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Peavey IPR 1600 - INTERNAL PHOTOS

#81
GKevinK said:
Calling attention to the voltage swing capabilities of an amp really reminded me of a time long ago and a neat trick we used with Phase Linear power amplifiers. They used transistors which *loved* to run at higher voltages (and the power supply of the amp allowed that). We used to run pairs of JBL L100 speakers in series on each side to present a 16 ohm load to the amp, and it would KILL. The readings on the big meters on the front of the amp wouldn't be useful any more (you could slam the meters against the right side way before you'd hear any clipping)... which would freak out the club owner (I was a club DJ at the time). Something about the transistors available in those days (we're talking early to mid 70's) being more designed for high voltage applications, like TVs or something I guess.
Click to expand...

Sort-of, kind-of, but not really...

I assume you are talking about the 400's and 700's here.

Back in "the day", high voltage transistors were very expensive and really not very available in PNP. In order to achieve the voltage swings that were necessary to deliver as much power as the amps did required power supplies of +/-75V and in the case of the 700 it was +/- 100 volts. This means that the transistors must have a CE breakdown rating of (minimum) 150 or 200 volts. These were special transistors at that time and fairly low safe operating area compared with today.

So, what was happening with a speaker like the L-100, which was a low power handling speaker (real world power of about 125-150 watts RMS) was that when driven in parallel on a channel of the 700, that would be about 350 watts RMS and because of the way the power supply was sized, could deliver almost 500 watts RMS under short term. This would shove the woofer VC pretty far out of the gap and the DC resistance of the driver would dominate and the impedance would fall and the amp would limit the current sounding like bad clipping. Still better than blowing up. The power compression would prevent the speaker from getting any louder and the excess power just heated things up.

When running the speakers in series, there was no chance of VI (current) limiting and the speakers were operating closer to their rated power, meaning they stayed in their gaps and did not enter power compression. The amp ran cooler too, a LOT cooler. The 700 could deliver maybe 250-300 watts into 16 ohms, which was a perfect match for the speaker.

I was pretty familiar with the Phase Linear line as I ran a warranty center back in the late 70's and early 80's. Things are much better from an amp design perspective these days, technology has brought us better parts and better designs, but this was a big stepping stone for pro audio.
 
#85
i think we all seen this coming . they share a ton of gear between the companies . im sure there are a few differences here and there , but alot of the products look like theve simply been rebadged ... not a bad thing at all to me because i am a huge peavey fan and also liek crest ...win win to me .
 
#87
Class D has been a big influence in moving powered enclosures closer to the forefront for years now too. I expect that to continue.

Peavey also introduced some real nice Impulse and Euro powered enclosures at NAMM that probably will eclipse the performance of way spendier products of just a few years back.
 
#88
Nice stuff, there's a whole herd of new lightweight amps coming this year. There's also the new Crown XLS series, with DSP (kind of like a simplified XTi). And the Behringer EPQ series, e.g. the EPQ1000: 1u shallow and light, 2x500 4ohm. And EPQ304: 4 channels in 1u which would be nice for monitors.

I may need an extra power amp later this year, I now find it's a good thing the budget didn't allow me to purchase one last year :cool:
 
#89
The club I worked in had 2 x 700b and 2 x 400 for the mains, and an additional 400 for the glassed-off dj booth. Normally, one pair of L-100 speakers served as booth monitors, and the 400 drove them fine under normal circumstances. The manager of the club had an additional matching pair of L-100's upstairs in the club (in his apartment), which he brought down into the booth for awhile - setting them up in the series connection to run at 16 ohms on the 400. The difference compared to the single pair was really remarkable... it went *way* louder, while at the same time sounding like it wasn't being stressed at all (other than the visual indication of the needles on those big meters bouncing off the right side.)

At least those are my 30+ year old memories of it. :) Interesting note about the power handling of the L-100 and the gap transits.

agedhorse said:
Sort-of, kind-of, but not really...

I assume you are talking about the 400's and 700's here.

Back in "the day", high voltage transistors were very expensive and really not very available in PNP. In order to achieve the voltage swings that were necessary to deliver as much power as the amps did required power supplies of +/-75V and in the case of the 700 it was +/- 100 volts. This means that the transistors must have a CE breakdown rating of (minimum) 150 or 200 volts. These were special transistors at that time and fairly low safe operating area compared with today.

