Thanks, Bill. For sure I'll test with a standard OM body, though if at the same time it's possible to send through the superOM I'd be interested in testing that too.
Ultimately I'll spin up an OM40, and the S-120.
Tailoring to suit specific cart R and L I can do. I've lost track a bit - does the balanced version conserve the elegance of design around about a ratio of 2:1 in resistance:inductance(mH) ?
I've been enjoying the unbalanced version of Aurak for several years as my main listening pre-amp, of course. It's been solitary, a minority of one (until George built one!) but really very good too. Looking forward to sharing the experience and opening the door to flat measurements of MM/MI above the audioband.
Thanks again !
LD
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ok, I'll cover those bases. I'll contact you offine to work out how to fit the S-120 stylus to the OM body properly as I was clearly doing something wrong!
It's the same ratio for the series resistance just split equally between the two paths. Now one can argue about whether the concept of CMRR actually exists for a floating source but as it's easy enough for me to match to 0.01% I might as well.
One thing that has been bothering me is that ortofon claim 0.5mg for all their bonded tip stylii whether hifi or DJ, which suggests that the shank is the vast majority of the mass. But they also in some of the S-120 literature suggest that the FR roll off at 18kHz is there on purpose to minimise HF noise when tracking control vinyl. If this is not due to the moving mass and that is certainly not a flexy cantilever what is going on?
I'm thinking that a lower mass tip might be all that is needed? That or I haven't been paying proper attention
It's the same ratio for the series resistance just split equally between the two paths. Now one can argue about whether the concept of CMRR actually exists for a floating source but as it's easy enough for me to match to 0.01% I might as well.
One thing that has been bothering me is that ortofon claim 0.5mg for all their bonded tip stylii whether hifi or DJ, which suggests that the shank is the vast majority of the mass. But they also in some of the S-120 literature suggest that the FR roll off at 18kHz is there on purpose to minimise HF noise when tracking control vinyl. If this is not due to the moving mass and that is certainly not a flexy cantilever what is going on?
I'm thinking that a lower mass tip might be all that is needed? That or I haven't been paying proper attention
A penny just dropped. That 1963 reference to a thin carbon film made me realise that they probably were using TEM for the imaging, which would explain a lot. Walton just talks about 'electron micrographs', which of course he would as SEM was PhD research project stuff at the time.
I am off to write lines 'I must not jump to conclusions'
I am off to write lines 'I must not jump to conclusions'
- Here is another article by Mr. Barlow. Wireless World April 1964. (Page 4 of pdf page 160 of magazine)
- One more article with probably same Scans by Mr. Walton. Wireless World August 1961 (Page 17 of PDF page. 407 of magazine)
Kindly see what you all can make of it. Figures, charts and numbers makes me dizzy.
- Articles are saying there is damage (dont know how severe) on first and fifth play (there are pictures in article) but after that there is no damage and walls are smoothened.
- What are the chances of Decca SXL 2057 given RIAA Pre-emphasis ? That would give more amplitude on vinyls and scans. Isn't it ?
- I read somewhere Mr. Walton worked for 7 years in Decca Company before he started his own company. So access to Scanning Electron Microscope may be was the courtesy of Decca Company.
Regards.
- One more article with probably same Scans by Mr. Walton. Wireless World August 1961 (Page 17 of PDF page. 407 of magazine)
Kindly see what you all can make of it. Figures, charts and numbers makes me dizzy.
- Articles are saying there is damage (dont know how severe) on first and fifth play (there are pictures in article) but after that there is no damage and walls are smoothened.
- What are the chances of Decca SXL 2057 given RIAA Pre-emphasis ? That would give more amplitude on vinyls and scans. Isn't it ?
- I read somewhere Mr. Walton worked for 7 years in Decca Company before he started his own company. So access to Scanning Electron Microscope may be was the courtesy of Decca Company.
Regards.
Yes ! That would explain the references to 'flattening' and carbon film cracking at the groove base. Well done, Bill.A penny just dropped. That 1963 reference to a thin carbon film made me realise that they probably were using TEM for the imaging, which would explain a lot. Walton just talks about 'electron micrographs', which of course he would as SEM was PhD research project stuff at the time.
I am off to write lines 'I must not jump to conclusions'
Then the vertical scale would automatically be magnified by sqrt(2), as though one were looking at both surfaces from above at the same time, folded flat along the groove base line.
Also note that dimension A as drawn on Walton's own mark-up is the total swing, ie x2 modulation amplitude.
Taking these factors into account, the image tallies OK with Decca SXL 2057 - at last - so that settles that I hope. And we can be fairly sure the vertical scale is magnified by sqrt(2) versus the horizontal scale for the purpose of measurements.
The stylus radius was approx. 0.0008", from marks, which also makes some sense in about 1961.
LD
Yes, Decca SXL 2057 uses RIAA pre-emphasis for sure: I have a copy. The 10kHz band physically works out as about 4.8 cm/s rms, near enough to 5cm/s as to not worry about here.
LD
As I mentioned, by 1961 there were only 3 SEMs in the UK in total and one of those apparantly didn't work very well. The first commercial sale of an SEM wasn't until 1965. However TEM was relatively well developed by the late 50s and AEI, who were a stones throw from Salford were the biggest manufacturer of TEM in UK (possibly only). So whilst wild conjecture I think they realised they had to work with what they had and needed a thin film cast of the groove. this was the 'special technique' Dr Chippindale worked out.
I have this vision of tweed jackets and pipes being used to poke at things in true Barnes-Wallace style.
Thanks LD and Bill.
