Page 6 of 6 FirstFirst 123456
Results 176 to 203 of 203

Thread: 5F6A low volume

  1. #176
    Don't forget the joker g1's Avatar
    Join Date
    Feb 2010
    Location
    Canada, somewhere north of Fargo
    Posts
    11,759
    Thumbs Up/Down
    Received: 1,615/23
    Given: 4,135/11
    Rep Power
    22
    Why are you worried about 5.7VAC at the heaters? Is it causing a problem?
    It should run fine like that. If anything, it's better than running heaters 10% over, which many amps do.

    4 Not allowed! Not allowed!
    Just because they don't have tubes doesn't mean they don't have feelings! - glebert

  2. #177
    Member
    Join Date
    Dec 2013
    Location
    Sicily-Italy
    Posts
    105
    Thumbs Up/Down
    Received: 7/0
    Given: 10/0
    Rep Power
    6
    This is a small video that you hear background noise. Can you help me to find problem?
    https://youtu.be/vx6LWXCLwwQ

    0 Not allowed! Not allowed!

  3. #178
    Bent Member Chuck H's Avatar
    Join Date
    May 2007
    Location
    pacific north west
    Posts
    15,349
    Thumbs Up/Down
    Received: 2,323/4
    Given: 2,705/0
    Rep Power
    30
    That sounds like instability and/or possibly a bad tube or tubes to me.

    Do any of the controls affect the noise? If you turn down the treble does it stop?

    If you turn up the volume and treble does it get worse?

    If you tap on the tubes, what noises do they make?

    0 Not allowed! Not allowed!
    "Never bet your life on somebody else doing their job." SoulFetish's good friend

    "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

    "Being born on third base and thinking that you must have hit a triple is pure delusion!" Steve A

    "Back to the amp. It makes horrible sounds when I play my guitar thru it... because I suck at playing guitar." Mike6158

  4. #179
    Member
    Join Date
    Dec 2013
    Location
    Sicily-Italy
    Posts
    105
    Thumbs Up/Down
    Received: 7/0
    Given: 10/0
    Rep Power
    6
    I refer to background hum like not to whistles, even if this is a problem. Anyway, the whistles disappears after few minuts

    Hum is not affected by controls.

    Only V2 tube is noise on speaker when I tap it. But I changed three tubes in V2 and it is always noise at tap.

    0 Not allowed! Not allowed!

  5. #180
    Member
    Join Date
    Dec 2013
    Location
    Sicily-Italy
    Posts
    105
    Thumbs Up/Down
    Received: 7/0
    Given: 10/0
    Rep Power
    6
    Quote Originally Posted by Chuck H View Post
    That sounds like instability and/or possibly a bad tube or tubes to me.

    Do any of the controls affect the noise? If you turn down the treble does it stop?

    If you turn up the volume and treble does it get worse?

    If you tap on the tubes, what noises do they make?
    I'm amazed! I discoverd that V3 tube was too hot, then I swap it with new tube. Background hum and whistles are disappeared but amp volume is slightly decreased.

    Let's say that the volume that was first heard at 1 now we hear at 3

    0 Not allowed! Not allowed!

  6. #181
    Bent Member Chuck H's Avatar
    Join Date
    May 2007
    Location
    pacific north west
    Posts
    15,349
    Thumbs Up/Down
    Received: 2,323/4
    Given: 2,705/0
    Rep Power
    30
    Have you taken Helmholtz advice in posts 144 and 154 where he mentions cleaning and possibly tightening the tube sockets? If not then it's the very next thing you should do.

    0 Not allowed! Not allowed!
    "Never bet your life on somebody else doing their job." SoulFetish's good friend

    "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

    "Being born on third base and thinking that you must have hit a triple is pure delusion!" Steve A

    "Back to the amp. It makes horrible sounds when I play my guitar thru it... because I suck at playing guitar." Mike6158

  7. #182
    Supporting Member
    Join Date
    Mar 2018
    Location
    Germany
    Posts
    2,270
    Thumbs Up/Down
    Received: 1,729/1
    Given: 981/2
    Rep Power
    5
    I thought the V3 socket was replaced (#170)? Can you post a picture?

