Phil Starr

It's an interesting thought, as cabs get smaller the need for folded ports increases. I've tended to avoid them so far but this is a relatively pain free way of getting a result. Thanks

Just to be clear, the cheap QTX driver is the same one used in a lot of cheap cabs, mainly those advertised as 'party cabs' or disco cabs but also used as cheap and cheerful PA systems in churches and schools. Maplin used to sell them as their cheap as chips speakers. They are remarkably good for the money but I just wouldn't advise anyone to go out and buy one, they really aren't up to any serious bass use at any high power level, They might sound great for home practice, I couldn't say but for £135 you could probably buy an active PA speaker with amp tweeter and crossover built in but with the same driver. He's probably designed the cab for the Beta anyway. That's what I'd do and the cab will probably be tuned to around 50Hz. A 50l 50hz cab with a Beta will be fine and he's probably used winISD anyway. Here you go https://www.ebay.co.uk/itm/QTX-QX12A-12-ACTIVE-PA-SPEAKER-400W-DJ-DISCO-SOUND-SYSTEM-PA/202077424069?hash=item2f0cc0c9c5:g:O2YAAOSwls5Y63zR Bill will know better than me of who uses the Beta in their commercial cabs, they might be a similar price to these and they'd definitely be cheaper used. Nobody is ripping anyone off but there isn't a free lunch being offered either. There's a TC RS212 in the for sale section for £380, less than a pair of the Eminence driven cabs at £200ea, They'd probably be similar but I'd go for the brand name because I'm not bothered about stuff being new.

I'm amazed this thread is still running. This is a bass player trying to make a little money by building cabs. He's chosen the simplest of designs, a roughly 50l 1x12 and is offering effectively to put in the driver of your choice at different price points. You'll get exactly what you pay for. His advertising claims are no more silly than anyone else's, kind of true but not very enlightening. I'd suspect you'll get a very simple box which you could build yourself for £40 but someone else has put it together for you. That QTX driver is the sort of driver found in millions of cheap speakers with a hundred different brand names all coming out of a factory somewhere in China. It'll make a noise but won't have a lot of deep bass and will give up the ghost fairly early if you turn the power up due to over excursion. The Eminence Beta will sound like an Eminence Beta, it's a good mid range driver for bass and is used re-badged in a number of designs. An unbraced 3/4" ply cab that size isn't going to be high end but the panels are rigid enough not to be awful and you can always add braces yourself. I'm not as cynical as others, having done something similar back in the early 1970's. It's tough when you have no capital and you have to do everything yourself. You operate on the tightest of margins and keeping costs down by saving on handles and fittings and sticking to one design makes sense. I doubt he's making minimum wage once his time is factored in but we all start somewhere.

Well done for keeping going. It's always distracting when things like that go wrong but you can only control your own bit and getting on with that is the truly pro attitude, whatever gets said afterwards. Good to hear the Mk 1's got some approval too.

I've no quarrel with using the ports as handles. Ports do have their own resonances and putting them on the sides or backs means those resonances will be less audible, though whether that is a significant factor I doubt. It's quite a clever idea I suppose and it's rare to see anything novel, I haven't seen this before. The piezo tweeter is one of those cheap things that a lot of people switch out of their bass cabs, neither here nor there really, some people like them as giving a little more top. Basically this is someone trying to start a business building cabs and it's a pretty straightforward 12" cab fitted with an Eminence driver, the cheap one fitted with the Alpha isn't going to sound too great but the one with the Beta, well it's a nice driver at that price point and fitted to a lot of commercial cabs. You could buy a lot of used 112's for that but who knows you might have the next Barefaced

If it works then it is worth more than that, the only fly in the ointment might be if the transformers are bust, the output transformers are costly items to replace and that would detract considerably from their value. Mr Foxen who used to post here frequently but has gone quiet might be someone to contact as he did a lot of work on old valve amps. Everything else on these amps can be replaced fairly simply.