There is also another article about designing pickups for low record wear (it is about crystal pickups mind you) again with formulas. It is in Wireless World April 1959 page 182. Can these guidelines be used to pick modern pickups ? From all the article it seems high compliance, low tip mass very well damped tonearm can be ideal. Right ?
Off Topic : I hear Crystal Pickups had high output. Some Sonotone models had the highest output ever. Can a step-up transformer (like used in Moving Coil cartridge) be used to drive small highly sensitive speaker. No amplification electronics in the chain
There is also another article about designing pickups for low record wear (it is about crystal pickups mind you) again with formulas
. It is in Wireless World April 1959 page 182. Can these guidelines be used to pick modern pickups ? From all the article it seems high compliance, low tip mass very well damped tonearm can be ideal. Right ?Off Topic : I hear Crystal Pickups had high output. Some Sonotone models had the highest output ever. Can a step-up transformer (like used in Moving Coil cartridge) be used to drive small highly sensitive speaker. No amplification electronics in the chain
many MM cartridges have a 78 option these days. New ceramics are available as well. but you still need an amplifier, albeit no RIAA
I have read that 78s were popular in India until recently in some genres (schools?) and as a result there are millions out there and some collectors that are awsomely bonkers with tens of thousands of 78s of rare music.. I hope this is true
I have read that 78s were popular in India until recently in some genres (schools?) and as a result there are millions out there and some collectors that are awsomely bonkers with tens of thousands of 78s of rare music.
. I hope this is true
No. Schools didn't had any players or 78s. Atleast that I know of living in small town.
The person I mentioned in some thread may have 400/500 shellacs. Anything related to vinyls fetches good money here. I had purchased vinyls from 40 Rs. 7/8 years ago, now they sell for x 10 times. Sellers have become greedy. They demand money for even scratched vinyls. Brown and black.
Regards.
The person I mentioned in some thread may have 400/500 shellacs. Anything related to vinyls fetches good money here. I had purchased vinyls from 40 Rs. 7/8 years ago, now they sell for x 10 times. Sellers have become greedy. They demand money for even scratched vinyls. Brown and black.
Regards.
Centenary of Indian Gramophone Records suggests 78s were sold until the 70s, you could even get the beatles on 78!
This guy is a serious collector. Perfect Sound Forever: Indian record collectors
None of which helps me as I am confused trying to understand how to map velocity on a recording to um peak excusion. B&K QR2010 has a max of 24cm/s at 1KHz (or +8dB). I am stuck finding the derivation. is the 24cm/s peak velocity of distance travelled by the wiggle?
This guy is a serious collector. Perfect Sound Forever: Indian record collectors
None of which helps me as I am confused trying to understand how to map velocity on a recording to um peak excusion. B&K QR2010 has a max of 24cm/s at 1KHz (or +8dB). I am stuck finding the derivation. is the 24cm/s peak velocity of distance travelled by the wiggle?
The most I ever paid for a record was on DUM DUM (Indian EMI) for what I thought was one of only a few existing copies. About 5yr. later someone found an entire case in a warehouse somewhere in India and the price dropped to 20%.
The record is still not listed in the artist's discography at any internet source.
Hiten. I have old console stereos from the 1960s that use ceramic carts. The output is somewhere around 1/2 volt, which is more than enough voltage for a speaker. It's the impedance that's the problem. They just won't supply enough current into an 8 or 16 ohm load, as they typically were meant to be connected to 1 meg inputs.
Grado also made a low output Hi-Fi ceramic in the 1960s - it ran thru a standard RIAA preamp. I had one for awhile.
Grado also made a low output Hi-Fi ceramic in the 1960s - it ran thru a standard RIAA preamp. I had one for awhile.
Short answer: for a sine wave, peak excursion = peak velocity/ω
Peak velocity means instantaneous velocity of the stylus due to groove modulation, in a given direction.
ω = 2*pi*f, of course.
Derivation from rotational physics:
Instantaneous displacement D = peak excursion * sin(ωt)
Instantaneous velocity V = dD/dt = peak excursion * ω * cos(wt)
[hint: d(sin(ωt))/dt = ω*cos(ωt) by the chain rule]
Peak velocity [hint:when cos(ωt) = 1] = peak excursion * ω
Rearranging gives the result: peak excursion = peak velocity/ω
HTH!
LD
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Does anyone else have a problem with Mr. Eliot's conclusion that recorded levels at 20k never exceed 5mV (Audio Levels vs. Frequency)? He seems to leave off either pre-emphasis or velocity sensitivity. No comments since 1999?
Hi-Fi RIAA Phono Preamp
Hi-Fi RIAA Phono Preamp
Thank you. Google for once had failed me. I shall remember that now. So 24cm/s at 1kHz is roughtly 24/6000 or 40um. I note shure boasted the V15-V could track 60cm/s at 10kHz. Not sure how true that was, or if actually there ever was a record recorded quite that hot.
Scott: using FM radio to set RIAA overload parameters seems very very odd!
Scott: using FM radio to set RIAA overload parameters seems very very odd!
Especially since that Shure graph was around for decades. Mr Eliot removed one of his pages (condenser mic distortion) years ago, I'm sure I was not the only one to see the mistake he had voltage and current mode flipped and since there are virtually no commercial current mode mics the discussion had little use.
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http://pubs.shure.com/guide/V15VxMR/en-US.pdf
V15xMR
Trackability at 1 gram (10 mN ) Tracking Force (typical values shown in cm/sec peak velocity):
400 Hz: 30 cm/sec
1 kHz: 46 cm/sec
5 kHz: 80 cm/sec
10 kHz: 60 cm/sec
George
