Hmm, emirr:OPA1642 make a rather fine MM phono stage with several fringe benefits
"In general, only the noninverting input is tested for EMIRR for the following three reasons:
• Operational amplifier input pins are known to be the most sensitive to EMI, and typically rectify RF signals better than the supply or output pins.
• The noninverting and inverting operational amplifier inputs have symmetrical physical layouts and exhibit nearly matching EMIRR performance.
• EMIRR is easier to measure on noninverting pins than on other pins because the noninverting input pin can be isolated on a printed-circuit-board (PCB). This isolation allows the RF signal to be applied directly to the noninverting input pin with no complex interactions from other components or connecting PCB traces."
From:
OPA1642 Sound-Plus High-Performance, JFET-Input Audio OpAmps | TI.com
Hey Bill, what are the 'fringe benifits'? Is that like 'friends with benifits'?
Cheers,
Jeff
To be fair, better than spec sheet numbers should cause a raised eyebrow. However Tom is honest, has the test gear (and knows how to use it) and does know people involved in the LM3886 team at Natsemi(as was). So the numbers are likely correct.
Edit: ref 1642 Fringe benefits are both Self and Curl think it's a bad idea
Edit: ref 1642 Fringe benefits are both Self and Curl think it's a bad idea
"
Here be #377 The Spinach Scholar . Olive tells Popeye that she's through with him unless he goes back to school and gets an edumacation. Popeye enrolls .
"
Actually I was thinking Homer not Popeye (but Pop's the orig)...
But that could be an age thing ... teeheee! (I'm only 47)
Last edited:
"
Here be #377 The Spinach Scholar . Olive tells Popeye that she's through with him unless he goes back to school and gets an edumacation. Popeye enrolls .
"
Actually I was thinking Homer not Popeye (but Pop's the orig)...
View attachment 672815
But that could be an age thing ... teeheee! (I'm only 47)
A good lesson less is new than you think. The chance that the writers didn't grow up with Popeye is small. My wife went to a seminar with Bart's voice actor unlike a lot of celebrities they had no problem talking in character all the time.
Last edited:
I take it you're refering to the Gaincard:
6moons audio reviews: 47 Laboratory Model 4706 GainCard
No emi on the input, no zobel or anything on output, 1000uf ONLY ps caps, wide ps loop area, ...
"...
To deliver the freshness of the sound
Extreme simplicity ----- minimum circuitry
Powerful voltage regulation
True values of NFB
Rigid and compact chassis structure
.."
In the words of the master, 1995:
"...
In case of op-amps, the oscillation happens at really high frequencies, like in 100MHz or 200MHz, and you can't check them with normal oscilloscopes which are usually capable of up to 20MHz range.
Then I realized something else. The temperature!
To solve this oscillation problem, I hit upon an idea to solder the resistor for NFB directly to the feet of the op-amp instead of on the circuit board. In my case, the op-amp has eight feet and the NF resistor comes between the foot No.3 and No.8. This is really the shortest length imaginable.
On the circuit board, there are patterns of 5mm each, plus the length of feet themselves and the length of the feet of the resistor. These add up to a big difference in the scale of op-amps. The effect of this approach appeared in the difference of the operating temperature of the amplifier.
..."
op-amp
He should have used an LM1875!!!
"...
Features:
World's smallest number of parts - 9 parts per channel( excluding attenuators )
World's shortest signal pass length - 32 m/m ( including the length of parts )
World's shortest NFB loop length - 9 m/m ( including the length of the resistor )
World's smallest filter/condenser - 1000µF, (50W version - 2200µF)
Dual mono construction with each channel in a separate chassis.
Rigid and compact aluminum chassis construction to release vibrations smoothly.
Separate 12-position attenuators for each channel.
Can be up-graded into a pair of complete mono amplifiers by adding another Model 4700 Power Humpty.
"
4706
"9 parts per channel", I guess they forgot about:
and more like:
Last edited:
6061 is a general purpose structural alloy with uses in aerospace, I use it in my chassis. It's relatively inexpensive compared to many other AL alloys, or was.
AL alloys are confusing to me. The only ones I have ever worked with are 2000 series and 6000 series.
Hopefully you caught the subsequent banter, but I'm in full agreement. 6061 takes to anodizing well too, which is certainly an added benefit for audio chassis.
