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Post by Deleted on Jul 10, 2012 21:26:44 GMT
Hi Guys, Hopefully this is in the right place . Tonight I powered up both my Mini-T amps using a LiPo battery feeding both. I tend to believe that my very first impressions on SQ are my most reliable and my first impressions on this are that the SQ is better using this battery than it is using a linear PSU fed through a JLH Ripple Eater. Might take a bit more swapping and changing to confirm but that's what I'm thinking at the moment. Certainly worth trying if you're interested, IMO. Dave. Topic moved by SandyK
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Post by Deleted on Jul 10, 2012 21:55:14 GMT
Hi Dave One thing you may accomplish by using digital amplifiers such as this with a battery supply, is to keep the often high level of HF rubbish from getting back via the mains supply into other components and degrading their performance.Try putting an AM radio near the mains lead of many digital amplifiers and see what it does to reception. Regards Alex
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Post by jeffc on Jul 11, 2012 21:13:23 GMT
to keep the often high level of HF rubbish from getting back via the mains supply into other components and degrading their performance Hi Alex/Dave, I recently replaced a bog std power cable between my SMPS powered Class D Audio amp and my AC RFI filter with a Supra mylar shielded cable, and this markedly improved SQ. Others have found the same, so back RFI from switching power supplies and amps into power supplies looks to be a culprit. Batteries I like , but just the other day I added a JLH ripple eater between a SLA battery supply and a little tube/opamp buffered amp I've been fiddling with, and this also improved SQ markedly. Once you look into it, there are big differences between battery chemistries, how they perform technically, and what they sound like. The high current LiFePO4 types seem to be terrific for audio, but their cost is a factor. cheers.. jeffc
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Post by Deleted on Jul 11, 2012 22:36:35 GMT
This applies to Computer Audio as well. Don't use the same power distribution board for the analogue components.You may even need to use a decent mains filter in line with the analogue gear , if although you are using separate power boards they are supplied from the same mains wall outlet. Regards Alex P.S. David2vk needed to use the separate mains filter for best results.
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Post by Deleted on Jul 12, 2012 20:59:22 GMT
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Post by Deleted on Jul 12, 2012 21:37:46 GMT
Hi Dave Not only does this version of the JLH reduce ripple and other noise, it has the equivalent of about 1 FARAD of capacitance, as well as typically less than 20milliohms impedance, which is lower than most batteries, but more so when you take into account the resistance of their connectors as well. Kind Regards Alex
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Post by jeffc on Jul 12, 2012 21:47:59 GMT
Hi Dave, I know next to zilch too .. Alex's info helps I hope. Have a read of these links and it should help with understanding. SLA batteries appear to make some noise under load and a fast shunt regulator can thus be of use with these. LiFePO4 probably wouldn't benifet as they'e quiet and very low impedance. www.tnt-audio.com/clinica/regulators_noise4_e.htmlwww.tnt-audio.com/clinica/regulators2_impedance1_e.htmldiyparadise.com/forum/index.php?action=printpage;topic=505.0A quote from this link ... "I use two 12V/7.5Ah SLA batteries in series and regulate it to 18V with a fast shunt regulator. I posted the circuit somewhere here. I tried other things but this sounds best to me. Batteries can be noisy and they are not as fast as some might think. NiCd are sure worse than SLA in both respects. Further regulating does improve this, but it should be done with a fast regulator. The usual three-legged 78xx won't help much." cheers.. jeffc
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Post by Deleted on Jul 13, 2012 9:09:43 GMT
Jeffc, Thanks for the links - TBH I've not read them in anydetail yet but I will.Alex, I'm inclined to try the RE between LiPo battery and Mini-T amps but my electrical non-background means that I need to ask advice to stop me doing something stupid and/or dangerous . Can you (or anyone else) tell me whether the current draw from two Mini-Ts will go through a JLH RE with or without current limiter? TIA, Dave.
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Post by Deleted on Jul 13, 2012 9:55:23 GMT
Jeffc, Thanks for the links - TBH I've not read them in anydetail yet but I will.Alex, I'm inclined to try the RE between LiPo battery and Mini-T amps but my electrical non-background means that I need to ask advice to stop me doing something stupid and/or dangerous . Can you (or anyone else) tell me whether the current draw from two Mini-Ts will go through a JLH RE with or without current limiter? TIA, Dave. Hi Dave TBH, I think you should stick with the LiPo batteries for these amps. Regards Alex
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Post by Deleted on Jul 13, 2012 10:42:52 GMT
Jeffc, Thanks for the links - TBH I've not read them in anydetail yet but I will.Alex, I'm inclined to try the RE between LiPo battery and Mini-T amps but my electrical non-background means that I need to ask advice to stop me doing something stupid and/or dangerous . Can you (or anyone else) tell me whether the current draw from two Mini-Ts will go through a JLH RE with or without current limiter? TIA, Dave. Hi Dave TBH, I think you should stick with the LiPo batteries for these amps. Regards Alex Hi Alex, Thanks for that - always happy to accept your advice but can I ask why, if there's a simple-to-understand answer? TIA, Dave
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Post by Deleted on Jul 13, 2012 11:00:13 GMT
Hi Dave First, I doubt that you would notice much difference with these particular amplifiers compared with LiPo (as distinct from more normal type batteries).Secondly, the JLH can't use it's CL section here, as it is only suitable for up to about 600mA, and the JLH should be protected from excessive inrush current draw at start up. When the CL section is not used, this is normally done by a preceeding voltage regulator. Kind Regards Alex
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Post by jeffc on Jul 13, 2012 21:10:36 GMT
Hi Dave,
Sorry to add confusion, and as Alex has clarified, those LiFePO4 batteries have such low impedance, no point adding regulation after them.
Alex, on this, I can indeed get a spark when connecting the series wire between the 12V SLA batteries to power up the JLH-tube HA. The JLH is fitted with 2 x 2200uf Suntans and no CL, so guessing the spark is due to the big inrush current. Better fit a CL, or alternatively maybe place a switch between the JLH and amp.
cheers.. jeffc
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Post by Deleted on Jul 13, 2012 21:31:45 GMT
Hi Jeff That's why I use a 12V relay at the output of the internal JLH in the PC to s/c a series 4.7 ohm 5W resistor (12V rail) at the INPUT, several hundred milliseconds after powering on.The 5V rail uses a 5V relay and series 2.2 ohm 5W resistor. Kind Regards Alex Attachments:
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