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Everything posted by Phil Starr
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Good news story in the end, we all make mistakes, if you put them right then you are a company I want to deal with. I read this through because I'd recommended Hercules stands to a band member just a couple of days ago. I wonder if Fiat will send me a new car if I complain about their soft touch car handles disintegrating on my 15 year old Multipla?
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Stevie’s 12” FRFR Cab Build Thread (Basschat Cab v3)
Phil Starr replied to funkle's topic in Amps and Cabs
I don't think there is a problem, the only bit that would touch would be the outside of the cone. That is nearer the fixed outside edge of the grille so a 10mm distortion of the grille in the centre might only be 3mm near the edge of the cone, that would be quite a big dent! My only worry was that someone reading Pete's account might think it a good idea to rest the grill directly upon the speaker mount. -
Stevie’s 12” FRFR Cab Build Thread (Basschat Cab v3)
Phil Starr replied to funkle's topic in Amps and Cabs
I don't think you'll have a problem, Stevie will have specified the batten's you used to support the grille to keep it well clear I think they were 20mm that you used? The 17mm is the point where the voice coil comes right out of the magnetic field and I doubt you will reach that point in practice. the distortion wouldn't be very nice either. All I was worried about was that someone reading this would think the foam on the speaker was there as some sort of protection. It isn't. Folks, you need the grille well clear of the speaker. 15mm is probably minimum for a bass speaker and that doesn't allow for any bending or denting of the grille over time. -
Stevie’s 12” FRFR Cab Build Thread (Basschat Cab v3)
Phil Starr replied to funkle's topic in Amps and Cabs
I think you'll find the foam is only 5mm or so thick, less than the movement of the cone Xmax is 7mm and Xdamage 17mm I think. -
I think only you can judge this. One of my bands is a noisy acoustic band and I use floor monitors for us. There are three reasons to use IEM's in my opinion, roughly in order of importance: they protect your hearing you can hear everything better so you play better it keeps all the backline out of vocal mics and cleans up your sound Obviously if you volume levels are so low that your hearing isn't under stress and you can hear everything anyway then I personally would not worry about monitoring. The glory of acoustic music is that you can hear everything and you have the ability to organically work together, over-complicate things and you could lose something. We are just loud enough to need to hear the vocals through monitoring, most venues it is overkill but a few have tricky acoustics hence we take monitors. It also helps because we mix from on stage and we now hear what the audience hear. We also leave the backline at home and just use monitors. If you do go for in ears then you'll need everything miked up, If everything is already going through it's own feed to the PA that won't be a problem but if IEM's are working properly they block off outside sounds so all you hear is what you put in. The only way round that with IEM's would be to use an ambient mic, a dedicated mic positioned to pick up the sound the audience hear which should of course be a balanced sound. That can work well and if you feed it back to the desk you can mix it in with other things (vocals?) and give people their own monitor mix. It's all common sense really. Pretty obvious that if you don't have a mic on the fiddle player and then you put in noise blocking in-ears you won't hear the fiddle. Only you can judge if you can all hear enough so it doesn't limit your performance or what you would lose by longer hearing that acoustic sound.
