Bill Fitzmaurice

That does not appear to be Eminence. Most Eminence bass drivers have a large pole piece vent in the magnet and/or an extended bump of the back plate.

Looks good, but rotate the 2x10 to place the drivers vertically. Both you and the audience will hear it better.

1 hour ago, BassAdder27 said:

Yes like that but not tilted back ( head would fall off ) 

With a bit of ingenuity you can find a method of securing the head. In my case I attached two inch high feet to the front edge of the amp that hang down far enough to hook over the front of the cab. Where hearing what you're doing is concerned, especially on a tight stage, tilt back is even more effective than lifting.

This, or something similar:

https://www.amazon.com/Fender-099-1832-003-Amplifier-Stand-Large/dp/B00LJY4886/ref=zg_bs_11973191_5/138-0471784-6307153?pd_rd_i=B0891LCND5&th=1

I very much doubt that happened in shipping, if it had the grille would have been bent. Have them re-coned. Once pulled they should be identifiable.

On 06/04/2022 at 14:17, Smiles said:

Hi guys has anyone had experience with the Ampeg svt 610 hlf 

As they’re only a 600 watt cab

Ampeg is conservative with their power ratings. Where farting out is concerned that happens when the drivers run out of excursion. There are many tens rated at 250w that have no more excursion capability than the 100w rated Ampeg ten.

Quote

I would think that stacking two 2x10 cabs vertically might be a good idea if is all about having something audible at ear level. That would actually be a taller stack than a 6x10 and much more portable, easier to move and take up less space in the car/van.

+1. The 410 is the poster child of how not to build a bass cab, as neither you nor the audience will hear it anywhere near as well as those same four tens vertically stacked in a pair of 210 cabs.

That's not necessarily a bad thing, as you can tame too much low end by pulling down the low end EQ.

1 hour ago, Al Krow said:

This is what confuses me: there's a massive "FRFR" thread where bass players swear by a single 12" PA speaker being perfectly adequate as their sole backline without a sub.

It depends on the twelve. One that will do this job isn't going to be had on the cheap, nor will it deliver good lows when stuffed in a too small enclosure, especially when said enclosure is up on a pole in front of the stage as is required for PA, which means it won't get ground plane or rear wall low frequency reinforcement. That results in as much as a 12dB reduction in low frequency output compared to on or close to the floor and close to the rear wall. 12dB is the difference between one twelve and four twelves. The concept of boundary reinforcement, like Hoffman's Iron Law, should be just as familiar to bass players as are the notes E-A-B-D. 

3 hours ago, Al Krow said:

Cheers Bill. 

Should RCF 312As cut it, based on their spec in your opinion / experience or are we realistically going to need to go north of that in terms of spend? 

They don't provide adequate specs to draw a conclusion from, but I doubt they're going to do the job without subs at other than coffee house levels.

On 04/04/2022 at 04:24, Al Krow said:

compact budget PA which can also handle bass

Google 'Hoffman's Iron Law', though it should be something every bass player is very familiar with. If it's going to be small and it's going to go low then it can't have high sensitivity. One can get around low sensitivity with enough power, and premium drivers that can make use of it, but that removes 'budget' from the conversation.

I've never used a pedal, never needed or wanted one. I had a raft of them when I played guitar, but with bass all the effects I needed were my hands.

He used to do that, and a lot of other things with varying degrees of success, but he's been running a conventional Ampeg setup since at least 2011, when I last saw him.

If this is just to make use of a box and a driver you have on hand without any expectation of a great result then use plywood per above. But otherwise I wouldn't do it unless loudspeaker modeling software reveals that the box and driver are a good match.

6 hours ago, thebrig said:

The Barefaced ONE10t states that the Max amp power is 250W RMS (500W clean)...

What exactly does "clean" mean?

I have no idea. It's not like Alex to create terms of out thin air. I'd ask him.

2 hours ago, Waddycall said:

So a given cab  at a given frequency can handle a certain amount of voltage swing before it suffers mechanical damage?

Yes.

Quote

What I think I’m struggling with is the difference between a voltage swing of equal magnitude/amplitude from a single channel amp and a bridged amp.

There is no difference, a volt is a volt. The question is whether or not you need to bridge to realize enough voltage swing to get full output from the speaker. If you don't then there's nothing to be gained with bridging.

