Transformers
- Thread starter chessrock
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Flatpicker
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LOL!crazydoc said:
Sad, but true!
So, if what you say is correct... then in terms of capturing as much of the input (data, sample rate, accuracy, or whatever you want to call it) analog (tape) is better than digital.chessrock said:
ADDED: And when you say dynamic range... are you talking about the freq range? If so, I think you might be right, but I'm not sure.... can anyone help us with this? I think tape has more headroom than digital... what do you think?
Before we look at tubes vs transistors/IC's and soild state vs transformers, I'd like to get a better grip on the media. Thanks
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DJL said:
No. A lot depends on what kind of sampling rate you're talking about, but for the most part, if you want to accurately capture extreme high frequencies, analog is tough to beat -- if it weren't for the fact that a lot of the extreme high frequencies will be masked by tape hiss.
No. Dynamic range is the difference between the loudest signal and softest signal and so on. And with the advent of 24-bit digital, it's not even a fair contest. Generally speaking and I mean very generally speaking, okay -- the noise floor you get with most analog mediums limits it's dynamic range.
Again, you're kind of making a blanket assumption, there.
It depends. For the most part, though, it's not the headroom that differs . . . it's the way it reacts once it's headroom is exceeded. It's true that once tape reaches it's limits, it "clips" in a much more musically pleasing manner -- i.e. by gently distorting and saturating. On the flip side, the dynamic range and noise floor of most digital recording mediums tends to be so good that you shouldn't have to ever record so hot as to make clipping a danger in the first place.Why? Not only is it completely off-topic . . . but it's been beaten to death about a million times over on every internet chatroom for the past 10 years. It's kind of like the "Who's better -- Joe Satriani or Stevie Ray Vaughan" argument.
Give it up. There will never be any definitive answers to the argument.It’s my understanding that an audio transformer couples the input and output of two devices magnetically without a direct connection. So if my understanding is correct… if an audio transformer is used as the coupling device between the preamplifier and microphone, is it still subject to all those variables even if the microphone impedance matches or is higher than the primary winding of the transformer? Also transformer coupling on say a mixer means no ground loops… right?Geoff_T said:Hi
You have to step back and look at the big picture when discussing transformers.
If you look at the output from the device the transformer sees (besides the components of the load) the resistance, capacitance and inductance of the cable. This depends on the length and nature of the cable. As an example, if there was a lot of capacitance in the cable it would resonate with the transformer and shift the frequency response... usually causing a rise in HF response above 20KHz that adds sibilance to frequency lower down.
If you look at the input to the device it's sort of the other way around. How does the transformer and it's inductance, capacitance and resistance (impedance factors) affect the device driving it? How does the cable characteristic affect the device driving it? And finally, how do these parameters affect the transformer.
In the old days... which, sadly, I can remember... circuits were based on telephone practice and were 600 ohm working. That's both an output and input impedance of 600 ohms... where maximum power transfer took place... but, except for ancient tube compressors, we use the alternative low to high impedance matching.
So, the output impedance of a device has to be very low (usually below 100 ohms) and the input impedance of the next stage is usually very high (usually above 10Kohms). The output impedance of the previous stage adequately damps the primary of the next stage, and the primary does not excessively load the output of the previous stage.
Generally the output impedance of the driving stage should never rise above 50% of the input impedance of the following stage.
Of course, transformer are wound for custom applications so they might have a 1200 ohm impedance for a mic and a 47Kohm impedance for a DI.
As for how it sounds... all those variables I discussed will affect the sound on top of what effect the transformer has. Speaking from a vintage Neve viewpoint, I doubt that any clipping is the transformer but it could be distortion from the following circuitry and a grossly overloaded amplifier input stage would reflect back strange things to the secondary of the transformer.
Thanks chessrock... hey have you ever used a signal generator to see how high of a freq tape can capture and then used a scope to see how of high of a freq can be reproduced from the tape? Also, have you ever done the same for a digital recording? Thanks again for your help.
Or has anyone here done this... and if so, what was the results? Thanks
Or has anyone here done this... and if so, what was the results? Thanks
DJL said:
Hi
Yup, magnetic coupling and bonus gain/loss if you joggle the turns ratio...
Yup, all the impedances will mess with both the transformer and the device driving it...
Not nice to match higher impedance source into lower impedance transformer though, because the neither the mic or the transformer will be the happiest of Hectors... you won't get the output you expect out of the mic and the transformer won't behave as well as it would well damped t'other way around.
Yes indeedy, audio floats from ground so no loops. Even if driven by a grounded, unbalanced, signal, the transformer will treat it as quazi balanced because there's no ground connection other than at the source.
Geoff
Oh ok oops, I had it backwards, so the input inpedance should match or be lower than the transformer inpedance... thanks again. Now, I'm back to soaking all this great help in again. And I'm sure I'll need more help. Thanks again.Geoff_T said:Hi
Yup, magnetic coupling and bonus gain/loss if you joggle the turns ratio...
Yup, all the impedances will mess with both the transformer and the device driving it...
Not nice to match higher impedance source into lower impedance transformer though, because the neither the mic or the transformer will be the happiest of Hectors... you won't get the output you expect out of the mic and the transformer won't behave as well as it would well damped t'other way around.
Yes indeedy, audio floats from ground so no loops. Even if driven by a grounded, unbalanced, signal, the transformer will treat it as quazi balanced because there's no ground connection other than at the source.
Geoff
regebro
Insane Genious!
Yes, and loads of homerecorders today record their guitars via the all-digital Guitar Pod. So, if tubes are better than transistors and analog sound better than digital, then how come guitarists like the Pod?DJL said:
Guitarists like tube amps better because
1. The distortion is different, and with guitar amps, it's all about distortion. It's NOT about getting a clean ideal sound, it's ABOUT mangling it. And you gotta do it the right way.
