Bill Fitzmaurice

It's a property of the driver. Some 15s do go higher, but only on-axis. Any fifteen is going to start beaming around 1.5kHz.

[quote name='skidder652003' timestamp='1491220210' post='3271272'] never one to question the master but..my Ampeg 410 HLF doesn't struggle with mt SVT-CL [/quote]Nor should it, the SVT being 300 watts. But that's about all the excursion of the Ampeg drivers will allow.

With only 300w the Ampeg will do the job as far as power handling is concerned. But the BF will take a lot more should you even need it to, the Ampeg won't, and it's far superior technologically.

You can use speaker modeling software, like WinISD 0.7, to reverse engineer the cab for the purpose of comparing the low frequency response and maximum output with various drivers, and the driver data sheet SPL charts will tell you the midrange and high frequency response. But you have no way of knowing how they compare to the original drivers.

Unfortunately without the T/S specs and a response chart of the G-K driver it's a shot in the dark.

Email them again for the necessary T/S specs and SPL chart, that's the only way to find drivers that are compatible.

[quote name='Chienmortbb' timestamp='1489430824' post='3256870'] Neos v Ceramic is a bit like Valves V Solid State. [/quote]Not really, as valves and SS are totally different technology. Neo and ceramic are not. [quote]Sweeping generalisations are rarely accurate.[/quote]That particular generalization is accurate.

The specs of the EV 18 and 4018LF are quite close, so cab wise they're interchangeable. The 4018LF has twice the Pe and Xmax, so it's considerably more durable. However, the EV has good on-axis response to at least 3kHz, the 4018LF to only 1kHz. That's why the OP can't hear the 4018LF over the 210 top. The 4018LF will walk all over the EV in the lows, and the 210 is all that's necessary to handle the mids and highs, but to function well together they'd have to be crossed over in a bi-amp configuration. A 200Hz crossover would be appropriate.

[quote name='geoff90guitar' timestamp='1489350183' post='3256289'] Where's that?! [/quote]You're the one that dug it up, from over three years ago. Who's your employer? Dr. Frankenstein?

[quote name='geoff90guitar' timestamp='1489330576' post='3256066'] There got to be a difference. [/quote]There are differences in drivers. None that cause an alteration in tone or any other audio attribute are related to the magnet material. Just like zombies driver voice coils are brain dead, so they don't know or care what the magnet material is, they simply react to the flux provided, and flux is flux, be the source neodymium, strontium carbonate and iron oxide, AlNico or field coils.

[quote name='geoff90guitar' timestamp='1489326528' post='3256031'] It's the Neo speakers I can't get on with - they sound like meat and potatoes WITHOUT the veg. [/quote][size=8]Zombie Thread![/size] [size=8][size=4]BTW, the magnet material has nothing to do with the sound created. [/size][/size]

[quote name='Ghost_Bass' timestamp='1489063603' post='3254053'] I thought it had the other driver pointing at the bottom for sub-lows reinforcement [/quote]That's apparently how it's configured, and that's isobaric. It's a bit different than the usual arrangement, as it makes the plenum chamber connecting the drivers large, with the vented chamber small, but it's isobaric nonetheless. [quote] Isobaric with mixed sized drivers? How well is that likely to work [/quote]It won't work as well as with matched drivers, as one will run out of excursion before the other does. This is another aspect which leads me to believe the designer is lacking in the chops department.

Everything about them says 'isobaric', so while the response to size ratio will be good, the output won't be. Watts don't matter, decibels do. The manufacturer won't reveal any details about them, while their lead spokesman seems to be seriously lacking in the knowledge department. I doubt he can spell 'isobaric', let alone know what it means.

[quote name='cameltoe' timestamp='1488899616' post='3252761'] My current cab is a TC RS212 (8ohm) and I'm wondering if I will gain anything by using a 4ohm cab instead? [/quote]You'll only lose the ability to use more than one cab, unless you have a 2 ohm stable amp.

