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Portaflex cutting out poll
- Thread starter ics1974
- Start date
I got my PF500 and PF210HE about a month ago. It has worked just fine, but did cut out when pushed really hard. Normal loud levels are just fine, but fully cranked it will go into protection mode. To me that's normal. I really like the tone but im wondering what adding a PF115 would do?
Hard to say as you need to decide if you like the tone of the 2 cabs together. You'd be running the amp at 4ohms giving the full wattage capable from the amp. My guess would be you wouldn't need to crank the amp to be heard as the additional cab will give you more fullness and some additional db's.
It should not and that is not normal. If it is normal then the amplifier is flawed and only works for those with low volume requirements. I play 125-175 gigs a year right now depending on the year. I've had this amplifier for two of those years. I have had a large variety of gigs to try this amp at, many with different volume requirements. I honestly feel after a few years with mine that it is not a loud amplifier and it goes into protection far too often. I consistently run my master at 3-4 o'clock and have to crank the pre-gain past 2, but after having the amp cut out so often I am a red-light nazi. Never into the clip on the preamp. Typically I can hear distortion coming from the power amp section at any given time, all it takes is a good dig in. This situation doesn't get better using the compressor.
In a given year my PF-500 cuts out 1/20 gigs, if not more like 1/18. I have had two of the PF-500's; a revision C00 and now a rev D00. Both cut out identically. I'm sick of people calling my demands on this amplifier too high; the amplifier is flawed IMO. And again; I have had mine on a bench test and I'd be willing to say that this amplifier has to try hard to deliver 300w at 4 ohms. If you let the distortion climb to 10% it does 380.. one should not have to babysit the controls of an amplifier this much to ride some imaginary line where cut outs happen and cutouts don't.
Now If only my car could stop breaking down and I could afford to put a roof over my kids heads then I could probably replace this amplifier but everybody has priorities. Thankfully there is a JBL/Crown PA covering me now..
okcrum
in your chest
There's nothing to sort out. It's a budget class D design going into protect mode. If you hit it consistently, you need either more power or sub-4 ohm capability (perhaps only at some frequency), due to your particular cabs. It has also been covered in other threads, on other brands of class D amps as well as Ampeg.
EDIT: A third alternative is to go to more mature class D designs that handle these conditions better. There's a reason you pay twice as much for a G-B or Aggie Class D. Those guys sit around, thinking about what could go bad on a gig, and design for it. Then, I know a number of them who gig their designs first, because there's nothing like eating your own dog food to fix a design. That's the price difference between them and some regular guys in a lab somewhere designing regular amps.
Disagree. First thing to sort out; the amplifier is not 500w @ 4 ohms @ 1% THD. 2nd is the fact that it lacks a good HPF and limiter design so it has to go into protection. I'd much rather sacrifice the sub frequency lows (which ampeg speakers cannot produce anyways) and hit a hard output wall than be able to clip a power amp and cause the amp to cut out. Ampeg simply under-designed this preamp and did not implement the power section correctly. This is what I learned from the "other thread."
Not really what was said in the other threads. it was far more complex than that; and it still lacked a good excuse for why Ampeg PF series have more issues than Genz or Tecamp. How do you define "hit it consistently." I argue that people are placing unreasonable low volume requirements on the PF-500 in order to avoid cut-outs: especially given its spec sheet.
I'm also not sure what the point of comparing a $400 amplifier to a $1100 amplifier is; which is what the other threads did a bit of. More in line with a comparison is to find a similarly spec'd head in power and price and compare. for example, a LH-500 doesn't cut out and is a much louder sounding amplifier. They cost the same at retail. Both are "500W" amplifiers. Why should I compare a PF-500 to a Genz 600w or 900w product at all?
According to the owners manual from Ampeg it is 500w at 3% THD. Personally I'd like to see the 0.1% with a mention of the 5%
Mine also has a highpass (see image) at about 6dB/oct, I also have the prints and the limiter is closer to a clipper so ...
Another potential issue is that the majority of the components are 5% so the action of the various circuits is somewhat ... variable.
The LH500 has much more conservative specs (power is at 0.5% THD) than the PF and weighs in at bit more than double the weight (10.5kg vs. 5kg).
To be honest I wanted the PF800 (for the headroom) but the wife didn't want me to spend the extra cash.
edit: I should add that no problems so far for me but I've had it less than a month.
Edit again: And I did my math a bit wrong it is more like 12dB/oct or more - just don't have the resolution below 20hz for a better read.
Attachments
okcrum
in your chest
When I measured my two PF500s, they made rated power but were higher on THD, at around 2-3%. The preamp has nothing to do with this but for enabling you to dial it high enough to hit the power amp limiter, which is fugly sounding, just like an early G-K (MB500) I tried was. Difference is, the Ampeg goes silent and the G-K sounded like trash. The compressor knob on this amp is really your friend if you want to push it.
See above and my edit. Buy the LH-500 if you like it better. I've cranked my PF-500s without limiter or protection cutouts (and I know I can induce them), and they're from two of the early, most whined about batches. I'm talking too loud for two guitar players w/50w each cranked. These amps easily do fill on a large stage where there's PA support. The price was right for me at the time given the tone, the power, and the limitations of the amp.
