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Ampeg PF-50T - Extra volume with a Power Amp?

sadwinkey

sadwinkey

Aug 12, 2017
32
32
#1
Hey everyone!
So first off, I am not technically inclined at all when it comes to amps. I have only ever used combo amps, so I've rarely ever had to plug an amp into a speaker. So my apologies upfront if this is a dumb question!

So I recently ordered a PF-50T along with a 210AV cab. Generally, this will be used for practice with a very tame drummer who isn't too loud. It will also be occasionally used in a studio setting for recording.

From time to time though, on rare occasions, I will need more power (for outdoor gigs).

I've read a few posts on this forum that mention running a power amp along side the PF50T due to its lack of power. I'm interested in trying this, but I don't know if I'm going about this in the right way.

So currently, I have a Crown XLS 202 Power Amp laying around(I know this is a low-end amp, and not the best option), and I also have an ampeg pr-410HLF Cab. I plan on setting the PF50t to 8 ohms, running the 210av(an 8ohm cab) from the PF50t as normal, then run from the Transformer Line Out of the PF-50T into the Crown Power Amp(I don't see an ohm switch on this - Not sure how to set the Ohms), which would then be plugged into the PR-410HLF(a 4 ohm cab). Is this the right way to go about this, or am I even in the ballpark?

Thanks!
 
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#2
It's a stereo amplifier (2 separate amps) so you have a lot of options.

Here's the manual:CROWN XLS 202 SPECIFICATIONS Pdf Download.

Here are the power ratings by ohm:

Crown Screen Shot 12 03 2019.jpeg


Maybe @agedhorse or @Wasnex or @two fingers might stop by and figure you out for it. :)
 
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#3
Have you tried just cranking the PF50T through the 410 to see/hear what happens? I gig with an Epifani UL410 cab and an Ashdown LB30 (which is a THIRTY watt tube head) and it gets stupid loud.

More speakers will net you a lot more volume than more watts will.

Hook that amp up to the 410 and let it eat. You'll likely be surprised.
 
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#7
two fingers said:
Have you tried just cranking the PF50T through the 410 to see/hear what happens? I gig with an Epifani UL410 cab and an Ashdown LB30 (which is a THIRTY watt tube head) and it gets stupid loud.

More speakers will net you a lot more volume than more watts will.

Hook that amp up to the 410 and let it eat. You'll likely be surprised.
Click to expand...
So It's supposed to arrive tomorrow! I will be trying it out then with the 4x10. But from what I've read, there seems to be lots of people with volume issues with this amp in outdoor/larger gigs.

two fingers said:
Plus, I can't believe @Stumbo didn't mention this, but put an HPF in front of the amp and it will clean up that HLF cab and allow the amp to concentrate its energies on more usable frequencies. I have a 610HLF and it can get a little boomy. But my HPF cleans it up nicely.
Click to expand...
I'll definitely try this! Any advantage to doing this instead of just rolling off the tone knob a bit?
 
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#8
sadwinkey said:
So It's supposed to arrive tomorrow! I will be trying it out then with the 4x10. But from what I've read, there seems to be lots of people with volume issues with this amp in outdoor/larger gigs.


I'll definitely try this! Any advantage to doing this instead of just rolling off the tone knob a bit?
Click to expand...

Yes. Rolling off the tone knob "cuts highs". Using an HPF does the opposite, and uses a different method. But, in essence, it chops off sub low frequencies. It's really hard to explain. You have to hear it for yourself. But it just cleans things up. It doesn't make your bass sound weak (unless you adjust it to a frequency that is too high). Check out the epic @Stumbo thread on tue subject.
 
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#11
sadwinkey said:
Whats the difference between the transformer balanced out and the preamp out?
Click to expand...

Tranny out is after the power tubes and output transformer but it is still somehow at a DI level. It’s always post EQ as well. Not switchable like the preamp out.

The REALLY cool thing is that you can use the power amp like a load box. Bump the gain AND the volume on the PF 50 but use the power amp volume control to keep it from getting too loud unless you want it loud.

Allows you to get power tube growl without destroying your ears or causing an earthquake. I actually discovered this approach when running from the tranny out into my headphone amp.
 
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#13
Doner Designs said:
Tranny out is after the power tubes and output transformer but it is still somehow at a DI level.

The REALLY cool thing is that you can use the power amp like a load box. Bump the gain AND the volume on the PF 50 but use the power amp volume control to keep it from getting too loud unless you want it loud.

Allows you to get power tube growl without destroying your ears or causing an earthquake.
Click to expand...

Oh cool! That will be interesting to experiment with.
 
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#17
Some limiting factors. The sensitivity rating of the XLS202 is 1.25V at 4 ohms. In other words 1.25V RMS is required to drive the amp to full power when it is hooked up to a 4 ohm speaker. I don't believe the PF50T manual mentions how hot of a signal is available at the Preamp Out or Transformer Balance Out. Hopefully it will deliver at least 1.25V RMS.

Your 210AV is rated for 200W at 8 ohms. The cut sheet from Crown shows the XLS202 is rated for 200W average power at 8 ohms at 1khz, both channels driven. This is a relatively good match IMHO.

Your PR410HLF is rated for 600W at 4 ohms. The cut sheet from crown shows the XLS202 is rated for 300W average power at 4 ohms at 1khz, both channels driven. 300W is a decent amount of power.

The minimum load for bridge operation is 8 ohms, so you can't bridge the amp into the PR410HLF because the impedance is too low. Bridging the amp into the 210AV is possible but you would have enough power to destroy the speaker as the amp is rated for 600W average power at 8 ohms at 1khz in bridge mode.
 
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#19
Wasnex said:
The minimum load for bridge operation is 8 ohms, so you can't bridge the amp into the PR410HLF because the impedance is too low. Bridging the amp into the 210AV is possible but you would have enough power to destroy the speaker as the amp is rated for 600W average power at 8 ohms at 1khz in bridge mode.
Click to expand...

Thanks for the detailed response!
So if I didn’t bridge the two channels on the crown, and run a signal from the transformer out of the pf50 into a single channel of the crown, then from that channel’s output into the pr-410hlf, would that work? (While simultaneously running the 210av from the pf50’s speaker out)
 
#20
sadwinkey said:
Thanks for the detailed response!
So if I didn’t bridge the two channels on the crown, and run a signal from the transformer out of the pf50 into a single channel of the crown, then from that channel’s output into the pr-410hlf, would that work? (While simultaneously running the 210av from the pf50’s speaker out)
Click to expand...

You can run both sets of speakers this way with no problems. The only wild card that I can't answer is if the signal coming out of the PF50T will be hot enough to driver the power amp hard enough so you can match levels between the 210AV and PR410HLF. I believe there will be enough output, and you will need to turn the power amp down a bit using the front panel attenuators on the power amp.

One final issue to resolve may be absolute phase or polarity. Hopefully it works out so the speakers are working in phase. If not, you could use an XLR phase reverse adapter PHASE REVERSE - Catalog - Whirlwind
 
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