I.

Recently spotted on Tumblr:

“This is going to be an unpopular opinion but I see stuff about ppl not wanting to reblog ferguson things and awareness around the world because they do not want negativity in their life plus it will cause them to have anxiety. They come to tumblr to escape n feel happy which think is a load of bull. There r literally ppl dying who live with the fear of going outside their homes to be shot and u cant post a fucking picture because it makes u a little upset?”

“Can yall maybe take some time away from reblogging fandom or humor crap and read up and reblog pakistan because the privilege you have of a safe bubble is not one shared by others?”

Ignore the questionable stylistic choices and there’s an important point here worth considering. Something like “Yes, the feeling of constantly being outraged and mired in the latest controversy is unpleasant. And yes, it would be nice to get to avoid it and spend time with your family and look at kitten pics or something. But when the controversy is about people being murdered in cold blood, or living in fear, or something like that – then it’s your duty as a decent human being to care. In the best case scenario you’ll discharge that duty by organizing widespread protests or something – but the you can do is reblog a couple of slogans.”

I think Cliff Pervocracy is trying to say something similar in this post. Key excerpt:

When you’ve grown up with messages that you’re incompetent to make your own decisions, that you don’t deserve any of the things you have, and that you’ll never be good enough, the [conservative] fantasy of rugged individualism starts looking pretty damn good.

Intellectually, I think my current political milieu of feminism/progressivism/social justice is more correct, far better for the world in general, and more helpful to me since I don’t actually live in a perfectly isolated cabin.

But god, it’s uncomfortable. It’s intentionally uncomfortable—it’s all about getting angry at injustice and questioning the rightness of your own actions and being sad so many people still live such painful lives. Instead of looking at your cabin and declaring “I shall name it…CLIFFORDSON MANOR,” you need to look at your cabin and recognize that a long series of brutal injustices are responsible for the fact that you have a white-collar job that lets you buy a big useless house in the woods while the original owners of the land have been murdered or forced off it.

And you’re never good enough. You can be good—certainly you get major points for charity and activism and fighting the good fight—but not good enough. No matter what you do, you’re still participating in plenty of corrupt systems that enforce oppression. Short of bringing about a total revolution of everything, your work will never be done, you’ll never be good enough.

Once again, to be clear, I don’t think this is wrong. I just think it’s a bummer.

I don’t know of a solution to this. (Bummer again.) I don’t think progressivism can ever compete with the cozy self-satisfaction of the cabin fantasy. I don’t think it should. Change is necessary in the world, people don’t change if they’re totally happy and comfortable, therefore discomfort is necessary.

I’d like to make what I hope is a friendly amendment to Cliff’s post. He thinks he’s talking about progressivism versus conservativism, but he isn’t. A conservative happy with his little cabin and occasional hunting excursions, and a progressive happy with her little SoHo flat and occasional poetry slams, are psychologically pretty similar. So are a liberal who abandons a cushy life to work as a community organizer in the inner city and fight poverty, and a conservative who abandons a cushy life to serve as an infantryman in Afghanistan to fight terrorism. The distinction Cliff is trying to get at here isn’t left-right. It’s activist versus passivist.

As part of a movement recently deemed postpolitical, I have to admit I fall more on the passivist side of the spectrum – at least this particular conception of it. I talk about politics when they interest me or when I enjoy doing so, and I feel an obligation not to actively make things worse. But I don’t feel like I need to talk nonstop about whatever the designated Issue is until it distresses me and my readers both.

I’ve heard people give lots of reasons for not wanting to get into politics. For some, hearing about all the evils of the world makes them want to curl into a ball and cry for hours. Still others feel deep personal guilt about anything they hear – an almost psychotic belief that if people are being hurt anywhere in the world, it’s their fault for not preventing it. A few are chronically uncertain about which side to take and worried that anything they do will cause more harm than good. A couple have traumatic experiences that make them leery of affiliating with a particular side – did you know the prosecutor in the Ferguson case was the son of a police officer who was killed by a black suspect? And still others are perfectly innocent and just want to reblog kitten pictures.

