Chienmortbb

[quote name='Roland Rock' timestamp='1438429482' post='2834462'] Real world you say? I have a 1000w Type A power amp which easily handles the lows. Then I sell it, and with half of that money buy a cheaper Type B 3000w power amp which handles those lows just as well. Great. My inner voice will be nagging me to buy the 3000w version of the Type A power amp, as it will be amazing. I'm now skint with an aching back, but happy. [/quote] So as a Class A amplifier is around 10% efficient, you need 10000 watts or around 40 Amps of current at 230V. Three times what you can draw fro a single socket ( unless you are running three phase) it is August not April isn't it!

So what do you consider a super tweeter. I am not asking for a particular technology rather what the frequency response of a good tweeter is. Also is there an argument for a Low Pass Filter before a tweeter? I wi be honest, putting a tweeter in a bass cabinet that extends to way over 20KHz seems crazy to me even fior slapping. So any ideas on what the top -3dB point should be for a tweeter? I have no real opinions myself, just trying to learn from other people.

How much extra bracing will the slot port give. Will it make room on the baffle for more bracing?

Dood said "[color=#282828][font=helvetica, arial, sans-serif]Engaging the bright switch and setting the passive tone stack to that classic scoop setting (all controls pointing up) tamed the cabinet. A little bit of excess cone movement - but I think the Kilo has absolutely no subsonic filtering. "[/font][/color] [color=#282828][font=helvetica, arial, sans-serif]Do you think that and HPF should be fitted to al amps? The amp I am buiding has an adjustable one and the more learn about speakers, the more I am convinced they are vital.[/font][/color]

The midpeak on the SM212 is less pronounced than either of the Kappalite 12" speakers. I wonder why is it so obvoius here? I can understndthat the 3012LF may be cossed over at 1-2KHz meaning the peak is missed or at least tamed. However the 3012HO peak is much closer to 1Khz and that has been used in a number of commercial cabs. I understand that mids reflect off the rear of the cabinet and come through the cone but does that also mean that they bounce back through forward facing ports? I am sure I read that Audio Kinesis put their ports on the back because of this but I may be remembering incorrectly. If so that is correct, might there be some reduction with a slot port? Dood, can you compare this to any commercial cab you have reviewed or used?

I hAve finally completed fitting and soldering the Pre Amp PCB and the High Pass Fillter & Parametric Equaliser PCB. They are pictured now in place on the chassis.

Mods, perhaps you could combine tis thread and the one entitled [b] Class D amps lack uumph?[/b]

[quote name='Grangur' timestamp='1437394755' post='2825552'] So am I reading this right; it seems they don't fail on you when in use, you arrive at the practice studio and you find them not working? I recommend you start taking your amp home. YOU might not abuse it, but others may not be so careful. Is someone connecting a lower impedance cab than is recommended? Or some other problem? Fact: electronic devices don't fail when not in use, unless it's water or heat damage, and you'd see signs of that. [/quote]you are correct, most failures happen upon switch on when the most electrical stress is on the amp.

[quote name='Truckstop' timestamp='1437284050' post='2824781'] The way I've always thought of it as, is that Class D 'sounds' loud while class A 'is' loud. [/quote]Class A is not used an any real amplifier over about 10 watts. You probably mean Class A/B.

Sure to some the idea of the sound or response changing if the cabinet is rotated is ridiculous but allegedly many silly things change the sound of a cabinet. To me it appears that there will be very little change but if the driver is closer to the floor then there will be a change, albeit quite small. The question is clearly prompted by the idea that tall is better than wide for bass drivers, when used in multiples. On a final note, having read many forums/ threads on speakers, there are more daft answers than daft questions.

