I thought that this thread was about making successful preamplifiers. Now, there are many factors in making a preamplifier. Good sound quality is one of them. Perception of value is another. Some people will NOT buy a piece of audio equipment UNLESS it is substantial in build quality. I just made 4 units for Japan. They like heavy duty cases, please don't blame me.
Now could I put this preamp in a pie tin and probably get away with it sonically? Yes, within reason. It wouldn't look like much, it might require using shielded wire on the inside, and we probably would not get any sales, even if the price was cut in 1/2.
It is like the fit and finish in an automobile. The best cars have expensive paint jobs and tight fitting doors. Cheaper cars will get you across town just as fast.
Mu-metal is nonlinear in any sort of magnetic field, and is pound for pound, very expensive. It isn't the best choice in my opinion.
Now could I put this preamp in a pie tin and probably get away with it sonically? Yes, within reason. It wouldn't look like much, it might require using shielded wire on the inside, and we probably would not get any sales, even if the price was cut in 1/2.
It is like the fit and finish in an automobile. The best cars have expensive paint jobs and tight fitting doors. Cheaper cars will get you across town just as fast.
Mu-metal is nonlinear in any sort of magnetic field, and is pound for pound, very expensive. It isn't the best choice in my opinion.
I recall being told similar on a tour of the Sonic Frontiers factory a dozen odd years ago. The amount of product shipped to some south east Asia countries was proportional to the percentage of exterior gold plated. In those markets it enhanced perceived value. What would be the preferred case material if cost and market appeal weren't factors? Being completely selfish here, the best case for moving $25K preamps isn't necessarily the best design choice for DIY. And some here (not me!) have access to extraordinary fabrication resources.
Speaking of aluminum enclosures to shield from magnetic effects....John have you ever investigated acrylic housings for your pre amps?
DNM and Tom Evans are two companies that come to mind. But of course as mentioned, the percieved value thing goes out the window. But it would be interesting to see the sonic effects.
DNM and Tom Evans are two companies that come to mind. But of course as mentioned, the percieved value thing goes out the window. But it would be interesting to see the sonic effects.
oops...on page 97 there is info about this. I guess that is what I get for not reading the last 50 pages of this thread.
We seem to be on the same theme Float, and I don't think it is any coincidence that both DNM and Tom Evans, who use Acrylic cases, also make extensive use of star grounding to remove the noise pickup you mentioned.
We seem to be on the same theme Float, and I don't think it is any coincidence that both DNM and Tom Evans, who use Acrylic cases, also make extensive use of star grounding to remove the noise pickup you mentioned.
Hi Agisthos,
I thought I would draw more comment from JC and others on this subject, particularly because many DIYers would find it easier to work with wood or acrylic rather than metal.
DNM and TE think that shielding/massive metal enclosures impact sound quality. A Blowtorch in an acrylic case may(?) sound better than in aluminium, but I guess it would be noisier in some environments, and as John knows so well, it would be harder to sell.
I still think this is an interesting topic for discussion.
I thought I would draw more comment from JC and others on this subject, particularly because many DIYers would find it easier to work with wood or acrylic rather than metal.
DNM and TE think that shielding/massive metal enclosures impact sound quality. A Blowtorch in an acrylic case may(?) sound better than in aluminium, but I guess it would be noisier in some environments, and as John knows so well, it would be harder to sell.
I still think this is an interesting topic for discussion.
Mr. Curl,
What is your personal opinion about preamp design that does not cancel harmonics? In your interview you mentioned your philosphy of designing audio gears, that is to eliminate all harmonics (distortion) as possible (you build cct with complementary differential).
But some designed preamps without any differential, so canceling harmonics is not the intention. Preamps like NP's NS10 or Naim or or McIntosh or JLH uses singleton input.
What do you think about this design philosophy?
What is your personal opinion about preamp design that does not cancel harmonics? In your interview you mentioned your philosphy of designing audio gears, that is to eliminate all harmonics (distortion) as possible (you build cct with complementary differential).
But some designed preamps without any differential, so canceling harmonics is not the intention. Preamps like NP's NS10 or Naim or or McIntosh or JLH uses singleton input.
What do you think about this design philosophy?
float said:
Hi,
So do I, or at least I did until I shared some of my relevant listening experiences on the "Bronze Heatsink" thread, a while ago.
Just look at the trouble that brought out of the woodwork from the resident 'know-alls', so I don't now consider it is worth talking about these matters in public Forums, unfortunately.
It just seems to cause too much ill-feeling.
Regards,
Hi John,
With regard to your case material and style. I fully agree with you. The product has to fit the market to be acceptable. If you have a great product that doesn't sell, what good is it? 😉
rdf,
My wife worked at Sonic Frontiers. The gold coloured case work when to the Asian market for sure. Much of this went to pride of ownership. See my comments above (as I agree with your post). But being a DIY'er means that we can come up with our solution with a little guidance. We are lucky to have some guidance here IMHO.
-Chris
With regard to your case material and style. I fully agree with you. The product has to fit the market to be acceptable. If you have a great product that doesn't sell, what good is it? 😉
rdf,
My wife worked at Sonic Frontiers. The gold coloured case work when to the Asian market for sure. Much of this went to pride of ownership. See my comments above (as I agree with your post). But being a DIY'er means that we can come up with our solution with a little guidance. We are lucky to have some guidance here IMHO.