The PFs were a next-gen budget design when they came out, and now the world has caught up. We'll see if Ampeg's learned some things (as did everyone else making cheap class Ds) in their 2nd round with the PF-800. They've had enough time.
That looks more to be a 24db/octave HPF set at 40hz.
Oh goodness that frequency response curve is a big reason why I dislike my tone. No wonder I cannot stand to run the amp without the low eq curve set below 9 o'clock. Why did they HPF at 40hz but boost 40-80hz about 3db?
Never said I did like it more, I just used it as an example of a true-to-spec 500w amp at the same price point. The spec sheet tells me the LH-500 is a true 500w amp and my ears confirm it preamp differences aside. Who cares about the extra few lbs if the thing delivers; especially if it doesn't cut out. 2-3% THD to me is like asking too much out of an amplifier, and my ears tell me mine is pushing more like 10% THD on the loudest of peaks.
I'm just saying I routinely push mine into audible distortion zones, the compressor makes cut-outs more likely to happen from experience, and the amplifier is still not pushing enough volume for my ears. A good deal of that might be the voicing of 3db boost between 40-80hz, which will eat available watts quickly making the amp feel mid shy when the limiter is getting hit.
Given that frequency response curve though I can see what is happening and what should be happening; but I'm not the engineer so I have no idea why they chose to waste so many of the watts pushing out frequencies that their own speaker cabinets cannot reproduce. But I also do not know how the frequency response plot was generated so its not definitive by any means; I just see what I see, a big boost from 40-80hz. Gross.
It should be noted that the response graph is 5dB/div not 10. The graphs I have are made with JAPA using an ART DualPre to the input of the amp and returning from the Preamp out. I'll post the graphs of the proofing tests if needed (the response was flat 20-20k).
FYI the response I got with the bass @ 9 is in the attached pic.
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Oh, I see you've discussed doing that already. Well is it important if the bass knob's at 9:00 as long as you're getting your sound?
Well 9 sounds anemic to me, and I can see it's because there is then a lack of 100-200hz content. Putting the mids at 3 o'clock with the switch on 2 seems to help some but its not what I really want.
Fascinating.
The EQ I usually use is 9-10 O'Clock lows, mids at 9 O Clock with the switch on 4, and the highs at 8 o'clock or 9 o'clock depending on the bass.
Fascinating.
The EQ I usually use is 9-10 O'Clock lows, mids at 9 O Clock with the switch on 4, and the highs at 8 o'clock or 9 o'clock depending on the bass.
I know you are a strong and vocal advocate for Ampeg gear Jimmy, and good for you, but I was the one who made the statement that you bolded. So, its seems pretty self evident that I do not think that 40% of ALL PF series buyers are having the issues reported here on TB.
It's just a mathematically accurate summary of the poll to date, and while the total numbers (probably) do not represent a statistically significant sample on the total global sales volume of this amp series, it does accurately depict the percentages of those on TB, who are self reporting problems.
I also have not claimed any "scientific" relevance to this poll (which I did not initiate), it simply lets TB users who have had problems tally up the actual numbers of those on TB who have had the reported problems.
I believe the intent of the Poll OP was to clarify the number of users on TB who were actually having the cut-out issue, and perhaps take that issue out of the regular PF300/500 mega thread.
geez. you guys are a touchy bunch.
did I happen to mention how much I like the PF500/115HE rig that I am trying out currently (hmm, yes, looks like I did)
and I will offer you peace as well Mr JM
You actually make more sense than most in this thread. Speaking as a happy Ampeg user, but also as a RL economist
+1
No discussion, just a technical type that likes graphs. I ran a full series to see just what the knobs and buttons do.
I thought about the LH500 a lot before choosing the PF500, the Ampeg's basic tone and controls are what won it for me. The tone stack controls weren't my cup-o-tea either, wanted less mid-scoop at noon. That's why there are other makes and models.
Got this head for my son new at GC. He gigged and practiced with this amp almost daily for 23 months then a week ago it just died. No fan, no output, fault light on. It's currently in for service, but I'm having second thoughts as to the reliability of this amp. So I'm thinking about new amp options. Good amp, yes. Great amp, no. Like that he can throw into a backpack and run off to band practice. Maybe keep it as a back up or sell it/trade it for something a bit more pro grade. I dunno.
I got the suspicion that when I dropped the head off at the authorized Ampeg repair facility, it was not the first one they encountered. But then they also said they worked on a lot of SVT gear too.
I got the suspicion that when I dropped the head off at the authorized Ampeg repair facility, it was not the first one they encountered. But then they also said they worked on a lot of SVT gear too.
okcrum
in your chest
I'm kind of tired of hearing things like "doesn't sound like 500 watts to my ears" and "sounds like 10% THD to my ears". I have actually measured 500 watts from both my PF500s at 4 ohms at a measured THD of 2-3%. So I'm not too concerned with either the spec sheets or ears. If I needed to be louder than I can get with these, I'd be looking at a 7pro or nice preamp with one or more kW class modern power amps. Why pussyfoot around?
Edit: to get on topic, only cutouts I've had have been from bad cables.
Edit: to get on topic, only cutouts I've had have been from bad cables.
