You are here

Digitising Cassettes

For everything after the recording stage: hardware/software and how you use it.

Re: Digitising Cassettes

Postby Hugh Robjohns » Tue Sep 29, 2020 12:57 pm

Quite so, James.

Another suggestion I'd make is for the ART Cleanbox Pro which does a very tidy job of converting an unbalanced consumer output from a cassette or RIAA preamp to a balanced professional line level signal, with adjustable gain controls.
User avatar
Hugh Robjohns
Moderator
Posts: 28592
Joined: Fri Jul 25, 2003 12:00 am
Location: Worcestershire, UK
Technical Editor, Sound On Sound

Re: Digitising Cassettes

Postby ef37a » Tue Sep 29, 2020 1:07 pm

Not sure what the maximum input of the UMCs is but will check later. My UMC240HD delivered only about a volt in line output so I doubt the line in headroom was little more?

AI front controls are GAIN controls, they don't attenuate the incoming signal.

Dave.
ef37a
Jedi Poster
Posts: 12123
Joined: Mon May 29, 2006 12:00 am
Location: northampton uk

Re: Digitising Cassettes

Postby TheBev » Tue Sep 29, 2020 1:32 pm

Ah I see I should clarify a bit, I actually have an RME UCX if that makes a difference.
There are 3 different input sensitivities for the analog inputs but even at the lowest setting I still get clipping whilst recording some vinyl, and get nowhere near the -20dBfs range for all.
TheBev
Regular
Posts: 207
Joined: Mon Jun 23, 2008 12:00 am
Location: London
"The tech gets better, the user error remains the same.." Roberts Plant

Re: Digitising Cassettes

Postby James Perrett » Tue Sep 29, 2020 2:04 pm

That puts a completely different slant on things.

It might help if you gave us details of the whole signal chain as I would have thought that it would be very difficult to get anywhere near the UCX's max input of +19dBu with a domestic hifi system.
User avatar
James Perrett
Moderator
Posts: 9777
Joined: Mon Sep 10, 2001 12:00 am
Location: The wilds of Hampshire
JRP Music - Audio Mastering and Restoration. JRP Music Facebook Page

Re: Digitising Cassettes

Postby Hugh Robjohns » Tue Sep 29, 2020 2:45 pm

TheBev wrote:I actually have an RME UCX .... There are 3 different input sensitivities for the analog inputs but even at the lowest setting I still get clipping whilst recording some vinyl...

As James says, we need to know the signal chain because there aren't many consumer RIAA preamps that can push out peaks over +19dBu (which is the clipping level at the UCX's lowest sensitivity setting). A professional one could, though, on click transients at least.

RME Digital relative Levels Chart.png


This chart compares the three RME analogue sensitivity options with the SMPTE and EBU recommended alignments. As you can see, the +19 option on the RME actually matches the EBU broadcast standard (with an extra 1dB safety margin!), but I've shown it here with the SMPTE alignment level of +4dBu instead of the EBU's 0dBu since that's what most home studios operate with!

(The yellow region on each bargraph indicates the 9dB nominal programme range between the Alignment Level (green/yellow border) and the Maximum Permitted Level (yellow/red border), with the red area above showing the different systems' headroom margins.
User avatar
Hugh Robjohns
Moderator
Posts: 28592
Joined: Fri Jul 25, 2003 12:00 am
Location: Worcestershire, UK
Technical Editor, Sound On Sound

Re: Digitising Cassettes

Postby TheBev » Tue Sep 29, 2020 3:03 pm

James Perrett wrote:That puts a completely different slant on things.

It might help if you gave us details of the whole signal chain as I would have thought that it would be very difficult to get anywhere near the UCX's max input of +19dBu with a domestic hifi system.

Ok, a simple set up:

A 90's Rega Planar 3 with a Rega Exact cartridge into a Trichord Dino Mk II phono stage straight into the UCX.

The turntable set up does seem to output hot to me, the tape decks were actually 100% fine... when they were used properly, however I did not always use them properly.
The phono stage has dip switches which I believe I've set correctly but can't remember the settings off hand and I'm at work at the mo.
TheBev
Regular
Posts: 207
Joined: Mon Jun 23, 2008 12:00 am
Location: London
"The tech gets better, the user error remains the same.." Roberts Plant

Re: Digitising Cassettes

Postby Hugh Robjohns » Tue Sep 29, 2020 3:29 pm

TheBev wrote:The phono stage has dip switches which I believe I've set correctly but can't remember the settings off hand and I'm at work at the mo.

It's a high-output MM cartridge, so the RIAA preamp gain switches (DIP 3&4) should all be set to the off position to provide its minimal gain (48dB in this case).

(DIP 1&2 should also both be set to off for the standard MM impedance settings of 100pF/47k Ohms.)