Pervocracy admits this, and puts it better than I do:

But god, it’s uncomfortable. It’s intentionally uncomfortable—it’s all about getting angry at injustice and questioning the rightness of your own actions and being sad so many people still live such painful lives. Instead of looking at your cabin and declaring “I shall name it…CLIFFORDSON MANOR,” you need to look at your cabin and recognize that a long series of brutal injustices are responsible for the fact that you have a white-collar job that lets you buy a big useless house in the woods while the original owners of the land have been murdered or forced off it. And you’re never good enough. You can be good—certainly you get major points for charity and activism and fighting the good fight—but not good enough. No matter what you do, you’re still participating in plenty of corrupt systems that enforce oppression. Short of bringing about a total revolution of everything, your work will never be done, you’ll never be good enough.

That seems about right. Pervocracy ends up with discomfort, and I’m in about the same place. But other, less stable people end up with self-loathing. Still other people go further than that, into Calvinist-style “perhaps I am a despicable worm unworthy of existence”. moteinthedark’s reply to Pervocracy gives me the impression that she struggles with this sometime. For these people, abstaining from politics is the only coping tool they have.

But the counterargument is that you’ve got a lot of chutzpah playing that card when people in Peshawar or Ferguson or Iraq don’t have access to this coping tool. You can’t just bring in a doctor’s note and say “As per my psychiatrist, I have a mental health issue and am excused from experiencing concern for the less fortunate.”

One option is to deny the obligation. I am super sympathetic to this one. The cost of my existence on the poor and suffering of the world is zero. In fact, it’s probably positive. My economic activity consists mostly of treating patients, buying products, and paying taxes. The first treats the poor’s illnesses, the second creates jobs, and the third pays for government assistance programs. Exactly what am I supposed to be apologizing for here? I may benefit from the genocide of the Indians in that I live on land that was formerly Indian-occupied. But I also benefit from the asteroid that killed the dinosaurs, in that I live on land that was formerly dinosaur-occupied. I don’t feel like I’m complicit in the asteroid strike; why should I feel complicit in the genocide?

I have no objection to people who say this. The problem with it isn’t philosophical, it’s emotional. For it won’t be enough. The old saying goes “you can’t reason yourself out of something you didn’t reason yourself into to begin with”, and the idea that secure and prosperous people need to “give something back” is a lot older than accusations of “being complicit in structures of oppression”. It’s probably older than the Bible. People feel a deep-seated need to show that they understand how lucky they are and help those less fortunate than themselves.

So what do we do with the argument that we are morally obligated to be political activists, possibly by reblogging everything about Ferguson that crosses our news feed?

II.

We ask:

Pervocracy says that “short of bringing about a total revolution of everything, your work will never be done, you’ll never be good enough.” But he is overly optimistic. Has your total revolution of everything eliminated ischaemic heart disease? Cured malaria? Kept elderly people out of nursing homes? No? Then you haven’t discharged your infinite debt yet!

Being a perfect person doesn’t just mean participating in every hashtag campaign you hear about. It means spending all your time at soup kitchens, becoming vegan, donating everything you have to charity, calling your grandmother up every week, and marrying Third World refugees who need visas rather than your one true love.

And not all of these things are equally important.

Five million people participated in the #BlackLivesMatter Twitter campaign. Suppose that solely as a result of this campaign, no currently-serving police officer ever harms an unarmed black person ever again. That’s 100 lives saved per year times let’s say twenty years left in the average officer’s career, for a total of 2000 lives saved, or 1/2500th of a life saved per campaign participant. By coincidence, 1/2500th of a life saved happens to be what you get when you donate $1 to the Against Malaria Foundation. The round-trip bus fare people used to make it to their #BlackLivesMatter protests could have saved ten times as many black lives as the protests themselves, .

