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Thread: Impedance Matching/Mismatch

  1. #21
    Join Date: Feb 2013

    Location: W Lothian

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    I'm Grant.

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    Does it get very loud very quickly?
    Last edited by struth; 19-04-2017 at 14:56.
    Regards,
    Grant ....
    Sometimes incompetence is useful. It helps you keep an open mind.
    .... ..... ...... ...... ................... ..... ..... ..... ..... .....
    IMUTO TAURUS X4 BATTERY SUPPLY. - RPI2B & AUDIOPHONICS DAC running MOODE 3.6- TONBRUX BATTERY SUPPLY & CHROMECAST2 AUDIO DONGLE no1 - JBE SERIES 3 SLATEDECK & EMOTIVA XPS-1 PHONO - DENON DV2900 & HEAVILY MODDED MF X10v3. BERESFORD SWITCHBOX. - TWIN PRO MONOBLOCK AMPLIFIERS. - CREEK OBH-11SE HEADPHONE AMP. -AUDIO TECHNICA ATH-MSR7 HEADPHONES - WIN10 JRIVER22, SPOTIFY PREMIUM- OPPO PM-3 PLANAR HEADPHONES, KINPS CABLES, SMSL M6 MINIDAC, CHROMECAST2 AUDIO DONGLE no2 POWERED BY ANKER BATTERY PSU - FULL RANGE TWIN & SINGLE TELEFUNKEN's - TANDBERG TCD310 - CARTS.. AT95 Shibata, SHURE M55E original, JVC MD1029. - RCA CABLES BY BRIAN SPKR CABLES BY MOI HAIR BY MARCO FEET BY ELECTRICBEACH - MAINS REGENERATED BY POWERINSPIRED AND FILTERED BY BELKIN PUREAV.

  2. #22
    Join Date: Nov 2008

    Location: Belfast/Northern Ireland/UK

    Posts: 15,643
    I'm Neil.

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    Quote Originally Posted by Simon_LDT View Post
    That's what I'm thinking to try. I don't think many passives have tape outs, from those I've seen/read about.



    I don't have many different interconnects around but I did try 4 different ones and no luck (Van Damme, Klotz MC500 and Mark Grant's Canare & G1000HD).
    I recall years ago coming across a similar issue that was solved via a cable swap, the fact you have tried several with no change shows its not that. It was a very long shot though.

    I have however had problems with kit with very high output overloading inputs which manifests in a similar way to how you described. Sometimes companies are not totally honest with their specs. First time I tried a Chord DAC 64 many years ago it overloaded the input on the amp I was using at the time. That company subsequently changed the amp design to accommodate higher output sources.

    Some modern highly compressed and loud CDs can tip things too, what is just on the edge of being ok with normal CDs can be overloaded by this type of CD.
    Regards Neil

  3. #23
    Join Date: Oct 2016

    Location: Bolton, England

    Posts: 468
    I'm Andrew.

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    Quote Originally Posted by Arkless Electronics View Post
    There is still something not right here whatever "cure" is used.... No modern amp should be overloaded by a CD player (or other digital source with 2V output) as this is the de facto "standard" input these days!
    I agree. I wonder how long the mkI version was available and why it's been superseded by the mkII. Even so, how would it even get to market if it can't handle 2V? And where in the chain is its volume control? If it was the first thing the signal encountered it would be a simple matter to turn it down to prevent overload.
    On the assumption that it's only quite small/light, maybe it wouldn't be a bad idea to send it to Jez for checking out and/or repair.

  4. #24
    Join Date: Oct 2012

    Location: NE England

    Posts: 3,812
    I'm Jez.

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    Quote Originally Posted by RothwellAudio View Post
    I agree. I wonder how long the mkI version was available and why it's been superseded by the mkII. Even so, how would it even get to market if it can't handle 2V? And where in the chain is its volume control? If it was the first thing the signal encountered it would be a simple matter to turn it down to prevent overload.
    On the assumption that it's only quite small/light, maybe it wouldn't be a bad idea to send it to Jez for checking out and/or repair.
    That's the crux of it, where's the vol control? Indeed as I suggested it should not have got to market if it can't handle the standard 2V output of the sources 90% of customers will be using with it!

    I wasn't for a moment suggesting that the op send it to me for any tests, more just a throwaway comment that as in 90% of such cases it would be dead easy and take minutes if one was present with suitable test gear to see it for ones self. If the op really wants me to check it then I can do that but would need the source as well as the headphone amp and if I found a problem I would have to modify it to suit I guess. It may be not an overload problem but a case of the headphone amp oscillating when it sees a certain source impedance or combination of that and output level. Another possibility is that the source doesn't like a capacitive load it sees in the headphone amp and oscillates.... Without an oscilloscope the op would never know.
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  5. #25
    Join Date: Aug 2011

    Location: Coventry, England UK

    Posts: 344
    I'm Simon.

