Ripping vinyl
Printed From: Graham Slee Hifi System Components
Category: Digital Audio
Forum Name: CD, DVD Audio, DACs, ADCs and Digitizing
Forum Description: The existing (and obsolete?) digital formats
URL: https://www.hifisystemcomponents.com/forum/forum_posts.asp?TID=2769
Printed Date: 27 Mar 2026 at 12:35am
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com
Topic: Ripping vinyl
Posted By: ICL1P
Subject: Ripping vinyl
Date Posted: 12 Jan 2016 at 8:27pm
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I'd never ripped from vinyl and quite fancied having a go so that I could listen to my vinyl in the car. After a small amount of research and a short email conversation with Bob (morris minor) I purchased a USB device (Behringer U-Contro UCA202) for a little under £20. We are a Mac household. My TT and Reflex M are in a different room from my iMac, so I'm limited by the availability of my wife's MacBook Pro. I installed the free Audacity software on the MacBook Pro, plugged in the Behringer by USB and after unplugging the Reflex from my amplifier I plugged it into the Behringer's inputs. The input volume from the Reflex was too high and I could find a way to reduce to reduce it in Audacity. So, I posted for help on the Audacity forum and quickly learned that there is, apparently, no way to vary USB input volumes on a Mac. Damn! The guy I had the forum dialogue with was so keen to help he even picked up the phone to GSP and spoke to John Cadman. He came back to say that a solution exists for me if I trade in my Reflex M for an Accession, which has variable gain. John C may still be waiting for a call from an unknown Reflex M owner. Well John, it's me, but at present I can't possibly justify the cost of the upgrade. I told Bob all about this and he kindly offered to lend me some in -10 dB line attenuators. These arrived and I tried them yesterday evening. Volume input was decreased, but probably a bit more than would be ideal. I have seen some -3 dB inline attenuators on eBay; I may try them. To date I've only recorded one side of one LP. Maybe a selection of attenuators would be needed for albums recorded at different levels. I don't know when I'll get a chance with the MacBook to record another LP, but on the first one I noted that one of the stereo channels was at a consistently lower level than the other. Is this likely to be how the album was recorded or is it indicative of a badly set up cartridge? ------------- Ifor ===== Reflex M & ACCESSION M, CuSat50, Majestic DAC, a Proprius pair. |
Replies:
Posted By: Chris Firth
Date Posted: 12 Jan 2016 at 9:24pm
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Which cartridge are you using? The level being very low on one channel may well be down to poor setup, but equally it may be due to a cartridge fault. Whenever I record vinyl I hook my Reflex M up to my Solo II headphone amp, and take the output from the headphone socket into the recorder's input. My recorder is a Tascam DR-07 MkII. This way I can prevent overloading the recorder's input, and because the recorder is a complete standalone unit there's absolutely no chance of noise contamination from a computer's USB port. |
Posted By: ICL1P
Date Posted: 12 Jan 2016 at 10:18pm
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The cartridge is G1042. The difference between the channels isn't huge. I've not noticed it when listening. ------------- Ifor ===== Reflex M & ACCESSION M, CuSat50, Majestic DAC, a Proprius pair. |
Posted By: Chris Firth
Date Posted: 12 Jan 2016 at 10:33pm
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The 1042 isn't known to have channel balance problems. It does however have a very high output - I know, 'cos I have one. The high output will in turn produce a significantly higher signal from your Reflex M. Your channel imbalance is likely to be down to a less than optimal cartridge setup. Which arm is on your deck? |
Posted By: ICL1P
Date Posted: 12 Jan 2016 at 10:48pm
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The arm is a Rega RB1000. ------------- Ifor ===== Reflex M & ACCESSION M, CuSat50, Majestic DAC, a Proprius pair. |
Posted By: tg [RIP]
Date Posted: 12 Jan 2016 at 11:00pm
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You can't change the azimuth on that readily, but you might be able to balance it up by tweaking the bias.
