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    PAS-3 uneven L-R volume at low levels

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    lobby

    Posts : 18
    Join date : 2011-02-15

    PAS-3 uneven L-R volume at low levels

    Post by lobby on Fri Nov 06, 2015 2:10 pm

    When I am listening to my unit at very low volume levels, the right channel is slightly louder than the left channel until I turn it up a little more where they even out. What would be the cause of this?

    PeterCapo

    Posts : 380
    Join date : 2008-12-05

    Re: PAS-3 uneven L-R volume at low levels

    Post by PeterCapo on Fri Nov 06, 2015 2:32 pm

    If you have the original volume pot, it is probably the culprit.

    lobby

    Posts : 18
    Join date : 2011-02-15

    Re: PAS-3 uneven L-R volume at low levels

    Post by lobby on Fri Nov 06, 2015 2:56 pm

    PeterCapo wrote:If you have the original volume pot, it is probably the culprit.

    What are my options for replacement.  Not looking to throw a ton of money around on a pot, just want even volume at low levels.

    Will something like this work fine?

    https://www.radioshack.com/products/radioshack-100k-dual-ganged-stereo-volume-control?variant=5717293381

    peterh

    Posts : 643
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: PAS-3 uneven L-R volume at low levels

    Post by peterh on Fri Nov 06, 2015 4:11 pm

    lobby wrote:
    PeterCapo wrote:If you have the original volume pot, it is probably the culprit.

    What are my options for replacement.  Not looking to throw a ton of money around on a pot, just want even volume at low levels.

    Will something like this work fine?

    https://www.radioshack.com/products/radioshack-100k-dual-ganged-stereo-volume-control?variant=5717293381
    No.

    See http://www.tubenirvana.net/pas3-spare-parts.html for suggestions of working ones.

    An alternative is to make a signal damper ( 470k in series and 270k to ground on each output to
    the poweramp.) That way your volume won't be close to it's ends where it is most inaccurate.

    lobby

    Posts : 18
    Join date : 2011-02-15

    Re: PAS-3 uneven L-R volume at low levels

    Post by lobby on Fri Nov 06, 2015 4:46 pm

    peterh wrote:
    lobby wrote:
    PeterCapo wrote:If you have the original volume pot, it is probably the culprit.

    What are my options for replacement.  Not looking to throw a ton of money around on a pot, just want even volume at low levels.

    Will something like this work fine?

    https://www.radioshack.com/products/radioshack-100k-dual-ganged-stereo-volume-control?variant=5717293381
    No.

    See http://www.tubenirvana.net/pas3-spare-parts.html  for suggestions of working ones.

    An alternative is to make a signal damper ( 470k in series and 270k to ground on each output to
    the poweramp.) That way your volume won't be close to it's ends where it is most inaccurate.

    He has 3 different pots all at about $30. Which one is ideal?

    PeterCapo

    Posts : 380
    Join date : 2008-12-05

    Re: PAS-3 uneven L-R volume at low levels

    Post by PeterCapo on Fri Nov 06, 2015 4:48 pm

    You could "try" the Radio Shack pot and see how it does.  I had one of those and did not think much of it.  But, you could get lucky and get one that tracks reasonably well.

    Not familiar with peterh's "signal damper."

    The tube Nirvana pots, if I correctly read the listing, do not have loudness taps (please correct me if I am wrong).  In the PAS in particular, if you don't have loudness taps the volume will increase very rapidly with much less clockwise rotation of the pot, making it difficult or outright impractical to listen at lower volume levels.

    If you change the value of the pot from the original 250K to 100K, it might affect the phono section a little, but I don’t think too much.  Am a little rusty on this point, but have a read here: http://www.audioregenesis.com/documents/PAS_Phono.pdf

    I got one of these and it does pretty well (note I disconnected the phono section in my PAS): http://www.ebay.com/itm/1-X-MADE-JAPAN-ALPS-RK27-SERIES-100K-STEREO-VOLUME-CONTROL-POT-LOUDNESS-/301456600201?hash=item463036ac89    If that link doesn’t work, let me know and we’ll try again.

    At low volume levels, it might be difficult for anything but an expensive stepped setup to keep the channels even.  Possibly might not do better in terms of low volume channel tracking with any of these, but it's definitely worth a try.

    Peter


    Last edited by PeterCapo on Sat Nov 07, 2015 4:04 pm; edited 1 time in total (Reason for editing : Correction.)

    peterh

    Posts : 643
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: PAS-3 uneven L-R volume at low levels

    Post by peterh on Sat Nov 07, 2015 3:55 am

    The "damper" could easily be implemeted inside the pas-3, solder the 470k in series with the
    cable to the output rca connector, and make the loading resistor from the rca connector to ground.
    That way your existing pot don't need replacing but will find a new "working area" .