[quote name='Beer of the Bass' timestamp='1488568206' post='3250189'] a lower impedance or a short will still run the valves outside of the operating point the designer intended and cause them to limit the current passed. [/quote]It's of far less concern than no load. That's why Fender amps used a switched main speaker jack to short the output transformer secondary when there was no speaker plugged into it. As for low impedance loads, when we were young and stupid we'd run Fenders with 1 ohm loads that never bothered them a bit.

[quote name='Chienmortbb' timestamp='1488565142' post='3250134'] If you put an output transformer on an SS amp it would behave in the same way as the thermionic valve /vacuum tube amp. However why put a huge lump of metal in there is you don't need it? [/quote]That's why SS amps stopped using output transformers in the 1960s when direct coupling technology was invented.

[quote name='Beer of the Bass' timestamp='1488559026' post='3250060'] the impedance marked on the outputs or selector is the optimum load impedance for that tap, not a minimum as is common on solid state amps. [/quote]In fact, it's the maximum. The rules with valves are the opposite of SS. Valves aren't even bothered by a short circuit, but they can be toasted when there's no load.

They might also have a very different response as well as output. Play a Jazz Bass and a Gibson EB-O and they hardly seem to be the same instrument.

[quote name='28mistertee' timestamp='1488480309' post='3249361'] So it's not a problem with the cabs then? [/quote]It can be if EQ in the amp and/or an active bass is trying to get out of the speakers what they can't give.

[quote name='Dan Dare' timestamp='1488476614' post='3249315'] aren't most cabs producing mainly harmonics at those frequencies? [/quote]They are, because the bass is producing mainly harmonics at those frequencies.

[quote name='28mistertee' timestamp='1488449924' post='3248995'] Would it be possible that the mixed drivers are the problem? [/quote]The problem is that the specs you need to know are the specs that manufacturers don't reveal. One reason why they don't is that many don't know themselves how their cabs perform, that totally botched chart from Ashdown being a prime example. Manufacturers talk about inches and watts, the two least significant factors where both low frequency extension and output are concerned. Your only options are to try before you buy, or to build your own. The big advantage to building your own is that you're not buying a pig in a poke, you know what drivers are in your cabs and what they're capable of.

[quote name='markstuk' timestamp='1488399103' post='3248682'] There is a frequency plot here [url="http://ashdownmusic.com/files/product/file/datasheet_20150224063841_74985.pdf"]http://ashdownmusic....63841_74985.pdf[/url] - not sure whether it's measured or calculated... But you see the roll off from 50 Hz.. [/quote]I don't know how they arrived at that, but a bass cab with that response would be all but unusable. The black trace looks to be the raw response of a driver, measured mounted in a wall. Not a very good driver at that. The blue and red plots appear to be predicted response charts, but what they predict is a cab with no significant low frequency output. It's almost inconceivable even with a mediocre driver that the predicted response of a ported cab would be that bad, so my guess is that the charts were prepared by Ashdown's pet chimpanzee. OP, what's most important is an accurate measured response chart, at 1 watt and at full rated power. Catch 22: Virtually no one publishes them.

Sensitivity can be compensated for with EQ. The point of four drivers is low frequency capacity. Above 500Hz or so even a single ten can cover a good sized room.

Line in is for something like a CD deck. It may be OK with the keys as well, depending how much output it has.

[quote name='xgsjx' timestamp='1488205761' post='3246750'] In a 4x10, if you were to put a low pass filter on the 2 drivers at one side [/quote]It would work very well. 300Hz is lower than you'd need to go, and it would require a high cost inductor. I'd put the filter knee at 800Hz. Use a 12dB/octave filter, 6dB wouldn't be effective enough to be worthwhile. This is something the manufacturers should have been doing for the last thirty years at least, why they haven't is a head scratcher. It would be an even more useful mod with guitar cabs, but they're all stuck back in 1968.