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Amp/Cab pairing problems
- Thread starter Reb26
- Start date
Mixing cabs in not the problem per se, it's the distribution of power that is the problem. A typical cab is rated for the thermal handling of its driver(s). A driver will tend to run out of excursion at about half of that thermal rating. Thus your 1x15 can use a bit over 100W before getting into trouble. If positioned on the bottom, signs of distress will be drowned out by the much more efficient (louder) 4x10.
You are lucky that with your amp set to 8Ω you didn't toast that too with a 4Ω load.
You are lucky that with your amp set to 8Ω you didn't toast that too with a 4Ω load.
Also when you say 250 watt output of my amp, do you mean the amp splits the Ws into each cab? It's a 500w amp.
Yep. With both 8 ohm cabs hooked up, each will see 1/2 of the the amp's output.
Also keep in mind that knob position has very little to do with how much power your amp puts out. I can drive an amp to full output with all knobs set to "1".
Also keep in mind that knob position has very little to do with how much power your amp puts out. I can drive an amp to full output with all knobs set to "1".
So if only half as much power is leaving each channel, how can that blow the cab?
Sorry if these questions seem a bit obvious.
Your amp only has one output channel. The two output jacks are wired parallel to each other.
One of three things is going on here:
1. You're pushing your amp beyond its 500 watt rating
2. The Ampeg can't handle anything near it's rating
3. Both dirivers you've blown were defective.
One of three things is going on here:
1. You're pushing your amp beyond its 500 watt rating
2. The Ampeg can't handle anything near it's rating
3. Both dirivers you've blown were defective.
Conventional wisdom and marketing led you down this path, and to this conclusion. The problem with the combination of those two cabs is that the 15" speaker was literally taking on FOUR TIMES as much power as any of the 10" speakers. Being that they are both 8 ohm cabs, the power was split equally between the two cabs. However, obviously, the two cabs are not identical. There is nothing about a 15" speaker , per say, that allows it to handle more power out of the box than a 10" speaker does. Also, as mentioned by another person, I would guess you are putting the 4-10 on top. This would allow the 4-10 to WAY overshadow the 15 and keep you from hearing the 15 distort, break up, and pretty much cry for help.
Fear not. I came here with the same conventional wisdom as you. I had to learn along the way as well. It happens to the best of us.
Short version = It is not Ampeg's fault, any speaker seller's fault, or the amp's fault. You didn't know so it isn't even your fault. But it is your responsibility. Getting up with the speaker guy again will do you no good. Learn the lesson and get rid of one of the cabs and replace it with a match to the one you keep.
Wattage doesn't matter AT ALL. I can blow a 100W speaker with a 25W amp. Putting that number on a speaker is useless. It in NO WAY means that you can crank your amp all the way up and the speaker is supposed to be able to handle it. FORGET about the ratings and use your EARS.
And, AGAIN, this topic has been discussed in GREAT DETAIL here. Do a search. There are literally hundreds of long threads on the subject.
1. You blew the speaker because you didn't know what you were doing.
2. That's OK because most of us thought the same things you do at some point.
3. Ratings don't matter AT ALL. You can blow pretty much any speaker with almost any amp. Watts do not equal volume. Volume does not equal power.
4. UNEQUAL DISTRIBUTION OF POWER and turning your amp up too high are what blew the speaker. Just because each CAB gets the same amount of power, that has nothing to do with how much power each INDIVIDUAL SPEAKER gets.
5. Your 15 was getting FOUR TIMES as much as your 10s. Why? Because it was getting ALL the power going to that cab, while the 4-10 cab distributed the same amount of power equally (1/4 of the power going to each) among the four speakers.
6. A 15" speaker cab getting the same amount of power as a 4-10 will not be as loud (in most cases). So you are asking the 15 to do a LOT more work than any of the 10s. Plus, being that you probably put it on the bottom, you probably couldn't hear it getting fried while you were playing.
7. Just trust those of us who have learned either from smart guys or through experience that it is a BAD IDEA for all of the reasons listed be myself and others.
I think we have (yet again) managed to beat this topic to death. Carry on.
DiabolusInMusic
Functionless Art is Merely Tolerated Vandalism
Tons of fantastic info in here, I want to add another piece to the pile since we are talking about amp output power meets cabinet handling power, my advice is to just completely ignore that at all times because it is pretty well useless. You need to listen to your cabinets, if they begin to stress stop what you are doing. You can blow a cabinet with an amp rated for far less merely by using a poor EQ control, so don't think getting a cabinet rated for a considerably higher wattage will prevent speaker damage.
Thanks, and my cabs have never sounded 'strained' to my ears.
I have also looked at other topics on this matter, I have read different articles on the internet, but I came here to talk to people about the issue more directly
Yes it IS Ampeg's fault. (Not to single them out, almost every other manufacturer is guilty.)
If a bass speaker cabinet is rated by the manufacturer to handle 220 watts, it damned well should be able to handle that amount of power, in real world situations, at the frequencies most bass players want to emphasize.
That's why I advised the OP to find out exactly what was "faulty" with the voice coil. If it's melted, that means it could not handle 220 watts thermally. If it was damaged by hitting the backplate, that means it couldn't handle 220 watts mechanically. Unless the driver was defective, or the OP was pushing his amp to its absolute limits for extended periods, it was falsely advertised as being able to handle 220 watts.
We as consumers need to start demanding that amp and speaker manufacturers give us honest, real world specs for their products.
I fully agree with you, in all my years of bassing I've never blown an amp or cab so I'm pretty surprised this has happened. All this information is helping me be more informed of the situation.
Replace the 220 watt 15" with a 500 watt 15". Then you shouldn't have a problem. You could try a Carvin 15". They are relatively inexpensive.
Cool, what people are saying here, is not just being made up.
the 115 ampeg cabinet is loaded with the Eminence legend158 is roughly 96db and the 410 is roughly 99dB
the 3dB difference is pretty much twice as loud, in other words as so many have said you dont even hear the 115 and never heard it reaching high amounts of distortion.
After 3 months of this torture the voice coil finally gave out.
the industry standard to reach band levels since the 1960's has been the 2x15
the industry standard to reach band levels since the 1980's has been the 410
once you need more extreme volume past the limits of these standards you simply double the speaker load. which will double the spl
so you would use a 4x15
or the well accepted one cab solution the 810
Most manufactures love to use thermal ratings for speakers like 300 or 400 watts, this rating is the amount of heat they can dissipate over a timeline....not how much power they can handle before reaching 10% distortion, or in simply terms speaker fart out.
The 10% distortion rating for the legend 158, or the distance the cone can move before 10% distortion is 4.8mm
the Xlim or max amount the speaker can move before mechanical damage is 9.5 mm
In roughly 4 cubic feet tuned a 44hz in the Ampeg 115 enclosure
the speaker will reach 10% distortion above 50hz at 100 watts
Below 50hz such as your low B fundamental or simply by boosting the heck out of the bass EQ at 90 watts the speaker is almost reaching mechanical damage.
Exceed this with heavy handed picking, over EQ or sharp musical peaks it would not take more than 120 to 150 watts to damage the speaker.
The thermal rating for the Legend 158 is 300 watts, and if Ampeg rates the cabinet at 220 watts, it is much more fair and honest rating than most manufactures since they knocked off 100 watts.
likewise a correct matching setup would be the standard 2x15 which would be equal to a single 410 but with extended bottom.
Attached graph shows 90 watts of power to the legend 158 which is hitting xmax above the 44hz tune frequency.
below 44hz you can already see depending on frequency the 9.5 xlim or mechanical limit is close to being reached or already being exceeded. As said go past 90 watts xlim is definately exceeded. after 3 months of this abuse, it shows the factory speaker actually can handle alot of abuse and lasted much longer than it really should of
Attachments
No, do not do this. Wattage ratings are not the end all be all. Please don't take the above advice, as it will only end poorly again. Matching cabs handle power evenly, and provide much better performance overall. Listen to the majority of experienced people here who are giving you sound advice.
