@Douglas Blake This loses me a bit. "You want the most powerful element feeding the less powerful element". My CD player (notice I didnt call it a transport) has a very low output which goes into my Amp and it has a really big output. Taking your most powerful object and pushing it into your weakest object in my world usually ends up with blown up weaker object. Again, this is over my head and after reading some of the comments its way over my head. The best I can relate this stuff to is, pre-amp "gain". You want your gain as high as possible so the power amp gets a full signal. I get that but there is also a limit on how much gain you want. A trick back in the day was to put your Cassette deck player on record and listen to the system through it or buy the little pre amp box through radio shack. For some reason I never like it. We just used it for recordings that were real low for some reason but it always felt like cheating. Like using an EQ and having all the slides on the gain side. Thanks for listening to me ramble. 😁
What goes over my head is why anyone would spend 💰💰💰💰💰 in audio gear. It does not compute with my brain 🧠 😀 Lots of things don’t compute with my brain. I have a lonely brain that only focuses on the need for one not the masses. I would make a terrible sheep. The herd thinks I am weird 😀😎👍
Great explanation as usual Mr. McGowan. This time I saved the vid on this topic, as I'm sure to need it in the future...say about 5 minutes from now whilst I swap amps and interconnects this morning. Thank you for your dedicated service sir.
Love these videos, Paul! Small piece of constructive feedback: I think that, for more complex topics like this, you could be more effective using a simple visual aid like a whiteboard. Thanks for all you do!!
I understood the rule of thumb is a 10:1 difference between source and amp to ensure clean signal without attenuation/distortion. One practical example is an amp with a 100k input impedance can be run without a preamp. I use autoformers as a linestage attenuator which are very good if you have good matching between source and amp.
i got it...but what is the problem in sound when, lets say the dac got a to high output impedence. i wanna buy a denafrips venus 2 12th and its got 1250kohm at xlr. my pre amp got 40kohm. Accuphase c2120. this should be also fine or am i wrong? i dont get what can happen
It is probably too late to be useful but... The output impedance of this DAC is 1250 Ohms, not kOhms. The input is 40 kOhms - that is 40000 Ohms. So lower impedance can drive higher impedance easily with little attenuation. Impedance matching in audio gear is really a non-topic because the designers of equipment make the output impedances low and the input impedances high - why wouldn't they? The output impedance is most likely a resistor added to ensure amplifier stability when driving a cable with high capacitance. I am an electronic engineer and I'm happy to answer any questions but I am not an audiophile so don't ask me about the polarized speaker wires or single crystal copper conductors... :)
The standard seems to be 47k for input and 200 ohms for output on line level equipment. Paul is correct on those ranges. Power amps, speakers and headphone get more complicated since your dealing with a voltage gain stage followed by a current gain stage and a power transducer.
interesting. but what do you think is the reason of why my cheap equipment sounds worst, but it only happens if i switch source to dvd player's line out. it has too much bass, sounds distorted, my amp says it has an input impedance of 150k ohms (cheap chinese amp). Why is this?? is this the cause of having poor impedance matching or it's just the line out of my dvd player having a bad circuit design?
........except if you need to go a long distance. If the distance is long enough, the propagation delay and impedance mismatch reflections are generated and cause echos and distortion. This is usually a line level, and balanced lines. Z = 600 Ohms. I think the distance is in the miles, or 10s of miles.
hmm. i remember once in the past millenium, i had a couple of dynaudio contour ll speakers. they had the option to be driven by an impedance mathing network, including a bnc terminated speaker cable. the sound was amazing. an expanded soundstage, was the most noticable result. so, i dont know. maybe a smith chart is very relevant in hifi too...
Maximize voltage drop across the inputs and minimize voltage drop at the outputs. In other words reduce load on the source and deliver Max power into the load.
So basically what Paul is getting at is that low impedance drives current. You don't want your source having to do the work of driving the current that you're pre-amplifier would have to drive an amplifier with hence the high impedance between the two. A lot of sources can drive and amplifier nowadays pretty well. But it is still nice to have a clean pre-amplifier between the two. There are some gains to be had there and surprisingly it's not just gain :)
What about a 2Vrms rca source with a 10k ohm passive pot and a 20k input impedance amp, qould it be enough to drive it? Worst-case pot impedance would be about 2.5k, so 20:2.5 = 8:1 impedance ratio, right?
Distortion that is audible is added. I speak from experience. I was chasing it until I figured out this was the issue. I tried to split a preamp signal causing this issue
Preamplifiers and source devices are voltage amplifying devices and they can't feed the current required to a low input impedance device. The result, is lower signal level (lower volume), added distortion and frequency response problems (lose of bass and tremble) . As the ratio of in/out impedance comes close to 1 (or worse) the effects are more and more noticeable.
What you are saying is correct for voltage transfers as is typical in low level sources to gain stages (preamp). And pre to power amp And for solid state amp outputs where lowest internal PS loss is needed. But you mention tube amps. In the typical output transform based designs POWER transfer is more important than either just voltage or current and power transfer is at it's maximum when source and load are the same impedance. Power transfer is also more important in RF transmitters to the antenna. Simple math will show you the power transfer function.
