Vinyl Lovers? Advice?

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Hey Guys,


Well after months of searching, I found a turntable!

I think I got a sweet deal, a very good nick Thorens 160 MKII, came with a SME Series 3 Pick-Up Arm and fitted with an Audio Technica cartridge, paid about $150USD

Thorens_160_MKII.jpg


I still have so much to learn about all this. I tested it at the previous owners house but now need to get an RIAA preamp and work on putting together an amp/speakers to listen back on.... but at least half the battle has been won!

Thanks for all the advice  ;D

Cheers

Matt



 
matta said:
Hey Guys,


Well after months of searching, I found a turntable!

I think I got a sweet deal, a very good nick Thorens 160 MKII, came with a SME Series 3 Pick-Up Arm and fitting with an Audio Technica cartridge, paid about $150USD

Cheers

Matt

Yes that does sound like a very good deal indeed!   A cartridge upgrade would be in order at some point, and make sure to check now for needle wear (some history of use for starters).

There's a lot of motion in the vinyl area these days.  I heard through the grapevine that Doug Sax is thinking of pulling his mastering lathes out of storage, and another boutique producer is starting to think of making all-tube-electronics recordings again.  I'm working on a mid-priced hybrid tube-sand-state phono preamp myself right now.





 
You got a very good deal! The SME arm alone would sell for more than that most of the time.

I suggest you buy a brand-new drive belt so you're starting clean.

Peace,
Paul
 
jackies said:
:eek:
Thats a totally pimping arm!!!


You need a degree just to understand the thing! Seriously... it is hardcore, esp. for a newb like me... back to reading the manuals... Again thanks for all your help and support in this new experience/adventure.

Freddy your mates stuff looks great and VERY good value for money.

I'm just wondering if it is worth using a valve phono pre and then solidstate or maybe worth making a simple phono pre and little value amp for this guy? Back to DIY again.... and if so... any suggestions on a DIY solution that is both affordable, but also sounds great?

Cheers

Matt

 
It's been brought to my attention that SS amp happiness now starts whith the name "LME49810"...

http://www.national.com/pf/LM/LME49810.html
http://www.national.com/pf/LM/LME49811.html
http://www.national.com/pf/LM/LME49830.html

http://www.national.com/an/AN/AN-1849.pdf
http://www.national.com/an/AN/AN-1850.pdf
 
Matt,
I've heard Ken's phono pre and I think it sounds very, very nice :)
Indeed, the price is pretty hard to beat!
Freddy
 
Even if the belt is rotted and the needle is chipped and there's a mouse-nest inside, that's a fabulous buy.

> I'm just wondering if it is worth using a valve phono pre and then solidstate or maybe worth making a simple.....

You wonder too much.

Build a Bugle. You can have it working in an hour, it is approximately as perfect as phono gets, and the investment won't crimp your long-term plans to build luscious flux-condenser preamps; meanwhile you have music to build by. While you should buy the Half-Kit, Hagerman can use the income, if shipping and taxes to SA make this silly, he's posted enough detail that I know you can stick it together locally.
 
PRR said:
Even if the belt is rotted and the needle is chipped and there's a mouse-nest inside, that's a fabulous buy.

> I'm just wondering if it is worth using a valve phono pre and then solidstate or maybe worth making a simple.....

You wonder too much.

Build a Bugle. You can have it working in an hour, it is approximately as perfect as phono gets, and the investment won't crimp your long-term plans to build luscious flux-condenser preamps; meanwhile you have music to build by. While you should by the Half-Kit, Hagerman can use the income, if shipping and taxes to SA make this silly, he's posted enough detail that I know you can stick it together locally.

Thanks PRR,

Funnily enough the Bugle was the first DIY RIAA I stumbled across in my Google search, shipping is INCLUDED worldwide and the costs seem very fair. He has now also added a linear power supply as an option as well (I may just end up building my own due to costs).

The seller actually gave me a broken, cheap RIAA preamp made by a British company called QED... very simple stuff, rebuilt it yesterday, gave it a full recap (Tans and Lytics) and replaced the 9V battery snap that was shorting out and got it back up and running, a little noisy, but allowed me to get some music out of her... more tests to follow...

Cheers

Matt
 
Tonearm set-up is important.

I had a turntable-nut friend set mine up.....or heavily research the methods  yourself. (balancing, tracking, cartridge alignment, etc...)
Chances are it may have already been tweaked properly, given the nice quality tonearm.....but wouldn't hurt to check it.
This may be fall a bit into "audiophile lore", so I am willing to hear other's thoughts.....
...but it may feel reassuring to have it "professionally" set up/checked.