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    Just to update, I'm currently using a Tisbury passive (mk2) and going through that there is no distortion either. I've got it set at 0db on the dip switches and plugged into ouput 2 which is set to looped. In my limited knowledge, I take it that it's basically acting like a tape out as it's sending the input (DAC) straight to the output, taking out the volume pot?

    I can only assume there is some kind of incompatibilty between my DAC and headphone amp (could be the oscillating maybe like you mention Jez). Very strange indeed.

  6. #26
    Join Date: Oct 2016

    Location: Bolton, England

    Posts: 468
    I'm Andrew.

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    Yes, it's strange that it works fine with the Tisbury and the other peramp, but not when the DAC goes straight to the headphone amp - the signal level should be the same in all cases.

  7. #27
    Join Date: Aug 2011

    Location: Coventry, England UK

    Posts: 344
    I'm Simon.

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    Well, well, well... Just had an interesting development. Having lived with the Tisbury a few days, I like the sound so am leaving it in place for a few weeks before switching back to the active to compare.

    Anyhow, I've been connecting up all sources and while doing so, I left a set of IC's in the 2nd output of the DAC still going into the active pre. Now, when I went to listen, there was now distortion coming through the speakers! After more fiddling with cables to see why this was suddenly happening I found that by removing the 2nd set of DAC outputs the sound returned to normal. I haven't yet re-tried the headphone amp because I am sure when I did before I still had both outputs active but I will report back when I do.

    If it turns out it's the DAC at fault, why would having IC's plugged in both outputs cause this distortion? Surely it's designed to output to both otherwise why have them? (btw, the active pre was not in use when this distortion occured).

  8. #28
    Join Date: Aug 2011

    Location: Coventry, England UK

    Posts: 344
    I'm Simon.

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    Yep, just tried the headphone amp straight from the DAC, without having the 2nd set of IC's connected and no distortion at all. Looks like it's the DAC at fault.

    Bit annoyed about this, looks like I'll have to send it back to Arcam.

    Anyone know what the problem might be?

  9. #29
    Join Date: Aug 2011

    Location: Coventry, England UK

    Posts: 344
    I'm Simon.

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    Just found this in the manual:

    ''The D33 DAC provides a pair of unbalanced audio
    outputs on standard RCA phono connectors and a set
    of balanced audio outputs on male XLR connectors. All
    audio outputs are available simultaneously, allowing
    multiple devices to receive the D33’s output signal.
    However, to maintain the cleanest possible signal path
    the pair of unbalanced outputs is not individually
    buffered. This means that if two amplifiers are
    connected, both must be powered on to avoid degrading
    the signal.''

    Could that be the issue? I shall have to try both amps on and see whether the problem goes away.

  10. #30
    Join Date: Feb 2013

    Location: W Lothian

    Posts: 32,162
    I'm Grant.

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    could wel be.. yeah try both on.
    Regards,
    Grant ....
    Sometimes incompetence is useful. It helps you keep an open mind.
    .... ..... ...... ...... ................... ..... ..... ..... ..... .....
    IMUTO TAURUS X4 BATTERY SUPPLY. - RPI2B & AUDIOPHONICS DAC running MOODE 3.6- TONBRUX BATTERY SUPPLY & CHROMECAST2 AUDIO DONGLE no1 - JBE SERIES 3 SLATEDECK & EMOTIVA XPS-1 PHONO - DENON DV2900 & HEAVILY MODDED MF X10v3. BERESFORD SWITCHBOX. - TWIN PRO MONOBLOCK AMPLIFIERS. - CREEK OBH-11SE HEADPHONE AMP. -AUDIO TECHNICA ATH-MSR7 HEADPHONES - WIN10 JRIVER22, SPOTIFY PREMIUM- OPPO PM-3 PLANAR HEADPHONES, KINPS CABLES, SMSL M6 MINIDAC, CHROMECAST2 AUDIO DONGLE no2 POWERED BY ANKER BATTERY PSU - FULL RANGE TWIN & SINGLE TELEFUNKEN's - TANDBERG TCD310 - CARTS.. AT95 Shibata, SHURE M55E original, JVC MD1029. - RCA CABLES BY BRIAN SPKR CABLES BY MOI HAIR BY MARCO FEET BY ELECTRICBEACH - MAINS REGENERATED BY POWERINSPIRED AND FILTERED BY BELKIN PUREAV.

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