Phono Preamp needed, or just new Turntable? - AVS Forum
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post #1 of 33 Old 01-08-2012, 02:14 PM - Thread Starter
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I recently purchased an Onkyo NR809 AVR and two Infinity P362s as a "beginners" setup (60% music 40% movies/tv).

I'm extremely pleased with the overall sound so far - I've watched a few blu-rays and listened to some CD's (both on PS3).

I have an old Technics SL-B20 turntable that I rescued from my parent's crawl space. The NR809 has a Phono input, so I plugged it in and let her rip.

The sound is flat and quiet, but it's there. Question is, do I need a Phono preamp to increase the power even though the AVR has a dedicated Phono input, or is the poor audio due to the poor quality of the turntable? I'd eventually like to purchase a new turntable, but would like to know if I can devote the entire budget to the turntable and forgo a preamp (I'd be willing to spend around $500).

Any help would be greatly appreciated!
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post #2 of 33 Old 01-08-2012, 02:38 PM
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Lyle;

The phono preamp has two functions; gain and equalization.

The thing you may or may not know is that a vinyl record has the bass severely reduced in amplitude during the production of the master. If they didn't do this the cutting lathe would swing so far during the long bass cycles that the record would hold about 3 minutes on each side...lol.

So anyway, the phono preamp has to have a filter which "equalizes" the information coming off of the record by having much higher gain (100 times more) at low f than high f. The quality of the equalization circuit is a major deal for the sound quality.

Look up "RIAA equalization" for more detailed information.

Receivers and even mid-priced amps usually do a cheap circuit for this and it isn't very good. You are probably going to want to get a decent dedicated phono preamp no matter what. The Musical Fidelity for $99 is very very good; better than some costing hundreds more.

Now about that turntable; 99% chance it has bad bearings and dried-up grease (or will soon) after sitting for years. Add that to how good it was to start with???? and maybe you don't want to go there...lol. Most old turntables are like old dogs; they can't hunt no more.

One very good solution might be the Thorens TD-170-EV turntable at Audio Advisor. It has been marked down from $649 to $299, and has a phono preamp built into the turntable. I do not know how good the phono preamp is, but Thorens has has a great reputation for making very high quality turntables and tape decks for over 50 years, so it may not be too bad. In any case, the phono preamp is basically a freebie with a very good deal on a good turntable. I don't see how you can go wrong there.

The Thorens preamp is almost certainly better than what is in almost any receiver. I would just buy it and hook it up to your receivers "AUX" input and I'll bet you smile a lot.

There is also the Thorens TD-158 for $199. The old turntable could be a money pit and might not be kind to your records.



Quote:
Originally Posted by Lylelem View Post

I recently purchased an Onkyo NR809 AVR and two Infinity P362s as a "beginners" setup (60% music 40% movies/tv).

I'm extremely pleased with the overall sound so far - I've watched a few blu-rays and listened to some CD's (both on PS3).

I have an old Technics SL-B20 turntable that I rescued from my parent's crawl space. The NR809 has a Phono input, so I plugged it in and let her rip.

The sound is flat and quiet, but it's there. Question is, do I need a Phono preamp to increase the power even though the AVR has a dedicated Phono input, or is the poor audio due to the poor quality of the turntable? I'd eventually like to purchase a new turntable, but would like to know if I can devote the entire budget to the turntable and forgo a preamp (I'd be willing to spend around $500).

Any help would be greatly appreciated!

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post #3 of 33 Old 01-08-2012, 02:56 PM - Thread Starter
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Thanks for the reply, commsysman.

Looks like the Thorens TD-170-EV is a great deal.

And, since you obviously know what you're talking about - any suggestions for a solid CD Player? I've been looking at upgrading to the Oppo 93 for Blu-Ray, and I've read that playing CDs on the player yields quality results.

My apologies for the ignorant questions...I've just begun my audio quest!
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post #4 of 33 Old 01-08-2012, 03:09 PM
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Quote:
Originally Posted by commsysman View Post

The quality of the equalization circuit is a major deal for the sound quality. [...] Receivers and even mid-priced amps usually do a cheap circuit for this and it isn't very good.

I beg to differ!

It doesn't much matter what other circuitry there is, the RIAA curve is usually defined by two capacitors and two resistors. Pretty hard to make a "cheap" version ... or an "expensive" version for that matter!