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Stevie’s 12” FRFR Cab Build Thread (Basschat Cab v3)
Phil Starr replied to funkle's topic in Amps and Cabs
Well done all the people who contributed to this project. I'm sure there is plenty more to come when funkle has gigged the cab and we get more impressions of how it is working in practice, plus of course more impressions once the rest of the kits get built. My hope is that this design will go on to be a classic self build classic like the Greenboy designs. I know a lot of basschatters have contributed to the design and development, I applaud them all. This has been a truly cooperative project but of course one person deserves particular thanks. Well done Stevie -
Stevie’s 12” FRFR Cab Build Thread (Basschat Cab v3)
Phil Starr replied to funkle's topic in Amps and Cabs
Sorry I've just re read your first post, the t-nut is still in the cab. I've had this happen a few times, For anyone following this t-nuts always have a tendency to come out like this, even a fleck of paint on the nut or the screw will bind the thread slightly and the temptation is to press down on the Allen key or screwdriver to get more purchase and as soon as you press downwards the nut comes away. You should be able to re-engage the points of the nut with the wood by pulling the nut upwards back into the wood. try lifting the speaker or remove the horn and push your fingers in to lift it from underneath, it looks like it is close to the horn cutout fortunately. If you can get the nut to grip a little then unscrew the bolt carefully with no downward pressure which will push the t-nut back out. Even if you can only push the nut up a bit it might let you grab the head of the bolt and pull from above but be careful about that speaker cone. If you get the bolt out then you can remove the speaker. If the threads are undamaged so you can turn the bolt and nut by finger then re fixing the t-nut is simple. Get a big washer and put it on the bolt, thread it though the offending hole and put the t-nut on the bottom, without the speaker anywhere near. Tighten the bolt as tight as you can and it will pull the t-nut hard into the hole and it should be more secure. When you go back to fixing the speaker tighten all the bolts by hand first pulling gently upwards as you go so as not to dislodge the t-nuts. If you want to be doubly sure use the washer and bolt trick to pull all the t-nuts home before having another go with the speaker. -
Stevie’s 12” FRFR Cab Build Thread (Basschat Cab v3)
Phil Starr replied to funkle's topic in Amps and Cabs
OK t-nut in hand. Do you have a right angled mending plate to hand https://www.screwfix.com/p/corner-braces-zinc-plated-64-x-64-x-16-5mm-10-pack/15790 You should be able to place the t-nut over the corner so that at least two of the pointed spurs grip sideways against the bracket and you can press the flat top of the T down onto the right angle. That should make it stable enough to unscrew the bolt. -
Stevie’s 12” FRFR Cab Build Thread (Basschat Cab v3)
Phil Starr replied to funkle's topic in Amps and Cabs
A Mole grip is a name for a self locking plier. Like Hoover for vacuum cleaners. Gripping the T-nut is your priority, an allen key can exert a lot of force, way more than what you needed to displace the T-nut. You need to grip the round bit where the bolt goes in ideally, The pointed spurs that grip the wood will bend with any force. If you have a vice that will work well, you can tighten it slowly and get tons of pressure on the t-nut. Once it is secure you shouldn't have much trouble getting the bolt out, you may have spoiled the threads though. Just a minute..... -
Looks like a good choice. There's no doubt in my mind that the way to go is to get the noise level down on stage and put as much as you can through the PA. All that noise going through the vocal mics just means you can never get a really clean sound from the band. why carry fridges around when the PA's are so much better than 20 years ago. With a 23 year break you must be in your 40's at least and you'll need to protect your hearing also. Having said that we aren't there yet. The sound levels from drums aren't easily done away with and there are a lot of technically illiterate band members who think they can only sound good with their amps up full. Not every band has a top PA and there are a lot of people on mixing desks who don't really get it. The Fender or something like it will do just about everything you want. Onstage monitoring, driving the band from back line with vocals only PA and it has DI out for the PA. I've learned not to go on without backline, I've had too many gigs where soundchecks have been fine and you go on and someone has lost the settings and you have no bass through the monitors. If I've got an amp with me I can turn it off if the monitoring is good or turn it up if something goes wrong. If you've got something like the Rumble you can cover any situation, loud enough to keep up with the drummer, DI for the well engineered PA and a volume control for everything in between. Everything else is down to taste.
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TBH it's a bit much to expect a 2x10 to sound like a 4x10 with a tweeter as I am sure you know. I've never heard the cab in question so I'm making no guarantees about how a home build will sound. 400W is easy, most 10's will handle 200W+ and most decent speakers will outperform the old Celestions. If you are going to use them without a tweeter then you'd probably want a bit of an upper mid peak to make them sound a bit brighter. All the usual caveats apply; you won't know what they sound like until you build them and you won't get much back if you decide to sell them on. 60l is pretty big for a 2x10, it might be worth thinking this through and building a cab to match the speakers you buy and end up with an even more portable cab. Just saying Do you have a budget in mind? for just under £100 you could buy a couple of Beyma 10CM V2's which would probably suit your cab let me know and I'll model them for you if you decide you really want to build something yourself
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A bit but not much.
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Different valves have different voltage and current limits and are also limited in the power they can dissipate. The 6L6 is designed for high power amps and is a 30W valve The EL84 was the predominating valve in domestic audio with a 5W dissipation but can be pushed to 8W in certain circuits. To get more power you also need bigger power supplies and bigger output transformers etc etc. Heat dissipation is important and bigger valves can dissipate heat more quickly, the connecting pins need to be bigger to handle the extra current. The biggest valve I've seen in audio amps is the KT88 each of these can give 50w in the right circuit. To make high powered valve amps it's normal to use multiple valve circuits to get the power you want.
