+ Reply to Thread
Page 1 of 6 123 ... LastLast
Results 1 to 10 of 56

Thread: Impedance Matching/Mismatch

  1. #1
    Join Date: Aug 2011

    Location: Coventry, England UK

    Posts: 346
    I'm Simon.

    Default Impedance Matching/Mismatch

    I'm currently trying to understand Impedance matching and I'm a bit stuck on a few things. I've been trying to connect my headphone amp to the outputs on my DAC, but when I do I get distortion which sounds like something overloading. In the meantime, I've just placed my pre-amp in between (connecting the tape out to the headphone amp) but I'd like to remove it from the chain if possible.

    Headphone amp is a Schiit Asgard and I was told by one of the engineers that it has an input impedance of 100k ohm. My DAC is an Arcam D33 and the manual states it has an output impedance of 47 ohm. From my understanding, it seems this should be okay as the amp has a higher impedance. My Arcam pre is a C31 and the manual says it has <50 ohm output impedance. Any reason as to why it works fine with the pre in the chain but not without it?

    My other query is regarding passives. I'd like to try one but I'm not sure if my amp would match well. My amps have a quoted input impedance of 22k ohm, is that high enough for a passive?

  2. #2
    Join Date: Feb 2013

    Location: W Lothian

    Posts: 32,187
    I'm Grant.

    Default

    more likely just to much gain from dac for head inputs
    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.

  3. #3
    Join Date: Aug 2011

    Location: Coventry, England UK

    Posts: 346
    I'm Simon.

    Default

    Would some kind of attenuation between DAC and Headphone amp fix this? If so, would that degrade the sound?

  4. #4
    Join Date: Feb 2013

    Location: W Lothian

    Posts: 32,187
    I'm Grant.

    Default

    you would be best seeing what output voltage is from dac and see iff its acceptable to the headamp.might need a bit of attenuation and im not a fan of external attenuators
    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.

  5. #5
    Join Date: Oct 2016

    Location: Bolton, England

    Posts: 468
    I'm Andrew.

    Default

    Quote Originally Posted by struth View Post
    more likely just to much gain from dac for head inputs
    Well, too high a signal from the DAC would be more accurate as DACs don't really have gain, but essentially yes. Still, you would expect a headphone amp to be able to cope with the output from a DAC without overloading.

    Quote Originally Posted by Simon_LDT View Post
    Would some kind of attenuation between DAC and Headphone amp fix this? If so, would that degrade the sound?
    Yes, attenuators would fix this. No, there won't be any degradation of the sound - it's overloading as it is!

    http://www.rothwellaudioproducts.co....tenuators.html

  6. #6
    Join Date: Oct 2016

    Location: Bolton, England

    Posts: 468
    I'm Andrew.

    Default

    Quote Originally Posted by Simon_LDT View Post
    I'm currently trying to understand Impedance matching and I'm a bit stuck on a few things.
    The source impedance (also known as the output impedance) should be a lot lower than the load impedance (aka the input impedance), preferably by a factor of 10 or more. The 100k input impedance of your headphone amp should be fine with any source up to 10k output impedance. In practice you'll find that almost everything these days has a much lower output impedance than 10k.

    Quote Originally Posted by Simon_LDT View Post
    Any reason as to why it works fine with the pre in the chain but not without it?
    Not that I'm aware of.

    Quote Originally Posted by Simon_LDT View Post
    My other query is regarding passives. I'd like to try one but I'm not sure if my amp would match well. My amps have a quoted input impedance of 22k ohm, is that high enough for a passive?
    Higher than 22k would be nice but you'll ok. A pot impedance of 10k would be about right but I wouldn't go higher than 10k.

  7. #7
    Join Date: Oct 2012

    Location: NE England

    Posts: 3,844
    I'm Jez.