2. Most guitarists are extremely conservative. The ultimate orgasm is to play something like a original 1962 guitar on an original 1962 amp, and so on.
It doesn't. Different formats have different limitations. Tape has several unlinearities and noise. Digital has quantization. The effects of these limitations sound different. So you can't say that tape has a specific samplerate.
Well, the noise level of tape can be roughly compared to the bit depth or digital, and the start of the frequency roloff can be roughly compared with the sampling frequency. And in that case, the high-end tape is roughly equivalent to 48khz 20 bit sampling. So, as you see, on a straight through comparison like that, 24/96 sampling kicks tapes whiney little ass. But still many people think tape sound better. Can we say they are wrong? Nope. It's just a matter of taste. Recording electronics has long ago become so good that it's no longer a matter of who is more accurate. It's about taste.
DJL said:
Yea, DJL. I do this kind of shit all freakin' day long.
Just for my sheer amuzement.
The interesting thing about how digital sampling works at very high frequencies isn't so much in how high it can go . . . it's mainly in it's very nature of how the wave is going to be represented. It's kind of like playing a connect-the-dots game as opposed to making a smooth, fluid drawing of a wave. I don't know if it's nearly as much of an issue as people make it out to be, though.
DJL said:
Hi
You'll never get a transformer with the kind of impedance you need... at least 1Mohm (in my humble opinion... others differ).... so an active box with a high impedance is best.
The less loading you can put on your pick ups the more artifacts of the signal will you hear!
DJL said:
Hi
I never cease to be amazed at how digital has chosen to measure the parameters of performance in a totally different way to analogue.
Any Neve console at 80dB gain has an EIN of at least 125dB. Most can well exceed +26dBu so tend to swing up to around +28dBu.
That's real, take it to the bank, dynamic range of 125 + 28 = 153dB.
The problem with digital is that, like power amps, they measure noise from the maximum output down... rather than referencing it to 0dBu.
The effect is that you get some unbelievable specs on paper, but if you stick your ear close to the monitor loudspeaker... that ain't the same degree of noise that you'd expect from that magic number.
c7sus
Disenfranchised Member
I thought Nyquist's Law determines the frequency response of digital media. He claims that the highest freqency is half the sampling rate. So theoretically the frequency range of 196K sample rate is 0-98Khz. Nyquist's Law has a lot to do with why RedBook is 44.1K. Half that is 22.05KHz, pretty much the limits of human hearing. can we hear subtones of higher frequencies? Fletcher has an article about a bad module ringing at something like 60K that was detected by Geoff Emerick because it just didn't sound right.
As far as dynamic range, my GUESS is that digital theoretically has the potential for much greater dynamic range than any known analog media.
Unfortunately most producers don't bother to use it.
As far as dynamic range, my GUESS is that digital theoretically has the potential for much greater dynamic range than any known analog media.
Unfortunately most producers don't bother to use it.
Thanks again Geoff... hey I was trying to find one of my old TapeOp mags, but I can't find it... anyway, I remember your preamps employed Jenson transformers but I can't remember if the preamp was solid state or tube? Also, have you ever tried winding your own transformers? Thanks
c7sus said:
Hi
There's been a lot of smoke blown around about the ability to hear greater than 20KHz signals but the facts are more basic than that.
You may not be able to hear those high frequencies but you can hear the effect they have on lower order frequencies.
One of the most common mistake of Neve fixers/modders/cloners is the topic of output termination and the last of the 80 and 53 series era consoles all had to be terminated 600 ohms.
What happens is that the modules are stuck in lunch boxes or the patchbays are replaced and they leave off the terminating resistors.
The effect is a 10dB boost up around 35KHz or so.
You can't hear 35KHz but you can sure as Hell hear the sibilance on the lower frequencies. The modules sound overbright.
Most Neve consoles are flat at 20KHz and around -3dB at 50Khz. Just cos' it's analogue doesn't mean that it can't handle high frequencies.
Oops, then I got your preamp confused with someone elses... sorry about that.Geoff_T said:Hi
Not us.. I've not used a Jensen for any of my products ever.
Not that they are bad transformers... I'm just fussy about who makes them and keep it a closely guarded secret. It isn't Carnhill either!
Anyway, I'm a bassist and I play through my Ampeg SVT Classic and SVT-2PRO into Ampeg SVT-810E's... but, I also use a pair of Ampeg B100R's when playing small clubs... my basses are the Fender American P-Bass and J-Bass, I also have a Rick 4003. Anyway, my question is... when using my pair of Ampeg B100R's I've been feeding the amps with a splitter box (bass to splitter to each amp) is this loading down my bass and if so what's the best way to feed both amps? The Ampeg B100R's have line-outs, but they are post EQ, and I don't really like feeding one amp to the other with the line-out.
Also, I've been using the Avalon Design U5 DI when recording and I love it... but I've been thinking about trying something else lately... does your preamp have an instrument input... and if so, does it kickass on bass? I'm stuck at work in the office right now and dicking around... please post a link to your preamp. Thanks again.
c7sus
Disenfranchised Member
I understand about analogue being able to handle just about anything you want to throw at it. I was more trying to address the issue of frequency response and dynamic range in digital media, which I must add, I'm not an expert on by any measure!
Hey, Earthworks claims their pres are ruler flat from 2Hz to 200KHz!
Got any idea what the frequency of an atomic clock is? Just curious if you know how often they "sample" the radiation.
Or is it just calibrated and used at the half-life of the element????
Hey, Earthworks claims their pres are ruler flat from 2Hz to 200KHz!
Got any idea what the frequency of an atomic clock is? Just curious if you know how often they "sample" the radiation.
Or is it just calibrated and used at the half-life of the element????