Phil Starr

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.

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.

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

A bit but not much.

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.

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

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

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

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.

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.

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.

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.

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.

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?

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.

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.

I'm quite rusty on electronics and I don't know what value those capacitors are but C1 and C2 just look like DC decoupling to me, They may well be rolling of the bass, C2 at least which is nice as it means you can boost bass by 3db without over excursion of the speakers low down below the port frequency. I'd have to go back and look at the whole circuit but I'll guess Trace designed a decent roll off in to make the most of those watts. It's a nice feature of old single ended power supplies. It's possible the values chosen will affect response but yeah it is a 'proper' gain control rather than just allowing you to overload the next stage. In the end you have to trust your ears. The Alpha's have poor damping of the one movement, the old Celestions may not have been much better as they tended to be under damped too. Is the cab sealed? in any case the underdamped cone will jump around at relatively high bass frequencies and roll off early so you'll have plenty of warmth but little deep bass, I quite like that sound playing live. Sorry I didn't offer to help on your other thread, which I followed with interest

This is what matters: "I can't see myself needing anything louder" pre shape and boosting the bass will make it louder, but you do it because it's the sound you want. 4x10's are louder, all other things being equal, than 1x15's. The input gain doesn't matter a fig, you can have a 1W amp with lots of gain or a 1,000,000W amp with low gain. Gain and power aren't linked. I kind of love the blank incomprehension of these threads. A watt is a watt, there's nothing magic about TE watts or any old watts v's new watts but lot's of technical reasons why people might think one amp is louder than another. For people with a love of Trace amps nothing else will do, they are just sharing the love with others who share their passion. For techies a watt is a watt so long as it's measured properly. We worry about people making poor purchases based on mythology or advertising hype. We can run on for more than four pages about all this In the end though this isn't about MMR vaccination or using homeopathic medicine to cure cancer, it's about people getting pleasure from a sound they love. We should cherish those who love vintage as much as those who want to help by sharing expertise. It's all good fun over a coffee break spent on Basschat. Oh, well done for getting your combo back on the road Stub

I have to say I love playing this. It's both a nice one to relax to and just enjoy the ride, and the audience reaction but it also has places you can put a bit extra in if you fancy it. There seem to be dozens of versions over the years with a gradual change from a very pronounced shuffle towards four to the floor. It also seems to show up most of the guitarists I've played with who can never seem to remember the repeats of the opening riff when they recur or how to end the song As for changing keys. I do not for the life of me understand why singers don't demand it more often. They can't all have the same natural range as the original singer, surely they ought to sing it in the key where they sound best. It seems to be more about the crossover points in their voices, between head and chest voices and so on. If the dramatic part of the song or some fast articulation occurs when their voice is weakest a semitone or tone can really beef up the song. So many singers can't seem to 'hear' the song in anything but the original key. It's all compromise of course; I'd struggle with All Right Now if I didn't have an open string to play in the octave jump and I'm usually happy when the guitarist asks to play E rather than Eb in a few songs. In the end though if the singer is straining for a note or pitchy the whole band sound crap so why wouldn't you play to suit the voice they have?

It's probably worth going over the whole driver and the cab itself. If it's an old speaker sometimes the dust cone in the middle or even the corrugated surround start to come loose as the glue hardens and breaks over time. anything loose in the cab will sound and anything not screwed down properly or even the speaker grille might be making a noise.

The power an amp can drive is roughly halved if you double the resistance. If you connect two 8 ohm speakers in parallel they will act like one 4 ohm speaker with each getting half the power. So yes your amp will give 300w into 4 ohms You say home practice so is it worth the cost for a little extra volume you probably don't need?

I feel like a spoilsport but the AH 200 is 200W into 8 ohms and the MB is 300W into 8ohms. That sounds like a lot but is actually only 1,76dB noticeable but only a marginal increase. Loudness is mainly about the mids, any mid suckout and an amp will be noticeably quieter and a mid boost will make it sound louder. We also know nothing about the gain structure, the Trace may just have more gain. What is interesting is that we probably all get pretty pleased when an amp delivers more than we expect and pee'ed off when they under-deliver. I'd rather have Trace's reputation for loud watts than make outlandish claims of high power that can only be delivered under very limited circumstances, which is now the new normal. I use an MB Tube, it's loud enough. I can go louder than the drummer, previously I had a HA3500 and before that a Peavey MkIV, they all went more than loud enough, I'll bet the Trace is more than enough too. I borrowed one of the Trace 15" combo's and it was loud enough but more importantly it sounded great. Sounding great seems more important than who has the biggest watt.

People are being far too pessimistic. The RCF is a good quality PA speaker designed to have as flat a response as they could get. It will use the same drivers as the powered version and peole have had good results with RCF speakers. The point about your bass amp not being flat is valid. Room problems apply the same to any speaker and by 'flat' we simply mean it tracks the output from the bass pickups, whatever that is. you are talking about small gigs so output below 59Hz is usually little more than a nuisance to be filtered out. the only other issue is whether the speakers can handle bass without damage, that shouldn't be an issue with a 15" RCF driver, PA drivers are designed to have similar heat dispersion to bass speakers and the bass only driver is likely to have better excursion than a bass instrument speaker if there is indeed any difference. The advantage of an active speaker is that the matching of amp to speaker is done for you and it is easy to build in protection for the speaker. There are plenty of old PA cabs around, borrow one and see if you like the sound. The RCF is probably going to be an upgrade on most PA speakers but just check you like the cleaned up sound before you spend any money. It won't be exactly like the RCF but it's better than just a leap into the dark.