=fb=
 
I am not going to deliver another point by point critique of the Bugle. Instead to be more positive, let me suggest a few criteria that I consider useful in RIAA playback.

1: good input termination.  There are lots of good modern opamps that could be used here. Select one with low distortion and high input impedance, in non-inverting topology. Terminate passively with 47k (or 47.5K) resistor and a couple hundred pF (small film).  Ideally factor in turn table and cable capacitance to provide correct cap load for given cartridge. First gain stage should probably be able to cleanly accept a few Volts, peak-peak, so keep fixed gain <20dB.

2: accurate RIAA: there is some debate about this since it isn't defined below 20Hz and above 20kHz. What is universally agreed to is time constants. Pole at 3180 uSec, zero at 318 uSec, and final pole at 75 uSec.  Note: IEC proposed an additional pole at 7980 uSec to address  infrasonic energy...  This additional LF pole will infringe on very low bass, so this is a personal choice. On the high end, I advocate providing the 75 usec pole as a real pole, so above band HF energy continues to get rolled off at -6dB/oct. 

This RIAA eq can be spread across two opamps nicely, There are many (other) published designs that do this adequately.

http://www.national.com/images/pf/LME49870/300194k5.pdf 

While I have not checked out this National app note, it looks like it meets my criteria (give or take a little- no Infrasonic filter could be problem with warped records, and I'd add some build out resistance in output).

Enjoy...

JR

 
Although I'm sure the National circuit is satisfactory, the input noise current density of the part will be a significant contribution to overall noise at the typical spec of 1.6pA/sq root Hz, in the frequency range where a moving-iron cartridge's inductance is the dominant component of impedance.

The RIAA compensation they show is accurate for ideal opamps to a peak-to-peak error of about 0.14dB between 20Hz and 20kHz.  This of course presumes that your component values are precise.  I am a bit peeved when I see circuits paralleling three caps to get a supposed value of their sum, without saying how precise the larger of the parts need(s) to be.  The best policy is to get some and measure with a good capacitance meter.

The same holds true for series and parallel combinations of resistors, but here at least you can buy 0.1% ones to begin with.

The accumulation of input offset voltage at these d.c. gains will be appreciable but perhaps tolerable.  In the rare case of where the rest of the chain is d.c. coupled you will want to have some d.c. block or correction somewhere before hitting the loudspeakers or headphones.  Worst-case d.c. offset due to voltage offset would be about 375mV.  Since the part has input bias current cancellation to a nominal 10nA and max 72nA, this will be a different contribution but not too serious for typical moving-iron cartridges (R internal usually around 1kohm).  However with the cartridge disconnected the output of the preamp could be as much as 1.8V due to this term and the 47k input R, with the d.c. gain of 535 (+54.6dB).

Overload capability is good even with the passive central EQ section.  The limitation is in the first stage output swing, which for a 20dB nominal overload at 20kHz, i.e. 500mV rms, is already 11.6V rms.  But note that the gain is actually quite low---at 1kHz one typically sees preamps around 40dB or more, and this one is about 34.7dB for that reference frequency.

The impedance of the first stage feedback network could be reduced a bit for slightly lower voltage noise---the 150 ohm R raises the nominal 1kHz noise density due to the opamp alone from 2.5nV/sq rt Hz to almost 3nV.  Of course that is still pretty low.  Also you don't want to tax the output current capability of the first stage too much.

And also as JR suggests, a little buildout R in series with the output is advised to ensure stability driving cables.

A full analysis of noise performance of preamps for moving iron cartridges is complicated, but there's a National app note with a very good discussion and example.  I don't have the ref at hand at the moment but it's been in a thread or two here.
 
Freq Band said:
...but it may feel reassuring to have it "professionally" set up/checked.

It's easier than any projects around here. You want to adjust the cartridge angle that is parallel to the plane of the record so that the stylus follows the groove radius at the outer and inner diameter. This is impossible to get perfect. You can eyeball it pretty well.

Follow manufacturers recommendations for tracking force. If in doubt use 3g.

For antiskate get a bright loud record. Listen for distortion in the right channel at the inner diameter. Assuming you have the orientation correct, adjust the anti skate until the distortion goes away or moves to the left side. You have now gone too far. Listen at the outer diameter and it will sound worse then before. Pick a happy medium.

