Printer Friendly Forum Posts - dead amp, need new recommendations

well, it is a sad day for me. i awoke yesterday morning to the sound of silence in my truck and the smell of the rotting corpse that was my alpine PDX-F4. it passed on suddenly and without warning, no cause of death has been determined.

so, i need a new amp now, from my calculations i will need around a 800W 4 channel in order to give me 100W per channel at 4 ohms and 50W at 8 ohms. two channels will be on my mids and the other two channels will be on my tweeters so that is why the ohm load is different on those channels.

my alpine was the cleanest amp i could buy for the price range of about $350. im looking to stay in that price range but i know that is a tall order to find an amp that is very clean and has that much power so i know i will most likely be spending more than i really want to spend.

i have 4 gauge wire already ran so i would like to not have to re run my wire. any input or suggestions are welcomed and thanks in advance.

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Wow, what killed the Alpine? They are not happy with low impedance loads... does this mean you're not open to replacing it with something like the MRX-F65?

$350 for a 4X100 watt amp limits your choices quite a bit. I haven't used one but you might check out the new PPI Ion series for low-cost and decent power...

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i didnt know they made another PDX-like amp. power wise its actually a little better than my F4. they dont tell you the difference between these amps though which worries me they they compare it too much to a PDX yet its still much cheaper. there must be something they are hiding because i believe you get what you pay for.

i have no idea what killed my apline. it ran perfectly fine for a year and a half just long enough for me to be totally without warranty. the only thing i can maybe think of is that i had a 4 ohm and an 8 ohm speaker per each set of channels, as in channel 1 was a 4 ohm mid and channel 2 was an 8 ohm tweeter. i did it like that so that each gain would control one whole side. it didnt seem to mind this setup at all though. it didnt die while playing, it dies upon turning it on.

none of my speakers were blown, that would have been an even bigger tragedy because i definitely cant replace them.

i might open the amp up for fun just to see what happened because something is definitely physically burned inside, possibly a blown cap.

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in comparison, the PDX is still a much cleaner amp, if anything id buy another PDX because the increase in distortion is not worth the $100 bucks i would save. i would like to stay in the "hundreths" area on the distortion because it wouldnt do my components any justice to hook them to a distorted signal. im probably just sounding picky but my system has a reputation to uphold.

still, ill investigate the PPI ion amps because i actually sell them, ill have to get on the phone with PPI tomorrow and get them to email me a spec sheet because the brochure really doesnt tell you much except their power output. i know they are new for this year too so there wont be any review up yet either.

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Hey SS, I just picked up JL Audio HD1200/1 and HD600/4. I think i paid $400 cash for the HD600/4 from my guy. Cant be beat for the power and price. Im doing the same as you, gonna run the JL Audio Evo 6.5 for the front 1&2 ch for the highs and 3&4 ch for the mids. I will only us about 60watts per channel so it should sound very very clean.

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The best tool in my work shop, is my BRAIN!!!!

im a fan of JL's old slash amps but i have no experience with any of their new amps. as always im sure they are overpriced for what they are.

i cant get JL as a dealer either so ill either have to buy one on the internet or pay full price from my competition. i just looked up some specs and it isnt as clean as my dead alpine and even on ebay its about $150 more.

on a side note, what will you be using as a crossover for your mids and tweets?

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soundnsecurity wrote:

in comparison, the PDX is still a much cleaner amp, if anything id buy another PDX because the increase in distortion is not worth the $100 bucks i would save. i would like to stay in the "hundreths" area on the distortion because it wouldnt do my components any justice to hook them to a distorted signal. im probably just sounding picky but my system has a reputation to uphold.

i take it back, both PDX and MRX are in the hundreths THD category at their rated output but the PDX claims to be in the thousanths in the upper frequency range whereas the MRX doesnt make that claim.

to say that the MRX isnt a clean amp was wrong but i think the PDX would still sound much cleaner. the signal to noise ratio is also a good bit higher in the PDX amps.

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Yea, the MRX series are the new low-cost alternative to the PDX line. They apparently use the same output devices but have cheaper power supplies. I listened to them side by side and I couldn't tell any difference...

