What amp isn't reliable?

[greenboy]

Jerrold, add to the list (I think) Aged Horse of Genz Benz, and QSC's main man here, Bob Lee. There may have been other posts too, that I missed.

Before reading any of your posts I came at it from another tack: a lot of power amps probably draw when doing performance-levels duty, as much or more than the surge protectors can reliably supply anyway. I had one lender amp for a while that proved this out ; }

 

[The Golden Boy]

Let me try this...

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The panel doesn't extend all the way to the front, however, the open portion is under the tuner in the rack.

 

[The Golden Boy]

No making fun of my awesome "drilling in a straight line" skillz.

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[Stride000]

Here's my experience with some amps i had.

GK 800RB - Never had a technical problem with it but it seemed a bit under powered and the two high and low outputs were inverted.

Eden Traveller 500 - Been pushed hard and never had a problem with it.

Ampeg SVT-4 Pro - First one i tried at the store had one if it's power amps blown. The one i end up bying started having problems within a couple of months. One of the power amps became less powerful and the Bi-amp switch wasn't working anymore.

Aguilar DB750 - Upon the first week of use I had some crackle in the sound probably due to a dirty jack (never been confirmed) and there was i slight electrical hum. The preamp tubes keep going bad at every 4-5 months and the head is rackmounted with foam underneath it to prevent shocks. PLus, it doesn't tour extensively.

All this to say, no matter the price, the build quality and the way you use it, you can always stumble upon a lemon.

 

[skidrawk]

Lightning is another issue altogether. it can actually damage a unit that is not plugged in, although that is more rare. Lightning-damaged units, when really zapped, have weird problems, sections of wire vaporized, and the adjacent ones OK, parts literally exploded, etc.

I agree that the protectors can be good. With a proper fuse, they can be effective.

However, they are not a cure-all, largely due to the fact that they typically will let through a spike of hundreds of volts over the mains voltage. It is inherent in their ratings, which are VERY sloppy as to suppression voltage.

A proper application of transient suppressors is more than soldering in a couple of parts. At least half the "protected" outlet strips sold today will let through transients of over 500V. So much for "protection".

Aside from lightning, for which all bets are off, the transformer etc, DOES hold up against the vast majority of "normal" transients.

I would NOT think of a unit less positively if it did not have a "suppressor", nor would I consider a unit "better" if it DOES have one.

You can always buy a GOOD plug-in protector if you feel the need.

Are problems related to lightning normally covered under warranty?

 

[lbanks]

The only amp I had reliablity problems with was an old Gibson... and it was old. However, I have heard a lot that didn't sound very good.

 

[BassmanPaul]

Greenboy, having taken yet another look at your amp I see several problems. You have an amp that may sound wonderful but it has a poorly designed cooling system. If you want to use it to it's full potential you are going to have to redo the cooling system properly. As Jerrold correctly states, the gap between the heat sinks and vent shouldn't be there. As he says, hot air can get back into the chassis with ease. You need to block the leak. As the heat sink can get really hot whatever you use should be able to take that heat. Probably a piece cut out of a heatproof board from a kitchen supply store would do the job. Obviously you will have to cut holes in it to let the air through.

The other problem I see is that gap between the sinks for each channel - there shouldn't be one. If you equate your amp to your house your duct work is full of gaps. Seal that gap with a length of aluminum tape used to seal duct work.

I have suggested that you reverse the air flow path and doing as I have suggested with an exhoust fan on the rear panel will IMO fix your problem permanently.

 

[The Golden Boy]

Greenboy, having taken yet another look at your amp I see several problems. You have an amp that may sound wonderful but it has a poorly designed cooling system. If you want to use it to it's full potential you are going to have to redo the cooling system properly. As Jerrold correctly states, the gap between the heat sinks and vent shouldn't be there. As he says, hot air can get back into the chassis with ease. You need to block the leak. As the heat sink can get really hot whatever you use should be able to take that heat. Probably a piece cut out of a heatproof board from a kitchen supply store would do the job. Obviously you will have to cut holes in it to let the air through.

The other problem I see is that gap between the sinks for each channel - there shouldn't be one. If you equate your amp to your house your duct work is full of gaps. Seal that gap with a length of aluminum tape used to seal duct work.

I have suggested that you reverse the air flow path and doing as I have suggested with an exhoust fan on the rear panel will IMO fix your problem permanently.

I really don't like the idea of reversing the fan and pushing the heat into the chassis. Regardless if the hot air does dissipate, it's still going to heat up everything in the amp before it exits.

Although I have had the heat sinks apart, I don't really recall, but I believe they are seperate sinks- I believe that gap is supposed to be there.

I'm probably going to drill another row of holes into the rack handle panel if I can get the bit in there.

 

[ergodynebass]

My only amp that has ever went out on me is a Peavey 30w but that was only because I blew the speaker.

