Isolation transformer on studio monitors? - Page 1
Forum section: electronics / projects

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: November 14, 2019, 06:33:01 pm
content: I would like to connect my studio monitors to isolation transformers to prevent any ground loops from occurring as I've heard them buzzing in the past on some occasions.My question is whether or not that could deteriorate their sound quality somehow. I know there will be a lower PF as this is now an inductive load from the the mains but is there any reason I shouldn't do it?

author: dom0
author_rank: Super Contributor
timestamp: November 14, 2019, 09:07:03 pm
content: Intense buzzing in bursts is GSM interference and will never be fixed by isolation transformers.QuoteNo, unless the transformers are too small for the monitors. Then it might cause excessive ripple in the monitor's power supply under load.

author: Gyro
author_rank: Super Contributor
timestamp: November 14, 2019, 09:38:55 pm
content: Also compare the cost of audio signal level isolation transformers - but check the frequency response and impedance specs very carefully, otherwise theywilldegrade sound quality.

author: Audioguru again
author_rank: Regular Contributor
timestamp: November 14, 2019, 11:35:41 pm
content: Of course an audio coupling transformer will cut and distort low frequencies, mid frequencies and high frequencies like a 60 years old guitar vacuum tubes amplifier.It also ruins the excellent damping factor of a modern amplifier.

author: David Hess
author_rank: Super Contributor
timestamp: November 15, 2019, 03:58:25 pm
content: A power line isolation transformer used with an amplifier studio monitor will have no effect on the audio quality unless something is drastically broken.But don't your amplified studio monitors have balanced inputs? They should have considerable common mode rejection which makes your problem seem more like an radio frequency interference issue.Quote from: Audioguru again on November 14, 2019, 11:35:41 pmThose limitations do not apply at small signal levels. Dampening is irrelevant into the high impedance input of an amplified studio monitor and a small signal audio transformer can cover the entire audio band with low distortion and loss although they are $50+ expensive.

author: Giaime
author_rank: Regular Contributor
timestamp: November 15, 2019, 04:08:05 pm
content: Quote from: drummerdimitri on November 14, 2019, 06:33:01 pmIf you mean an insolation transformer on the MAINS, it will do nothing for the ground loops. Unless if you cut the EARTH connection, which you shouldn't do for safety reasons.The best way would be using SIGNAL isolation transformers, on the audio lines.Usually balanced connection* will solve this anyway.Are you using the internal sound card of the PC?* Unbalanced to Balanced adapter is not a balanced connection: a balanced connection is a real balanced source, a balanced cable, a real balanced reciver.

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: November 15, 2019, 09:32:25 pm
content: I have no earth connection and yes I am talking about a mains isolation transformer.The speakers are rated at 230 W so a 500 VA isolation transformer should be enough correct?

author: David Hess
author_rank: Super Contributor
timestamp: November 16, 2019, 02:45:53 am
content: Quote from: drummerdimitri on November 15, 2019, 09:32:25 pmYes, that will be more than large enough. The speaker rating is a maximum rating and average power levels are much lower.

author: langwadt
author_rank: Super Contributor
timestamp: November 16, 2019, 03:24:24 am
content: Quote from: drummerdimitri on November 15, 2019, 09:32:25 pmmakes no sense, the speakers already have an isolated supply inside

author: Al3579
author_rank: Newbie
timestamp: November 20, 2019, 09:05:05 am
content: should need it especially if your using balanced cables. A balanced cable signal cable will have a twisted pair and ground and can be on xlr or TRS 1/4". What most people end up doing is using unbalanced TS 1/4" cables or use the unbalanced inputs.Then there is manufacturers that produce equipment with pseudo balanced inputs.with short cables runs unbalanced is usually sufficient unless you living in ground loop hell.

author: Electro Detective
author_rank: Super Contributor
timestamp: November 20, 2019, 10:03:15 am
content: There are different combinations of mains isolation transformer wiring, I would suggest trying the stock standard wiring first,before doing any dangerous earth/ground cutsIf that's a fail, then it's time to try a pair of input signal transformersIf that's a fail, then the electronics in the active/powered/amplified monitors need attentionand yes some Ground Loop Hell may be at play here toofwiw before doing any of the above, check and test ALL the signal cables FIRST, in a medieval fashion if necessary,i.e. pull the lot out and start plugging till you hear the offending racket