Soekris DAM1021 R2R DAC Measurements

[Blumlein 88]

I had the opportunity to play with a support cable on a TV tower (1974 or so)

Near the anchor point, were some heavy dampers; a clamp, and weights on a stub of cable (two above, two below).

We found we could whack the cable with the dampers by getting the damper weights swinging on their cable stubs.

The sound generated started at a very high frequency (short but increasing section of the cable (like 2 inches thick steel) vibrating, sort of a long yeee-ooww-oohhhhhh sound.

It was quite amusing.

Eventually we got the cable excited at a very low frequency, maybe 1 Hz, and then heard something start banging around up at the top of the tower. There was no way to stop the cable (thousands of pounds, tower height around 440 meters).

Saw the transmitter man come out of the hut looking up and scratching his head, and we left.

https://www.google.com/maps/@27.840...4!1s_4fCJn1_FvTg6n8rHh4yBQ!2e0!7i13312!8i6656

Bummer, design change, nothing to bang on the cable now. Has some kind of roller damper 100 feet up.

https://www.google.com/maps/@27.840...4!1sahqBYGmaItUq8b3XWV7EFA!2e0!7i13312!8i6656

I've tried to duplicate the effect on a guitar string, it's probably there, but it just isn't the same.

Yes I've done the same thing mountain biking on Red mountain a few years back. Some energy from puny little me input to taunt steel cables on a big transmission tower. I know the yeow sounds you are talking about.

 

[rebbiputzmaker]

From my own observation, analysis of a sweep tone creates a display with (in my humble case) virtually the same output as an actual step or impulse sound recorded by microphone.

See the Impulse and step response calculation from sweep vs actual in-air recording. https://www.audiosciencereview.com/...1-r2r-dac-measurements.2324/page-7#post-67355



In my case I played the sweep (semi steady state) , and I played the square wave and I played the impulse (transients).

The agreement of the "calculated from sine sweep" vs "recorded from real playback", surprised me.

If it's this close in the air with my little analysis toys, I see no reason for it not to be excruciatingly closer/more accurate using real tools, to look at other aspects of the input vs output.

Here is an example of something difficult to get right IMO. What do you think?

 

[rebbiputzmaker]

So much for all of that inferred knowledge and experience which after several requests to be elucidated upon has not been proffered. Somewhat telling. Courage of conviction issue??

No,but...

Don't argue with idiots, they will drag you down to their level ...... . Mark Twain.

 

[Blumlein 88]

From my own observation, analysis of a sweep tone creates a display with (in my humble case) virtually the same output as an actual step or impulse sound recorded by microphone.

See the Impulse and step response calculation from sweep vs actual in-air recording. https://www.audiosciencereview.com/...1-r2r-dac-measurements.2324/page-7#post-67355



In my case I played the sweep (semi steady state) , and I played the square wave and I played the impulse (transients).

The agreement of the "calculated from sine sweep" vs "recorded from real playback", surprised me.

If it's this close in the air with my little analysis toys, I see no reason for it not to be excruciatingly closer/more accurate using real tools, to look at other aspects of the input vs output.

Yes one of the most impressive posts ever to me. Real world sound using $100 measuring mic and free software. Slow sweep, low frequency square step and impulse all giving nigh on identical results. Yet somehow music is impulsive, and transient and steady tones mislead us. So we have math and theory on one side. The real demonstrated results on the other. Both agree. I'm left wondering where this music is special meme has left to hide from us.

 

[rebbiputzmaker]

What? I thought you knew the answer to that when you asked the question.....

Talking I think about two different things, that's ok though. Hard to have a worthwhile conversation when surrounded by the Jets.

 

[amirm]

Talking I think about two different things, that's ok though.

Think through your own question then read my tutorial on understanding audio measurements and hopefully the sun will shine on the answer.

 

[Wombat]

No,but...

Don't argue with idiots, they will drag you down to their level ...... . Mark Twain.

If I thought you/you admitted, to be an idiot I would disengage from your inputs. You do need to be more accountable with some of your statements. though.

 

[Blumlein 88]

Just to get a handle on the group thought process here.

So, the transient nature of music, the the peak rise in energy, (and the tax on power supply delivery this may cause) decay, the harmonic overtone complexity etc, can be mimicked by steady state test tones?

https://goo.gl/images/VBQFR8

Waveform of twin tone imd is one example.

 

[DonH56]

I had the opportunity to play with a support cable on a TV tower (1974 or so)

Near the anchor point, were some heavy dampers; a clamp, and weights on a stub of cable (two above, two below).

