Bill Fitzmaurice

15 hours ago, itu said:

Full range means wider response than of a bass combo.

That's what it means, but for the most part it's not the case. By and large bass combos and inexpensive powered PA boxes use the same woofers. In boxes of similar size they'll have similar low end response. PA boxes tend to use better high frequency components, which allows a lower crossover frequency. That doesn't make response any wider. It does make for better off-axis dispersion in the mids. The main difference lies in the amp EQ voicing. Bass amps tend to have a lot of coloration, powered PAs don't. Most players prefer the coloration of bass amps. If they didn't it wouldn't be there.

They should be the same polarity, the standard is for the + input connector to be wired to the + driver lugs, but it's not guaranteed. Once upon a time, for reasons unknown, JBL had the black lug positive, the red lug negative, the opposite of convention.

2 minutes ago, itu said:

Sometimes an 8 ohm impedance speaker may be louder than a 4 ohm counterpart.

Quite right. Impedance alone doesn't define how loud a cab will go. It has nothing to do with power. The reason a 4 ohm speaker will go louder than an identical 8 ohm speaker is excursion. An amp at the same settings will deliver the same voltage into both, but the excursion of the 4 ohm speaker will be longer, so it will be louder. The fly in the ointment is if the speakers are identical other than impedance. They almost never are. If you compare the T/S specs on the Eminence Kappa 15A and 15C, one of the very few drivers made in 4 and 8 ohm versions, the rest of the specs aren't the same. Even the DCR isn't doubled from the 4 ohm to 8 ohm versions, they're 3.68 and 5.22 ohms respectively. Most significantly, the xmax of the 4 ohm is 2.44mm, that of the 8ohm version 4mm. That being the case the 8 ohm can go significantly louder than the 4 ohm.

On 02/05/2023 at 16:37, BillyBass said:

Someone should start a forum 'bannedfromtalkbass.com'.  There are loads of you!

If they'd banned jerks who went on endlessly about that which they knew nothing about I might still be there. There are three types who do gear forums: Those who want to learn, those who want to teach, and those who want to argue. I walked away when those who wanted to argue took over the place. 🤥

It is high passed. That's not something often seen with bass amps but it's SOP with PA subs. To do it with bass amps you'd use a Thumpinator or the like.

250w mechanical requires 8mm xmax.  One of the best, and most expensive, tens is the Eminence KL3010LF, which has 8.5mm xmax. You won't find it in other than expensive boutique cabs. The more typical Deltalite II 2510 xmax is 4.2mm. It reaches xmax at 100w.

That's true, but...we run into that with horn loaded subs, which are so clean that they filter out harmonic distortion that warns of over-excursion. The cure is using a limiter, so that no matter how hot the amp input signal is it won't produce more voltage than the speaker can handle, either thermally or mechanically. Guitar amps routinely run with very high THD, and they use very short xmax woofers as well, so that clipping is produced by the speaker as well as the electronics. It bothers them as much as water does a duck. But they don't use tweeters, which wouldn't handle the high THD and would sound really bad as well. On that point if you've wondered why bass cab tweeters have an attrition rate that dwarfs that of woofers it's this, abnormal high frequency content that results from clipping anywhere in the signal chain, including pedals.

10 minutes ago, Dan Dare said:

 

What really "busts up woofers" is feeding them a dirty, clipped signal from an amplifier that is struggling to deliver enough power because its power supply is inadequate.

 

 

That's the Myth of Underpowering. Key word: Myth. Clipped signals can hurt tweeters by overpowering them. Woofers, never.

The lowest fundamental on a low B bass is 31Hz, but there's very little content at 31Hz. It's mainly 2nd and 3rd harmonics. The fundamental content doesn't equal the loudness of the harmonics until you get up around the open D string. Most of what we perceive as low bass is actually midbass, from 60 to 100Hz. One reason why bass can sound really bad through large PA is when a cretin at the FOH desk boosts the content below 60Hz. IME the best FOH mixers tend to be adept studio mixdown engineers and/or bass players. They'll usually high pass the bass channel strip at 60Hz, to account for the difference in how the bass sounds through bass speakers as opposed to giant PA subs.

On the range of subs they're usually run from 30 to between 80 and 100Hz.

Cabinet building without T/S specs is very much qualified guesswork. Not that you couldn't get a good result, but to do so required a lot of trial and error, a lot of time and plywood.

