Analogue bypass

Discussion in 'AV Pre-Amp/Processors & Power Amps' started by dazed&confused, Jun 22, 2015.

  1. dazed&confused

    dazed&confused
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    As my very old Yamaha receiver has decided to die, I think I'll get a basic processor/preamp. Probably something cheap secondhand to keep me going until I can decide on which direction to go, regarding source solutions longer term.

    Maybe a secondhand Arcam AV9 or something similar; maybe I'll spend a bit more and get a secondhand or ex-display Audiolab 8200AP. Tag McLaren is not an option because I need analogue inputs from my old Multi disc player; furthermore I'm likely to replace this with an Oppo 105

    I'm confused by the nature of multichannel analogue inputs. When using these inputs I would still want to implement the settings in the AV processor regarding speaker distance, speak level, crossover, and lip sync. But doesn't this involve digital processing? In which case what does analogue bypass really mean, and what's the point?

    Does the meaning of the term and the nature of its implementation vary between brands and models? How can I be sure how it works in what I buy, as it does not seem very clear from published specifications?

    Also, whilst I'm here, any suggestions for a send hand processor for me? It must be the colour silver.

    Many thanks,

    David.
     
  2. stephenbarnes

    stephenbarnes
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    Analogue bypass on multi-channel channel would either be straight bypass into the pre-amp, no speaker distance, crossover, lip sync. Perhaps levels, but sometimes not

    Some may process the multi-channel input so you can use bass management. And some may have high pass through crossover network (highly unlikely though) ie like a Outlaw ICBM-1. Some may allow you to have staight bypass, or digitise it.

    Also be aware that the Oppo LFE output runs into distortion as it goes into clipping, under certain conditions.

    I use a Lexicon MC-8 which has a 5.1 analogue input, it is a straight bypass (you are relying on the bass management at the source) you can only adjust channel level. If you want to digitise the input, you need to move to the MC-12.
     
  3. KelvinS1965

    KelvinS1965
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    Stephen is correct in the case of the AV8/9 (I have the former) and you just have levels to adjust and master volume on the analogue inputs. Since I own an Oppo player which also suffers the clipping issue, I just use 'core DTS' via coax/optical into the AV8 which gives me access to the AV8's bass management/distances, etc and avoids the clipping issue using the Oppo analogue outputs. It still sounds remarkably good this way (in fact I think it sounds better than my old Onkyo 818 and that had HD decoding).

    You don't mention what power amp you plan to use with the AV9. I take you are aware it will need one?
     
  4. dazed&confused

    dazed&confused
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    Thanks both for your helpful, informative replies.

    My multi disc player will play DVD audio and SACD but only through its multichannel outputs. It does have some speaker and bass management but this is very limited. Crossover frequency is in large (20Hz) steps and the same level is applied to all speakers. I would prefer separate crossovers for multichannel music as my PMC speakers are FB1i on the front but DB1i for surrounds. To be fair though, I imagine that a single crossover setting would be the case for all processers and players apart from quite high end ones. Unfortunately my multidisc player's speaker distance settings assume that my speakers are equidistant from left to right but because of the placement of the windows in my room the right surround is 1 m further than the left surround from the main listening point. On a plus point, speaker levels can all be set individually.

    I wonder to what extent would a newer player such as the Oppo 105 solve the problems above?

    My player has no lip sync adjustment. Does the Oppo have this? Or is it assumed that one would only ever use the multichannel outputs for audio only (SACD/DVD audio) even though the Oppo has superior DAC conversion in comparison to many older processes (and therefore should sound better for movies using analogue out)?

    Excuse my ignorance for this question, which is probably a thick one, but if I use the speaker and crossover settings in my multi disc player for multichannel analogue output then would these settings still apply when using the digital output - or would the processor override them in this mode?

    Is the distortion and clipping problem in the Oppo likely to occur when listening to multichannel music? Or just movies?

    kelvin I'm not entirely sure what court DTS is. Is it suitable for SACD and DVD audio?

    Do I have power amps? The short answer to this can of worms is yes. I will post more about this after tea.
     
  5. dazed&confused

    dazed&confused
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    So, Power amps......

