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Ampeg PF-50t

#81
With most bass amps (especially valve ones), I have to use a compressor. Probably due to my uneven, hard picking. But one have to realise that if one uses a JCM800 'all at noon' with a guitar, one is already in Paul Kossof territory!
These vintage bass amps HAD to be used at low settings not to distort (hence the old rule of thumb: 50w gtr amp, 200w bass amp).
That is precisely why Trace Eliott made a killing back in the 90's: They started from a PA amp, and only then they tweaked it for bass. They thought massive 'Hi-Fi', not guitar amp for bass (VOX, Fender style).
 
#82
OK, so here's what's going on...I also use basses with Geezers, BTW, and your amp is working as it should.

Yes, around 10:00 is the breakup point for the gain on the PF-50T with my Geezer-loaded basses. Doesn't mean you're getting cheated out of clean wattage or anything. It's by design. If you want it to be clean, crank the master and keep the gain below 10:00. But if you want it to be gnarly, you can keep it around 10:00 and get some cool light breakup, or you can crank it beyond 10:00 and add in some power tube distortion as well and get really gnarly.

Now the reason it doesn't sound as good to you as it could is because when you run it direct, you are getting full range sound, which means you're getting all the "tweeter frequencies" that make distortion sound bad. You need to cut your highs completely past 4 or 5 khz. There are a couple different ways you can do it, like micing a cab, loading up a graphic EQ plugin and pushing down all the sliders past 4 or 5 khz, adding a cab simulator pedal, but the way I do it is with a low pass filter pedal. I use one made by Broughton Audio from Canada (if you're interested, https://www.broughtonaudio.com/ ). The Broughton is very cool because it only cuts highs and doesn't change the sound otherwise. I find it indispensible because I like at least a little mild overdrive most of the time and I hate tweeter frequencies on electric, and it's very small and the price is decent.

But your amp is fine. Sounds really good too, except for those tweeter frequencies.
 
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#83
JimmyM said:
OK, so here's what's going on...I also use basses with Geezers, BTW, and your amp is working as it should.

Yes, around 10:00 is the breakup point for the gain on the PF-50T with my Geezer-loaded basses. Doesn't mean you're getting cheated out of clean wattage or anything. It's by design. If you want it to be clean, crank the master and keep the gain below 10:00. But if you want it to be gnarly, you can keep it around 10:00 and get some cool light breakup, or you can crank it beyond 10:00 and add in some power tube distortion as well and get really gnarly.

Now the reason it doesn't sound as good to you as it could is because when you run it direct, you are getting full range sound, which means you're getting all the "tweeter frequencies" that make distortion sound bad. You need to cut your highs completely past 4 or 5 khz. There are a couple different ways you can do it, like micing a cab, loading up a graphic EQ plugin and pushing down all the sliders past 4 or 5 khz, adding a cab simulator pedal, but the way I do it is with a low pass filter pedal. I use one made by Broughton Audio from Canada (if you're interested, https://www.broughtonaudio.com/ ). The Broughton is very cool because it only cuts highs and doesn't change the sound otherwise. I find it indispensible because I like at least a little mild overdrive most of the time and I hate tweeter frequencies on electric, and it's very small and the price is decent.

But your amp is fine. Sounds really good too, except for those tweeter frequencies.
Click to expand...

Thank you all! What would I do without TB.

What you say about gain staging is the way my amp is working. Reassuring when Jimmy says it`s ok.
I know the best result for recording direct is through speaker sim, eq and so on (often blended with dry signal). I`ve got the Broughton hp/lp but have not thought of using it on the line signal. Great advice!
I really look forward to rock this thing with a cab this weekend. What a perfect amp!
 
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#84
JimmyM said:
OK, so here's what's going on...I also use basses with Geezers, BTW, and your amp is working as it should.

Yes, around 10:00 is the breakup point for the gain on the PF-50T with my Geezer-loaded basses. Doesn't mean you're getting cheated out of clean wattage or anything. It's by design. If you want it to be clean, crank the master and keep the gain below 10:00. But if you want it to be gnarly, you can keep it around 10:00 and get some cool light breakup, or you can crank it beyond 10:00 and add in some power tube distortion as well and get really gnarly.

Now the reason it doesn't sound as good to you as it could is because when you run it direct, you are getting full range sound, which means you're getting all the "tweeter frequencies" that make distortion sound bad. You need to cut your highs completely past 4 or 5 khz. There are a couple different ways you can do it, like micing a cab, loading up a graphic EQ plugin and pushing down all the sliders past 4 or 5 khz, adding a cab simulator pedal, but the way I do it is with a low pass filter pedal. I use one made by Broughton Audio from Canada (if you're interested, https://www.broughtonaudio.com/ ). The Broughton is very cool because it only cuts highs and doesn't change the sound otherwise. I find it indispensible because I like at least a little mild overdrive most of the time and I hate tweeter frequencies on electric, and it's very small and the price is decent.

But your amp is fine. Sounds really good too, except for those tweeter frequencies.
Click to expand...
So, in a studio situation, are you saying keep the Gain at 8 o'clock and dime the master for a clean signal out of the Trans DI ?
 
#86
jnewmark said:
So, in a studio situation, are you saying keep the Gain at 8 o'clock and dime the master for a clean signal out of the Trans DI ?
Click to expand...

This is what I would recommend too. Not necessarily 8:00 but probably before 10:00 as it will start to break up(depending upon your input signal of course) around there. With a P-Bass and the amp set around 10:00 it will overdrive a little if I dig in. Another point.. these amps do have some operational hum(low) that you can hear when you flip standby. Its normal.
 
