Official Ampeg Portaflex Club

#36,101
lookah said:
Excellent points. I'm now indeed inclined to stick with the modern cab I ordered and try it out -- as AMPEG intended -- with the pf20-t and if I want a SB12 I'll get the full combo as AMPEG also intended...
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The PF-20T that I had for a short while had Gold Lions in the output section, so I don't know how they sound with stock tubes. I played it for months in my living room and testify that it is a gorgeous sounding amplifier. Anymore,
I prefer an amp that is in current production rather than getting a vintage specimen up to par, but that's me. I've gotten somewhat lazy over the years. ;)
 
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#36,102
Porterx said:
My Portaflex PF 50t went down. There’s no sound coming from the bass. It powers up and you can take it off standby (purple light comes on and light hum) but no sound. The only thing I did to it out of the ordinary was I forgot and left it on standby several hours when I went out to mow grass and do yard work, but when I came back in I played it and it was fine. But, when I turned it on the next day, I had no sound as described above. I don’t think it’s the bass or the cab (Ampeg 4x10 HLF Classic), because I hooked up everything to my SVT and they were fine. Since I bought it be a few weeks ago, I took it back to the music Store I purchased it from, and he’s going to get it checked out. I will let everyone know when I hear back from him.
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Leaving it in standby for several hours will not cause any damage. You didn’t do anything wrong. You could have tried to reseat your tubes. Otherwise, swap out the small tubes one at a time, then the pair of power tubes and set the bias. Those are the simple things. Hopefully the store will quickly sort it out for you.
 
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#36,103
beans-on-toast said:
Leaving it in standby for several hours will not cause any damage. You didn’t do anything wrong. You could have tried to reseat your tubes. Otherwise, swap out the small tubes one at a time, then the pair of power tubes and set the bias. Those are the simple things. Hopefully the store will quickly sort it out for you.
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Thanks for the reply! That will be great if that’s all it is. I’ll post when I hear back.
 
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#36,104
So reading the Sushi Box thread, I just found out that 12DW7 tubes exist? 1/2 12AU7, 1/2 12AX7 - would this be a good way to cut down on drive/distortion in my PF50T while retaining a good amount of volume if I stick it in V1? On the amp itself, V1 is labeled "Preamp/Gain" and V2 is labeled "EQ/Amp Drive", despite the fact that when I replaced V1 with a 12AU7 (as originally posted in this thread while ago, which was a GRRREAT clean sound!) it had basically no drive even cranked to 11 on both the input gain and the master (though obviously there is a big volume reduction). Could a 12DW7 circumvent this volume reduction? According to the block diagram, it isn't labeled exactly where V1 and V2 are in the circuit itself, it just says "12AX7" for either of the preamp tubes. Would this be a way to get the best of both worlds of, of higher volume and very little drive/distortion? (I'm probably going to purchase a 12DW7 anyway for funsies, but figured I'd ask the knowledgeable guys in here too.)
 
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#36,105
LSM07 said:
So reading the Sushi Box thread, I just found out that 12DW7 tubes exist? 1/2 12AU7, 1/2 12AX7 - would this be a good way to cut down on drive/distortion in my PF50T while retaining a good amount of volume if I stick it in V1? On the amp itself, V1 is labeled "Preamp/Gain" and V2 is labeled "EQ/Amp Drive", despite the fact that when I replaced V1 with a 12AU7 (as originally posted in this thread while ago, which was a GRRREAT clean sound!) it had basically no drive even cranked to 11 on both the input gain and the master (though obviously there is a big volume reduction). Could a 12DW7 circumvent this volume reduction? According to the block diagram, it isn't labeled exactly where V1 and V2 are in the circuit itself, it just says "12AX7" for either of the preamp tubes. Would this be a way to get the best of both worlds of, of higher volume and very little drive/distortion? (I'm probably going to purchase a 12DW7 anyway for funsies, but figured I'd ask the knowledgeable guys in here too.)
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I don’t know. You can try it and see. It won’t harm the amp. If the EQ wiring gets the 12AX7 triode half it could be more distorted because of higher gain. If the phase inverter (driver) gets the 12AX7 half the amp might not be as loud because it has less current drive.

