Loses sparkle and highs as it warms up
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Loses sparkle and highs as it warms up
Hey people, I got really good sounding Laney VH100R but it only sounds great for about 10 - 15 minutes after that sound losses the highs, it becomes dull. Change happens for all channels equally. Something in a power section? Any ideas?
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Re: Loses sparkle and highs as it warms up
I did notice that it sounds better when biased colder, it keeps more sparkle and highs but it needs to be really cold I mean on 25 or 30% But again as it warms up it goes worse..
Re: Loses sparkle and highs as it warms up
That'll be the output tubes. The bias changes as they heat up, especially under playing conditions.
What's more, tubes are like incandescent light bulbs, and output tubes more so than pre-amp tubes. They wear out over time, (especially output tubes) and they become dull sounding. When they get really bad, they start to make random crackle and hiss noises. With any tube amp, every so often you need to put in a fresh set of output tubes.
Try changing the output tubes and see if that improves the sound.
What's more, tubes are like incandescent light bulbs, and output tubes more so than pre-amp tubes. They wear out over time, (especially output tubes) and they become dull sounding. When they get really bad, they start to make random crackle and hiss noises. With any tube amp, every so often you need to put in a fresh set of output tubes.
Try changing the output tubes and see if that improves the sound.
He who dies with the most tubes... wins
Re: Loses sparkle and highs as it warms up
It also may be the speakers warming up and their resistance increasing (thereby affecting their interaction with the amp), or hearing level shift.
Try recording it with a close mic to a speaker on one channel, direct from the amp's speaker output on another, and a room mic on another.
The recording will allow you to identify whether the change is affecting the amp output, the speaker, the room acoustics, or that there's no change, which points to it being your hearing.
Try recording it with a close mic to a speaker on one channel, direct from the amp's speaker output on another, and a room mic on another.
The recording will allow you to identify whether the change is affecting the amp output, the speaker, the room acoustics, or that there's no change, which points to it being your hearing.
https://www.justgiving.com/page/5-in-5-for-charlie This is my step son and his family. He is running 5 marathons in 5 days to support the research into STXBP1, the genetic condition my grandson Charlie has. Please consider supporting him!
Re: Loses sparkle and highs as it warms up
Yeah I'm thinking in a similar direction, because it is hard to replicate the problem while playing on low bedroom levels, but it always happens at the rehearsal or at live playing while I am pushing output harder.. But isn't the first sign of older power tubes that it takes longer to worm up, like when you turn on the amp. it takes a while to get the sound out? These tubes are fast in that way, no long waiting, maybe 5-10 seconds on stand by and you can play right away..tubeswell wrote:That'll be the output tubes. The bias changes as they heat up, especially under playing conditions.
What's more, tubes are like incandescent light bulbs, and output tubes more so than pre-amp tubes. They wear out over time, (especially output tubes) and they become dull sounding. When they get really bad, they start to make random crackle and hiss noises. With any tube amp, every so often you need to put in a fresh set of output tubes.
Try changing the output tubes and see if that improves the sound.
Re: Loses sparkle and highs as it warms up
The difference in warm-up time between old and new tubes is not so great that you would notice it in that way. With any tube amp, you should always keep a back-up set of output tubes handy so that you can change them when you need to (that's my motto anyway, which is why I'm forever buying new tubes to feed my numerous amps :-0 )Emetal wrote:...But isn't the first sign of older power tubes that it takes longer to worm up, like when you turn on the amp. it takes a while to get the sound out? These tubes are fast in that way, no long waiting, maybe 5-10 seconds on stand by and you can play right away..
He who dies with the most tubes... wins
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Stevem
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M
Are you playing the amp loud enough to have hearing fatigue take place, it happens faster as you get older!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: M
Well, I have the reference next me, the other guitar player and his amp, he sounds the same while mine takes a dive, so it is not hearing fatigue.Stevem wrote:Are you playing the amp loud enough to have hearing fatigue take place, it happens faster as you get older!
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Stevem
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- Joined: Fri Jan 24, 2014 3:01 pm
- Location: 1/3rd the way out one of the arms of the Milkyway.
M
Check the amps heater voltage when first fired up and then when the issue takes place.
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: M
That's a good idea, just hard to do, because I can not recreate the problem at bedroom levels, volume pot has to be at least at 2,5 or more and for 100W Laney that's LOUD. I will find a way though, wait, at the rehearsal I could simply pull out let's say one of 12ax7's tubes and take a voltage measurement between the 4th pin and ground (or 5th pin and ground) those are heather (filament) pins right?Stevem wrote:Check the amps heater voltage when first fired up and then when the issue takes place.
Re: M
In a 12A_7 preamp tube that is wired for 6.3VAC heaters, you need to measure between Pins 4 and 9, or between pins 5 and 9 - to get the 6V reading (Pins 4 and 5 are tied together on the socket).Emetal wrote:That's a good idea, just hard to do, because I can not recreate the problem at bedroom levels, volume pot has to be at least at 2,5 or more and for 100W Laney that's LOUD. I will find a way though, wait, at the rehearsal I could simply pull out let's say one of 12ax7's tubes and take a voltage measurement between the 4th pin and ground (or 5th pin and ground) those are heather (filament) pins right?Stevem wrote:Check the amps heater voltage when first fired up and then when the issue takes place.
If its wired for 12VAC heaters, you measure between pins 4 and 5 (to get the 12V reading).
(I suggest you use probes that are small enough to jam into the socket pin clamps without having to hold each probe. And unplug the amp before you set the probes up.)
He who dies with the most tubes... wins
Re: M
Yeap that's how it is in my Laney, Pins 4 and 5 are tied together on the socket.. Ok will do this at the first rehearsal, about 6 VAC is what should it be then all the time hah? We will seeIn a 12A_7 preamp tube that is wired for 6.3VAC heaters, you need to measure between Pins 4 and 9, or between pins 5 and 9 - to get the 6V reading (Pins 4 and 5 are tied together on the socket).
Also I will take spare power tubes that are close bias to the ones I have inside right now, so I can do fast switch and see does that changes anything...-
Stevem
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- Joined: Fri Jan 24, 2014 3:01 pm
- Location: 1/3rd the way out one of the arms of the Milkyway.
J
I see the amp has a surge guard off of the power socket, that could be going bad also.
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: Loses sparkle and highs as it warms up
There is no Surge Protector in the amp I do not now why they have it in the Schematic. Heater voltage is 6 VAC when turned on...will check what happens after worm up..
Re: Loses sparkle and highs as it warms up
That seems strange.
Are your probe tips sharp? If not, use a file etc to sharpen them, as they must break through oxide / flux to make proper contact.
Note that heater voltage is not usually described / measured with respect to the normal circuit 0V / chassis.
Where are you putting your probes to make this measurement?
What reading do you get if the tubes are removed?
Are your probe tips sharp? If not, use a file etc to sharpen them, as they must break through oxide / flux to make proper contact.
Note that heater voltage is not usually described / measured with respect to the normal circuit 0V / chassis.
Where are you putting your probes to make this measurement?
What reading do you get if the tubes are removed?
https://www.justgiving.com/page/5-in-5-for-charlie This is my step son and his family. He is running 5 marathons in 5 days to support the research into STXBP1, the genetic condition my grandson Charlie has. Please consider supporting him!