What is on your workbench right now?

[Hipocrates]

Honest question, why is the schematic so cryptic?
I guess one can make a unity gain converter with the usual opamps, and usual capacitor values, and go from there.
But if schematics convey meaning is hard to me to understand this one, or is a kind of a riddle.

 

[Sokel]

Honest question, why is the schematic so cryptic?
I guess one can make a unity gain converter with the usual opamps, and usual capacitor values, and go from there.
But if schematics convey meaning is hard to me to understand this one, or is a kind of a riddle.

I believe it's this pre-amp which seems really nice:

ULTIM2 preamplifier

 

[Hipocrates]

I believe it's this pre-amp which seems really nice:

Indeed!

 

[Sokel]

That's the finalized V1.03, this time at the proper side of the PCB, etc. , KTB as generator this time :





It's kind of decent for simple, single op-amp (LME49720 here) but we don't expect miracles.
It can't drive long cables without losses as is for example, you can see a -1.2dB gain penalty already driving 6 meters cable to ADC ( I have set it up for 4dB gain for the test) and couple of dB elevated noise low.
No problem up to couple of meters though.

 

[AnalogSteph]

It can't drive long cables without losses as is for example, you can see a -1.2dB gain penalty already driving 6 meters cable to ADC ( I have set it up for 4dB gain for the test) and couple of dB elevated noise low.

It's kind of hard to speculate on that without knowing what the actual schematic looks like right now.

For starters, if the ADC is of the Cosmos ADC variety, that has more or less low input impedance (little over 600 ohms to 3k-ish depending on input sensitivity if memory serves), so if your output impedance is 100 + 100 ohms some loss would obviousy be expected. This sort of output impedance already is on the upper end of what you see in commercial designs, where it is not uncommon to sight 50-100 ohms.

Also, keep in mind that the LME49720 (LM4562) has a fairly hot but heavily degenerated BJT input stage, so if there is highish source impedance remaining anywhere, I would expect the 1/f component of input current noise density to make an appearance.

 

[Sokel]

It's kind of hard to speculate on that without knowing what the actual schematic looks like right now.

For starters, if the ADC is of the Cosmos ADC variety, that has more or less low input impedance (little over 600 ohms to 3k-ish depending on input sensitivity if memory serves), so if your output impedance is 100 + 100 ohms some loss would obviousy be expected. This sort of output impedance already is on the upper end of what you see in commercial designs, where it is not uncommon to sight 50-100 ohms.

Also, keep in mind that the LME49720 (LM4562) has a fairly hot but heavily degenerated BJT input stage, so if there is highish source impedance remaining anywhere, I would expect the 1/f component of input current noise density to make an appearance.

It's worst then Cosmos, E-MU is infamous of it.
And of course you're right about LME49720, OPA2134 which I first tested is driving it like a train, something like 0.1 dB loss.
I also expect shunting outputs to ground with some 50k-100kOhms would help.

 

[pma]

Honest question, why is the schematic so cryptic?

It is not cryptic. It is just what is already uploaded. If you know then you do not need any more.

 

[Hipocrates]

It is not cryptic. It is just what is already uploaded. If you know then you do not need any more.

Is ok, I saw that is part of your preamp, and some interesting features, I can see now that values are kind of irrelevant.
Thanks for share it.

 

[Sokel]

That's the best I could do so far (applying gain) :



Knocking down gain, even at unity, gives me another 3dB-4dB nicer noise landing at E-MU's limits at about -108dB which is a good sign.

Nicer layout, etc can maybe make it a little better but for what I need is more than enough and if I decide to make some of them I'll use way nicer components, etc, the old-DYI fashion

 

[Sokel]

Got couple of these today, via Poland:

They're so cute, they're good enough to eat

 

[Valvetubehead]

On the bench right now… Z19’s

 

[dualazmak]

On the bench right now… Z19’s
View attachment 484474View attachment 484475

Looks very nice and exciting!

BTY, are you carefully avoiding/eliminating magnetic susceptible metals (magnetizable metals) including the cable connecting terminal blocks and the screws thereof?

Spoiler

In my post #931 on my project thread, I wrote;

I once have tested “Multi-Terminal Electromagnetic Relay” and “Multi-Terminal Snap-Toggle Switch” for this purpose (i.e. switching the wires between passive and active SP modes), but I found they gave some “uncleanliness and/or distortions” to the total sound. Consequently, I believe that the “physical screw-up cabling connections” like in these SP cabling boards should be the best way to go with. I carefully and completely eliminated, therefore, any magnetic susceptible (magnetizable) metal, such as screws, Y-lugs, metal plate on terminal straps, etc. in SP high-level signal wiring; please refer to my post #4, #250 and posts #013(remote thread), #023(remote thread) and here #9(remote thread).

You would please be reminded "the typical issue case" in this regard (even with no relation at all to my project thread) happened with first version of BUCKEYE 3 Channel Purifi Amplifier in which measurable (and I think audible) distortion was caused by iron (steel) plates at the SP binding posts, then BUCKEYE quickly and nicely replaced the parts with brass plates by a kind of recall announcement; please refer to the specific thread on that amplifier, amirm’s first review pointing the issue, as well as his second preferrable review on the fixed/revised amplifier.

