Chienmortbb

OK the Superfly spec is officially 2 x 250W into 8 ohms. However the chips used in the Superfly are actually not good for 250W. They are bridged TDA 8927s and thet are good for about 180 watts each into 8 ohms. Ironically they don't give much more than 110W into 4 ohms so best keep the cabs to 8 ohms. I will look at the rest of the circuit later to see where you might get some gain back.

Phil, Do not beat yourself up. It was important that the three of you disagreed about some things as it makes sure that each idea or theory is fully tested. There was no right or wrong so be proud of the end result. One of the reasons I stopped designing my own cab was that is was clear that in this case a small committee would get to a better answer than I could alone. TKS is right. I first came across this from Walter Harley (www.cafewalter.com). He did a spectral analysis of bass signals and came to the same conclusion as TKS. The fundamental is important but the harmonics give us more info. I would also say that your observations just prove to me that a good HPF in front of the power amp is worth its weight in gold.

There was s thread on TB I think for a mod to get a bit more gain from the preamp on the Superfly. I will look for it and get back to you. OK I have found it but there is no circuit diagram/schematic. http://vissinger.org/pages/SuperFlyMods.html I will do some more checking,back soon!

I don't know the Mag 200 but my old Mag 300 combo had a speaker output for an extension cabinet. The main point is that if a Solid State combo has that extension output the it will probably only output 1/2 power with the internal speaker. To get the extra power you will need an extra cabinet. To put it another way, with the internal speaker you will get only 100 watts, you need another speaker to get the full output power from the amp.

Magnets do not move whether they are ceramic or conventional ferrite materials.The coil is the moving part. Neos do allow the designer more scope with both the shape and size of the magnet but two magnets of equal length and with the same magnetic properties will give the same sound with the same coil, cone, surround, spider, basket when mounted in the same cabinet.

So I am still safe in Darzet then !

I realise that the design is not finalised yet but can I assume the the depth will be greater than 280mm. As I am currently planning my amp build, I don't want to have the amp overhanging the cabinet and the current favourite is 279mm deep.

[quote name='JTUK' timestamp='1411049115' post='2555950'] I think you should expect them to last and perform well if kept in a dry and reasonably stable temperature. I would suggest the cone and the suspension and any terminals do not need too cold and/or humid temps. So whilst keeping them in a garage during the summer is ok.. I wouldn't leave them in a garage all winter, myself. And the older the chassis are, the harder it is to get cone kits or find replacements so you have to get modern equivalents ..which is possible, but why make this a factor with a degree of care..?? [/quote]A cold garage is not a problem but a damp garage is. Remember that the temperature change between room temperature and thermal power will, be a much larger change than that from room temperature to even -10 celcius. As for ears changing faster than drivers, that is true and is noticeable for HiFi and PA systems but for most bass speakers, even my 10K limited 63 year old ears hold up well compared to most 8,10,12,15" drivers.

I have used most of the Everbuild products. I like Titebond as you can mix as much as you need. This is one if the bubbly gap fillers and you need to be careful to watch and clean as it sets as it is hard to remove since set. The ready mixed poly, now rebranded gator glue, I have not tried but they are D4 strength, the maximum strength specified in the European Standards. I have used their PinkGrip and that is great as long as you don't mind pink. It is the strongest gap fill adhesive I have used. They have three PVA adhesives one each of D2,D3 and D4 strength. I have only used the D4 strength and I this much better than Evostik wood glue. Any question, please ask. Incidently Ever build products are sold cat Toolstation and there is one within 5 minutes of my house.

I hope the Green Evolution Rage is not one of them Lawrence. I have one in the Garage, about two years old and never used.

It is generally thought that speakers need a "running in" period of about 100 hours however a speaker that still sounds OK over many years is probably still OK. Your ears will tell you when you need to change.

I have already said that the supposed valve sound comes mainly from the power amp and power supply, so a hybrid where the preamp is valve based is not very useful. A valve power amp will give up its characteristic sound usually when being driven hard so if we want to play at low or medium power, the effect is very small or non existant. So for many applications, there is no need for a valve amp. Add the fact that many or most valve amps need rebiasing when a valve is changed, can develop microphony and weigh a ton... In my opinion, a good, flat, quiet, powerful silicon based amp together with the correct techniques and carefully chosen effects is much more versatile.

250 watts will not be noticeably louder than 200 into the same cab.

It is bad because the two outputs feeding each other. As said earlier, use a small line mixer.

