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Re: Quad current dumper amplifiers

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  • Robert
    You were lucky. I think these problems were very common. REG
    Message 1 of 72 , Aug 27, 2013
      You were lucky. I think these
      problems were very common.

      REG

      --- In regsaudioforum@yahoogroups.com, "tonycdk" <tcdk@...> wrote:
      >
      > I had not heard about the issues that you raise - I certainly never experienced them myself. In fact, I had two pairs of ESL63s for many years and never experienced problems of any kind with them.
      >
      > Apart from the overdriving issue the only other significant issue of which I am aware is related to high humidity environments.
      >
      > Tony
      >
      >
      >
      >
      > --- In regsaudioforum@yahoogroups.com, "Robert" <regtas43@> wrote:
      > >
      > > I am not all that familiar wiht the reliability
      > > issues of the current Quad line.
      > > But the older 63 model and spinoffs thereof
      > > had serious issues not related to overdriving the
      > > speakers. (I do not play things all that
      > > loudly and never injured the speakers by
      > > driving them too hard). They would for example
      > > start to buzz if the weather was bad --room too cold.
      > > I and several people I knew took to putting
      > > heaters by them to keep this under control.
      > > We are not speaking of cold cold cold--just
      > > low house temeratures, the mid 60s over night say.
      > > Then after a while, the buzz would become
      > > uncontrollable by heating the speaker up or
      > > any other way.
      > > Some sort of voltage leakng. I am not sure what sort.
      > > Current models have failed my friends in various
      > > ways.
      > > I really do not think one can make much case
      > > that the speakers are high reliability.
      > > Traditionally this hardly mattered since
      > > Quad stood so solidly behind their products.
      > >
      > > Today, I could not say from experience what
      > > would happen if the speakers went out. I just
      > > do not know, But I would surely try to find
      > > out before I put up the money.
      > >
      > > It used to be not just a question of not overdriving them--
      > > not at all.
      > >
      > > REG
      > >
      > > --- In regsaudioforum@yahoogroups.com, "tonycdk" <tcdk@> wrote:
      > > >
      > > > At 40 V peak (assuming sine wave) the QUAD will give 106 dB at 1 metre.
      > > >
      > > > 10 V rms continuous is equivalent to about 11 W continuous power - presumably enough to cause unwanted heating on a PC board. This would probably fry some coil drive units after a while as well (particularly tweeters).
      > > >
      > > > Tony
      > > >
      > > > --- In regsaudioforum@yahoogroups.com, Tom Mallin <tmallin4@> wrote:
      > > > >
      > > > > I realize the frequency dependency of what a full-range electrostat like the Quad can take in terms of input and what it can cleanly dish out in terms of output. All speakers are frequency dependent in terms of distortion at a particular SPL.
      > > > >
      > > > > But can I get some dB figures for the Quads operated full range without any EQ applied? The newest 2812 model is indeed specified to have a sensitivity of 86 dB/watt/meter, and that would typically be at 1 kHz. Surely, given the Quad's impedance, this can be translated to a maximum SPL at 1 kHz with a 40-volt input. I just don't know the formula. The current specs also say that maximum continuous RMS input is 10 volts, with the 40-volt being maximum programme input, whatever that means.
      > > > >
      > > > > Maybe this is not so important above 50 Hz, though. The current specs say that at 100 dB SPL, the distortion at 50 Hz is less than 1%. That's equivalent to dynamic drivers. Below that frequency, who knows, but at least it is good for loud playback if rolled off below that. Above 50 Hz, the distortion specs at 100 dB are much better, probably better than most dynamic drivers, .5% above 100 Hz and .15% above 1kHz.
      > > > >
      > > > > On Aug 23, 2013, at 9:36 PM, "tonycdk" <tcdk@> wrote:
