150W > cheap, simple, bass power amp?

theb0b

Member
2012-06-11 12:33 pm
I have 4x 15inch bass scoops. Loaded with 150W 8 ohm Instrument drivers.

I use them with an active crossover at 310 Hz. I'm looking for a robust design with easy to obtain, cheap components.

I've considered a Quasi after reading this thread,

http://www.diyaudio.com/forums/solid-state/167394-quasi-amplifier-beginners.html

2N3773's apear to be unobtainable. 2N3055, don't appear powerful enough. 2SC5200 seem to be the only option.

Should I be looking for a Mosfet design? I think class D looks too difficult.

I'm pretty sure that transformers are going to be the largest part of the cost, so efficiency should be taken into account.

I dont mind etching my own boards, but I'm not knowledgeable enough to design one.

What should I be looking at? I'm imagining 4x Class B mono blocks.

( First post so be kind)

Thanks for your input.
 

theb0b

Member
2012-06-11 12:33 pm
I'm plodding through the B500 thread at the moment.

As much as I love ESP designs, I have bought boards from there before. I find the site bewildering, the descriptions to be ambiguous and the forum at times to be hostile to beginners.

The B500 looks like what I'm looking for. Apexaudio is the man!
 

theb0b

Member
2012-06-11 12:33 pm
Thanks AndrewT, I always appreciate your posts.

Unfortunately I can only find his Facebook page, and that is a site I avoid at all costs! If you could provide a link, I'd be grateful.

There is a huge amount of information in the D500 thread...

http://www.diyaudio.com/forums/solid-state/164208-500w-pa-amplifier-limiter.html

I'm slowly working my way through it. It appears to be an excellent solution for my requirements.
 

theb0b

Member
2012-06-11 12:33 pm
Personally, I find his descriptions to be outstanding. I'm a fan of Elliott's; I got a few ideas from his work. But his stuff is not for beginners, and he states this quite clearly in many of his project descriptions.

Not intending to be belligerent, but the quoted link to his excellent 300/500W Subwoofer Amplifier, is a good example. Why doesn't he just state which drivers and output devices are recommended, rather than using multiple, ambiguous anaphoric references in various updates?

This "flowery" style, in my opinion, needlessly complicates comprehension. Technical writing should be clear, concise and unambiguous. The site is archaic, lacks structure, is difficult to navigate, and forces new pages to open unnecessarily.

This is unfortunate because the site contains a wealth of information, unavailable from other sources, and is truly one of the best repositories of information for the hobby. His designs and knowledge are outstanding, but the presentation of that information is distracting.

I have enjoyably built several of his projects. Unfortunately the cluttered, ambiguous documentation, was detrimental to the experience.

Technical writing is a specialized field, many great engineers have failed to adequately master it.

(I hope this doesn't come over as rude, that isn't my intention.)
 

theb0b

Member
2012-06-11 12:33 pm
Theb0b,
you do a dis-service to the ESP site.
The information that you credit the site with having, sometimes unique must have taken years of full time effort to compile.
It matters not that the writing style or presentation is archaic.
The content is what matters.

At the risk of flying completely off topic, after rereading my last post, I think I have been more scathing than I intended. I apologize for my previous post and I hope that no offense was taken by either Rod Elliot or anyone connected with ESP.

I understand that the site has grown "organically" and that revision would be a gargantuan task.
 

theb0b

Member
2012-06-11 12:33 pm
I'm also not sure what you mean by Rod not stating what the recommended transistors are. Looking at the page, it's the MJL4281/MJL4302 for outputs, and MJE15032/3 for drivers.

It sounds like you really want a complete kit, rather than just a PCB.

That isn't what I want at all. Component availability is one of the largest challenges in the hobby these days, and a coherent and available BOM, often becomes the deciding factor.

I understand that some people enjoy ferreting out obscure components and consider that to be a rewarding part of the hobby, but many others prefer to be building projects that they can test and customize.

I really don't want to disrespect the site but does he really recommended MJL4281A and MJL4302A output transistors?

Farther down the page he also says...

"Although I have shown MJL4281A and MJL4302A output transistors, because they are new most constructors will find that these are not as easy to get as they should be. The alternatives are MJL3281/ MJL1302 or MJL21193/ MJL21194."

