Warning About The Singlepower Extreme - Owners Please Read - Page 4

Ok - a very basic question. I've had my PPX3 Slam for 3 yrs or so. I am the 2nd owner & not sure how long the original owner used the amp. It is completely stock & has never been sent back to SP for upgrades or repairs. It has operated without any problems as long as I've had it. I've often left it on for weekends when I'm using it a few hours at a time - rather than turn it off & on several times. Should I be concerned & do I need to have it checked out? What are the chances that an amp that has operated perfectly for 4 or more years has one of the dangerous flaws being discussed here? I'm probably not alone in being a consumer without much technical knowledge & feeling a little uneasy & confused.

Gound?

"A primary to primary (which is the secondary) short (monoboys amp)
could put a significant percentage (depending on where the short is)
of the AC line onto the chassis. The fuse may or may not blow. And
current will flow from the chassis thru whatever low impedance it
finds to ground/neutral. Likely thru another component like your source."

The ground pin on the AC cord would not directly ground the chasis; rather, current would flow into the source, and from it to ground?

I though the reason for the grounding pin on three prong cords and outlets was to prevent the instance of poor design, or poor luck, so that the the chassis conducted to ground, and not to another electronic or biological component.

You might want to look at some of those pictures where the green wire
from the IEC input block is connected to chassis ground by scraping some
of the paint away from only the inside, usually without a star washer.

And i know that some of you use cheater plugs to get rid of ground loops.

Nurxhunter, it's good to hear that you haven't had a failure and have had good performance from your amps.

When it comes to failure, electronics are not like cars and you don't necessarily get warning signs. Further, there are multiple modes of failure - some much more dangerous than others. If you want to use a car analogy, for example, a bad alternator will drain your battery and eventually leave your car dead.

A bad alternator, however, will not leave your car dangerous to the touch. It is also unlikely to start a fire inside your car. Most of what happens to a car results in it not running. A car that isn't running (with a few exceptions) isn't life threatening. Another important point is that cars are thoroughly inspected by the government, are built to various safety standards and the manufacturers have deep pockets - if they screw up they're liable. There's absolutely nothing like this kind of regulation, oversight and liability when you're building amps in a garage.

An amp that shorts to the chassis is potentially life threatening.

Another thing I want you to keep in mind is that electronics do not improve with age. Every resistor, cap, transformer, diode, switch, and tube has a rated lifespan. You can even look up the manufacturer's lifespan ratings at Digikey and Mouser. Every part inside an amp is due to fail sooner or later.

New components can take more abuse than ones that have been abused. If something has held up to abuse for several years, it will not have an infinite lifespan or anything close to a normal one.

It's easy to think of amps as static and with no wear items besides the tubes. But it's not like that. Everything inside is going to fail sooner or later. What happens during a failure depends on which part goes. There are lots of thing that happen when you subtract a part, which can then lead to the failure of other parts.

I urge you to give your amp a more thorough checking than taking a peek at the transformer and sniffing it. You need to know its rating. You need to know whether it is being run too hard. Since you have a family, do it for their sake. You wouldn't want to leave it on one night and have it start an electrical fire in your house. Like I said, components do not last forever. You can keep rolling the dice, but you know you can't win every round.

Unc,

I respect your opinion and glad to have your experience applied to our problem. What you state has truth to it in abstract so I won't argue with your approach. But what you say can be said for anybody's amp. Are the ZDs certified, RSA, LD, DV? This should be a wake up call for everybody in this hobby to take a closer look at what is sold on these forums. We do not have credible accountability to protect us from this thing happening to any device that has 120/240v plugged to it. The same "death threats" were used to justify why no one should buy from VD. The thrust was motivated by the "perceived" high markups and not by known evidence of failure. For us to have credibility in protecting our members, we have to be neutral in our biases and stick to the facts of the issue.

Thank you Mr. Gilmore for putting your time and considerable knowledge to our problem.

Good points

Wise to check out amps, despite fine function and great sound

Apparently, DIY tube amps have been sold (think Heath, Lafayette, Dynaco) for decades. Surely, dopes on occasion have put these together.

No where can I find warning not to buy old DIY amps. Everywhere I see warnings not to open them if not educated in the craft.

Dr. Kevin mentions the use of cheater to bypass ground. Shouldn't that elicit MUCH more concern? Old news. Audiophile like to live on the edge?

So, my perspective is that the Extreme is likely not a live grenade, a ticking time bomb, or an electrocutioner. It will not likely blow up, or burn down a house. The instances so far--at worst--seem to be a fried transformer (not a surprise in this field at all), and poor craftsmanship (not 'shocking' in this field), maybe even deceit (well, that is interesting; see below).

The risks here are far lower than buying and using an 807-based amp. No one has ever become hysterical over those naked tube-end caps that could be transmitting 500V right into a user, or child, or cat, though that risk is quite real.

If users are checking out the Extreme, they should certainly check out any DIY tube amp. Old news.

The real news is that THE leading vendor of tube headphone amplifiers has scammed some very knowledgeable, even 'supreme' audiophiles, for YEARS.

