Bill Fitzmaurice

A valve amp is unaffected by a shorted output. For that matter Fender valve amps use a switched speaker jack that shorts the output so that the amp won't be damaged by what will hurt it, which is no load. That's why they don't work when you inadvertently plug in to the extension speaker jack rather than the speaker jack. SS amps that lack short circuit protection circuitry, which are rare, can blow output devices and more with a shorted output cable.

Actually it does. With no load on the high pass filter it can exhibit a very low impedance within its pass band, which can create problems. The safe way to remove a tweeter circuit is to disconnect the crossover entirely, wiring the woofers direct to the input jacks.

Since it was open back it was worthless for bass above bedroom or low studio levels. It was designated as Fender's bass amp only because it was the largest they made that year. The Concert guitar amp was essentially the same amp with tremolo, built on a newer chassis.

https://www.talkbass.com/threads/2x12-vs-two-1x12-cabs-pros-and-cons.1319015/

Assuming the same drivers, the same total internal volume, and the same port tuning in the case of a ported cab, this is a case where 1+1=2, pure and simple. What discussion on this simple concept could possibly take five pages I can't imagine, and life's too short for me to bother finding out. Arguing about minutiae ad infinitum is why I left Talkbass ten years ago.

The meaning of warmth isn't too difficult to imagine. The same for boom, or harsh. But when you get into the terms used by oddiophiles it's easy to be left in head scratching mode. I have no idea what they mean by 'air', other than that they have far too much of it between their ears. And of course there's 'fast bass'. WTF?? Did the bass player finish the song three bars before the rest of the band? 🙄

For most warmth is considered as a strong midrange with not a lot of low end, which is what I'd expect from his current arrangement.

Not in a Southern Baptist church service. The scene with James Brown as the pastor in 'The Blues Brothers' was pretty accurate. https://www.youtube.com/watch?v=PZpH9Khn0E0

Chances are you've reached what your cab is capable of putting out with your current amp. Power doesn't matter. What does matter is driver displacement and speaker sensitivity. The 6dB increase in voltage sensitivity from adding a second identical cab and the 6dB increase in maximum displacement limited output are the equivalent of quadrupling power if your 210 could handle it, the possibility of which is slim to none, and Slim just left town.

Two would give slightly less low end than one and the midbass would boom.

The BL12-200x are about as flat as you're going to get in that enclosure. What you call very warm I'd call a weak low end, as its response is -10dB at 55Hz. That's not the fault of the drivers, it's what you're going to get from a sealed enclosure that small. If what you're after is stronger lows you've got to go larger. If I had to use that enclosure I'd load it with one Eminence BP122. It would be -10dB at 36Hz, and one BP122 in that enclosure would be capable of more output than two BL12-200x.

The last matched head and cab I owned was a '65 Fender Bassman, which I bought new. That's how long it's been since matching was relevant, and back then it was hard to find separates sold as new anyway.

Modern speakers have rendered both the 300w valve amp and 8x10 configuration unnecessary. If you want to keep the Ampeg tone I'd look around for a V-4B.

That's normal, it happens in every room, and the smaller the room the greater the effect of boundary sourced cancellations. It's also the explanation why the bass can be louder in the back of a club than on stage. On stage the boundaries are close enough to the speaker and you for cancellations to occur, while even twenty feet out there are no cancellations. But this is something that happens in the bass and midbass, where there is no directional content. Dispersion only narrows in the mids and highs, typically above 300Hz.

That would be the way to do it, placing the full range drivers adjacent and the low passed drivers at the top and bottom of the stack.

It doesn't have balanced speaker outs, and while speaker outs are technically unbalanced they're never referred to as such. Both of those would be line level.

Quite right. Any time you have side by side sources they will suffer from destructive interference off-axis in the high frequencies and reduced dispersion in the mids. Barefaced gets around the destructive interference in the highs by removing the high frequency content from one side, but within the midrange frequencies where both sides are operating dispersion is still halved compared to a pure vertical line of drivers.

The cone doesn't stop moving, but it moves a lot less at the tuning frequency. This excursion chart shows a fifteen in a ported cab with 45 Hz tuning at 200 watts input. At 1 watt input excursion at 45 Hz is a mere 0.07mm, so while not immobile it can appear that way compared to above and below that.

Quite right. The better method is to take the eyes out of the equation via double blind testing. I can't recall any such testing ever being posted on a bass forum. If it was undertaken the results would likely be quite interesting, as in this case: http://seanolive.blogspot.com/2009/04/dishonesty-of-sighted-audio-product.html

The wavelengths that a port produces range from 12 to 25 feet. That makes an obstacle some 2.5 feet wide, as in a speaker enclosure, invisible to them. They go around it as if it wasn't there. Where the cone radiation is concerned those wavelengths also go fully around the cab, in the opposite direction, up to where the enclosure baffle is one wavelength in dimension. 2.5 feet is one wavelength at 450Hz. That explains why when you walk behind the cab, or when a drummer is behind the cab, the lows and midbass are still heard, but the mids and highs aren't. If your drummer isn't in front of the cab and wishes to hear your mids and highs and you have two cabs the best placement is to stack the cabs, with the bottom cab aimed at the drummer.

FWIW I use front porting on most of my designs because most people buy with their eyes, not their ears. How a rear firing port works as well as front firing can be better understood if you consider the case of sub woofers, which operate within the same frequency pass band as ports. SOP for those in the know is to aim them at a wall, or a corner. They work better that way than they do facing away from the wall or corner.

Google 'omnidirectional'. Not only is port radiation omnidirectional, cone radiation is as well up to about 200Hz. A port output can be choked off if the port is placed tight to the wall, but even an inch or two of space will eliminate that. Without a doubt you may hear a difference between front and rear ported, but it's not due to the port location.

Port placement doesn't matter, as the radiation pattern from a port is 360 degrees. What does matter is the size of the enclosure. Larger enclosures go lower and louder. In most cases the reason for putting ports on the back is that the enclosure is too small to fit them on the front. Boom is also typical of too small enclosures, and it has nothing to do with port placement either.

In order to find drivers with similar specs to the Aggy drivers one must have the specs of the Aggy drivers. In order to find drivers with different specs that still work well one must have the complete dimensions of the cabinet interior, including the port if there is one. Having a 4 ohm load complicates matters, as you'd have to use either 4 or 16 ohm drivers, which limits driver choices.

Ampeg uses a 24v aircraft bulb. As for the need to replace it, it's either functional or it isn't. In general crackling from a tweeter is caused by insufficient crossover slope, which results in over-excursion of the diaphragm.