Strange my X-Rays have clearer bass freq's than my lacquers?

[powerstrip]

Hi

Not sure if anyone has experienced this before, and I will post up the difference when I get back to the lab, but I have an interesting dilemma.

I have been getting very clear bass frequencies out of MRI's I found in an old hospital. But I wonder why I can't get these solid bass lines when I am cutting lacquers? My lacquers seem to lack sub frequencies I am needing, and they distort when I crank the levels. (I assume this is due to me being a novice)

Of course the MRI's sound horrid on the high end. But the bass sounds great. The opposite holds true on my lacquer cuts.

I am cutting the lacquers with Markrob's inverse RIAA plug-in, and the MRI's were cut with no plug-in at all.

[tragwag]

the RIAA encoder would be why the bass is the better on the MRI.
are you 'cutting' both of them?
rather than 'embossing' i mean

[powerstrip]

the RIAA encoder would be why the bass is the better on the MRI.
are you 'cutting' both of them?
rather than 'embossing' i mean

yeah definitely 'cutting' the MRI's

Embossing does not seem to provide good tracking with the MRI's

I suspected as much with the RIAA curve, but when I go without RIAA filter on my lacquers, it always sounds muddy, overdriven, and distorted

[opcode66]

You could try making a custom curve. Other cutters have done this in order to achieve a more flat frequency response on material cut by their head. Har-Bal is a tool you can use to perform analyses on original source material and a recording of cut material in order to create a proper EQ Curve that will give you a flat response.

Also, I'm thinking you could probably just split the difference and go with a half RIAA EQ Curve. Split it at the zero db point... 1000 cps. Leave it flat in the low end and keep the high end emphasis. Or possibly do emphasis in the low and and flat in the high. I think you get the idea.

We aren't recording big bands with lead singers anymore. The RIAA eq curve is a little out of date.

[tragwag]

thats a great idea todd.
especially if your system is different for each material, optimize it for that material!
and good to know you're cutting both materials, just wanted to make sure your stylus use/geometry wasn't the reason for the frequency response difference.

[markrob]

Hi,

A couple of points to expand on Todd's ideas. At the end of the day you need the RIAA curve to be in place since the playback system has the mirror image of this curve. You may also need additional corrective EQ to flatten the head response. This is where Har-Bal or some other EQ tool comes into play. However, if you start with the traditional RIAA curve in place prior to any corrective EQ, you may end up doing more EQ than is needed. For example, Presto and many other moving iron heads already have the 500hz turnover in place by design. If you use a full RIAA EQ with this head you will be killing the low end by duplicating the same roll-off in the RIAA curve and have to make up for it with addtional EQ. To prevent this, I developed a second version my RIAA plugin that eliminates this turnover for use with these heads (see Todd's suggestion above). One thing to note about Har-BaL. The first gen version of this program works great within its EQ boost/cut limits. The new version has been majorly overhauled and adds a ton of features for mastering engineers, but unfortunately, renders it unusable for the functions we need. I'm not sure they will still sell you the original version anymore. So unless and until they make some changes, I would no longer purchase the current version. There are some other similar EQ/Spectral matching EQ's on the market (Voxengo comes to mind), but I have not tested them.

One of the possible reasons for the differences you are noting is that some head's frequency responses are affected by differences in the media you are cutting. So if you develop a total corrective EQ based on cutting in a particular medium, you may find that it does not apply when you change.

Finally, you might want to consider running a 2nd or 3rd order subsonic filter on your program material as the last pre-mastering step prior to cutting (limiting the extreme highs might also be in order). You could be cutting large excursions that just waste space, power, and add to distortion with no sonic benefit.

Mark

[JayDC]

mark,

what if you are using a "hardware" iriaa device in the preamp to the amp to the 1-C/D... how would you make this correction in reality, as opposed to virtually?..

[markrob]

Hi,

You would have to use an analog EQ(s) (parametric, graphic, etc.). To come up with the correction EQ you would either need to use you ears, an RTA, light band, or other method of determining frequency response.
Mark

[JayDC]

ok, cool.. i have most of these setting stored in my daw, from using your older plug-in that doesn't compensate.... now to find a tube pEQ, if they even exist..