The moral of the story is that if you feel an obligation to give back to the world, participating in activist politics is one of the worst possible ways to do it. Giving even a tiny amount of money to charity is hundreds or even thousands of times more effective than almost any political action you can take. Even if you’re absolutely convinced a certain political issue is the most important thing in the world, you’ll effect more change by donating money to nonprofits lobbying about it than you will be reblogging anything.

There is that politics would even of an unbiased person trying to “break out of their bubble of privilege” or “help people who are afraid of going outside of their house”. Anybody saying that people who want to do good need to spread their political cause is about as credible as a televangelist saying that people who want to do good need to give them money to buy a new headquarters. It’s possible that televangelists having beautiful headquarters might be better than them having hideous headquarters, but it’s not the first thing a reasonable person trying to improve the world would think of.

Nobody cares about charity. Everybody cares about politics, especially race and gender. Just as televangelists who are obsessed with moving to a sweeter pad may come to think that donating to their building fund is the one true test of a decent human being, so our universal obsession with politics, race, and gender incites people to make convincing arguments that taking and spreading the right position on those issues is the one true test of a decent human being.

So now we have an angle of attack against our original question. “Am I a bad person for not caring more about politics?” Well, every other way of doing good, especially charity, is more important than politics. So this question is strictly superseded by “Am I a bad person for not engaging in every other way of doing good, especially charity?” And then once we answer that, we can ask “Also, however much sin I have for not engaging in charity, should we add another mass of sin, about 1% as large, for my additional failure to engage in politics?”

And Cliff Pervocracy’s concern of “Even if I do a lot of politics, am I still a bad person for not doing the politics?” is superseded by “Even if I give a lot of charity, am I a bad person for not doing the charity? And then a bad person in an additional way, about 1% as large, for not doing all the politics as well?”

There’s no good answer to this question. If you want to feel anxiety and self-loathing for not giving 100% of your income, minus living expenses, to charity, then no one can stop you.

I, on the other hand, would prefer to call that “not being perfect”. I would prefer to say that if you feel like you will live in anxiety and self-loathing until you have given a certain amount of money to charity, you should make that certain amount ten percent.

Why ten percent?

It’s ten percent because that’s the standard decreed by Giving What We Can and the effective altruist community. Why should we believe their standard? I think we should believe it because if we reject it in favor of “No, you are a bad person unless you give of it,” then everyone will just sit around feeling very guilty and doing nothing. But if we very clearly say “You have discharged your moral duty if you give ten percent or more,” then many people will give ten percent or more. The most important thing is having a Schelling point, and ten percent is nice, round, divinely ordained, and – crucially – the Schelling point upon which we have already settled. It is an Schelling point. If you give ten percent, you can have your name on a nice list and get access to a secret forum on the Giving What We Can site which is actually pretty boring.

It’s ten percent because definitions were made for Man, not Man for definitions, and if we define “good person” in a way such that everyone is sitting around miserable because they can’t reach an unobtainable standard, we are stupid definition-makers. If we are smart definition-makers, we will define it in whichever way which makes it the most effective tool to convince people to give at least that much.

Finally, it’s ten percent because if you believe in something like universalizability as a foundation for morality, a world in which everybody gives ten percent of their income to charity is a world where about seven trillion dollars go to charity a year. Solving global poverty forever is estimated to cost about $100 billion a year for the couple-decade length of the project. That’s of the money that would suddenly become available. If charity got seven trillion dollars a year, would give us enough to solve global poverty, eliminate all treatable diseases, fund research into the untreatable ones for approximately the next forever, educate anybody who needs educating, feed anybody who needs feeding, fund an unparalleled renaissance in the arts, permamently save every rainforest in the world, and have enough left over to launch five or six different manned missions to Mars. That would be the . Goodness only knows what would happen in Year 2.