#87
jnewmark said:
So, in a studio situation, are you saying keep the Gain at 8 o'clock and dime the master for a clean signal out of the Trans DI ?
Click to expand...
You don't have to keep it that low. Like Briton and AMJ said, 9:30 is probably low enough for a bass with a typical Fender output. But depending on the overload point on the studio gear you're plugging into, yeah, somewhere around that point.
 
#88
niels1 said:
Thank you all! What would I do without TB.

What you say about gain staging is the way my amp is working. Reassuring when Jimmy says it`s ok.
I know the best result for recording direct is through speaker sim, eq and so on (often blended with dry signal). I`ve got the Broughton hp/lp but have not thought of using it on the line signal. Great advice!
I really look forward to rock this thing with a cab this weekend. What a perfect amp!
Click to expand...
How are you feeling about it now? I really want to believe!
 
#89
AMJBASS said:
This is what I would recommend too. Not necessarily 8:00 but probably before 10:00 as it will start to break up(depending upon your input signal of course) around there. With a P-Bass and the amp set around 10:00 it will overdrive a little if I dig in. Another point.. these amps do have some operational hum(low) that you can hear when you flip standby. Its normal.
Click to expand...
Operational hum ? If using the head with a cab, does it come through the speaker ? Reason I ask is that I typically use a DI and mic the cab in the studio. A hum coming through the cab would be a bad thing, I would imagine.
 
#90
noeinstein said:
How are you feeling about it now? I really want to believe!
Click to expand...
I like this amp a lot! In a mix/band the high frequency distortion isn´t noticeable but it is when playing alone. I still don`t like that. So to me the best results are when I`m running the amp relatively clean and just add a pedal in front if I want to push it. Then it`s great! In fact I sold my vintage V4B today because the PF-50T fits all my needs better. I`m still learning and tweaking. So much fun with this amp!
 
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#91
jnewmark said:
Operational hum ? If using the head with a cab, does it come through the speaker ? Reason I ask is that I typically use a DI and mic the cab in the studio. A hum coming through the cab would be a bad thing, I would imagine.
Click to expand...

Doesn't come through the speakers or either DI. Its just electrical hum. Not noticeable at all when playing.

For the last several weeks I have been using the PF50T with the master on full for every gig I have used it on(which is most of them!). I like it a lot this way. Clean, clear, but when you start pushing the amp into happy zone, if the gig gets that loud, it has this harmonically big and rich sound as the power tubes start to saturate. I almost never get this loud. 50 watts has been more than plenty for every gig I have been playing lately. Having a great sound slots much better in a mix rather than having a loud sound to compete with guitars/keys etc.
 
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#92
AMJBASS said:
Doesn't come through the speakers or either DI. Its just electrical hum. Not noticeable at all when playing.

For the last several weeks I have been using the PF50T with the master on full for every gig I have used it on(which is most of them!). I like it a lot this way. Clean, clear, but when you start pushing the amp into happy zone, if the gig gets that loud, it has this harmonically big and rich sound as the power tubes start to saturate. I almost never get this loud. 50 watts has been more than plenty for every gig I have been playing lately. Having a great sound slots much better in a mix rather than having a loud sound to compete with guitars/keys etc.
Click to expand...
Thanks. I'm mostly interested in this amp for studio work. Any kind of buzz or hum drives the studio guys nuts. There was an issue with noise and buzz with these heads, in fact, there is a thread here on TB dedicated to discussing it. I believe Jimmy M said Ampeg was aware of it and the newer heads had a fix for the issue. Obviously, you must have one of the newer ones.
 
#94
jnewmark said:
Thanks. I'm mostly interested in this amp for studio work. Any kind of buzz or hum drives the studio guys nuts. There was an issue with noise and buzz with these heads, in fact, there is a thread here on TB dedicated to discussing it. I believe Jimmy M said Ampeg was aware of it and the newer heads had a fix for the issue. Obviously, you must have one of the newer ones.
Click to expand...

The issue with the hum was related to the power tube bias circuit. The solution was to a an additional capacitor to smooth the ripple. Picture a DC voltage with some wobble at the top, not rock solid smooth like a battery, for example, would produce.

The newer Portaflex amps have a good feature to help keep the amp quieter. The preamp heater voltage, which could be AC, is rectified to convert to DC and have a capacitor to filter the ripple. It’s the ripple that causes the hum. This is fairly standard in modern amps. DC heaters in the preamp help keep things quieter because the signal level is not that much above the noise floor. So everything gets amplified. The DC heater helps separate the signal from the noise by lowering the noise floor.

How can the amp’s noise be improved? The power tube heaters are AC. Hum is generally not such an issue, but it can be, in a power amp because the signal levels are higher than in a preamp relative to the noise floor. So a low level heater hum is swamped out relative to the signal level.

In a studio amp, DC heaters to all tubes could make it quieter. An even better way to produce a DC heater voltage is to use voltage regulator circuit. This can produce a rock solid DC in the amp but it also costs more to implement.

Having said all this, my B-15N has been modified to produce no audible hum. It doesn’t have DC heaters, just plain old AC. This is achieved through isolation and careful ground layout. So an amp can be well suited for studio work without using DC heaters.

A smart company would market an amp designed from the ground up to be quiet enough for studio work. But that market is small and it would be admitting that their other amps are flawed.
 
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