Posted by Rich Brkich (D) on May 18, 2006 at 17:04:52

In Reply to: Joule Electra tube noise w/ Merlins (long question) posted by rottenclam on May 18, 2006 at 16:43:01:

Are you VZN-100s MKIV or MKV... just want to be sure what you have. If you have one of the newer version of the 100's they should have a mute switch on the input. Does the noise occur when the input of each amp is muted? Is the noise level the same in each channel?

Are you using any special power conditioning or power cords on the amps?
Happy Listening,
Rich Brkich
Retailer & Audio Asylum Industry Liaison

• Re: OK... lets see... - rottenclam 19:00:07 05/18/06 (2)
  In Reply to: OK... lets see... posted by Rich Brkich on May 18, 2006 at 17:04:52:

  Rich, thank you for your attention.

  My power cords have remained stock (the standard Chinese "Well Shin" cords that Joule provides), and I have experimented with a few different configurations of giving them power. For a while I was using a Shunyata Hydra, but later sent that piece packing. Currently I have the system on a Cablepro bar (the latest one endorsed by Naim) which is made by Wavelength (the company out of Texas, not to be mistaken with Gordon Rankin's company). This Cablepro bar goes directly into the wall. For a while, in another room (with another system), I did have the Joule/Merlin system plugged into the Hydra, and later the Cablepro, which then fed into a PS Audio wall outlet.

  With the exception of power cords, which as I said before, remain stock, all cabling is Audience AU24. My Joules are the latest editions, having been delivered in October of 2005, and I have experimented with the mute switch both on and off. The noise remains. Both channels have it, although the right channel maybe has it a hair worse. Sorry, I dont have an SPL meter in order to confirm how much of a differance the sound is between channels, but from my ears, I can tell you it is very very slight.

  The power conditioning seemed to have little to no effect, but as I said, the only "conditioner" I've used was a Shunyata Hydra 4. I am open to any suggestions, but in your experience, is there just some noise with the Merlin/Joule combo that comes with the territory, or are they supposed to be very quiet?

  -Jake
  
  

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  • Re: OK... lets see... - Rich Brkich 13:44:32 05/19/06 (1)
    In Reply to: Re: OK... lets see... posted by rottenclam on May 18, 2006 at 19:00:07:

    ... thanks for the addtional info, it helpts allot. With the amps muted and nothing connected to thier inputs, that pretty much tells me the noise you are getting is from the amps..

    I am not familiar with the cable pro, but I don't think it is helping or hurting the issue here as I am reasonably sure the issue you are dealing with is not power line related as it sounds like you are syaing that indpendant of whatver power cord or power line conditioning you have used, that the noise is still there in the same manner.

    Lets move onto your amps... The MKVs are the quietest OTL Joule has made. Having said that, that does not mean these amps are dead quiet. Thier design (floating power supplies and the circletron design topology) mean that if things are not perfectly in balance, some noise is going to be generated and this is uusally the case. Also there can also be some variability between pairs... some being a little more quieter or noiser than others. I have knwon Jud to do some tweaking (probably fiddiling with grounds inside the amps) to some pairs of OTL to get them a quieter. I have heard a few pairs of MKV version Joule VZN-100 OTLs on VSMs and the noise level is pretty low on these amps... requiring you to be standing next to the speaker to be able to hear the noise - these amps though are never dead quiet though (no amp is actually and the all have varying amounts and types of noise) and the more effiecient the speaker, the greater the problem. Having said that, you may be able to get things a little more quieter by getting the balance between the two halfs of each amp better matched. I would like you to check the DC offset - that extra button near ther bias buttons (no music , inputs muted) of each amp and let me know what each amp is reading. Depending on what you are reading there I amy have you tweak bias settings to get things dialied in a little better which may help reduce the noise a bit.

    I can imagine in a setting where the noise floor in the listening room is low enough, that even a fairly quiet pair of VZN-100s when hooked up to a efficent speaker like the VSMs will have a noise level that is audible from several feet away. What hurts here is that the noise tends to be buzzy in nature which is more apparent to the ear in nature than a hum.

    Now, there are seom possible issues we have not considered here....

    1) RFI.. probabaly not a issue here..
    2) Power line issues (which convential power filter type products you have used cannot possibly correct).
    3) There is something amiss with the common variac power supply unit that is causing both amps to be more noiser than they should be... never seen this before and I doubt this is the case.
    
    Happy Listening,
    Rich Brkich
    Retailer & Audio Asylum Industry Liaison
    
    

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    • Re: OK... lets see... - rottenclam 22:37:33 05/19/06 (0)
      In Reply to: Re: OK... lets see... posted by Rich Brkich on May 19, 2006 at 13:44:32:

      Rich,

      Thank you for such a thorough and thoughtful response. As you said, my expectation should be tempered in accordance with the nature of tube amps, which tend to be more noisy than solid-state. And yes, I know that some tube amps are more noisy than others, my curiosity is just whether the reputable Joule/Merlin combo is as noisy as my setup has turned out to be.

      Last night while listening to Stevie Ray Vaughn, Sigor Ros, and Miles Davis; I was again struck by how deeply I can hear into the recording, but it was only during the very delicate parts of the "Round About Midnight" Miles SACD that the hum bothered me. Unfortunately this is heard quite predominantly during classical music, of which there are so many delicate and quite parts, so that is a bummer.

      My DC Offset seems to be reading normal. I usually check it every couple of days just to make sure that it is not at 0 or 1 (it seems to be anywhere from 5 to 40) and I wait until the amps have been on for at least an hour, before checking. I have experimented with the feedback controls, the variac settings, and the bias, all in order to fit my room and my musical tastes. I keep the amps between 64 and 65, the output tubes around 27, and the input/driver stages close to 120. My feedback is set to around 7 or 8 o'clock, depending on whether I am in a more musical or analytical mood.

      I have been in contact with another Joule customer, with a similar system, who is experiencing the same thing, so I will update you with our collective findings. He took delivery of his Joules in December (mine came in October), so maybe it is a current tweak from Jud that is not working out as planned.....or not.

      Updates to follow. Thanks again Rich.

      -Jake
      
      

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