    0 Not allowed! Not allowed!
    - Own Opinions Only -

  8. #183
    Member
    Join Date
    Dec 2013
    Location
    Sicily-Italy
    Posts
    105
    Thumbs Up/Down
    Received: 7/0
    Given: 10/0
    Rep Power
    6
    Yes, I replaced all three preamp socket.

    This morning I turn on amp and I can confirm that volume is low compared to before.

    I measured voltage at pin 5 of power tubes and it is -44VDC. Is this too cold bias? Voltage across 1ohm resistors at pin 8 of power tubes is 22mV

    Also, I measured heater voltage and it is very very low, only 5VAC. I measured voltage at wall and it is 210VAC, then 12.5% less than nominal primary winding of my Hammond PT, that should give 6,7VAC heater voltage unload.

    Could one of these be the cause of low volume?

    Anyway, the heater voltage is a problem in my opinion.

    What to do?
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	20190110_115602.jpg 
Views:	22 
Size:	624.2 KB 
ID:	51872   Click image for larger version. 

Name:	20190110_113714.jpg 
Views:	20 
Size:	758.8 KB 
ID:	51873  

    0 Not allowed! Not allowed!

  9. #184
    Don't forget the joker g1's Avatar
    Join Date
    Feb 2010
    Location
    Canada, somewhere north of Fargo
    Posts
    11,759
    Thumbs Up/Down
    Received: 1,615/23
    Given: 4,135/11
    Rep Power
    22
    Can you put that other tube you had for V3 back in? Does the volume come back up?
    Your line voltage regulation from the power company is horrible. You need to check it every time you are doing any work on the amp.
    If your AC line is dropping as low as 210VAC, then you may have to do something about the heater voltage.
    When I said 5.7V heaters was ok, I was thinking that it would not go lower.

    0 Not allowed! Not allowed!
    Just because they don't have tubes doesn't mean they don't have feelings! - glebert

  10. #185
    Bent Member Chuck H's Avatar
    Join Date
    May 2007
    Location
    pacific north west
    Posts
    15,349
    Thumbs Up/Down
    Received: 2,323/4
    Given: 2,705/0
    Rep Power
    30
    I'm starting the think the inverse bucking transformer idea is a good one. The only rub would be that the amp may experience voltages that are too high whenever it's plugged in elsewhere.

    1 Not allowed! Not allowed!
    "Never bet your life on somebody else doing their job." SoulFetish's good friend

    "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

    "Being born on third base and thinking that you must have hit a triple is pure delusion!" Steve A

    "Back to the amp. It makes horrible sounds when I play my guitar thru it... because I suck at playing guitar." Mike6158

  11. #186
    Bent Member Chuck H's Avatar
    Join Date
    May 2007
    Location
    pacific north west
    Posts
    15,349
    Thumbs Up/Down
    Received: 2,323/4
    Given: 2,705/0
    Rep Power
    30
    Hey, wait a minute... My math alarm went off at some point. If 220V into a 240V primary is giving 5.7V then 210V should still be about 5.5V. Not 5V. Something else is going on.

    0 Not allowed! Not allowed!
    "Never bet your life on somebody else doing their job." SoulFetish's good friend

    "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

    "Being born on third base and thinking that you must have hit a triple is pure delusion!" Steve A

    "Back to the amp. It makes horrible sounds when I play my guitar thru it... because I suck at playing guitar." Mike6158

  12. #187
    Bent Member Chuck H's Avatar
    Join Date
    May 2007
    Location
    pacific north west
    Posts
    15,349
    Thumbs Up/Down
    Received: 2,323/4
    Given: 2,705/0
    Rep Power
    30
    vinceg,

    Can we please see a photo of the how the transformers are mounted? Something looks odd in your interior gut shots and I need to see how the transformers are mounted to understand it.

