Dartzeel Preamp Hiss

howiebrou

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I just got a Dartzeel Preamp tp demo at home with a pair of Analog Magic Apollo monoblocks. I swapped out another demo preamp from Synastec (which was silent) and the Dartzeel is a HUGE improvement.

However, there is a loud audible hiss from the speakers, a little like tape hiss of old. It is so loud that i can hear it over quiet passages. This preamp sounds fantastic so i want o get rid of the hiss and give it a fair demo. I was told to move the power supply for the Dartzeel further away from the preamp which i did but it didn't help. In fact when i moved it away i swapped the Kondo PC for a Crystal Ultra PC (which was longer). The hiss turned into a buzz! I'm not quite sure why the buzz occurred considering both PC are plugged into the same Furutech power distributor.

Should I try connecting the preamp to the wall? Also plugged into the Furutech is my CH Precision C1, AR Ref 2 phono and Avid Acutus power supply. The hiss remains whether it is my C1 dac playing or vinyl.

I understand the Dartzeel power supply needs careful positioning but have no idea where to put it or where to plug it in.

Thanks

Howie
 

Elliot G.

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Hiss and buzz are two separate issues. Buzz is a grounding issue and just because those power cords like alike doesn't mean they are the same internally. It sounds like one of those power cords has a floated ground and that is why one hums and one doesn't.
The Hiss is another kettle of fish and very well could be a a miss match between the components.
 
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howiebrou

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Hiss and buzz are two separate issues. Buzz is a grounding issue and just because those power cords like alike doesn't mean they are the same internally. It sounds like one of those power cords has a floated ground and that is why one hums and one doesn't.
The Hiss is another kettle of fish and very well could be a a miss match between the components.

Thanks for the comments. As far as I know both power cables are grounded. The crystal one definitely is so I wonder why it buzzes. The Furutech distributor is definitely grounded too. Neither have caused such an issue in the decade or more that I have used

I did think about whether the match of Dartzeel and Analog Domain was causing it. I have no specs to suggest why this would be the case though.
 

howiebrou

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Just for info, the output impedance of the Dartzeel is 600ohms, the input impedance of the Analog Domain is 10,000Ohms giving a ratio of 16.7 which i think is within the accepted range of 10-20.
 

Sencha

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hi Howie,

Just to say my Dart pre is dead quiet and have no audible hiss or buzz, this is something not associated with the pre amp in general. When I first got it I did have a bit of hiss which was diagnosed by Herve Delétraz as me having the power amp too close to the pre amp when I was playing LP’s. Once I moved the amps further apart all inputs were quiet. I cannot comment on the power cords but if the batteries are charged you should be able to remove the power cord and still use the pre amp, that should rule that in or out. I would get back in touch with your dealer or Dartzeel themselves who hopefully can diagnose the issue. I would hope either will sort this out for you and yes, it is a great pre amp!!
 
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howiebrou

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hi Howie,

Just to say my Dart pre is dead quiet and have no audible hiss or buzz, this is something not associated with the pre amp in general. When I first got it I did have a bit of hiss which was diagnosed by Herve Delétraz as me having the power amp too close to the pre amp when I was playing LP’s. Once I moved the amps further apart all inputs were quiet. I cannot comment on the power cords but if the batteries are charged you should be able to remove the power cord and still use the pre amp, that should rule that in or out. I would get back in touch with your dealer or Dartzeel themselves who hopefully can diagnose the issue. I would hope either will sort this out for you and yes, it is a great pre amp!!

Thanks. The Dart is about 12 feet from the amps so that shouldn't be an issue. The amp has a low gain setting so I will see if that helps and will try to disconnect the power umbilical too. Thanks.
 

microstrip

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Are you using your amplifier at maximum gain (35d) ? If so you can try switching it to 26 dB. The older NH18NS preamplfier was just adequately silent and paired with a high gain and high efficiency chain could have noise problems.
As far as I know the more recent units have better signal-to-noise ratios.
 
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XV-1

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Are you using your amplifier at maximum gain (35d) ? If so you can try switching it to 26 dB. The older NH18NS preamplfier was just adequately silent and paired with a high gain and high efficiency chain could have noise problems.
As far as I know the more recent units have better signal-to-noise ratios.

That Is what I was thinking. The analog domain amp has 26db gain and stupidly high 41db gain.
Definitely needs to be used at 26db gain with the Dart.
 
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Folsom

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Well it's a battery preamp, have you tried unplugging the power supply and running strictly battery to see what happens?
 
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howiebrou

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Thanks to all. I spoke to Angel Despatov and he also suggested lowering the gain. Job done and all Is quiet! I am chuffed to bits!
 
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Sencha

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Hi Howie, am glad you got to the bottom of the problem, would very much like to hear how you get on with it after you have enjoyed it in your system for a bit. Just wondered if you have tried the 108 as well?
 

spiritofmusic

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Well done Howie. I have more than one source of noise in my system. One easily solved ie getting balanced transformer and air arm pump out of my room. One that should have a solution soon ie sorting Zus subs hum. One a bit more tricky ie tubes noise from my Nats triodes into my high eff Zus.

