Bill Fitzmaurice

Fuzz can kill tweeters, octavers can kill woofers. If you must use an octaver, and I would not, you should have the EQ on your amp pulled down below 40Hz, otherwise the drivers can be damaged by over-excursion.

[quote name='alexclaber' timestamp='1371735588' post='2117519'] Biamping is not going to be beneficial with those cabs. The 15" may go lower than the 4x10" but the 4x10" will move more air and so be better at the lows. The 4x10" probably goes higher than the 15" but has worse dispersion through the mids so will be harder to hear around the room. So neither cab is a specialist at either lows, mids or highs. [/quote]+1. One bi-amps when they have two cabs with distinctly different frequency band widths. Mesas, and for that matter virtually all electric bass cabs, don't.

[quote name='Mr. Foxen' timestamp='1371723848' post='2117311'] Trannies for valve amps don't cost any more to have made than ones for SS. Its still iron and wire, [/quote]Ture, but valve amps need an output transformer as well, SS do not. Valves themselves are very expensive as their manufacture is fraught with environmental issues, high labor cost, and very limited usage/demand.

[quote name='MoJo' timestamp='1371677033' post='2116964'] Why are all valve amps so expensive? [/quote]Because the musical instrument industry is the only one that still uses them. Price is inversely proportional to production quantity.

[quote name='Mr. Foxen' timestamp='1371563394' post='2115556'] How do you predict then? Using phase charts? [/quote]That would be part of the method. But you can't even get SPL charts for cabs, let alone phase charts, so even if you knew how to use them to predict the combined response the necessary tools just aren't available.

[quote name='Chris Horton' timestamp='1371410346' post='2113570'] I do run the 410 & 210 together for bigger gigs but when I do , it feels like the 210 cab is struggling compared to the 410 if that makes sence. [/quote]It does, because both are receiving the same power. For them to work well together the impedance of the 410 would have to be half that of the 210.

[quote name='JTUK' timestamp='1371392503' post='2113252'] I've never seen any value in a 15" cab [/quote]To put it in a historical perspective, once upon a time fifteen inch drivers tended to be better suited to low frequency applications, while twelves and tens were better suited for higher frequencies. Until roughly 1975 for the most part there was no such thing as guitar versus bass drivers, there were only musical instrument drivers, most of them designed for guitar. Some fifteens were designed for organ and PA, and worked better with bass than guitar tens and twelves. The original 1969 SVT was loaded with guitar tens, that's why they needed sixteen of them to handle the 300w head. Taken in that context, circa 1950-1975 there was some benefit to mixing cabs. That benefit went away with the introduction of true electric bass tens and twelves.

[quote name='Mr. Foxen' timestamp='1371384013' post='2113139'] Mixing cabs is a bad plan. The reason it is a bad plan is that the sound of the combination is totally unpredictable, so as soon as you plan on mixing the cab with unspecific different cabs, you can't get any useful suggestions, because nobody can know how they will pair up, the sound isn't a combination of the souds of the two, its another sound again. Do you like the sound of the 10s you have but need louder? Get more the same. If you don't like the sound of them, get rid and get somehting you do like the sound of, then add more the same until loud enough. [/quote]+1. In addition, the usual reason given for adding a fifteen is to get lower extension. The fact of the matter is that the average fifteen loaded cab goes no lower than the average ten loaded cab. As for output capability, the average 1x15 has less output capacity than the average 4x10. Advertisements mixing 1x15 and 4x10 are ubiquitous, as is the use of that by many endorsers. Why? Ads are intended to sell product, as is supplying endorsers with what the company wants to sell. As to what companies want to sell, that's highly driven by what you want to buy. If you think that 1x15/4x10 is a good combination no company is going to try to talk you out of it. They'll give you what you want and take your money, thank you. The more you know about how speakers work, the less likely you'll want to mix cabs. As for what endorsers use, don't assume that just because they're great players that they know any more about speakers than you do. Bottom line, they use what they're paid to use.

[quote name='krispn' timestamp='1371274527' post='2111953'] was wondering if I should be looking for a head which can give the cab more oompf at the rated 8ohm. [/quote]That depends on the drivers in the cab. Some top of the line twelves will take 400w before reaching their excursion limit, but most won't. The average twelve with 5mm xmax reaches its maximum low frequency output capability at no more than 150w, no matter what the voice coil thermal rating may be.

[quote name='malcolm.mcintyre' timestamp='1371155047' post='2110714'] I believe they need a lot of amplifier damping, like a big powerful Crown. [/quote]No moreso than any other cab. They were developed by Voigt/Bailey/Bradbury in the days of valves.

[quote name='JTUK' timestamp='1371138010' post='2110387'] That would be a warning sign to me, tbh.... but as for config, I wouldn't go up against a gtr212 with a bass 210. [/quote]+1. With a one octave drop in frequency range power/driver displacement demands quadruple. A 2x12 guitar versus 2x10 bass cab is a severe mismatch, like a heavyweight taking on a lightweight. Care to guess which one will lose? [quote]They mainly do Guitar Cabs so anything about speaker reccomendations are related to guitars[/quote]With guitar you can literally stick a driver into a box and it will work well, with no engineering whatsoever. That's the complete opposite of what's required for a good bass cab.