So, what was happening with a speaker like the L-100, which was a low power handling speaker (real world power of about 125-150 watts RMS) was that when driven in parallel on a channel of the 700, that would be about 350 watts RMS and because of the way the power supply was sized, could deliver almost 500 watts RMS under short term. This would shove the woofer VC pretty far out of the gap and the DC resistance of the driver would dominate and the impedance would fall and the amp would limit the current sounding like bad clipping. Still better than blowing up. The power compression would prevent the speaker from getting any louder and the excess power just heated things up.

When running the speakers in series, there was no chance of VI (current) limiting and the speakers were operating closer to their rated power, meaning they stayed in their gaps and did not enter power compression. The amp ran cooler too, a LOT cooler. The 700 could deliver maybe 250-300 watts into 16 ohms, which was a perfect match for the speaker.

I was pretty familiar with the Phase Linear line as I ran a warranty center back in the late 70's and early 80's. Things are much better from an amp design perspective these days, technology has brought us better parts and better designs, but this was a big stepping stone for pro audio.
Click to expand...
 
#90
I ordered one about a month ago to be used as the main amp in our PA system. We play mostly small clubs so the plan was to run the mains through one channel and the subs through the other. We've used this set up before with a Peavey 1500 amp without a hitch.

I fired up the amp as soon as I got it and it worked like a charm. Last night was our first time using it live. I set the limiters to 40 volts on the subs and mains, even though we normally don't use half that voltage. Sound check went perfect, the sound was clear and loud, no problems. Half way through the first set we lose sound through our mains (but not the subs). I checked all the connections, the mixer settings, and everything else I could think of but nothing. Then magically the sound came back. We get through a couple more songs and it happens again. Then I notice the temperature light is glowing on the amp (on just one channel). So obviously we're overheating the amp, even though the attenuators are turned half way up and the main faders are not reaching unity gain.

I suspect the fan is probably not working, but why would only one channel overheat? Anyways, I'm going to run it today to see if the fan is working and if not it's going back. The moral of this story: don't wait for a gig to try this amp out. I should have ran it hard during a practice to make sure it was working fine, but I have never had an amp cut out because of overheating. I ran my old PV-8.5C at 10V for 24 hours and other than the fan periodically running fast it worked like a charm. I'm not bashing this amp, just run it through its paces first before using it live.
 
#91
The amp is interesting..... THERE IS NO HEATSINK for any device visible, past the area of PWB trace around the power devices, which appear to be the 4 devices with the white on them near the toroid inductors. The devices someone inquired about are likely rectifiers. There seem to be no other power devices underneath, etc

With available high current mosfets, that type design is quite possible*, but may have some drawbacks in terms of ability to really "beat on" the unit. It probably accounts for the overheating mentioned.

That design is the same scheme as the original small class-D amps sold into the MI market, which were not very reliable, but did work. Their problem was not always with heatsinking.


billfitzmaurice said:
One must understand what bridging does to know if it's of any value to them. What it does not do is increase your available current. It doubles your available voltage swing. If the available voltage swing of one channel is adequate to drive your cab to full output then you get no benefit from doubling it. In the vast majority of cases bridging is only useful for driving 8 ohm or higher loads. And if the entire voltage/current/power/impedance thing sets your head to spinning you definitely do not want to bridge. The downside of bridging is that the doubled voltage swing quadruples the possibility of you toasting your speakers.
Click to expand...

Nonsense.

That is extremely constricted thinking.

Power in excess of the speaker rating has positive benefits in headroom, clipping, etc.

Trying to think of MI performance in terms of the data sheet specs only is non-productive. For one thing, xmax is a spec, but the required cone movement for a given power varies with frequency. Through a LOT of very useful audio range, xmax etc is NOT AN ISSUE.

And, "RMS based power" is NEVER an issue with MI, where the average power NEVER approaches the amp "RMS" in use. (EDIT guitar usage with overdrive is an exception, bass or PA is not)

Limiting amp power on a speaker voltage basis will just result in clipping, bad sound, low volume, etc.

I know Bill is a respected guy, but I am sorry to say that his approach here is simply NOT a useful way to think about the power issue.

* The current crop of mosfets have very low conduction losses, and increase power losses very little with output current. most of the losses are switching losses, that vary only a relatively small amount with power level in the ideal case. At this voltage level, IGBTs are a non-starter, with far higher losses.
 
#93
chunkylover73 said:
I ordered one about a month ago to be used as the main amp in our PA system. We play mostly small clubs so the plan was to run the mains through one channel and the subs through the other. We've used this set up before with a Peavey 1500 amp without a hitch.