------------- Tony G |
Posted By: ICL1P
Date Posted: 12 Jan 2016 at 11:21pm
You're scaring me, but I'll have a go when I've checked out another couple of albums to confirm it is so. I hate tinkering with setup. ------------- Ifor ===== Reflex M & ACCESSION M, CuSat50, Majestic DAC, a Proprius pair. |
tg wrote:Posted By: marshmid
Date Posted: 13 Jan 2016 at 10:26am
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I use a program called VinylStudio by Alpinesoft on my PC. However, it is available for the Mac and you can download a trial. The trial was fully functional but, if I remember correctly, it restricted recording time. It has a .co.uk web address and a forum which is slow but still active. It author responds promptly to queries. The interface is 'old style' but works. It records, looks up track listings, splits tracks and builds up a 'collection' (album name, track names etc). It is more powerful than it looks. What is clever is that all editing is non-destructive and the original recording is not changed. In my opinion, this program is greatly under-appreciated. I tried Audacity but it is a more complex beast and doesn't do the 'cataloguing functions. ------------- Marsh ------------------- Reflex M, Solo UDLE |
Posted By: ICL1P
Date Posted: 13 Jan 2016 at 10:56am
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VinylStudio sounds interesting; I will look at it. I suspect that a better option, than attenuators, for recording level control will be to leave the Reflex plugged into my integrated amp and take the feed to the Behringer from the amp's pre out. I also like the idea of Chris' Tascam recorder, but I'm not going to spend money on one of those at present. I've also had an idea with respect to checking the channel imbalance apparently presented from the G1042 cartridge on my Manticore Mantra. I can try the same album on my Technics SL-7. If the channels appear more evenly balanced it will prove that I have a problem with the G1042 setup. ------------- Ifor ===== Reflex M & ACCESSION M, CuSat50, Majestic DAC, a Proprius pair. |
Posted By: Drewan77
Date Posted: 13 Jan 2016 at 12:06pm
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In case the issue is azimuth related, here is a 'simple' way to address that on a non-adjustable arm: A small layer of 'post-it' cut from the sticky edge, positioned centrally between cart & headshell. After aligning correctly, very gentle tightening/loosening of the mounting screws allows a slight tilt to correct this.   My original AT150ANV was great but when I replaced the stylus with an ATN150MLX, suddenly the LH channel lost its 'sparkle' regardless of playing with alignment or anti-skate bias. Azimuth correction restored it.
------------- Older than I once was, younger than I'll be ............................. Andrew |
Posted By: morris_minor
Date Posted: 13 Jan 2016 at 12:18pm
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What version of OSX are you using Ifor? I could lend you my M-Audio Transit USB interface if you're running an older version. Since getting a new Mac it doesn't work for me as they stopped producing drivers (at 10.6.8, I think), and I've just bought a Lexicon I-O 22 (which I'm hoping gives good results, though it'll be a while before I get to try recording as my main system is stored away while we have a big building project going on.) Anyway, the Transit drivers install a Preference Pane with sliders for input level (though I still had to use the attenuators sometimes, depending in which cartridge I was using, to get the level usable). It seems to me that audio interfaces without "knobs" on or drivers for your computer are not that good for recording vinyl. Had I realised, I'd have steered you away from the little Behringer device . .  Audacity may be free, but I've never really liked it, and I settled for https://twistedwave.com/ - Twisted Wave, which does all I want it to.