I’d try a 12AY7/6072 in V1. It will have more gain than a 12AU7.
 
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#36,106
LSM07 said:
I just found out that 12DW7 tubes exist?
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Exist, but maybe hard to find? I know my tech did a mod to my ‘73 SVT so that 12ax7’s could be used in place of most (or all) of the 12DW7’s that originally came with it, citing that the 12DW7’s had not been made in a long time and they were getting harder to find. That was back in 2016.
 
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#36,107
Ringhammer said:
Exist, but maybe hard to find? I know my tech did a mod to my ‘73 SVT so that 12ax7’s could be used in place of most (or all) of the 12DW7’s that originally came with it, citing that the 12DW7’s had not been made in a long time and they were getting harder to find. That was back in 2016.
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They are available as reissues made for JJ and EHX.

Search results for "12dw7"

www.thetubestore.com www.thetubestore.com
 
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#36,108
Hola y’all. I have a PF20t/112HLF amp that I would like to use at my church for low volume monitoring and DI. I would be playing 3 songs then the pastor speaks for 30 to 40 minutes then the team finishes with 1 to 2 songs. My question is would it be ok to leave the amp on standby for 40 minutes? The sanctuary stays at a reasonable temperature and no direct sunlight on the amp.
 
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#36,111
Have any of you guys tried both a Shaw B-150 and a B-15R? I'm assuming that the B-150 sounds more similar tone-wise to the B-15N, but asking as I may upgrade to one of those when I get a chance. There's a B-15R for sale not far away from me, but I may spring for the B-150 as it has caught my eye as well.

Also, my order of 12DW7 and its reverse-compliment ECC823 should be in today, will post results with my PF50T when I get a chance (the idea being to see which of the two tube configurations will allow for more volume with less overdrive through the amp).
 
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#36,112
LSM07 said:
Have any of you guys tried both a Shaw B-150 and a B-15R? I'm assuming that the B-150 sounds more similar tone-wise to the B-15N, but asking as I may upgrade to one of those when I get a chance. There's a B-15R for sale not far away from me, but I may spring for the B-150 as it has caught my eye as well.

Also, my order of 12DW7 and its reverse-compliment ECC823 should be in today, will post results with my PF50T when I get a chance (the idea being to see which of the two tube configurations will allow for more volume with less overdrive through the amp).
Click to expand...

I haven’t tried a B-150 but it looks interesting.
 
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#36,114
LSM07 said:
Alright, well, the tubes came in.

Tube 1: ECC832 (12DW7)
Per the box:
Triode 1 gain: 25
Triode 2 gain: 90

Tube 2: ECC823
Per the box:
Triode 1 gain: 95
Triode 2 gain: 30

EDIT: More playing needed to offer my findings!
Click to expand...

It demonstrates that tubes are not consistent, nor are they ideal as per the data sheets. Gain is also affected by the circuit that they are in.
 
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#36,118
LSM07 said:
Alright, well, the tubes came in.

Tube 1: ECC832 (12DW7)
Per the box:
Triode 1 gain: 25
Triode 2 gain: 90

Tube 2: ECC823
Per the box:
Triode 1 gain: 95
Triode 2 gain: 30

EDIT: More playing needed to offer my findings!
Click to expand...

TL;DR: If you want more volume but less drive, stick a 12DW7 in V1.

OK, so now that I've had some time to sit on it, the 12DW7 is the best of all worlds with respect to volume-to-overdrive, after comparing with the ECC823 (easier to overdrive but lower volume, which may be useful for some people), 12AU7 (clean but much quieter), 12AY7 (slightly louder but overdrives much easier), and 12AX7 (bog-standard). I also found that I had a Mesa 12AX7-A sitting around for some reason, and it sounded fabulous in V1, but of course overdrives too soon for my taste. The low-to-high gain of the 12DW7 allows to get very loud before overdriving, however I find that the tube itself is not as clear as some others I was testing against - perhaps the character of the individual tube itself versus other 12AU7 tubes, so I may fork over some cash for a NOS 12DW7. Also, that Mesa 12AX7-A got put into V2.

Now to fix the annoying rattle in V5 👀
 
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#36,120
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