Yingtonggao's problem was too much system gain with his 104db speakers. As the low gain Cary poweramps seems to have now fixed.
The cheapest way I suggested in one of my first posts a removal of gain by either going direct or the use of a passive, mine or anyones, and that colouration may also be reduced, and that Nelson Pass also recommends this. *Below is is quote again*
It was just couple of others here that started the passive vs active debate.
*A Quote from the master Nelson Pass
We’ve got lots of gain in our electronics. More gain than some of us need or want. At least 10 db more.
Think of it this way: If you are running your volume control down around 9 o’clock, you are actually throwing away signal level so that a subsequent gain stage can make it back up.Routinely DIYers opt to make themselves a “passive preamp” - just an input selector and a volume control.
What could be better? Hardly any noise or distortion added by these simple passive parts. No feedback, no worrying about what type of capacitors – just musical perfection.
And yet there are guys out there who don’t care for the result. “It sucks the life out of the music”, is a commonly heard refrain (really - I’m being serious here!). Maybe they are reacting psychologically to the need to turn the volume control up compared to an active preamp.*
Cheers George
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It is a banaid fix because his AMR has to drive the input of a preamp through the same interconnects and pre amp inputs are usually 47kohm (industrie standard), his FL100 is acually higher and easier to drive at 57kohm through the same interconnect and 1 pair less as well.
And gain doesn't even come into it as he has an abundance. and as a bonus it's all direct coupled, no "masking" capacitors in the signal path as it would be with many preamps.
A preamp in this case in the path can only add colouration/distortions that some may like because it's masking a problem elsewhere.
Like I said Nelson Pass's quote says it all, to contradict it is almost blasphemous. read again carefully.
Cheers George
A Quote from the master Nelson Pass
We’ve got lots of gain in our electronics. More gain than some of us need or want. At least 10 db more.
Think of it this way: If you are running your volume control down around 9 o’clock, you are actually throwing away signal level so that a subsequent gain stage can make it back up.
Routinely DIYers opt to make themselves a “passive preamp” - just an input selector and a volume control.
What could be better? Hardly any noise or distortion added by these simple passive parts. No feedback, no worrying about what type of capacitors – just musical perfection.
And yet there are guys out there who don’t care for the result. “It sucks the life out of the music”, is a commonly heard refrain (really - I’m being serious here!). Maybe they are reacting psychologically to the need to turn the volume control up compared to an active preamp.
Cheers George |
Yingtonggao, just read this quote from Nelson Pass, I think we could all aggree that we all here with our combind wisdom pale into insignificance compared to him. Remember your FL100 takes 1.4v input to clip. Your AMR DP777 gives out more than 2v and you have 104dB sensitive speakers.
A Quote from the master Nelson Pass
We’ve got lots of gain in our electronics. More gain than some of us need or want. At least 10 db more.
Think of it this way: If you are running your volume control down around 9 o’clock, you are actually throwing away signal level so that a subsequent gain stage can make it back up.Routinely DIYers opt to make themselves a “passive preamp” - just an input selector and a volume control.
What could be better? Hardly any noise or distortion added by these simple passive parts. No feedback, no worrying about what type of capacitors – just musical perfection.
And yet there are guys out there who don’t care for the result. “It sucks the life out of the music”, is a commonly heard refrain (really - I’m being serious here!). Maybe they are reacting psychologically to the need to turn the volume control up compared to an active preamp.
Cheers George |
I also know where your coming from, and I'm only
condescending to those who deserve it. We’ll just agree to disagree.
Cheers George |
Ground loops are most likely to present 50/60hz "LF Hum", a BUZZ as the OP says he has indicates higher frequency content, this could be rectifier noise, but from 4 separate preamps tube and SS this is not likely.
If the "buzz" raises and lowers with volume control posistion on the 4 preamps, would mean that is eminating from the source. But because the source is dead quite when it is direct to the amp, the source can be ruled out.
If it is a hum and not a buzz you could try this:
If all 4 preamps have grounded mains cable you could try to disconect the earth wire and see if that makes a difference, or if they have no earth wire on the mains try to give it one to the chassis.
Cheers George |
Sorry Roscoeiii, you need to read Nelson Pass's quote more carefully.
"just an input selector and a volume control.Hardly any noise or distortion added by these simple passive parts"
His B1 buffer is active
"no worrying about what type of capacitors – just musical perfection."
His B1 buffer is also capacitor coupled.
Cheers George
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"being more ripe, full-bodied, and solid. I've bought and sold hundreds on audiogon."
All preamps sound different,Yingtonggao this is why you've bought hundreds?? they do not all sound like straight wire with gain (uncoloured) otherwise they would all sound the same and there would have been no reason for you to buy hundreds.
As they are all coloured in some way and not true to the sound of the source you are looking to find the colouration you prefer. Just these two statements of yours have basically said to me just that.
Cheers George |
Yingtonggao looks like high system gain may have be your problem with the other setup.
This is what Stereophile said about the measurements on the Carys, looks like they have very low gain. Which is what's needed for a very efficent horn system.
"Input impedance was an easy 150k ohms in parallel with around 100 picofarads.
The amplifier needed a fair input voltage despite its modest output power"
With their very high input impedance of 150kohms they are also begging to have the DP-777 directly into them.
Cheers George |
He hasn't said he's tried this new amp (Cary) direct yet.
Cheers George |
He has it all there, and won't cost him a cent to try it. He may even be in for a bigger/better surprise.
After all it will be the most transparent/dynamic way of being true to the sound of the source there is going direct, as it is also a prefect match as well.