    0 Not allowed! Not allowed!
    "Never bet your life on somebody else doing their job." SoulFetish's good friend

    "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

    "Being born on third base and thinking that you must have hit a triple is pure delusion!" Steve A

    "Back to the amp. It makes horrible sounds when I play my guitar thru it... because I suck at playing guitar." Mike6158

  13. #188
    Member
    Join Date
    Dec 2013
    Location
    Sicily-Italy
    Posts
    105
    Thumbs Up/Down
    Received: 7/0
    Given: 10/0
    Rep Power
    6
    Quote Originally Posted by g1 View Post
    Can you put that other tube you had for V3 back in? Does the volume come back up?
    Your line voltage regulation from the power company is horrible. You need to check it every time you are doing any work on the amp.
    If your AC line is dropping as low as 210VAC, then you may have to do something about the heater voltage.
    When I said 5.7V heaters was ok, I was thinking that it would not go lower.
    No, other tube is bad, it broke and has air in. I can try another new tube.


    Quote Originally Posted by Chuck H View Post
    Hey, wait a minute... My math alarm went off at some point. If 220V into a 240V primary is giving 5.7V then 210V should still be about 5.5V. Not 5V. Something else is going on.
    The other day I had a 218V wall voltage and all out voltage of PT unload were about 8% less that nominal. Heater voltage were 6.2 unload. With tubes in it were about 5.7.
    yesterday, wall voltage were 210V, then about 12.5% less and heater voltage were 5V with tubes in. Is normal a drop voltage with tubes in, right?

    Quote Originally Posted by Chuck H View Post
    vinceg,

    Can we please see a photo of the how the transformers are mounted? Something looks odd in your interior gut shots and I need to see how the transformers are mounted to understand it.
    Ok, later I put pictures

    0 Not allowed! Not allowed!

  14. #189
    Member
    Join Date
    Dec 2013
    Location
    Sicily-Italy
    Posts
    105
    Thumbs Up/Down
    Received: 7/0
    Given: 10/0
    Rep Power
    6
    Now, wall voltage is 220V, heater voltage at PT unload is 6.2V and load 5.6V

    I did some tests. I measured voltage at V3 pins and I discovered that there is a 28V at pin 8 cathode.

    I changed V3 tube and now there is a 50 Hz background hum non affected by controls but volume is increased and cathode voltage is 35V.

    Then, with one tube, hum but volume right, with other tube no hum but volume lower

    Wall voltage is decreased to 210 and heater voltage with amp turn on and tubes in is 5V
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	20190111_072848.jpg 
Views:	23 
Size:	1.84 MB 
ID:	51887  

    0 Not allowed! Not allowed!
    Last edited by vinceg; 01-11-2019 at 11:16 AM.

  15. #190
    Bent Member Chuck H's Avatar
    Join Date
    May 2007
    Location
    pacific north west
    Posts
    15,349
    Thumbs Up/Down
    Received: 2,323/4
    Given: 2,705/0
    Rep Power
    30
    I think that low volume tube must be bad (good call g1).

    In my experience Hammond transformer heater voltages are a little high rather than low. Did you measure unloaded voltage with all tubes out or just power tubes out? Your loaded voltage with wall at 220V should probably be about 6V or a little more. That power transformer has a 4A (amps) filament winding and your amp should be drawing 2.85A from it (with the pilot lamp). I'm not ready to chalk up your low filament voltage entirely to the low mains voltage yet. I think something else may be contributing to the problem.

    I wasn't clear about what I wanted in a photo I guess. I want to see how your transformers (both of them) are mounted on the under side of the chassis.

    0 Not allowed! Not allowed!
    Last edited by Chuck H; 01-11-2019 at 03:23 PM.
    "Never bet your life on somebody else doing their job." SoulFetish's good friend

    "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

    "Being born on third base and thinking that you must have hit a triple is pure delusion!" Steve A

    "Back to the amp. It makes horrible sounds when I play my guitar thru it... because I suck at playing guitar." Mike6158

  16. #191
    Member
    Join Date
    Dec 2013
    Location
    Sicily-Italy
    Posts
    105
    Thumbs Up/Down
    Received: 7/0
    Given: 10/0
    Rep Power
    6
    Quote Originally Posted by Chuck H View Post
    I think that low volume tube must be bad (good call g1).