    Default

    There's no such thing as impedance matching in the context of hi fi. The matching of SUT's to cartridges is about as close as we get... It is a concept used mainly in RF circuitry. Even the term impedance is usually not strictly correct unless one wishes to be really pedantic as resistance is usually more apt a term. As Andrew says, all you really need is for the driving impedance to be much higher than the input impedance.

    For the op I would check if the DAC has a selectable output level and can be turned down. Unlikely in the case of the Arcam but many pro DACs can have a higher output level selected.
    Arkless Electronics-Engineered to be better. Tel. 01670 530674 (after 1pm)

    Modded Thorens TD150, Audio Technica AT-1005 MkII, Technics EPC-300MC, Arkless Hybrid MC phono stage, Arkless passive pre, Arkless 50WPC Class A SS power amp, (or) Arkless modded Leak Stereo 20, Modded Kef Reference 105/3's
    ReVox PR99, Studer B62, Ferrograph Series 7, Tandberg TCD440, Hitachi FT-5500MkI, also FT-5500MkII
    Digital: Yamaha CDR-HD1500 (Digital Swiss army knife-CD recorder, player, hard drive, DAC and ADC in one), PC files via 24/96 sound card and SPDIF, modded Philips CD850, modded Philips CD104, modded DPA Little Bit DAC. Sennheiser HD580 cans with Arkless Headphone amp.
    Cables- free interconnects that come with CD players, mains leads from B&Q, dead kettles etc, extension leads from Tesco

  8. #8
    Join Date: Oct 2016

    Location: Bolton, England

    Posts: 468
    I'm Andrew.

    Default

    Quote Originally Posted by Simon_LDT View Post
    Headphone amp is a Schiit Asgard...
    Is it a mkI or a mkII? According to this page http://schiit.com/products/asgard-2 the mkII has "significantly improved performance". Maybe the mkI was a load of schiit

  9. #9
    Join Date: Aug 2011

    Location: Coventry, England UK

    Posts: 346
    I'm Simon.

    Default

    Thanks for the input Andrew, Jez.

    It's the mark 1 I have of the Asgard (some said it was better than the mark 2 and vice versa - If I remember correctly I got it from a fellow member here).

    I assume the pre-amp is somehow lowering/making the output signal from the DAC acceptable somehow which could be why it's fine when going through it? The DAC has a 2.2v output, no idea on what the Asgard can accept voltage-wise, maybe I should ask.

    Would a passive pre solve this at all (I would assume not with there being no active circuitry but I'm not really sure)?

  10. #10
    Join Date: Oct 2012

    Location: NE England

    Posts: 3,844
    I'm Jez.

    Default

    It would appear that you have a pretty weird issue going on here. Any headphone amp is going to be designed to take the standard 2V output of domestic digital sources these days. A quick look at the specs for your headphone amp suggest a gain switch on the rear panel which you could try using.
    A passive pre or in line attenuator (electrically identical) should solve the problem if it's overload related but as I said there should be no issue here.
    Arkless Electronics-Engineered to be better. Tel. 01670 530674 (after 1pm)

    Modded Thorens TD150, Audio Technica AT-1005 MkII, Technics EPC-300MC, Arkless Hybrid MC phono stage, Arkless passive pre, Arkless 50WPC Class A SS power amp, (or) Arkless modded Leak Stereo 20, Modded Kef Reference 105/3's
    ReVox PR99, Studer B62, Ferrograph Series 7, Tandberg TCD440, Hitachi FT-5500MkI, also FT-5500MkII
    Digital: Yamaha CDR-HD1500 (Digital Swiss army knife-CD recorder, player, hard drive, DAC and ADC in one), PC files via 24/96 sound card and SPDIF, modded Philips CD850, modded Philips CD104, modded DPA Little Bit DAC. Sennheiser HD580 cans with Arkless Headphone amp.
    Cables- free interconnects that come with CD players, mains leads from B&Q, dead kettles etc, extension leads from Tesco

+ Reply to Thread
Page 1 of 6 123 ... LastLast



 

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •