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Ampeg PF500/PF350 Pt II.5

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#41
ButtUglyJeff said:
You can run 2 8ohm cabs. I use 2 PF115s, one daisy chained to the other with 1/4". The only critique I have is that the PF500 has one Speakon, and one 1/4". The 7Pro has 2 Speakons...
Click to expand...

I admit my ohms knowledge is a little rusty, but I'm curious... If you're daisy chaining your cabs (running them in series), you're getting everything out of the amp that you could. The PF500 with two 8ohm cabs in series creates a 16ohm load, upping the resistance to and lowering the amount of power from the amp. If you run them in parallel (yes, using the speakon for one and the 1/4" for the other), you'd get a 4ohm load and the full 500 watts from the amp.

(anyone can feel free to confirm or correct me on this, I'm definitely not an expert. :))

Is there any particular reason you daisy chain, rather than run them in parallel? Do you just not like Speakons that much? Lol (sorry, couldn't resist ;))

5sg.
 
#42
rllefebv said:
Yes, but you will have to daisy-chain them or run one with a 1/4" and the other with a SpeakOn... Just don't go below the 4 ohm minimum...

-robert
Click to expand...

Daisy chaining vs. using both outputs are pretty different things... Series vs. parallel, if I'm remembering correctly. See my comment above. Running two 8ohm cabs in parallel will make the amp "see" a 4ohm load, where running the same cabs in series (daisy chained) will create a 16ohm load. Higher ohms = more resistance, more resistance = less power from the amp.

The PF500 is rated at 300 watts @ 8ohms, 500 watts @4ohms. I would imagine that at 16 ohms, it's maybe 200 watts-ish? That's just a guess though. The power is divided equally between the cabs, so how you connect the speakers to the amp makes a big difference... 75 watts to each cab in series, versus 250 watts apiece when running parallel.

5sg.
 
#43
fivestringgecko said:
(anyone can feel free to confirm or correct me on this, I'm definitely not an expert. :))

Is there any particular reason you daisy chain, rather than run them in parallel? Do you just not like Speakons that much? Lol (sorry, couldn't resist ;))

5sg.
Click to expand...

I am no expert either, but I believe you are mistaken, the ohm ratings will not change if you wire in parallel vs series.

i can see daisy chain useful for powering more cabs than there are outputs for cabs. ie a 2 ohm head and 4 8 ohm cabs, I am sure there are more uses as well like saving on buying longer cables haha
 
#44
fivestringgecko said:
I admit my ohms knowledge is a little rusty, but I'm curious... If you're daisy chaining your cabs (running them in series), you're getting everything out of the amp that you could. The PF500 with two 8ohm cabs in series creates a 16ohm load, upping the resistance to and lowering the amount of power from the amp. If you run them in parallel (yes, using the speakon for one and the 1/4" for the other), you'd get a 4ohm load and the full 500 watts from the amp.

(anyone can feel free to confirm or correct me on this, I'm definitely not an expert. :))

Is there any particular reason you daisy chain, rather than run them in parallel? Do you just not like Speakons that much? Lol (sorry, couldn't resist ;))

5sg.
Click to expand...

If you run one cable to one cab and then a second cable from cab to cab, that is the same as running two cables from the head to two different cabs. Both scenarios result in a 4-ohm load (if you are using two 8-ohm cabs).
 
#45
Doll said:
I am no expert either, but I believe you are mistaken, the ohm ratings will not change if you wire in parallel vs series.
Click to expand...

The thing is, both of those scenarios above are the same (parallel, I believe). In order to run in series, you'd need a special cable that has three "ends" to it (amp, cab, and cab), and in that scenario, two 8-ohm cabs would present a 16-ohm load.
 
#48
fivestringgecko said:
Is there any particular reason you daisy chain, rather than run them in parallel? Do you just not like Speakons that much? Lol (sorry, couldn't resist ;))

5sg.
Click to expand...

I like Speakon, I just don't like paying for them....

Ampeg gave me very decent 1/4" cables with both cabs. That's the only reason I'm using them in daisy chain.

The PF500 only has 1 of each connector, so expect most Portaflex owners to daisy chain one way or another. If I had an SVT-CL, I'd definitely go parallel with Speakon, just to protect the amp.
 
#50
Hey all

If somebody could have a look at their mounting hardware for attaching the head to the fliptop and answer a couple of questions for me, I'd appreciate it.

First what is the length of the replacement screws used to attach the top to the board? Secondly, what is the thickness of the board itself?

Thanks

Keep Low :bassist:
 
#51
tombowlus said:
The thing is, both of those scenarios above are the same (series, I believe). In order to run in parallel, you'd need a special cable that has three "ends" to it (amp, cab, and cab), and in that scenario, two 8-ohm cabs would present a 16-ohm load.
Click to expand...

Are you sure about that? I'm pretty sure the first option is parallel. Two 8 Ohm cabs in parallel = one four-ohm load for max power.

A 16 ohm load would result from the second option, which is series.
 
#52
John D said:
Are you sure about that? I'm pretty sure the first option is parallel. Two 8 Ohm cabs in parallel = one four-ohm load for max power.

A 16 ohm load would result from the second option, which is series.
Click to expand...

I am solid on my reasoning, but less so on my nomenclature. :smug: :D
 
#53
John D said:
Are you sure about that? I'm pretty sure the first option is parallel. Two 8 Ohm cabs in parallel = one four-ohm load for max power.

A 16 ohm load would result from the second option, which is series.
Click to expand...

This may help you, if you use 1 output from the head with both cabs the load would be 4 ohms...as long as both cabs are 8 ohms..

If you use both outputs 1 per cab the load will be 4 ohms.
Here is the PF owners manuel....page 7 and 14..
[Invalid or Expired Link Removed]
 
#54
lowendrv said:
This may help you, if you use 1 output from the head with both cabs the load would be 4 ohms...as long as both cabs are 8 ohms..

If you use both outputs 1 per cab the load will be 4 ohms.
Here is the PF owners manuel....page 7 and 14..
[Invalid or Expired Link Removed]
Click to expand...

I'm pretty sure that's what I said. Either way, they are in parallel. The only way to get series is to rewire the cabs or make a special cable set.
 
#58
Fun gig last night with the Hobohemians -- on upright into my PF500/PF115 (via K&k BassMax).
Link Removed Plenty of strong, articulate and creamy bass with gain and master around noon. Compressor around 11:00. Some bass and low mids rolled off and treble around 2:00. Also took a wee bit of amp DI (pre eq) into the PA for good measure. Lots of compliments. First gig with these guys and it was a blast.
 
#59
Yep, it's even more clear in the manual for the cabinet. Guess it's pretty obvious that I didn't read the manual, huh? lol

[Invalid or Expired Link Removed] (see page 3)

Okay, so now that we've played that discussion out and came to the definite conclusion that daisy chaining does in fact make a 4ohm load... :p:D;):hiding: lol

Here's another question (hopefully it hasn't been gone over in the old threads that I haven't had a chance to make it all through yet):

Is anyone having problems with the tolex lifting up? I've noticed that some of the seams are starting to lift/loosen, particularly on the top panel with the amp. Should I just get some tolex glue and re-stick it?

5sg.

IMAG0975.jpg
 
#60
60bass said:
Hey all

If somebody could have a look at their mounting hardware for attaching the head to the fliptop and answer a couple of questions for me, I'd appreciate it.

First what is the length of the replacement screws used to attach the top to the board? Secondly, what is the thickness of the board itself?

Thanks

Keep Low :bassist:
Click to expand...

By replacement screws I'm assuming the longer screws for attaching the amp to the lid? If that's the case then they are 1 1/2". The lid looks like 11/16" thick. (1/2" birch ply with the tolex wrapped around it)

Hope that helps...
 
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