    In my experience Hammond transformer heater voltages are a little high rather than low. Did you measure unloaded voltage with all tubes out or just power tubes out? Your loaded voltage with wall at 220V should probably be about 6V or a little more. That power transformer has a 4A (amps) filament winding and your amp should be drawing 2.85A from it (with the pilot lamp). I'm not ready to chalk up your low filament voltage entirely to the low mains voltage yet. I think something else may be contributing to the problem.

    I wasn't clear about what I wanted in a photo I guess. I want to see how your transformers (both of them) are mounted on the under side of the chassis.
    Yes, my PT has a 6.7V unloaded heater voltage with the correct 240V primary voltage.
    This morning I measured unloaded heater voltage directly at PT wire by open fuse holder and this was 6.2V
    This is a picture of trasformers
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	20131028_180644.jpg 
Views:	20 
Size:	1.94 MB 
ID:	51890  

    0 Not allowed! Not allowed!

  17. #192
    Member
    Join Date
    Dec 2013
    Location
    Sicily-Italy
    Posts
    105
    Thumbs Up/Down
    Received: 7/0
    Given: 10/0
    Rep Power
    6
    I want to give you an update. I tried to remove V1 and hum is still there, I remove V2 and hum is stille there slightly quieter, I remove V3 and hum is disappeared. Then I swap V2 and V3 without changes, so I tried other new tubes on V3 and hum is disappeared but volume is decreased about 50% less. Then, I tried all my 12ax7 in V3 and no changes. I decided to reading voltages:


    B+ 410VDC


    V1
    pin1 210-220
    pin3 1.8
    pin6 215-225
    pin8 1.8


    V2
    pin1 188-190
    pin3 1.1
    pin6 328
    pin8 188


    V3
    pin1 271
    pin3 18
    pin6 375
    pin8 18


    V4
    pin4 420
    pin5 408
    pin6 -45
    pin7 408


    V5
    pin4 408
    pin5 408
    pin6 -45
    pin7 405


    In the same moment:


    wall voltage 213VAC
    heaters unloaded 5.95
    heaters loaded 4.6


    I noticed that fuse holder that contain 4A fuse for heaters wires were hot, I do not know if it is normal
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	20190113_093450.jpg 
Views:	12 
Size:	579.8 KB 
ID:	51924   Click image for larger version. 

Name:	20190113_093438.jpg 
Views:	14 
Size:	207.3 KB 
ID:	51925  

    0 Not allowed! Not allowed!

  18. #193
    Bent Member Chuck H's Avatar
    Join Date
    May 2007
    Location
    pacific north west
    Posts
    15,349
    Thumbs Up/Down
    Received: 2,323/4
    Given: 2,705/0
    Rep Power
    30
    Would the V3 cathode voltage of 18V be taken with the tube that made the amp lower in volume?

    Fuse wires shouldn't be hot. There must be resistance very near the area getting hot. There should not be resistance in the wire or the fuses to make them hot.

    I don't see anything wrong with your transformer layout. I cant see all the transformer wires though. There are some "lead dress" (wire routing) issues in your build though. But we should fix the low voltage and hum problems first.

    Take the preamp tube that has been causing low volume whenever it's used and throw it away. It's not good and using it confuses the tests.

