dana
Rank: Soloist
Posts: 16
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Post by dana on Aug 26, 2023 15:20:05 GMT
Technics SA-GX690 Receiver goes into protection mode, at higher volumes only . Mirage M-3si speakers ...... what might be causing this condition, is there a procedure for trouble shooting this. TIA
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Post by Slinger on Aug 26, 2023 16:40:53 GMT
It could be as simple as poor ventilation, and the high volume causing the amp to overheat. Your speaker impedance might be outside of the manufacturer's specs. Raising the volume with a low-impedance speaker can trigger the protection circuit. I got those from Google. Manuals are here - www.manualslib.com/products/Technics-Sa-Gx690-300423.html |
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dana
Rank: Soloist
Posts: 16
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Post by dana on Aug 26, 2023 23:18:36 GMT
Hi Slinger, If I remember correctly you were saying the Mirage's are 4 ohm speakers. My Technics rec is 6 or 8 Ohm's typically. Should I try to change the output ohms to drive my speakers, I'm sorry i dont understand these values and how they effect the speaker and the receivers . I'm trying to learn in order to operate them optimally
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Post by MartinT on Aug 27, 2023 4:37:16 GMT
If the receiver is not designed for a high current 4-ohm load, it may well go into protection mode. Depends what you mean by 'higher volumes'.
As Paul says, try giving it more ventilation for cooling.
Otherwise, you'll have to accept you need a meatier amplifier capable of driving 4-ohm loads.
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Post by Slinger on Aug 27, 2023 12:24:37 GMT
I've just rediscovered a thread here, about Mirages, from ChrisB - theaudiostandard.net/post/58850/threadIt would appear that they are 6 ohms nominal, 4 ohms minimum impedance. Others, of a more technical bent than I, will understand (and hopefully explain), how that relates to your amp's speaker load impedance of 8Ω to 16Ω. When Martin refers to "Paul" btw, that's also me. He just likes to confuse people.  |
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Post by MartinT on Aug 27, 2023 12:34:29 GMT
Speaker impedance normally ranges between 4ohms and 16ohms. Very roughly, 4ohm speakers are current hungry (mine can be) while 16ohm speakers rely on greater voltage swing. The impedance is usually a complex curve, not a fixed figure, and frequently dips right in the bass area where you want the most current drive. Here's the impedance curve for your speakers:  It's pretty wicked, going lower than 4ohms at around 90Hz and lower than 6ohms at 30Hz. These speakers are going to need a lot of current drive and a receiver that's only rated for 6-8 ohms is admitting that it doesn't have a lot of current ability at low impedances. Thus the protection mode at high volumes. |
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Post by ChrisB on Aug 27, 2023 20:10:42 GMT
Yes, if you are going for high levels in perhaps a fairly big room, that amp is probably not going to like it very much. I think amps of over 100 wpc were probably most recommended for them, but, as Martin points out, ideally, you want something that's going to supply high current. The amp I use on the bass of my M3si is a 100w design but that is doubled into 4 ohms.
However, seemingly contrary to all that's been said above, my little nearly 60 year old 22 wpc Radford STA-15 valve amp drives them very nicely indeed, thank you!
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