tigerstrat wrote:I really don't get the significance that seems to be placed on using three speakers. What about all the years that Jerry used 4? or 2? or 8? or 20?
ugly rumor wrote:I started to answer this post when it was first made, thinking more qualified people than I would answer. Your amplifier doesn't know how many speakers you have. All it sees is a load (impedance, resistance). So long as you do not exceed the minimum load, your amplifier will be fine. I consider going below a rated 4 ohm load to be amplifier abuse. A rated load, as has been pointed out, is usually more than the actual load; in other words, a 4 ohm rating is probably closer to 3 ohms. An amplifier rated to handle a 2 ohm load, as some are, I consider to be an exercise in planned obsolescence. 4 to 8 ohms is ideal, in my opinion. Higher than 8 ohms results in a diminishing return. Jerry and anyone else drove higher numbers of speakers using a combination of series-parallel wiring and/or slave amplifiers. Even then, especially with the wall of sound, blown speakers were a problem, primarily because of surges in voltage overcoming the resistance. Think of a water hose trying to wash off stuborn dirt, with no luck. If you place your thumb across the opening, you get a surge of power that may overcome the resistance of the dirt, and it washes away. With a speaker bank, the resistance is the speaker impedance, and a surge can blow it if it is strong enough. That's why smart giggers gig with surge protection. Who knows what's going on in some of these dives electrically, especially the ungrounded ones.
Hope that helps a little. Also, with your cabinet, there is no real reason to open the back or leave it sealed for a guitar. The frequencies of the instrument are very directional, and short enough wavelength to not matter. I am surprised that it had insulation in the cabinet. That seems to be more like a bass cabinet, which needs to absorb waves especially in a sealed cabinet, as it makes the cabinet seem larger to the speaker trying to produce long bass frequency waves against the air resistance of the out-of-phase cycle of the speaker excursion.
nabco wrote:Thank you for the info UGLY RUMOR!........... that was very clearly stated also.
You have got me thinking though,
Would it be safe to only run one speaker (8 ohms), on a Fender amp that has a 4 ohm output?
The amp has two 8 ohm speakers wired for 4 ohms right now, and i would love to make a new cab with only one speaker w/out having to buy a new 4 ohm speaker.
Am I going to kill my amp if I do this?
nabco wrote:One more thing, Is there any drawbacks to having a 10" speaker and a 12" speaker in the same cab(JBL E110 & JBL E120)? Thanks
Chuckles wrote:Thanks, indeed, UR!
Rule of thumb seems to be that with a tube power section, you don't want to go over the specified ohm rating, but with a solid state power section you shouldn't go under.
Fwiw, under gig conditions yesterday the three speaker rig sounded great, but: the 2x12 E's wired in series were noticeably not as loud as the 1 K (which makes sense given they were in series at 16ohms and rated rated for 100w more power. I'm thinking either the single K or a single E in the new cab will be the go-to rig for most dates, depending on room size and how much power I need to draw from the MosValve to be as loud as I might need to be. Just don't need anything more than that, really. The K seems much warmer than the E, as it is easier to drive a little harder. So, it'll be 250w through either the 200-rated K or the 300-rated E, or 500w through a single E. The days of hauling the 2x12 are over except in the most extreme outdoors or huge room situation (and that doesn't happen too often ).
The new cab that came with the K, btw, was most definitely designed as a bass cab I think... there are ports on the front which have been sealed with additional birch 13-ply screwed into place. Opening the back definitely took some of the bassiness out of it - plus, our drummer could hear it clearly!
ugly rumor wrote:Also, with your cabinet, there is no real reason to open the back or leave it sealed for a guitar. The frequencies of the instrument are very directional, and short enough wavelength to not matter.
Oh, yeah.. for sure they were quieter because they are rated for higher power. My question is: if the 2x12 is wired in series as a 16ohm cab and the K is at 8... do they draw different amounts of power, or are they all part of one big 5.66 ohm circuit? I'd suspect the latter, but I know squat about electronics (maybe I picked the wrong hobby! ). Anyway, the K was much louder. And - whether the K or the E - I don't see a whole lot of need to go back to a 2x12 (or 3 12's for that matter) ever again... so long as it's either a normal room or if an outdoor show it's miked and sent through the PA properly (we don't exactly have a lot of people dancing on the rails, so that front row air movement isn't all that important...).Just rewire the speakers in parallel for a 4 ohm load. Volume will be sustantially better, and you won't sound muted.
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