[Stevie342000]

Jay

Try looking on this website this page may be of use there are others under schematics http://www.preservationsound.com/?p=1875 you can download the pdf and this circuit will do NAB or whatever you want it to do. I think if memory recalls the RCA curve is mentioned which I believe is the same as RIAA, hope that helps. There are some really useful circuits on here mostly from the era of many of the cutting lathes themselves.

cheers,
Steve

[JayDC]

Jay

Try looking on this website this page may be of use there are others under schematics http://www.preservationsound.com/?p=1875 you can download the pdf and this circuit will do NAB or whatever you want it to do. I think if memory recalls the RCA curve is mentioned which I believe is the same as RIAA, hope that helps. There are some really useful circuits on here mostly from the era of many of the cutting lathes themselves.

cheers,
Steve

thanks for the information, this is right up my ally... i would LOVE to setup a columbia 500C-16 curve on this gear.. this also looks pretty nice, but the price is very high: http://www.pulteceqp1a.com/

[Stevie342000]

Jay

I think you will find that the Pultec is less versatile, as you can not boost/cut or some such with the Pultec, its mentioned on the Preservation site oh and a lot cheaper as well.

That circuit can be used to both RIAA playback or RIAA inverse for recording, the same applies to other recording curves if you know which frequencies to boost or cut.

I was going to build one for my cutting lathe system, when I get it up and running.

Glad it helped, I thought it might but I was not sure.

Cheers,
Steve

[JayDC]

it does help, a lot.. mind if i ask what your cutting system is? if you want amps and preamps (all tube) you should check out tubes4hifi.com, it's a rebirth of the old dynaco stuff.. everything is super affordable for what it is, and superb quality... they keep the prices low by requiring you to assemble the kits yourself... they don't skimp on the components though, hi quality caps, 1% resistors, and custom made iron transformers for the amps.. i highly recommend them.. i'm putting together an sp12/ph12 preamp kit atm, and have 2 mono block kits sitting here waiting... can't wait to get everything setup so i can cut with it.. i have a feeling it's going to sound great.. bob and roy at VTA are very nice people and extremely helpful when it comes to tube gear... good people to know...

i'm going to approach roy about seeing if the design you pointed me to would be a candidate for a kit, i think a lot of people on the dynaco side would be interested in something like this.. and it would make it easier to get higher quality components since they would be able to order enough to keep the price low.. digikey has a minimum order quantity of 1,000-5,000 pieces for 1% resistors (I'm sure it's the same for caps too), and i know i don't need that many.. and you got to watch out on ebay, from what i here there are a lot of people selling "high quality" components that don't meet specs... :/

vta also has a nice iriaa kit as well...

great to have you around the forum steve, i don't think i've seen you around before... welcome aboard...

[Stevie342000]

Jay

Been around here for a while I have a Rek-o-Kut MS-5 overhead cutter, not functioning properly, stuck on the guide rails, needs an overhaul. A Presto 5C head and not much to cut on beyond a Garrard 401 which may not be up to it.

Looking at a new turntable Franken-cutter made of a Rega bearing & platter a valve vari speed motor drive amp, a pulley system a la Presto 6N (cone system) to drive the turntable. Oh yeah drive motor an old Ferrograph spooling motor, belt driven.

Options still open, as for cutter amps I have 3 Williamson amps which will do the job 2 for cutting one for monitoring, maybe using that to drive a Musician Senor (see Audio Engineering Anthology 2 i think) which uses a couple of transformers one for bridging and the other for output, using 845 tubes in push pull driven by the Williamson, it was designed for cutting lps by Selstead and Sprinkle (both from Ampex), should do the trick eventually with one of Flo's nice stereo cutter heads.

Still all up in the air but will check out that link, Bonvalta Audio good place for circuits go google it, nice 400 Watt KT88 amp there that should cut the heating bills nicely but not the fuel bills.

Steve

[JayDC]

Jay

Been around here for a while

Steve

I figured, but i've never seen yah

and in case anyone wants to know eq points for various curves used before 1964 check this out: http://midimagic.sgc-hosting.com/mixcurve.htm