2 hours ago, Downunderwonder said:

1000w is a pipe dream cab rating

Agreed. It may very well handle 1000w thermal, but probably can't take more than half that mechanical. If the OP can't get enough volume with that cab it's not a matter of having more power, it's a matter of having higher sensitivity. A second cab will give that, but anything other than an identical second cab is a crapshoot at best.

They may know what they were for but the likelihood that they have specs are slim to none, and I believe that Slim just left town. They once approached me about recommending their drivers in my designs. I said sure, give me the T/S specs. They didn't have them. This was around 2004-2005, so there's no way that they'd have them for drivers twenty to thirty years older than that. I wasn't able to get full data sheets from them until 2008.

Probably a guitar driver. AFAIK those intended for bass were called G-15 100B. They date from circa 1980, so not state of the art by anyn means.

I didn't get the impression that he wanted to use it for both.

Use a combo intended for acoustic guitar. A small one is sufficient, as you only want it for personal monitor and small venue use. In larger rooms mic it to the PA. 

That should be fine.

Beaming is a product of the cone diameter. It has nothing to do with sealed versus ported, which only affects response below roughly 120Hz. The cabinet shape doesn't matter either. What the cabinet shape, specifically the baffle size, does affect is the baffle step frequency, below which the radiated wave wraps around the speaker rather than projecting forward. It begins where the baffle is one wavelength in dimension, rolling off forward response as you go lower, to a maximum of 6dB. With a  baffle dimension of 60cm, for instance, roll off starts at roughly 550Hz. It's the reason why when standing behind your cab you'll hear the lows but not the mids and highs.

I wouldn't put a lot of stock in ChatGPT. From what I've seen its accuracy rate is no more than 50%.  Artificial it may be, but intelligent not so much.

Frequency gaps aren't the issue. Uniformity of off-axis response is. The higher you go with the woofer the narrower the dispersion angle, eventually resulting in full out beaming. Most bass cabs cross over to the tweeter in the 3.5kHz to 4kHz range, which is where even a ten will beam. Crossing over at 2kHz to 2.5kHz is much better. Doing so without worry of blowing the tweeter requires a high order crossover, preferably with a 24dB/octave high pass. No manufacturer I'm aware of does so. Barefaced might, but their literature doesn't say.

Send the line level out to a power amp, or the effects return of another integrated amp.

2 hours ago, BassBunny said:

 you really need to take each driver out and test. There is a crossover of sorts in the cab which could have gone. This would then effect all 4 speakers in the way the OP has described.

Not necessarily. First, you're not looking to hear a pop or click, although you might. You're looking to see the cone(s) move. Even a 1.5v battery will do that. If they don't something isn't right. If they don't move then you pull them to test them individually. A crossover won't affect the result for woofers, as low pass filters allow the DC of a battery to pass. High pass filters on tweeters block DC, but you wouldn't see a tweeter diaphragm move anyway.

I believe they were designed for 2 ohm loads. Peavey gained a reputation for being bullet proof. One reason why is that they assumed that they'd be abused, so they were over-spec'd. They were abused for sure, but handled it well. Keep in mind that they were made long before the internet came along, and reading manuals was (and still is) considered an assault on one's manhood, so concepts of acceptable impedance loads were pretty much unknown. I had one just like that in the picture until just a year ago. I'd stopped using it only because it weighed more than I wanted to deal with anymore.  

If yours is a 15L then going to a 3015 would give better lows, mainly due to it's longer excursion. At only 3.3mm the EVM is limited to only 100w through much of its range. But don't do the 3015LF, as it is a subwoofer driver that doesn't have much in the mids. It still may be necessary to lower the tuning on the Mesa cab. Given the exact internal dimensions we can calculate what the tuning frequency is now.

TL606-606DX%20EDS.pdf

1 hour ago, Jaybeevee said:

It's a 15L in my cab. Ribbed cone as apposed to smooth.

Somebody goofed there. The 15B goes lower. The 15L goes higher, but I never found my 15B lacking for highs.

Quote

 According to TB...

Go to the horses mouth. The EDS shows a later version, loaded with the DL15X, a later iteration of the 15B.

It's more likely to have a 15B.

Ampeg speaker power ratings are conservative, so I wouldn't be concerned.