    0 Not allowed! Not allowed!
    "Never bet your life on somebody else doing their job." SoulFetish's good friend

    "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

    "Being born on third base and thinking that you must have hit a triple is pure delusion!" Steve A

    "Back to the amp. It makes horrible sounds when I play my guitar thru it... because I suck at playing guitar." Mike6158

  19. #194
    Member
    Join Date
    Dec 2013
    Location
    Sicily-Italy
    Posts
    105
    Thumbs Up/Down
    Received: 7/0
    Given: 10/0
    Rep Power
    6
    Yes, the V3 cathode voltage of 18V is with the tube that made the amp lower in volume and quiet but the same tube before works fine and amp had hum.
    I do not know how to do

    0 Not allowed! Not allowed!

  20. #195
    Bent Member Chuck H's Avatar
    Join Date
    May 2007
    Location
    pacific north west
    Posts
    15,349
    Thumbs Up/Down
    Received: 2,323/4
    Given: 2,705/0
    Rep Power
    30
    Quote Originally Posted by vinceg View Post
    Yes, the V3 cathode voltage of 18V is with the tube that made the amp lower in volume and quiet but the same tube before works fine and amp had hum.
    I do not know how to do
    That tube is not good. It only makes the hum less because it makes the gain less. Don't use that tube anymore.

    You should have about 5.6V (loaded) on your heaters at 213 wall volts. I think something might be wrong with your heater wiring or a tube filament. This could also be causing the hum.

    Try removing the pilot lamp and re test the loaded heater voltage.

    0 Not allowed! Not allowed!
    "Never bet your life on somebody else doing their job." SoulFetish's good friend

    "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

    "Being born on third base and thinking that you must have hit a triple is pure delusion!" Steve A

    "Back to the amp. It makes horrible sounds when I play my guitar thru it... because I suck at playing guitar." Mike6158

  21. #196
    Supporting Member
    Join Date
    Mar 2018
    Location
    Germany
    Posts
    2,270
    Thumbs Up/Down
    Received: 1,729/1
    Given: 981/2
    Rep Power
    5
    V3
    pin1 271
    pin3 18
    pin6 375
    pin8 18
    Seems we still have the same problem as discussed before the socket change. As already mentioned, the high plate voltage at pin 6 (as well as the low common cathode voltage) mean that one of the triodes is not conducting current. (Its a double-triode having 2 separate heaters. One is internally connected to pins 9 and 4 , the other to pins 9 and 5. By jumpering socket contacts 4 and 5 the heaters are wired in parallel.)
    If only one of the triodes is operative, this results in low output and hum.

    Can you check that both filament wires are glowing?

    I suspect a socket wiring error/problem, especially regarding heaters. Can you check heater voltages between pin 9 and pins 4/5.
    Please check socket jumper connections between pins 4 and 5 as well as between pin 3 and 8. Also any wires shorting?

    0 Not allowed! Not allowed!
    Last edited by Helmholtz; 01-13-2019 at 03:53 PM.
    - Own Opinions Only -

  22. #197
    Bent Member Chuck H's Avatar
    Join Date
    May 2007
    Location
    pacific north west
    Posts
    15,349
    Thumbs Up/Down
    Received: 2,323/4
    Given: 2,705/0
    Rep Power
    30
    Quote Originally Posted by Helmholtz View Post
    Seems we still have the same problem as discussed before the socket change. As already mentioned, the high plate voltage at pin 6 (as well as the low common cathode voltage) mean that one of the triodes is not conducting current.
    Can you check that both filament wires are glowing?

    I suspect a socket wiring error/problem, especially regarding heaters. Can you check heater voltage between pin 9 and pins 4/5.
    Please check socket connections between pins 4 and 5 as well as between pin 3 and 8. Also any wires shorting?
    vinceg's reports indicate that this voltage condition only happens with one of his preamp tubes and not others and that it was that tube that was in the amp when these last voltage readings were taken.

    0 Not allowed! Not allowed!
    "Never bet your life on somebody else doing their job." SoulFetish's good friend

    "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

    "Being born on third base and thinking that you must have hit a triple is pure delusion!" Steve A

    "Back to the amp. It makes horrible sounds when I play my guitar thru it... because I suck at playing guitar." Mike6158

  23. #198
    Master Destroyer nosaj's Avatar
    Join Date
    Sep 2011
    Location
    Pace, FL
    Posts
    3,214
    Thumbs Up/Down
    Received: 1,096/102
    Given: 146/35
    Rep Power
    12
    Quote Originally Posted by Chuck H View Post
    vinceg's reports indicate that this voltage condition only happens with one of his preamp tubes and not others and that it was that tube that was in the amp when these last voltage readings were taken.
    Dumb question. Is it always the same tube in that socket or does a differsnt tube give roughly same data?

    nosaj

    0 Not allowed! Not allowed!
    Binkie McFartnuggets‏:If we really wanted to know the meaning of life we would have fed Stephen Hawking shrooms a long time ago.

