Help with identifying some caps and their values on a phono preamp

[mlloyd1]

Hmmm....

Polystyrene caps. Why am I feeling this sudden strong urge to volunteer to be someone Per is not fond of

mlloyd1

Originally posted by Fred Dieckmann


You should give them away to someone you are not fond of. They are not practical for you it sounds like, and would be an extreme pain to use.

[peranders]

Originally posted by mlloyd1
Hmmm....

Polystyrene caps. Why am I feeling this sudden strong urge to volunteer to be someone Per is not fond of

mlloyd1

he, he... It's not fond of or not for me. I just don't use them. Maybe I should get rid of them?

[jcarr]

Peter:

>Having the wood block milled out to a required shape, and then painted inside to eliminate RF interference, makes it a nice starting point for a chassis. It's probably better than metal chassis, as wood affects electrical circuits less than metal (sonically, or at least in a different way).<

I don't altogether disagree, but bear in mind that the circuit bandwidth, physical size and local RF conditions have a significant effect on what types of chassis materials and constructions you can safely use. With clean RF conditions, you may be able to use damn near anything for the chassis. But in a dirty environment (as in many big cities), you may need compact circuitry with heavy input low-pass filtering inside a copper-plated steel chassis (look at some of the Japanese gear, like those from Marantz or Pioneer).

>I also suspect that it's not coincidence that the board is not attached to the wood by screws and usual standoffs but it's done by using hot glue (I suspect).<

Differences in the environment (esp. temperature and humidity) can have a profound effect on the dimensional stability of wood. When you use wood, it is best to not rely on it for long-term dimensional accuracy, and incorporate floating structural concepts, so that the wood can move as much as it wants to without affecting subassemblies that may be attached to the wood. If you try to constrain wood so that it cannot move much, it may develop cracks and/or warps after some years in the field.

>I am still impressed by the engineering choices made in constraction of this little wonder, and I definitely use some of them to inspire my future projects (the cheap ones at least ).<

In the end, as long as you can make your choice work to your satisfaction, and it doesn't create problems in the field, anything is ok. As you may know, we have also used wood in a number of our designs. While the older Connoisseur Model 1 and 2 used full-enclosure-type wooden cabinetry, based on my experiences with these older designs, I have limited the use of wood in the more recent designs (Connoisseur 3, 4 and 5) to the front panel and sides.

>Any idea how it performs?<

There is a new thread about the Grado RS1 headphones and RA1 phono stage on PinkFish. Check out:

http://www.pinkfishmedia.net/forum/s...&threadid=1090

regards, jonathan carr

[Fred Dieckmann]

This is a $500 product and dealer cut is probably 40% to to 45%

http://www.gradolabs.com/product_pages/phono_amp.htm

Frank Lloyd Wright said "form follows function". Mechanical noise is an issue for low level circuits and hot melt glue is excellent for damping and probably adds significantly to the sonics. Us cable designer have been using it for years. The enclosure is attractive and sets it apart from other products in it's price range. Most customers don't take stuff apart to see how it is made. Designing very good products in high end audio at reasonable prices is often more of a challenge than expensive products with practically unlimited parts budgets. Say, isn't Grado a competitor to......... never mind.

Planning another product? Perander$

BTW I don't think that is the complete schematic from the circuit description on
the website.

[peranders]

Jonathan, you took the words from my mouth. Can the Grado box get any approvals at all? How good is really conductive paint as shield really (in combination with two not very good connected plates)? I see also very poor decoupling of the amp. This is sharp contrast with ordinary japanese amps with too much filtering....

[Fred Dieckmann]

">I am still impressed by the engineering choices made in constraction of this little wonder, and I definitely use some of them to inspire my future projects (the cheap ones at least ).<"

Good save Mr. Carr! I thought you were going to drop that pop fly for sure.

[peranders]

Originally posted by Fred Dieckmann
Planning another product? Perander$

Yes, this amp look very interesting but first I have to convert my religion to minimalism.

[Fred Dieckmann]

Originally posted by peranders
Jonathan, you took the words from my mouth. Can the Grado box get any approvals at all? How good is really conductive paint as shield really (in combination with two not very good connected plates)? I see also very poor decoupling of the amp. This is sharp contrast with ordinary japanese amps with too much filtering....

They will just have to sell them over here I guess. I thought the whole point of the CE approval was to keep European products from having to compete with American products. The 0.1 uf ceramics parked right next to the op amp seems like pretty good high frequency decoupling. It's an analog circuit that shouldn't radiate RFI and most of the RFI pick up is often from the cartridge and tone arm wiring. That might be an op amp with good RF characterists also, since they seem to be getting faster everytime I read a new data sheet.

Man I wish I could do that much engineering analysis from picture of a part without a part number. I'm just not that smart.

[jcarr]

Fred:

>Mechanical noise is an issue for low level circuits and hot melt glue is excellent for damping and probably adds significantly to the sonics.<

I've tried hot-melt and other types of damping on high-gain circuit boards, and I have to say that I never subjectively cared for the results. Based on my own experience, I may consider using component damping in a speaker crossover, and perhaps also for part of the output stage of a power amp, but most probably not for low-level circuits.

>The enclosure is attractive and sets it apart from other products in it's price range.<

I've seen a number of speakers and wood-based audio products run into problems in Japan, Taiwan and Hongkong. Now when I see wood used in an audio product designed to be sold world-wide, the potential for cracks and warpage (and RFI pickup) come immediately to mind. Perhaps the RA1 doesn't have any cabinetry problems, but my experience with that type of construction makes me a little wary. And conductive paint as RFI treatment may not be sufficient in some environments.

>Designing very good products in high end audio at reasonable prices is often more of a challenge than expensive products with practically unlimited parts budgets.<

Trust me, whether the production budget is $100, $1000, or over $10,000, it _always_ feels limited. Whether you are designing a cheap product or an expensive one, the point is to wrack your brains and come up with a design and production method that squeezes the biggest perceived value out of whatever the budget may happen to be. That is the challenge, and that is what makes it all fun. A bigger budget doesn't necessarily make the design and engineering process any more entertaining or rewarding.

regards, jonathan carr

[peranders]

Good for you Fred that America has a very good RF environment and/or all electronic equipment have no problems with RF.

Seriously Fred, you are joking, right? Sure you are because you know what RFI and EMI is all about?

EMI and RFI is everywhere all the time. This is mostly the only thing I'm worry about.