Now, THAT is shocking.

1/16" Allen Key Hex Key-- Craftsman # 46730

This cost me $2. Works quite well on the SinglePower amplifier Allen Hex Screws.

Make sure it is VERY WELL SEATED in the bolt and apply considerable vertical pressure down into the bolt so the key does not slip and strip the screw, then, you WILL be screwed.

The problem is, I believe, that the thick case applies outwards pressure on the bolt, making the friction too high to turn easily. You might be better off with a touch of WD40 than heat. Heating the bolt will expand the bolt; logically, this could make things worse.

A handled hex key perpendicular to the shaft would be ideal to allow more torque--I could not get this.

Craftsman 946730 has worked well for me in all the SP amps.

After you have your amp checked out, if you are satisfied with the tech you use, please consider posting the relevant information in this thread:

http://www.head-fi.org/forums/f5/sin...thread-437808/

I absolutely don't think te advice to downplay the good sides of this amp is silly. A lot of people only read a few posts. If in those post a item gets the label "good" they might buy it. And in that way you could be indirectly contibuting to their death. Electrocution, burning down the house and explosion hazard are NOT to be taken lightly. In my opinion it overshadows any merrit this product might have.

Along the same lines keeping the amp "as-is" is - if you know of the danger - downright irresponsible.

Car manufacturers (have to) pay for recall of products if anything this dangerous is found - can't SP be forced to do the same?

SP would just file for bankruptcy and without any holdings there is nothing that can be done. Who knows how many amps are out there (hundreds?) which all have to be fixed.

Perhaps if there was an incident to justify it. Car recalls usually occur when the threats happen and people die. The products are not certified, the govt. won't get involved in internet commerce that isn't taxed, the legal route won't involve enough money to make it worthwhile to pursue. The options are limited and minimal. Best to do it the old fashion way, let the community deal with its scum.

Yeah, right, people are that stupid. If someone says: "It's too bad we're having all these problems with these SP amps, because mine really sounds great," that comment will cause others to completely ignore 100 other posts saying the amps are likely to blow up like hand grenades. Give me a break. The problems with these amps are discussed at length on many, many threads, and nobody is going to miss it.

And the suggestion that people who comment on the "good" aspects of these amps might be indirectly contributing to someone's death is downright offensive and completely uncalled for. I request that you remove it.

For crying out loud, nobody is taking it lightly. Every one of these SP threads has the same problem of "political correctness." Any post that doesn't say that Mikhail is the anti-Christ, his amps suck in every conceivable aspect, they're extremely dangerous and death is likely to result from just touching one, etc., is judged as "taking the issue lightly," or something to that effect. This is just absurd.

Moreover, IMO, your type of post actually undermines the seriousness of the safety argument. I have had several people comment to me privately that they don't understand the reason for some of the hyperbole on some of these threads, and they wonder if some folks have some sort of agenda. It's important that the truth about these safety issues not get obscured by hype.

Look, the facts are the facts, and they speak for themselves, and everybody is being made aware of them. And once the facts are made known, everybody is free to evaluate the risks and make their own choice. I'd prefer to make my own choices and not have someone else, who apparently thinks they know better than I do as to what's best for me, tell me what to do with my amp in my house. It's a free country -- at least it is here in the USA.

So let's continue to share the facts, and please keep the judgmental BS and stance of moral superiority to yourself.

P.S. The fact that I started a thread to identify techs and repair shops where people might be able to get their SP amp checked out and repaired shows that I am not taking this issue lightly, and that I don't think others should just ignore the issue.

I cracked open my case tonight after seeing this sobering thread. I seem to have the oddly wired 6.3v filament transformer based upon Kevin's helpful color guide. The rest of the amp looks to be better turned out than the one in Nate's photos. My tube sockets have a small PCB adaptor between the circuit board and the tube sockets, no air wires. Wire dressing looks good although the filament rectifier looks a bit small. Hex headed screws for the chassis.

Two questions.

1. Nate could you post the wire diagram you mentioned. I am having a hard time figuring out how SP got the high voltage in a correct range. In my mind I have one half of the transformer stepping down for 6.3v and the other half wired "backwards" for the HV. It seems to me that the multiplier for the HV would be way high?

2. Kevin. Would the Hammond 378C or 378CX be a drop in replacement or would circuit values also need to change? I have done enough building to replace the TX as a drop-in but I would be uncertain about changing resistor values.

Thanks for the thread and your input. Boy, my Extreme has been on the shelf since buying my Tekton amp and I was getting ready to sell it. Not sure if I could sell it stock in good conscience now. Too bad as it is a great sounding amp and had no issues in two years.

Best,

Paul

That is way to high of a high voltage. An extreme really wants to
be 150 to 180 volts rectified and filtered.

There is an edcor transformer that is cheap that works.
EDCOR - XPWR039

Internal pics of my Extreme taken some time ago





Though the unit looks relatively new (Feb 2007), the transformer is probably the 'WRONG' hammond 266n12 according to Kevin's guide... Correct me if I'm wrong.