------------- Bob Majestic DAC/pre-amp Accession MC/Enigma, Accession MM, Reflex M, Elevator EXP, Era Gold V Solo ULDE, Novo, Lautus USB and digital, Libran balanced, CuSat50 2 x Proprius + Spatia/Spatia Links |
Posted By: ICL1P
Date Posted: 13 Jan 2016 at 12:54pm
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Andrew, thank you. What a simple, but effective solution. I'm going to have to get myself the necessaries for alignment. I used my brother-in-law's when he brought the arm down from your way. Bob, I'm on El Capitan so the M-Audio Transit won't do, but thanks for the offer. I should be OK if I use the knobs on my amp before it feeds the Behringer. I'll also have a look at Twisted Wave, which you mentioned previously. ------------- Ifor ===== Reflex M & ACCESSION M, CuSat50, Majestic DAC, a Proprius pair. |
Posted By: Fatmangolf
Date Posted: 13 Jan 2016 at 9:09pm
I'd second VinylStudio. ------------- Jon Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC. |
Posted By: Fatmangolf
Date Posted: 13 Jan 2016 at 9:09pm
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Great tip Andrew. ------------- Jon Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC. |
Posted By: ICL1P
Date Posted: 25 Jan 2016 at 8:13pm
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I tried taking the pre out feed from my integrated amp to the Behringer thingy, but to get the recording level high enough the Spendors were playing louder than ever. Is it safe to disconnect the speakers? I'm now connected up direct from the Reflex to the line in of the MacBook Pro (how good/bad is its ADC) and am trying VinylStudio, which looks really good. I've not yet played with the setup of the G1042 so I'm recording from my Technics SL-7. ------------- Ifor ===== Reflex M & ACCESSION M, CuSat50, Majestic DAC, a Proprius pair. |
Posted By: Paul H
Date Posted: 11 May 2016 at 12:11pm
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How are you getting on with this? I'm having the same input loudness problem with my own (completely different) set up. I'd be interested to know if you find a solution. ------------- ProJect 1Xpression Carbon UKX w/ Ortofon 2M Black; Arcam Alpha 7 CD player; Graham Slee Revelation M pre; Denon PMA 355UK amp; Epos K1 speakers; Blue Jeans LC-1 interconnects. Room: 2.9m x 3.1m. |
Posted By: Graham Slee
Date Posted: 11 May 2016 at 12:56pm
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Do you understand the voltage supply to computer devices and understand the implications? Analogue isn't digital. Analogue derived signals exceed 0dBfs where digitally derived signals cannot. Computer peripherals (built-in cards or external) typically run from 5V supplies. The op-amp (they always use them) on the input before the A to D runs on the 5V supply. Unless it's a rail to rail device it can only swing to 1.5V below the 5V and to 1.5V above 0V. This means it can only swing 2 volts. That 2 volts is peak to peak. Half of peak to peak is 1 volt - and r.m.s. is 0.707 times that which is 707mV. So, let's take a 3.5 mV nominal output cartridge and amplify it 120 times (like most of my designs do). We get 420mV. OK, that will fit! But will it? Remember I said "Analogue isn't digital. Analogue derived signals exceed 0dBfs where digitally derived signals cannot." Not a lot of people know this, but peak recorded level on vinyl at mid frequencies can reach +14dB - that's 5 x rated cartridge output. So the 3.5mV on peak recorded level can be as high as 17.5mV. Multiply by the phono amp's 120x gain and you have 2,100 mV ... ouch! So now we'll use a 6.5mV output Goldring 1000 series cartridge. We can get up to 3.9 volts! That is gross overload. How much attenuation do we need? 10dB? 20dB? It all depends on the cartridge output, the recorded level of the vinyl, what type of op-amp the ADC is using, and its voltage supply. Some ADCs use the computer's 12 volt supply - that will be better because it can take around 3V input, and maybe you'd need a 10dB attenuator for "hot" vinyl - or no attenuator for quieter recordings. But to get 3.9 volts down to 707mV we need 3.9/0.707 = 5.5, which in dB language is 15dB, so we may have to choose a 20dB attenuator. Wouldn't it be better if ADCs had a physical level control on their inputs? Well yes, of course! But the vast majorioty don't, and that's why I decided to fit the Accession phono stage with one. It's also buffered so it works with low impedance input ADCs too. ------------- That none should be able to park up and enjoy the view without a smartphone and the knowledge in how to use apps |