We found we could whack the cable with the dampers by getting the damper weights swinging on their cable stubs.

The sound generated started at a very high frequency (short but increasing section of the cable (like 2 inches thick steel) vibrating, sort of a long yeee-ooww-oohhhhhh sound.

It was quite amusing.

Eventually we got the cable excited at a very low frequency, maybe 1 Hz, and then heard something start banging around up at the top of the tower. There was no way to stop the cable (thousands of pounds, tower height around 440 meters).

Saw the transmitter man come out of the hut looking up and scratching his head, and we left.

https://www.google.com/maps/@27.840...4!1s_4fCJn1_FvTg6n8rHh4yBQ!2e0!7i13312!8i6656

Bummer, design change, nothing to bang on the cable now. Has some kind of roller damper 100 feet up.

https://www.google.com/maps/@27.840...4!1sahqBYGmaItUq8b3XWV7EFA!2e0!7i13312!8i6656

I've tried to duplicate the effect on a guitar string, it's probably there, but it just isn't the same.

That's cool. I used to help put up towers (mostly in the 50' to 200' range for local folk, but worked on a 2100' tower a few hours away; they had to reduce it to 1900' or something after they finished it and found it was too high for something or other -- violated some state or federal law, they had local approval). I have a fear of heights (didn't, but riding a tower down that buckled under me left permanent mental scars) but it was actually easier on that high tower as you lost all contact with the ground.

 

[March Audio]

Well yes and no. A complex waveform with many different sines making up the composite signal will mean each of those frequencies are lower in level. So the IM products will be lower in level and well mostly they'll drop below the noise floor.

As for the 24 bit noise floors well, I've yet to make any recordings that are even 20 bit. Actually I don't think I have made one at 16 bit. More common is 10-12 bits worth.

Well yes and no, that depends on the level of the different sines

We know the limitations of recordings but there are many audiophiles out there that dont and as I alluded to earlier get concerned about minutia that apparently we cant measure or that we havent even thought of yet

Audiophiles get their knickers in a twist about tiny levels of jitter for example and demand femto clocks, but we arent supposed to be worried about IM like this?

Whilst if we wished we could create a far more complex set of tones for testing, do we need to to demonstrate some equipment performs far better than others in this respect? The picture is quite clear with two tones when comparing these two dacs.

 

[DonH56]

Two signals combined with peak amplitude the same as a single tone will have IMD products higher in amplitude than the single tone's HD products. The math is straight-forward but tedious but IMD2 is about 6 dB above HD2 and IMD3 is about 9 dB above HD3 IIRC. I have the derivation in a notebook in my office.

 

[RayDunzl]

I used to help put up towers

Some makeshift crew hired by PacificTel showed up at my primitive Cell Site in Auburn California in 1984/5? to install the tower.

I remember their water cooler in the back of the beat up truck - marked "Punky Ass Death Water".

They were hanging off anything they could find to hang onto.

It's not a job I could do. Anything higher than I would jump from (at a younger age) makes me a little queasy.

 

[Jimster480]

Some makeshift crew hired by PacificTel showed up at my primitive Cell Site in Auburn California in 1984/5? to install the tower.

I remember their water cooler in the back of the beat up truck - marked "Punky Ass Death Water".

They were hanging off anything they could find to hang onto.

It's not a job I could do. Anything higher than I would jump from (at a younger age) makes me a little queasy.

I feel the same, heights aren't really for me even if I have gotten semi good at dealing with them.

 

[ampegaG]

@amirm Do I see it right, the 2nd soekris 1541 or 1421 you were supposed to receive did never arrive?

 

[amirm]

@amirm Do I see it right, the 2nd soekris 1541 or 1421 you were supposed to receive did never arrive?

The 1421 did arrive and I was hoping to keep it as a surprise until the review. I have done some preliminary testing and will publish the results soon.

 

[ampegaG]

Ok, let it run vs the SMSL-SU-8 or similar low-cost DAC pls!

 

[amirm]

Ok, let it run vs the SMSL-SU-8 or similar low-cost DAC pls!

I can do that.

 

[gvl]

I can do that.

Being both multibit, a 1441 to Yggdrasil comparison is a must-have.

 

[amirm]

Being both multibit, a 1441 to Yggdrasil comparison is a must-have.

That is the part I already did but would have liked more time with the Yggdrasil before it went back.

 

[gvl]

That is the part I already did but would have liked more time with the Yggdrasil before it went back.

You'll never have enough time with the Yggdrasil, Schiit should use this tagline.