If you do check out the Ion let me know what you think. If it's half-way decent it could be a go-to answer for lower-cost installations.

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yea ill definitely check out the ion amps even if its not for me personally if they are half way decent then ill end up with some on my shelf. i would imagine they are similar to the soudstream stealth amps with the addition of the class D design.

ive been looking for ideas all day and so far the only amp i could find in my price range was a Cadence D100.4. i considered a diamond amp but they dont list their full specs, even though i know they are clean i still like to see numbers because i have been very surprised a few times today. a lot of amps that you would think are very clean and are priced accordingly will still have close to 1% distortion.

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the THD for the HD600/4 is THD+N @ Rated Power <0.03% @ 4 Ω per Ch. @ 150watts...... that is much better than the alpine.... what other brands are you a dealer for. Your price should be half the retail for most of the gear???? Love to get my hands on Audison or Zapco amps :)

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The best tool in my work shop, is my BRAIN!!!!

true it is lower i dont know what made me think that i saw .07%. the probem with the JL is that im working with a pretty tight power range since im not using any passive crossovers on my components. i need enough power for my mids which seems to be around 100W but not enough power to blow my tweeters so 50W is a good number. mids are 4 ohm and tweeters are 8 ohms so they use half of the power of the mids. this is where i feel safe with these speakers. i think having the extra wattage from a 150 x 4 amp could be too much.

i am cautious mainly because i cant replace these speakers and also because i am using a very low crossover point on my tweeters and that already makes them more susceptible to damage.

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What's the tweeter?

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well when it rains it pours, hails to be exact, huge hail storm past over my house last night showering my truck with golf ball sized hail. need a new hood and roof thats for sure.

tweeter and mid are both diamond audio HEX Pro(old D9) series components. the mid wants 150 and the tweeter is rated for half of that but what im not sure of is the factory crossover point because they dont really give me the frequency range specs of the tweeter.

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Well, I recommend using the passive crossovers supplied by Diamond as they include Zobel networks and level matching resisters; they are not just straight crossovers they are customized for those drivers. If I recall correctly I think they cross the 2-way set at 4000Hz.

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honestly if i had the space to put them somewhere i would use them but each crossover is only slightly smaller than the alpine PDX i had. they even look like amps too. if their crossover point is set at 4000Hz then im way too low, i have mine set at 2000Hz, the way i came to that number is by listening to them as i turned the crossover point down, arouns 2000Hz is where they really started to sound good. anything higher sounded incomplete. as of now they dont struggle to handle the lower frequencies but i am well aware of the dangers. i think they rated the tweeters low frequency response limit was around 1500Hz.

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No place to put them? An installer can ALWAYS find a place! posted_image

Under the dash? Under a seat? In the glove box? In the center console? I think you'd really be better off by finding a way.

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funny, i guess i can possibly find a spot for them, id definitely have to split them up and put them in different spots. strange how you read all the time that going to a full active setup is better and then when you finally do it now im advised to go back. i might do it some day but for now i like playing with my settings too much to stick with the passive crossovers if i dont have to.

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Well, I'm not one of those who advocates for a full-active setup. You get better overall system efficiency and IMO better sound using a properly designed passive Xover network. But then again, I am biased since I used to make a living designing them. posted_image

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so, i installed a Crossfire BMF600.4 today because i just couldnt take it anymore. i realized very quickly that this is a pretty nice amp. its hard to tell the difference between the crossfire and the alpine as far as quality and sound are concerned. there IS a difference but i cant quite put my finger on what it is. the difference might be just from the switch from a class D amp to an old fashioned class A/B

one thing i did notice was the increase in raw power, the mids vibrate my doors much more than the alpine did even though they are supposed to be close in power. the crossfire is rated at 75 watts X 4 at 4 ohms and that is the 12v rating. at 14.4 volts it should give around 100 watts. i adjusted the gain half way and its louder than the alpine with the max volume being achieved at a few volume notches below where i would turn the system up to with the alpine.

