Phil Starr

I'm not an expert on the maths around fluid dynamics. the only time I studied it was back in the 60's so this is really broad brush. The thing that causes compression and the wind noise is turbulence in the port at high velocities. Turbulence will add in an additional resistive element to the port reducing the radiation of the cab around the tuning frequency. The port only really radiates sound at the tuning frequency so isn't going to affect the frequency response apart from around the tuning range. I don't think anyone can reliably answer the question about 'allowing' for 100W. Without knowing exactly how you play and what eq you will use in the future it's almost impossible to say what level of discount you could reasonably apply and how frequently and by how much you'd exceed 15m/sec in the port. Remember too that these guideline port velocities are just that, guidelines. The people that developed the theories behind all this differ in what sort of port speed is acceptable and I've seen figures between 14 and 20 given as ideal. To give you a wattage figure we'd need some basis in theory to make a calculation and we don't have that. If you look at the port velocity at 50W you are looking at 3dB down, if it is 6dB down it is 25W. Port dimensions around the sizes you are thinking of seem fine to me and so does a 64 hz tuning.

Not quite, the point is actually really simple physics. The fundamental is the note produced when the string is vibrating as a whole. It's fixed at the bridge and nut (nodes) and the middle of the string is the bit that is moving furthest (antinode). The antinode for the fundamental on an open string is at the 12th fret and that is the only spot where you'll get full output of fundamental. The closer to the bridge you place the pickups the less fundamental you'll get. The note is irrelevant if your bass is 34" scale the fundamental dominates only 17" into the string at fret 12. if your PUP is at 4" from the bridge it isn't going to get much fundamental. https://www.physicsclassroom.com/class/waves/Lesson-4/Nodes-and-Anti-nodes You've found that on your bass it is 12dB down and this is typical, in fact what I predicted. That means at the point where your amp is turned up loud not much of the power is going to be in the lowest frequencies which will cause over excursion. If you are running at 100W into the speakers it's unlikely that 10 of those watts are going to be fundamental unless you are using a lot of bass boost. If you are my feeling is that the speakers are going to be overwhelmed before you get a noticeable level of chuffing from the ports. You've run WinISD, the plots you need to consider are the excursion plots and the maximum power plots which tell you whether the speakers are coping or not. That is a concern, but with little drivers like yours I wouldn't worry about chuffing. Experienced builders are telling you a single 68mm bit of pipe (outside diameter of course) is going to be enough and that is good advice IMO. I've got 12" drivers here with a pair of ports this size running at 300W at gigs and I've never noticed problems with port noises at gigs. i'm probably getting some problems with compression due to port resistance but again in practice I haven't noticed. Speaker design is like squeezing a balloon, you squeeze one problem and another pops up. You can't really achieve perfection don't let that be the enemy of building something good.

You are probably over-thinking this. What your amp will do is actually trace a complex waveform which tracks all the different harmonics added together. It will do this until it runs out of volts or sometimes the power supply in the amp will run out of current. If you are putting music in rather than a test signal then the notes decay over time and there will be gaps between the notes. Your amp will pump out its full power at all frequencies over its pass band if you put the right signal in. You are back to where you were in the other thread. Your bass pickups aren't in the middle of the strings so won't give you as much fundamental as harmonics, you'll find all your fundamentals are down about 12dB or 1/16th of the power compared to the 2nd harmonic unless you are fretting higher up the neck just as I said last time, your own measurements confirm this. The advice to keep wind speeds below 18m/s are from people designing for hi-fi use It's nice if you can achieve that but sometimes you can't in a practical cab especially if you are trying to build something really compact. In practice this is not going to be a problem.

If you are going to use a crossover at 180Hz then you won't be running into 4ohms. Below 180 you'll be running into the sub and above that into the One 10, both at 8 ohms. At the crossover point the impedance of the crossover in series with each speaker effectively makes them both 16ohms (sort of) and so the overall 8ohms is maintained all the way. No free watts I'm afraid What you will do is change the sound, hence Bill's suggestion you go for a second One 10. The One10 is designed to be 'old school' compensating for the lack of deep bass with a bit of bass boost baked in at around 100Hz, which i for one really like. If you colour in the missing frequencies it will change the balance of the speaker. You'll get more deep bass probably as you'd expect, you might find one of the speakers is more efficient than the other and will dominate. What you will get is the possibility of better power handling as the power is split between the speakers. with everything below 180Hz diverted away from the One 10's you could possibly double the amp power, or just trde that for the same amp with less distortion. If you have the woofer then the proof of the pudding is in the listening in this case, give it a try and if you like it try it more If you don't then save up for a second One 10

