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Ampeg PF-50T Humbuster
- Thread starter mnats
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- ampeg ampeg pf-50t pf-50t
WHAT??? You guys gettin' soft over there?
J/K...I know there's a markup over there due to shipping costs and stuff.
So the PF 20 has a noisy hum too? I have the PF 50, had the mod done, and it’s dead quiet, love it. Just got the PF 20, and it sounds like the blimp flying overhead- hummmmmmmmmmmmmmmm, lol. I’ll have to get the mod on that or send it back. I’ll call my local Ampeg service dealer this afternoon
I would reseat the tubes first. Then try swapping the small tubes with a good one out one at a time. You wouldn't think that Yamaha would let any products slip out the door that require the mod to work properly. A product sitting for a long time in a music store or a used amp is a different story.
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If the current in the output tubes is not balanced across the output transformer, the amp will hum.
Since the Ampeg service center is practically next door to my work, I just immediately took it. Now reading your replies I realize I should have at least tried to reseat the tubes- I think I had confirmation bias, as soon as the hum was present whether volume was up OR all the way down, I jumped to my default fear- that it needed a hum buster mod. I need to remember that tube amps are more roll up your sleeves and trouble shoot the gremlins than I am used to, having years of class D amp use did not prepare me for that process! One thing is for certain, it was way too loud of a hum for use in recording or bedroom practicing- my main purpose in buying the amp in the first place. Thanks for weighing in folks!
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Does this mod mean that 50T is potentially a 20db better signal to noise ratio amp than 20T since the specs state the same 60db signal to noise ratio for both of the amps?
Asking because I was about to order the 20T and this improvement is a big deal if that's the case.
Or, is 20T actually an already 80db signal to noise ratio amp but Ampeg stated the value conservatively as 60db because they didn't want 50T to look bad next to its sibling?
Has anybody compared them in person in terms of the noise/hum subject to this mod?
Best.
Asking because I was about to order the 20T and this improvement is a big deal if that's the case.
Or, is 20T actually an already 80db signal to noise ratio amp but Ampeg stated the value conservatively as 60db because they didn't want 50T to look bad next to its sibling?
Has anybody compared them in person in terms of the noise/hum subject to this mod?Best.
I've not sat down with a db meter in an anechoic chamberDoes this mod mean that 50T is potentially a 20db better signal to noise ratio amp than 20T since the specs state the same 60db signal to noise ratio for both of the amps?
Asking because I was about to order the 20T and this improvement is a big deal if that's the case.
Or, is 20T actually an already 80db signal to noise ratio amp but Ampeg stated the value conservatively as 60db because they didn't want 50T to look bad next to its sibling?
Best.
plus I don't have a 20T, but the first question is the most likely scenario.
I've not sat down with a db meter in an anechoic chamber
I’ve recorded in an anechoic chamber. Once you shut the door, the isolation is the weirdest audio sensation you can imagine.
Does this mod mean that 50T is potentially a 20db better signal to noise ratio amp than 20T since the specs state the same 60db signal to noise ratio for both of the amps?
Asking because I was about to order the 20T and this improvement is a big deal if that's the case.
Or, is 20T actually an already 80db signal to noise ratio amp but Ampeg stated the value conservatively as 60db because they didn't want 50T to look bad next to its sibling?
Best.
I don’t know what the signal to noise differences would be between the two amps. But I never believe published specs. They are all open to interpretation and their testing procedures.
The two amps are different designs, different tubes, transformers, and components. There a lot of potential variation in there. How well the power tubes are matched is also a consideration. I wouldn’t expect the noise specs to be the same.
I owned the PF20T & 50T for a month.
I kept the 50, I can't comment on the noise as both were fine but I know that the 50T was modded by the UK distributor before it was shipped.
What I can say is that IMO the 50 is a vastly superior amp to the 20.
I suspect that the 20 was more voiced to be closer the B15 where as the 50 is very much voiced like the bigger amps.
I had possession of a V4B recently for a month and the 50 sounds virtually identical.
If you can afford the 50 then go for that over the 20.
I kept the 50, I can't comment on the noise as both were fine but I know that the 50T was modded by the UK distributor before it was shipped.
What I can say is that IMO the 50 is a vastly superior amp to the 20.
I suspect that the 20 was more voiced to be closer the B15 where as the 50 is very much voiced like the bigger amps.
I had possession of a V4B recently for a month and the 50 sounds virtually identical.
If you can afford the 50 then go for that over the 20.
Very helpful thread. Thanks to @mnats, @Bertr and everyone else who has chimed in! I received a brand new humming PF-50T last week. I contacted the reseller who just confirmed that the local Ampeg service is aware of the problem and they will fix it at no charge. This means it will still be covered by full warranty. Good news!
You will love the mod- mine is now the quietest amp I own, you hear zero hum from mine.
My brand new 20t needed biasing only, I feel foolish for not checking that. It has a basically no appreciable hum at all, very quiet!
I've been lucky I guess . My PF-50 T is two years old and has been silent the whole time .