-Chris
Hi Bob,
Things should be settling down here. Feel free to discuss thse things but everyone needs to remember to respect each other's opinion too.
Poobah,
LOL,
-Chris
Things should be settling down here. Feel free to discuss thse things but everyone needs to remember to respect each other's opinion too.
Poobah,
LOL,
What can I say? Hollow state it is!
-Chris
This TUBE Head-amp predates similarly styled cases from Musical Fidelity.
Now who designed this again ?
regards
James
Now who designed this again ?
An externally hosted image should be here but it was not working when we last tested it.
regards
James
anatech said:
Seemed like a nice place to work. My strongest memory of that tour is what looked like a wall of US Army 211's purchased for a product they never released. Always wondered what became of them.
I still own a pre-production SFP-1 - model number 'demo'. Bringing this back to topic, it's a great looking case with a real clunker of a design flaw. The power supply and audio sections are separated by a sheet of steel bolted to the chassis floor but otherwise unfixed. It resonates like a washtub bass, easily audible by tapping the top. I understand it was rectified in later runs.
Hi James,
Darn! 😡 There goes that marketing plan, would have gone well with poobah's liquid speaker wires.
rdf,
Yes, she enjoyed working there until Paradigm took it over. The two Chris' were a soap opera to watch. They were okay guys.
Some of that "metal" epoxy might work if you glue the edges to the sides. That would stop the ringing for sure. Give it a try.
-Chris
Darn! 😡 There goes that marketing plan, would have gone well with poobah's liquid speaker wires.
rdf,
Yes, she enjoyed working there until Paradigm took it over. The two Chris' were a soap opera to watch. They were okay guys.
Some of that "metal" epoxy might work if you glue the edges to the sides. That would stop the ringing for sure. Give it a try.
-Chris
Mr Curl -
I wasn't dissing aluminum as a shielding material. Folks were talking about combinations of material for shielding, and mu-metal seemed to be good candidate for magnetic shielding. Mu-metal or similar alloy foils aren't all that expensive compared to hogging out a solid block of aluminum.
However, I wasn't aware of any distortion problem with mu-metal, hence my question. I'm wasn't trying to jump down your throat or question your credibility, I just wanted to know if you had any idea regading the mechanism of the distortion increase, and its magnitude.
I must say I've picked up quite a few interesting things lurking on this thread. For example, there have been lots of threads on this site regarding subjective differences between volume controls, but here is the first time I've heard of measureable distortion introduced by a pot. Thanks for sharing your experience.
I wasn't dissing aluminum as a shielding material. Folks were talking about combinations of material for shielding, and mu-metal seemed to be good candidate for magnetic shielding. Mu-metal or similar alloy foils aren't all that expensive compared to hogging out a solid block of aluminum.
However, I wasn't aware of any distortion problem with mu-metal, hence my question. I'm wasn't trying to jump down your throat or question your credibility, I just wanted to know if you had any idea regading the mechanism of the distortion increase, and its magnitude.
I must say I've picked up quite a few interesting things lurking on this thread. For example, there have been lots of threads on this site regarding subjective differences between volume controls, but here is the first time I've heard of measureable distortion introduced by a pot. Thanks for sharing your experience.
Folks, I would think that silver would be the best candidate for a case, followed by copper, then aluminum. Thicker is actually better and will help make an aluminum case more effective against the magnetic field component of the E/M wave due to attenuation loss.
Steel, nickel, mu-metal etc tend to add a non-linear component to the audio signal. It may be small in amount, but many find it audible.
Acrylic, etc sounds OK to me, but it would probably be an even worse shield than aluminum.
As far as the round case is concerned: This was designed by Rod Herman who was my business associate back in 1979. It was paid for by A. Michaelson, then of Michaelson and Austin, now boss of Musical Fidelilty. I just designed the circuit inside.
Steel, nickel, mu-metal etc tend to add a non-linear component to the audio signal. It may be small in amount, but many find it audible.
Acrylic, etc sounds OK to me, but it would probably be an even worse shield than aluminum.
As far as the round case is concerned: This was designed by Rod Herman who was my business associate back in 1979. It was paid for by A. Michaelson, then of Michaelson and Austin, now boss of Musical Fidelilty. I just designed the circuit inside.
Yes, Rod Herman also did the circuit layout. It was kind of lousy. Picked up hum, even with a battery supply. Couldn't tell him anything though about his layout, because he quit and joined SOTA,
john curl said:
I'm curious as to your approach to layout. Are there any general guidelines you have followed over the years? What type of transformers do you prefer, rectifier topography, amount of filtering in the raw supply, grounding network layout, decoupling? Nothing you consider proprietary.
I'm curious because I find this topic to be interesting, yet rarely discussed (other than parroting and voodoo).
More important than feedback or RF pickup.
Mike.
john curl said:
Aluminium is a practical and good candidate for a cabinet. As John Curl says, thicker is better. It is also important that the joints between parts, e.g. top and/or bottom cover to the mains chassis connects well. Or else it will leak in and out here. The parts can for example come together with tongue and groove, or EMI gaskets located in a slit, or with other known EMC expelling techniques.
Rolv-Karsten
I don't do layouts. Carl Thompson, the 'T' in CTC is the layout expert. We use a lot of ground plane, high quality materials, and short path lengths.
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