Whatever the issue with quality of sound there may be, it will have squat to do with the "RIAA" circuit, per se!!

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post #5 of 33 Old 01-08-2012, 03:16 PM
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What you obviously need to know about RIAA equalization circuits I could write a small book about. As a matter of fact, the Audio Engineering Society has published many papers over the years by highly qualified engineers on various ways to eliminate phase distortion and other problems in these RIAA EQ circuits. They would make a good place for you to read, if you have an engineering degree and adequate time to read up on it.

What you describe is the cheapest possible circuit, guaranteed to produce phase distortion and sound terrible! Actually such a circuit cannot even be properly described as an RIAA EQ circuit at all, since the RIAA standard defines 3 rolloff points at 50 HZ, 500 HZ, and 2122 HZ. I wonder how one would build 3 filters with 4 components? No filter circuit I studied in my engineering classes ever resembled that, and I think we covered the ground pretty well.

Look up the circuit of an Audio Research PH-5, for example, if you want to see a sophisticated implementation of one iteration of a good RIAA EQ circuit. You can see a photo of the interior of the PH-5 phono preamp at

www.arcdb.ws

The RIAA EQ circuit looks like over 60 components to me, not counting the power supply circuits or the front panel display circuits ( of course that is two channels...).

Everything you are saying makes absolutely no sense to a competent experienced circuit designer (which I happen to be), and does not agree at all with any of the experts on the subject.

One good modern design paper, with schematics and detailed design information, is available at

www.angelfire.com under the title "A RIAA Equalized Preamplifier" by Danyuk and Pilko (1990).

Your quote of Daniel Boorstin is quite to the point in this case; it's good of you to mention it.




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Originally Posted by cavu View Post

I beg to differ!

It doesn't much matter what other circuitry there is, the RIAA curve is usually defined by two capacitors and two resistors. Pretty hard to make a "cheap" version ... or an "expensive" version for that matter!

Whatever the issue with quality of sound there may be, it will have squat to do with the "RIAA" circuit, per se!!

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post #6 of 33 Old 01-08-2012, 03:38 PM
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Quote:
The sound is flat and quiet, but it's there. Question is, do I need a Phono preamp to increase the power even though the AVR has a dedicated Phono input, or is the poor audio due to the poor quality of the turntable?

"Flat and quiet" could mean a lot of things, so take any long-distance diagnosis (including mine) with a grain of salt. First thing you should know is that it's common to have to crank the volume somewhat when listening to a turntable, compared to other inputs. If that's the only problem, then you have no problem.

If it's an old table that's been in mothballs for awhile, you might try replacing the cartridge. Don't forget you need a p-mount cartridge. A new belt wouldn't hurt, either.

I doubt the problem is with the phono input of the AVR, unless it's defective out of the box (always a possibility). Best thing to do is try the turntable in another system. But I'd try a new cartridge before I tried a new phono preamp.

If you can't explain how it works, you can't say it doesn't.—The High-End Creed

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post #7 of 33 Old 01-08-2012, 03:39 PM
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Lyle;

I am using an Ayre C5xe/mp, but that is going for $6000 last time I checked. It's as good as they get. Another one that is just about as good, which I have in my other system, is the Sony SCD-XA5400ES, which was only $1500 when it was available, but as far as I know Sony has quit making it for the time being. It really was dirt cheap for its sound quality; it beats out players that cost $5000, in most cases. It's a tragedy that they have quit making it, but the dealers that should have carried it never did, because Sony isn't usually carried by the same dealers that carry such a high level of equipment.

There are some good ones for around $1000, but actually the Oppo DVD players are very good at playing audio CDs; probably as good as any dedicated CD player for less than $500.

The Marantz 8004 SACD/CD player is pretty good, but you are probably almost as well off playing the CDs with your Oppo DVD or Blu-Ray player.

For $499, the Oppo BDP-93 is one heck of a machine, and plays both SACD and CD very well, so you would have to spend at least $1000 to get better.

I wouldn't describe your questions as ignorant at all; the truly ignorant thing is to not try to find answers you need.



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Originally Posted by Lylelem View Post

Thanks for the reply, commsysman.

Looks like the Thorens TD-170-EV is a great deal.

