Changing the caps has certainly proved the old ones were failing. I'm sure it does sound better because as it was before those regulators couldn't operate correctly and they were passing noise and ripple along to the front end stages they supply.
In my experience "voltage doubler arrangements" (post 39) are rare
in audio and at the moment I am only aware of this brand, Primare,
and Thule (both are using "identical" schematics).
in audio and at the moment I am only aware of this brand, Primare,
and Thule (both are using "identical" schematics).
Quite a lot of 'lo/mid fi' all in one systems used doublers and other weird arrangements to derive some rails, often display/front panel related. The parts used were just not suitably rated for the 'ripple' current they had to pass.
@Mooly , I am encountering this exact issue. Also based on the U.K. I am not allowed to directly message you. If you have it on hand, please let me know the list of capacitors and other bits and bobs I will need to recap this model. Also was wondering if it would be worth doing the MKIII upgrade from the service manual.
Also how would I identify if it was the transformer, or the capacitors, that are the source of the hum? Have multimeters and soldering equipment.
Best to keep it all in the thread 🙂
The image in post #8 shows the caps that fixed the hum on this one. They are in the voltage doubler arrangement. To recap it fully would need you to replace all electrolytics on a like for like basis and unless you have a specific issue I would not recommend that.
Transformers physically buzz, the noise comes from the transformer itself and not from the speakers.
It sounds like both. There is an audible buzz in the amplifier, and that same buzz can also be vaguely heard through the speakers.
I am aware this model is dual toroid.
Any recommendations on where I can source toroidal transformers from? It is my understanding there is a place in Poland that sells toroidal transformers.
I am aware this model is dual toroid.
Any recommendations on where I can source toroidal transformers from? It is my understanding there is a place in Poland that sells toroidal transformers.
No idea on that. You would need to determine all the secondary voltages and what VA rating is appropriate. Unfortunately lots of toroid's can be a bit noisy.
I am suggesting switching in the like for like transformer spec wise, if the transformer is the issue.
The spec would be 30 - 0 - 30, 9.5 - 0-9.5, 16.5 - 0 - 16.5. 150VA.
On the other hand, the U.K. team have quoted £100-180 + VAT in service fees.
The spec would be 30 - 0 - 30, 9.5 - 0-9.5, 16.5 - 0 - 16.5. 150VA.
On the other hand, the U.K. team have quoted £100-180 + VAT in service fees.
The transformer will not alter any hum or buzz from the speaker, it will only affect physical noise from the transformer itself and tbh you have no actual guarantee that the new one would be any quieter.
To improve the transformer situation noise-wise you can try to add more soft rubber on both sides of the fixture
or mount them inside dedicated potting items. A "dc filter", described elsewhere in the forum, can also help.
or mount them inside dedicated potting items. A "dc filter", described elsewhere in the forum, can also help.
As in, the U.K. repair people for Primare have quoted to me the above fee.
When I opened the case, it did seem the laminated stuff on one of the transformers was a bit loose/worse for wear.
It also seems to be the one buzzing sound is coming from.
The mentioned seller mentioned the amp taking a hefty knock/drop once.
When I opened the case, it did seem the laminated stuff on one of the transformers was a bit loose/worse for wear.
It also seems to be the one buzzing sound is coming from.
The mentioned seller mentioned the amp taking a hefty knock/drop once.
I am not sure I understand you reply properly, but adding more rubber
or other suitable soft material to the transformer mounting is always a
good idea. Most of the time only one thin layer of rubber is used, this
can lead to other problems also, see here :
https://www.diyaudio.com/community/...-schematic-diagrams-help.284017/#post-5960791
Pictures of A20 inside clearly show a standard poor way of mounting the
heavy transformers.
or other suitable soft material to the transformer mounting is always a
good idea. Most of the time only one thin layer of rubber is used, this
can lead to other problems also, see here :
https://www.diyaudio.com/community/...-schematic-diagrams-help.284017/#post-5960791
Pictures of A20 inside clearly show a standard poor way of mounting the
heavy transformers.
Hi. Just to mention, a Tacima Mains Conditioner fixed the issue of the hum going through to my speakers. There is still a very quiet hum from the amp itself, if I move my ear up to it, but running things through the mains conditioner eliminates the hum coming through to the speakers. However, turning off the amp results in a loudish pop sound. I suspect a grounding issue somewhere and wanted to know the best way to address this once and for all.