[quote name='Phil Starr' timestamp='1436972739' post='2822477'] Stevie's right. (I keep saying that) we started out talking about offering either a Celestion or the Eminence Beta 12A-2 as a cheap option with the Beyma as midprice and maybe the 3012HO as the deluxe version. Modelling showed the extra for the Beyma was worth the money and the 3012 was offering almost nothing for a lot extra. Which made life simpler for us. [/quote]When I first saw you were using the SM212 I was a little surprised but when I modelled it I could see why you chose it. When you take the price into the equation (well in Europe anyway) it is clearly the best driver for the project. It is about 1.4Kg (about 3 lbs in old money) heavier than the eminence speaker and handles slightly less power but the sensitivity in the low and low mids area is very similar and is hardly a dealbreaker.

The Thumpinator is a High Pass Filter. That mean low cut so it us cutting the very low stuff that you can't hear but can hurt your speakers. SFX do not publish their specs but I suspect it is around the 25-35Hz region. This is where most modern bass reflex cabinets lose control of the speaker come, allowing it to move a long way with very little power applied. This really low area adds nothing to your sound and cutting it helps your amp too as you are not asking it to power sound you don't want. The filters in amps are often too high and do cut the sounds you want. I have heard that some amps cut from 75Hz and that is too high to just take the speaker. However the new thinking is to combine a fixed HPF for speaker control won't a variable one that can adjust for room boominess. Look on TB for FDeck's HPF thead for more info. Going back to the original thought about the thumpinator, it will give real benefits even if you cannot hear them!

[quote name='Passinwind' timestamp='1436882283' post='2821661'] Nice job. Are you using a pot for setting final stage gain where R24 would go? And I also agonize a lot more about front panels than the back ones. [/quote] You spotted the deliberate mistake.Actually I cannot find that value at the moment so I am going through my stash to find it. I was not planning to have a pot but now you mention it it could be a good idea. One issue though is that using a pot cups put the gain close to 1. ( or -1 as th opamp is inverting) the plan is to use LM4562 as the output opamp and this works well at unity gain. Other similar opamp a such as NE5532 becomes unstable at unity gain so a pot would probably need a series resistor to ensure stable operation if other opamps are to be used. Having said that I think I have just talked myself out of using anything but the LM4562.

Now I would appreciate some suggestions. The system is very flexible. I can choose to switch various circuits in or out. So the questions I am going over are: 1. Should I have the HPF switchable? Pasdinwind dies but after using his amp for some months he leaves it on all the time. 2. Effects return can be configured as series or parallel. Most Amps are currently series but parallel allows some local control over the wet/dry signal mix. Oh and should those the switch and EFX return level control be on the front or back? 3. The Parametric EQ section gives me control of the mids from about 100Hz to. 2000Hz and of course this overlaps the fixed middle control. It is worth adding a switch to change the fixed mid frequency? It makes the amp more flexible but more complex. 4. Active/Passive switching and gain change. Passinwind has only active basses while I have currently only passive ones. At least one of my bases will be converted to active in the next few months with a variation of the two band MM preamp but I want to have the ability to have the two options. So two Jack sockets or one Jack plus an Active/Passive switch? I would appreciate any comments based on experience.

Ironically the omissions make for a more satisfying build. I am studying the circuit diagram/schematic more closely than I would if documentation were 100% and learning more as I go. The Pre amp board is now complete apart from the wiring. Some of the components are now mounted off board as the preamp was designed before the HPF/PEQ circuit and taking components off board allows us to configure the circuits to the best arrangement. Below is the picture of the completed board. It still needs to be wired but I will leave that until the front panel is complete. As you can imagine I am taking more time and care over the front panel as it will be on show more than the back panel.

[quote name='Phil Starr' timestamp='1436867829' post='2821446'] More news, one of the cabs is to be reviewed by Dan Veall, bass reviewer of Interactive Guitar Magazine http://www.iguitarmag.com/reviews/?issue=&brand=&producttype=Bass and of course Dood of this parish. At the present the Cab is about to wing it's way to Dan, or it will be once UPS collect it. It'll be great to have a professional and independent opinion of the cab and I'd like to thank Dan for taking the time to do this. [/quote] Having seen some of Dan's reviewsI think this is great news. On another matter. Stevie is comparing the cab to his own 15/6 cabinet. Can you tell us more about that cab? Is it your own design or based on ages boy plan. What drivers? Size and weight? By the way I thought I knew a bit about speaker design but have learned how much I did not know during this process. Thanks for the hard work and patience with me and others.

