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Audio and Video Talk
Valves / Vacuum Tubes
LUXMAN MQ70 tube amplifier (new issue)
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<blockquote data-quote="Ampdog" data-source="post: 960981" data-attributes="member: 144"><p>Charles,</p><p></p><p>Obviously! The models that came my way (>1 year apart) were both the same, marked MQ70. They corresponded to the schematics shown here in earlier posts.</p><p></p><p>I was not aware of a second M70, neither could I find any reference to it on the internet. Although surprised that two different amplifiers will be marked the same number (as Doug Self said: 'Anything is possible these days ...'), I also did not pick up on different M70 models on other forums that I frequented at the time (Diy-audio, Audiokarma and Audioholics.)</p><p></p><p>I reread some of my commentaries then: The zener diodes in question are 1N4760A's of 68V. Then another malady of this amplifier was pointed out by another member, viz. that the heater-cathode voltage of the ECC85 was exceeded: around 150V; spec. +or -90V max. This lead to noise and final demise of some ECC85s. (Other posts were offered; if of interest they can be googled.)</p><p></p><p>I'm am not here to bash any particular amplifier brand, just warning where warning is due. I have also not yet located my file on this work; speaking off-the-cuff as it were. (I will rummage through my files when the temperature in Pretoria is more favourable for activity!) </p><p></p><p>If someone can enlighten us to the alternative MQ70, it should be of value. (Might be that the mentioned shortcomings were improved on in a later model?)</p></blockquote><p></p>
[QUOTE="Ampdog, post: 960981, member: 144"] Charles, Obviously! The models that came my way (>1 year apart) were both the same, marked MQ70. They corresponded to the schematics shown here in earlier posts. I was not aware of a second M70, neither could I find any reference to it on the internet. Although surprised that two different amplifiers will be marked the same number (as Doug Self said: 'Anything is possible these days ...'), I also did not pick up on different M70 models on other forums that I frequented at the time (Diy-audio, Audiokarma and Audioholics.) I reread some of my commentaries then: The zener diodes in question are 1N4760A's of 68V. Then another malady of this amplifier was pointed out by another member, viz. that the heater-cathode voltage of the ECC85 was exceeded: around 150V; spec. +or -90V max. This lead to noise and final demise of some ECC85s. (Other posts were offered; if of interest they can be googled.) I'm am not here to bash any particular amplifier brand, just warning where warning is due. I have also not yet located my file on this work; speaking off-the-cuff as it were. (I will rummage through my files when the temperature in Pretoria is more favourable for activity!) If someone can enlighten us to the alternative MQ70, it should be of value. (Might be that the mentioned shortcomings were improved on in a later model?) [/QUOTE]
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Audio and Video Talk
Valves / Vacuum Tubes
LUXMAN MQ70 tube amplifier (new issue)
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