I fired up the amp as soon as I got it and it worked like a charm. Last night was our first time using it live. I set the limiters to 40 volts on the subs and mains, even though we normally don't use half that voltage. Sound check went perfect, the sound was clear and loud, no problems. Half way through the first set we lose sound through our mains (but not the subs). I checked all the connections, the mixer settings, and everything else I could think of but nothing. Then magically the sound came back. We get through a couple more songs and it happens again. Then I notice the temperature light is glowing on the amp (on just one channel). So obviously we're overheating the amp, even though the attenuators are turned half way up and the main faders are not reaching unity gain.

I suspect the fan is probably not working, but why would only one channel overheat? Anyways, I'm going to run it today to see if the fan is working and if not it's going back. The moral of this story: don't wait for a gig to try this amp out. I should have ran it hard during a practice to make sure it was working fine, but I have never had an amp cut out because of overheating. I ran my old PV-8.5C at 10V for 24 hours and other than the fan periodically running fast it worked like a charm. I'm not bashing this amp, just run it through its paces first before using it live.
Click to expand...

If you look at the pictures provided by Gastric at the beginning of the thread then you might see that the two channels of the amplifier are split front to back.

One of the channels along with its power devices sits behind the piece of cardboard used to 'direct airflow' and will therefore receive the 'best' cooling. The other channel does not have that advantage. Perhaps you might be able to match the channel that shut down to its location on the board?

Maybe it is time to redesign the piece of cardboard. Given that it is 'cheap' make one that goes 'low' over the whole board or appropriate parts, with appropriate cut outs, before collecting the airflow into the fan.

Bonus is people taking pictures on 'loan' units won't 'give the game away'. Plus rather than slating I have provided constructive input.

BbbyBld said:
Because of the design of the amp, this works out if you connect everything as I described a few posts up.

I don't want to describe the reasoning behind this because I don't know if I'm giving away something proprietary.
Click to expand...

It isn't proprietary.

People who 'know' about Class D amplifiers will also know that Half Bridge circuits suffer from something called power supply pumping. In 'simple' terms if your amplifier is delivering a negative voltage/power to the load it also 'pumps' power to the positive rail raising its voltage. That happens the other way around.

If you allow that to happen for too long then, unless there is protection to shut things down, things will go bang. Too long is a design decision and too long affects 'low frequencies'.

One of the 'solutions' is based on an assumption that Bass in a stereo music signal is generally equally distributed between both channels and will largely be in phase. As such if you invert the input to one channel then while it 'pumps' the supply one way the other channel will 'pump' it the other way and they will cancel each other out.

Then you just have to invert the speaker connections to get the correct output phasing. This is going to be why the connections you are being asked to make for this particular amplifier don't 'make', initial, sense.

I don't know PA and other stuff you people are in to but the assumption about a stereo signal might cause you problems if you use one channel for 'subs' and the other for 'highs'. There is a demonstration of ignorance for you.

In terms of playing Bass, and I don't know how low you care to 'throb', the level you play at is going to be part of the sum... To The Max!!?

There has been a post on the AVS forum where someone did some rudimentary bench testing using sin waves and had the amplifier 'trip' or otherwise misbehave down at around 11Hz single channel.

That might not be down to the previously mentioned power supply pumping but could be related to the, excuse my techiness, bootstrap supplies for the main switching devices. Running bridged would probably reduce such concerns both for pumping and bootstrap.

Otherwise, if you are using one of these for Bass then my guess would be that your best bet would be to run it bridged as described to avoid power supply pumping and pay attention to what the other Bloke said about driver ratings.

Blah blah.... blah blah blah blah blah.

It's engineered for a purpose that might cover much of what people need.

Like someone else, if memory serves, mentioned earlier on. Use the thirty day period [?] to make sure it does what you want it to do. I assume Peavy will take it back if it doesn't.
 
#94
Interesting...I have a yet to be released IPR 4500 on order currently. The price listed, even though its not out yet was low enough to make this attractive to me. My plan is to run 2 fEarful 15" cabs off of this for a 'full' rig (each 8 ohms) Figuring I'd run one cab off of each channel. Of course, I guess I could run the amp off of one channel at 4 ohms and have a free channel for other use. OR dependent upon what I find when I get to the show, this could double for PA use.

Any comments, commentary etc. on the best way to use one of these newer higher powered versions of this amp effectively and safely?
 
#95
BurningSkies said:
Interesting...I have a yet to be released IPR 4500 on order currently. The price listed, even though its not out yet was low enough to make this attractive to me. My plan is to run 2 fEarful 15" cabs off of this for a 'full' rig (each 8 ohms) Figuring I'd run one cab off of each channel. Of course, I guess I could run the amp off of one channel at 4 ohms and have a free channel for other use. OR dependent upon what I find when I get to the show, this could double for PA use.