they dont print the distortion measurements on these amps for some reason and i cant get a straight answer from them yet directly but i can say that the sound quality is there. with the alpine i felt that the high frequencies were being over amplified and with this crossfire amp the sound is a little more balanced. maybe the dampening factor on the crossfire is better but i dont think ill ever know for sure. i can say this though, the distortion rating for the lower model crossfire 4 channels is .08% so i would expect this amp to be a little better considering its almost three times the price.

the one problem i can say is that the amp is much bigger than the PDX amp, i had a hard time getting it under my seat where my wires were already ran.

i think ill open the PDX and see if i can fix what is wrong with it. from the smell of things i think it could be an exploded capacitor inside so maybe an easy fix and ill run my rear speakers on it.

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DYohn] wrote:

Well, I'm not one of those who advocates for a full-active setup. You get better overall system efficiency and IMO better sound using a properly designed passive Xover network. But then again, I am biased since I used to make a living designing them.

so is there any particular reason why you would prefer a passive VS an active crossover? ive always read and understood it to be better to filter the signal than the actual speaker. this way you dont have to worry about special interactions between the speaker and the crossover. although a well designed crossover will minimize these effects or take advantage of them to make the speaker sound better.

not only that but you are limited to the set crossover point.

i understand that these particular crossovers are built to be awesome and probably the most elaborate crossovers ive ever seen but im talking about any typical situation.

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A mains crossover only needs to be set to one frequency, the frequency that is optimized for the woofer and tweeter that you are using. As far as "interactions between the speaker and crossover," I'm not sure what you're getting at but "interaction" is how they work.

In general the reasons why I prefer a properly designed passive includes reducing system complexity ( only one amp per channel and less wiring required) much better system integration (meaning the Xover is designed to work with the speakers taking into account their FR and impedance curves), better system voicing (a Xover includes the proper padding, impedance leveling (zobel) and EQ (filters) that might be required by the specific characteristics of the drivers. Setting up an active system you are not likely to know or be able to measure all of this) and lastly a proper passive Xover increases system efficiency and protects the tweeter from over power.

As a system designer I can tell you designing a passive Xover can take many days of testing and they are often the most expensive part of a system. Some crossovers cost twice or three times what the drivers cost. The Xover is the heart of a system and is really what determines how it sounds.

So that's why. :)

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well i guess i cant really argue with that, although i find passives to be more complicated as an installer because you need to find a location for the crossovers(mine is an extreme case) whereas a passive is easier to install in the signal path. you usually end up putting passive's in the doors somewhere because there is little room for anything in the kick panels or under the dash for a nice quality crossover.

the special interactions are exactly the ones you have mentioned, leveling out an impedance curve or filtering the frequencies above or below the resonant frequency so that the speakers play together in harmony.

but, my assumption is that these variables are known. lets say we have two of the same systems with one being active and the other using passive crossovers, both set at the same frequency, do you think the passive crossovers would still make a big difference over the active crossover?

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this is the reason why i dont use my passive crossovers, the other crossover is a regular diamond HEX crossover and its pretty big by most standards, the HEX PRO is like a small amp.

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ok so i took apart my alpine and i want to know if this is fixable:

posted_image

the board is burnt on the top and bottom in the same spot. i dont know what side started burning first but the bottom looks like it got the worst of it with those two chips being almost completely burned.

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I hear IAAI furiously pouring through his manuals to find those schematics, even as I type this... posted_image

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

I say again, not using those crossovers because they are large is like not installing a subwoofer because it requires an enclosure. I highly recommend finding a way and I bet the system sounds better...

As far as repairing the amp, while I'm sure it is possible I'd answer the question "why did those ICs fry?" before I spent any time or money on it.

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yea ive already asked myself that question and i have no idea. i dont know enough to even begin to think about what these parts even do. they seem to be part of the power supply side of the amp but that is just a guess based on their location.

i guess ill have to consider finding a spot for the crossovers since they are bi-amp compatible i really wont have to rewire anything, ill just install them in between the speakers and amp and turn the filters on my active crossover off. i wont un-install it until im happy with the passives. i have to run new speaker wires anyway because i had to extend them when i replaced the amp and i dont like having them extended with lower quality wire than what i had.

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