agedhorse

How the fan is used, the mechanical design, has in general more impact on the real world noise floor than the fan itself (assuming decent quality fans, and the same air flow + static pressure).

Marketing plays a huge part in the cost of designer fans. 
 

Generally it’s more than the fan that’s responsible for the noise generated. 

A lot of effort (and some expense) goes into making an efficient and quiet cooling system. Cooling is a system, not just a bunch of parts thrown at the problem.

3 hours ago, NHM said:

I did an experiment with my Minmax this afternoon - I unscrewed the fan and took it out, powered up the amp on my desk with the fan running away from the chassis. The same noisy fan was virtually silent, so it is the casing that creates the noise. I need to find a way to make a 'silent' mounting.

Correct, there's a lot more to a quiet cooling system than just the fan, and a lot of ways to inadvertently turn a modified amp into a perpetual paperweight...

On 04/08/2025 at 15:31, basslondon said:

Indeed. Imagine our shock recently when we returned busted Camera boards to  Panasonic UK to be repaired only to find our boards( confirmed by serial number check) contained  fake CAPS in them. Apparently they’d sub contracted out our boards to a third party to service and when they came back the Panasonic caps were not real Panasonic parts…they lasted three months 

This is what starts the urban mythology that caps are "always" the culprit, they always go bad, without digging a little deeper to discover that there are products that last decades without any cap failures. You kind of get what you pay for usually 😉

2 hours ago, basslondon said:

But let’s not forget the “Crap fake capacitor scandal “ a few years ago. Where copy’s of Nichicon and Elna and Rubycon and Panasonic were flooding the market that caused no end of issues…that hasn’t helped consumer confidence 

This is what happens when you buy grossly substandard parts from unauthorized (or non-genuine) supply chains. This is not a capacitor issue, it's a fraud issue.

On 02/08/2025 at 12:14, basslondon said:

 

Yeah in this case i concur that its not necessary but a peek at them to evaluate the state of them would not be completely unwise ( what with it being over 40 years old and of unknown background).

 

In my day job in Broadcast Engineering we are often replacing CAPS on PSU's in ageing broadcast kit in the transmission that remains on for 24/7 ( SDI routers / vision mixers /Camera channels etc and the like) so it would be a formality to check and replace any problematic ones. We have old kit that hasnt been switched off for 10 years that works fine, but wed be very afraid if it powercycled...

Yes, 24/7/365 operation is a little different. I have an amp in my shop undergoing aging testing that’s been in operation like this approaching 150,000 hours (that’s about 17 years). The caps still meet the original design specs. 
 

By comparison, for an audio amp used 4 hours a day, 5 days a week (high usage for a bass amp), that would be about 150 years… so even if the caps lasted half that long we are still talking about 75 year lifespan. 
 

This is quite simplified, but serves to reinforce why replacing caps in amps just because they are a “few” years old borders on the absurd. Or, the design and selection of components is really awful. 

Leave the caps alone, age does not mean that there are problems, or that there will be problems. The whole notion of “must recap” is an absurd extrapolation from a little bit of truth. 

26 minutes ago, djk said:

Bill, according to the Eminence web site these were "Recommended for professional audio and bass guitar applications as a woofer/mid-bass or midrange in vented monitors, satellites and multi-way enclosures."

 

I'm guessing that they were trying to cover all the bases (no pun intended) by implying they could be employed for a wide range of purposes.

 

As a bass guitar driver, it’s very limited. Some of this can be overcome by using multiples of this driver (410 and 810 for example)

On 26/07/2025 at 01:57, Downunderwonder said:

When it comes to the OP, less would be nothing at all.

 

DeOxit has wrecked a lot of gear according to Agedhorse. Less is more is a good maxim.

Indeed, as have any number of brands of "miracle cure-all" sprays. 

There is nothing worse than cleaning up all the additional damage caused by the willy-nilly use of such substances by those who received their electronics education via the internet.

Also, these sprays can damage plastic components, some plastics (including wire insulation) can become very brittle from exposure to this stuff.

Stan Lawrence is a very competent service professional. He may be a little more expensive than an average technician, but I would also suggest that in this case you get (more than) what you pay for.

Those drivers have some SIMILARITIES to the Beta drivers but may in fact have very different performance and tuning parameters. 

This is why it was recommended to take the original cabinet dimensions and cut them in half, splitting the port area (same length) between each new cabinet. This way you don't need to know the driver's parameters and are using the work that Ashdown did when designing the original cabinet.

On 20/07/2025 at 08:58, BassmanPaul said:

I miss Genz Benz who were always so helpful on line, thanks @agedhorse among others. I'm happy that Jeff Genzler is continuing that tradition.

Yes, we both believe being helpful supporting products (and especially when problems arise) is a big part of running a business. It’s part of our culture. 

If this was a language translation issue, that's fine but I was addressing exactly what you wrote even if  that's not what you thought you wrote.

When this kind of thing comes up, and you are using a translation app, recognize that it's possible that your translation is not accurate and when questioned about what you have posted, consider that you could have made the mistake and be respectful in your follow-up responses.

I deal with the international community every day, I am very careful how I write responses and how it's possible that they might be mis-interpreted and rarely encounter disrespectful responses unless there is more to the story that I am unaware of.

Have a good day.

6 minutes ago, Beedster said:

I suggest you work out the answer for yourself while you fix your own amp

Yes, that's always his option as well. 

34 minutes ago, nuno1959 said:

Well my dear sir, before going on & on about it, you could always read what i answered before which addressed all of your concerns about sharing schematics  as in this small bit of crucial info you seemed to have missed entirely such as :

 

1 - You ask "...Even if the information is not yours to share?..."

