No more Procrastination! (An interesting small valve head story)

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https://www.thetubestore.com/6v6-tube-review

 

[converse320]

My 20T arrived from Kenny's.  Well packed, everything as it should be, and very fast delivery.  Can't fault them.   Some immediate comments, using it with a 4 Ohm Mesa 1516.  Its noisy, quite a lot of hum coming through the speakers, which actually gets rather annoying after a bit when you are playing quietly.  I'm not sure this is a fault, or my bad mains.  Secondly, the gain knob doesn't really seem to do very much other than make it louder - doesn't really significantly change the character of the sound..  I was looking for that overdriven clanky sound - maybe its in there but I can't find it.  Finally, it goes really loud.  

So, a bit conflicted really.  On paper it looks like everything I need, in the flesh its a bit uninspiring so far.  Maybe it doesn't like 4Ohm cabs.

As an update - I've left it on overnight and its got a lot better - punchier and sounds much more interesting.  Still hums though.  I'll try some different mains cables, and maybe ask Kenny's if they'll swap the valves out if it doesn't resolve it.

Edited September 13, 2018 by converse320
update

[afterimage]

gone for the 50 a bit more versatile I think are used using a good hi fi mains cable 

[Quilly]

5 hours ago, Beer of the Bass said:

Tapping the valves through the cage using a cocktail stick revealed that it's the phase inverter 12au7/ecc82 that's microphonic.  I popped in a very old Telefunken ECC82 I had in my parts box, and it's much less microphonic, but still very slightly so.  So I reckon that with a fresh new valve I should be good to go.  It's a pain in the bum, but then so is going through another returns process...

 

That’s not ideal at all, I was literally moments away from pulling the trigger on this amp a couple of weeks ago, instead I bought a small mark bass practice amp (801).  I think I’ll hold on a while.

[Beer of the Bass]

I've just played through it for a while, with the old Telefunken in the phase inverter spot.  I must say, for all of the niggles (which I seem to have just got unlucky with), it is a very nice sounding amp.  It does this great articulate but grunty sound that I reckon will be fun to explore in a band context. 

[afterimage]

Mine has arrived this Morning the pf50 decided to push the boat on this one well worth p bass sounds great 

A bit of hum dimming through the speakers but sorted that some what with hi to mains cable 

Fender deluxe jazz active and passive sound excellent and p bass too 

I see why this can be used slot for recording 

Have left it on for an hour then standby for an hour  excellent service from Kenny's

[afterimage]

Just trying a Fender hot rod p j bass wow what a nice thump with both pickups on  split coil and vintage jazz

Gain about  ten o'Clock volume 12  tone about mid 

Ultra low is good too 

[afterimage]

Love the build quality and the controls nice notched feel to them 

Lots of Each options  ultra hi and low are very good options too

[markorbit]

On 12/09/2018 at 22:16, converse320 said:

My 20T arrived from Kenny's.  Well packed, everything as it should be, and very fast delivery.  Can't fault them.   Some immediate comments, using it with a 4 Ohm Mesa 1516.  Its noisy, quite a lot of hum coming through the speakers, which actually gets rather annoying after a bit when you are playing quietly.  I'm not sure this is a fault, or my bad mains.  As an update - I've left it on overnight and its got a lot better - punchier and sounds much more interesting.  Still hums though.  I'll try some different mains cables, and maybe ask Kenny's if they'll swap the valves out if it doesn't resolve it.

I think the hum is how they come. My PF20T is the same. There's a thread on Talkbass with instructions on how to reduce it further... it involves adding a capacitor or something. It's not a tube issue. In my experience it's common with all the PF tube amps. You'd think Ampeg of all manufacturers would get this right. I knew this when I bought it but at £299 I can live with it.

Edited September 15, 2018 by markorbit

[Bridgehouse]

The hum adds some authenticity to that 60s tube sound for me.. course, it’s not to everyone’s taste

[MoonBassAlpha]

The little Ashdown ctm15 does this too, it's quite noticeable when playing quietly. I attach my d.I. box to the speaker output, and you don't really hear the hum through the balanced output to the recording interface. The speaker attaches to the d.i. parallel output, but at only 15 watts it would be easy enough to hook up a power resistor as a dummy load for recording.

[Bridgehouse]

1 hour ago, MoonBassAlpha said:

The little Ashdown ctm15 does this too, it's quite noticeable when playing quietly. I attach my d.I. box to the speaker output, and you don't really hear the hum through the balanced output to the recording interface. The speaker attaches to the d.i. parallel output, but at only 15 watts it would be easy enough to hook up a power resistor as a dummy load for recording.

Funny, I just got a ctm15 from @Bigwan and it’s pretty much silent compared to the pf20!!

[markorbit]

2 minutes ago, Bridgehouse said:

Funny, I just got a ctm15 from @Bigwan and it’s pretty much silent compared to the pf20!!

My CTM15 was also silent... it was the same one 🙂

Edited September 15, 2018 by markorbit

[Bridgehouse]

Just now, markorbit said:

Mt CTM15 was also silent... it was the same one 🙂

Hahahar! It’s very different to the pf20 - like it a lot

[afterimage]

There a few things on the hum. Here goes

http://mnats.net/ampeg_pf-50t_hum_buster.html

[Beer of the Bass]

I'm just back from an afternoon gig in a park with my Pf-50t.  Can report that with my homebuilt 1x12" cabs, it has plenty of oomph for the band I'm playing with.  Sounded good too! We didn't run any bass through the PA, but the drums were also unmiked so that set the overall level. 

Regarding the Pf-50t and hum, I've had a peek inside mine, and can confirm that on mine at least, the hum fix linked above is now being applied to them.  Mine really isn't noisy, now that my valve issues are sorted.  So I feel like it was a good buy despite my initial niggles. 

Edited September 15, 2018 by Beer of the Bass

[krispn]

Solid tubeness brah

[afterimage]

Mine is delightful love the tone at the price it's well worth it  plenty of excellent tonal options with the pf50t

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https://www.dropbox.com/s/rc64ei1yypbr9e7/Ampeg PF50T Files.zip?dl=0&file_subpath=%2FAmpeg+PF50T+Files

[pbasspecial]

No hum on mine. Sounds pretty loud too. 

Usually with my hybrid amps I have my bass volume on full, preamp up high for grit and the master low for overall volume. 

However, I've been told by my guitarist that on valve amps it's good to roll the volume on the bass down, preamp quite low and to have the master volume close to full on. Adjust preamp, next and then use the bass volume lastly on stage for extra bite. Will give it a try. 

[Jus Lukin]

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Edited February 27, 2022 by Jus Lukin

[afterimage]

I like a bit  good Gain on as I can roll the volume off the bass with valve amps 

It's down to preference but definitely worth trying different parameters  have trilogic pre amp pedal to try out to with as well 

[Jus Lukin]

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Edited February 27, 2022 by Jus Lukin

[JapanAxe]

I've just read this thread and had my PF-50T GAS re-awakened, until I came across the hum thing. From reading this link posted by @afterimage,  it seems they sent a lot of units out with a noisy grid bias circuit. I am happy modding stuff, but not if I've bought it brand new. This demonstrates the difference it made:

 

[Beer of the Bass]

I was surprised at how quiet mine was after reading about the hum issues.  I had a look inside mine, and the mod was already carried out from new. Here's a pic of the relevant area on mine showing the added capacitor and resistor.  (the extra capacitor is the one on its side connected to the diode leg, and the added resistor is in series with R128).