However, by my calculation that preamp is providing about 15dB more gain than you really need for a high-output MM pickup like the Exact. Or put another way... you'd be a lot better off with a low output MM or even an MC pickup if you want to stick with that preamp. Assuming the preamp itself isn't clipping, with that much gain it would most definitely be capable of overloading the RME at it's minimum sensitivity. So an output attenuator between preamp and RME might be a very good idea!
User avatar
Hugh Robjohns
Moderator
Posts: 28592
Joined: Fri Jul 25, 2003 12:00 am
Location: Worcestershire, UK
Technical Editor, Sound On Sound

Re: Digitising Cassettes

Postby TheBev » Tue Sep 29, 2020 4:18 pm

Ah, that's good to know Hugh so thank you for looking into it, and there was me thinking I'd exposed yet another of my many schoolboy errors. :D

Previously I was happy with the phono stage tbh but then it ran through a 90's Hi-Fi and JPW Sonata speakers, since a rethink and a necessary downsize it's been running into a Grace M903 and on to Neumann KH80 monitors, frankly I find it a fatiguing listen, I guess that explains why.
I'd been thinking of moving the Dino on so this may give me the push.

Edit...
It sounds like I've set the dip switches correctly, all off and over to the left.
TheBev
Regular
Posts: 207
Joined: Mon Jun 23, 2008 12:00 am
Location: London
"The tech gets better, the user error remains the same.." Roberts Plant

Re: Digitising Cassettes

Postby Hugh Robjohns » Tue Sep 29, 2020 4:32 pm

48dB in an RIAA preamp is quite a lot in these days of high-output cartridges. The gain range for most modern RIAA preamps is typically around +25 to +35dB for MM cartridges, and +45 to +55 for MC pickups (some go up to +60dB or more for low-output MCs)... so at 48dB minimum, your current preamp is always going to be loud, and extra LOUD with a high-output MM pickup!

So, I wouldn't be surprised if your current pickup is challenging the internal headroom of the preamp and thus it might well be worthwhile looking for a different pickup with much lower sensitivity. Or a different RIAA preamp.

It might even be worth talking to the (British boutique) manufacturer to see if it's practical to modify it for a lower overall gain.
User avatar
Hugh Robjohns
Moderator
Posts: 28592
Joined: Fri Jul 25, 2003 12:00 am
Location: Worcestershire, UK
Technical Editor, Sound On Sound

Re: Digitising Cassettes

Postby TheBev » Tue Sep 29, 2020 7:15 pm

Thanks again Hugh / all, quite a lot to chew on there.
Initial looks at a Graham Slee phono stage seems to show that that outputs at 41.5db, Regas own models would be an obvious choice but if they publish specs they are not obvious to find. I guess I'll see what else I can turn up and maybe contact Trichord to see if it's do-able / economically worthwhile to lower the gain.
Thanks again.
TheBev
Regular
Posts: 207
Joined: Mon Jun 23, 2008 12:00 am
Location: London
"The tech gets better, the user error remains the same.." Roberts Plant

Re: Digitising Cassettes

Postby ef37a » Wed Sep 30, 2020 10:02 pm

Ooo! That's a hot lill cartridge at around 7mV. When I was dabbling with hi fi "trackability" was the buzz word and the Sure V15xxx was the king of the trackers and had an output of around 3mV when amplifiers were designed around outputs of 5mV.

The audio nut....I mean ENTHUSIASTS! Would also not countenance anything that did not track at one gram, maybe a mg above. The closest I ever got was the M75ED.

Dave.
ef37a
Jedi Poster
Posts: 12123
Joined: Mon May 29, 2006 12:00 am
Location: northampton uk

Re: Digitising Cassettes

Postby TheBev » Thu Oct 01, 2020 11:05 am

I've actually got an Audio Technica AT150sa lying around somewhere which someone gifted me, that appears to output at 4 mV. I've no idea of the math but that seems like it might be a better partner for the phono stage.
I found it a little light in the bass when I tried it so went back to the Exact, think I may need to revisit it.
TheBev
Regular
Posts: 207
Joined: Mon Jun 23, 2008 12:00 am
Location: London
"The tech gets better, the user error remains the same.." Roberts Plant

Re: Digitising Cassettes

Postby Tim Gillett » Thu Oct 01, 2020 11:54 am

I'm no expert on this but it seems strange that a modern preamp with phono inputs and level switching for modern MM cartridges would risk clipping. What am I missing?
Tim Gillett
Frequent Poster (Level2)
Posts: 2227
Joined: Wed Jan 30, 2013 1:00 am
Location: Perth, Western Australia

Re: Digitising Cassettes

Postby Urthlupe » Mon Oct 05, 2020 5:20 pm

Tim Gillett wrote:What am I missing?

Oooooooooo, I’m so tempted......

:crazy:

Loopy xx
User avatar
Urthlupe
Frequent Poster
Posts: 524
Joined: Fri Sep 20, 2002 12:00 am
Location: West Midlands/Pembrokeshire UK

Previous