Sorry that's
and
Ohh and:
"
Model 4706 "Gaincard" Amplifier unit
MSRP US$1,850.00
"
Last edited:
Absolutely a good lesson, it's all been done!
I've edumacated my 7 'yr ol son in the classics:
Outer limits
Batman ('66)
Spiderman ('67)
Star Trek
G force
Star Wars
Matrix
...
Classic rock
Classic hip hop/rap
...
Psycho
Alien
Terminator
Halloween
Orig It
...
A CBC interviewer was gobsmacked every time Nancy dropped into Bart:
The Simpsons star Nancy Cartwright goes In Search of Fellini in her latest film | CBC Radio
Last edited:
Life is funny that way, over the last week I caught up on a few Outer Limits episodes, as well as Alien 3 which I missed first time around. BTW I have an original art Carmine Infantino page from the first redesign of Batman.
https://www.mouser.com/pdfdocs/NichiconESaudiocapsdatasheet.pdf
Not a bad start. High as voltage as you can lay out will be a good thing. And Panasonic/United Chemicon/Cornell Dubilier all have their respective high performance series of bipolar electrolytics.
You guys 'certainly carry on', much like envious college sophomores. '-)
Now, PMA is referring to the CTC Blowtorch because our thick aluminum case had potential flaws in picking up RFI. And he may be right, but we did not make any deliberate mistake.
The ALUMINUM case was to replace a steel case that might effect the electronics by inducing distortion.
The THICK aluminum case had several advantages: It shielded out lower frequencies, including hum frequencies to some extent because of its added thickness. It made a sturdy box that did not rattle or even resonate much, and it became a sturdy anchor for the military grade
Shallco switches that are pretty stiff, as well as the TKD pots that are nearly as stiff to turn. In the end, we 'hogged out' solid billets of aluminum, but we tried aluminum welding first. We made our first prototype this way, but we decided that the chance for external marring was too much for this approach. Our customers, besides our own personal friends were often very touchy as to what an outside surface looks like, as much as how it performs, and I found this to be so, even beyond what we first expected.
We did not RFI test the box, so PMA might have a point, but added internal shielding would have changed the sound quality so we did not use it, because we thought we have kept the box RFI sealed adequately, at least for lower frequency RFI, so we just separated our silver wires from each other, (that is why they are not neatly bundled together) to keep the Xtalk at a minimum.
All in all, we never had any complaints from our customers or ourselves, only PMA. Go figure! '-)
Now, PMA is referring to the CTC Blowtorch because our thick aluminum case had potential flaws in picking up RFI. And he may be right, but we did not make any deliberate mistake.
The ALUMINUM case was to replace a steel case that might effect the electronics by inducing distortion.
The THICK aluminum case had several advantages: It shielded out lower frequencies, including hum frequencies to some extent because of its added thickness. It made a sturdy box that did not rattle or even resonate much, and it became a sturdy anchor for the military grade
Shallco switches that are pretty stiff, as well as the TKD pots that are nearly as stiff to turn. In the end, we 'hogged out' solid billets of aluminum, but we tried aluminum welding first. We made our first prototype this way, but we decided that the chance for external marring was too much for this approach. Our customers, besides our own personal friends were often very touchy as to what an outside surface looks like, as much as how it performs, and I found this to be so, even beyond what we first expected.
We did not RFI test the box, so PMA might have a point, but added internal shielding would have changed the sound quality so we did not use it, because we thought we have kept the box RFI sealed adequately, at least for lower frequency RFI, so we just separated our silver wires from each other, (that is why they are not neatly bundled together) to keep the Xtalk at a minimum.
All in all, we never had any complaints from our customers or ourselves, only PMA. Go figure! '-)
Attachments
Last edited:
Outer limits: Talky Tina, orig Chucky; Shatner w pig on the wing; Evil mental kid; ...
BatMan: Egads ... Exploding cake! ...
Spiderman: Metal Monster (eats metal); Spider and the fly; Scorpion!; ...
Orig Trek: Gorn!; Horta (he loved how the baby Hortas ended up HELPING the human miners!);
Do you have:
Attachments
Last edited:
No, but did you know Jim Williams had an original John Harrison (today's Google feature) clock.
One page says it all:
Orig Alien and The Savanah!
I am making muliple pages into posters!
Get it!
Last edited:
- Status
- Not open for further replies.