So, I can feel yr relief in sorting yr issue. WBF can come good despite occasionally being a shouting match LOL.
 

howiebrou

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Well done Howie. I have more than one source of noise in my system. One easily solved ie getting balanced transformer and air arm pump out of my room. One that should have a solution soon ie sorting Zus subs hum. One a bit more tricky ie tubes noise from my Nats triodes into my high eff Zus.

So, I can feel yr relief in sorting yr issue. WBF can come good despite occasionally being a shouting match LOL.

No you guys came real good this time. I am very relieved. I sat there thinking, this is exactly the sound i like but that bloody hiss would drive me around the bend. Now the hiss is only when i put my ear up to the drivers which is better than my valve amps were.
 
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howiebrou

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Hi Howie, am glad you got to the bottom of the problem, would very much like to hear how you get on with it after you have enjoyed it in your system for a bit. Just wondered if you have tried the 108 as well?

Thank you. It's not a bad combo at all. I haven't had the chance to try the Dartzeel 468 yet though...
 

spiritofmusic

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Howie, my Nats 211s tube hiss is audible up to 12" from drivers, and perceivable, "just", on v delicate music from the listening seat. However despite this, I think I would truly struggle to go SS.

Just like the temptation to ditch "noisy" vinyl for streaming. Many reasons in favour, none compelling enough.
 

howiebrou

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Howie, my Nats 211s tube hiss is audible up to 12" from drivers, and perceivable, "just", on v delicate music from the listening seat. However despite this, I think I would truly struggle to go SS.

Just like the temptation to ditch "noisy" vinyl for streaming. Many reasons in favour, none compelling enough.

The dart hiss was audible across the room before i lowered the gain. I don't mind valve buzz or hiss if it doesn't affect the listening experience. 12 inches seems perfectly acceptable. Streaming is fine for general listening and very convenient for trying new music but i still prefer vinyl for critical listening.
 

Elliot G.

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The dart hiss was audible across the room before i lowered the gain. I don't mind valve buzz or hiss if it doesn't affect the listening experience. 12 inches seems perfectly acceptable. Streaming is fine for general listening and very convenient for trying new music but i still prefer vinyl for critical listening.
if its making noise it is always making noise. Therefore your system is playing and amplifying that noise. You may not hear it or want to hear it but it is still there in some capacity and it does effect the total resolving power of your system. Sometimes you don't know whats messed up until its gone. I think this is very similar to grounding in its effect not its cause or sound. You are not aware of the differences until it is done.
I said yesterday that there was some mismatch in your system and if it is doing it still then there is. My opinion that this is not ideal Howie.
 

Folsom

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if its making noise it is always making noise. Therefore your system is playing and amplifying that noise. You may not hear it or want to hear it but it is still there in some capacity and it does effect the total resolving power of your system. Sometimes you don't know whats messed up until its gone. I think this is very similar to grounding in its effect not its cause or sound. You are not aware of the differences until it is done.
I said yesterday that there was some mismatch in your system and if it is doing it still then there is. My opinion that this is not ideal Howie.

Audible noise means it isn't modulating the original signal, so I disagree that it's always inherently bad. Some beloved amplifiers are simply "noisy", and they are revered anyways. If you have modulating noise and audible noise, that matters. In general I'd say if you can't hear it anywhere near the listening position it isn't an issue so long as it isn't a hum.

Hum does mean a loop typically, so I agree there, that is usually affecting the signal. Once again, I say, try disconnecting the PSU and listen (the battery will be charged and last for a long time, then just plug it in between listens).
 

Empirical Audio

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Hiss can be from the design itself, or from a ground-loop picking up RF.

Try disconnecting the preamp cables at the amp and if it still hisses, then it's the amp itself. Best to short the inputs as well if you can.

If the hiss goes away with no preamp connected, then it's a ground-loop. This can be fixed with isolation or lifting grounds, which I don't recommend. A good transformer isolator is a Final Drive which can do balanced or SE or combinations.

Is the connection between the pre and the amp balanced or Single-ended?

Steve N.
 

howiebrou

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if its making noise it is always making noise. Therefore your system is playing and amplifying that noise. You may not hear it or want to hear it but it is still there in some capacity and it does effect the total resolving power of your system. Sometimes you don't know whats messed up until its gone. I think this is very similar to grounding in its effect not its cause or sound. You are not aware of the differences until it is done.
I said yesterday that there was some mismatch in your system and if it is doing it still then there is. My opinion that this is not ideal Howie.
Thanks for your thoughts. Yes they might not be the perfect match but they do sound good! I guess the Dart 468 must be the best match which is why I tend to have matching amp and preamp. Unfortunately Analog Domain doesn't make a preamp.
 

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