(by contrast, if everybody in the world retweeted the latest hashtag campaign, Twitter would break.)

Charity is in some sense the perfect unincentivized action. If you think the most important thing to do is to cure malaria, then a charitable donation is deliberately throwing the power of your brain and muscle behind the cause of curing malaria. If, as I’ve argued, the reason we can’t solve world poverty and disease and so on is the capture of our financial resources by the undirected dance of incentives, then what better way to fight back than by saying “Thanks but no thanks, I’m taking this abstract representation of my resources and using it how I think it should most be used”?

If you give 10% per year, you have done your part in making that world a reality. You can honestly say “Well, it’s not my fault that everyone is still dragging their feet.”

III.

Once the level is fixed at ten percent, we get a better idea how to answer the original question: “If I want to be a good person who gives back to the community, but I am triggered by politics, what do I do?” You do good in a way that doesn’t trigger you. Another good thing about having less than 100% obligation is that it gives you the opportunity to budget and trade-off. If you make $30,000 and you accept 10% as a good standard you want to live up to, you can either donate $3000 to charity, or participate in political protests until your number of lives or dollars or DALYs saved is equivalent to that.

Nobody is perfect. This gives us license not to be perfect either. Instead of aiming for an impossible goal, falling short, and not doing anything at all, we set an arbitrary but achievable goal designed to encourage the most people to do as much as possible. That goal is ten percent.

Everything is commensurable. This gives us license to determine exactly how we fulfill that ten percent goal. Some people are triggered and terrified by politics. Other people are too sick to volunteer. Still others are poor and cannot give very much money. But money is a constant reminder that everything goes into the same pot, and that you can fulfill obligations in multiple equivalent ways. Some people will not be able to give ten percent of their income without excessive misery, but I bet thinking about their contribution in terms of a fungible good will help them decide how much volunteering or activism they need to reach the equivalent.

Cliff Pervocracy says “Your work will never be done, you’ll never be good enough.” This seems like a recipe for – at best – undirected misery, stewing in self-loathing, and total defenselessness against the first parasitic meme to come along and tell them to engage in the latest conflict or else they’re trash. At worst, it autocatalyzes an opposition of egoists who laugh at the idea of helping others.

On the other hand, Jesus says “Take my yoke upon you…and you will find rest for your souls. For my yoke is easy and my burden is light.” This seems like a recipe for getting people to say “Okay, I’ll take your yoke upon me! Thanks for the offer!”

Persian poet Omar Khayyam, considering the conflict between the strict laws of Islam and his own desire to enjoy life, settles upon the following rule:

Heed not the Sunna, nor the law divine;
If to the poor their portion you assign,
And never injure one, nor yet abuse,
I guarantee you heaven, as well as wine!

I’m not saying that donating 10% of your money to charity makes you a great person who is therefore freed of every other moral obligation. I’m not saying that anyone who chooses not to do it is therefore a bad person. I’m just saying that if you feel a need to discharge some feeling of a moral demand upon you to help others, and you want to do it intelligently, it beats most of the alternatives.

This month is the membership drive for Giving What We Can, the organization of people who have promised to give 10% of their earnings to charity. I am a member. Ozy is an aspiring member who plans to join once they are making a salary. Many of the commenters here are members – I recognize for example Taymon Beal’s name on their list. Some well-known moral philosophers like Peter Singer and Derek Parfit are members. Seven hundred other people are also members.

I would recommend giving them a look.

 Elliott Sound Products
Project 114 

BP4078 Class-D Audio Power Amplifier

© December 2005, Rod Elliott (ESP)

These modules were available directly from ColdAmp, but the website no longer exists
Introduction

The ColdAmp Class-D power amp modules are discussed in the PWM Amplifiers article, but this project description shows specific details of the modules and how to use them in real life.  Because of the design, they are much easier to use than many competing modules, and for the simplest application need nothing more than a power supply, and input and output connections.