[quote name='Phil Starr' timestamp='1436867829' post='2821446'] More news, one of the cabs is to be reviewed by Dan Veall, bass reviewer of Interactive Guitar Magazine http://www.iguitarmag.com/reviews/?issue=&brand=&producttype=Bass and of course Dood of this parish. At the present the Cab is about to wing it's way to Dan, or it will be once UPS collect it. It'll be great to have a professional and independent opinion of the cab and I'd like to thank Dan for taking the time to do this. [/quote] Having seen some of Dan's reviewsI think this is great news. On another matter. Stevie is comparing the cab to his own 15/6 cabinet. Can you tell us more about that cab? Is it your own design or based on ages boy plan. What drivers? Size and weight? By the way I thought I knew a bit about speaker design but have learned how much I did not know during this process. Thanks for the hard work and patience with me and others.

[quote name='stevie' timestamp='1436712482' post='2820116'] I didn't carry out a full-range measurement, I'm afraid, which would have shown up an imbalance between the bass and midrange. I did a ground plane LF measurement and a gated mid/high measurement but couldn't join them together because the first one was not calibrated. In any case, you need to factor in the changes in frequency response from the cabinet being on the floor, which makes a gated measurement problematical because it relies on filtering out all reflections. I've found that an RTA works well for checking the sound balance of a speaker in situ, but I didn't do one when I had the speakers here. I do know that my own 15" + 8" is ruler- flat on the RTA, which suits me, although others may well prefer a mid-foward balance. I can have a closer look at this when the speaker makes its way over here again. [/quote] No problem. I would prefer a flat response but I have enough control on my amp to EQ it flat if need be. Incidentally what sort of frequencies do you consider Mids? I tend to think 400-800Hz but I think many think mids start much lower.

[quote name='Thunderpaws' timestamp='1436705945' post='2820047'] This all sounds like great progress. I wonder if the natural mid bump will help me punch through more against three guitars with my Genz Streamliner. I am drink rely going to make one of these. Time to start ordering parts. Where's best to get the driver from? Lots of hardwork from you guys, well done. Cheers, Garry [/quote] Looks like you have the same spell checker as me Gary. You can get them from Blue Aran they are about £75 plus postage. I am not sure whether they could offer a group buy but maybe I'm comjunvtion with the UK Distributor of Beyms they could do a deal. I will leave that to The three musketeers though.

Stevie/Phil Did your measurements show pronounced mids or is this something that has just shown up in real life testing?

I have started to assemble the preamp board, the one shown in all the pictures to date was the Rev 1.0 PCB that is going into my combo rebuild later. The preamp has all the resistors and the IC sockets installed and I will be installing all the capacitors tomorrow. The capacitors are last because they are tallest. Although there are three IC sockets, each IC has 2 operational amplifiers. So six gain stages but as the ICs are audiophile quality, and because Charlie (passinwind) tweeks over and over again for the best performance/noise figures going. Passinwind has designed Valve preamps for at least one well known bassist and although the EQ borrows from that design, he uses this solid state design himself in both the integrated 500W amp and the small form factor 700W design pictured in an earlier post.

To make things worse some UK manufacturers make 10" speakers that are much larger than 255mm.

To think this used to be a pint sized thread😜

15s are not slower but In general will have a lower output at the top end compared to a 10 from the same range.

As Lord Claber is doing a guitar cab soon we may well see a change. However seeing Pete Townsend using a mass of Fender combos at Glastonbury makes me wonder what is between the ears of some guitarists.