AP20 volume

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Quarknosis
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AP20 volume

Unread post by Quarknosis »

I've been using my AP20 in a second system but some changes mean that I am planning to use it for headphone listening only.

I was never able to get the volume control over 9 o'clock without complaints from the rest of the family that it was too loud and now when listening with headphones I'm not getting past 10 o'clock. This seems a waste of at least 2/3 of the volume control to me. Would it make any sense to have the amp modified so that I could use more of the volume control, my theory being that it would also give better fine adjustment and would potentially help with the channel imbalance that there is in the first few mm of movement.
Main System. Amp - Luxman LV-120, CD - Pioneer PDX505 & Hitachi DA 401. Turntable - Trio KD-2055/Denon DL-110 & Ortofon VMS20E. Cassette Deck - JVC KD A55. Speakers - Arcam Alpha connected with NVA LS3.

Headphone System - Little Dot Mkiii headphone amp, various vintage CD players into NVA P50 with Sennheiser HD600 and Beyer DT 880

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Re: AP20 volume

Unread post by karatestu »

Reducing the signal level from the source would involve the addition of some resistors (like an L pad). Some people claim attenuators ruin the sound whilst others say they can't hear them in circuit. I have never had the need to try them.

I don't know if a stepped attenuator will fit in the the AP20 ? That would help with low level channel balance.
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Quarknosis (Sun Jun 21, 2020 5:57 pm)
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Re: AP20 volume

Unread post by Quarknosis »

karatestu wrote: Sun Jun 21, 2020 5:33 pm Reducing the signal level from the source would involve the addition of some resistors (like an L pad). Some people claim attenuators ruin the sound whilst others say they can't hear them in circuit. I have never had the need to try them.

I don't know if a stepped attenuator will fit in the the AP20 ? That would help with low level channel balance.
Thanks for your comments Stu.

I've searched the archives and apparently there is a 470ohm resistor as standard but this can/was changed, anything from 330 to 680, depending on the headphones specified at the time of ordering so it can be done. I suspect the position of this particular resistor would only lower the headphone output and wouldn't help with the speakers. I'd make the change myself if I knew where the relevant part was and providing access to it is easy enough once the lid is off.

I know that the old stepped attenuator wouldn't fit into the AP20 and I suspect the new one won't either unless Paul and Tomasz know different? I do find that the old stepped attenuators helped to reduce the overall volume slightly as well solving the early channel imbalance.
Main System. Amp - Luxman LV-120, CD - Pioneer PDX505 & Hitachi DA 401. Turntable - Trio KD-2055/Denon DL-110 & Ortofon VMS20E. Cassette Deck - JVC KD A55. Speakers - Arcam Alpha connected with NVA LS3.

Headphone System - Little Dot Mkiii headphone amp, various vintage CD players into NVA P50 with Sennheiser HD600 and Beyer DT 880

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Re: AP20 volume

Unread post by karatestu »

You are welcome. I see you are talking about the resistor in series with the signal between the amp board output and the headphone socket. I was talking about something else so forget the Lpad bit.

Maybe the resistor can be increased to 680R without any detrimental effects with your headphones. Tomasz would be the one to know that seeing as he is very interested in headphones.

Edit to add - maybe an in line attenuator is the only way if you also want to change the volume pot sensitivity on speaker use as well. Doc would have probably said they are the devil's work however.
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Quarknosis (Sun Jun 21, 2020 7:57 pm)
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Re: AP20 volume

Unread post by Ithilstone »

Is your AP20 already fitted with HP socket? If yes the it is a case of finding right resistor to match with your headphones.

Stu - depending on age ( and internal layout ) some AP20 can be fitted with SA - it would involve swapping volume control with input selector tough so front markings would be useless - Doc was against it full stop - but if one was happy with markings being removed...
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karatestu (Sun Jun 21, 2020 7:49 pm) • Quarknosis (Sun Jun 21, 2020 7:57 pm)
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Re: AP20 volume

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Ithilstone wrote: Sun Jun 21, 2020 7:43 pm Is your AP20 already fitted with HP socket? If yes the it is a case of finding right resistor to match with your headphones.

Stu - depending on age ( and internal layout ) some AP20 can be fitted with SA - it would involve swapping volume control with input selector tough so front markings would be useless - Doc was against it full stop - but if one was happy with markings being removed...
Yes there is a headphone socket fitted already. So is it a case of impedence matching for the specific headphone or is there something that can be done to reduce the overall volume on both headphone and speaker output?

As far as markings on amps is concerned, I don't see why inputs and switches aren't marked 1, 2, 3 etc or something else that is not text, in this day and age when disc, tuner and video might not be among the source components.
Main System. Amp - Luxman LV-120, CD - Pioneer PDX505 & Hitachi DA 401. Turntable - Trio KD-2055/Denon DL-110 & Ortofon VMS20E. Cassette Deck - JVC KD A55. Speakers - Arcam Alpha connected with NVA LS3.

Headphone System - Little Dot Mkiii headphone amp, various vintage CD players into NVA P50 with Sennheiser HD600 and Beyer DT 880

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Re: AP20 volume

Unread post by Ithilstone »

Quarknosis wrote: Sun Jun 21, 2020 7:57 pm
Ithilstone wrote: Sun Jun 21, 2020 7:43 pm Is your AP20 already fitted with HP socket? If yes the it is a case of finding right resistor to match with your headphones.

Stu - depending on age ( and internal layout ) some AP20 can be fitted with SA - it would involve swapping volume control with input selector tough so front markings would be useless - Doc was against it full stop - but if one was happy with markings being removed...
Yes there is a headphone socket fitted already. So is it a case of impedence matching for the specific headphone or is there something that can be done to reduce the overall volume on both headphone and speaker output?

As far as markings on amps is concerned, I don't see why inputs and switches aren't marked 1, 2, 3 etc or something else that is not text, in this day and age when disc, tuner and video might not be among the source components.
It looks like, in your case, higher value high quality padding resistor is needed.
for overall volume something like stepped attenuator may be possible - any other solution will reduce sound quality.

when (or if) we reintroduce integrated we will be looking at new design and text markings are very unlikely
for existing integrated we could only offer to remove markings completely if swapping volume with input selector would be an option.
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Quarknosis (Sun Jun 21, 2020 9:49 pm)
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Re: AP20 volume

Unread post by Quarknosis »

I'll bear that in mind, might have to start saving for a potential upgrade :)
Main System. Amp - Luxman LV-120, CD - Pioneer PDX505 & Hitachi DA 401. Turntable - Trio KD-2055/Denon DL-110 & Ortofon VMS20E. Cassette Deck - JVC KD A55. Speakers - Arcam Alpha connected with NVA LS3.

Headphone System - Little Dot Mkiii headphone amp, various vintage CD players into NVA P50 with Sennheiser HD600 and Beyer DT 880

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