  24. #199
    Member
    Join Date
    Dec 2013
    Location
    Sicily-Italy
    Posts
    105
    Thumbs Up/Down
    Received: 7/0
    Given: 10/0
    Rep Power
    6
    Update

    Heater problem is resolved, the cause was fuse holders. I noticed that moving heater wires pilot lamp went out. Now I've wall voltage of 230V and heater voltage of 6.1V

    Also I change the tube and now amp has right volume. I'm surprise to note how tubes are bad

    Hum remain to be fixed.

    0 Not allowed! Not allowed!

  25. #200
    Member
    Join Date
    Dec 2013
    Location
    Sicily-Italy
    Posts
    105
    Thumbs Up/Down
    Received: 7/0
    Given: 10/0
    Rep Power
    6
    Quote Originally Posted by nosaj View Post
    Dumb question. Is it always the same tube in that socket or does a differsnt tube give roughly same data?

    nosaj
    Believe me, I got confused. I think that tubes fall down because low heater voltage

    0 Not allowed! Not allowed!

  26. #201
    Supporting Member
    Join Date
    Mar 2018
    Location
    Germany
    Posts
    2,270
    Thumbs Up/Down
    Received: 1,729/1
    Given: 981/2
    Rep Power
    5
    Quote Originally Posted by vinceg View Post
    Update

    Heater problem is resolved, the cause was fuse holders. I noticed that moving heater wires pilot lamp went out. Now I've wall voltage of 230V and heater voltage of 6.1V

    Also I change the tube and now amp has right volume. I'm surprise to note how tubes are bad

    Hum remain to be fixed.
    Please update V3 voltages.

    0 Not allowed! Not allowed!
    - Own Opinions Only -

  27. #202
    Member
    Join Date
    Dec 2013
    Location
    Sicily-Italy
    Posts
    105
    Thumbs Up/Down
    Received: 7/0
    Given: 10/0
    Rep Power
    6
    Quote Originally Posted by Helmholtz View Post
    Please update V3 voltages.
    Now it is correct

    V3
    pin1 255
    pin3 41
    pin6 252
    pin8 41

    1 Not allowed! Not allowed!

  28. #203
    Member
    Join Date
    Dec 2013
    Location
    Sicily-Italy
    Posts
    105
    Thumbs Up/Down
    Received: 7/0
    Given: 10/0
    Rep Power
    6
    Update

    It seems that the cause of the hum is heater wires. I got up heater wire from V2 with a chopstick and hum has significantly reduced but not completely gone.

    What can I do to get better? Are they too close to signal wires? Can Heater elevation resolve?
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	20190113_164939.jpg 
Views:	24 
Size:	396.5 KB 
ID:	51926  

    0 Not allowed! Not allowed!

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. 5F6A Volume Interaction?
    By robrob in forum Theory & Design
    Replies: 5
    Last Post: 04-09-2016, 11:57 PM
  2. 5F6A problem?
    By vinceg in forum Debugging Your Build
    Replies: 39
    Last Post: 01-21-2014, 04:34 PM
  3. 5F6A woes
    By asatbluesboy in forum Tweed Builders
    Replies: 12
    Last Post: 09-13-2012, 03:00 PM
  4. 5F6A ?
    By chuckb in forum Tweed Builders
    Replies: 17
    Last Post: 02-17-2010, 09:45 PM
  5. 5F6A popping
    By jpbondo in forum Maintenance, Troubleshooting & Repair
    Replies: 4
    Last Post: 01-08-2007, 08:02 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •