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Dave Slagle Monoblock Transformer Volume Control Build

Discussion in 'DIY' started by SET12, Feb 7, 2016.

  1. mkane

    mkane AK Subscriber Subscriber

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    Not sure myself but it get's better each listening session. Myself, don't have a problem with attenuation but it's set up is strictly analogue.
     

     

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  2. rogerfederer

    rogerfederer AK Subscriber Subscriber

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    i switched amps. took out the tpa 3116, which is about 20wpc. put in darling clementine flea watt tube amp, which is 0.75 wpc. still more volume than i want. plus i put in 12 db harrison labs attenuators. this is with a tube tuner, not a digital source.
     
  3. SET12

    SET12 Super Member

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    It wouldn't surprise me that the TVC has the edge. You could always use two resistors/channel to attenuate the volume some.

    IMO one thing that the TVC does is enhance the sense of space. There is much more air between everything, depth, height and width is also enhanced as well as dynamic punch.

    I was doing some listening the other day to CD's and I heard some vocals in the background when the CD was stopped. It definitely was a ground loop from my wifes Marantz PM5005 amp. I then noticed that I had her separate Tuner on. Of course the Marantz's grounds are not switched with the hots, I'm glad I set up my TVC's selector switches to switch the grounds as well as the hots to eliminate ground loops.

    As to burn-in you could feed the tuner outputs to the TVC for a few weeks. I haven't done this yet but I'm going to.

    Nice looking!

    SET12
     
    Last edited: Apr 17, 2016
  4. mkane

    mkane AK Subscriber Subscriber

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    Was looking for something a bit different is all.
     
  5. SET12

    SET12 Super Member

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    Don't we all!
     
  6. Tillerman

    Tillerman Active Member

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    Did you say whether this happens with other sources (such as CD) or only with your tuner?
     

     

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  7. rogerfederer

    rogerfederer AK Subscriber Subscriber

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    tuner has the most output, but needed the 12 db attenuators to tame the DAC
     
  8. Tillerman

    Tillerman Active Member

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    Thanks. Do you know the DAC's rated output voltage?
     
  9. rogerfederer

    rogerfederer AK Subscriber Subscriber

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    Last edited: Apr 18, 2016
  10. Tillerman

    Tillerman Active Member

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    It seems like it is more than a DAC, i.e. a DAC plus a preamp. As I am sure you know, most DACs output around 2 to 4 volts. Where do you run the volume on the Emotiva?
     
  11. rogerfederer

    rogerfederer AK Subscriber Subscriber

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    i have it all the way up
     

     

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  12. SET12

    SET12 Super Member

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    I get the impression after looking at it a second time that it has a digital volume control feeding an internal line stage from what the manual says. So it looks as though there is no separation of the two sections. And no analog inputs. That's really unfortunate.

    I guess what I'd do is feed the DAC output with its volume turned down enough so that its at a reasonable level at the TVC's first step. And see how it sounds.

    In the end I don't think I'd like turning a digital volume down and using it like that. If it was a regular DAC the TVC could replace the line stage or at least the line stages conventional volume control whether a pot or resistor ladder which IMO is far superior.

    In the end I would be looking for a different DAC or just use the DAC by itself which case would require some kind of switching setup instead of cable swapping all the time. Especially listening to other analog sources.

    As far as a DAC volume I can why they did this but I can't see why they didn't include any analog inputs, but that would of made the DAC more complicated and more expensive because they would of had to do Analog to Digital conversion to make use of the Digital Volume Control of the DAC.

    I'm very sorry to hear of this trouble.

    SET12
     
  13. Tillerman

    Tillerman Active Member

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    Location:
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    As usual SET12, you beat me on a reply. I had found the following advice from you in post #13 in the other thread (Klipsch R28F):

    So addressing some of your concerns. I think you were concern about having 3 inputs and whether it was OK to put a TVC after your line stage.

    Putting a TVC after a line stage is not really a good idea as the gain would likely produce many volts across the TVC causing it to be saturated. One could turn down the volume of their preamp but that would defeat some of the benefits of the TVC like lack of compression. So really after a source is really the best bet.
     
  14. SET12

    SET12 Super Member

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    Thanks Tillerman, In theory a digital volume control would be superior to a conventional control such as a pot and resistor ladder. But in practice there are many poorly implemented designs that truncate resolution say from 16 bit down to 12 bit. I have heard some pretty bad controls myself. But it is likely with a digital volume control not to experience compression the worry for me is the truncated information which BTW as I recall on the worst digital volume control that I recall it sounded pretty dark. So some are quite good and some not so good.

    Wiring switches for 3 inputs is a bit more of a chore than doing it for 2 especially if like me you want the grounds switched as well. When I heard the tuner cross-talk on my wife's Marantz (due to lack of switched grounds) I just smiled knowing that it wasn't going to happen with my TVC's switched inputs. With the Marantz I just switched the tuner completely off and that took care of it. Another benefit of switched grounds is that it prevents chassis flux of source components from sending currents down IC's which can affect the sound quality as well.

    SET12
     
  15. rogerfederer

    rogerfederer AK Subscriber Subscriber

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    Well, with the 12db attenuators in the chain I can keep the tuner volume from being too high. At the same time I can turn up the TVC knobs to get enough volume with the DAC.

    I get impressive detail using the TVC so it is a keeper at this point. However, I am disappointed it can't attenuate more effectively.
     
  16. mkane

    mkane AK Subscriber Subscriber

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    Could you double up on the attenuators?
     

     

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  17. rogerfederer

    rogerfederer AK Subscriber Subscriber

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    there are output pots on the tuner, it is a restored fisher fm 100b. i'd prefer not to use them (unless really necessary) as the whole point of going to the TVC is to stop using conventional pots wherever possible.

    the lack of full attenuation (not a problem with the LDR, btw) is a disadvantage of the design. not a fatal flaw, by any means.
     
    Last edited: Apr 23, 2016
  18. Tillerman

    Tillerman Active Member

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    SET12 - Since you mentioned digital volume controls, one of my preamps (Audio Alchemy DLC) uses a Cirrus CS3310 for digital attenuation. It is my only preamp with remote functionality.
    IMG_6193.JPG
     

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  19. SET12

    SET12 Super Member

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    Your DLC has some nice reviews from what I found on it. I think it would be pretty interesting to see what you notice between the two comparing the digital volume to the TVC and especially a comparison of lower volume levels between the two.

    I certainly would put the TVC between the source and the DLC and based on what I read you can bypass the DLC's gain if you choose.

    I think it would be interesting to compare the two with and without gain at both higher and lower volume settings.

    SET12
     
  20. Tillerman

    Tillerman Active Member

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    261
    Location:
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    SET12,
    The DLC is an interesting preamp, that sounds quite good. I found an article from Rowland about their use of the CS3310 - interesting read.

    At some point, I will likely build a Slagle TVC, probably following your model of 2 inputs w/grounds switched to use with my DAC du jour (I have 3 to play with) and one of my FM tuners going into either a tape loop or aux input on my Yamaha C-2a. I like the idea of using the preamp's features and sound characteristics while taking the preamp's pot essentially out of the equation by having it maxed out or nearly so.

    If this happens, I will compare the DLC against the Slagle TVC - should be interesting.
     

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