Cone excursion. When impedance is halved excursion is doubled for a given voltage swing. When it's doubled excursion is halved for a given voltage swing. One cannot say x watts will result in y decibels, or that x watts will result in y millimeters of excursion. Those equations do not exist. One can say that x volts into z ohms will result in y decibels, or that x volts into z ohms will result in y millimeters of excursion.

2 hours ago, Dad3353 said:

the same 40v limit, is bridged with an identical, but phase-inversed, '-40v' amp. The cab 'sees' an 80v swing. That's what bridging achieves; 'double' the power for the same current. OK, it's a simple view, but that's the gist of it. 

When you double the voltage swing into a speaker the cone excursion increase is the same as what occurs with four times the power. That's what leads to mechanical damage.

Quote

am I missing the point?

Yes. You're not considering impedance. Engineers seldom look at power, we look at voltage and current, the former with respect to the capability of speakers, the latter with respect to the capability of amps. Power is an attempt to simplify the equation, but in truth it just further muddies things. 

Voltage swing is what determines cone excursion, which determines volume. Power is what you advertise to convince people to buy your product.

This question comes up often enough on my forum that I added an FAQ reply:

When should I bridge? The answer is almost never. Forget about the silly power ratings that manufacturers post for bridged output, that's just advertising piffle aimed at the unwashed masses. Bridging isn't about power, it's about voltage swing. You use it when your amp doesn't have enough voltage swing to drive the speaker to its displacement limit. Nine times out of ten that's because the speaker has a high impedance, say 16 ohms. The tenth time is when your amp is rated at less than a quarter the power output that your speaker is.
If you do bridge when you don't need to the doubled voltage swing quadruples your chances of blowing drivers. Bridging into multiple cabs also can cause the amp to overheat, as bridging typically doubles the amp minimum load impedance, while using multiple cabs lowers the load impedance.

Quote

power amp manufacturers seem to recommend choosing an amp that’s twice the rated power of the cabs. I guess that makes sense for a fixed venue type installation but if I followed that advice I’d be connecting a 2.4kw amp to my 210

Not likely. There may be tens with a thermal rating of 600 watts, but I'm not aware of any that will take more than half that before reaching their mechanical limit. Also, power amps are intended for PA use, where plenty of headroom is desirable. That's not necessarily the case with instrument amps.

1 hour ago, DaleASmith said:

 

😂

That's not what I meant, but I guess you already know that...🙂

It's not what you meant, but clipping is clipping, no matter where it occurs in the signal chain. It can be bad for tweeters, that's why guitar cabs don't use them, but will never hurt a woofer.  http://www.bcae1.com/2ltlpwr.htm

That's the Myth of Underpowering, and it's just that, a myth. If amp clipping, or clipping anywhere in the signal chain, hurt woofers guitar players would be swapping them out at every break. Clipping is only potentially dangerous to tweeters, because the high frequency content is abnormally high. And we don't play sine waves.

Farting out occurs when the combination of power and frequency attempts to force the cone to travel beyond its mechanical limits. The cure is to reduce the volume and/or low frequency EQ. The cab power rating doesn't indicate whether an amp can push the cone too far because that rating is thermal, not mechanical. Cone excursion goes up as frequency goes down, so a 500 watt signal may not cause over-excursion at 500Hz while a 50 watt signal at 50Hz may. The simple answer to farting out is that if one cab won't handle the combination of volume and bass EQ that you use you need two or more cabs, or one cab with more driver displacement.  https://barefacedaudio.com/pages/how-speakers-move-air-volume-displacement

2 hours ago, Dad3353 said:

 

The speed of cone movement is the frequency, no..? 

No. Let's say the frequency is 100Hz. That means the cone must go from rest to full outward excursion to full inward excursion and back to rest 100 times per second. If it does so over a distance of, say, 6mm it must move six times faster than it does over a distance of 1mm. How cone velocity can affect the result is explained here: http://www.readresearch.co.uk/loudspeaker_papers/klipsch_modulation_distortion_article_1.pdf

That's what Chris Squire did as well. I doubt he used a crossover. He probably just plugged into both. Most amps of that period had parallel input jacks, making it very easy to daisy chain amps.

Xmax is the distance the cone can travel before distortion becomes severe. The longer the xmax the louder it can play. The best way to compare different drivers is with speaker modeling software. The program I use the most for sealed and ported cabs is WinISD 0.7. With it you can see the effects of the box size and tuning, and see Maximum SPL, which is determined by both the voice coil power limit and xmax.