based on the TDA8954 which will give this sort of power given the right voltage, it cost £10.35, I bought a preamp at the same time for £6.54 of course it needs a power supply and a case but it isn't hard to see how cheaply switch mode stuff can be built. Last year I repaired a Behringer active monitor with a replacement plate amp. That cost me less than £100 and that had two amps in it, nominally 250W for bass and 50w for the tweeter and that included most of a case and the power supply. I suppose I'm saying it can be done and if you get Thomann's three year warranty why not try it? I'll be mainly running my Gnome of a B1 too.

Yes i remember gigging with the prototypes, they could be overwhelming My drummer at the time once repeatedly asked me to turn it up, so I did, at the end of the first set he said 'I couldn't hear my effing snare drum' covering one port won't be enough to make a real difference try going down to two. This is what it will do to frequency response The trouble is that it also affects power handling and potentially port noise. this is power handling. 180W @70Hz isn't too bad but you need to know

Some of you will have noticed that I am (very slowly) trying to archive the BC designs so that people can go on building them. What has become apparent is that many of the parts have become unavailable though substitutes are always coming through as well. I'm going to tweak the designs as I go and one of the things I will do is move to only using standard building pipes as ports as the pre formed ones only seem to have short runs. The horns too have short lives it seems. I'll double check but I think the Mk1 was very slightly bigger than the Mk2/3, Both nominally 50l but I allowed slightly more 'extra' space in the Mk1 to allow for extra intrusions into the cab. So long as you use the Mk1 ports in the Mk 1 cab and Mk2 ports with Mk2 cab it won't be an issue. The shape was a result of requests that the cab should take an old heavy iron 19" amp with no overhang. My intention is to do an 'easy build' version of Stevie's mk3 shape cab as a revision for the Mk1 and that will go up eventually. In the meantime you can build the Mk3 shaped cab without a horn if you want. Retrofitting a horn has always been an option though you'll need a new baffle as I didn't leave enough space for the specified horn in the Mk1. The horn/crossover for the Celestion 1445 version of the Mk2 is still up on the thread and that was my favourite combination. Stevie is our crossover expert but I don't think changing the cab will make a significant difference at the crossover point but changing the horn or compression driver will as he pays a lot of attention to anomalies here and is very careful about the matching of horn and driver . @Gottastopbuyinggear I'm not sure why you would want to build a Mk1 with a higher tuning? Stevie and I differed over the preferred tuning and it is possible to come up with a series of tunings that will work well each achieving different compromises. There's a lot of discussion about it in the original thread I believe. The effects are complex and affect power handling, excursion and the shape of the response well away from the tuning frequency. We did listening tests too before we settled on the recommended tuning. There's lots of good reasons for tweaking the tuning but it certainly isn't as simple as taking out a bit of bass by tuning higher. Let me know what you are trying to achieve and we can see what the options are, you might be better off reducing the size of the cab for example. There's a lot of psychoacoustics involved too, just adding the horn will make your cab sound less bass heavy.

This is possibly the bit to look at first. The way to keep the vocals 'pristine' is to keep the level of bass reaching the vocal mics to an absolute minimum. What you want is for the audience to hear both the bas and the vocals and everything else clearly in exactly the right amounts. That's not about keeping it out of the PA it's about getting nice clean signals to the PA. The perfect solution for vocals is no backline at all, no sound bouncing around the stage and being picked up jumbled by the vocal mics. Ideally use in-ears but next best thing use your wedge monitors for bass. If you have to have a bass amp on stage use it for your own monitoring and keep it as low as possible. As to the new speaker without technical details we can't really tell you what sized cab sealed or otherwise would work well. Can you get the TS parameters for the speaker?

The marginal cost of a combi that would keep us all happy isn't that great but Neutrik would want their cut I guess and £10 on a £120 amp is significant. You'd think that Trace would want to distance themselves from their much cheaper competitors though.

A combi socket would be nice. I grew up on jacks and really don't mind using them on something that is relatively low powered, You can also buy jack to Speakon adaptors and I have one in the gig bag I my Gnome is in so I can use a jack/jack lead and still connect to a more conventional cab. I don't find it a problem. I've screwed my amp back together so can't help you with advice but most sockets are wired to the boards directly making a socket swap problematic. Is this an aesthetic thing for you or a worry about current handling?