There are many other options, including …

• Balanced input capability
• Volume control connections
• External low voltage supplies for lower dissipation
• Clipping indicator
• Thermal monitor (thermistor)
• Synchronisation of two (or more) amplifiers
• Comprehensive protection circuits *

The data sheet and application notes are very comprehensive, so armed with these, you will have no difficulty building a complete system using the modules.  The project here is essentially just an introduction to the modules, showing a stereo amplifier that I built using prototype units, and giving the basic idea for a high powered subwoofer amplifier.

Although they are easier to use than many of the other Class-D amps, the ColdAmp modules sacrifice nothing in terms of sound quality.  Distortion, noise and frequency response are all excellent, and listening tests have revealed nothing that you would not expect to hear from any high fidelity amplifier.

Description

The first application has to be a stereo power amp, since that’s what I built using two prototype modules.  The reasons for this choice are twofold … a good high powered stereo amp is always useful, and it was important to be able to assess the sound quality in this role.  I am at something of a disadvantage in this, because the only full range speakers I have are bookshelf units.  They are quite good, but obviously don’t have deep bass capability and suffer the normal limitations of most bookshelf designs.

I have long been of the opinion that bookshelf speakers are so called because one merely has to add a plank of wood to make a convenient bookshelf.  The speakers are best
left disconnected. 

Having said that, the units I have sound very good with the ColdAmp modules – there is no discernible difference between the Class-D amps and a ‘GainClone’ amp (at levels within the range of the GainClone, of course).  It must be admitted that the resolution of the speakers used is not as good as I would prefer, but at present I don’t have anything else available (my main system is tri-amped, and therefore very limiting for amplifier evaluation).

The simplest possible connection requires only a power supply, plus input and output connections.  While there are many other functions, most will never be needed for a home audio system – especially at lower supply voltages.  Heat is not a problem – the amps get slightly warm with no load because of the on-board regulators, and only very slightly warmer in use at normal listening levels.  This is with ±60V supplies (±56V nominal, since I used a pair of 40V transformers).  Remember that the supply voltage will be higher than expected at no load, and lower than expected at full load.

Figure 1 – Front View of Completed Amplifier

The front view is shown above.  The amp modules are visible at the back, mounted on fabricated heatsinks made from some scrap aluminium I had handy.  Normally, the amps would simply be bolted to an aluminium base-plate, and that would provide all the heatsinking needed for anything short of continuous high power usage.

Figure 2 – Rear View of Completed Amplifier

At the rear, you can see the balanced XLR and unbalanced RCA connectors.  The switch selects between balanced and unbalanced (although the balanced input is disabled – see below for the reasons for this).  Output connectors are standard combination binding post types.  In case you were wondering about the apparent lack of a fuse, not so.  The IEC connector is a fused type.  Individual amplifier fuses are located at the power supplies.

The power transformers are mounted at the front of the enclosure to relieve some of the strain if (when?) I mount the amp in my rack in the workshop.  The power supply is between the transformers and power amps.  I used 4 x 8,000µF caps and a pair of 40+40V 300VA transformers, with the supply arranged as ‘dual mono’ (i.e. each amp has its own power supply, sharing only the mains lead, IEC connector and power switch or soft-start circuit.

This is overkill, and is not warranted for normal use – I did it that way simply because it was convenient at the time.  The modules are small enough that they will fit easily into a 1RU case (1¾” high).  This makes for a potentially very slim-line high power amp, but the transformers will pose a problem.  While a switchmode supply could be used, this is a more expensive option than a conventional power transformer based supply.

Construction

Apart from the power supply (described in detail below), the construction of the amp is primarily a mechanical exercise.  Having worked out where everything will go, and bearing in mind the requirement for good isolation of input and output leads, it is a matter of drilling the case and connecting everything together.

The modules use ‘fast-on’ (also known as quick connect) crimp lugs, although if you get uninsulated ones they can easily be soldered then shrouded with heatshrink tubing.