[quote name='Mr. Foxen' timestamp='1371049855' post='2109134'] With same power, the PS cab is going to be loads quieter, since you are feeding power to two speaker, but only one of them is moving air. Plus its a smaller speaker. [/quote]+1. Output is determined by driver displacement. The OBC115 has 343cc, the SP212 has 255cc. If you want a lot of output from a small package the barefaced Big Baby has 496cc.

[quote name='helmn' timestamp='1370974349' post='2108193'] I am probably going to line rather than stuff the TL [/quote]That's not a choice you can make arbitrarily. You must measure the response and/or the impedance and use as much damping as is required to suppress the harmonics without over damping. If you don't have the required gear to do so there's no way to get it right.

[quote name='Beer of the Bass' timestamp='1370956913' post='2107906'] I've seen it mentioned that some of the existing cabs labelled as transmission lines (like Euphonic Audio) are too short to be true transmission lines and behave more like ported cabs. What does the port stuffing do in these cabs? Subjectively, the cabs "work" but it would be interesting to know what's going on with this design. [/quote]A true 1/4 wavelength long TL is a resonant pipe. The primary resonance at the 1/4 wavelength frequency is beneficial, being added to the driver front wave radiation. There are also higher frequency resonances at the harmonics of the 1/4 wavelength frequency, and those create undesireable response peaks and dips. The line should be stuffed with sufficient damping to remove the harmonic resonances while leaving the fundamental resonance unaffected. As for the EA, its operation would be identified by an impedance sweep, but I've never seen one.

A useful TL would have to be at least 2 meters long, while low Qes/Qts pro-sound drivers don't work well in TLs. All in all they're just not a good alignment for electric bass, as they don't work any better than much smaller and easier to construct bass reflex.

When the guitar player turned up that should have affected both the mains and monitors, so the engineer should have noticed it. You should have just asked him to turn that monitor feed down between songs. Turning up your amp may or may not affect the volume in the PA, depending how the DI works in your amp. Some are pre-master, some are post-master, some are switchable. Your owners manual will say.

[quote name='The Dark Lord' timestamp='1370808635' post='2105898'] I'm thinking of replacing our PA for our three-piece band (guitar, bass and drums) with a Bose L1 Model 2 with a B1 bass module with a T1 ToneMatch module. From what I can assess, it would be fine in a band situation for up to 200 people ..... which is the most we ever do. [/quote]A keyboard player friend of mine has an L1 with two bass modules, and when he does his single act it works OK for his keys and vocals. When he plays with my R&B band only his keys go through it, his vocals go through my PA, and we generally play 200 seat rooms. For singles and acoustic acts they're OK, though grossly over priced. For a real band, forget about it.

[quote name='PaulKing' timestamp='1370783106' post='2105436'] Any amp/electronic experts able to answer me this? I use a Markbass CMD121P combo. I just replaced the internal piezo-tweeter with a better mini-horn. Is there any risk to my amp from this? [/quote]There is, as piezos generally do not use crossovers, and when they do they do not have the same topology as those used by dynamic drivers. You can't just swap a dynamic tweeter for a piezo, and the crossover for a dynamic tweeter must be specifically configured for it. You're running the risk of blowing the tweeter and possibly the amp as well.

[quote name='graham1945' timestamp='1368869585' post='2082400'] I read somewhere that you should never run a valve amp without speakers, however, does the same apply to all transistor and the new class D amps? In other words could I use a class D amp as a preamp only without connecting it to speakers? [/quote]Valves need a load, SS doesn't. Most valve amps short the output just in case you forget to plug speakers in, to prevent damage.

[quote name='aende' timestamp='1370614109' post='2103493'] So, I called Ashdown, there is nothing they can do as they have no more LG parts or modules in stock. [/quote]Try Alto, that's where Ashdown got them from.

[quote name='Lozz196' timestamp='1370257014' post='2098084'] No problems as long as: 1. Each speaker cone is rated 250 watts or more - and just having looked it seems the Eminence Beta is. [/quote]From the standpoint of not cooking the voice coils, true. But with only 3mm xmax they reach their mechanical limit in the lows at about 50 watts each, so any hint of farting out should be well heeded.

Make sure the fault is the amp and not the bass.

[quote name='Beer of the Bass' timestamp='1370078726' post='2096233'] As an aside, does anyone have an idea how much the output of a typical valve amp is reduced when running into an impedance mismatch? [/quote]Tubes have constant power output because the tubes don't see the speaker as the load impedance, they see the primary winding of the output transformer.

[quote name='dangoose' timestamp='1370038929' post='2096017'] I have 72 Bassman 50 silverface and it works well with 4ohm loads. I wouldn't run it into any load less than 4 ohms, the output transformer was designed for a 4ohm total(its not switchable). [/quote]The original Bassman cab was 4 ohms, and the head was designed to use two of them. Not knowing any better we used to run Bassman, Bandmaster and Showman heads into four 4 ohm cabs with no ill effect. We ran them into 8 ohm cabs also, no problem. As is the case with all tube amps they're happy with low impedance loads but not high impedance, so I'd not use one with a 16 ohm cab.

[quote name='jimcroisdale' timestamp='1369934528' post='2094692'] One thing I thought that might work would be to get hold of another identical cab and use them as PA. Does this sound feasible? [/quote]No. Most bass cabs don't have the flat frequency response nor wide dispersion required for PA. Some are OK, mainly 3 ways, but this isn't one of them.