Cheers George |
Ok you tried to give all 4 preamps a earth with no joy, but you have not said if the mains lead on them is earthed?, if so disconect it, if this still is not a fix, "luckily you can still enjoy music running source-direct." which in your case is a good impedance match and you still have an abundace of gain.
Cheers George |
Yes you are right Al, my bad, I was including the phono, but up to 20db for the line level is not unheard of.
eg:
The CAT line stage: 15.0dB of gain set to Low and 25.8dB set to High.
Balanced Audio Technology line preamplifier gain was slightly higher than the published specification, at 18.7dB
It only takes the OP's power amp 1.4v to clip and he has over 2v from the dac so he does not need and more gain from the output stage of a preamp which in 99.9% of cases comes after the volume pot.
Cheers George |
Worth a try if it doesn't cost him even more money and time to rid the noise.
I believe he maybe just hearing the noise from too much amplification with 104db speakers and when he OMITS the active pre (and he has tried 4 different ones solid state and tube) he is reducing his overhaul system gain by maybe 40db or more, and this also equates to the reduction of the active component noise as well when he goes direct, remembering every 6db of added gain is double the voltage.
Cheers George |
He has way too much system gain, and with speakers that are 104db! He shouldn't have to use an isolation transformer if that would work at all with the problem he has.
Cheers George |
He has tried all that and more.
Quote from the OP:
whenever I insert an analog preamp. If I run my DAC (AMR DP-777) directly into power amp, the noise disappears. I have tried 4 different preamps (tube and SS), 3 different amps, a bunch of RCA and XLR interconnects, the problem persists. I have tried dedicated power line and two power conditioners (with Multi-wave options) and various high-quality power cords, so far nothing works, and I am forced to run DAC-direct into power amp.
Cheers George
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My whole argument is for the OP to go direct with his DP777 dac and use the inbuilt passive in it.
And yes if you want to drive 30ft of interconnect an active is the way to go.
My comments on voodoo are just that some believe that an active preamp can actually add real musical information that the source isn't providing, this shatters me that some can believe this.
Cheers George |
Charles1dad Quote:"Anything inserted into an audio system signal path will make its presence known."
That's right, one of the best open/transparent sounds lately I have heard was from a old Musical Fidelity A3/24 dac that has such a beefy output stage (standard) that can give 6watts!!!, (modified output resistor from 47ohm to 1ohm)
This dac was directly attached to a pair of highend 108db horns from Italy (no power amps, no preamps), directly from the dacs output rca's to the speaker terminals.
The more active junk in the signal path the worse/electronic the sound becomes.
Cheers George |
Like I keep saying.
"By all means you can change the sound to your liking with a active preamp of your choice, this is why ALL ACTIVE PREAMPS SOUND DIFFERENT, as they are not a strait wire with gain"
But if you want to hear the source as it is, go direct this is, a straight wire with no gain.
Cheers George |
Also just to let you know that Nelson Pass originally designed the B1 buffer back in May 2008
http://www.diyaudio.com/forums/analog-line-level/80194-lightspeed-attenuator-new-passive-preamp-137.html#post1521766
to be on the output of the Lightspeed Attenuator so it could then drive low input impedance amps of 20kohms or less that some of his amps have that people want to use the Lightspeed with.
You can read all about it on the Lightspeed thread on diyaudio.
After that he released it in diy form with a passive pot for diyer's who wanted to use just a potentiometer as the volume control.
Cheers George |
YingtonggaoI am not sure the DP-777's output impedance (at more than 100 Ohm) and the FL-100's input impedance (57k Ohm) is a match made in heaven.Yingtonggao
100ohms into 57kohms
This is a great/perfect match end of story, especially that you have more than enough gain. And if you look at internals the DP-777 the volume control is not a tacked on potentiometer on the output rca's, it is a analog domain volume control that is after the dac yet before the tube output buffers. This will be the most transparent/perfect way you can get the signal from your dac to the FL100 amp. If then you don't like this, by all means colour it to your liking with a active preamp of your choice, this is why ALL active preamps sound different as they are not a strait wire with gain, as Nelson Pass alludes to in his statement. And if other can't see this they cannot see the forest through the trees and believe in voodoo.
Cheers George |
Yingtonggao, just set the input impedance of your FL100 to the max, which is 57kohm and feed your AMR DP-777 straight in and use it's volume control, which quote is a "Direct-Coupled Analogue Volume Control." No extra caps in the signal path.
This will be the most transparent/dynamic sound you will get PERIOD! As it is basiclly then a straight wire from the 777 to the fl100 then (no impedance mismatches). And you will have bags of gain left over still on the AMR's volume control.
If after that you still prefer an active preamp, then it's the colouration/distortion of it you like, which is a bandaid fix for something else that's wrong. Remember it is impossible for an active preamp to extract any more music than what is on the disc and being presented by your DP777, it can just add artificial things, as it does not make music itself.
Cheers George
Just got an email from the maker of the FL100 and your amp is also dc coupled. No caps in the signal path from your DP777 volume control all the way to the speakers, that is a big plus always. |
What's wrong with just using the AMR DP-777 with it's volume control or just use a passive preamp like Lightspeed Attenuator or similar with just a pot in a box, no noise with passive pre's. And as you have such high sensitive speakers you are throwing money away using an active preamp, unless you like the colouration they can give.
Cheers George |
Not apologizing to you at all, just correcting your misinterpritation of Nelson Pass's statement, as you also did with my post.
Cheers George |