Posted By: morris_minor
Date Posted: 11 May 2016 at 1:53pm
I can thoroughly recommend a https://www.amazon.co.uk/Lexicon-IONIX-USB-Audio-Interface/dp/B001R1YLWO?ie=UTF8&*Version*=1&*entries*=0 - Lexicon IO-22 to anyone wanting an ADC (and more) with input level controls. Shown here recording some Charlie Parker from my Reflex . .  ------------- Bob Majestic DAC/pre-amp Accession MC/Enigma, Accession MM, Reflex M, Elevator EXP, Era Gold V Solo ULDE, Novo, Lautus USB and digital, Libran balanced, CuSat50 2 x Proprius + Spatia/Spatia Links |
Posted By: ICL1P
Date Posted: 11 May 2016 at 6:47pm
No, I've given up. I chatted with Bob via email and looked at the Lexicon and couple of others, but in the end decided not to do anything for the time being. I decided the most sensible solution would be to swap out my Reflex M for an Accession, but that'll have to wait a while. In my mind it's queued behind, Cyrus CD promo upgrade (going for the Xt Signature), Majestic and then a pair of Proprii. It'll take a while to get all that past my wife! ------------- Ifor ===== Reflex M & ACCESSION M, CuSat50, Majestic DAC, a Proprius pair. |
Posted By: Paul H
Date Posted: 11 May 2016 at 8:38pm
Bob, you don't happen to have any 15dB attenuators lurking in that drawer of yours, do you? :) Either that, or an Accession you don't mind selling for half it's retail value... ------------- ProJect 1Xpression Carbon UKX w/ Ortofon 2M Black; Arcam Alpha 7 CD player; Graham Slee Revelation M pre; Denon PMA 355UK amp; Epos K1 speakers; Blue Jeans LC-1 interconnects. Room: 2.9m x 3.1m. |
Posted By: Chris Firth
Date Posted: 11 May 2016 at 8:42pm
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A computer USB port will provide 5VDC power. |
Posted By: McHolmeM
Date Posted: 11 May 2016 at 8:49pm
The CD8SE looks pretty much the same as the CDXt transport so I'm sure she won't spot the difference!  My CD8SE was registered with Cyrus by the dealer many weeks ago for the upgrade (to CDi) but still waiting for it to be called off.
|
Posted By: Chris Firth
Date Posted: 11 May 2016 at 9:01pm
How are you powering the Lexicon, Bob? |
Posted By: ICL1P
Date Posted: 11 May 2016 at 9:42pm
She'll notice the switch from black to silver! I also registered mine a few weeks back with Audio-T in Swindon and am waiting to hear. ------------- Ifor ===== Reflex M & ACCESSION M, CuSat50, Majestic DAC, a Proprius pair. |
Posted By: morris_minor
Date Posted: 26 May 2016 at 4:19pm
I've just come across the http://www.alesis.com/products/view/io-hub - Alesis IO Hub . With gain controls for the two inputs and http://www.juno.co.uk/products/alesis-io-hub-2-channel-audio-interface/481453-01//?currency=GBP&flt=1&gclid=Cj0KEQjwvZq6BRC9kfq2zKfQ_94BEiQAOeUVC6iXZY8GQLZ3PBSjErnad3Y_3Geosrt2J7qyhxtmOVEaAvx68P8HAQ - only £49 it looks like it might make a good piece of kit for vinyl ripping . . . ------------- Bob Majestic DAC/pre-amp Accession MC/Enigma, Accession MM, Reflex M, Elevator EXP, Era Gold V Solo ULDE, Novo, Lautus USB and digital, Libran balanced, CuSat50 2 x Proprius + Spatia/Spatia Links |
Posted By: Chris Firth
Date Posted: 26 May 2016 at 4:27pm
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No worries Bob. I'd expect a firm like Lexicon to ship product with a PSU that's up to the job, and not just go with the generic SMPS, cheap as chips, piece of sh1t PSUs just about everyone else (GSP excluded) uses. I was astonished at the improvement in sound quality with my EMU0404 USB when I used a properly designed and extremely quiet linear PSU. |