Furthermore, in my post #9 on a remote thread "Ferromagnetic materials in audio connectors", I also wrote as follows;
If you take a look inside some rather high-end HiFi amplifiers, you'll see that the SP output wiring (and power wiring?) uses non-magnetic terminals and screws made of brass (no iron at all) or pure copper. However, this is also a common-sense measure to prevent sound quality deterioration in HiFi amplifiers. I remember it being pointed out and explained in interviews with a Yamaha amplifier designer and a Rotel engineer. It is frustrating when working with magnetized screwdrivers (screwdrivers) because you can't catch the screws, though. Yamaha's and Rotel's amplifier designers had a hard time persuading the assembly workers at the amplifier factories, but in the end, they convinced them to use non-magnetic terminals and screws, giving priority to sound quality; I've also heard that the screwdriver, which uses a chuck to fix screws and bolts to the tip, was devised so that it could be used in factories. In my DIY audio setup, I have the same thing; I strictly/completely eliminate/avoid any magnetizable metal/screw in my SP cabling/connecting.

 

[Valvetubehead]

I need to find something for the 2.7mH big boys… trying to not use zip ties, but you know. Zip ties and non-ferrous. Just need to size a couple and get them in nylon or pp

 

[Sokel]

I need to find something for the 2.7mH big boys… trying to not use zip ties, but you know. Zip ties and non-ferrous. Just need to size a couple and get them in nylon or pp

Search at the PC customization stuff also, I have seen some crazy non-metal things for cable management/watercooling/etc , enough to hold a truck.
Can't find the site but have a search around.

And there are enormously big zip-ties as well who can stand temps, etc, look at the auto parts.

 

[dualazmak]

Hello again @Valvetubehead,

The photo quality in your above post #731 is amazingly nice!
Only if you would have no issue nor hesitant, would you please let me know the settings for your photo sessions?

I mean I would appreciate knowing your camera, lens, ISO value, focal length, aperture number, shutter speed, special lighting or not, white balance (and tuning), raw-to-jpeg and retouch software (or not), normal shooting or live-view tripod cable release shooting, auto or manual focusing, original raw and jpeg resolution (X-Y pixel size), etc.

Have you applied "focal stacking technique" using multiple photos of different focal planes (ref. here #602 through #620)?

Did you apply HDR (high dynamic range) technique for your first photo?
It looks there is no white-out saturated pixel nor black-out (blackhole) pixel in your photo; very nice!

 

[Roland68]

Hello again @Valvetubehead,

The photo quality in your above post #731 is amazingly nice!
Only if you would have no issue nor hesitant, would you please let me know the settings for your photo sessions?

I mean I would appreciate knowing your camera, lens, ISO value, focal length, aperture number, shutter speed, special lighting or not, white balance (and tuning), raw-to-jpeg and retouch software (or not), normal shooting or live-view tripod cable release shooting, auto or manual focusing, original raw and jpeg resolution (X-Y pixel size), etc.

Have you applied "focal stacking technique" using multiple photos of different focal planes (ref. here #602 through #620)?

Did you apply HDR (high dynamic range) technique for your first photo?
It looks there is no white-out saturated pixel nor black-out (blackhole) pixel in your photo; very nice!

I wouldn't be surprised if these were pictures from a smartphone. Stacking-like techniques, such as pixel shifting, have been used for several generations to optimize sharpness, color resolution, and lighting.

Most Olympus MFT cameras offer various stacking options and high-resolution shots out of the camera, no Photoshop necessary. In addition, there are affordable and very sharp lenses and powerful stabilization on every lens.

 

[Valvetubehead]

I wouldn't be surprised if these were pictures from a smartphone. Stacking-like techniques, such as pixel shifting, have been used for several generations to optimize sharpness, color resolution, and lighting.

Most Olympus MFT cameras offer various stacking options and high-resolution shots out of the camera, no Photoshop necessary. In addition, there are affordable and very sharp lenses and powerful stabilization on every lens.

We have a Bingo! Iphone13 Pro… I have been left slack jawed at native processing. Honestly, it’s so handy I can’t be without. This is from a guy who has collections of Canon and Fuji dslr and mirrorless systems. While the IPhone lenses can give up the ghost in many situations, for snapshots… jeez, it’s tough to beat.

 

[Roland68]

We have a Bingo! Iphone13 Pro… I have been left slack jawed at native processing. Honestly, it’s so handy I can’t be without. This is from a guy who has collections of Canon and Fuji dslr and mirrorless systems. While the IPhone lenses can give up the ghost in many situations, for snapshots… jeez, it’s tough to beat.View attachment 484501View attachment 484502

We have a project where we test cameras and lenses, and for Photokina 2016, we discussed smartphones vs. compact cameras/DSLRs.
Even back then, compact cameras were unnecessary in most situations, and there were only a handful of professional compact cameras that were somewhat better.
But advances in electronics and software have now become so great that compact cameras have become completely unnecessary, and the capabilities of smartphones are almost unbelievable. The low/available light capabilities are also incredibly good these days.
The same applies to the video function.

Of course, this has nothing to do with traditional creative photography.

 

[Valvetubehead]

I’m a really big fan of this led light … I’ve used some “architect” led light bars as well, but think I prefer these:

 

[Roland68]

I’m a really big fan of this led light … I’ve used some “architect” led light bars as well, but think I prefer these:
View attachment 484527
View attachment 484528
View attachment 484529View attachment 484530

When using LED lights for photography, you should look for a high CRI value. At least 95, preferably 99.
The colors in the image are only reproduced to the extent that they are present in the light spectrum. If, for example, the red component is completely missing, a tomato will remain black in the photo.