from the looks of this you don't have a balanced line mic. You would need three wires; two out of phase and ground. You can do this with the right transformer and it would do some impedance matching for you too but to me it looks like the original guy has a simple isolating transformer and his isn't balanced either. It's hard to tell from the link exactly what he has done. It doesn't really matter though, you've made a mic from a speaker and it works. You don't have a balanced line to run 25m cables back to a mixer but does that matter? It's fun doing this, I days gone by I've used a headphone as a mic, you just plug the jack into the mixer and speak into the cup. It sounds remarkably good and makes an OK drum mic if you aren't too fussy.

Out of curiosity I checked, the cab is made out of poplar ply which is probably the lightest practical material to build a cab with. It's actually quite expensive compared to generic hardwood ply. 15mm thickness is quite acceptable for a cab this size but 18 is normal. The reviews mention some stiffening inside but this may be a single batten across the back which is common in 4x10's. Even so this is remarkable and if you were home building buying this cab and replacing the drivers might be almost as cheap as building your own once the cost of covering and hardware are included. Here's the link https://www.thomann.de/gb/harley_benton_solidbass_410t.htm A cab like this is going to be filled with drivers with very modest magnets to save money. Retail it's hard to buy any 10 for under £30 but that's OK the original idea of an 8x10 was to get high volume and plenty of bass warmth by packing lots of cheap speakers into a cab. These speakers will only weigh 2-2.5kg with 1.5" voice coils and magnets that weigh around a kg. http://www.bluearan.co.uk/index.php?category=Speaker_Components&startprod=0&instockonly=&man_old=all&masthead=Loudspeaker_Drivers&subheadnew=10_Inch_Drivers&sort=pr&manufacturer=all&stock_option=All+Availability&submit=Go This cab really is serious value for money. I think Harley Benton is just a label and they can be made for Thomann by anyone. If it was Bugera then that is the same group (Music Group) as Behringer and many others and whatever way you cut it this is probably just a generic 'made in China' cab. Final observation, it might be around the weight of the BF but the BF cabinet is going to be a lot stiffer and have complex cabinetry as well as more powerful neo speakers inside.

That's interesting, I've found I'm leaving my J behind most of the time as I'm getting frustrated getting a good live sound with the J-Retro, which sounds great at home. Any thoughts as to why?

I was interested enough to read this thread and It's an interesting question. I've been thinking about it for a while. My go-to practice bass is my Cort action bass, I love the neck and it's my starter bass and owes me nothing so it's left lying around completely carelessly and nothing to worry about. The down side is that it has no real sustain and sounds completely dead. Over the years I've tried all sorts of strings and changed the PUP's (currently Kent Armstrongs) but it's just lifeless. I've two Fenders and a Japanese Thunderbird and they all sound so much better and they all have a lot of sustain as well as sounding so full of life but they stay in the rack until gig days arrive. Sustain is really demanding, you really have to worry about string damping and dynamics. Playing live in really loud environments makes it really lively as feedback creeps in and the strings start to run away from you but it also increases the fun factor. There's nothing like it when the bass comes alive in your hands and every fret touch becomes a hammer-on. So sustain is a really double edged sword. Hence the foam damping I guess. I've always assumed sustain is at least partly about resonance, the body of the bass vibrating in tune with some of the string movement. For me the sustain of the fundamental always seems there but the higher frequencies within the note seem to fade away quickly if the bass doesn't have sustain, so it's not just the volume but the timbre that changes over time. So I'd love to hear some opinions and maybe someone with a bit of knowledge to come along and maybe i can mod my old Cort and make it come alive.

bass cabs aren't really designed to do what PA subs do. You don't really need a lot of subsonic bass out of a bass cab, there's a limit to how mush bass a bass pickup puts out so the actual amount of deep bass is fairly low often they don't go much below 50Hz and frequently they can't handle full power over the next octave. They also have to cover the full range of a bass and this means a compromise in the lower frequencies. The speakers in a sub only have to cover a couple of octaves and nothing over 150Hz so they are specialist one trick ponies and they can do that well as a result. However if you have them and you lack bass from your PA you have nothing to lose by trying them, you'll need a crossover to limit the frequencies you send to them and probably to limit what goes to the tops. If you can borrow a crossover it will let you experiment and you can see if it works for you. It won't be perfect but if it is an improvement then why not? However there is another possible route. If you can send the kick and bass feed out through an aux channel on the mixer you could send them through your Schroeders freeing up the tops from having to deal with any deep bass. Aux fed subs are an accepted technique which might be worth a try. You can then filter everything else through the mixer at 80Hz, which you should be doing anyway.

Back in the day I had two of these which I used as amps for my mobile disco. I absolutely loved them at the time and clocked them at the time pushing out short term undistorted peaks at well over 120W on an oscilloscope. I had to replace the output transformer in one of mine and did the same job for someone else but this was way back in the early 70's. They'd certainly be loud enough but you'd need to pair them with something fairly efficient in the way of speakers, think in terms of a 4x10 or 2x15 unless you can afford something exotic and expensive. Might be worth messaging Oli Foxen who used to be a regular on BC. He was a real valve man and restored a lot of old valve amps including some of these old Sound City's. He's based in Bristol

I'm feeling lazy and I have to cook so there's a 'technical' explanation buried here https://www.ultimate-guitar.com/lessons/the_guide_to/making_it_loud.html enjoy

Celestion are using a more conservative method of rating Xmax than Eminence so direct comparisons aren't strictly valid. Eminence base theirs on 10% distortion so probably the Celestion would come out at around 5.5mm Xmax. That's a nice speaker at a good price and would be a bit of an upgrade on the BN10-200 which has a cone that starts to break up lower down than the 300X which may 'cure' the nasal sound, it may not go that much louder though. All the speakers you mention have a strong midrange rise in frequency response including the Barefaced that you like. Just dropping any old speaker in a cab can be problematic, sometimes it works fine but you can get problems with a poor response or reduction in power handling. I wonder if the advice to sell the cab on and put the money towards a second barefaced would be better. Having two identical cabs is going to give you more of what you want and mixing cabs is going to give you something else. It may be that like me you enjoy tweaking things and just generally experimenting with the cabs you have. I think that Celestion looks a bargain and would be a cheap option, if it doesn't work you could sell it on or build a cab from scratch optimised for the Celestion. Selling it on would probably get almost all of your money back.

If you are price sensitive i wonder why you are considering new? There's a Barefaced 210 in the ads here for £400 which is more than your budget but a lot of speaker for your money and other bargains to be had and that is just here. This person has a couple of TC cabs to sell, you'll need to read the ad but it looks like he may split the bundle if you take one of the cabs

I hadn't realised this was the dual concentric, I built a couple of cabs for the Monitor Golds based on the Westminster back in the day. Your's seem to be a pro PA version with a straight sided cone but the same motor system. Those cabs are tiny for a speaker of that configuration and the catalogues show the frequency response or 100-20,000Hz which is why you're getting no bass, They are clearly vocal and instrumental monitors where keeping bass out of the mics would be important. It also looks like they are collectors items so messing around with the cabs makes little sense as you'd be reducing their value. There are ads for these with $1,000 tags in the states. https://www.hilberink.nl/codehans/tannoy125.htm https://www.hilberink.nl/speaker.htm

Is it bad that I still like Prawn Cocktail Black Forest Gateau and Liebfraumilch? Is that like still wanting heft?

It has, I guess I'm one of the techy nerds here so I'll give you the bullet points. You can't trust the specs on promotional material Having said that there are no magic watts, class D watts are the same as class A/B watts. The PA you hear at most big gigs is almost certainly class D. Amps of all classes often cut corners on the power supply. That will mean they can only provide power downhill with the wind behind them. The tendency in the past was to design and test on sound. Amps and speakers were often highly coloured and most of us like that. Modern amps tend to be cleaner out of the box. So long as they have plenty of headroom you can usually eq something decent. Only buy an amp you've had a chance to play and listen to at volume, don't worry about the class, that's for the designer to sort and if they haven't, don't buy it. I've moved from an old Hartke 3500 which sounded great to am MB Tube which was okay and much more reliable but a bit meh until I dropped it off the stack and I bought a really cheap Peavey MIniMax as a temporary replacement. It's great, really solid sound out of the box. One all to each.