Bill is correct. A square wave is like an infinite collection of sine waves in its purest form. If you gave square wave going into a speaker it will sound awful but will not damage a speaker per se. It becomes a problem when approaching the thermal limit of a speaker. At that point you could be putting approx 40% more power through the speaker than if you were putting a pure sine wave into it. Of course unless you play bass flute or whistle through your system, you will not be putting a sine wave through your system. I can find you many men who bash their heads against walls every day for years and some if them will escape brain damage. Overpowering your speaker is the same, some will last years but some will fail the first time you go to 11.

[quote name='monsterthompson' timestamp='1410390748' post='2549061'] Under-power is bunk. I will say I've found lower power amps don't push hard enough to get good tone. For example, I had a Crown XLS 1000 power amp, and I could tell when it was in bridge mode (for more watts) because the speaker reacted differently, and the sound was fuller even if the volume was roughly the same (I wasn't using any form of measuring device). I'm not sure what was going on in the guts that made it that way, but it was noticeable. [/quote] if you bridge an amp you will get 3-6db more power output at the same settings on the preamp comlared to a single channel.

Everyone take care when using power saws. Duke from Audio Kinesis had a fight with a table saw and lost. He is now only able to offer a Hi Three. Duke has been designing and building cabs for many decades so it can happen to anyone,

[quote name='taunton-hobbit' timestamp='1410198093' post='2547055'] 'Hybrid' amps are nothing new - stuff a valve input stage on to a class D solid state and you get something fairly close to a cooking great valve amp without the drawbacks - try it with a Crown xls - it's an interesting mix.......... [/quote] Most hybrids have a valve front end but much of the valve sound comes from the power supply and output transformet. Surely an SS pre with a valve power amp ia the right way? I should add that as an electronic engineer of 62 years, no valve will find its way into my pre amp or power amp.

As I have owned both an AC30 and a Selmer Selectatone 30 ( i wish I still had them both) ,I can atest to their volume. Not as beefy as a 4x12 with a Marshall/Sound City/HiWatt/Simms Watt head but plenty where it reallly mattered. Is it me or was their just more balls in those early british valve Combos? Got to also say the AC30 bass was a POS.

[quote name='Bill Fitzmaurice' timestamp='1410178204' post='2546782'] Most cabs reach maximum driver excursion at no more than half their rated power, so that's all you need to get full output from them. You can have more power on tap if you wish, but you simply won't use it. The same applies to PA. Where PA differs to some extent is with respect to high frequency drivers. They can be harmed by clipping, so plenty of amp power used to be a necessity to prevent that, but clipping is very effectively prevented with electronic limiting, something which was not an option when this was written: http://www.jblpro.com/pub/technote/lowpower.pdf As for the link's take on guitar speakers, he misses that by an even wider margin. Most guitar drivers have such short xmax, 1mm or less, that they reach maximum uncompressed output in the lows with only 10-15w input. The power required where guitars get most their decibel output, between 500 and 2kHz, is quite low, and doesn't require massive driver capacity to handle it. Anyone doubting that has never been on the receiving end of a Vox AC-30. [/quote]

[quote name='JTUK' timestamp='1410180092' post='2546821'] Horrid little things [/quote]i think you are being harsh on the OP and others. They are entitled to their opinions😎

I had a BLX130. Trace used to use the same power amp in all the mosfet amps but change the number of mosfets for higher powers. I suspect that the 130 was 80 watts with the internal speaker but would output 130w when connected to an external 8R cab. I found the standard BLX130 OK for rehearsals and small pub gigs but but great for almost anything when used with the extension cab.

So the questions are: 1. Are you getting a replacement or just giving up on the MiBass? On a more technical note, 2. Why fit fan when the power amp is designed to be used without one? 3. Is the fan on all the time or or temperature controlled?

They are welcome to it. Once water gets into an electric circuit it just keeps corroding away until something fails.It does not do paper cones a lot of good either.

I was chatting to Blue Aran the other day re stock on the SM212 and told them about this thread. After reading it they sent me this response; "I had a bit of a read of the thread, looks very interesting. There is a driver that is mentioned mid-way through: Faital Pro 12PR300 http://www.bluearan.co.uk/index.php?id=FTP12PR300AP It won't be everyone's cup of tea for this design but should certainly be a contender - it has great mid-range and is about as lightweight as they come. Assuming it is indeed suitable for this design we can do a Basschat special on these: £115 inc VAT, free delivery. We tend to keep them In order to get the price all you need to do is register on our website then email us with a link to that forum thread. Unfortunately there isn't anything we can do on the Beyma SM212 but it's already fairly well priced." I have no affiliation with Blue Aran and although the PR300 is a neo, it does not model as well as the SM212 so I will stay with that. For those that need a lightweight cab it might be an option though.