Anyone have opinions on this Driver/Amp combo?

Discussion in 'Home Theater Projects' started by drexel, May 4, 2003.

  1. drexel

    drexel Agent

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    Stryke Amp

    Stryke SAE1204

    The driver on that page is the Stryke Audio SAE1204 12" Woofer. I'm not too edumacated when it comes to those technical specs, but can anyone predict the quality that a vented sonotube would have with that woofer/amp combination? Has anyone heard anything about this driver used with sonotubes and larger volume applications?
     
  2. Allen Ross

    Allen Ross Supporting Actor

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    at first it looked like that amp is the same one as the PE. but on the shcematic it is compleatly differnt. i guess that why they are pushing 350 @4 ohms.
     
  3. JimPeitersen

    JimPeitersen Second Unit

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    I've used John's products before, and can say that you will not be disappointed with that particular combination.
    JP
     
  4. Frank Carter

    Frank Carter Screenwriter

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    The sub is good, but you can get the same amp with a variable subsonic filter for $10 cheaperhere.
     
  5. John E Janowitz

    John E Janowitz Second Unit

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    Frank,

    The only problem with the Rythmik is that it still has the 80V caps in the power supply that tend to go bad. Out of about 100 amps I sold with the 80V caps, about 20 of them ended up going bad so far. Not a very good percentage. What happens is that the rail voltage gets right up to 80V and the caps just melt. At first we thought it was only from driving low impedances, or operating at high levels. Then some went bad just under normal usage. Make sure if you buy from them that they'll cover the bad caps. All of our amps have been upgraded to 100V caps now, so there won't be any more issues.

    John
     
  6. Frank Carter

    Frank Carter Screenwriter

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    Thanks John,

    I was going to buy one from them for a sub I'm building for my parents, I don't think I will anymore.

    Frank
     
  7. John E Janowitz

    John E Janowitz Second Unit

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    Hi Frank,

    Not saying you shouldn't buy one. Just see what he says about the warranty and how long he will cover it. I just had 2 this week that I sold over a year ago and they just now went bad. Because it was a defect from the factory, I still covered it even though it was past the warranty period.

    John
     
  8. Brian_DR

    Brian_DR Extra

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    John,

    This is Brian from Rythmik Audio. I don't think it is ethical to attack other's products in public forums without giving all the facts. Especially when none of my customers had this problem so far. Why didn't you publicize this problem when you already knew there was a problem with "your" amps.

    Quality control is my highest priority. I had spent a lot of efforts to QA this amp. There were some resistors working under 4x of they rating. I had asked the manufacture to change the design.

    To assure everyone that I firmly stand behind my products, I will give 3 yrs warranty on this amp (filter caps or not).


    Brian
    Rythmik Audio
     
  9. Paul Stiles

    Paul Stiles Agent

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    Just because a capacitor (in this case aluminum electrolytic ones) is operating at or near it's rated voltage does not mean it will fail prematurely.

    Three examples:

    1) Back in my BSEE school days (mid-1980s) I made a pair of mono-block solid state power amps. Beings I did not have a lot of money to spend, I bought surplus parts when the cost of new ones through retail channels was prohibitive for me. The power transformers, main (output stage) filter caps, and heat sink assemblies were all bought surplus.

    The filter caps (four per mono-block) for the main output supply were rated at 35,000 uF and 75VDC. They are operating at 72VDC nominally. All 8 of them are fine.

    I also have a Hafler XL-600 power amp. The four main filter caps in it are rated at 100VDC and have 95VDC to 100VDC on them, depending on what the AC line voltage is. This amp is from the very late 1980s.

    A friend has the Hafler DH-500, which is an earlier vintage than the XL-600. The two main supply caps, rated for 100VDC, in that amp are running at about the same voltage ad are the ones in my XL-600.

    In all of these amps, the original main supply filter capacitors are functioning properly after at least a decade of use.

    Several factors can cause a capacitor to fail prematurely.

    A capacitor with high e.s.r. (equivalent series resistance) and large ripple currents will warm up and be more likely to fail early, especially if it is in a hot environment. A high dissipation factor will have a similar result.

    If a cap is operating at or near it's rated voltage and the AC line goes up in voltage, then the cap may be operating above its rated voltage. Depending on how much "safety margin" is built/designed into a particular cap, and if other factors, such as high e.s.r., high ripple current and hot environment, come into play, the cap may fail. A cap's rated surge voltage will give some idea of this safety margin.

    In the case of the amps I listed above, I would like to replace the caps with new caps, with higher voltage ratings. In the case of electrolytics, they dry out over the years and the capacitance decreases. My preference for aluminum electrolytics is that I like to have an absolute minimum of 25% safety margin, 50% makes me feel much better, but the cost, already high for these type of caps (and outrageous for the audio jewelry versions) makes me make do with what I presently have until I can find suitable improvements/replacements at a reasonable cost.

    So, just because a cap is operating at or near it's rated voltage does not mean it is going to fail prematurely. A properly selected quality capacitor, even if it is operating at or near it's rated voltage, can function reliably for many years.

    Paul
     
  10. Jon Torres

    Jon Torres Second Unit

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  11. John E Janowitz

    John E Janowitz Second Unit

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    Brian,

    As I said, this was only a WARNING. I never stated not to buy from you. I just said to make sure that this issue would be covered by your warranty. I know of several other companies selling the same basic amplifier. One of which I know was not covering the capacitor issue. They had claimed that anyone who had problems with the capacitors had "abused" the amplifier and caused it to fail.

    Also, it was not publicized that there was a problem because it was not realized at first. I have sold probably around 100 of these amps. Over the first year, I had problems with only one amplifier. Then it seemed like all at once quite a few of them came back. At that point I pretty much stopped selling the amps for a time until we could get enough parts to replace the 80V caps with 100V caps on all the problem amps. The latest batch come with 100V caps, so there is no more problem.

    Brian, I am glad that you stand behind your products. If that is the case, there is no reason for anyone not to buy one of your amps. Again, it was just a suggestion to make sure that your warranty will cover issues with the caps if they come up.

    Paul,
    you are correct that just because the voltage is near the limit, will not make it fail. However, the safety margin on these 80V caps appears to have been fairly low. I have seen many of them where the caps melt and begin to ooze out the top.

    John
     
  12. Brian_DR

    Brian_DR Extra

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    Jon,

    For those who had purchased the amps (serial number C000108 and earlier), the warranty will be extended to 3 yrs.
    I will not sell any more amps with 80V filter caps. All the new ones will come with 100V filter caps and match the best warranty in the market for similar 350W amplifiers. Let me know if this is not reasonable.


    John,

    Comparing features is one thing. Implying someone else's amp will fail is another. When I ordered my batch from the supplier I specifically asked about the filter caps. Their answer was the cap spec has improved along the way and earlier problems should not repeat. I guess for now it does not matter if this is true. Anyway I will put in 100V filter caps for all the amps I sell from now on. Hope this will settle everything.

    Brian
     

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