Posted By: morris_minor
Date Posted: 26 May 2016 at 4:33pm
Well - it is a SMPS! Of what quality I don't really know. Even though I got it from Amazon UK it came with a European 2-pin plug so I'm currently using a shaver adaptor - far from ideal. My to-do list (which gets longer by the day) does have this as something to address . . . ------------- Bob Majestic DAC/pre-amp Accession MC/Enigma, Accession MM, Reflex M, Elevator EXP, Era Gold V Solo ULDE, Novo, Lautus USB and digital, Libran balanced, CuSat50 2 x Proprius + Spatia/Spatia Links |
Posted By: Chris Firth
Date Posted: 26 May 2016 at 6:53pm
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It might be something to address. Something like an SBooster filter would tell you whether it's worthwhile or not. They suppress the HF noise coming from your common old garden SMPS, and it might make an audible difference. I've heard them make a difference on Squeezebox Touch players powered by the original wall wart SMPS. Unfiltered they're not so good, with filter they're a lot more listenable. Using a decent linear PSU gives further gains. And it's the same with my EMU0404 USB. Use SBooster with an SMPS and things improve, use a decent linear PSU and there's an immediately noticeable lack of white noise hash. It's the PSU thing that has led to me going over to a battery powered digital recorder (Tascam DR-07). There's no PSU hash to contend with. |
Posted By: morris_minor
Date Posted: 26 May 2016 at 6:59pm
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Thanks Chris - I'll look into SBooster . . ------------- Bob Majestic DAC/pre-amp Accession MC/Enigma, Accession MM, Reflex M, Elevator EXP, Era Gold V Solo ULDE, Novo, Lautus USB and digital, Libran balanced, CuSat50 2 x Proprius + Spatia/Spatia Links |
Posted By: Chris Firth
Date Posted: 26 May 2016 at 8:56pm
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You could also look at the https://new.andertons.co.uk/p/PSA230/power-supplies/boss-psa-230es-power-supply-for-boss-compact-pedals - Boss power supplies - although SMPS they're very well made, and the nasties are filtered out. You do have the issue of the plug polarity being the opposite of everything else, but that's something easily got around. |
Posted By: Paul H
Date Posted: 28 May 2016 at 8:11am
What's the Tascam like, Chris? I'm currently using an Asus Xonar U7 soundcard for high res needledropping into a laptop but, while it works fine, it's temperamental. And I'm not utterly convinced that the use of USB 2 inputs is the cleanest way of getting a signal into the digital domain. ------------- ProJect 1Xpression Carbon UKX w/ Ortofon 2M Black; Arcam Alpha 7 CD player; Graham Slee Revelation M pre; Denon PMA 355UK amp; Epos K1 speakers; Blue Jeans LC-1 interconnects. Room: 2.9m x 3.1m. |
Posted By: Chris Firth
Date Posted: 28 May 2016 at 12:24pm
The Tascam just does what it says on the tin. The ADCs are more than good enough, as you'd expect from a company that has been active in making recording equipment for awhat seems like forever. Like any menu driven piece of kit you need to dig around a little bit to find which settings you need, but once found and adjusted it's by far the easiest and most reliable method I've used. And the noise floor of the recordings is very, very low. The eternal issues of recording LP records that many folk encounter still exist, no matter which piece of kit you use, and it's the same with the Tascam. Frequently the line level signal is too hot for the recorder/interface input, which is the reason why Graham put the variable output on the Accession phono preamp. Going direct from the phono preamp will give the simplest path. I thought about the overloading issue for a good while, and I have ended up connecting up my Reflex M phono pre to my Solo II headphone amp, and use the level control for the headohone output to keep recording levels low enough so as not to clip the recorder input. OK, so it's not as simple as phono pre to recorder input, but the Solo II is a very good amplifier, and transparent to boot.