So there's the sort of generic resemblance you'd expect. The switch mode power supply at the bottom looks very similar indeed apart from the heat sink. I quite like the toroidal transformer in the BAM but the component layout looks just about identical. The power amp is very similar too, lots of detailed differences but the same architecture but that's as you'd expect. You can clearly see the two amplifier chips bolted to the finned heatsink in the Gnome and sure enough there they are again in the Bam bolted to the big bent heatsink there. They may indeed be using the same chip, I'm not so keen on that inductor on the BAM which is there for rf suppression on the output (the untidy copper winding about one third down just right of centre) it's much tidier and more substantial in the Gnome. I wouldn't say they were built in the same place though, just the same chips in very similar configurations.

OK I can't resist. Eight screws later. The internal anatomy of a Gnome.

The input impedance is 10Mohm so, yes it's MOSFET but that isn't really a special feature nowadays. Also not in the advertising is that there is apparently some compression built into the input stage. It's mentioned briefly in the manual that came with it and there is a bit of crunch that comes in when the signal lamp starts flashing, I've no idea how Music Tribe (Behringer/TC) work but I doubt they share components with Warwick. More likely they share the same chip set produced by a third party. The big chip manufacturers release all sorts of application notes with circuits in, including board layouts and development packs. Certainly for the power amps manufacturers use mostly what they are given. The pre amps may vary but if you squeeze gain,bass,middle, treble and master controls into the smallest possible space you are going to end up with things that look very similar even if slightly different frequencies are used in thee controls. Behringer have also been known to um... make 'tribute' amps. If I open mine up I'll take some photos if someone wants to take a BAM apart. I doubt they will sound much different as they are pretty much flat response amps.

That won't be a dead cut off frequency, probably a -3db point (or sometimes manufacturers use a -6 or -10db point). The roll off is anything between 12-24db/octave. Sealed cabs roll off more slowly usually but there will generally be less bass anyway with a sealed cab. The designer can manipulate that a little, I forced the -3db point to 70Hz with my micro cab at the expense of a slightly faster roll off. It's much more complex than a single variable but one trade of you can make is making the cone lighter trading efficiency for a higher roll off point. you won't get rolling thunder out of a cab if f3 is 90Hz but most of the information is in the frequencies above 80 hz so it will still be useful. Placing it on a hard floor and against the wall or even in a corner will help add some of the bass back in.

Yes that's pretty much it Al. Limited but fool proof which is what I was looking for. And yes you can have six phones all doing their own mixes or you can do it for the technophobes if they need it. The reality is that once they have their mix you just save it. The best bit for me is the software, the simple menu structure and the sheer reliability/ease of use of the sliders. One tap on the screen gives you 1db adjustment and as most of your adjustments are of that order it's hard to completely mess up the mix or your playing. It's actually easier than physical sliders in practice, which was my only worry about going digital. You can trial the software for both by just downloading for free and it was trying that which convinced me the M18 is just more sorted for live work. If I was a sound engineer mixing someone else FOH I'd probably have gone for the Behringer but I'm a bassist standing at the back. having said that any of these mixers offer you so much more processing power than you'll have ever had on stage before. To be accurate the Behringer does offer multi track recording but the M18 doesn't, just the stereo mix. If I do decide to record our live performances multitrack I'll probably go and buy the X18. In the meantime the M18 does all I need and if I sell it I'll make most of the cost back I can see a place for both or maybe an M18 for pub gigs and an X32 for posh. The M18 though is the perfect engineering solution for my needs with 4 or 5 piece bands playing mainly pub gigs

I'd say the chances of complete success are fairly low. The speaker has to match the cab to get the best out of it. The cab is, or should be, matched to the speaker in volume and tuning. Then the speaker also has to be matched to the horn unit and the amplifier and the crossover. The chance of this all slotting into place by luck is fairly low to zero. The other issue is cost, as original the Headrush has value which you'll halve if you try and sell it messed with, even if you think you've improved it. A good quality lightweight 12 could cost you £130+. Sell the headrush and add those together and you could probably buy something better than you have. I'm all in favour of people experimenting as you'll learn lots but it's probably not the project to tackle.

Just a quick update, I finally got to use the prototype in anger this weekend. A noisy open mic with around 50 people in the pub. I've done a quick review over in the Warwick Gnome Thread as that's the amp I used with it. I didn't know it was happening but the host was posting on FB so this is a snippet recording on an iPhone House Jam Cab Everything set flat with a bit of compression/overdrive on the input and maybe 2-3db left on the output Warwick Gnome into this single 6" 8ohm speaker. It's not hi fi but a decent set of headphones should give you an idea of the volume you can achieve with this tiny cab

If anything happens to the speaker the cab is still a good potential home for quite a few 15's out there with only a bit of tweaking o the port length. Still it's great to know you have a working Scorpion.