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Here you are, there are loads of things to read but this shows the basics of using a cheapo meter with REW https://www.roomeqwizard.com/REWhelp.pdf
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To be honest they are a cumbersome tool when RTA is so widely available on all sorts of gear. I've a very basic model and the readings are consistent given that the biggest problem is external noises. The frequency response is also limited so accuracy at the frequency extremes is compromised. Mine came with a calibration curve of sorts but not specific to my actual meter. I used to make measurements with 1/3 octave filtered noise and it was useful if laborious. It might be worth looking at some freeware like REW https://www.roomeqwizard.com/ you can start off using the mic and pre in the meter and then move on to a proper calibrated mic as the need and cash arises
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That's a great question, I'll see if I can give a non-technical answer. A speaker is a fairly simple system, you have a cone to move the air, the cone is on a couple of springs that hold it in place and you have a motor that moves it backwards and forwards. That is made a little more complex by the air in the cab and the nature of the cab itself. The motor is the coil moving in the magnet, the stronger the magnet and the more coil in the magnet field the stronger the force moving the cone. The heavier the cone and the stronger the suspension the less the cone will move for the same force. The same is true of trying to move a large mass of air, the more air you shift the greater the force needed. Because the speaker has a weight (the cone and air) balanced on the spring of the air and speaker's suspension it has a resonant frequency. Below that frequency it won't work well and you'll get a lot less bass. Just like a bass string a bigger mass and a loose suspension means a lower frequency. So for bass you need a large diameter of cone a long voice coil and a heavy cone. A big heavy cone is harder to move and a long voice coil means only part of the coil is working within the magnet gap at any one time so it's hard to make a super efficient bass speaker. Guitar speakers will have smaller thinner cones mostly and short voice coils so generally they will be more efficient/sensitive. The only thing the speaker manufacturer can really do to increase efficiency without other costs is to increase the power of the motor, with a stronger magnet. A shorter coil will reduce bass handling and a lighter cone raise the resonant frequency as well as making the cone a bit floppy Big magnets are expensive and really big ones mean reinforcing the speaker frame. Neo magnets being intrinsically lighter have allowed us to move the envelope of performance. At any one time there is usually a point where bang for your buck dictates which is the most economically sensible solution, it used to be lots of cheap 10's. Now we are at the point where single neo 12's and 15's make more sense but that is a mixture of cost, practicality and sound. Hope that helps
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Thanks Bill that's all true, I was trying to go for simple and not one of my long ones so I left the box related low end out and I think you are spot on. It was just a nice clear plot which showed everything I wanted.
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Stevie’s 12” FRFR Cab Build Thread (Basschat Cab v3)
Phil Starr replied to funkle's topic in Amps and Cabs
Good move, I'm still gigging the original Mk 1's in their half finished state, one day I'll put a proper grille on. -
Stevie’s 12” FRFR Cab Build Thread (Basschat Cab v3)
Phil Starr replied to funkle's topic in Amps and Cabs
As Jim says it's really easy stuff to work with as it stays workable for quite a decent time. If you don't like the texture you can brush if flat and redo it until you are happy. I use either a light pile roller which gives a kind of linen effect or an ordinary foam roller which gives a light stipple. I ordered the recommended open rollers from Blue Aran and they do give a great texture akin to the commercial cabs finish, which they get by spraying in all probability. I just prefer the 'linen' effect which I build up in layers. One flat coat and then usually four textured layers. Well done at getting this far, I'd have the speakers in as soon as they arrived so well done also for showing some restraint -
Basically it's very simple. Sensitivity is about how much sound you get per watt. 1 watt at 1metre is the usual measurement. Of course your amp adds more power and makes more decibels. moving from 1W to 100W adds 20 decibels so if your speaker gives 96dB per watt at I metre it will give 116decibels at 1m with 100W. Theoretically all you need to know is the sensitivity of the speaker and the power of the amp and you'll know how loud your system will go. If you understand it then it's also useful as a myth buster. I've seen 12" PA speakers saying they are 97db/W and can make 128dB, but that is nonsense. To get that extra 31dB would take over 1000W and a 12" driver can't handle 1000W I'm less pessimistic than most commentators so far about sensitivity figures. Of course it depends upon the frequencies you use for the measurement but it's a measurement that is easily checked and made at low signal levels. Most speaker manufacturers also provide frequency plots too so it's easy enough to check what they've done. If you look at the plot above the red line is the speakers response on axis it is pretty flat from 100hz up to 1000Hz. above that two things happen; the response off axis starts to roll off (blue line) and the cone stops moving as a piston and starts to flex in this case giving a bit of a dip and then a midrange peak. That's all pretty typical. I'd say this speaker is 100dB/W but you could argue there are more bumps above the 100 line than below and call it 101 dB. If you used this as a bass speaker then that mid bump would also make it sound louder. That all tells me that if the speaker handles 200W then it will go to 123dB at 1m and experience tells me that's enough to keep up with pretty much any drummer in most venues. So sensitivity is a useful figure when combined with other data, it is susceptible to distortion by advertising but no more so than other figures and a lot less in practice than figures for power handling or output.