I've used all sorts of sound cards over the years, followed by a couple of recording interfaces (Emu0202 USB, followed by an Emu0404 USB). The best of the them by far was the Emu0404, which requires its own power supply. The 0404 USB can perform ADC/DAC duties on its own without needing to have a computer connected by USB, and it has SPDIF inputs and outputs too, so it's quite a powerful and well considered piece of hardware. The Emu0404 USB I bought second hand, and it replaced the Emu0202 USB). I was immediately struck with the superior results obtained recording with it, and I attributed this to its ground planes not being connected between it and the computer over USB. It wasn't long before I wondered whether the external PSU could have beneficial effect on noise within the unit, and I tried the linear PSU I use to power my Squeezebox Touch. The lowering of audible noise floor to being undetectable told me that it was a good step - a just audible band of hiss disappeared, which has to be a good thing. The Tascam made all of that faffing about unnecessary. They don't make the model I have any more, but they still make other models which look to be functionally the same. |
Posted By: ICL1P
Date Posted: 04 Jun 2016 at 3:37pm
Apparently I am now in position 143 in the queue. ------------- Ifor ===== Reflex M & ACCESSION M, CuSat50, Majestic DAC, a Proprius pair. |
Posted By: lfc jon
Date Posted: 07 Nov 2021 at 3:59pm
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I'm thinking of starting to rip some vinyl. I have just got a Fono Mini A2D for free off a mate, He's just up graded to a Graham Slee phono amp. Now before I buy any software to do this with I thought it best to start with one of the free programs to see how I get on. I know there is one, I think I have asked this before but I just can't remember what it's called I have had a look on this forum with no luck (I think it's got city in it's name) Or maybe someone here may have a better program to use. I am not too worried about being able to play a track as in being able to skip tracks, As I would like to play a rip like a record as it was intended to be played. I will be using a laptop, Is there anything else I need other than a cable which I think I have some where or anything else I need to know. I have a weeks holiday coming up with nothing to do, so this would give me something to do other that drinking beer and listening to music (not a bad way to spend a week off) but I rather do something constructive. ------------- Reflex M, Solo (both with PSU-1) CuSat50, Lautus, Spatia & Spatia links cables. Ortofon Bronze. |
Posted By: Mikeh
Date Posted: 07 Nov 2021 at 4:48pm
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You could.try using Audacity as free software to start ripping. It will probably give all the features you need to start with. I didn't find it particularly easy to use, not very intuitive ( or not idiot proof!) and went for Vinylstudio. Not very costly and to my mind a lot easier to use. It a bit of a black hole you're stepping into, many options to try. I ended up getting an Accession MM to give the variable phono out to feed into a Focusrite A2D going to a laptop with Vinylstudio software. Works well. You need to ask Bob as the expert in these matters. ------------- Mike Technics sl1210g with Victor U-2 or Technics EPC-205C mk4 Accession MM, Majestic + Proprius, Solo ULDE Innuos Zen mini mk3 streamer Harbeth P3ESR XD paired with 2x REL t5x |
Posted By: ICL1P
Date Posted: 07 Nov 2021 at 6:16pm
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+1 for VinylStudio and +1 for ask Bob. ------------- Ifor ===== Reflex M & ACCESSION M, CuSat50, Majestic DAC, a Proprius pair. |
Posted By: lfc jon
Date Posted: 07 Nov 2021 at 6:32pm
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Mike This is what I was thinking (getting into a back hole) I'm not that good with computers. I had problems with ripping CDs (not now, I find it easy) Audacity was what I was looking for. I think my best bet is to have a try and if it don't work out I haven't lost money as I got everything for nothing. As you said Bob is the expert in these matters and if I have problems I can always PM him. (I just hope he don't get fed up with me) YES I am that bad with computers. ------------- Reflex M, Solo (both with PSU-1) CuSat50, Lautus, Spatia & Spatia links cables. Ortofon Bronze. |
Posted By: Kory
Date Posted: 22 Dec 2021 at 4:29pm