      > > > >
      > > > > >
      > > > > >
      > > > > > --- In regsaudioforum@yahoogroups.com, "djanszen1" <hmaneuver@> wrote:
      > > > > > >
      > > > > > >
      > > > > > > Tom, you've nicely illustrated a specification problem of many ESL makers. The engineers know that their ESL designs have a maximum tolerable voltage, and that is good enough for them, because to them, the chain of implications is obvious.
      > > > > > >
      > > > > > > Few actual or prospective owners, however, are prepared to translate Volts into a meaningful sound level, which involves knowing several other factors and how to apply them. For those who notice the voltage rating, what it mostly does is create anxiety, or the tendency to just go for it, or both, depending on the owner's personality, leaving some portion of owners listening at disappointingly low levels and another portion causing damage.
      > > > > > >
      > > > > >
      > > > > > It is fairly easy to be safe and yet have adequate volume capability. I adjust filter gains in my room correction processing to get adequate levels and then clip the output at full-scale for any very occasional extremely large peaks. My amplifiers are set so that full-scale digital input results in a safe output voltage. Clipping is inaudible unless it happens very often.
      > > > > > ----------------------------------------------------------
      > > > > >
      > > > > > > Anyway, it would be helpful to most people if those manufacturers who specify maximum voltages would publish measurements of peak loudness at those voltages, and particularly in the cases of dipoles, bipoles, and very wide dispersion speakers, doing so in a few typical setup situations, since loudness is more a function of setup and room characteristics for these types.
      > > > > > >
      > > > > >
      > > > > > Most ES manufacturers do specify a dB/volt at 1 metre type of specification - as do coil speaker manufacturers. The major real differences relate to the time constant for 'failure'.
      > > > > > ----------------------------------------------------------
      > > > > >
      > > > > > > Even better would be to provide a peak allowable amplifier wattage specification instead of maximum allowable voltage, so no one has to determine what maximum voltage their amplifiers are putting out, and a sound level when such an amplifier is starting to clip.
      > > > > > >
      > > > > >
      > > > > > This would be a frequency dependent issue for all speaker types as impedance is typically a function of frequency and the amplifier wattage always is based upon a particular impedance - usually something like X Watts into 8 Ohms.
      > > > > >
      > > > > > ----------------------------------------------------------
      > > > > >
      > > > > > > Better yet is to make the speakers immune to overvoltages, but just not sound right when it happens, and not risk harm to the amplifiers in the process.
      > > > > > >
      > > > > >
      > > > > > This is something that QUAD have tried to do but there is no real solution for stupidity.
      > > > > >
      > > > > > Tony
      > > > > > ----------------------------------------------------------
      > > > > >
      > > > > > > Best, build the amplifiers in. But how reasonable is that, trusting a speaker manufacturer to know something about amplifiers and sound? Yes, I know that's not the main issue.
      > > > > > >
      > > > > > > --- In regsaudioforum@yahoogroups.com, Tom Mallin <tmallin4@> wrote:
      > > > > > > >
      > > > > > > > Tony, Quad is the only speaker manufacturer I've ever seen specify the
      > > > > > > > maximum input in terms of volts. There also is no spec in terms of maximum
      > > > > > > > safe output. Could you please translate the 40 and 50 volt spec into dB
      > > > > > > > out at 1 kHz at one meter, with one speaker playing? Thanks much.
      > > > > > >
      > > > > >
      > > > > >
      > > > >
      > > >
      > >
      >
    • Robert
      You were lucky. I think these problems were very common. REG
      Message 72 of 72 , Aug 27, 2013
        You were lucky. I think these
        problems were very common.