 

[Jerrold Tiers]

I really don't like the idea of reversing the fan and pushing the heat into the chassis. Regardless if the hot air does dissipate, it's still going to heat up everything in the amp before it exits.

+1

it will heat up what is already a transformer that will get hotter than another alternate design would (toroid).

Plus, the effect of radically heating other components as the hot air is blown thru the chassis is unlikely to be a good thing. Failures normally go up a factor of several times for each 10 deg C increase in temp.

First on the list of cooked parts would be the fan, if it is directly turned around.

 

[BassmanPaul]

I really don't like the idea of reversing the fan and pushing the heat into the chassis. Regardless if the hot air does dissipate, it's still going to heat up everything in the amp before it exits.

Although I have had the heat sinks apart, I don't really recall, but I believe they are seperate sinks- I believe that gap is supposed to be there.

I'm probably going to drill another row of holes into the rack handle panel if I can get the bit in there.

Just remember {stress mode on} EVERY HOLE YOU DRILL IN THGE CHASSIS WILL JUST MAKE THINGS WORSE! {stess mode off} These are just band aid solutions and will never fix the problem permanently. All you are doing is degrading an already poor cooling system further.
The gap between the heat sinks IS part of the problem You need a tunnel witout leaks for the highest possible transfer of heat. Jerrold does have a point about the fan position, you would need a high quality fan to take the heat which I would hope they have used, However seeing the quality of the existing engineering that is probably wishful thinking!

Options - measure the size of the gap between the side wall and the heatsink assembly. Undo the mounting screws and redrill the holes so that the end of the heatsinks are flush with the side (as Jerrold suggests), Use a spacer as I suggested. Either way - scratch one probematic gap. Tape up the gap between the heatsinks to direct the air flow where you need it. Add the fan to the back panel this time blowing in.

You said that you have had the amp modules out of the chassis. you did make sure that there was no dirt and dust blocking the fins?? The existing fan is actually running?

 

[::::BASSIST::::]

Okay. Now my question is what was wrong with them? What specifically contributed to poor reliability?

When you say "failed" you, do you mean that you plugged it in, turned it on, and then nothing...

What are the poor results some people are having with Ashdown? Is the "poor result" that they just didn't like the product, or did a knobs fall off of it? Did it make a huge fart sound and smoke poured out of the back?

What are these reliability issues?

Joe

The first amp I bought was a behringer bx1200 combo. I bought it brand new for $300 cdn. It died within 6hrs of use. I was playing for an hour or so and then got nothing but a loud 'electrical' noise.

That was it. Luckily, it blew within 30 days of purchase and the shop gave me a full refund with no haggling.

That said, I've had a behringer mixer for 3 years and its seen alot of use and still works fine.

I wouldnt buy another behringer amp. Funny enough, I really liked its tone. Too bad, really.

 

[thatACEduel]

i bought a fender rumble 100 about a year ago
and it sounds great for practices and such
and has a pretty good tone
but any louder than about half way is crackly and it doesn't really have a lot of punch
o and my first amp (25 watt crate) had a LOT of problems
but that was cuz i was trying to play over drums
and i'm pretty sure i blew that out too

 

[Bob Lee (QSC)]

I'm thinking of reversing the fan, and actually blowing fresh air into the rack.

That would help. The way you have it now doesn't help cool the amp much.

Keep in mind that the air flow on the high pressure side of a fan--that is, the air pushed by it--is directional. The air flow on the low-pressure side, though, is diffuse and non-directional; so unless it is ducted to the region of hot air you want to remove, it's much less effective at ventilating a specific space.

 

[Bob Lee (QSC)]

I disagree. "Authorized" repair company is an extension of the manufacturer itself.

No, they're not. "Authorized" service centers are independent businesses that contract with the manufacturer to provide warranty service. The only control the manufacturer has over the service company is that they can sever the contract if the repairer does not do a satisfactory job. If doing the manufacturer's warranty work is reasonably profitable and hassle-free, the service center will usually (not necessarily always) have some incentive to keep the manufacturer's customers happy. Conversely, if the relationship with the manufacturer is not worth the effort it takes, the service center will have little incentive to maintain it. Either way, the manufacturer can't run the business itself.

 

[The Golden Boy]

That would help. The way you have it now doesn't help cool the amp much.

Keep in mind that the air flow on the high pressure side of a fan--that is, the air pushed by it--is directional. The air flow on the low-pressure side, though, is diffuse and non-directional; so unless it is ducted to the region of hot air you want to remove, it's much less effective at ventilating a specific space.

Thank you Bob.

My line of thinking was that the hot air that does leave the chassis rises to the top of the rack case, and in essence "fills" the rack case to the point that the amp is drawing in more hot air than fresh air from outside of the rack case. The fan, in my mind, would remove hot air from the top of the rack case, allowing fresh air to "fill" the rack. Also, because the fan is located in line, above and to the rear of the exhaust grille, my thought was that it would aid in removing hot air close to the source= the exhaust grille.

