Impeadance question

[fudgemik]

most amps give a 8 and 4 ohm stereo rating... 4 ohm being almost double in some cases but always more power....with that being said i am curious of distortion, i have been told that the higher the impeadance the less distortion.... so a pair of 8 ohm speakers will be less distortion than a pair of 4 ohm,,,,/?? is it audible or is it a number on paper?

[RGA]

I have not heard this before -- the 8 ohm speaker is easier to drive - speakers fluctuate in impedence. So even an 8 ohm speaker may have a minum to maximum range of 2ohms to 30 ohms but on average they stay around the 8 ohm range. Conversely some 4 ohm speakers may be relatively flat at 4ohms with a minumim of 3ohms and a max of 15.

[newbsterv2]

Hey fudgemik. That's actually a very good question. Depending on the amplifier and who designed it there are an infinite possibilities of how much distortion you'll have depending on the speaker/amplifier combination. Stereophile magazine will always include a series of graphs showing you exactly how much distotion an amplifier is producing into various loads including a steady 8, 4, and 2 ohm load which quite honestly don't really exist in a real speaker system. There is one measurement however that they include which simulates a "worst case scenario" speaker to test the amplifiers limits. Most well engineered integrated amplifiers under $1,000 have very respectable ferformance into 4 ohm loads across the entire audible spectrum with low levels of harmonic distortion and very small deviations in the frequency response. Actually the distortion the speaker generates is usually way higher than the amplifiers distortion!! That's why so many people spend so much on speakers because that component really has the final say in what you hear. Let us know what model of speaker and amp you have and there might possibly be some information on the net that can help us find a more exact answer to your question.



most amps give a 8 and 4 ohm stereo rating... 4 ohm being almost double in some cases but always more power....with that being said i am curious of distortion, i have been told that the higher the impeadance the less distortion.... so a pair of 8 ohm speakers will be less distortion than a pair of 4 ohm,,,,/?? is it audible or is it a number on paper?

[fudgemik]

geeeez i dont know where to start, well i built my own speakers and each consists of 2 midbass drivers, 2 titanium tweeters and 2 passive crossovers networks... they are JL audio component sets for car audio....they are 4 ohm per mid and tweet and i have 2 sets... i series wired 2 sets together to get an 8 ohm load and did that with the other 2 sets.......i hope you can follow. each passive x-over has a mid and tweet that connect to it and then an output , which is a 4 ohm rating....each of my speakers has two of these passive x-overs with the 2 mids and 2 tweets....i have an 8 ohm rating on the left and the right......i have them currently hooked up to a parasound hca-1000a 8 ohm stereo... maybe leave them 8 ohm setup and bridge mono the amp and get another amp and bridge mono the other side also since i have 8 ohm load and is proper for bridging on that amp......if i did that could one amp be slightly more or less powerfull and wouldnt be even? gosh so many questions....................... but originaly i designed them with 4 pair so i could get the 8 ohm rating i was told that would have less distortion then if i only used 2 sets and they were 4 ohm.........i guess im gonna do some trial and error and see if i can hear any difference from one set at 4 ohm or 2 sets series together at 8........

[speakeroligist_38]

Fudge be sure to understand that when you wired the JL components in series together to get them to sum to an 8ohm load you also have now changed the X-over point as well. Sometimes this can change the sound of the components and yield results that the components were not designed to produce with respect to certain frequencies. Also, most home amps are rated into 8ohm loads so if you bridge an amp it will more likely bridge to 4ohm loads. However, mono block or 1-channel amps can usually bridge down to 2 or even 1ohm loads easily because they were designed to do so. In the lower octaves distortion or noise is really not much of a concern as it is in upper midbass, mid and high frequency ranges. If you want to get another amp so that you can then bridge each side via wiring the (4) sets of JL components in parrellel then each side will bridge to a 4ohm load and as such your amps will handle that load easily. You will also get more power especially having dual power supplies and thus more headroom(gain). Hope this helps.
Phil

[pelly3s]

you wont change the crossover point due if you wire them in series before crossovers since you have two crossovers per speaker cabinet. in most cases when bridging an amp you introduce noise into the system, now that is not all cases but it does happen. the best thing to do before you go any further is find out the DC resistance of each cabinet, and also if you can measure the impedence curve and see if there is a huge difference between series and parallel. another thing when bridging an amp the amp normally will not like lower loads. some of the old yamaha peices hated anything below 8 ohms in bridge mono

[speakeroligist_38]

If you wire to sets of components speakers in series that are designed to maintain a 4 ohm load such as in sperates(tweeter, mid) then you are changing not only the impedence load (summed to 8ohms) but the X-over point as well even when wired in series. If for example, the outboard X-overs were set to cross the tweeter at say 2k and you wire in series then you are actually raising the X-over point to say 4or 5k. This is part of Ohms Law as best as I can explain it. I am no expert but have seen first hand what happens when changing impedences. I remember years ago when I hooked up some 4 ohm Boozooka Bass tubes to my brothers Pioneer receiver and it fried that receiver within 20 minutes. Why? Because the Pioneer was not designed to handle 4 ohm loads and as a result got too hot too quick. Be careful when changing X-over points too because doing so may cause one or more drivers to operate out of design paramaters. Hope this helps.
Phil

[pelly3s]

yes but if you wire two speaker cabinets together you do not change any crossover point since the wiring is done before the crossover. since from what he stated the speakers he built contain two crossovers per cabinet if you wire them together before the input of the crossover then you have no change in crossover points. your total impedence at that point is not only based on the impedence curve of the drivers but also the components that make up the crossover.

[speakeroligist_38]

HMMMMMMMMMMM...............I think I understand what you are saying. Never thought of it that way but maybe you are right. Good point about the impedence of the drivers as well as the X-over components. Like I said I am by no means an expert myself but do know Ohms Law real well. Anyways, it is good to learn in this hobby.
Phil