OK the caveat is that I know nothing about the Tannoy and this is all from basic principles. If it's a small sealed cab then it's probable that the low end is deliberately rolled off, it may have been designed for vocal monitoring mainly and the lower frequencies aren't needed and aren't present in the vocal range anyway. It would be normal to use a sharp 80Hz filter anyway so nothing below that. I guess if you are mixing then you need to hear the sound as the audience? In a band situation i'd be really happy with bass roll off as the bass from your mains is omni-directional and you get a lot of bass even behind. Have you tried these live yet or is it that they don't work at home? The mix of direct sound from these and bass from the FOH speakers might be workable??? Porting the cab might work but at the very least you need to tune it to a sensible frequency, just removing a handle won't cut it and could severely reduce power handling and hence reliability. If you can find the Thiele/Small parameters for the drivers someone could optimise the port dimensions for you. If not you'll have to go old school. it's relatively easy to find the resonant frequency of the speaker and you could tune the cab to that or just trust that the resonant frequency is around 50Hz which works OK most of the time and tune the cab to 50 Hz. We'd need to know the internal volume of the cab to calculate that for you. It would probably work but no guarantees.

So there was one of these part exchanged

You guys are good, much closer than my guess. anyway here is the receipt. That makes a rig like that about 7 weeks wages at the time. It would cost you less than two weeks wages now for something of similar quality. Somewhere between 1/3 and 1/4 of the price. Mind you in those days there were gigs

Well you are all doing better than I did. For what it's worth average weekly wage in June was £502, in 1979 it was £89.30.

A mate of mine is selling his old Peavey set up of a Mark III bass amp and 2x15. It's already sold and I have to say it still sounds great, lots and lots of trouser flapping heft The thing is he has the original receipt from 1979 and it just strikes me how much cheaper gear is now once you allow for inflation. So just for fun, how much was a Peavey 2x15 and 400W amp in 1979. I was way out, but no hints. This is the Mk IV but it gives the picture

Hi David, there's a lot in your response! I'll have a think and maybe reply in detail later. There's an online emulator somewhere where you can slide the position of the pickup and it shows the frequency response. Basically it confirms what we already know that you get more bassy as you move away from the bridge and bridge pickups are always more tinny and neck pups more bassy. If i find it I'll send it across to you. It's in one of the 12" design diaries in this forum. The 6-12dB figure was illustrative only. It'll be much more than 12 for a bottom B and a bridge PUP and much less for an E played on the G string. You could theoretically do the calculations for air velocity at all the frequencies for any particular PUP position but I don't think that would be useful. If you are getting wind noise form the ports your poor little 5" drivers are going to be in over excursion anyway. If you tune to 70Hz you aren't going to have any discernible output at 30Hz or even at bottom E (41Hz). Far better to do what you said and use a 50Hz filter, take out the subsonics that you won't hear anyway and use your speaker with confidence. Your smallest slot port is 3000mm2 Stevie's 50mm circular port is even smaller than that and is satisfactory. I think you can go ahead and build.

I think the answer is in your original question. You ask how the power is 'split' between the fundamental and the harmonics. The answer is that there isn't very much fundamental and it's likely to be 6-12dB down in terms of what comes out of the pickup and which note you are thinking of. The fundamental is greatest at the twelfth fret and much reduced at the position of the pickup. By wisely using a filter you are also reducing the chances of over excursion and chuffing in the ports. http://www.buildyourguitar.com/resources/lospennato/index.htm All this goes out of the window of course if you use 12dB of bass boost and an octave pedal! Any cab like this is going to be a compromise, you are using small speakers and want a compact cab so looking for full power with no port noises at all frequencies is something you are going to expect to compromise on. It's useful to know the points where you expect problems and port velocity is just one of them. Have a look at commercial 'briefcase' designs and see what compromises they have made. If your port dimensions are coming out close to theirs you are probably in a safe enough place with your design. I've looked at this for some of my own designs and you can come up with something where the port can end up with you needing to considerably increase the size of the cab. In the days before Win ISD I never calculated port velocity and some of my older cabs have quite restricted port dimensions. You can show the chuffing with a signal generator easily enough but I used them for years without noticing anything playing live..

I looked these up when the thread started. Looking on the Thomann site though the Bugera is cheaper and a known entity, there are also offerings from TC, Markbass (admittedly lower powered) and Laney at similar prices. There is a lot of good stuff to be had in this price bracket. I bought a Peavey Mini Max just before lockdown for just over £200. Not knocking Harley Benton but this is a competitive field.