Any comments, commentary etc. on the best way to use one of these newer higher powered versions of this amp effectively and safely?
Click to expand...

I can only comment, unrealistically based on guesses, on the 1600. You might wish to read my comment..... here

Invalid Link Removed

about someone's concerns over damping factor regarding that particular amplifier.

If the IPR 4500 is already bridged internally, the 'manual' will say you can't bridge it, then you won't have problems with power supply pumping so that part will not apply.

In your case, and I'm not the expert [but now you have mentioned it], running two Cabs one per channel, I would guess using the 'pass through', and assuming they are getting the same Bass signal looks Good as far as supply pumping would be concerned and you will achieve the lowest damping.

Without wishing to sound like I am doing FUD I would still be wary about operating these amplifiers as what would be two separate 'mono' amplifiers, one channel for Bass and the other the Harpsichord, without taking other things into consideration....

I don't think they are going to tub themselves as such, the designer who has posted over on AVS seems confident about their robustness, they might just shut up for a while if they are not happy.
 
#96
I'm only running a single channel on mine into a 4ohm cabinet. I've had no issues operating the unit in this manner. I still have not yet run the amp full open, for practice levels if I get the gain up to 10-11 O'clock it starts getting obnoxiously loud. I primarily use Channel A but occasionally I bump to Channel B if I'm trying to A-B a preamp into the power amp and out to a cab. I have no idea what channel is at the back of the board getting the brunt of the fan, or if that board is even laid out back-to-front as suggested above.
 
#97
gastric said:
I'm only running a single channel on mine into a 4ohm cabinet. I've had no issues operating the unit in this manner. I still have not yet run the amp full open, for practice levels if I get the gain up to 10-11 O'clock it starts getting obnoxiously loud. I primarily use Channel A but occasionally I bump to Channel B if I'm trying to A-B a preamp into the power amp and out to a cab. I have no idea what channel is at the back of the board getting the brunt of the fan, or if that board is even laid out back-to-front as suggested above.
Click to expand...

If you look at your pictures then you can see the wiring across to the speakon connectors from the two channels....

peavey_ipr_005.jpg


In that picture

The one/pair to the right are from the amplifier channel 'outside' of the area where the fan/cardboard is located, receiving less cooling, and connect to the Channel B speakon on the rear panel.

The one/pair to the left are from the amplifier channel 'inside' of the area where the fan/cardboard is located, receiving [much] better cooling, and connect to the Channel A speakon on the rear panel.

Otherwise since I don't really 'know' I can't comment on what works or would not work as far as a 'specific' application would be concerned. I know some basics and they suggest that you should check that things do what you want them to do.

That probably applies to any 'similar' amplifier.

Perhaps someone from Peavey can step in and either rubbish me, I don't think they would, or give better figures regarding capability under the scenarios people are considering using these amplifiers for.
 
#98
MortyBoy said:
I can only comment, unrealistically based on guesses, on the 1600. You might wish to read my comment..... here

Invalid Link Removed

about someone's concerns over damping factor regarding that particular amplifier.

If the IPR 4500 is already bridged internally, the 'manual' will say you can't bridge it, then you won't have problems with power supply pumping so that part will not apply.

In your case, and I'm not the expert [but now you have mentioned it], running two Cabs one per channel, I would guess using the 'pass through', and assuming they are getting the same Bass signal looks Good as far as supply pumping would be concerned and you will achieve the lowest damping.

Without wishing to sound like I am doing FUD I would still be wary about operating these amplifiers as what would be two separate 'mono' amplifiers, one channel for Bass and the other the Harpsichord, without taking other things into consideration....

I don't think they are going to tub themselves as such, the designer who has posted over on AVS seems confident about their robustness, they might just shut up for a while if they are not happy.
Click to expand...

Thanks for your input. One of the reasons I chose to order the 4500 is the fact that it should drive my rig fine at either 1 channel at 4ohms or 2 channels at 8ohms each. I'll rule out using the unused 'B' amp as an independent power amp unless I hear from others that it works with a certain level of stability.

The truth is that on some gigs when we're told that the PA can do some heavy lifting we're finding what I would consider practice PA, in which case I'll use the 4500 to run the mains, or the monitors or both as needed and use my LMII for my bass.

A sub 10 pound power amp with this kind of wattage is too good of a proposition at this price NOT to have one in my 'gigbag'.
 

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