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I just posted this reply to a private request, but thought I'd share it generally on the forum. It concerned the use of the flat setting on the Accession while using software that added the RIAA curve afterwards. I tried that as well using Pure Vinyl, but found the flat setting plus added RIAA didn't give me as good of results as simply leaving in the RIAA from the Accession and foregoing adding afterwards. So I don't use the flat setting. I found the best results in just using the output from the Accession, and not worrying about trying to add the curve in the digital domain. I have been totally impressed with the rips I get though the Accession into Pure Vinyl at 24/96. What I love so much about the Accession, much, much more that the flat feature, is the second set of output jacks. So I just leave my ADC, an Apogee Duet for Mac and iPad, hooked up all the time and it's so quick to rip a record. No juggling of cables is so sweet. I leave the computer cable at the ready plugged into the Apogee and just plug it into my computer and in less than 10 seconds I'm off and running. And because of that second set of outputs, i can compare the phono to the rip while it's ripping. I can go back and forth while I'm recording by switching between Phono and Aux on my preamp. To my ears it's indistinguishable. This is possible because of those second set of outputs. This is such an unheralded feature of the Accession, but for me, it's one of its greatest attractions. It's the perfect setup for ripping vinyl. ------------- Kory Hana ML, Zu/Denon 103 Mk. II, Ortofon 2M Black, Accession MM/Elevator EXP/PSU-1 Enigma/Lautus interconnects, Apogee Duet II, SOTA Nova, CJ 17LS2, Adcom 7805, VTL MB 300 Deluxe, Infinity IRS Beta |
Posted By: BAK
Date Posted: 22 Dec 2021 at 10:23pm
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Medical electronics engineers design heart monitors to detect and amplify the small 1mV heart pulses. (Brainwaves picked up on an EEG are smaller, under 0.1mV.) They found the pulses can be more accurate with less noise by pre-amplifying the tiny signal closest to the source. The pre-amplifier is built into the pickup wires attached to the patient. The pickup pre-amp is then connected to the ECG or EKG or heart monitor by a cable up to 10 foot long (about 3 meters). Heart beat signals are EQ'd to a tight frequency bandwidth, only 1Hz to 100Hz or 10Hz to 10kHz for diagnostics... always less than 20 to 20k. Only after pre-amplifying and EQ-ing at the source are the medical signals then digitized and processed further and/or recorded. Why do they do that? Because the wanted signal is purest with less noise at the source where it is generated. (This was discovered for microphones to have a pre-amp built-in... about the same time medical did.) It makes sense to pre-amplify all small voltage signals at the source... likewise it is best to EQ those signals in the first few amplifying stages to reduce noise and phase anomalies. Medical Grade electronics are some of the most critical designs, mostly with narrower frequency bandwidths than any high quality audio system. Having myself designed and maintained most medical electronics, this process is the best to reproduce any small signals less than 0.5volts. I agree with Kory in his post above about using “EQ at the source” is best. Kory's words... "I don't use the flat setting. I found the best results in just using the output from the Accession, and not worrying about trying to add the curve in the digital domain." With digital recording, Kory likes the EQ provided by the Accession before A-to-D over the EQ done in the digital realm after A-to-D. I'm a firm believer of EQ-ing in the digital realm should be done on signals that DO NOT have an “EQ at the source” available in the 1ststages of amplification. Graham Slee's Revelation phono stage covers most EQ's needed for records as old as 1930's. Graham Slee's Accession phono stage has EQ's for 33-1/3 LP's made since 1950s. The following link has graphs and some history of many recording EQ's used: https://www.hifisystemcomponents.com/about/reproducing-old-records.html - https://www.hifisystemcomponents.com/about/reproducing-old-records.html ------------- Bruce AT-14SA, Pickering XV-15, Hana EL, Technics SL-1600MK2, Lautus, Majestic DAC, Technics SH-8055 spectrum analyzer, Eminence Beta8A custom cabs; Proprius & Reflex M or C, Enjoy Life your way! |
Posted By: Kory
Date Posted: 22 Dec 2021 at 10:58pm
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Bruce, It's always comforting to find out there is actual science that backs up what I thought I was hearing. It's like finding out I'm not crazy after all. Well, at least in one thing:) ------------- Kory Hana ML, Zu/Denon 103 Mk. II, Ortofon 2M Black, Accession MM/Elevator EXP/PSU-1 Enigma/Lautus interconnects, Apogee Duet II, SOTA Nova, CJ 17LS2, Adcom 7805, VTL MB 300 Deluxe, Infinity IRS Beta |
Posted By: morris_minor
Date Posted: 23 Dec 2021 at 11:42am
------------- Bob Majestic DAC/pre-amp Accession MC/Enigma, Accession MM, Reflex M, Elevator EXP, Era Gold V Solo ULDE, Novo, Lautus USB and digital, Libran balanced, CuSat50 2 x Proprius + Spatia/Spatia Links |