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New Op Amps for a Music Hall DAC 25.3

Discussion in 'DACs' started by E-Stat, Mar 2, 2018.

  1. E-Stat

    E-Stat AK Subscriber Subscriber

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    While most of the time folks talk about the converter chip itself used in a DAC, I find that much of the sound quality you actually hear is due to the analog output stage. Which is just another line stage in the pipeline. Op amp chips are clearly very cost effective with even the most expensive ones running five bucks or so and most about fifty cents.

    I read about discrete JFET based modules that can replace a wide range of common op amps and decided to give them a whirl. Burson Audio located down under is one of several vendors who makes pin compatible designs using devices like I find in the Audio Research DAC8 used in the main system.

    Since the Music Hall folks use standard 8 pin dip sockets, replacement of the three dual op amps - two OPA2134s and one OPA2604 - (this is a balanced design) took only minutes. Not wanting to smoke the new units with incorrect orientation, I took the measure-twice, cut once approach. While earlier designs had much higher current requirements, the V5's pose no challenges to the 25.3.

    Results? Even with the modest garage system using a Raspberry Pi/DigiOne renderer, Hypex NC502mp amp and modified New Advents, they definitely elevate the performance in many subtle ways. You hear more inner detail without any false brightness. There's better focus with voice and instruments. You're better able to follow rhythms in the background. Closer to what I find in the main system. Highly recommended for a comparatively modest cost.

    burson1.jpg

    burson2.jpg
     
    Last edited: Mar 2, 2018
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  2. SWL3600

    SWL3600 Super Member

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    I went this route as well using the Sparkos discrete opamps in a Maverick Audio Tubemagic D2. Totally worth it.
     
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  3. kray

    kray HE>i Subscriber

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    Have exact mod.

    I also modded an old Music Hall cd25.2 to OPA627's. Great upgrade.

    Op-amp upgrades are a nice easy way to change the sound/quality.
     
  4. soundmig

    soundmig AK Subscriber Subscriber

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    +1 for the Sparkos ... I replaced the op amps in my Forte pre-amp with Sparkos discrete op amps - major improvement!
     
  5. BigElCat

    BigElCat Mmm Hmm Subscriber

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    I have a Music Hall DAC 25.3 in my main system. The tube has been upgraded to a Mullard CV2493. The Mullard made a noticeable improvement in the sound quality; it was worth the $120 it cost. I have a Singxer F-1 (XMOS 208) in place of the USB input. The XMOS 208 is also a nice step up.

    I'm seriously thinking about these Burson Audio JFET/discrete opamps.

    How long have you been listening to them ? Do you suppose they're still burning in ? And the stock power supply shows no strain ?

    What did you order exactly, the two dual set (@$100), and one dual (@$60) ?
     
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  6. E-Stat

    E-Stat AK Subscriber Subscriber

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    I use the balanced outputs where the tube is bypassed.

    I installed them just over a week ago. I suspect they are still burning in a bit. Definitely no strain with the V5s - note that others have used the older version with nearly triple the current requirement.

    Exactly. Three V5Ds.
     

     

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  7. BigElCat

    BigElCat Mmm Hmm Subscriber

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  8. Gibsonian

    Gibsonian Super Member

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    Am using V4's in my electronic crossover with good success. The V5's were tried first but failed after a bit due to voltage swing limitations.
     
  9. E-Stat

    E-Stat AK Subscriber Subscriber

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    If you don't mind sharing, what crossover is that and which op amps did it use originally?
     
  10. BigElCat

    BigElCat Mmm Hmm Subscriber

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    I'm curious, too. Wouldn't that be a problem the crossover power supply ?
     
  11. Gibsonian

    Gibsonian Super Member

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    It's an Ashly XR2001, which has been recapped where there are electrolytics. Have also eliminated unnecessary coupling caps. I don't remember the opamps for sure, thinking 5532's? If you've had an electronic crossover opened or viewed a schematic, you'll see several opamps in there unless discrete (Pass Labs, Pioneer D23) I will eventually replace all, but still have 4 more positions to go. The other positions I've replaced I installed LT1364's, which are quite good, and close in performance to the Burson's. The XR2001 is a really good sounding unit stock, and responds well to upgrades.

