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Old 12th June 2003, 03:03 PM   #11
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figure this -- the high end audio store is working on a 40% margin -- and it's justified by the slow inventory turns AND the risk of obsolescence, but knockdown 40% and you are probably getting at the invoiced amount to the store.

now look at the design of the amp or preamp cabinet -- not just the chasis -- the designers earn anywhere from $40 to $200/hour for the rough drawings to the CAD/CAM files used in final manufacture -- in my case of homebuilt stuff, as I have mentioned before -- I recycle chasis from used HP equipment, particularly power supplies, frequency counters, electronic switches -- doesn't look pretty, but you can buy an HP5328a counter for under $50 yet it would cost over $200 for the same 19" cabinet. If you don't want the power supply, just buy an old CISCO 2U cabinet.

My guess is that DIY'rs aren't doing multiple layer boards and trying to squeeze the last mil out of a trace separation -- this is good. The expense for DIY'rs is that proto-boards are expensive unless you cut them yourself.

components -- DIY'rs probably purchase better stuff.

risk -- some DIY'rs are more ready to experiment.

tweaks -- this is how many, if not all DIY'rs get started -- remember the term POOGE from Audio Amateur -- the "Progressive Optimization OF Generic Equipment"
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Old 12th June 2003, 08:46 PM   #12
sam9 is offline sam9  United States
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Default Here is an example.

Here is an example. One of the more popular or at least fairly well known DIY amps is G.Randy Slone's "OPTI-MOS". The design is good enough that will soon be going into production at ZUS Electronics.

From curiousity, I set the schematic up in a SPICE program to compare to other designs. I compared it to a couple of other published designs. At least as far as "the numbers" go, there are very few in the same ballpark. I have not built this particular design but have built a couple of others of his and the actual results are pretty close to the predicted results even when a comparative klutz like myself does it.

Rod Ellliot's designs are not so extemist but the woirst that can be said is that they perform as well as in not better than the better mass market units one finds at Circuit City.

PS: one aspect of the Slone design's I found is that choice of components is non-critical. At least in a SPICE model, you can swap to transistors of roughly the same specs without significant changes by-the-numbers performance. There is is only one capacitor, the input DC blocker that is truly in the signal path. This is bad news of a sort for obsesive tweakers since short of making some kind of drastic and unreasonable substitution you are unlikely seriously degrade the performance and even less likely to improve it.

What all this means (I think) is that you can build a DIY amp that is better than 90% of what "on-the-self" and for the other 10% you are in the relm of inaudible/insignificant differences.

HOWEVER, from my perspective the real advantage of DIY is that you can taylor the amp to your specific needs such as external dimentions and appearance, or specific functionality such as including an active XO PCB for a bi-amp system. etc.
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Old 12th June 2003, 08:56 PM   #13
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To confuse matters even more. Richard Clark, the car audio
celebrity has an on-going amplifier challenge where he
will give you $10k if you can hear the sonics of two
amplifiers being compared. This is done on his "test
bench" and there are certain rules, but essentially
he "zeros" out both amplifiers being tested to make
them "flat" and you audition both amplifiers not
knowing which one is which.

You can compare any two amplifiers, car or home audio, solid
state or tube as long as both amplifiers are operating at the same
power level. This test has been ongoing for years
and nobody has passed it yet, in other words, people
can't tell the difference between amplifiers when you "zero"
them out, an amplifier is just used to amplify a signal,
there is no magic hidden in the circuit topologies.

This topic has been discussed 1000 times on various
forums over the years, you can probably do an archive
search to find the details of the test.

