Bill Fitzmaurice

Assume the port is 4 inches diameter, which gives an area of 12.5 square inches. If the floor/wall is an inch away the area between the port circumference and the flat surface is 12.5 square inches, so not only is the port not blocked, it's not even constricted.

It depends on how skilled the cabinet designer was, and whether the prototype was tested to be sure of the result. I can see an inch being OK under those circumstances. It's easy enough to know if it's correct, you just run an impedance sweep to see what the in use tuning frequency is. I wouldn't blindly assume that was done, though. I've seen too many cab designs that never should have made it past the drawing board to do that.

You'd only be able to tell with two otherwise identical cabs.

A cab that's tuned too low is not going to be as loud in the lows as one that's correctly tuned.

If the feet are too short it has the same effect as being too close to the wall with rear ports, although what happens probably isn't what you might think. When the distance is short enough the space between the speaker and the floor/wall becomes an extension of the port, lowering the tuning frequency of the cabinet. That's not a good thing. OTOH a well engineered bottom ported cab would take advantage of this and make the feet the right size so that the length of the port inside the cabinet could be shortened, allowing a reduction in the cabinet size.

You can't go wrong with Ampeg.

I agree that used is the way to go, but don't settle, and in the case of the 410TVX I think you would be. The drivers that Hartke uses are an unknown quantity, so I can't venture an opinion there.

It's not a dumb question, though it is a common one. You might want to reconsider the 410TVX. The Sheffield drivers it uses are entry level, while the 18mm MDF construction is overly heavy yet not durable. The 2.5mm xmax of the Sheffields means that while they can handle at least 75 watts each thermally they're mechanically limited to around 25 watts each. There are 1x12s that can put out more than the 410TVX.

Do you play with the amp dimed and ignore the warning of impending doom that heavy distortion signifies? If so you can blow that cab with a fifty watt amp. If you play at sensible levels and turn it down if the speakers sound strained you won't harm it with a thousand watt amp.

There is no ideal amp wattage, for any driver. The usable range tends to be between half and twice the driver thermal rating. For a K140 that's 75 to 300 watts.

It's not going to be made up, but even Eminence uses a pass band averaged figure, which doesn't say anything about what it will do where it matters for bass, below 100Hz. Besides, if you don't know what your original driver has for response there's no way to predict how a replacement will compare.

In general higher sensitivity is realized at the cost of low frequency response. That's why guitar drivers tend to have higher sensitivity than bass drivers, which tend to have higher sensitivity than PA subwoofer drivers. However, you can't trust manufacturer sensitivity ratings, as they tend to play fast and loose with the details, like at what frequency it was measured. 105dB/watt seems wonderful, but not if it was measured at 2kHz. The only way to be sure if a driver swap is worthwhile is to use speaker modeling software to compare different options. The fly in that ointment is that it's usually impossible to get the necessary Thiele/Small specs on OEM drivers.

For that price you could not only make your own, you could also buy the tools to make it. 🤔

I'm not wild about being down 14dB at 50Hz. I'd go with a larger box and lower tuning to get 50Hz no more than --6dB, otherwise you might as well not have an E string. -6dB at 50Hz is my benchmark for a ported bass cab. As for the peaky response around 100Hz in your examples that's what results in boom.

You can try David Coomes, Doncaster, UK. [email protected] He builds cabs of my design, I don't know if he does any others.

I know that Ampeg used four conductor XLR for a while, four conductor so that one wouldn't plug an amp output into a console input. It was better than 1/4 inch, not as good as Speakon. A major problem with XLR is that they couldn't handle large gauge wire. I used some speaker connectors back in the 80s that resembled giant oversized XLRs. I don't remember the brand name, they were essentially put out of business when Speakons came along.

Inevitable if you insert or remove a plug when the amp is powered up, which one should never do, otherwise no worries. The man problem is the very small contact area between the jack and the plug tip. It doesn't take much corrosion to make for a bad connection, so the plugs should be treated on a regular basis with contact cleaner, which will migrate to the jack to keep it clean as well.

1/4" can be very finicky. Maybe it's because they don't like being asked to do something totally different than what they were designed for, 20th century telephone switchboards. 😏

Simple solution, use the Speakons.

Two of the most successful studio monitors of all time were the Yamaha NS10 and the Rogers LS3/5A. Google them to see response charts that show both to be about as flat as the Alps.

It's not difficult. Whether or not it's worthwhile is a different question. Why advertise anything that it's not? To make a sale.

Maybe they sound like valves, maybe not, but unless they come out with 6L6 or EL34 replacements they still won't duplicate the sound of an all valve amp.

It's not the voice coil thermal rating that counts, it's the driver displacement. Back when my 50 watt '65 Bassman was new the Fender 212 couldn't handle it, nor could two. I eventually wound up with a pair of 412s before hitting the books and learning how to design my own cabs. In retrospect I owe Leo Fender a debt of gratitude, as he set me on the path to making my living as a speaker designer. I do agree though that 3012s would be overkill, a pair of 2012s would suffice for a lot less money. Betas aren't bad either.

I'd line that with polyester batting, it will clean up the mids considerably. I'd investigate the tuning as well, you may not be taking full advantage of the 3015 capabilities. I doubt that the cab is braced either.

I can't see the need for more than a Kappalite 3015 with only 100 watts pushing it. If you're not getting the volume you need you should be looking at a better amp, not more speakers.