Bill Fitzmaurice

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.

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.

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

What I can't do with four strings doesn't need to be done. 😉

True, but that was 30 odd years ago, when very few mainstream manufacturers used premium drivers. JBL, Altec and Gauss were in the same league, hardly anyone used them. EV and JBL both made cabs back in the 70s, perhaps into the 80s, which were far superior to Fender, Ampeg and most others. They never sold well, so they were eventually discontinued. That's because back in the day you never bought amps and cabs as separates, you bought them as a matched set. Mesa was one of very few that sold an amp and cab set loaded with premium drivers. Sunn was another. The TL606 was good in its day, but it was optimal with 55Hz tuning, which gave a 60Hz F3 and 45Hz F10. The step down option lowered the Fb to 40Hz, which lowered F10 to 40Hz but it raised F3 to 70Hz, so it didn't work all that well.

Low end response is 1/3 driver, 2/3 enclosure. If the enclosure won't support deep bottom no driver will give it. BTW, the Kappalite 3015 response isn't much different from the 15B. The 15L is weaker in the lows, being optimized for guitar.

Usually hiss is created early in the signal chain, so gain amplifies it, making it worse as the gain is increased. If it's there no matter where the gain is set then it's taking place further along the signal chain. That could indicate a fault in the amp, perhaps something as simple as a broken PC board trace or a cold solder joint on a component. That's something that could have occurred when it was shipped. I'd call around to see if a nearby store has one that you could compare yours to. That way you'd know if yours is within spec.

A compression driver is a type of tweeter. Back in the early days of SS they were much noisier than tubes, but I'm talking 50 years ago. Tubes aren't inherently noisy. I wouldn't say Ampeg is limited at all. That's because it's not an issue. Quite right. Other steps for minimum noise is to turn down the gain, turn up the master, and turn off the ultra high switch.

The Bravo 112 cabinet volume is perhaps half that required for good results with electric bass.

It may not, the loop could be on the back side of the input stage but before the gain control. The manual should say.

The mass of the steel of the frame is dwarfed in comparison to that of the top and bottom plates, so it's a minor concern.

Cast aluminum baskets are used for two reasons. With heavy ceramic magnets it's to be stiff enough so that the frame doesn't flex. With neo magnets it's to act as a heat sink. Steel is OK with lighter weight ceramic magnets, and with lower power neo magnet drivers that don't require much heat sinking. Eminence uses steel for their 150w Basslite series, cast aluminum for the 250w and higher Delta Lite and Kappa Lite. Where frame stiffness is concerned there are two requirements for very high sensitivity. One is a high flux magnet, the other is a tight magnetic gap. If the magnet weight causes the frame to flex it can cause voice coil rub with a tight gap. That was a problem with the 1968 Electro-Voice SRO 15, later re-badged as the first generation EVM. It had a cast aluminum frame, but with only four spokes, so it would flex under the weight of the 16 pound magnet structure. The second generation EVM cured that by going to an eight spoke frame.