    For the moment I will use my two old Cyrus smart powers at the front (one switched to mono block mode; the other in stereo mode). I also have a spare Cyrus 6vs integrated amp, which I can set to unity gain and use for the surround speakers. For stereo purposes I will bypass any AV processor by going through my Townsend Allegri "passive preamp".

    I've been thinking I would upgrade the front stereo amplification to a couple of Cyrus Mono X300. I guess I have some affection for Cyrus amps (in the loft I still have the original Cyrus 1 integrated amp, together with the invoice, which I purchased using my apprentice wages in about 1986). They also seem suitable for a few reasons

    - their half width means they can be tucked sideways, Hidden away underneath my AV table which sits in the corner at the end of a sofa
    - it's easy to mix and match them and move them around the 5.1 system as one upgrades; and fairly easy to sell on
    - The Mono X300 should be a good match for The PMC FB1i. I want lots of detail and transparency along with fluidity but also something with plenty of 'musicality' to keep the PMC speakers awake. These speakers have a lot going for them but they can tend to be rather lifeless at times.

    I'm finding my thoughts drawn to other ideas though. I've seen some references here to ATI amps and I'm wondering if they might be better value, even if buying new compare it to Second hand Cyrus Mono X300.

    Having said that, I suspect that ATI amps might have similar characteristics to Bryston amps. A couple of weeks ago I had a conversation with the head of sales from Cyrus, Who had just moved there from PMC (The company which distributes bryston in the UK). When I asked whether Briceton or Cyrus were best with PMC he said that Briceton where more accurate but that Cyrus were more enjoyable. In my set up I think my speakers need an injection of enjoyment.
     
  6. KelvinS1965

    KelvinS1965
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    I can answer some of your questions, especially re the Oppo as I (briefly) considered upgrading my Oppo 93 for a 105 earlier this year until I found out about the clipping issue.

    The 105 and 103 have lip sync adjustment for the analogue outputs, I think up to 100mS maximum. I think the speaker distances are still in 'pairs' though a quick check of the manual would confirm this, the dB levels can be individually set though which should help in your case. Most processors and even quite budget AVRs allow crossovers to be set by pairs rather than globally (ie L/R, centre, L/R surround & L/R surround back), so it's only older AV processors like my AV8 that only allow global.

    There are arguments for using the same crossover all round, I can't remember the details off hand, but it also helps if you have near identical speakers all round which isn't the case in your set up (I used to have TB2+ fronts and Wafer 1 surrounds myself FWIW).

    The speaker/crossover settings in the player aren't applicable using the digital outputs, so these would need to be set in the AV processor/AVR. The clipping issue started a massive thread on AVS forum and there were still some people saying that it didn't matter and it was more down to the discs not being mastered correctly. However it does seem that when using 'small' speaker setting for the speakers then the headroom in the LFE channel can be used up sooner than it should be, so in some cases there will be clipping if there is a lot of bass in the other channels and the LFE at the same time. Since the 105 is a significant investment I decided that I would just continue to use my 93 via coax output and instead I spent that money on a Dirac live eq unit (miniDSP DDRC-88A).

    'Core DTS' is the basic part of a BluRay sound track. It is a higher bitrate than DVD (1.5mbps compared to around 500kbps) so it is much less compressed than DVD. If your amp/player can't decode the HD extension which is sort of 'hidden' in the sound track, then at least you get this higher bit rate audio compared to DVD. It doesn't apply to SACD or DVD audio however.

    I can't help too much wrt power amps, just wanted to make sure that you realised you'd need one (sorry if it seems patronising/teaching you to suck eggs). I'm using an Arcam P7 myself which I've just had repaired/refurbished but I've not had much chance to sit and listen to it as I didn't have the AV8 when the P7 went in for repair. Initially it does seem to be more neutral than the slightly warmer sound when I was temporarily using an old Denon AVR in bypass as a 'power amp', so there are differences in the sound of power amps for sure.

    My DDRC-88A allows me to create custom target curves for the room eq (4 memories) so I can tweak the sound to a degree, though I prefer a more 'purist' approach for music and limit the eq to below 300Hz for stereo listening. However I'm not using PMC speakers these days as I'm more centred on films so I changed for a set of MK Sound MP150/S150T and built two 15" sealed subs.
     
  7. stephenbarnes

    stephenbarnes
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    ATI amps aren't cheap, although I suppose compared to Bryston, Classe, Krell, they are. They have just gone up in price.

