Bill Fitzmaurice

51 minutes ago, Owen said:

What is the difference between side by side and one on top of the other?

Where bass cabs are concerned refer to an earlier post: the radiating surface of the 4x10 is wider than that of the 1x15, so its midrange dispersion isn't wider than the 1x15, it's narrower. Placing cabs side by side makes the radiating surface wider, so horizontal dispersion is narrower, by half. Vertical stacking also gets drivers closer to your ear level, so you hear the mids and highs better on stage.

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The internet tells me I could just whack them all along the back wall or along the front of the stage (https://www.soundonsound.com/techniques/bass-place).

That's subwoofer placement, not bass cab placement. Subs don't radiate midrange, so side by side and vertical gives the same result. 

1 hour ago, DGBass said:

Yes, both cabs are damped with the same material but the MM does have a litte less of it. Mainly so as not to obstruct the porting mechanism at the rear of the box.

I suspected that. The damping reduces internal reflections back to the cone. Those reflections arrive back at the cone at various degrees of phase, depending on the distance from the cone to the reflecting surface, and the frequency. They can cause both peaks and valleys in the speaker response. Valleys tend to not be particularly audible, but peaks are.

I suspect the difference in brightness is related to the amount of internal damping used, if any.

2 hours ago, BigRedX said:

You'll get greater variations in sound with two different cabs then you will with a single cab or multiple identical cabs.

That's part and parcel of the myth. To some extent it was true 50 years ago, when there was enough difference between the response of, say, fifteens and tens that there could be some benefit to using both. That's when the myth began. But for the last thirty years the only difference between drivers based purely on their size is the angle of midrange dispersion. The larger the driver the narrower the angle. That's why midrange drivers are smaller than woofers, and tweeters are smaller than midranges. It's about dispersion as much as it is about extension.

Take the venerable 1x15/4x10 for instance. Time was that 1x15 would probably have had a driver that went lower than tens, especially as the tens were likely guitar drivers. Being guitar drivers they would have gone higher than a bass fifteen. There was some benefit to mixing them, although ideally there would have been a crossover employed. That ideal was seldom present.

Flash forward to the mid 90s or later. 4x10s are now loaded with true bass drivers, so they may go just as low as a 1x15. They have more total driver displacement than a 1x15, so not only do they go just as low, they also go louder. The 1x15 has gone from being the anchor to being the weak link in the chain. OTOH the radiating surface of the 4x10 is wider than that of the 1x15, so its midrange dispersion isn't wider than the 1x15, it's narrower. So where's the benefit of using a 1x15/4x10 today? There is none, unless they're at least 30 years old.

1 hour ago, Phil Starr said:

 why is so much of the advice not to do it when clearly it can work so well

Because as with Forest Gump's box of chocolates you never know what you're going to get. Some combinations work, some don't, and there's no way to know without trying. If you have a shop full of cabs to try that's OK, but otherwise it's not practical. With identical cabs you know what you'll get, and it will be even better from the additional sensitivity with two than with one. On that, virtually any two cabs together will sound better than either on its own, because of the increase in sensitivity and radiating area. Whether two different cabs will sound better than, or even as good as, a matched pair you can only know by trying all of the possible permutations.

3 hours ago, Tee said:

I think the original 2x15 cabs were around 300w.

They were, loaded with JBL D140 rated for 150w each, and that was in the 60s. The more or less current equivalent 2226H are 600 watt rated. It was the JBL drivers that made Sunn 200S the best bass cab in the late 60s. Fender used them as well in their Dual Showman, but that cab was sealed, which gave poor results with the low Q JBLs. The Sunn was ported, so they worked much better. Sundholm called them rear-loading folded horns, but they weren't. He called them that because he didn't know what a rear-loaded folded horn was. His seat of the pants design was a reverse taper bass reflex. Even though he didn't really know what he was doing they still worked a lot better than sealed.

The size of the motor/voice coil doesn't directly relate to driver sensitivity, but as often as not higher sensitivity drivers have large motors/coils. What is curious is the 100w rating of the 2x15. The reason behind four inch voice coils is they can shed heat better than smaller coils, allowing for high power handling. A four inch coil only rated for 50w makes no sense. That's not the only thing on their site that makes no sense.

As I recall the original Sunn amps made by Conrad Sundholm used Dynaco kit power amps.

It may look unorthodox but if your drummer has trouble hearing you turn the lower cab towards him. It won't affect the non-directional low frequencies but it will allow him to hear the directional mids and highs.

1 hour ago, Rubbersoul said:

It I'd be looking for a cheap 15 to complement the 210.

The concept that a 15 complements a 210 is a myth. Sometimes it works OK, but not always by any means.

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it's really the power handling I'm interested as I don't want to put an 8 ohm cab on if it can't handle the power from the amp.