Figure 3 – Module Connections

Figure 3 shows the general layout of the module’s PCB.  The terminals marked in red are the only ones you need to get the amp working.  Those shown in blue are optional, and rather than give a complete description here, it’s better to refer to the data sheet [1].  The terminals shown in green are only needed if you must have the lowest possible amp dissipation.  Again, these are described fully in the data sheet.

While the volume control terminals are a good idea for some applications, in general I suggest that you use them.  This is from my own experience – while everything is fine for low level inputs, if your source can output more than about 1V RMS, you will run into trouble because the balanced input stage can clip.  When used in balanced or non-inverting single-ended mode, the stage has a gain of 2, but operates from a ±5V supply.  In theory, that gives you a maximum input level of 1.5V RMS, but with zero headroom.  Unless kept very short, the leads to the volume control also pick up considerable interference.

Speaking of interference … all PWM amps have the capacity to create interference, and the ColdAmp BP4078 is no exception.  While I have not found it to be a problem with the amp in its case, during initial tests my favourite FM station was almost completely blocked when everything was just sitting on the workbench.  The amplifier modules should always be inside a metal case of some description, as this provides shielding against RF interference.

Figure 4 – Recommended Wiring Scheme

The wiring scheme above is the same as I used in the final configuration shown above.  Note that the balanced input capability is disabled (the XLR connectors are wired as unbalanced).  I did use the fully balanced operation initially, but there was too much noise from the volume control wiring, and I ran into problems with input stage overload.  None of the ‘bells and whistles’ were used in this instance, because it was put together to assess the sound quality of the amp and take measurements.  While clipping into a load is easy, my speakers would explode if I ran the amp to full power into them, and even during extensive testing, I was never able to get the amps above slightly warm.

Note that the above diagram is intended to be literally interpreted.  The supply is shown in simplified form (see below for all the details), but the wiring should be done exactly as shown.  Do not be tempted to run the speaker return back to the amp board – take it directly to the supply star grounding point (the centre tap of the capacitors).  Input connectors are standard 3 pin 0.1″ headers, and the crimp connectors are readily available.  Personally, I don’t recommend that you crimp the connectors at all – they are more reliable if carefully soldered after performing a rudimentary crimp with a small pair of pliers.

Modules supplied by ESP will include the quick-connect (Fast-On) terminals and an input connector.  The input cable be twin shielded microphone cable, even for unbalanced inputs.  The negative input and shield are joined at the input socket (or the pot if used), and the input connectors should be isolated from the chassis.  In some cases, it may be advantageous to join the input ground to chassis with a 100nF ceramic capacitor – right at the input RCA connector.  This is something that you must experiment with, because different layouts will give different results.

Sub-Woofer Amplifier

It is to be expected that BP4078 amps will find themselves in many a sub-woofer, and they are absolutely ideal for this.  Because heatsink requirements are minimal, a simple flat plate can be used for a sub amp, making it very simple to build.  Incorporating extras like the P48 subwoofer controller (or P71 Linkwitz transform circuit) and/or the P84 subwoofer equaliser is no different from adding them to a Class-AB amp, and a suitable scheme is shown below.

Figure 5 – Subwoofer General Layout

The above is only a suggestion, of course.  The idea is to give you a general scheme that you can work with to suit your own purposes.  Because the BP4078 is so small, you get lots of room to play with on even a relatively modest sized panel, and with nothing more than a few holes to drill, it is much simpler to build than an equivalent sized Class-AB amplifier.

I will soon be able to add a photo of my own ColdAmp based subwoofer amplifier, which will replace the one I have at present.  The arrangement will be almost exactly what you see above, except a P48 board will be used instead of the P71 shown (since this is what I have now).  The other side of the panel needs a minimum of controls and adjustments – all I have at present is a level control, and that will not change.

