Bill Fitzmaurice

Watts aren't meaningless, but almost. Otherwise how do you explain the Ampeg B-15? 🤥

What we used to call gear groupies. ☺️

The return jack is a mono 1/4 inch. It won't work with a stereo input.

Could be, but plugged in? the last time I saw ZZ Top they had two dozen or so Magnatones on the stage. I asked their road manager how many they were actually using. He told me Billy and Dusty were using two apiece, the rest were 'eye candy for the kiddies'. 😄

Here's the deal on Sovtek and Chinese tubes: In the West military devices, like radar and communications, converted to SS early on, being much lighter than those powered by tubes. The USSR didn't have the SS tech that the West did, so they stayed with tubes much longer. Tubes also had the advantage of being immune to electromagnetic pulse, which fries SS devices. That was a concern during the Cold War. Without the demand for tubes for the military and civilian devices other than musical instrument amps, and because making tubes is environmentally a problem, Western tube sources disappeared. Since Soviet gear still used them, and they didn't care about environmental issues, tube suppliers in the Soviet bloc remained. Musical instrument amps remain as the #1 users of tubes, most of which still come from Russia, China and Slovakia. Those that are still made in the West are much more expensive, as their manufacturers have to adhere to environmental regulations that pretty much don't exist in Russia et al.

And for that there's this:

Those are tube conversion sockets, allowing the use of a tube other than the original. https://www.tubedepot.com/t/other-stuff/yellow-jackets?srsltid=AfmBOorm7EPnxQenwo22TciGXI6p0wev-H5TymKMmUU23zzT-vgP2Z51 I vaguely recall a SS tube replacement existed back in the day, but if it had been successful it would still exist. There was a big scramble for a SS tube replacement when most tube sources went out of business in the 70s-80s. Nothing much ever came of it.

Dispersion, dispersion, dispersion. It's inversely proportional to the size of the source. The main reason for larger drivers is they can move more air than smaller drivers. If you use multiple smaller drivers you can move just as much air with higher efficiency and wider dispersion so long as they're vertically aligned. Fifteens work best where dispersion isn't a concern, which means either in sub or in 2 way or 3 way cabs where the fifteen is only run to 800Hz or so.

Do a search. This topic has been thoroughly discussed in multiple threads. It's unfortunate that your guitarist didn't do his homework before buying the DXR15s. You'd get a much better result with a pair of DXR10 and an 18 inch sub.

Playing arenas with no PA? 😄

Avoid that. It makes it harder to hear them, for you and the audience. Vertical sources always work better.

Feet don't affect the sound but they do make the cab more durable. I can't fathom any reason to not have them. However, the Markbass cab corners do extend past the panel, so they do act as feet of a sort. They also interlock when cabs are stacked, so that's the reasoning behind them. For added protection I'd add feet to the cab that's going to be on the bottom of the stack.

No. That's the myth of underpowering, which like Nessie and Robin Hood just won't go away.

It is if you do it right. Our hearing is logarithmic. It takes ten times the power/a 10dB increase in level to sound twice as loud. To account for that volume controls are also logarithmic, commonly referred to as audio taper pots, as opposed to tone controls, which are usually linear taper pots. I've seen amps that used linear taper volume controls, and the result was not linear. But it has nothing to do with the amp class.

That was covered in the thread, starting with the first reply.

Yes, it is, which is why that load must be within the secondary specs. If you want to get really picky about it you match the reflected load current to the primary current, but when you try to do that via the speaker impedance and/or the number of output valves you run into the issue that speaker impedances aren't a fixed value, they vary with frequency and the enclosure design, so you can't really get it perfect. For the most part close enough is good enough so long as you don't have a gross mismatch, like using a 4 ohm tap with a 16 ohm speaker.

The load impedance seen by the power valves is the output transformer primary. All that you accomplish by removing two valves is to reduce the current that the amp can deliver, and while that does reduce the power it's not a good idea. Guitar players who came up with that notion were only fooling themselves as to its effect, which at best might result in a measly 3dB reduction in maximum output.

A compressor that tames the initial transient peaks but doesn't have any other effect should fix the problem. I'd say whatever limiter you're using either can't do that or it's not set up correctly to do that. I used to be able to get my Hartke 3500 to go into protect mode. It certainly wasn't caused by a lack of power or headroom. But I didn't have a compressor, and it only happened when I slammed a chord at the end of a song. It didn't bother things all that much, as my feed to the PA was unaffected.

I hope it works out, but...subs have to be considerably larger than mains, which means heavier, for the same reason that basses have longer necks and larger strings than guitars. Otherwise we'd use guitars tuned an octave lower.

I paid $350 for my '65 Bassman. That was the average monthly wage at that time in the US. I paid the same for my '65 Jazz Bass.

Practical but not inexpensive. Old school drivers have xmax values averaging 4mm. A driver with 8mm xmax is the equivalent of two drivers with 4mm xmax, but they can cost twice as much as well.

But you're the bass player. You're the smart one in the band. At least it's always been that way for me. 😄

The contents of this thread thoroughly explain why tubes and SS are different, and why watts don't define loudness or tone. Folks like agedhorse, Phil Starr and myself have been posting this information for as long as there have been forums to post it on. Can't say we haven't tried.

+1. Whatever you have for tops requires a sub, or subs, with no less than twice the air moving capacity. The average moderately priced twelve top, for instance, has some 250cc cone displacement. That puts a pair of them at 500cc. A reasonable subwoofer match would require 1000cc displacement. That means a moderately priced 18 or a pair of 15s.

Valve amps are the opposite of SS. They have a maximum load impedance, not a minimum. They can even withstand a dead short, while an open circuit can damage them. For this reason one of the output jacks on Fenders was a closed circuit switching jack that shorted the output when there was nothing plugged into the main speaker jack. It also meant no signal passed if you plugged into the extension jack instead of the main jack, which pretty much every Fender owner discovered at some point, to their great consternation.