If this interests you, this is his forum
http://www.carsound.com/ubb/ultimate...?ubb=forum;f=1

My preferences for amplifiers is simple.
Lots of power
Inaudible distortion (less than 1% THD)
Low impedance drive capability
Low noise
Operates in audio band

I don't car what class, what topology, tube, solid state,
bipolar input, jfet input, mosfet output, bipolar output,
just gimme an amplifier with those requirements and it's
all good for me.
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Old 12th June 2003, 08:57 PM   #14
tiroth is offline tiroth  United States
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A well built P3A will definitely outperform anything available at a mass-market merchant.
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Old 13th June 2003, 12:08 AM   #15
sam9 is offline sam9  United States
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Regarding the amp comparrisson mentioned above, I believe that one rule is that neither cqn be driven to clipping. The problem is that in real life a lot of amps get driven to that point, at least on peaks. Rod Elliot has written that he believe this is one of if not the primary source of difference people claim to hear -- i.e., how the amp behaves when clipping. In the range just below where you see clipping on a scope, didtortion rises above normal sometimes drasticly, so I'll opin that very likely that "sub-clipping" range is also a factor.

Tube amps are held to clip more gracefully and this is supossedly where some of their merits lie.

The brute force approac is to build monster amps and listen at reasonable levels, never getting close to clipping.
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Old 13th June 2003, 07:01 AM   #16
jcarr is offline jcarr  United States
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>Is it possible to homebrew better than the big guys?<

Depends on which "big guy" you are thinking of, and what your engineering and suibjective goals are, is it not? Given talent and a willingness to study and work, I am sure that it is possible for a DIY'er to homebrew better than many commercial designs. But when it comes to challenging the more innovative commercial designs - based on what I have seen from the DIY sector in Japan and various internet-based DIY communites - this happens once in a blue moon. Nevertheless, sometimes, someone will appear on the DIY scene who is very good. And if that person is extremely capable - he will most likely soon be head-hunted by a commercial audio or electronics manufacturer, or at the very least receive offers for consultancy jobs.

BTW, I am speaking of DIY'ers who design their own circuits and board layouts - implementing someone else's schematic or pcb layout is not a meaningful measure of design abilities, IMO.

>How do you homebrew better than the big guys.<

Study hard, work even harder, and always do your own thinking and analyses - question everything, don't take anything for granted, and be willing to take risks and innovate.

hth, jonathan carr
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Old 13th June 2003, 12:54 PM   #17
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Default Re: Is it possible to homebrew better than the big guys?

Quote:
Originally posted by walker
OK, so it should read “How do you homebrew better than the big guys,” (major HIFI companies).

I would like your thoughts on what are the major design issues that lead to a great amp.
My opinions on this:

1. Make sure you have adequate power output / current drive capability. (Many commercial amps would be fine except they run out of headroom because compromises are made with the very cost-sensitive PSU components).

2. Get the grounding right. The easiest way to do this is to consider that, for every current flowing down a wire or track, a return current is coming back somewhere to complete the loop. (This is usually a ground wire). The current flow produces a voltage across the wire's finite resistance, hence 'ground' potential varies along its length. So, make sure current return paths are separated so that ground voltage errors aren't coupled from one part of the circuit to another.

3. Fix inductively-introduced problems. Current flowing round a loop creates a magnetic field depending on the magnitude of the current and the area of the loop. Such a magnetic field will induce voltage errors in other loops (such as a signal line and its corresponding ground return connection) depending on the area of the loop and its orientation relative to the source. So keep the wires/tracks which take outflowing currents close to those which take the return currents, and keep them away from (or orient them differently to) small-signal wires and tracks. This is particularly important with split-rail PSUs - sometimes the current path will be between the + rail and the speaker, and sometimes between the - rail and speaker.

4. Fix capacitively-introduced problems. A conductor with a large alternating voltage on it will introduce a small voltage on neigbouring conductors (depending on the size, spacing and impedance of the input). This is only really likely to happen in a power amp if you fail to ground the metalwork properly, or route the input wires near the high-voltage stuff.

5. Most commercial amps are constrained to a particular physical form factor, with inputs and outputs on the back panel, and a knob on the front, just so it looks marketable. You don't have to stick to this, so don't if it makes the layout easier.