Obviously you seem to have missed completely when i wrote - "...2nd I would OBVIOUSLY ask them 1st if that's ok with them BEFORE doing it..."  

 

Was there a word i misspelled there to the point you didn't get it ? Sorry, life IS too short to waste yet... here you are.

AGAIN. So.... excuse me if i sound dismissive but really !?

Where i come from respect is NOT owed, it's earned & wasting somebody else's time by asking what was already answered.... well, let's say it's not the best way to do it ?

As far as i'm concerned,  i won't be coming back to answer you over this ridiculous "worry" of yours

Have a great life

I was just responding to YOUR post where you SAID  you would share them... did I misunderstand what you wrote?

8 hours ago, nuno1959 said:

Right.........

 

You are always welcome to disagree with me, but you can probably do so a little more respectfully IMO.

6 hours ago, nuno1959 said:

Thanks for the input even though it brings little to the original purpose of this thread and don't be so shocked :

1st IF Epifani will give me the schematic, it's obviously because they are open for members of their client base to have it, i have been, for some 20 odd years & 3 rigs

2nd I would OBVIOUSLY ask them 1st if that's ok with them BEFORE doing it

Around my circle of friends and family that's how people function, the rest of the world.... 

3rd I doubt they would be so upset about it anyway because as i'm sure you now, a good electrotech can reverse engineer any circuit and make a similar one buying the right components + i'm sure all Epifani's proprietary tech will be patented, etc.... so how hurt will they be if a handful of nerds make their own "Epifani amp"...

4th - And just out of curiosity, have you asked that to Bheringer for example ? Because they are notorious for doing that only in a LARGE INDUSTRIAL SCALE..

So chill a little my man, i'm sure we'll all survive 😉

 

 

You might have a different perspective on this if you have had your designs appropriated from confidential documentation that was passed on to a competitor against your will. I have, it took money out of my pocket and the companies that produced those products.  This may explain our different perspectives.
 

Most modern designs are pretty difficult to reverse engineer without spending considerable effort and cost of doing so. Documentation reduces this cost to do so. Many companies do not release documentation for this reason alone. 

5 hours ago, nuno1959 said:

Will do and if i do get the schematics i'll be more than happy to share them here

 

Even if the information is not yours to share?

3 hours ago, Downunderwonder said:

Isn't that what I said??

 

Sine peak volts X to -X

Square X/X

 

Power twice as much for the square.

 

Sometimes I feel I am losing my mind.

Not quite, unless I read it wrong...

17 hours ago, Downunderwonder said:

If you search for a picture of RMS of a sine wave it will show the RMS point at .707 of the clean peak.

 

The RMS of a pure square wave is the full peak value.

 

Power is Current x Voltage.

Current is Voltage ÷ Resistance.

 

Substituting for Current we see Power is Voltage squared ÷ Resistance.

 

Noting that 0.707 is 1÷ square root of 2,

The power of the square wave is double the RMS power of the clean sine.

 

Trace rating an amp as 250W/500W Peak, maybe a little off the wall as nobody would pay to listen to one putting out the full 500W for more than a few microseconds, could handle mighty transient peaks.

Almost. The power of a square wave is equal to the RMS power of a sine wave and 1/2 the power (.707 x the voltage) of the peak power of a sine wave.  

Peak power is defined for a sine wave at 2x the RMS power, and when Trace advertised 500 watts peak power, that's exactly the same as 250 watts RMS. It has nothing to do with burst power (which has an entirely different definition and applied primarily to broad band signals).

Power RMS is equivalent to the area under the voltage curve x the current curve, and when integrated over time becomes energy. 

On 15/06/2025 at 21:06, Count Bassie said:

The guy who's been repairing my amps the last 6 or so years there me that measuring at 1KHz takes less power than lower frequencies, so the rated power brings a higher number. This is incorrect? 

 

Yes, for the most part that is incorrect. There may be a trivial difference at very low frequencies due to filter cap time recharge constants, but it will be less than 1/2dB at 30Hz on a properly designed amp and often much better.

Note that meters can be inaccurate at very low frequencies, which why special meters are used for broad band audio measurements.

2 hours ago, Count Bassie said:

Power is measured differently than it used to be. The numbers get blown up and it seems like power just ain't what it used to be. It is, it's just sold "differently"... Advertising...

Not necessarily. I'm still measuring the same way today as I did in the 1970's and every product I have designed uses power based on RMS metrics and states THD. For MI applications, especially where the distortion harmonics components may be integrated into the signal in both the preamp and power amp, I have standardized on 10% because after a lot of test player contributed their perceptions, 10% was pretty much the sweet spot where most players liked both the tone and texture. The most common numbers I see for bass amps range from about 5% to 20%, depending on the application. For guitar amps intended to be overdriven as part of their native tone, 10% to 30% is more common. Of course, the amps must be tested and safety certified under these conditions if being honest.

For pro audio, the numbers are different of course, and as powers increase the duty cycle factors into the equation. This is most common at very high powered pro audio amps, where after a second or two, the limiting algorithms fold the power back to about 1/2 the rated power and in big powered speakers, the HPF may shift upwards and the crossover points may also shift along with the limiting thresholds. This was all started with Meyer, Renkus Heinz, Apogee and later with JBL, etc. This has allowed maximum performance with minimum damage and warranty claims.

6 hours ago, BassmanPaul said:

What's the old saying? Nothing ventured, nothing gained!  

or lost...

1 hour ago, Beedster said:

That’s what I meant, we knew we had to be careful. I think lightweight lures us into thinking it’s not so easily damaged 👍

Agreed, a false sense of security