2. amps-preamps
  3. 1132627794

Major help needed in Input and output impeadance..

Okay, so if you have a 10 kohm or 10,000 ohm input in amplifier terms, what are the parameters for the output on the preamp? I see anything ranging from 50 ohm to 600 ohm in preamps outputs. And see many amplifiers from 10 kohm , 20 kohm, 30 kohm, 50 kohm etc... I know there is a rule of thumb but what is weird Is most of the manufactures I see building amps with 10 kohm up to like 50 kohm are building preamps with only about 50 ohm outputs.... nothing near what some other manufactures use between 220 ohm to about 750 ohm.

I will have a 600 ohm out pre soon and my amps are only 10,000 ohm inputs. so what does this mean? it almost seems that the 600 ohm may not be compatible in looking at the matching most manufactures use as they are all much lower output impeadance in general vs. my preamp, so what happens, I get less gain, more noise, what can be a problem if you have mismatched impeadances between these two components? Or is all this irrelevant and I just need to get the preamp and listen and not worry about it? But I swear I read something about this topic at some time and really want to make sure I know what I am doing.

Thanks, Ps. in my post I did use K- for increments of 1000 if anybody got confused when I wrote out the whole number and then started using the abbreviation with 'K'
matrix

Showing 8 responses by matrix

matrix OP
305 posts
 
Hmm well the amp has no spec. on the input gain shown, but the pre amp is from 2 volt to 10 volt output, so if I have a 2 volt cd player I would guess I get 2 volt out of the pre, maximum out would be 10 volt, so in my case I do have a 4 volt out CD player so I assume it will pass 4 volt down to the amp... Now I would guess the only way to drive the pre to its full 10 volt out would be something like a cd player with 4 volt into an equalizer or something that boosts the signal another 6 volts and then you would be at max, so I am not worried about the preamp being overdriven really cause no source I own or even seen sold would put out that kinda voltage in general maybe some phono stage?, but it does not have the gain spec. shown on the preamps papers either, but I would guess it is 20 db gain stage.

It does have the signal noise ratio of 112db which is pretty good from what I understand, but I dont know this spec. tells us anything, also it is capable freq. range of 10hz to 200,000 hz, so its a high end piece, not the standard 20hz to 20,000 hz most are specked at, again this all may mean nothing?
matrix OP
305 posts
 
Gmood1, Thanks I do understand the standard is 2 volt, but I can assure that my Wadia CD player in fact puts out the pro audio standard voltage of 4 volt at the RCA's As well as XLR, as why it much more full and powerful sounding than most players. As for speaker frequency, Mine Go 16hz to 25,000hz, no problem there either, whether it can be proven we hear or feel it is another story, but I guess the frequency's exist thats why they have products built beyond the call of duty. Not sure why but all the top manufactures flagship Preamps are in the 10hz or even 5hz up to 100 khz, or 200 khz, is it necessary? , probably not but I guess these are the flagship specs. cause yes the run of the mill and even fairly high end pieces only claim 20 hz to 20 khz... Who knows, but thanks I will see what this preamp does I was just concerned of the impeadance match, but it should be okay.
matrix OP
305 posts
 
I know what your saying, I just was reiteratting the fact for some reason the "Flagship" pieces seem to spec. frequency out of this world, whether it will help anything is another question. Actually thats funny I did just have the Wadia modded, with a new clock all caps replaced with Rubycon Cl/Cz (supposedly better than Blackgates, but Rubycon makes the blackgates so I don't know), WBT next Gen jacks, Silver Rectifier bridges etc... and they told me the output stage in the wadia is about as simple as it gets with one Opamp and thats it, they believe it is very good analog out stage already, but could get the silver transformers put in but we are talking a 1000.00 mod, and I am skepticle going that far to be honest.
Thanks for the tips, I hope the Preamp works out Too!
matrix OP
305 posts
 
Jeffreybehr, I do have a Tube Hybrid preamp, But you lost me a little... So I should be capable of full output with 600 ohm preout's, and 10,000 ohm inputs on the amp? Sorry you used a spec double that as an example and got a little confusing, thanks
matrix OP
305 posts
 
Jeffreybehr, What I got from what you are saying is that my ratio would be 1:17 ? Which seems that I will not get full output then, but maybe I am not getting it thanks again.
matrix OP
305 posts
 
I got you, just need to experiment, use the best equipment possible to get the job done, thanks guys.
matrix OP
305 posts
 
They are 6 ft... could be possibly shortened a bit maybe to 4 ft if necessary, but they go to mono blocks so got lower margin for adjustment for the distance.
matrix OP
305 posts
 
Okay guys, heres what I found

Balanced audio tech in fact builds a preamp with 750 ohm outputs, it states on there chart it is recommended not to go below 10,000 kohm amp... they have models capable of even driving some rediculosly designed amps with 3,000 ohm inputs but need to use their Optional "Bat Pak"

I also called McCormack Audio, I do not own their equipment, however they have there Flagship amplifier the DNA-500 at 10,000 ohm input... It is in the words of their engineers that Anything over 10 times your preamp impeadance is perfectly fine, So if it is 600 ohm its good to even drive a 6,000 ohm impeadance Amplifier, which is rare to find, but they even went on to say the most Weird and hard to drive amp they have seen to date(and he could not remember the name) was at 2,000 ohm input and they believe the only preamps they would have available to drive it is from their sister company Conrad Johnson with something in the 50 ohm output range...

So from what I found is 1:20 ratio is not the rule it is 1:10 I guess, which now thinking back I have heard multiples of 10 were always the rule? So I guess we are okay, Thanks guys it was good info.
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