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Television Standards Converters, Modulators etc Standards converters, modulators anything else for providing signals to vintage televisions.

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Old 16th Feb 2017, 12:54 am   #1
Valve'n'vinyl
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Default TV Modulator noise ....

I have used a Maplin Universal Modulator for some years and it has always had a high pitch noise that sounds abit like a mosquito . It is only noticeable on quiet sections of a film or on a menu screen. A friend of mine bought exactly the same one and his is fine , I bought another exactly the same and it is WORSE !..the noise is an octave lower and more noticeable . I know it is definately the modulator and not the TV . It does it on all my old sets. Does anyone have the same problems or a cure?
Alternatively, could anyone recommend a quiet , good quality modulator on the market?
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Old 16th Feb 2017, 10:18 am   #2
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Default Re: TV Modulator noise ....

Hi,
I will check the dragonsat modulator I have and see how noisy it is.
are you using the scart or phono inputs ?
Could it be noise from the internal power supply ?
regards Peter B
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Old 16th Feb 2017, 10:50 am   #3
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Default Re: TV Modulator noise ....

Hello Peter,
Yes, sorry my brain was not working last night. Long day broken down car etc... Yes it does sound like the power supply. I have not opened it up as of yet but I could almost guarantee it is a switch mode job. I suppose I could try changing the electrolytics on the power side. I am using a Scart lead from Freeview box to modulator, modulator RF out to TV. I have used the same freeview box with a video recorder as an RF modulator but the video recorder had to go as it was getting rather warm with a freeview box and a DVD player sat on top of it in a cabinet.
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Old 16th Feb 2017, 12:45 pm   #4
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Default Re: TV Modulator noise ....

I have a pair of Vision pro type modulators (DSB) for sale. Retail was 69 but will take 30 each if anyone is interested? They have phono connections for input and F type for loopthrough. Output level can be turned up quite high if required. Full band coverage 21-69. Audio modulation level is also adjustable.
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Old 17th Feb 2017, 12:17 am   #5
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Default Re: TV Modulator noise ....

Changed the caps in the power supply and made no difference ...still at square one (
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Old 17th Feb 2017, 12:28 am   #6
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Default Re: TV Modulator noise ....

Hi,
that was quick changing the caps ! Sorry it didn't make any difference. Has the modulator got a 2 core or three core mains lead ? Wondering if some extra grounding would help ? [ note it could make things worse ].
if you were to temporarily try using the phono connectors you could try disconnecting the audio inputs and see if it is the modulator itself that is making the noise, or could it be a combination of the units you are using ?
Hopefully someone with more relevant experience will be able to suggest some better suggestions .
regards Peter B
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Old 17th Feb 2017, 10:29 am   #7
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Default Re: TV Modulator noise ....

Hi Peter,
It is well grounded. I have tried it on different TVs and setups, If I use a VHS video recorder there is no problem... quiet as a mouse. If I remove the VHS and replace it with the Modulator I get the noise. I would definitely say it was the mod at fault.
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Old 17th Feb 2017, 5:29 pm   #8
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Default Re: TV Modulator noise ....

I've tried various modulators but now use a Maximum MT 57, the best yet. There is also the MT47 without stereo which you probably don't need.

Available here:

http://www.stuff-uk.net/search.aspx?q=TXQ0Nw==

Technical details here:

http://www.terraelectronics.com/Pub/...T57_manual.pdf
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Old 17th Feb 2017, 6:40 pm   #9
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Default Re: TV Modulator noise ....

I had one of those Maplin modulators a few years ago and the problem was exactly the same- a constant background noise on the audio. 'Mosquito' sums it up perfectly. Very irritating once you notice it. I couldn't live with it and ended up just using a VCR as a modulator.

Steve
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Old 18th Feb 2017, 12:05 am   #10
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Default Re: TV Modulator noise ....

Hi Steve ,
So, I take it it is a design fault ? It seems the more I read about it the more common the problem seem to be with these units. It would be nice to find and address the fault if it is at all possible.
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Old 18th Feb 2017, 12:14 am   #11
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Default Re: TV Modulator noise ....

Quote:
Originally Posted by winston_1 View Post
I've tried various modulators but now use a Maximum MT 57, the best yet. There is also the MT47 without stereo which you probably don't need.
Looks lab like ! , From what I can see It uses some screw type RF (satellite plugs?) and only supports RCA not scart. Do these run dead quiet? and is the picture quality good?
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Old 18th Feb 2017, 11:23 pm   #12
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Default Re: TV Modulator noise ....

I used to have one of these and I seem to remember reading that it was the side-effect of a in-built feature that somehow "enhanced" the audio in loud scenes (why?) but created this quiet whistling sound in quiet scenes.

I now use a Mercury RF modulator that is streets ahead and even has a SCART output as well.
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Old 18th Feb 2017, 11:41 pm   #13
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Default Re: TV Modulator noise ....

Ah!, @AidanLunn is it by any chance one of these doohickies?
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Old 19th Feb 2017, 6:14 am   #14
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Default Re: TV Modulator noise ....

Quote:
Originally Posted by AidanLunn View Post
I used to have one of these and I seem to remember reading that it was the side-effect of a in-built feature that somehow "enhanced" the audio in loud scenes (why?) but created this quiet whistling sound in quiet scenes.
That sounds like a dynamic range compressor. Reducing the volume during loud passages to prevent driving weedy TV speakers into distortion, but increasing it during quiet passages and amplifying the inevitable noise pickup. And curious how it's always done in the name of "improvement". I suspect that if they went the other way, with an expander that turned loud passages up and quiet ones down, then they could claim that as an improvement over the original sound as well!

Broadcasters do actually do something kind of similar themselves, but rather more sophisticated, and without so much of the extraneous noise.
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Old 19th Feb 2017, 4:32 pm   #15
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Default Re: TV Modulator noise ....

Quote:
Originally Posted by Valve'n'vinyl View Post
Ah!, @AidanLunn is it by any chance one of these doohickies?
That's the chappie!
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Old 19th Feb 2017, 11:27 pm   #16
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Default Re: TV Modulator noise ....

Quote:
Originally Posted by Valve'n'vinyl View Post
Looks lab like ! , From what I can see It uses some screw type RF (satellite plugs?) and only supports RCA not scart. Do these run dead quiet? and is the picture quality good?
Yes it uses F type connectors for the RF.
Yes it uses RCA for audio and video not scart. You don't need scart, no modulator uses RGB inputs.
Yes it is quiet and yes the picture quality is good.
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Old 20th Feb 2017, 10:17 am   #17
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Default Re: TV Modulator noise ....

Quote:
Originally Posted by AidanLunn View Post
That's the chappie!
Great! Thanks for the info, I will get one of the Mercury Rf Mods and try it out
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Old 25th Feb 2017, 1:19 am   #18
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Default Re: TV Modulator noise ....

@AidanLunn . Ok, I bought one of these little beauties and BOY ! What a difference . For starters , The background is quiet , no 'Mosquito' sound and secondly the picture is pin sharp . I am using this on a 26" ITT CVC5 and I can't believe I have spent the last 5 years watching it with a rubbish wooley picture from the rubbish Maplin modulator box . I would recommend one of these Mercury RF Modulators . I cannot fault it ! Thanks for every ones help !
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