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Models with indication of signal level in dBµV

Discussion in 'Tuners' started by xkdb, Oct 23, 2018.

  1. xkdb

    xkdb New Member

    Messages:
    7
    Indeed, that seems to be the case, so RF energy in the band with wider IF filter settings affects the reading. I consider it a cheap solution, which I want to avoid, so if I decide that I would settle with a HiFi unit, I would check it for that in more detail (perhaps I should have mentioned that as well). I think the dynamic range of the log amp doesn't go past roughly 70dBµV for most units, including SA5ES (and of course the meter reads less as the attenuation is activated). Hitachi explicitly mention that in FT-5500's service manual. However, more expensive builds, and particularly professional monitoring/re-broadcast receivers include a dedicated meter circuit, with a range of up to 100–120 dBµV, as you pointed out. This might also be the case with JVC FX-1010, except for the range (it's claimed that the meter circuit takes a lot of space and is quite accurate). However, I haven't checked the schematics, so I might be wrong about this.

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    I understand most listeners' accent on taste. However, this criteria for evaluation of audio sources works inside one's own world or friendly circle. Some people, predicated on taste or conditioned perception, insist that a reasonably good cassette deck and tape recording just sound better than a high-quality digital source, despite the differences in ex. frequency response, and the SNR and THD differences, which measure in orders, and despite the audible wow & flutter with many tape decks. But this is not a plausible argument for putting it on a list above the digital source as 'better', except for one's own reference, of course. In fact, when people refer to a source as sounding 'analog' and prefer it as 'better', in many cases this usually implies more imperfection, losses, and coloration. There is nothing wrong with tastes, except when they are taken to imply objective 'better' and 'worse'. Detailed technical specifications aside, I tend to aurally evaluate with regards to transparency (more/less, closer to/farther from). Now, as you all know, FM programs are all processed, the audio is compressed because of the narrow dynamic range of FM, ±75kHz deviation counting the pre-emphasis in, pilot tone, etc, but useful conclusions can still be done when comparing units, with some experience in processing and aural evaluation of audio materials, very good reception for a few stations, and also knowing the original source materials used in the comparisons. If ex. unit 1 consistently performs such that it tends to alter the audio signal more than unit 2, then unit 2 is the better or more transparent one, audio-wise, even though that might not match one's taste. Having owned and listened to the Kenwood models I mentioned (KT-7020/990D, 1100SD, 3300D), on both my monitors and monitoring headphones (I have a small home studio, for self-producing and audio restoration), I cannot give them so much credit; they have a similar signature, the peculiarities of which include flatter sound stage, poorer bass resolution and highs, while in comparison ex. Yamaha T-85 does better in that regard. I thought about modifying KT-1100SD, but did not found the time and dedication, so I sold it in the end.

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    As a side note to the previous replies (probably no need to mention): When it comes to builds, weight does not necessarily translate to better electroacoustical and sonic qualities between audio units (especially when it comes to comparing different eras, for obvious reasons).

    I have seen L-1000T's internals previously, but that's not what I was referring to. Of course, inside it has the typical sophisticated build quality for a L-series unit, and it's a L-unit after all. As I said, it's an undeniably good tuner, just somewhat over-rated IMO: inoperable without the remote, no dedicated measurement circuit and too few parameters measurable for a high-end unit, somewhat plasticky design/feel; and what about the audio section? It's been a long time since I had a glance over the schematics, but I think it was quite similar to KT-1100SD/KT-3300D (might be wrong though), and I don't find these units sonically satisfactory. This is the main issue with them (unmodified) as I otherwise consider them among the strong runners reception-wise.
    Frankly, L-02T and KT-917, possibly 600T are the Kenwoods I would consider at this point.

    All in all, it seems I'll settle with a monitoring or re-broadcast receiver by 2wcom, WorldCast Systems, or DIVA, which would fit well in my audio rack.
     
    Last edited: Nov 4, 2018

     

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  2. xkdb

    xkdb New Member

    Messages:
    7
    Can anyone provide more details about Accuphase T-105? It is quite affordable in Europe and has a nice multi-purpose meter as well. I was unable to find schematics or detailed information, though. I have seen one or two claims that earlier Accuphase tuners have 'flat' sound stage and 'thin' sound. However, this might be related to old caps in the signal path as well.

    Thanks.
     
    Last edited: Nov 4, 2018
  3. PabloTincho

    PabloTincho Active Member

    Messages:
    102
    Location:
    Salt Lake City Utah
  4. Bob@FM

    Bob@FM Active Member

    Messages:
    358
    Location:
    NE NY
    On different IF bands giving different meter readings - It's not that uncommon, but usually has nothing to do with more RF energy in wider bands.
    It is due mostly to different gains used in the wide and narrow IF paths. Usually narrow filters have more loss, so those stages have more IF gain than wide stages, to make up for greater filter insertion loss.
    Many better tuners have an adjustment to equalize the gain between wide and narrow paths, so the meter reads the same in both cases. But it has to be set up correctly during alignment.

    Also it is due inconsistencies in ceramic filters (if used for both wide and narrow). They are inconsistent (for the same filter BW) in loss value, and in many cases you can have a mismatch in center frequency between wide and narrow filters.
    When filter center frequency mismatch that is evident, the alignment technician has to choose which path should be used for primary alignment with the RF stages. Of course the best solution is to rip out the filters and replace them with matched ones, but few have the ability of resources (endless supply of matched filters) to do that. So that condition can also lead to different meter readings, especially when the tuner has no provision for IF gain adjustment to make sure all IF paths read the same.

    On the "taste" thing - this can be discussed endlessly, but one persons opinion is still one persons opinion. Everyone has their own distinct impressions of "what sounds good". It can be influenced by many things, but it is well known that not everyone will always agree. So be it.
    Said another way, you can only truly be an authority as to "what sounds good" for an audience of one - yourself. People may discuss and compare impressions, and sometimes agree, or disagree. But that does not make anyone "right" or "wrong". Just different.
     

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