Bill is absolutely right, cabs on top of each other with the centres of the cones aligned is best. Anything else and you'll get places on stage where frequencies are cancelled due to the sound arriving from the two speakers at different times. However I'm not a purist about this. We rarely play in ideal conditions in the UK, lot's of small venues and misshaped buildings, and bands who are run on a shoestring budget with inadequate gear. Sometimes you have to improvise and then it is a question of balancing two evils. When I started doing PA a long time ago we often used to swap speakers in a stack so the bassist had one of the guitarists 4x12's in their stack and vice versa. On a wide stage that helped them hear each other. Some of the older rock bands still do this, probably out of habit but at least one band had that arrangement at Glastonbury this year. If the onstage gear is just for monitoring and what the audience hear is through a massive PA it wouldn't be a problem. In one difficult venue I had my amp facing the audience but added my practice amp (Hartke Kickback) as a monitor for the drummer. If you think about it some bands scrap backline altogether and use floor monitors, the bass might be coming out of all of them so you have set up all sorts of interference/cancellation problems. It works because you are much closer to your own monitor than the rest. That means it is louder than the rest so although there is interference from the other monitors in practice it isn't noticeable. So I'd say default position is vertically aligned cabs but if you are due on in 5 mins and someone really can't hear then be prepared to be creative, then go back and think how you can sort your monitoring after the gig. In our case we gave the drummer their own monitor at ear level and let them mix in what they wanted to hear, mainly vocals and bass.

Without wanting to start a major derail of this thread there are a lot of assertions here that are at least debatable. One thing however stick out as just being wrong, that rectangular vents give more "woof" and ducts are more hi-fi. Whilst the shape of the ports will change the port resonances and changing that shape will also alter the point at which turbulence sets in the idea that different shaped ports of the same length and cross sectional area will have vastly different sounds isn't something with any evidence or mathematical proof that I've seen. I'm interested in what you mean by Line Array. The first of what we currently consider line array systems appeared in PA systems in the 1990's. A series of identical cabs with the mid and high frequency drivers vertically aligned to control dispersion. The idea of 'line source' has been around a lot longer, single cabs with vertically aligned drivers. The original paper on that was published in the 1950's but the phenomenon was known a long time before that and I remember churches with line source speakers fitted probably back before WW2 plus designs published in old books before Olsen's paper. I can't think of anyone using Line Array for bass, though the Genzler Bass Array cabs look interesting.

Yes it's an old Sheffield unit and there were various versions rated 150W and 250W, there's also a recone kit advertised which is 8 ohm. There's a moderately lively second hand market for Peavey drivers so you could probably pick up a cheap replacement if something went wrong. Frankly you've not got a lot to lose, you could probably get away with using your Elf for quite a while with no problems. If you are going to use it at home it'll make a lot of noise. If you are going out and gigging with a loud rock band then it's probably not going to last too long and you'll want a better speaker fairly quickly anyway. Matching amps and speakers isn't an exact science anyway. Play your 150w amp with clean tones and you're probably only averaging less than 10w anyway so it isn't going to overheat the speaker. Play with distortion and a lot of bass boost and you can probably blow quite a few speakers rated well above the amplifier power by over excursion at the lowest frequencies

Yep there are arguments for and against putting the port on the back. The main argument for is that ports produce noises at mid frequencies due to all sorts of resonances, putting them round the back means the noises can't really be heard. Against is the thought that you can't ram the cab hard against a wall and potentially block the port, but even a few cm away it won't be a problem. With compact cabs it's always a bit of a problem fitting everything on the baffle without weakening the panel. The other solution might be a slot port, you'd have to form it in timber so there is extra woodwork but it's a nice tidy way of creating a port, another more complex method is that used by some manufacturers of building triangular corner ports like Mesa

Seriously no problem. If there's any basis at all in this sort of thing then it's nothing to do with damping. It's more to do with power and the technology of the time. 120w is a big valve amp both in terms of cost and weight to carry around. Nobody was going to carry around an 800W valve amp! Back in the day there was often little PA support for the bassist so big venues had to be filled by the bassists amp. The answer to that was lots of efficient speakers built into a cab and the 8x10 was the best solution of the day. They were packed in a sealed cab which gave them a big boost in the bass and the cheap drivers also had a natural peak in the mids that helped punch through without sounding harsh. The Ampeg fridge was born and there were lots of 'me too' copies. Most of the cabs were sealed just because everyone had to offer a competitive product. just as everyone is offering a lightweight 12" now. So what you need is an efficient speaker. That Barefaced claims 102db sensitivity, though it doesn't specify whether that is at 1W or at 2.83volts. (2.83V is 1W into 8ohms but 2W into 4ohms and it's a 4 ohm speaker) Anyway 100W into a 102dB speaker is going to give you 122dB which is going to match a drummer pretty well and because it's a valve amp you can run it closer to the rated output without the distortion becoming objectionable so you'll probably be able to get an extra 3-6db if you need it. You could eq in an Ampeg sound if you wanted or just worry about eq'ing the sound you like best.