The thermal power handling is moot. What matters is the mechanical power handling, a spec which unfortunately never makes it into the advertising. Doubling the driver count with identical drivers quadruples the effective mechanical power handling, while avoiding potential destructive phase interactions.

The only sure match is another cab loaded with the same drivers.

If I was to have a speaker for upright use only I'd load it with an eight inch. The upright low frequency limit is much higher than electric bass, so there's no need for the lower response or low frequency output capability of larger than an eight. An eight will go high enough to make a midrange and/or tweeter unnecessary, and will have 1.5 times the midrange dispersion angle of a twelve. For higher output requirements I'd use a stacked pair.

On the low frequency limit, the two instruments do have the same fundamental frequencies, but the main content lies in the harmonics, not the fundamentals. When an open E is played on electric most of the content is at 82Hz and higher, when played on an upright most of the content is at 123Hz and higher.

The LPad goes between the high pass filter and the tweeter, so it's 8 ohm. Besides, you can only find them in 8 ohm. Where questions are concerned better to ask than to have a problem.

That's normal for +/-3dB. If you see a bass cab claiming response to 40Hz that's probably -10dB. It's absolutely not -3dB.

They may be back but at those prices it won't be for an extended stay. 🤥

1 hour ago, alexa3020 said:

Ha! At my last gig, everytime the drummer hit the kick there was some weird feedback on stage that sounded very similar to a bass note! Leaving completely unable to hear my own bass at times! That was a fun gig luckily it was inaudible out front.

I heard that effect quite clearly through the PA at a concert last winter. It created a constant drone that was so bad that not even halfway through I left. It was Max Weinberg's (of Bruce Springsteen's E-Street Band} band, with a supposedly pro at the FOH. How a deaf guy got that gig I can't figure.

If in doubt before the full sound check take your bass and DI into the FOH and run into the board from there, making sure that the spund from the PA is what you want, not what he wants. If necessary remind him of the pecking order. No one ever bought a concert ticket based on who was running sound.

An old story, so forgive me if you heard it:

A 9,000 seat outdoor venue near me was being threatened with closure over noise complaints, low frequency noise in particular. They hired a 'professional' company to come up with a solution. Said solution was a cheap PC with sound level software, with a mic that measured the level in the FOH.  An alarm light lit if the level they'd hit exceeded the standard that they assured would not be too loud in the area. For a full season the light never lit, yet the complaints increased with every concert. For this the venue paid them $25,000. 🤥

Just before the start of the following season, on the threat of being shut down, they hired me. The first thing I noticed about the gear they had and the standard that was being used was that the levels were being measured with 'A-weighting'. They were upset to say the least when I told them that 'A-weighting' doesn't measure low frequencies. 😄

The main problem is PA subs that go an octave lower than bass cabs. The cure is to high pass the bass channel strip around 60Hz. FOH guys who are also bass players or recording engineers known this. But those who aren't usually don't.

That rarely happens. Most sound men make it what they think bass should sound like, and they're usually wrong. My number one complaint about concert sound is pounding deep bass that has no resemblance to what players want for tone, at levels that drown out the rest of the band. 

Alex is correct insofar as what he talks about, which is frequency response. As to whether by looking at charts you can tell what a speaker sounds like, you can. But that's 'charts' in the plural. A waterfall chart will tell you most of what a frequency response plot doesn't. Then there's THD, polar response, power compression and a half dozen more. Speaker emulation devices adjust frequency response, some high end studio plug-ins can adjust some other parameters, but none can do it all. The main thing they can't do is to vary all of the various parameters as a function of the volume that the speaker is being played at. If your charts are going to be truly accurate they have to be measured at various power levels, because they will change at various power levels. Even if you had software sophisticated enough to duplicate all of the charted results at one given power level it wouldn't be able to do so at any power level without an unaffordable level of processing, along with the necessary interface to tell the software at what power level it's operating at any given moment. That would require something with capabilities similar to Klippel analysis. It would be less expensive to run six different speakers.

Speakers reproduce the signal that's sent to them by the amp. In this case the amp is sending hiss. You don't hear it through the woofer because woofers don't respond to high frequencies.

There are professionals, in that they get paid for what they do, and there are professionals, in that they know what they're doing. This bunch doesn't know what comb filtering and power alley are, let alone how to prevent them. They had both, with not only poor sub placement but also side by side tops. 🤥

The LPad can't hurt, but since you have dual woofers at 4 ohms that will even things out a bit. You usually have to reverse wire the tweeter with a 2nd order/2nd order crossover, another reason why I never use them. But it doesn't hurt to run a 2kHz tone through the system before you button it up, trying the tweeter wiring both ways, going with whichever is louder if there is any difference.