I should have time this evening to mess with it. If I can get the drill bit into the handle recess I'll drill more holes as well.

 

[The Golden Boy]

Just remember {stress mode on} EVERY HOLE YOU DRILL IN THGE CHASSIS WILL JUST MAKE THINGS WORSE! {stess mode off} These are just band aid solutions and will never fix the problem permanently. All you are doing is degrading an already poor cooling system further.
The gap between the heat sinks IS part of the problem You need a tunnel witout leaks for the highest possible transfer of heat. Jerrold does have a point about the fan position, you would need a high quality fan to take the heat which I would hope they have used, However seeing the quality of the existing engineering that is probably wishful thinking!

Options - measure the size of the gap between the side wall and the heatsink assembly. Undo the mounting screws and redrill the holes so that the end of the heatsinks are flush with the side (as Jerrold suggests), Use a spacer as I suggested. Either way - scratch one probematic gap. Tape up the gap between the heatsinks to direct the air flow where you need it. Add the fan to the back panel this time blowing in.

You said that you have had the amp modules out of the chassis. you did make sure that there was no dirt and dust blocking the fins?? The existing fan is actually running?

There's a lot of things that are part of the problem here.

What I believe first and foremost of all the problems is getting hot air to exit the chassis of the amp in the most efficient manner possible. To my way of thinking, hopefully the combination of the holes in the rack wall and the fan pushing air into the rack will alleviate the problems.

As far as the top panel- I understand that in the perfect scenario, the airflow system shouldn't be messed with- if it's working. However, as it's implemented it's not working. The holes in the top panel are providing some measure of ventilation to the interior of the chassis that currently isn't.

The fan is indeed working and there's no excessive dust on the heat sink. (the heat sink needed to be removed to replace a damaged cap that was damaged when the amp overheated 6 months ago.)

 

[BassmanPaul]

There's a lot of things that are part of the problem here.

What I believe first and foremost of all the problems is getting hot air to exit the chassis of the amp in the most efficient manner possible. To my way of thinking, hopefully the combination of the holes in the rack wall and the fan pushing air into the rack will alleviate the problems.

As far as the top panel- I understand that in the perfect scenario, the airflow system shouldn't be messed with- if it's working. However, as it's implemented it's not working. The holes in the top panel are providing some measure of ventilation to the interior of the chassis that currently isn't.

The fan is indeed working and there's no excessive dust on the heat sink. (the heat sink needed to be removed to replace a damaged cap that was damaged when the amp overheated 6 months ago.)

Every thing you are suggesting here are band-aid solutions that will never cure your overheating problem. Yes, in a perfect world you would not have had to go through any of this, however this is not a perfect world. You are stuck with a good unit that is crippled by a badly designed cooling system. Trying to get this system to work by doing what you are continuing to describe is never going to work in a million years. You have to redo said cooling system (surgery) to cure what is ailing it.

I have tried here to give you the benefit of heading on for fifty years of building, designing, modifying and repairing amplifiers both tube and solid state. I can SEE what your problem is, as can many others on this site, but I seem to be failing to pass that information on to you in such a way that would make an impression on you. For that I am truly sorry and it is exasperating me. If I could get my hands on your amplifier, this problem would be rectified to your satisfaction within about 30 minutes. You can try the cure that I have already suggested, it is very easy to do, and undo for that matter if I am talking through my rear end, or you can carry on drilling useless holes to your hearts content.

Good luck my friend...
Paul

 

[RandallFlagg]

Well, considering that the SVT4Pro I use "tends" to get a little warm...I ventured forth unto my local Wally World and plunked down $9.00 American and bought a "clip-on" fan that blows directly into my rack (especially the 4Pro)....haven't had a problem with "gettin hot" since then.....seems like a fairly simple solution to a non-complex problem....

 

[RAM]

Two experiences of mine, neither embellished, just for the sake of comparison of reliability.

1. In the early 1980s I owned a Peavey TKO65. I HATED the tone of that thing, it was just horribly honky. But, it never failed on me. One time, in fact, I was so ticked off at the tone I actually picked it up and threw it several feet. It still turned on and produced a sound, unaffected by its flight. In fact, the only damage from this was a minor scratch to the vinyl cover.

2. In the early 2000s I owned an EBS Fafner and EBS 4x10. At the time I wasn't in a band, so this amp never saw daylight, serving only as my practice amp (I bought it with the expectation I'd join a band). Over the next 3 years it was in the service shop 4 times for the same problem: a failing power switch. Mott (EBS designer of the Fafner) admitted to me there was a known problem with the design of the power switch in the first (or second) release of the Fafner. Clearly this amp was not abused in any way, and certainly didn't suffer from overuse or extensive road wear.