And, since you obviously know what you're talking about - any suggestions for a solid CD Player? I've been looking at upgrading to the Oppo 93 for Blu-Ray, and I've read that playing CDs on the player yields quality results.

My apologies for the ignorant questions...I've just begun my audio quest!

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post #8 of 33 Old 01-08-2012, 03:56 PM
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And, since you obviously know what you're talking about - any suggestions for a solid CD Player? I've been looking at upgrading to the Oppo 93 for Blu-Ray, and I've read that playing CDs on the player yields quality results.

Given that you've got an AVR, anything that plays disks will give you excellent (and equivalent ) sound quality. Choose one for its video quality/features (unless you're specifically interested in hi-res audio disks).

If you can't explain how it works, you can't say it doesn't.—The High-End Creed

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post #9 of 33 Old 01-08-2012, 04:00 PM
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I agree that you would have to set the volume higher with the turntable than a cd player. Also if the cartridge is old and the magnets have lost strength the output would be less. You might want to also check the manual and make sure the phono inputs do not have a bypass switch so it could be used for a different component.

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post #10 of 33 Old 01-08-2012, 04:59 PM
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CD player output voltages vary, and the output of MM phono cartridges vary a tremendous amount, and the gain of phono stages vary considerably.

Given all those variables, it is very hard to predict which will need more amplifier gain to reach the same level.



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Originally Posted by JohnMichael View Post

I agree that you would have to set the volume higher with the turntable than a cd player. Also if the cartridge is old and the magnets have lost strength the output would be less. You might want to also check the manual and make sure the phono inputs do not have a bypass switch so it could be used for a different component.

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post #11 of 33 Old 01-08-2012, 05:42 PM
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On page 19 of the receiver owner's manual, it talks about connecting an input to the phono input WITH THE PHONO PREAMP TURNED OFF". OBVIOUSLY, THERE IS A WAY TO TURN IT ON OR OFF. YOU MAY HAVE IT TURNED OFF. Since they do not mention a physical switch, my guess is that it a menu-selectable control function somewhere in the Audio Setup menu.

I suspect you are misreading this. What they probably mean is that you should connect the turntable to the phono input with any preamp in the turntable turned off. His turntable doesn't have a selectable phono preamp, so it should work just fine.

EDIT: Just checked the manual myself, and that note does indeed refer to a turntable with a built-in preamp. That's the preamp they want off.

If you can't explain how it works, you can't say it doesn't.—The High-End Creed

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post #12 of 33 Old 01-08-2012, 05:55 PM
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You are absolutely right; after going through the whole damn setup hoo-ha in the manual, I went back and it suddenly became clear...grrrr...lol. It can't be turned off.

So if he gets a turntable with a built-in preamp, it needs to be connected to the TV/CD input on the receiver, like they say in the manual (also the same if he wants to use an external phono preamp).

That is no problem since he is going to be using the DVD player for the CDs anyway.


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Originally Posted by mcnarus View Post

I suspect you are misreading this. What they probably mean is that you should connect the turntable to the phono input with any preamp in the turntable turned off. His turntable doesn't have a selectable phono preamp, so it should work just fine.

EDIT: Just checked the manual myself, and that note does indeed refer to a turntable with a built-in preamp. That's the preamp they want off.

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post #13 of 33 Old 01-08-2012, 06:07 PM
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You are absolutely right; after going through the whole damn setup hoo-ha in the manual, I went back and it suddenly became clear...grrrr...lol.

Yeah, these things are so bloody complicated these days, plus there are so many different kinds of things you're plugging into them. It's no wonder the manuals are 100 pages long.

Not like in my day. If you could figure out to plug the phono into the phono input, you were good to go!

If you can't explain how it works, you can't say it doesn't.—The High-End Creed

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post #14 of 33 Old 01-08-2012, 10:32 PM - Thread Starter
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Quote:
Originally Posted by commsysman View Post

You are absolutely right; after going through the whole damn setup hoo-ha in the manual, I went back and it suddenly became clear...grrrr...lol. It can't be turned off.

So if he gets a turntable with a built-in preamp, it needs to be connected to the TV/CD input on the receiver, like they say in the manual (also the same if he wants to use an external phono preamp).

That is no problem since he is going to be using the DVD player for the CDs anyway.

