pop noise during warmup

[sparkie]

The GL KT77's were the only ones it happens with. And yet not all the time....Today in the morning did not hear any pop. Later in the day I did---
That being said I'm friends with the amps actual designer who said not to worry----its not a loud noise that can stretch a voice coil-------and a fair amount of people experienced this.....

Its because they designed that amp with a lot of capacitance in the supply.

 

[dtbradio]

the tube circuit doesn't have to be started for effects like exceeding cathode to heater voltage rating to happen.

Wasn't thinking of that, but makes total sense.

 

[DasguteOhr]

A defective spark quenching capacitor on the power switch can cause this noise. If not available, retrofit. Attention must have x2 specification. It mitigates temporary current impulses when you switching on.
There are a variety of causes for the problem, I would start with that.
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[sparkie]

A defective spark quenching capacitor on the power switch can cause this noise. If not available, retrofit. Attention must have x2 specification. It mitigates temporary current impulses when you switching on.
There are a variety of causes for the problem, I would start with that.
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We don't know what amp it is, and why would someone put something like that across a power switch on a tube amp?

 

[Another Johnson]

We don't know what amp it is, and why would someone put something like that across a power switch on a tube amp?

In post #10 the op says it’s a Prima Luna integrated. Upscale, the Prima Luna importer in the US, has already told him to not worry about it. The problem is random according to the OP. Just one of those quirks that comes along as one of the joys of tubes.

 

[sparkie]

In post #10 the op says it’s a Prima Luna integrated. Upscale, the Prima Luna importer in the US, has already told him to not worry about it. The problem is random according to the OP. Just one of those quirks that comes along as one of the joys of tubes.

Looking at it, yes, its a poorly designed power supply with too much capacitance. It probably run ok with EL34s. Look at that crap ribbon wire tough with molex connectors too.

 

[DasguteOhr]

We don't know what amp it is, and why would someone put something like that across a power switch on a tube amp?

because this belongs in every amp that is designed properly. Prevents contact erosion on the switch. and it prevents switching noises

 

[DasguteOhr]

Looking at it, yes, its a poorly designed power supply with too much capacitance. It probably run ok with EL34s. Look at that crap ribbon wire tough with molex connectors too.

Complete nonsense, Powersupply is CLC filter no noise or plop at start. that choke prevents excessive charging peaks. Tube sockets are not mounted on circuit board. good Takman resistors. Gas-tight relays in the input, short signal paths. OK, let's think about the cable routing and fastening. Overall, a long-term, reliable device. tube failure protection circut.
There are clearly expensive devices that are constructed worse.

 

[sparkie]

Complete nonsense, Powersupply is CLC filter no noise or plop at start. that choke prevents excessive charging peaks. Tube sockets are not mounted on circuit board. good Takman resistors. Gas-tight relays in the input, short signal paths. OK, let's think about the cable routing and fastening. Overall, a long-term, reliable device. tube failure protection circut.
There are clearly expensive devices that are constructed worse.

When there is only two board manufacturers in the world that can make appropriate PC boards for tubes properly, its best to look for point to point hand wired every time. I just don't like the wires they used. It reminds me of working on consumer audio gear in a shop long ago. Oh yea I've seen worse. I repaired someone's $200K SSL audio mixer because their studio techs didn't want to work on it because of the high voltage rails. I found it interesting that those guys in that sector are changing boards out not realizing the only thing wrong is the connector the manufacturer used.

At least the tube stage wiring meets my approval. A lot don't. Especially China-tech.

 

[Another Johnson]

Phantom capacitance and antenna effects change from sample to sample due to small differences in wire routing. A modern multilayer pc board is consistent from sample to sample. Warren Gehl has pointed out that going to the current multilayer board designs led to significant sonic improvements for ARCs current designs.

Of course a repair shop would hate the multilayer board for both troubleshooting and repairs.

I am not a Prima Luna fan (having owned one of their integrateds several years ago). It was noticeably not as enjoyable to listen to as integrateds from McIntosh, Levinson, or ARC that I owned at the same time. As for their advertising campaign that tells you they’re better than others because of their build quality…. I would ask “Do you want to look at it, or listen to it?”

 

[sparkie]

Phantom capacitance and antenna effects change from sample to sample due to small differences in wire routing. A modern multilayer pc board is consistent from sample to sample. Warren Gehl has pointed out that going to the current multilayer board designs led to significant sonic improvements for ARCs current designs.

Of course a repair shop would hate the multilayer board for both troubleshooting and repairs.

I am not a Prima Luna fan (having owned one of their integrateds several years ago). It was noticeably not as enjoyable to listen to as integrateds from McIntosh, Levinson, or ARC that I owned at the same time. As for their advertising campaign that tells you they’re better than others because of their build quality…. I would ask “Do you want to look at it, or listen to it?”

multi layer boards are usually not an issue for an expirience tech that would know where to go to next. Its just repairing the circuit when something self destructs them in between layers.

I like tube hybrid amps the other way: Tube preamp and solid state output. I think its the best of both worlds.

 

[Republicoftexas69]

multi layer boards are usually not an issue for an expirience tech that would know where to go to next. Its just repairing the circuit when something self destructs them in between layers.

I like tube hybrid amps the other way: Tube preamp and solid state output. I think its the best of both worlds.

Agree 1000%

 

[Another Johnson]

multi layer boards are usually not an issue for an expirience tech that would know where to go to next. Its just repairing the circuit when something self destructs them in between layers.

I like tube hybrid amps the other way: Tube preamp and solid state output. I think it’s the best of both worlds.

More than one US brand will no longer sell their boards (or other parts for that matter) to third party shops. Part of this is to protect IP from the current climate that encourages IP theft and counterfeiting, but part of it is to maintain factory control of QC.

FWIW, there aren’t a lot of “experienced techs” out there offering repair services on current high end audio products. McIntosh is the best at service center support. ARC has a few approved alternatives to a return trip to the factory. With Levinson, Krell, Burmester, Conrad Johnson and several others, a local privateer is unlikely to get factory part or schematic support.

Point to point allows the clever local guy to “repair, and even upgrade” a piece of broken gear without a schemstic or factory part support. What is going on is a lot clearer to the naked eye.

Guitar amp techs who are willing to troubleshoot far prefer point to point. Guitar amps don’t have to achieve perfect amplification. Distortion is sought after and characterizes the sound of the amp. Audiophile amps are trying to be perfect and consistent. Point to point makes it more difficult to achieve the desired consistency.

It’s not important. People like Prima Luna, going so far as to see them as an audio sandbox for tube rolling. Point to point works well in this marketing model.

 

[sparkie]

FWIW, there aren’t a lot of “experienced techs” out there offering repair services on current high end audio products. McIntosh is the best at service center support. ARC has a few approved alternatives to a return trip to the factory. With Levinson, Krell, Burmester, Conrad Johnson and several others, a local privateer is unlikely to get factory part or schematic support.

When I was in consumer electronics repair,it wasn't much an issue. I fixed most things without schematics, but those guy would provide me with data if I needed to because they treated ISCET people differently than your normal techs. Sometimes, I had to have a IP protection clause on file with them, but not many did that either.

 

[shel50]

Looking at it, yes, its a poorly designed power supply with too much capacitance. It probably run ok with EL34s. Look at that crap ribbon wire tough with molex connectors too.

Nothing from primaluna is poorly designed or built..nothing
Been using Primaluna over 20 years..I'll take over amps 10 x the cost