Timeline for Matching of the impedance for the effect pedals
Current License: CC BY-SA 4.0
17 events
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| Sep 7, 2018 at 2:02 | history | edited | Richard | CC BY-SA 4.0 |
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| Sep 1, 2017 at 14:56 | comment | added | Yorik | @user3470313: you are getting confused here (or I am). YOur question is pretty straightforward, but then in a comment you mention hooking something up between the speaker and the amp. That is the Bad Thing Todd is speaking about. There is a lot of power there and things can break and even burn. Don't confuse speaker impedance matching with lowZ-hiZ input impedance matching. | |
| Sep 1, 2017 at 14:56 | comment | added | Todd Wilcox | If you're asking if you can plug the output of the reverb and looper into the guitar input on the amp, then yes that is ok, there is nothing wrong with that. You don't even have to think about the impedances, they are correct, they shouldn't match. Matched impedances is bad for pedals, good for amp to speaker connections. If you're asking if you can connect the amp speaker output to the input of the reverb or looper, you can't because that will damage the amp, pedal, or both. Both the impedances and the power levels are wildly wrong for that kind of hookup. | |
| Sep 1, 2017 at 13:50 | comment | added | user3470313 | Why it is imposible to connect reverb and looper directly into the AMP? For reverb, OK I understand it is a modulation of the signal - thus it's better to Instal it into the FX loop to isolate from the pre-amp. But the looper (and the distortion I guess) should works normally being plugged directly to the amplifier, doesn't it? | |
| Sep 1, 2017 at 13:30 | comment | added | Todd Wilcox | @alephzero Efficiency has a specific meaning when it comes to speaker drivers. It is the measure of output SPL usually from 1 meter away while the driver is driven by 1 watt of a 1 kHz sine wave. So "more efficient" for a driver means "higher SPL measured at 1 watt and 1 meter". Trying to drive headphones from a speaker output would be very bad for at least one of the amp, the headphones, and the ears, and possibly very bad for all three. | |
| Sep 1, 2017 at 13:23 | comment | added | Todd Wilcox | This is all wrong. 1) Do not attempt to put guitar effect pedals anywhere after the speaker output of an amplifier. If you have no effects loop, you either live with that or have an effects loop professionally installed or buy a different amp. 2) Output impedances for pedals are supposed to be much lower than input impedances. They are not supposed to match. This is called "bridging" and creates the greatest voltage transfer, with very low current transfer. We want that. You can't match pedals to speaker jack. It is impossible. | |
| Sep 1, 2017 at 11:29 | comment | added | user19146 | The generally agreed "impedance standard" for line-level professional equipment is 600 ohms. Your range of numbers from 330 to 1000 are all "near enough for jazz" (or rock, heavy metal etc!) to that number. Electronic circuit design isn't done to several places of decimals, except in very specific situations! | |
| Sep 1, 2017 at 11:20 | comment | added | user19146 | The difference between the input and output impedances of one device is irrelevant. They are two completely independent things. I'm talking about the output impedance of one device, connected by a cable to the input impedance of a different device. | |
| Sep 1, 2017 at 11:19 | comment | added | user19146 | "Is it possible to connect high-impedance headphones into the 16 Ohm speaker output" That is not a good idea. On an "old-school" tube amp design, it may damage the amp simply because the output impedance is wrong (note, tube amps are different from transistor amps and effects boxes here), and if that doesn't happen, the amp can generate enough output to fry the headphones, or permanently damage your hearing. With phones the sound is generated right in your ear with close to 100% efficiency. A speaker cabinet is often less than 10% efficient, and several feet from your ears. | |
| Sep 1, 2017 at 11:08 | comment | added | user19146 | @teodozjan What do you mean by "more efficient?" High quality speakers are often less efficient at converting electrical power into sound energy than poor quality ones. The point is that the maximum power the amp can send to the speakers is V-squared / R where V is the amp's internal power supply voltage (which is fixed!) and R is the speaker impedance. That means there is a minimum speaker impedance R that you can use safely, in the sense of turning up the amp as far you like (including creating distortion) but not frying it by taking too much power from the amp. | |
| Sep 1, 2017 at 11:03 | answer | added | Laurence | timeline score: 2 | |
| Sep 1, 2017 at 10:41 | comment | added | user3470313 | it's a tube amp which also has additional output for the another 16ohm cabinet. Here I ask because the difference in in/out impedance is much bigger in case of one pedal compared to another (I specify it in the first post now).. BTW is it possible to connect high-impedance headphones into the 16 Ohm speaker output on amplifier? | |
| Sep 1, 2017 at 10:36 | history | edited | user3470313 | CC BY-SA 3.0 |
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| Sep 1, 2017 at 10:34 | comment | added | teodozjan | What about replacing speaker with more efficient one? | |
| Sep 1, 2017 at 9:33 | comment | added | user19146 | As a general rule of thumb, connecting low output impedance to high input impedance doesn't cause any problems. In any case the "mismatches" between 330Ω 680Ω and 1KΩ are not likely to be significant. Factors of 2 are important for speaker impedances, because the output impedance of a good transistor amp is 0.01 ohms or less, not 4 to 16 ohms, so "turning the amp up to 11" can easily overload the amp if the speaker impedance is too low. But "overloading" a line-level output with an impedance of a few hundred ohms won't "damage" anything, whatever you do - the power levels are too low. | |
| Sep 1, 2017 at 9:19 | review | First posts | |||
| Sep 1, 2017 at 9:45 | |||||
| Sep 1, 2017 at 9:16 | history | asked | user3470313 | CC BY-SA 3.0 |