Thanks again for all the help to everyone.

Follow up question - would I be better off going with a solid turntable with a built-in phono preamp (like the Thorens TD-170-EV) and connecting it to the TV/CD input on my Onkyo? Especially if the Phono circuits in the AVR aren't of high quality?
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post #15 of 33 Old 01-09-2012, 01:59 AM
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Well, that turntable was $650 recently, so it seems like a heck of a deal at $299. Seems like a good way to go.



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Originally Posted by Lylelem View Post

Thanks again for all the help to everyone.

Follow up question - would I be better off going with a solid turntable with a built-in phono preamp (like the Thorens TD-170-EV) and connecting it to the TV/CD input on my Onkyo? Especially if the Phono circuits in the AVR aren't of high quality?

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post #16 of 33 Old 01-09-2012, 07:16 AM
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Quote:


Follow up question - would I be better off going with a solid turntable with a built-in phono preamp (like the Thorens TD-170-EV) and connecting it to the TV/CD input on my Onkyo? Especially if the Phono circuits in the AVR aren't of high quality?

No, at least not for the reason you've suggested. The phono preamp included in turntables isn't likely to be any better than the one in your AVR. To repeat, the phono stage is not your problem.

If you can't explain how it works, you can't say it doesn't.—The High-End Creed

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post #17 of 33 Old 01-09-2012, 08:33 AM
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my 1611:
turn the master volume up and i only get 12db out of the speakers
have a new turntable
checked out the speakers and all is well
turn on the tuner and have more volume than i need (which is good)

so, since i have the turntable input on the DVD should i change it to Aux or TV?

rsvp
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post #18 of 33 Old 01-09-2012, 01:56 PM
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+1 to checking the turntable/cartridge before signaling out the pre-amp. Do you know anyone else with a turntable that you could hook up to in order to start some process of elimination?

FWIW, my two sources are a stereo DAC and a Pro-Ject Debut III plugged into my receiver's phono input, and the TT is a good 7-10db quieter than my DAC

2.0 > 7.1
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post #19 of 33 Old 01-09-2012, 01:57 PM
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Quote:
Originally Posted by mcnarus View Post

the phono preamp included in turntables isn't likely to be any better than the one in your AVR

+1 as well

I would stay away from built-in phono amps on turntables in general

2.0 > 7.1
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post #20 of 33 Old 01-09-2012, 04:55 PM
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tuquer;

You MUST HAVE a phono preamp to both increase the signal voltage and to perform RIAA Equalization on the phono signal before it goes into the AUX input (or any of those other inputs).

The bass on the vinyl record is recorded at a VERY low level compared to the higher frequencies, so this process must be reversed by a special RIAA equalization filter and amplifier before it can go into a normal input on any amplifier or receiver.

Read the section on "RIAA EQUALIZATION" at WIKIPEDIA; that will help you understand.

I recommend that you go to Audio Advisor online and get the Musical Fidelity V-LPS PHONO PREAMP for $99, and then connect your turntable to its input jacks...and then its output will connect to the AUX input jacks on your receiver.



Quote:
Originally Posted by tuquer View Post

my 1611:
turn the master volume up and i only get 12db out of the speakers
have a new turntable
checked out the speakers and all is well
turn on the tuner and have more volume than i need (which is good)

so, since i have the turntable input on the DVD should i change it to Aux or TV?

rsvp

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post #21 of 33 Old 01-09-2012, 05:01 PM
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tuquer:

Before you go buying commsysman's favorite preamp, please tell us:

1) what turntable you are using
2) what receiver you are using
3) how you have the turntable connected to the receiver
4) what problem you are experiencing

I don't think your post was clear enough for anyone to give you sound advice.

If you can't explain how it works, you can't say it doesn't.—The High-End Creed

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post #22 of 33 Old 01-09-2012, 05:12 PM
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LOL;

Turntable connected to the DVD input???

You don't think his problem (and the solution) is obvious?

He does not have a phono preamp connected.

I was trying to keep his solution as simple as possible; he already answered 3 and 4, and what difference does 2 make?


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Originally Posted by mcnarus View Post

tuquer:

Before you go buying commsysman's favorite preamp, please tell us:

1) what turntable you are using
2) what receiver you are using
3) how you have the turntable connected to the receiver
4) what problem you are experiencing

I don't think your post was clear enough for anyone to give you sound advice.