    If you want the most affordable multi-channel model that would be 1800 series, 1805 is 5 channel, 180W per channel, 1807 is 7 channel (same power)

    If you don't need tons of power but you want lots of channels there's the 12 channel 6012 which is 60W per channel

    I use two ATI 2000 series to get 7 channels.
     
  8. dazed&confused

    dazed&confused
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    Many thanks Stephen and Kelvin for taking the trouble to reply again to my questions - sorry to take so long to respond.

    So – I decided to break out the credit card and I have ordered a brand-new Audiolab 8200AP from Frank Harvey. I'm not entirely sure it's the best solution but hey ho.

    I spoke to David at Frank Harvey (he owns the same processor) and to a guy at IAG, and it seems that there is some degree of speaker setting control in analogue bypass mode. I also asked IAG whether the volume control is analogue or digital and the guy said digital - this doesn't seem ideal to my mind, but I guess my ears shall see ;-)

    One of the reasons I went for the Audiolab rather than a second hand older processor is its HDMI ability. If I ever venture into this room correction malarkey then I'd like to have the option of a mini DSP using HDMI in and out (which as it happens, I'm told, the mini DSP can only do for a PCM Signal). I didn't want the full blown DRRC-88A solution to be the only option in my set up, especially if I get an Oppo 105. It would seem a waste to pay Oppo the extra money for superior analog output only to convert the signal back to digital again.

    I would have liked a processor that could do automatic lip sync but I figure that this requires video processing within the processor. Again, I couldn't see the point of paying for an expensive Blu-ray player only to reprocess the video signal. And I have doubts about the success of automatic lip sync. Nevertheless, I do find trying to do it manually to be a great pain in the arse.

    I take your point about having matching speakers all around the room, Kelvin. In my case though, the surround speakers have to be hung on the wall. I was quite surprised by a conversation I had at a recent PMC Cyrus demonstration day. I said I was thinking of upgrading from FB1i to OBi Front speakers and the guy from PMC said the advantages of moving to Twenty.26 would far outweigh any problems caused by having to retain i series speakers for surrounds. He said the match should still be fine because Peter Thomas had done the voicing for both series of speakers.

    Thanks Kelvin for telling me about Core DTS. It will be interesting for me to compare this via coax/Toshlink to HD audio via HDMI, as I have read about Jitter problems regarding HDMI.
     
  9. dazed&confused

    dazed&confused
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    Thanks for the info about the amps Stephen.

    You're right that ATI amps are expensive but I guess I was thinking that my next amps will be lasting me 20 years. Two channels of Cyrus Mono X 300 cost secondhand between about £2200 and £3500, depending on whether or not they are Signature models.

    Then again who knows, regarding the 20 year outlook? Maybe there will soon be advances in technology (e.g class D with built in speaker matching) at a price that will walk all over current AB designs.

    I read a little of the L sound website and I am left with the impression that ATI amps are only really worth the expense of the higher models if one can take advantage of their balance design. Obviously my Townsend Allegri cannot do this and I seem to remember you (or another member) writing in an old post that AV processors with a true balanced design are very rare and very expensive.

    Stephen did you notice a vast improvement going from your audiolab amps to the ATI ones?
     
  10. stephenbarnes

    stephenbarnes
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    The Audiolab is a bit too cut down AV pre, I don't think it does onboard Master/HD decoding? It's a bit lacking in HDMI inputs as well. Ok for optical/coaxial as once you go HDMI then that means freeing up legacy digital input, so seems to have plenty for myself.

    I understand hardly anyone needs Marantz 8802 connectivity, but I'd want something a bit more, something like Nakamichi AV1 is ideal (again maybe couple more hdmi/optical/coax)

    As for ATI versus Audiolab sound, my room isn't ideal setup and since not doing it blind, and I know which is connected, hard to say. I find it hard to compare power amplifiers for sound quality.

    Maybe they do but it's not huge, ie comparing one integrated to another integrated, or one speaker to another speaker.

    Not using balanced, I could have gone for ATI 1803 and 1804, for far less but I didn't like how hot the 1807 got, and I read the 18 series got hotter than 2000. It was chucking out fair bit of heat. This was even in idle, and low volumes. Maybe also because the modules are so closely packed together.
     

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