George's Lightspeed is IMO one of the best PVCs made, but- 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. this quote is rendered entirely fictitious by the last sentence. IME PVCs usually have more coloration, not less, than a competent line section (although as I have pointed out in the past it is because the math of the situation goes against you when trying to use an outboard PVC, Nelson Pass or no; I am sure if he ran the math he would come to a similar conclusion). Try running 30 feet of cable between the PVC and the amps and you will see what I mean. I find that the better a line stage is, the more they sound like real music. Now if you really want to make a PVC work, the thing to do is install it in the amplifier so you don't have the math issues associated with the cable. Don_s, you were correct- I meant 'without'. |
An isolation transformer can indeed fix or sort out the noise issue mentioned by the poster. I have used them with good results.
Yes, the LS passive attenuator is easily one of the best buys in audio history. It does sound very nice and if I had a very low budget it would be high on my list. Both Charles and I are talking about best in class active tube preamps that cost many times more.
I, like Charles, simply wish George would stop saying we like Voodoo etc..That simple.
I also thank George for his unselfish DIY giving. I am a very active DIY guy and kind folks like George make it possible for me to play. |
The OP is going to have a hard time sorting out the noise issue with 104 dB speakers. I do not think line conditioners or isolation transformers are going to solve the issue. He has already said going direct with his CD player has worked. Maybe this is the solution. Based on this if he feels he needs to insert something in between I would have to recommend something that will not add gain. I would recommend either the LSA or a very good TVC (Bent Audio and Music First come to mind), and if there is a need to increase flexibility to have longer cables or to have peace of mind regarding impedance matching then something like the Pass B1 or Burson Audio buffer could work. An MP-3 set up as a tube buffer could work as well. |
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 |
George, no need to be shattered. The source you use or anyone uses is not perfect so fidelity to the source is not the goal. The end result of the music out of the speaker is.
An isolation transformer can and has in my experience removed ground related noise that no other method would. Sometimes this happens with certain gear - that is this unwanted noise. I had a noise issue that I could not get rid of until I used an isolation transformer. |
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
|
An isolation transformer from Jensen it different from what he has tried. |
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 |
I agree. He should have to use it. I liked the sound of a past system and the
only way I could keep,same components was to use a Jensen ISO tranny.
It rid the system of a buzz I could not tame in any other manner. Not ideal
as you say, but it worked and did not change my sound. In my case the
issue was between the amp and preamp. It was a buzz.
Just an idea.
The OP can call Jensen as they are very helpful and they can help
determine if this would be a strong potential fix. I bet they would be open to
letting him try and return it if it does not,cure the problem.
Almag here is the one who turned me onto the idea as well as another
Agoner who had the same issue and the Jensen worked wonderfully.
I assume here a nice tube preamp would deliver better sounding music and
this step is thus worth it. |
Charles1dad said: My point is don`t be condescending and dismissive to those listeners who chose an active component rather than his. I agree completely. I think that you have to look at the LSA in terms of value. It's an outstanding value and a very good pre-amp. George, I second Grannyring's accolades for your DIY support (this from someone whose DIY skills pretty much end at crimping spades and rolling tubes ;-) |
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 |
... 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... George, note that he is talking about a line level signal from a DAC, not a phono level signal. I am not aware of any preamp that comes remotely close to providing 40 db of gain from its line level inputs, even with the volume control at max. Typical numbers these days are in the teens, or even less. And with a DAC or other digital source, commonly the volume control of an active preamp will be set such that its gain, from input to output, is less than zero in terms of db. Bill (Grannyring), thanks for the acknowledgement. Glad I was helpful with that issue. Regards, -- Al |
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 |
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. You won't get any argument out of me on this! I am of the opinion though that passives *loose* detail, not that actives *add* it... I also agree that if you can get by will less gain, so much the better. So we do offer or preamps with no gain in the line stage, just our direct coupled tube output, which has no gain driven by the volume control. However: We have had pretty good luck with getting low noise without removing the gain stage in the preamp, even on speakers of that efficiency (we have customers using speakers that are 107db), which is why it is obvious that preamp gain is *not* the problem! **If it were, hiss would be the complaint, not buzz!** I feel like I did not put enough emphasis on that last sentence but I don't want to yell :) |
Atmasphere wrote,"I am of the opinion though that passives loose detail and not that actives add it".Right! I`ve believe this for a long time. That`s why the common complaint concerning passive/direct connection is less,tonal body,weight,timbre and dynamic presence-drive.These are real musical attributes not colorations. |
Well, guys, this thread just gained another dimension.
I am a firm believer of well-designed active preamps after trying a few passive ones. I do not exclude the possibility of passives work better in other systems, and in return I hope the supporters of passives don't decribe all active preamps as "colored".
The noise I suffered may be related to too much gain, but I've heard systems with more active gain and with the volume pot(s) at maximum, when there's no music playing, the system is totally silent. Modern components easily achieve 100+ dB S/N ratio, two or three of them hooked up in serial should not generate such an audible noise.
Anyway, you guys reply faster than I could try different options. But this thread is very insightful. |
Yingtonggao, what you report is a buzz. But you did not report hiss, which says to me that the gain is not the culprit. There is some hookup (like a ground loop of a poorly shielded cable) which is allowing the buzz to manifest. |
Atmasphere, you are right, I'd call it a buzz, not hiss. |
Yingtonggao, what this suggests to me is what I mentioned in my first post on this thread. It may be that the preamps you have tried so far have troubles with ground loops, but it could also be a problem in the amplifiers. Have you tried any of the suggestions I offered? |
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 |
Actually if a ground loop is present it will more likely manifest as a buzz. It is rare to see a ground loop only produce 60Hz! |
After almost a month the buzz remains with any preamp, and luckily I can still enjoy music running source-direct. The buzz is audible both above and below 140 Hz, I know this because my Avantgarde Duo Classic speakers have active sub crossed over around 140 Hz, and I hear the buzz from both midrange horns AND the sub. I may be able to hear a little hizz close up to the tweeter horn, but it's much less intrusive, and "normal" for almost any speakers. The buzz is independent of the volume setting on the preamp, so it's not source-related. Tuning preamp volume all the way down doesn't diminish the buzz, turning preamp volume all the way up does add a little more noise, but when I listen I rarely go beyond 10 O'clock. I should mention that I did take some wires to connect the chasis of the pre and power amp (common grounding), nothing improves. I did not buy a Ground Zero. |
Yingtonggao, did you try using a ground cheater on the power cord of the preamp? If it works it is not a solution, but an indicator. |
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 |
Finally got a noise-free pre/pwr combo! Audio Mirror T-61 preamp + Cary 300SE monoblocks. I don't know why but this combo is free of noise/buzz/hiss. Sounds wonderful too! The best I've heard with Avantgarde Duo.
Substituting either pre or pwr with another brand and the noise comes back.
Unfortunately Cary discontinued the 300SE. Does anybody know the sonic difference between 300SE and 300SEI? |
Active tube pre with 300b SET, you`re good to go. Congratulations with solving the problem.Now just enjoy your music. |
There may not be much difference in the circuitry between the SE and SEI but with the SE being mono blocs and the SEI being an integrated, my guess would be the SE monos would sound better as they don't share a power supply or chassis. The other advantage (if you want to call it that) is that you can choose your own preamp when working with power amplifiers vs integrated amps. |
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 just said his sound is the best he`s had so far with the current Avantgarde speaker set up. Leave well enough alone and appreciate the new found sonic joy. |
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 |
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. This is only true in certain situations can cannot be regarded as universal. In this case we are seeing testimony that the active unit is sounding better than direct. |
He hasn't said he's tried this new amp (Cary) direct yet.
Cheers George |
Yes, I did try preamp-less and preamped options between the DP-777 and Cary 300SE. I prefer the preamped sound, being more ripe, full-bodied, and solid. In comparison the preamp-less sounds a little cardboardy and less 3D, the difference is not as prominent as in some system though, but I consistantly find a good active preamp helpful in various systems (I've bought and sold hundreds on audiogon). Last night I invited a cellist friend to my home and we listened to various cello/string pieces, he confirmed that the preamped sound is closer to a real cello.
George, you are right the Cary is a low-gain amp and it certainly helps to reduce system noise in this case! But a good active preamp is the soul of a system and many people can't live without it. Nelson Pass has a point, but other designers at Conrad Johnson, Audio Research, Supratek, etc are not dumb either.
I should mention that Audio Mirror's T-61 tube preamp is a tiny little wonder for ~$1K. It replaced a trusty CJ Premier 14 tube preamp as well as an Audia Flight Pre SS preamp in my system. It's innovative in using LED (instead of a resistor) to ground the tube circuitry. |
The findings of your musician friend comes as no surprise to me or others. When the full body, tone, color saturation and dynamics are preserved the sound is more realistic and live like. This is confirmed repeatedly when listening to live music. Components that are incapable of delivering this vital (and obvious) musical information are deficient. The complaint that passive or direct can sound lean, thinner and less dynamic is subtraction of information from the audio signal it would seem. If a good active preamp avoids this flaw that would be desirable.
Charles, |
"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 |
|
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. Another thread, still missing the point. People don't just listen to a DAC but a system of components. Every component is colored and has a sonic signature. They mix and match to get proper synergy. It's possible they don't like sound of DAC with just straight wire/gain but only in a system because of synergy. I'm sure you can build a very nice system with a passive pre. There's more than one way to skin a cat. With all the hype, I bought a Lightspeed Attenuator. It's good but NO comparison to my active pre. The active has superior imaging with well defined edges, 3D, dynamics, vivid, color ... My active pre is relatively expensive, it's GREAT value with the quality of sound it produces. Same with my speakers, relatively expensive but I prefer over speakers costing 2X+ ... Components don't have to be low price to be good value IMO. |
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 Pretty much any component in one's rig has a sound of its own, i.e. is "colored". This includes also the cables, which you keep on bring up as your reference. Can you be more specific and tell us which brand of wires are you talking about? |
To his credit although Atmasphere (Ralph) is a manufacturer, with a vested interest in his own gear, I find his responses to be intelligent and open-minded.
George is basically insisting that his way is the only way- and that is just wrong.
FWIW, I experimented with bypassing the line stage and running directly from a phono pre into the amps (It was a Steelhead, which has more circuitry than a stand-alone passive pre, but the overall concept is similar and I've since replaced it with something a little more antiquarian, using LCR and transformers, along with old telephony tubes, which to my ear sounds better). Although the bandwidth was great, bass to die for, the presentation sounded threadbare and very 'hi-fi.' Introducing a good line stage into the mix added a level of heft and palpability that I associate with real instruments. Changing line stages last year upped the ante even more -going from the Lamm L2 to the Veloce (Lithio or version 2). Piano is a hard instrument to reproduce. For years, we had a big Bosendorfer downstairs. I know what a real piano sounds like. It's a beoytch to reproduce, and beyond the gear is the quality of the recording, how the instrument is miked, how the record is mastered, etc.
So much is source and system dependent, and so many other variables make up a system, I just can't buy into 'my way or the highway' approach to hi-fi.
Sorry George, you've lost me on this thread. |
Knghifi and Whart,
This improved weight,heft,palpability,3D,dynamics,vividness you hear, well you guys just like pleasant colorations.Never mind that it sounds closer to live instruments,doesn`t matter. If you don`t hear it as george does,you`re wrong. Why is that so hard for you guys to understand.Grannyring and Knghifi(and others) purchased his passive and preferred their active preamp,wrong choice guys.Why be silly and choose the component that sounds more realistic,who wants that anyway? |
Charles- I'm open to learning, considering other approaches and contributing where I can. I can also enjoy a good debate, but after too many years on the intraweb, don't have any interest in sniping, at George or anybody else. I enjoy (and enjoy sharing) the excitement of discovery, the fundamentals of 'best practices' in set-up, the detective work of trouble shooting (not easy in void of hyperspace) and fiddling with tweaks that don't cost a fortune. I also enjoy hearing from others who consider this an adventure. There are many here that seem to approach things the same way- they don't discount novel or antiquarian approaches ( although there may be some legitimate skepticism); but, at bottom, folks here are often willing to jump in and spend real time, thought and energy to help somebody troubleshoot a problem or answer a question. (I've certainly benefitted from that over the years here).