Yes it's just the micro cab, 1x6. you can just about make it out at the back of the stage area. The cab was built as a bit of a proof of concept. I frequently roll off the bass when I'm playing depending upon the venue and what else is going on in the mix. It's pretty obvious that most of what we hear as bass is the second harmonic 80-160 Hz so I wondered what a speaker with a flat response to 80Hz but very little below that would sound like. I also wanted something really portable and not too intrusive to play when I meet up with an old university friend. I had the Fane kicking around waiting to become a midrange driver and when @Pea Turghasked for a 6" to fit in a practice amp I did some modelling in WinISD and built my own too. Three or four bassists have tried it now and the response has been great. (should that be the response to the response?) I'd taken the Lockdown 110T to the pub too but didn't need it, I'd hoped to swap it in but the place was really busy and we only played three songs.

A bit of an update, I've been using the amp for a couple of days in rehearsal with a single 6" cab, surely the ultimate bijou pairing. I wanted the Gnome for just this sort of thing. We have a duo with amplified acoustic guitar and two vocals and I needed something super compact to carry with all our luggage or a weekend away which would produce a satisfying sound for rehearsal. Which it does in spades. Within 5 mins the amp was quite warm and fair enough to get the volume through a small speaker it was working about 3-4x harder than with a 'normal' bass cab. the funny thing was that as we turned up it stayed at a similar temperature and even between songs it seemed to stabilise at 'quite warm' not quite q hot water bottle more like the forehead of somebody with a bit of a fever, so maybe 40C. The tone controls are OK the bass control seems to shelve so bass is enhanced without getting extreme boost at the bottom end, the mid frequency is lower than my Peavey or MB so it really enriched the bass without getting harsh. The treble is not particularly dramatic, I mean it works but you don't get searing treble and with this speaker moderate roll off wasn't making a huge difference, but this speaker is only flat up to 6kHz so maybe it is acting mainly above this frequency. I liked the mid control though. The best sound I've had so far is with my Zoom Hartke emulation and a touch of compression and bass boost, it pretty much sounds like it does through headphones. the Gnome works well with flat controls and something else doing the eq/processing So tonight I took it all to an open mic in Reading, the Butler if you know Reading. everything else through the provided PA but bass through the Gnome and 1x6. Maybe 50 people in the pub and it was a lively night with an enthusiastic and noisy audience. The pub is an awkward space with an L shaped bar area. I needn't have worried the Gnome and mini speaker were more than adequate My duo partner says the bass dominated the on-stage sound and and Nicole running the sound said it was about right out front. The amp was up quite high and the compression light was flickering but I reckon there were a few more db if I wanted them. I you remember that this was with a tiny 6" speaker then with a couple of decent 12's I think the Gnome would cope fine with a shed building drummer. Finally if you are in Reading on a Friday go and check out the Butler's open mic. The standard was insane for an open mic, some of the singing was exceptional, there were at least six singers I'd have loved to gig with. the audience were enthusiastic too, it was a great evening. Aha looks like the host recorded us, this was with everything set flat with a tiny touch of the top trimmed with the tone on the j bass https://fb.watch/8P3Y8FUcuU/ apologies for the audience singing

Thanks @agedhorse I've never been in a position to specify a speaker. and it's frustrating sometimes to see the compromises manufacturers of drive units settle for. I'd understood 'soft parts'as being essentially the cone and dust cap plus the surround and suspension. The Faital PR300 is a good example, the stock unit looks to be very untidy under break up, the peak in the 320 much easier to deal with in crossover design and I would guess more acceptable for most of us as a sole driver. I'm kind of assuming these are some of the issues you were able to address and wondered how you approached the issues? Just curiosity really, I've reached an age where I don't think anyone is ever going to offer me the chance to specify the speaker I want.

A lot depends upon how you are using your speaker. If you can separate the on stage monitoring from the audience sound by going through the PA then this opens up all sorts of options. Does your drummer rely on your bass cab for his bass monitoring? If your bass cab can be relieved of all other duties then there are lots of solutions. Kickback cab behind you, wedge in front, smaller less directional cab or in-ears. All of these will improve your band's sound as well as improving your ability to hear what you are doing. If not then you only have limited options. A cab with a decent horn crossed over well down into the mids is going to be less directional. Raise your cab to ear level by buying a second cab or use something to tilt your cab so it points at your ears. The other issue is eq. to pick out the details in your playing you need to hear the midrange essentially, boosting the mids is going to help a lot, but if your cab is what the audience hear then that probably isn't an option. I'm guessing here that you choose15'sand 4x10's because you like to shape your sound with your cabs?