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costasx 22nd January 2013 12:55 PM

Amplifiers and cost constraints.
I don't know whether such an irrelevant topic is suitable for discussion here.

Everyone has his methods on how to design Hi-Fi power amplifiers, his favourite topologies, BJTs FETs cascodes, A/B/C/D/E/.../Z class, reg/unreg PSUs etc so that the best result is achieved.

I guess that sometimes, some of us have to design amplifiers having cost in mind, like 'an X watts amp that costs up to 150 or 200', ie cost dictates everything and several sacrifices must be made.

I wonder how would you distribute that 150-200 budget among PCBs, PSUs and semiconductors assuming that:

0. the product must have decent Hi-Fi performance and worth every penny of the 150,
1. assembly and test costs are negligible,
2. the finished product will have 2yrs warranty, therefore all sorts of protection will be included in the design and all parts should last at least that long,
3. the unit must be suitable for small volume production (10-12 units per day)
4. only a few measurements and adjustments needed to test and calibrate the product,
5. all parts should be readily available and from many sources.

In an amplifier apart from the electronic parts, several other pretty ordinary things are needed, like switches, fuse-sockets, chassis, knobs, indicators, heatsinks, fasteners, sockets, nuts, screws etc. Please include them in your budget.

If you think that the cost distribution can't be calculated because it's either too complex or time consuming or country-dependent or just irrelevant, then please tell the cost % of the subsystems in the amps you have built. (not purchased)

DF96 22nd January 2013 02:24 PM

Define 'decent H-Fi'. Retail or wholesale cost? Genuinely CE compliant?

You appear to be asking for significant but free product development consultancy. Many of the issues are irrelevant to DIY audio.

Class E (and F!) won't work too well for audio unless you want a single sine wave at a frequency known and fixed at design time.

costasx 22nd January 2013 04:56 PM


Originally Posted by DF96 (
Define 'decent H-Fi'. Retail or wholesale cost? Genuinely CE compliant?

Let's assume we have been given 150 to buy the components and parts and hand in 1 day later a power amplifier, a finished product ready to work. Wholesale and retail prices are too complex for me, yet.
The CE compliance isn't a priority for now, it's too premature though it would be in the wish list should the prototype be successful.
I can't define the 'decent Hi-Fi', at least with numbers. An entry level amp for a student or a poor man in a small flat, capable of delivering 10W+10W (at least) with good figures or "merit", ie 0.1% THD+N, 0.1% IMD, 10Hz-40kHz etc. All the numbers aren't exact or mandatory. Can be better or worse. Basically as good as it can be done subject to the 150.


Originally Posted by DF96 (
You appear to be asking for significant but free product development consultancy. Many of the issues are irrelevant to DIY audio.

No, far from it, I am an individual. Yes, many are irrelevant to diy and audio.


Originally Posted by DF96 (
Class E (and F!) won't work too well for audio unless you want a single sine wave at a frequency known and fixed at design time.

I agree, they certainly don't work well, I was trying to be humorous and at the same time not to impose any restrictions in the design. I failed.

If you think that for any reason it can't be done or you can't disclose, it's OK.
BTW I guess you have built many amps, you don't spend 90% of the cost in the enclosure and flashy panels...
What do you think?

sreten 22nd January 2013 06:04 PM


FWIW I wouldn't even attempt to build a budget amplifier,
a good expensive one is an entirely different ball game.

Many moons ago my sisters boyfriend stuck a copy of Everyday
Electronics (I think is was) in my face enthusiastically saying
he wanted to build the 70 kit amplifier featured that month.
A hideously cheap thing to meet that price, as would be 150
today, the grimness of it I can't quite recall, but it was bad.

I got him in his car and we drove to Comet. I pointed at a 50 Trio
amplifier (half price I recall), and said " just buy that", and he did.

Nowadays my favourite budget amplifier is the Pioneer A-300X.
Superb build quality with parts that would cost a small fortune
at an ordering level of 10 a day, for about 70 to 80 used,
and sometimes a lot less, under 40 the last one on e-pray.
It also sounds rather splendid for what it is, decent phono too.

I'd estimate what you could build and make a profit with in the UK
for 150 would look pretty much like 30 offerings from China.
Its a non-starter, you have to go up market for UK manufacture.

rgds, sreten.

DF96 22nd January 2013 06:12 PM

Build and debug an amplifier in 1 day? It would have to be a straightforward case of 'datasheet designing' of a chip amp. Much of the cost would be hardware: metal bashing, switches, sockets etc. plus a decent mains transformer.

aardvarkash10 22nd January 2013 11:02 PM

Camp Amp.

Job done. Next please.

JMFahey 22nd January 2013 11:19 PM

In 1 day it's impossible, even if you got a full kit.
As of: 3.

the unit must be suitable for small volume production (10-12 units per day)
How many will be built during the first year?

googlyone 22nd January 2013 11:33 PM

One day build is well and truly possible, but to achieve this you need to productionse the design. This would be things like buying in batches of loaded pcbs, CNC punched and machined cases and brackets etc.

This represents a major up front investment.

Along the same lines, getting materials costs down requires link g up suppliers with large orders, again up front costs.

Integration and test requires skilled staff with test jigs, procedures and in my experience automated test equipment. Not hard but expensive.

You could do the above, but need confidence you have the ability to sell the (rather large) stack of product you have.

The quality of build you get without the above is almost always "really good" but just that bit home made. It doesn't fuss most of us as hobbyists - we look through the bling and see what lays beneath. Most of your customers don't.

Then there is the route to market. .....

sreten 22nd January 2013 11:37 PM


Originally Posted by costasx (
and (be) worth every penny of the 150,


That is the utterly hopeless requirement of a UK build.

rgds, sreten.

regiregi22 19th February 2013 12:58 PM

Aren't you guys able to assemble a simple gainclone in one day, let's say, 12 hours of hard work?
I think that the deciding factor would be enclosure workmanship, it can range from already factory made to scratch work from raw metals.

I you already have the case (let's say a Modushop one), soldering components to boards is no more than 1-2 hours, then drill all proper holes in the case, another 1-2 hours, and how much do you need to cable two dozens of wires?

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