Power Supply

WARNING :Mains wiring must be done using mains rated cable, which should be separated from all DC and signal wiring.  All mains connections must be protected using heatshrink tubing to prevent accidental contact.  Regulations where you live may demand that mains wiring be performed only by a qualified electrician – Do not attempt the power supply unless suitably qualified.  Faulty or incorrect mains wiring may result in death or serious injury.

The power supply for a PWM amp does not need to be quite as large as that for an equivalent analogue amplifier, because of the high efficiency.  Class-D amps typically run to about 90% efficiency, versus a maximum of 70% for Class-AB.  As a result, less power is expected from the supply.  In general, a transformer rated at the same power as you expect from the amplifier (on peaks – not continuous) is a good start, so for the schematic below, a 500VA transformer will be sufficient for a peak output power of up to 200W per channel (4 or 8 ohms).  You will be able to get more, but if sustained for any length of time the transformer will get hot and may be damaged.  If you expect to run the amps to close to full power continuously into 4 ohms, then you will need a 1kVA power transformer.

Figure 6 – Suggested Power Supply Schematic

The supply is fairly conventional, but a notable addition is C5 – this has not been shown on any other ESP supply to date.  The purpose of this cap is to help reduce conducted emissions – high frequency energy conducted down the mains lead.  You may also find that an EMI filter is helpful – you can get them integral with the IEC socket.

The fuse rating for F1 needs to be selected according to your local mains voltage, and it is usually best to check with the transformer manufacturer.  Assuming the use of a 500VA toroidal transformer, you can use the following as a guide (this also assumes that the P39 soft-start circuit is being used) …

Supply VoltageFuse Rating
110 VAC10 Amps
120 VAC8 Amps
220 VAC5 Amps
240 VAC4 Amps

In all cases, the fuse must be a slow blow type.  Even with the soft-start circuit, the inrush current may be much higher than the maximum average current.  For safety, use of an IEC socket with integral fuse is recommended.

Testing

Because the modules are fully built and tested, all you need to do is check your power supply before connecting the amplifier module itself.  The modules have protection circuits that will prevent operation below about ±30V or above ±68V, as well as overcurrent protection.  All you can do is connect the amp to a known working power supply.

For your initial tests, I recommend that you use a lamp (rated for your full mains voltage) in series with the incoming mains.  The lamp should be rated at about 100W, and will limit the current if there is a problem.  You will be able to operate the amp into a load at low power with the lamp still in series, but if you try to increase the volume too far the supply voltage will be reduced and the under-voltage circuit will turn the amp modules off.

It is imperative that you connect the power supply to the BP4078 modules with the correct polarity, and also make certain that the earth (ground) is solidly connected to the supply common.  Reverse polarity will damage the module(s) – the supply fuses will blow, but not before damage has been done.

Remember that with the values given for the power supply, you will be able to get 400W into 4 ohms, so be very careful with your signal input – there is a real risk of blowing speakers if you apply too much signal level.

Data Sheets & Additional Information

The BP4078 Data Sheet is a must read document before you start.  It describes all the options and also has the full specifications for the modules.

The BP4078 Application Notes provide more information again, primarily on how to use the modules, additional construction hints, etc.  Please take the time to read this information.

Intending purchasers should contact coldamp directly, or you may send me an e-mail with your query and I will pass it on.  If contacting ColdAmp, please mention that you obtained the information from ESP.

 

Copyright Notice.This article, including but not limited to all text and diagrams, is the intellectual property of Rod Elliott, and is © 2005.  Reproduction or re-publication by any means whatsoever, whether electronic, mechanical or electro-mechanical, is strictly prohibited under International Copyright laws.  The author (Rod Elliott) grants the reader the right to use this information for personal use only, and further allows that one (1) copy may be made for reference while constructing the project.  Commercial use is prohibited without express written authorisation from Rod Elliott.

Page Created and Copyright © Rod Elliott 18 Dec 2005