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post #23 of 33 Old 01-09-2012, 05:23 PM
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I was trying to keep his solution as simple as possible; he already answered 3 and 4, and what difference does 2 make?

I think, before you go pushing a new preamp on him (do you get a commission on this one or something???), you should at least establish that he doesn't have a phono stage somewhere in his system already. Given the sketchiness of what he posted, i'm not making any assumptions.

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post #24 of 33 Old 01-10-2012, 03:50 PM
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Quote:
Originally Posted by mcnarus View Post

tuquer:

Before you go buying commsysman's favorite preamp, please tell us:

1) what turntable you are using
2) what receiver you are using
3) how you have the turntable connected to the receiver
4) what problem you are experiencing

I don't think your post was clear enough for anyone to give you sound advice.

turntable is a new Music Hall with a Technica Ctg. - - it was playing on the showroom floor on the Receiver i purchased. It has a built in preamp
the receiver is a Denon 1611
i pluged it into the DVD port
PROBLEM: Only can get 12db of performance out of the system (the scale on the front of the 1611) but when i switch to radio it is plenty loud enough.

hope this helps
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post #25 of 33 Old 01-10-2012, 06:48 PM
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Sounds like you don't have the preamp switched in on the turntable.

If you can't explain how it works, you can't say it doesn't.—The High-End Creed

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post #26 of 33 Old 01-11-2012, 07:15 AM
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Quote:
Originally Posted by commsysman View Post

I wonder how one would build 3 filters with 4 components? No filter circuit I studied in my engineering classes ever resembled that, and I think we covered the ground pretty well.

Here it is - the simplest, purest form - with a four-component RIAA network in the feedback loop of a TL071 (or similar) opamp. If you were to replace this four-component network with a single resistor you would have a text-book vanilla linear amplifier.

Don't know what you studied in your engineering class but this network provides the required 75µS, 318µS and 3180µS time constants and is an accurate reciprocal of the network used to encode the vinyl disk in the first place.

Not sure how a "competent experienced circuit designer (which [you] happen to be)" would do it differently, but that's how I (and many other design engineers in the industry) have successfully designed and manufactured RIAA preamps for broadcast use over the last 45 years.

This isn't any different than Jung, Lipschitz, etc., have discussed over the years. Its not rocket science.

You originally stated that "The quality of the equalization circuit is a major deal for the sound quality". I rebutted that "the RIAA curve is usually defined by two capacitors and two resistors. Pretty hard to make a "cheap" version ... or an "expensive" version for that matter".

Perhaps you would enlighten me and provide an example of an "expensive" version of this network that would provide ANY improvement in defining the RIAA curve.
LL

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post #27 of 33 Old 01-11-2012, 11:11 AM
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Quote:
Originally Posted by cavu View Post

Here it is - the simplest, purest form - with a four-component RIAA network in the feedback loop of a TL071 (or similar) opamp.

Hi Cavu,

Did you forget the link?
Thanks in advance.
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post #28 of 33 Old 01-11-2012, 11:28 AM
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Originally Posted by MarkHotchkiss View Post

Hi Cavu,

Did you forget the link?
Thanks in advance.

From the LM4562 datasheet, but it's a pretty generic circuit.
The 4 components cavu is talking about are the 15n, 4n7, 200k and 16k. Replace them with a 21k5 resistor and you'll have a flat amp with the same 1khz gain.
LL
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post #29 of 33 Old 01-11-2012, 11:31 AM
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Originally Posted by MarkHotchkiss View Post

Did you forget the link?

It *WAS* there this morning!@#$%

Uploaded image again and reset.

Thanks for letting me know.

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post #30 of 33 Old 01-11-2012, 11:51 AM
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Originally Posted by A9X-308 View Post

it's a pretty generic circuit. The 4 components cavu is talking about are the 15n, 4n7, 200k and 16k.

C'est ça!

It is indeed simple. That's my point. And its the inverse of the same simple circuit used in the mastering lathes. How could it be done more effectively?

IAC, sounds like you and I have similar backgrounds; I started as chief engineer at a 50kW AM and 360Kw FM (most powerful in the world) in the late sixties and went into pro audio product design later.

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