    MontanaWay

    Posts : 767
    Join date : 2014-02-06
    Age : 58
    Location : Cameron, Montana

    Re: PAS-3 uneven L-R volume at low levels

    Post by MontanaWay on Sat Nov 07, 2015 11:58 am

    PeterCapo wrote:You could "try" the Radio Shack pot and see how it does.  I had one of those and did not think much of it.  But, you could get lucky and get one that tracks reasonably well.

    Not familiar with peterh's "signal damper," so cannot comment on it.

    The tube Nirvana pots, if I correctly read the listing, do not have loudness taps (please correct me if I am wrong).  In the PAS in particular, if you don't have loudness taps the volume will increase very rapidly with much less clockwise rotation of the pot, making it difficult or outright impractical to listen at lower volume levels.

    If you change the value of the pot from the original 250K to 100K, it might affect the phono section a little, but I don’t think too much.  Am a little rusty on this point, but have a read here: http://www.audioregenesis.com/documents/PAS_Phono.pdf

    I got one of these and it does pretty well (note I disconnected the phono section in my PAS): http://www.ebay.com/itm/1-X-MADE-JAPAN-ALPS-RK27-SERIES-100K-STEREO-VOLUME-CONTROL-POT-LOUDNESS-/301456600201?hash=item463036ac89    If that link doesn’t work, let me know and we’ll try again.

    At low volume levels, it might be difficult for anything but an expensive stepped setup to keep the channels even.  Possibly might not do better in terms of low volume channel tracking with any of these, but it's definitely worth a try.

    Peter

    in my experience, using a pot without the loudness connection makes no difference in the control over the volume. You will still get the same amount of volume control, ie, 'not shorter or longer'.
    Most PAS2/3 owners who upgrade do away with the loudness function as well as the mono/stereo switch. It is completely taken out of the circuit. If you wish to retain tone controls, then either upgrade with our tone control upgrade kit, which consists of four new pots and a new set of capacitors, or go with the TCLA upgrade kit, together with either the Z-Mod PC6 or Z-Mod PH10 phono preamp upgrades.
    If you do go down the TCLA road, you must also upgrade the power supply, our Regulated Power supply v18 or v19, as the older style power supply and the PA211 transformers will not be able to adequately supply the extra tubes filament requirements as well as the B+.

    PeterCapo

    Posts : 380
    Join date : 2008-12-05

    Re: PAS-3 uneven L-R volume at low levels

    Post by PeterCapo on Sat Nov 07, 2015 4:23 pm

    MontanaWay wrote:in my experience, using a pot without the loudness connection makes no difference in the control over the volume. You will still get the same amount of volume control, ie, 'not shorter or longer'.

    Do you mean with your line stage or with the original Dynaco PC5 line stage?  Some people have reported this problem when lacking volume control loudness taps while retaining the original Dynaco line stage.  Reports can be found over in Dynaco Doctor forum archives, for instance.  Have a read through these threads where Joe Curcio's responses are notable, and I am sure I have seen others like these over time:

    http://www.audioasylum.com/forums/dynaco/messages/12/3143.html
    http://audioasylum.com/forums/dynaco/messages/1/14142.html

    Especially this one:
    http://audioasylum.com/forums/dynaco/messages/1/14144.html

    Other folks didn't seem to mind it, but I wanted to bring this up because the O.P. was emphasizing listening at low volume levels and thought I understood him to have the original PC5 line stage circuit.

    MontanaWay

    Posts : 767
    Join date : 2014-02-06
    Age : 58
    Location : Cameron, Montana

    Re: PAS-3 uneven L-R volume at low levels

    Post by MontanaWay on Sat Nov 07, 2015 4:31 pm

    no, with our line stage. Have not had any negative feedback whenever someone went the non loudness volume control way, be it our line stage or perhaps original.

    tubes4hifi
    Admin

    Posts : 1261
    Join date : 2008-11-30

    Re: PAS-3 uneven L-R volume at low levels

    Post by tubes4hifi on Sat Nov 07, 2015 8:44 pm

    Lobby,
    that's what balance controls are for. Even most $30 volume controls I've tested have very inaccurate tracking, especially at less than 1/2 volume,
    it's common to see 7-10% imbalance. I've got 21 step volume attenuators that are within 1% tracking over the entire range, $30.

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