Not with a name like Browning

I'm no expert in musical instruments (I'd take Andyjr's advice over mine) but I do a lot of working with wood including restoring antique furniture. This sort of clouding doesn't look to me like anything T-Cut would benefit and I agree from the photos it looks like something is in the finish. To me it doesn't look like a lacquered finish from the photos, but I'm far from sure. It's very similar to my dining room table which is 15 layers of Danish oil which is a mixture of oils and alkyd resins. If it is it's not an impermeable finish and does tend to soak up thins over time like oil from our skin and even sweat. It may well be that over time people have added finishes, like a layer of wax or maybe oil over the original finish. That sort of bloom can also be caused if someone has used a silicone based polish at some stage. I'm guessing here without the bass in front of me but people do all sorts of strange things to wood. Personally I'd live with it and maybe just sort out the dinks and scratches. If you do want to try something yourself I'd start off by cleaning off as much of the patina as a solvent could take off. Work on bits that won't be obvious with the usual solvents and a cotton bud to start. Alcohol is probably the mildest or even just soapy water if you keep it as dry as possible. White spirit or even petrol are a bit stronger but go carefully on a small patch, there are also commercial varnish cleaners (not strippers) available. go carefully, good luck

I must admit as a scientist I was originally sceptical about some of the claims made during basschat debates about tone, and it is true that in many areas there is a general lack of data from properly controlled experiments. In particular I found it hard to believe that the amount of energy transmitted from a string would move a relatively massive bass body enough to feed back to the string and modify the original signal. I own four basses, a Fender P American Deluxe, a Highway One J, a Burny T'bird and my starter bass a Cort Action Bass. The only other bass I've owned was a Gibson T'bird. The J,P and Cort all have J style necks, all with maple/rosewood necks and all the basses are 34" scale. The Burny is a pretty faithful copy of the Gibson, certainly in physical shape and pickup placement. They are all currently strung with Dean Markley Blue Steels The Cort has had a series of pup replacements, it plays great but sounds completely dead, both acoustically and through the pups. All of the others sing acoustically, sustain better than the Cort and the acoustic sound is reflected in the sound I get through an amp or through headphones. The two T'birds sound fairly similar acoustically, both have remarkable sustain too but the Gibson had a lovely rough edge to it which the Burny lacks, I have that down to the pickups in all probability. Now you are right that strings, pup's and their placement all make a difference but pups aren't going to make much of a difference to the acoustic sound. The bodies of the two Fenders vibrate enough for me to be able to feel them through my stomach never mind my fingers and lets face it, if basses didn't vibrate clip on tuners wouldn't work. So I'd say it is certainly plausible that the nature of the body would affect the sound and that some energy is transmitted to the strings. I'm not hazarding a guess as to how important each factor is but I certainly no longer believe a bass body or neck is an inert part of the system.

I must admit to being tempted by the One 10 for just this sort of use. Of course I'd rather design and build my own being me but I just can't find a suitable 10" driver to deliver the sound I'm after. Did you read the simple 12" build thread I put up recently? The one where I stuffed the original Basschat Mk1 into a 30l cab. If you get time to do a quick build I'd be interested in what someone who has lived with the Mk1 for a while thought of the smaller and more coloured cab. It's nowhere near the small size of the One 10 but if you wanted to experiment...…….

Nancyraygun are you still in the room? Anyway, here's the thing all other things being equal the efficiency of loudspeakers is proportional to their surface area, doubling the cone area gives the equivalent of doubling the amplifier power. There is nothing magic about modern speakers just a gradual improvement in materials and engineering which enable you to squeeze a little more sound out of a modern drive unit. The state of play at the moment IMO is that you can just about squeeze enough sound out of a single 12" cone to match a drummer, so long as you aren't demanding anything unusual in terms of boosting the bass. The Barefaced designs along with loads of others takes advantage of this and the ultralight cab helps a lot with portability too. If you are still reading this thread then I'd recommend you think in terms of buying a couple of 8 ohm, 1x12 cabs. a single one will do for rehearsals and small gigs and adding a second cab will double the efficiency and increase the power from your amp giving you a real boost in sound. It means a single journey for smaller gigs and a return trip for big gigs, though I do sometimes manage two light'ish 1x12's, amp and bass as one lift if the route from the car is straightforward. I think you should be fussed by tone though, compared to speakers amps add very little tone of their own and changing your speakers will change your tone more than changing your amp. I'd go out and try as many speakers as possible, preferably with your own amp.

You could mount the port in the rear of the cab, that way you could fit the bigger port in. .