As somebody put it in relation to a discussion about the sonic differences among various pressings of the same record, it is still more art than science in a lot of ways, even though sound engineering principles should underlie what we do.
I'm not dumping on George, but find the endless drum beat to be monotonous, and ultimately, counterproductive, at least for me. |
Wow, so much fight after just one day! George and Charles, we've already known you are big fans of passive pre or source-direct, but at the end of the day, some of us will turn on an active preamp and some will go preamp-less. Who gets more fun out of music/audio is impossible to determine.
I recently found my iFi iUSB Power supply a great tool to charge my cell phone --- faster than my Samsung Note II's own wall-wart power supply. Yes it cost $199 plus shipping thus qualifies the most expensive cell phone charger I ever use. But I had more fun using it to charge my cell phone than to power my USB DAC ---- I was smiling ear to ear watching this little audio gem charging a cell phone (silly, I know). Anything wrong with that? Can you guys find me a passive cell phone charger that works better? |
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
|
Whart,
I understand where you`re coming from and agree.What`s annoying to me is the condescending 'know it all' attitude toward those who`ve reach a different conclusion from what he believes. Well I `ll leave it alone now,enough has been said.
Charles, |
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 |
This thread has been quiet for some time but has yielded some well sorted out theories.
I stumbled on it with hopes of finding a solution to a hum problem that seems to center around a phono preamp and like others on here, brought to light by some high efficiency speakers.
I've tried a star grounding system, moving power/ICs, etc.
Have dedicated lines and sub panel, a Balanced Power Technologies 3.5 Sig Plus. After I installed the BPT, the edge I was hearing in the presentation took a step back, and yes, the presentation became more natural.
Along with it came the hum, which was previously more subdued.
I will spend some time this weekend chasing down possible sources, not looking forward to this.
Question is: could the Power conditioner's large transformer be reaching 3 feet or so to the phono pre? |
Hum is 60 or 120 Hz noise from the power, and there are two way to pick it up, either conducted or radiated.
Radiated powerline noise is when you have a high current device and it throws out a magnetic field. Any high impedance conductors (your line levels and phono lines) in the field will have an induced 60 or 120 Hz voltage picked up on their wires. You test for this by moving the high impedance wires around. If that causes any change, you have a radiated energy pickup problem. Knowing that, then you can do things like try to improve wire separation (the energy falls off as the inverse of the square of the distance, i.e. it falls off rapidly), or use shorter wires (less pickup area), or re-orient the wires to make them perpendicular to the radiating source (max pickup is when they are parallel to the radiating field).
This radiating magnetic field normally comes from the powerlines or from the power transformer in the high current devices like the final amp power supply.
Trying to shield lines from the 60 or 120 Hz magnetic fields is useless, because at that low frequency the magnetic field cuts through shielding materials very easily. Shielding only works to guard against high frequency pickup. Distance, wire length, and orientation are your best friends.
The other way to pick up hum is by a conducted path. The 60 or 120 Hz noise is traveling through the conductors and getting back onto the input source. If the test above for radiated pickup doesn't work, then you should try electrical isolation methods such as messing with power routing (star or independent outlets) or putting a noise suppressor/filter on the phono power.
Divide and conquer... find out which of the two problems you have first, so you narrow down the type of action you need to take.
|
Hello Dentdog,
I hope you soon find an answer to your system hum issue. I use the same BPT unit and it's terrific! I have no hum problems with its use un my system. |
Hi Charles1,
As with most things audio the devil is in the details. The BPT certainly does a lot of things favorably, a sense of ease permeates the music now and is very pleasing. Will have to don my Sherlock hat although Inspector Gadget is a more appropriate. I'll get it, and along with the solution a bit of education. |
Dentdog,
You were certainly given very solid feedback from Tom32. I believe you'll get this problem solved. |