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You usually get a euro cable in the box but a lot of suppliers throw in a UK cable separately. They are so cheap it isn't worth the labour of removing the two pin cable. Just cut the end off and wire in a three pin UK plug. the amp is only 700Wrms so a 5A fuse will be plenty.
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Brilliant. Lemonrock used to have a forum where at least everyone was a performing musician and of course there was Performing Musician which was absorbed into Sound on Sound now it's a bit of a desert. Love the Idea.
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Hi Tim, I'll have a go. First the phrase 'all other things being equal' is one used regularly by scientists when explaining technical issues. The whole basis of science is about controlling variables in experiments so that only one thing is varied at a time and any measured differences must be down to that change alone. Of course we know that other variables happen, but to understand what is going on we have to isolate them and deal with them one at a time. In this case the simplest thing is to try one two and four identical speakers with small signal levels (so nothing overloads and the speaker coil stays inside the magnet). I've demonstrated this to people and once built a special cab to do the demonstration. Putting two cabs in parallel you'd expect an extra 3dB as they will each draw the same power from the amp (in this case doubling the power into 4ohms) but you measure 6dB extra. That sounds like magic, a perpetual motion machine etc but the explanation is simple. When the cone moves it doesn't turn all that energy into sound, in fact most of the energy is dissipated as heat and speakers typically operate at single digit efficiencies. Doubling the cone area gives you 3dB worth of extra efficiency. (all other things being equal ) In this case very roughly two 10's have a similar area to a 15, so a fairer comparison would be between a 4x10 and a 2x15 which should have similar efficiencies. If they don't then you know all other things aren't equal and you can ask the question; why not?
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More love for the HA3500 here. best sound I've ever had and the tone controls are a dream. Still have mine but it's years since I used it in anger. It is a bit noisy and the times between cleaning up the pots get more frequent with age so I tend to go for my MB Tube which is also smaller and lighter. Mine broke once so I had a reason to have a good look inside. Some of the power supply caps in the early ones like mine have long leads which stand them off from the boards so they stress the boards over time and cause issues with the soldered joints. The cause of my problems and a bunch of problems at the time for others too. I stopped hearing of the problems in later models so I assume they fixed it. All it needed was a bit more care in manufacture or a blob of silicone to stop the caps wobbling.
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In your price bracket I don't think you can really beat RCF at the moment. I did a back to back comparison of many of the main contenders a couple of years ago and the RCF's were just much better at rendering vocals. I think they just seem to have handled the crossover points better and that often sits in crucial parts of the vocals. Our band have QSC 12's and they are as good (maybe the top end is a little harsh) but more expensive. I think Alec's recommendation of the ART 732's is spot on but have a look at the 735's too they are quite light and the little extra bass might help the keys at times and give you the option of adding a bit more kick and bass if you did need it. FWIW as you aren't looking at monitors at the moment I use RCF ART310's as floor monitors and they are spot on, the improved clarity and well behaved response give us quite a few more dB's before feedback as well as a very competent PA at smaller gigs. I've heard the FBT's sounding very good live recently, just haven't had a chance to A/B them. I'm underwhelmed by the Yamaha's personally (good quality speakers but just lack that detail in the vocals and the bass is just a shade woolly for me) JBL's sound a bit 'disco' to me which is hard to dial out but there is such good value out there at the moment it's hard to go completely wrong Hopefully EBSFreak will be along soon who's knowledge is more up to date than mine.