@Douglas Blake Use use RCA cable to your speakers? And VLF radio waves go down to 3Khz. No wonder you are so clueless! But thanks for the attempted attack!
The power amp / speaker thing is incorrect. The speaker impedance should match the true source impedance of the amplifier. Anything else will just result in reduced output power. No amplifier is specified with an output impedance in milliohms. It will be specified in ohms with a damping factor, e.g. 100W with DF of 100. The actual output impedance is the voltage output divided by the current. The output impedance as measured with a small signal impedance meter may well read in milliohms as the output impedance is artificially lowered by the application of negative feedback and this value can be calculated from the damping factor. This lowered impedance only holds true within the capabilities of the output transistors and makes no difference to the ‘real’ source impedance. If the ‘real’ impedance of (say) a 200W amp designed for an 8 ohm speaker was really 10 milliohms, it would be possible to connect it to a 10 milliohm speaker and get an output of 160KW with an output current of 4000A, which is clearly not going to happen.
Agree with you. His explanation only holds true for connecting from preamp to power amp. For passive devices like speaker, the impedence need to match the power amp for maximum power transfer.
Does this apply to loudspeakers connected to amplifiers as well and if so, wouldn't an 8 ohm loudspeaker nearly always be a better choice compared to a 4 ohm one?
@Douglas Blake Thanks for spotting my incorrect answer. I'll blame it on brain fade. It should actually read "Maximum power transfer occurs when the load impedance is the complex conjugate of the source impedance."
Does your amp have a switch on the back for 4 or 8 ohms? If so in a lot of cases the 4 ohm side just cuts the signal some so the amp can handle it. Audioholics did a video on it I just can't find at the moment.
This question is not really answerable. Speakers have an impedance - they do not "accept" one. You can measure it with a multimeter on Ohms. The other commenter is correct - usually any switch on the amp just reduces the signal for the 4 Ohm setting to maintain the power output but not exceed it. I'd suggest you check the speakers - usually there is a ratings plate with the impedance and the maximum power - and set the switch to the appropriate setting. :)
Is this why some Audiophiles and Audiophile newcomers have trouble with component management matching..?? They failed Audiophile 101..? I use an old saying. “Keep it simple stupid” Less headaches.
@Douglas Blake You mean they are always yelling the sky is falling and it’s the end of the World..?😀 A 10K power cord will save the World. 😀 Along with 20k for a complete overhaul the House electrical system.😀 To play a record on a record player..😳
@Douglas Blake You see it goes like this every day with Audiophiles. My speakers are not working the way they should and what I was told beforehand. 😂😂😂😂😂😂😂😂😂 I need 4K in room treatment to try to make my speakers sound good. 😂😂😂😂😂😂😂😂😂😂 I need to hook into a Nuclear Power Plant to get my speakers to sound good. 😂😂😂😂😂😂😂😂 I don’t think my speakers are giving me all the bits I am supposed to get. 😂😂😂😂😂😂 😂😂
The so-called audio engineer left out a verry important part. How power into a load effects the volume of loudspeakers. And that so called audio engineer did the same thing when attempting to explain loudspeaker impedance. Power into different loads does not give you the same volume and the change is not even linear. This is actually what you need to know for impedance matching between an amp and loudspeakers. 100 watts into an 8 ohm load, 200 watts into a 4 ohm load and 400 watts into a 2 ohm load are all equally load. And remember, a 4 ohm nominal impedance loudspeaker will probably go below 3 ohms in some frequencies because the load of a loudspeaker is a little different for each frequency.
Hey Andrew - ease up a bit! "100 watts into an 8 ohm load, 200 watts into a 4 ohm load and 400 watts into a 2 ohm load are all equally load." Is that supposed to say "loud" - otherwise it makes no sense. If it is supposed to say "loud" then it is incorrect. The power is what creates the acoustic output from the speaker. The different impedances are created by different numbers of turns in the voice coil... More turns - less current, more voltage, higher impedance. Between an amp and a speaker you just need to ensure that neither will overheat. Too heavy a load (low impedance) on the amp will reduce its efficiency and create too much heat. Too high an output power from an amplifier (into a particular impedance) may damage the speaker. Most amplifiers have power output ratings for various speaker impedances. If the amplifier is 100 W into 8 Ohms then a 200 W 8 Ohm speaker will be ok but a 50 W 8 Ohm speaker may get toasted. If an amplifier is rated for 100 W into 8 Ohms but has no 4 Ohm rating - don't connect it to 4 Ohm speakers. 16 Ohm speakers will be fine but you will not get the 100 W before you start to clip, probably only about 50 W. P=V^2/R, double R and you halve P... I have the benefit of a degree in electronic engineering and have been designing products for 40+ years. I thought the "so-called audio engineer" did a good job!
Paul, to me, all of your gear looks like bland computers. It is all so sterile and unattractive in terms of design. It looks more suitable for a lab than a nicely decorated den or living room. Others, of course, may differ. Art is in the eye of the beholder.
Gotta laugh at this guy's passive aggressiveness in butchering the pronunciation of Framingham. For those who don't know, Framingham is home to Bose, which is a company this guy absolutely loathes.