He then goes on to say...

"Note: It is no longer possible to recommend any Toshiba transistors, since they are the most commonly counterfeited of all. The 2SA1302 and 2SC3281 are now obsolete - if you do find them, they are almost certainly fakes, since Toshiba has not made these devices since around 1999~2000."

Does this mean to never use any Toshiba devices at all, or just exclude the 2SA1302 and 2SC3281?

But then the last update to the page was was almost 10 years ago. Considering that he is using this page to sell his product, it seems a little poorly documented.

His projects are extremely valuable for the schematics, but it is quite risky buying a PCB if you don't know if the components are available. Some of his projects don't even contain a full schematic or BOM.

Still this thread has been extremely useful because of the excellent suggestion of the Apex B500, and the designs by QUASI. I'm still only about half way through the B 500 thread, there are so many useful and interesting configurations.

Thanks everyone for your contributions.
 

ATAUDIO

Member
2011-05-01 10:56 am
Wien
-quasi-amplifier-beginners.html

2N3773's apear to be unobtainable. 2N3055, don't appear powerful enough. 2SC5200 seem to be the only option.
I am not so in agreement with your preferences. You quote either old technology stuff 2N.. that are rightly difficult to obtain in good shape, or poor SOA devices, that I do not in general recommend for a tough use.

The choices of ESP , on contrary,
quote>
"Although I have shown MJL4281A and MJL4302A output transistors, because they are new most constructors will find that these are not as easy to get as they should be. The alternatives are MJL3281/ MJL1302 or MJL21193/ MJL21194."
unquote>

seems to me right on spot if you want modern, affordable, available, BJTs for the scope of your build.

Then, if you indeed are an old-minded estimator of TO3 cans ( as I am ...) then I would recommend you MJ15003/4 .They are still available by major distributors, and extremely rugged. With two pairs at 55 V rails you will easily handle that 150W even in the worst situations, design of your choice. Sombebody would even allow for a single pair, but not me.
 
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Not intending to be belligerent, but the quoted link to his excellent 300/500W Subwoofer Amplifier, is a good example. Why doesn't he just state which drivers and output devices are recommended, rather than using multiple, ambiguous anaphoric references in various updates?

Devices are discontinued and superceded. His updates help you with that. ;)

With some familiarity of transistor types and the ability to read a data sheet, you could figure out which devices would work by yourself. It's part of the hobby.

This "flowery" style, in my opinion, needlessly complicates comprehension. Technical writing should be clear, concise and unambiguous.

My opinion is that his writing is quite clear, concise and unambiguous. People that are well versed in this hobby often want to alter circuits, and Rod certainly acommodates this. Furthermore, he clearly states that his projects are not for beginners.

His designs and knowledge are outstanding,

Not only that, but they're versatile if you know what you're doing.

I have enjoyably built several of his projects.

That tells me that you have some level of proficiency. Now you have to ask yourself if you can handle this project.

You might be better off getting some kind of kit. If not be sure that you have a clear understanding of what you're doing before you start.
 
Not intending to be belligerent, but the quoted link to his excellent 300/500W Subwoofer Amplifier, is a good example. Why doesn't he just state which drivers and output devices are recommended, rather than using multiple, ambiguous anaphoric references in various updates?

This "flowery" style, in my opinion, needlessly complicates comprehension. Technical writing should be clear, concise and unambiguous. The site is archaic, lacks structure, is difficult to navigate, and forces new pages to open unnecessarily.

This is unfortunate because the site contains a wealth of information, unavailable from other sources, and is truly one of the best repositories of information for the hobby. His designs and knowledge are outstanding, but the presentation of that information is distracting.

I have enjoyably built several of his projects. Unfortunately the cluttered, ambiguous documentation, was detrimental to the experience.

Technical writing is a specialized field, many great engineers have failed to adequately master it.

(I hope this doesn't come over as rude, that isn't my intention.)
Rod Elliot dont know technical writing? I dont think so. I have been to there frequently and I think he has done a great job. I always easily find what I am looking for. You think you were not rude? but yes, you are. Considering the time and effort rod has spend for compiling all that gems in his site.