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Post by misterc on Nov 23, 2023 19:40:21 GMT
Check the chassis ground (earth) to case and rca outer barrels see if you have continuity
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Post by jazzdad on Nov 25, 2023 11:29:39 GMT
Is the hum there when you switch the sub off? Nope only when on and is audible only at a certain volume. Tried 2 different plug outlets but still no good No the hum goes. I also checked the chassis to RCA with a multimeter and all checking out fine. So definitely not the power caps? The transformer has always buzzed when you're in close proximity which I think is normal for this size. Maybe it's just the design of the amp sending the 60hz down the speaker cable. Although it doesn't come out of the main speakers |
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Post by macca on Nov 25, 2023 11:45:34 GMT
How is the sub connected, low level or high level? Whatever, try the other option. I don't think there is any question, this is a ground loop. Swapping those caps will not solve it.
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Post by jazzdad on Nov 25, 2023 15:04:49 GMT
How is the sub connected, low level or high level? Whatever, try the other option. I don't think there is any question, this is a ground loop. Swapping those caps will not solve it. It's connected via high level. I tried the low level RCA and there was no hum |
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Post by macca on Nov 25, 2023 15:21:43 GMT
How is the sub connected, low level or high level? Whatever, try the other option. I don't think there is any question, this is a ground loop. Swapping those caps will not solve it. It's connected via high level. I tried the low level RCA and there was no hum Problem solved then. Sell those caps on to Oli.  |
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Post by jazzdad on Nov 25, 2023 15:26:55 GMT
It's connected via high level. I tried the low level RCA and there was no hum Problem solved then. Sell those caps on to Oli. 😂😂unfortunately i prefer the high level as not into home theatre. the low level sounded awful! |
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Post by macca on Nov 25, 2023 15:44:07 GMT
They should be pretty much indistinguishable - it's the exact same signal - you're sure there's not something else needs adjusting/sorting?
IME with subs for music - which admittedly isn't vast - I've preferred the low level connection.
In any case it confirms that the issue is a ground loop, there might be another way to sort it.
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Post by jazzdad on Nov 25, 2023 17:14:28 GMT
They should be pretty much indistinguishable - it's the exact same signal - you're sure there's not something else needs adjusting/sorting? IME with subs for music - which admittedly isn't vast - I've preferred the low level connection. In any case it confirms that the issue is a ground loop, there might be another way to sort it. For some reason the SVS app turns off the ability to adjust the low pass filter and is fixed at 80hz. My mains drop off around 32hz so it doesn't work out. I think there is a subwoofer grounding contraption maybe I should try that |
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Post by jazzdad on Nov 26, 2023 5:03:30 GMT
They should be pretty much indistinguishable - it's the exact same signal - you're sure there's not something else needs adjusting/sorting? IME with subs for music - which admittedly isn't vast - I've preferred the low level connection. In any case it confirms that the issue is a ground loop, there might be another way to sort it. For some reason the SVS app turns off the ability to adjust the low pass filter and is fixed at 80hz. My mains drop off around 32hz so it doesn't work out. I think there is a subwoofer grounding contraption maybe I should try that I just remembered that I swapped out the original mains cable supplied with the Parasound A21 with a Puritan Audio Classic. I can't see how this would introduce the ground issue through sub. Is it worth swapping back to the original? |
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Post by pete on Nov 26, 2023 9:26:59 GMT
No harm to rule it out as the issue
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Post by Arke on Nov 26, 2023 10:07:43 GMT
Problem solved then. Sell those caps on to Oli. 😂😂unfortunately i prefer the high level as not into home theatre. the low level sounded awful! Agreed. There is generally a noticeable difference between hi and low level on subs. My speakers have a 12" bass driver in their base and these are fed by a hi level signal (so effectively similar to stereo subs). Hi level input is noticeably taking the 'character' of the power amp in it's input signal. If I change the power amp, the measured and perceived output (of the 12" drivers) changes noticeably. |
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Post by macca on Nov 26, 2023 10:21:50 GMT
😂😂unfortunately i prefer the high level as not into home theatre. the low level sounded awful! Agreed. There is generally a noticeable difference between hi and low level on subs. My speakers have a 12" bass driver in their base and these are fed by a hi level signal (so effectively similar to stereo subs). Hi level input is noticeably taking the 'character' of the power amp in it's input signal. If I change the power amp, the measured and perceived output (of the 12" drivers) changes noticeably. well we know the reason here - the low level has a set low pass at 80hz no wonder it sounds different/bad Nothing to do with character of the power amp (or the lack of it). |
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Post by Arke on Nov 26, 2023 10:30:37 GMT
Agreed. There is generally a noticeable difference between hi and low level on subs. My speakers have a 12" bass driver in their base and these are fed by a hi level signal (so effectively similar to stereo subs). Hi level input is noticeably taking the 'character' of the power amp in it's input signal. If I change the power amp, the measured and perceived output (of the 12" drivers) changes noticeably. well we know the reason here - the low level has a set low pass at 80hz no wonder it sounds different/bad Nothing to do with character of the power amp (or the lack of it). Agreed, In the case here a fixed low pass (on low level input) is gonna make a difference. I was just making a general point that changing a power amp will make a measureable and audible difference when using different power amps on a sub hi level. I can play my speakers with 12" drivers (sub) only and the SQ difference with different power amps is very obvious. On low level the 12" drivers sound the same regardless of power amp |
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Post by jazzdad on Nov 26, 2023 21:51:05 GMT
well we know the reason here - the low level has a set low pass at 80hz no wonder it sounds different/bad Nothing to do with character of the power amp (or the lack of it). Agreed, In the case here a fixed low pass (on low level input) is gonna make a difference. I was just making a general point that changing a power amp will make a measureable and audible difference when using different power amps on a sub hi level. I can play my speakers with 12" drivers (sub) only and the SQ difference with different power amps is very obvious. On low level the 12" drivers sound the same regardless of power amp The sub has integrated amazingly well with the speaker level inputs. What speakers do you have? Always wanted to hear a set with integrated woofers of that size |
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Post by Arke on Nov 26, 2023 22:09:47 GMT
Agreed, In the case here a fixed low pass (on low level input) is gonna make a difference. I was just making a general point that changing a power amp will make a measureable and audible difference when using different power amps on a sub hi level. I can play my speakers with 12" drivers (sub) only and the SQ difference with different power amps is very obvious. On low level the 12" drivers sound the same regardless of power amp The sub has integrated amazingly well with the speaker level inputs. What speakers do you have? Always wanted to hear a set with integrated woofers of that size I have built a pair of Troels Gravesen CNO4s with a bespoke cabinet design. Build thread here: audioaddictsforum.com/thread/2585/arke-vaders-troels-gravesen-cnoHappy to demo if you ever fancy a listen. |
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