Yes that's right I assumed 40l, speaker ports and any bracing

Couldn't resist it I've modelled your cab tuned to 55Hz and compared to my 30l cab It will give you just over 2dB more bass from 100hz down to 40hz (fundamental of bottom E). That extra box volume will give you noticeably more bass in other words, at the cost of a little power handling but power handling is still good, there's a dip to 300W at 90Hz and it handles 180w at bottom E which is pretty good, way better than the Eminence you started looking at. In practice you don't get a lot of fundamental from the pickups so unless you start using stupid power and an octaver you won't have problems at all in any normal use. There's still a bit of extra 'punch' at 120Hz but it's not a bad frequency response at all. Use one port of 110mm (plastic waste pipe) 15.5cm long or two 64mm (guttering downpipe) vents at 11.2 cm long. (or 3 at 19.2cm) You'll get a little wind noise at full power but you probably won't notice it in practice.

The best thing you can do is to download Winisd. It does all the calculations for you and will calculate the best sized box to give you the deepest, flattest response the speaker can cope with. Then you can change the box size and see on the graphs what that does to the frequency response, It'll calculate the port sizes too and everything else you can imagine about the low frequency performance too and you'll learn loads about speaker design in the process. You'll have to put the technical specs of your speaker in manually though, once you've done that the rest is easy. If that is too much for you one of us will calculate a suitable port size for you, probably using winisd.

Good Luck with this, I'm sure you'll get plenty of help from people here.

Because they are looking for simple answers. It's undoubtedly true that some of the difference in what we hear comes from the skill of the bassist. It is equally true that lot's of other factors are important, like the diameter of the speaker cone or the size of the cab. Sometimes those differences are significant, sometimes trivial. Few of us have the time or inclination to calculate all the factors in so as a species we grasp for simple answers and quick decisions. If they have a heavy old 4x10 they will swap it for a lightweight neo loaded 12 and if they don't like it conclude it's all down to being neo and then eliminate neo from their purchasing calculations from then on. I cringe when I see interviewers asking politicians "well minister is it ***********, yes or no." Their viewers may want simple answers but running the health service or education is rarely anything like as simple as speaker design. It's lazy reporting and ultimately people end up voting for politicians that offer simple answers like Trump, Putin or dare one say Hitler. Beware anyone who says it's all down to any one thing. Whether they say 'speaker cone size makes no difference to tone' or 'all 15's have a sound and all 10's a different one' they will be wrong. Sweeping generalisations are rarely correct. Neo magnets weight for weight are stronger, that much is true. It let's you do different things if you are building a drive unit but it can also let you do the same things if you choose.

well done

I'm doing this remembering repairing kit back in the very early 70's, well 1970 actually. My memory may be a bit iffy at that distance. Compression is something valve amps do naturally partly down to the valves themselves but also due to the saturation of the output transformer. Basically they just peter out as the output rises giving a nice soft sounding distortion as they over loaded. Guitarists used this to create all the sounds of early rock music. Combined with the feedback you get at ridiculously high levels it also gave them a lot of sustain to play with. Everyone forgets that most of these amps were pretty unreliable and a band running four valve amps on stage plus often valve PA amps was experiencing a lot of technical failures. Plus back problems from carrying the amps. Having 20 KT88's on stage was a nightmare to be honest. Transistor amps were coming in by then WEM (not much more reliable) and later HH for PA followed by early guitar and bass versions. They were certainly cheaper and quickly became more reliable but transistor amps really distort unpleasantly when overloaded so we looked for a way of getting that gentle overload that the old amps gave. Compression was what was needed so compression on instrument amps started as an effect to give 'valve sound' The first compressors I encountered used ordinary car bulbs to compress the sound. At high power they get hot and their resistance goes up, put the signal through a bulb pick it up with a photocell and bingo, compression. The next stage was a voltage controlled amplifier. Take the output and use it to control the volume or gain of the amp and you get compression. These were often adapted from tape recorder automatic volume circuits and used FET's as the controlling element. By about 1974 integrated circuits took over thousands of components in a single package. You could get undistorted compression at will but you wouldn't do that complexity with valves. So you wouldn't simulate valve sound with valves for obvious reasons. They still make optical compressors as an effect but with VCA's you can get completely controllable compression which is largely done digitally nowadays anyway. Valve based computer anyone? If anyone is interested https://www.soundonsound.com/sound-advice/q-what-optical-compression

Yeah that lead will put the two cabs in series which is important as it keeps your amp safe. you'll get some extra efficiency by using two speakers but cancelled a loss of power into 8ohms. Assuming the speakers are identical you get double the power handling using that lead and excursion of the cones is reduced so your bass may be less distorted and the speakers are safer. If you use that lead with two 8ohm speakers you'll end up with the amp seeing a 16 ohm load so less power. What you could do is use that combination as an 8ohm speaker and then add in an extra 8ohm speaker in parallel through your amp's second speaker outlet. That'd give you full power from the amp, buckets of power handling and high efficiency. No guarantees on what it would sound like but worth a try?