Thanks for the JASA paper George.
But the article I remember has a pic of the band and also the special swinging 'doors' which were Olson's acoustical filter. Response curve of said acoustical filter too.
Perhaps the important point raised by Guru Wurcer is that we should be looking for why this happens with mikes & speakers. And it could be the EVIL OPAs, BJTs & tubes used in the EVIL amplifiers too.
I could explain my 1970s/80s test cos they used records & mastertapes we cadged of the big record companies. These had significant ultrasonic content.
But the 21st century tests with digital stuff is already bandlimited.
Hans, have you got a link to the Dutch radio tests? I'm still interested in how they conducted their test.
Records, however, can have a specific type of cutting filter known as an 'acceleration limiter', which effectively hard limits slew rate of programme material for the sake of the cutting head.
It's not the same as hard hf roll-off, because, in a sine sweep for example, peak slew rate depends on level as well as frequency.
LD
Though on very small scale Vinyls are coming back here (India). cutting (mastering (if any required?), pressing is done abroad (Probably in some European countries).
Any details about recent modern vinyl cutting process ? Will High resolution (More then red book audio CD specs) digital recording have any advantages with respect to vinyl pressings quality ?
Thanks and regards.
Any details about recent modern vinyl cutting process ? Will High resolution (More then red book audio CD specs) digital recording have any advantages with respect to vinyl pressings quality ?
Thanks and regards.
Here's an extract from 1974 from a Neumann manual concerning operation of an acceleration limiter.
LD
LD
Vinyl playback has built in slew limits as evidenced by the Holman summary of the SHURE data.
But slew limit is NOT the same as a brickwall filter.
There was an excellent paper by one of Otala's students at AES Hamburg 1981, which showed his zillion V/us slews NEVER occured with vinyl. But the paper also showed significant ultrasonic content especially with MC cartridges.
30ips mastertapes have even more.
IM 20th century O, this explained most of the bandwidth limitation test results of the previous Millenium including mine ... but it doesn't explain the 21st century DBLT results with band limited digital material.
Last edited:
On a more practical matter, as I will need to rewire my kenwood (cable snipped off when it was removed from its last home), why are SME DIN connectors so darned expensive? Best I have found is £19.
For those want to play with cartridge damping and don't own a brushed shure then you can still get the townend paddle assembly (for a price) Townshend Audio Double Outrigger and Paddle
Still have to make the trough though...
Still have to make the trough though...
Well, that Shure data is for trackability limit versus f, which I suppose is a sort of hard limiter.
Indeed, slew rate/acceleration limiters are not the same as brickwall filters. Rather, they are a peculiar type of non-linear filter that does not have a 1:1 mapping to f response, being dependant upon level.
Looking at sine f response at a single level gives a one dimensional view of a 3 dimensional world in audio.
In vinyl playback, let's say there is a 600G acceleration limit, beyond which playback mistracking occurs and/or cutting is intentionally limited by restricting curvature. Then there is a 'hard limit' to programme level slew rate. Let's say we look at an 8cm spindle radius (inner groove) at 33.33rpm, to see at what level sine programme material would be hard limited ?
We have to take into account RIAA emphasis, and look at physical peak groove curvature corresponding to 600G, for arbitrary sake.
Then the curve attached shows the profound limit on programme level versus frequency for these conditions: above this level, programme material such as sine f sweep isn't permitted. Profound, eh ? So a programme sine tone at -12dB (5.6cm/s@1kHz=0dB ) can't exist, given these rules, for example..........
This is very different from the digital world. But is just a different form of hard limiter.
Interesting ?
LD
Attachments
Or £3995 for this one Nordost Valhalla 2 Reference Tonearm Cable . Stupid, but clearly some idiot pays more for the tonearm wire than my entire equipment spend over the last 30 years!
I mean a -12dB programme level sine tone at 10kHz can't exist under these rules. This is because peak acceleration would exceed 600G, so either would mistrack if cut, or would be limited in cutting so as not to be a sine wave and thus avoid the peak acceleration.
This effect applies at perhaps surprisingly low levels of programme material at hf, and is aggravated by RIAA emphasis. However, in normal programme material, a 1/f level contour naturally applies which mitigates to an extent.
LD
The good news is that the shareholder is laughing all the way to the bank.
But wow, I see that you have missed their Odin 2 Supreme Reference tone arm cable, costing $11,999,- which is a real steal
Odin 2 Supreme Reference | Tonearm Cable
Hans
I did. Wow is their some re-writing of Maxwell going on there! Van Damme pro-patch for me (as part of some new shelving completely recabling everything).
@LD: did you get my last email about 4 weeks ago?
@LD: did you get my last email about 4 weeks ago?
Hi Bill, yes thank you I read it some time back and was set to reply but it had disappeared from my inbox. IIRC, personally I'm fine for people to take the sketches of Aurak topology and develop them. The topology of the 1st stage, which I think is the cute bit, was already disclosed in a lapsed 1981 patent when I did a search on it a few years back. I think the balanced version is a great example, and look forward to checking it out in the flesh/silicon, and thank you for your work on this, along with all those on the thread who have developed it.
My workshop is up and running, thanks, and it's great to be doing hands on stuff again. Until last week I was in a panic because I could not find a box with all my test records.......then it turned up safely in storage - phew ! I had fun fixing my scope, for which one needs a 2nd scope of course, but that's now done. The first project was repair/restoration of an Ampeg SVT 300W 6 x 6550 valve bass amp. If nothing else it tested the bench's weight bearing, it's a brute at about 40kg! And finding a dummy load up to testing it was fun !
LD
I'll re-send the bit about cantilevers and Frankenstein ortofons. Interested in your thoughts on that but getting custom stylii setups is a bit off topic.
@Hans. Started putting the shopping list together for the parts I need for the modified differential input and have a couple of questions on your SIM. Would it be OK if I PM'd you on those?
@Hans. Started putting the shopping list together for the parts I need for the modified differential input and have a couple of questions on your SIM. Would it be OK if I PM'd you on those?
Thank you. Will be another day or two as I want a chance to work it out for myself but time is not on my side at the moment!
Thanks, Bill - actually I think custom cantilevers/suspension combinations is bang on topic, because how cantilever mechanics really works is at issue, and at stake is high acceleration trackability. And, IMO, (elusive) mechanical resonant behaviour provides probably the best clues. Frankencartridge seems fair game to me, and very achievable given construction of Ortofon cantilever/suspensions, for example. I'd like to see/try a high end cantilever in a Serato suspension, for example. That might be as good as it gets, all round, perhaps ?!
LD
well certainly worth the test. I will ask about options (I think only sapphire) so if you think any of the other OM series cantilevers are up to the job let me know.