        REG

        --- In regsaudioforum@yahoogroups.com, "tonycdk" <tcdk@...> wrote:
        >
        > I had not heard about the issues that you raise - I certainly never experienced them myself. In fact, I had two pairs of ESL63s for many years and never experienced problems of any kind with them.
        >
        > Apart from the overdriving issue the only other significant issue of which I am aware is related to high humidity environments.
        >
        > Tony
        >
        >
        >
        >
        > --- In regsaudioforum@yahoogroups.com, "Robert" <regtas43@> wrote:
        > >
        > > I am not all that familiar wiht the reliability
        > > issues of the current Quad line.
        > > But the older 63 model and spinoffs thereof
        > > had serious issues not related to overdriving the
        > > speakers. (I do not play things all that
        > > loudly and never injured the speakers by
        > > driving them too hard). They would for example
        > > start to buzz if the weather was bad --room too cold.
        > > I and several people I knew took to putting
        > > heaters by them to keep this under control.
        > > We are not speaking of cold cold cold--just
        > > low house temeratures, the mid 60s over night say.
        > > Then after a while, the buzz would become
        > > uncontrollable by heating the speaker up or
        > > any other way.
        > > Some sort of voltage leakng. I am not sure what sort.
        > > Current models have failed my friends in various
        > > ways.
        > > I really do not think one can make much case
        > > that the speakers are high reliability.
        > > Traditionally this hardly mattered since
        > > Quad stood so solidly behind their products.
        > >
        > > Today, I could not say from experience what
        > > would happen if the speakers went out. I just
        > > do not know, But I would surely try to find
        > > out before I put up the money.
        > >
        > > It used to be not just a question of not overdriving them--
        > > not at all.
        > >
        > > REG
        > >
        > > --- In regsaudioforum@yahoogroups.com, "tonycdk" <tcdk@> wrote:
        > > >
        > > > At 40 V peak (assuming sine wave) the QUAD will give 106 dB at 1 metre.
        > > >
        > > > 10 V rms continuous is equivalent to about 11 W continuous power - presumably enough to cause unwanted heating on a PC board. This would probably fry some coil drive units after a while as well (particularly tweeters).
        > > >
        > > > Tony
        > > >
        > > > --- In regsaudioforum@yahoogroups.com, Tom Mallin <tmallin4@> wrote:
        > > > >
        > > > > I realize the frequency dependency of what a full-range electrostat like the Quad can take in terms of input and what it can cleanly dish out in terms of output. All speakers are frequency dependent in terms of distortion at a particular SPL.
        > > > >
        > > > > But can I get some dB figures for the Quads operated full range without any EQ applied? The newest 2812 model is indeed specified to have a sensitivity of 86 dB/watt/meter, and that would typically be at 1 kHz. Surely, given the Quad's impedance, this can be translated to a maximum SPL at 1 kHz with a 40-volt input. I just don't know the formula. The current specs also say that maximum continuous RMS input is 10 volts, with the 40-volt being maximum programme input, whatever that means.
        > > > >
        > > > > Maybe this is not so important above 50 Hz, though. The current specs say that at 100 dB SPL, the distortion at 50 Hz is less than 1%. That's equivalent to dynamic drivers. Below that frequency, who knows, but at least it is good for loud playback if rolled off below that. Above 50 Hz, the distortion specs at 100 dB are much better, probably better than most dynamic drivers, .5% above 100 Hz and .15% above 1kHz.
        > > > >
        > > > > On Aug 23, 2013, at 9:36 PM, "tonycdk" <tcdk@> wrote:
        > > > >
        > > > > >
        > > > > >
        > > > > > --- In regsaudioforum@yahoogroups.com, "djanszen1" <hmaneuver@> wrote:
        > > > > > >
        > > > > > >
        > > > > > > Tom, you've nicely illustrated a specification problem of many ESL makers. The engineers know that their ESL designs have a maximum tolerable voltage, and that is good enough for them, because to them, the chain of implications is obvious.
        > > > > > >
        > > > > > > Few actual or prospective owners, however, are prepared to translate Volts into a meaningful sound level, which involves knowing several other factors and how to apply them. For those who notice the voltage rating, what it mostly does is create anxiety, or the tendency to just go for it, or both, depending on the owner's personality, leaving some portion of owners listening at disappointingly low levels and another portion causing damage.
        > > > > > >
        > > > > >
        > > > > > It is fairly easy to be safe and yet have adequate volume capability. I adjust filter gains in my room correction processing to get adequate levels and then clip the output at full-scale for any very occasional extremely large peaks. My amplifiers are set so that full-scale digital input results in a safe output voltage. Clipping is inaudible unless it happens very often.
        > > > > > ----------------------------------------------------------
        > > > > >
        > > > > > > Anyway, it would be helpful to most people if those manufacturers who specify maximum voltages would publish measurements of peak loudness at those voltages, and particularly in the cases of dipoles, bipoles, and very wide dispersion speakers, doing so in a few typical setup situations, since loudness is more a function of setup and room characteristics for these types.
        > > > > > >
        > > > > >
        > > > > > Most ES manufacturers do specify a dB/volt at 1 metre type of specification - as do coil speaker manufacturers. The major real differences relate to the time constant for 'failure'.
        > > > > > ----------------------------------------------------------
        > > > > >
        > > > > > > Even better would be to provide a peak allowable amplifier wattage specification instead of maximum allowable voltage, so no one has to determine what maximum voltage their amplifiers are putting out, and a sound level when such an amplifier is starting to clip.
        > > > > > >
        > > > > >
        > > > > > This would be a frequency dependent issue for all speaker types as impedance is typically a function of frequency and the amplifier wattage always is based upon a particular impedance - usually something like X Watts into 8 Ohms.
        > > > > >
        > > > > > ----------------------------------------------------------
        > > > > >
        > > > > > > Better yet is to make the speakers immune to overvoltages, but just not sound right when it happens, and not risk harm to the amplifiers in the process.
        > > > > > >
        > > > > >
        > > > > > This is something that QUAD have tried to do but there is no real solution for stupidity.
        > > > > >
        > > > > > Tony
        > > > > > ----------------------------------------------------------
        > > > > >
        > > > > > > Best, build the amplifiers in. But how reasonable is that, trusting a speaker manufacturer to know something about amplifiers and sound? Yes, I know that's not the main issue.
        > > > > > >
        > > > > > > --- In regsaudioforum@yahoogroups.com, Tom Mallin <tmallin4@> wrote:
        > > > > > > >
        > > > > > > > Tony, Quad is the only speaker manufacturer I've ever seen specify the
        > > > > > > > maximum input in terms of volts. There also is no spec in terms of maximum
        > > > > > > > safe output. Could you please translate the 40 and 50 volt spec into dB
        > > > > > > > out at 1 kHz at one meter, with one speaker playing? Thanks much.
        > > > > > >
        > > > > >
        > > > > >
        > > > >
        > > >
        > >
        >
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