Vertical Tracking Angle. Ignore it. There is no standard angle that a cutterhead is mounted at so there is no correct setting for vertical tracking angle. If you are doing transfers and getting payed for it it might be worth playing with.
 
bcarso said:
Although I'm sure the National circuit is satisfactory, the input noise current density of the part will be a significant contribution to overall noise at the typical spec of 1.6pA/sq root Hz, in the frequency range where a moving-iron cartridge's inductance is the dominant component of impedance.

The RIAA compensation they show is accurate for ideal opamps to a peak-to-peak error of about 0.14dB between 20Hz and 20kHz.  This of course presumes that your component values are precise.  I am a bit peeved when I see circuits paralleling three caps to get a supposed value of their sum, without saying how precise the larger of the parts need(s) to be.  The best policy is to get some and measure with a good capacitance meter.

The same holds true for series and parallel combinations of resistors, but here at least you can buy 0.1% ones to begin with.

The accumulation of input offset voltage at these d.c. gains will be appreciable but perhaps tolerable.  In the rare case of where the rest of the chain is d.c. coupled you will want to have some d.c. block or correction somewhere before hitting the loudspeakers or headphones.  Worst-case d.c. offset due to voltage offset would be about 375mV.  Since the part has input bias current cancellation to a nominal 10nA and max 72nA, this will be a different contribution but not too serious for typical moving-iron cartridges (R internal usually around 1kohm).  However with the cartridge disconnected the output of the preamp could be as much as 1.8V due to this term and the 47k input R, with the d.c. gain of 535 (+54.6dB).

Overload capability is good even with the passive central EQ section.  The limitation is in the first stage output swing, which for a 20dB nominal overload at 20kHz, i.e. 500mV rms, is already 11.6V rms.  But note that the gain is actually quite low---at 1kHz one typically sees preamps around 40dB or more, and this one is about 34.7dB for that reference frequency.

The impedance of the first stage feedback network could be reduced a bit for slightly lower voltage noise---the 150 ohm R raises the nominal 1kHz noise density due to the opamp alone from 2.5nV/sq rt Hz to almost 3nV.  Of course that is still pretty low.  Also you don't want to tax the output current capability of the first stage too much.

And also as JR suggests, a little buildout R in series with the output is advised to ensure stability driving cables.

A full analysis of noise performance of preamps for moving iron cartridges is complicated, but there's a National app note with a very good discussion and example.  I don't have the ref at hand at the moment but it's been in a thread or two here.

All good advice... I offered the National topology as as one of several fairly simple ones in the public literature that are capable of delivering a real pole at 75usec and shouldn't suck using modern opamps. I am not endorsing that particular National opamp,,, or circuit, other than suggesting IMO it is better than what I've seen offered  elsewhere in this thread.

I recall an excellent noise treatment in the old national application notes for their LM381/LM387 series of opamps. http://www.national.com/an/AN/AN-104.pdf#page=1&search=%22Application%20Note%20104%22  It is a little amusing 35 years later to see what we considered low noise back in those days, but the laws of physics haven't been repealed, and typical  phono cartridges haven't changed much so this tutorial is still valid for any wishing to edumacate themselves in this narrow area.

I am trying hard to not just say do it like I did it, since that is boring to even me. Following a few general concepts enumerated in the thread, I believe an excellent sounding preamp can be thrown together with modern off the shelf opamps. Another general observation is use good capacitors in the RIAA EQ circuitry. Compared to 99% of the wanking about capacitor sound here and about, in such a playback EQ it really can matter. Polystyrene is my old favorite, but I suspect other good quality film dielectric could be used. 

Enjoy..

JR
 
Yes I think that is the app note, which contains essentially all of the material in the appendix of the old National Audio Handbook plus includes additional sources like i sub n of the preamp.

It also uses a different cartridge than the original article, and I think a better one at that---a Shure V15 rather than an ADC27.  I wish the Shure were still available.
 
Yes the old audio handbook I have from mid- '70s has a whole chapter on preamps (according to National.. but it is heavily LM381/LM387 intensive and not on their website as far as I could find..

If I was still messing with phono preamps I'd take a look at those  .3nV JFETS ( IF3602) from Interfet. A little pricey but anybody still messing with vinyl probably isn't doing it to save money.  They're just crazy quiet... Not that the preamp would be any quieter..  ::)

JR




 
simple as can be: http://www.geocities.com/rjm003.geo/rjmaudio/diy_pho5.html
discrete: http://www.tnt-audio.com/clinica/indiscreet.html
 
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