• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join free Log in
    Want zero display ads or expanded classifieds tools? Compare plans.

Ampeg PF-20T to (power) amp

#61
Zbysek said:
My understanding of the issue is that you need to convert ballanced signal to unballanced signal...some say
Click to expand...


Sometimes just using a hardwired XLR to 1/4" adapter cable works. Cables are not always wired properly, but may work depending on the topology of the balance output circuit.

Better to use a device with an isolation transformer. An Ebtech Hum Elimator XLR is a fairly low cost option.

Here's a page that explains [Invalid or Expired Link Removed]
Here a link to the Ebtech [Invalid or Expired Link Removed]
 
  • Like
Reactions: Wisebass and Zbysek
#64
Zbysek said:
My understanding of the issue is that you need to convert ballanced signal to unballanced signal...some say
Click to expand...

Ideally yes, but a balanced signal is just a divided unbalanced signal with one side inverted to take advantage of common mode rejection, so in theory you can just use one side i.e. the tip of a TSR or XLR pin 2 (I think) as an unbalanced signal. I have a neutrik converter that does just that, from XLR to mono jack. You get a slightly weaker signal of course.
 
  • Like
Reactions: Wisebass
#65
Engle said:
I just read through that thread paying close attention to what agedhorse had to say, and it still seems to come down to experimentation to see what works.
Click to expand...

I believe the inference is you need to know/understand the topology of the balanced circuit and configure the adapter appropriately. In some rare instances the sending equipment may be damaged if the adapter is configured improperly. Basically you need to be an engineer :(.

Pretty sure it's always safe to use an isolation transformer to make the conversion.
 
#66
Wasnex said:
I believe the inference is you need to know/understand the topology of the balanced circuit and configure the adapter appropriately. In some rare instances the sending equipment may be damaged if the adapter is configured improperly. Basically you need to be an engineer :(.

Pretty sure it's always safe to use an isolation transformer to make the conversion.
Click to expand...

This has been a go-to reference for many years: [Invalid or Expired Link Removed]
 
  • Like
Reactions: Wasnex and Wisebass
#68
Wasnex said:
The problem with sending Preamp out to the LM and Transformer Bal Out to FOH is you will not know how distorted the sound is at FOH. The Transformer Bal Out signal will be at least as distorted as the signal at the Preamp Out, potentially much more so. Definitely run some experiments :thumbsup:.
Click to expand...
Transformer balanced out to Markbass. Post EQ DI out of the Markbass to FOH ftw?
 
  • Like
Reactions: Wasnex
#70
Engle said:
Thanks! That Rane page is great. I've referred to it before for AV applications at work and will save it it my tech info folder.
Click to expand...

I remember when those Tech Notes were in paper hard copy.
Yel_wink.gif
 
  • Like
Reactions: agedhorse, Wisebass and Wasnex
#71
ficelles said:
Ideally yes, but a balanced signal is just a divided unbalanced signal with one side inverted to take advantage of common mode rejection, so in theory you can just use one side i.e. the tip of a TSR or XLR pin 2 (I think) as an unbalanced signal. I have a neutrik converter that does just that, from XLR to mono jack. You get a slightly weaker signal of course.
Click to expand...

1. I believe if the output is transformer or impedance balanced you connect pin 3 to Ring (ground) and pin 2 to Tip (hot). Connect the shield on the output connector only. If the output is transformer balanced, letting pin 3 float will not work because there is no path for the electrons to return to the transformer winding.

2. If the output uses a differential amp you may need to let pin 3 float to avoid shorting one side of the amp to ground and releasing the magic smoke. Connect the shield on both the output and input connectors. I think it's rare to find equipment that would be damaged by this. Some would work fine with the adapter in 1. above, but half the signal would be shunted to ground.

3. You also need to be aware that some older equipment had pin 3 hot instead of pin 2. For this equipment reverse the connections of pin 2 and pin 3.

I am not an engineer....please offer corrections if I have stated something inaccurately.
 
Last edited:
#72
Micro VR fx loop send to PF20T instrument input.
PF20T XLR to return to Micro VR.
If the set up this correct?
Which XLR it’s more appropriate to use?
The one on the right or the one on the left?
The PDF is a bit ambiguous .
 
#73
Graeme2 said:
Micro VR fx loop send to PF20T instrument input.
PF20T XLR to return to Micro VR.
If the set up this correct?
Which XLR it’s more appropriate to use?
The one on the right or the one on the left?
The PDF is a bit ambiguous .
Click to expand...

Do you mean, "How do you chose between Preamp Out, and Transformer Bal Line Out on the PF20T?"

It's really a matter of the sound you want. If you want to capture just the PF20Ts preamp sound, use Preamp Out. If you want power tube drive use Transformer Bal Line Out.

Take a look at the simplified schematic on page 13 of the manual (attached):
 

Attachments

  • Like
Reactions: chupacerveza
#75
Wasnex said:
Do you mean, "How do you chose between Preamp Out, and Transformer Bal Line Out on the PF20T?"

It's really a matter of the sound you want. If you want to capture just the PF20Ts preamp sound, use Preamp Out. If you want power tube drive use Transformer Bal Line Out.

Take a look at the simplified schematic on page 13 of the manual (attached):
Click to expand...

Preamp out is a lot hotter than balanced line out, in case that’s important.
 
  • Like
Reactions: chupacerveza, Wisebass, Zbysek and 1 other person

Latest posts

Top Bottom
Back