6. The single most important component selection in terms of quality is probably the volume pot.

Cheers
IH
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Old 13th June 2003, 01:12 PM   #18
protos is offline protos  Greece
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I wouldn't say that you can do better than the top hi-end components but you can do as well or better at the mid hi - end level and at considerably less outlay.
I am always surprised that at the low end of audio you can get so much for so little nowadays.A few hundred euro for CD , tape , radio , amp and speakers- try diying that!
And I still cannot believe that an amp or pre-amp can retail for 20.000 or 30.000 euros even if it's state of the art. It probably only has about 500 euros worth of generally available parts (at manuf prices not diy catalogue prices) and perhaps a chassis that may cost another 500 euro maximum (for big two chassis monoblocks etc) to produce in quantities.
So the rest is overhead ,"research & dev." , rents , salaries, holidays and a big Jaguar for the manufacturer.
It's a little bit like haute couture - if you( I mean your other 1/2s) get a dress personally made for you by Mr. so and so designer you are going to pay tens of thousands of euro but if having the skills you copy the same dress at home it will cost you not even 100 euro.
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Old 13th June 2003, 02:16 PM   #19
jcarr is offline jcarr  United States
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Protos: I have a commercial preamp (Connoisseur 4.0) which retails for somewhere in the general vicinity of 20,000 USD, and my cost for the electrical parts alone is far, far greater than 500 Euros. The chassis, associated metal work and cabinetry are likewise _very_ much higher than 500 Euros. Perhaps manufacturing costs in Japan are more expensive than in other countries, but I think that you grossly overestimate the profit margin for an audio electronic manufacturer (at least in my case).

>a big Jaguar for the manufacturer.<

Completely out of the question. If I had that kind of spare cash - and that is a very big if - undoubtedly I would invest it on a new development project. Only the development cycle of a new amplifier will typically eat up around 150,000 USD, and when gearing up for the production of a new design, parts need to be purchased in serious quantities - in my case I find that I need to allocate at least 100,000 USD for each production run . Much of this sum needs to be paid to the supplier at the time of ordering, and the delivery of the parts is usually delayed by 8~12 weeks. Then the production means another delay, and shipping, promotion and sales each incur additional delays. In many cases, I won't start to see a return on that 100,000 USD investment until perhaps 6 months have passed. And then I need to start paying back or recouping the 150,000USD debt that I ran up during the development cycle.

>if you get a dress personally made for you by Mr. so and so designer you are going to pay tens of thousands of euro but if having the skills you copy the same dress at home it will cost you not even 100 euro.<

In my opinion, it takes years of diligent study, thinking and work to pick up the skills required to design audio products that multiple markets regard as being among the world's very best. Meanwhile, you need to eat and get the rent paid, so it is easier if you can manage to pick up an advanced technical foundation during high-school and university, rather than after you become a (supposedly) self-sufficient adult.

Besides, I think (or hope) that a designer with talent, dedication and pride will never stop pushing himself or learning, so the skill level required to match or surpass his creations is definitely a moving (climbing) target. For every new design, I make it a point to come up with a new idea, and preferably tricky enough so that I need to sweat hard at every stage - from calculation/schematic design through manufacturing consistency and the performance and reliability of the production units.

hth, jonathan carr
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Old 13th June 2003, 03:13 PM   #20
protos is offline protos  Greece
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jcarr,
I do not mean to disrespect what you are doing and I think that if there is a market for a niche performance product at ?????0000 USD then go ahead and sell it - that's what free economy is all about. In the end if a competitor can come up with the same sounding product at 5,000 USD then it's also to everyones benefit.
As to parts cost I don't doubt what you are saying about your particular costs , especially the chassis part which I have seen in a photo. However I doubt this is the case for most hi-end manufacturers where most of the time it's just a thick square aluminium box construction with some heat sinks. As to the parts inside I still have serious doubts about how many dollars worth of electronics you can stuff ina box seeing that most are costed in cents worth.Even with Vishays ,BG's etc it's just not going to add up to more than 1000 euro (unless you silver plate everything)
The rest of your post just proves that what we are paying for is the time , rent , interest , packaging , research of the producer which is of course acceptable in all economic systems but which the DIY er does not need to spend on.
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