    Nope, not running out of juice yet. I do have oversized PS caps in place that likely help some. I'm thinking if I placed the V4's in all opamp positions, I could have an issue with sagging PS.
     

     

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  12. Gibsonian

    Gibsonian Super Member

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    Regarding Burson's, V4's swing +/-20V, the V5's are +/- 15V. Looks like the V5i and V6's are 16-16.5, so think they increased this for a reason. I did read that there were more than a few reported failures with the intro of the V5's back when I experienced failures with the V5's. Burson will stand behind their product though, that is for sure.
     
  13. E-Stat

    E-Stat AK Subscriber Subscriber

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    Not a challenge for my application. The OPA2134s have a max swing of 18V and I suspect most applications don't run at max.

    I note that the late 70s era 5532 design can go to 26V!
     
  14. Bill Ferris

    Bill Ferris Super Member

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    Very interesting to stumble across this post, E-Stat..

    Ref : the 5532`s, I started swapping out lessor chips(1458/4558) in the mid eighties with the 5532`s in all kinds of audio gear with the same pin outs and noticed a improvement in the SQ, in which I figured was due, amongst other things, was the speed
    improvement(rise time) of the later generation OP amps..
    Starting with upgrading my MXR 31 band EQ`s, before "testing" them out on my hapless customers gear !!


    Though, I started later to read about the esoteric OPA series HP becoming available later. I didn`t pursue the further upgrade, as all involved were impressed with the SQ of the 5532`s performance verses price point.

    Thanks for stirring my two remaining brain cells !!

    Kind regards, OKB
     
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  15. E-Stat

    E-Stat AK Subscriber Subscriber

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    The venerable 5532 is still widely used in McIntosh gear including the latest D-150 and earlier C47 line stages.

    The Burson discrete FET modules take the sonic refinement of that fifty cent op amp to a decidedly higher level.
     
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  16. Gibsonian

    Gibsonian Super Member

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    5532 is not bad but easily bested with later offerings. Am going to try OPA1612 next, have the adapter boards from SOIC8 to DIP8 headed my way. To date, OPA627 is the best sounding IC I've tried in DAC or anything else. Hard to find fault with it from top to bottom. Pricey but cheaper than the Burson.

    www.ti.com/lit/ds/symlink/opa1612-q1.pdf
     
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  17. Bill Ferris

    Bill Ferris Super Member

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    Yes, thank you, I`m aware..
     
  18. BigElCat

    BigElCat Mmm Hmm Subscriber

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    I ordered three of the Burson V6 Vivids.
     
  19. Guido57

    Guido57 New Member

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    Location:
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    May I ask what the modifications were to the New Advents? I'm curious because the cost for these op amps cost as much as I spent on buying and refurbishing (foam, metal foil capacitors and a BSC circuit) a pair of NLA's. Are such speakers worthy of these electronic upgrades? And I ask this as a fan of the Advents.
     
  20. E-Stat

    E-Stat AK Subscriber Subscriber

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    Certainly. Not many and they weren't terribly expensive. Others have gone further, but the speakers most definitely revealed the improved transparency and focus of the Burson chips.

    1. Replaced crossover capacitors. Factory used a 13 uF electrolytic. I use a 1 uF film and 12 uF electrolytic for improved sound, while maintaining tonal balance. I could have used all film and added a resistor to keep ESR the same, but went for the simpler route.
    2. Replaced clips to drivers with soldered connections.
    3. Replaced internal wiring
    4. Added felt diffraction pads around tweeters. They're actually furniture pads inexpensively purchased at Lowe's. That required expanding the openings in the grills, but I usually run them without.

    [​IMG]
     

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