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Catman's Analog Musings

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Phono stages.  Is it horses for courses, or just the nature of records?

 

G'day all, years ago I had one of spoken voice/ music test records, and one thing that I'll always remember was the commentator saying, 'the tonal balance of records varies a great deal'.  Ain't it the truth?  I guess this is why no phono stage or even cartridge can sound perfect on 'all' records. 

 

Maybe this is a good case for using good tone controls.  That being said, I do have certain phono stages that sound superb on certain genres of music and others likewise!  Don't you just love the whole record thing?  Regards, Felix.      

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The attraction of 'good design'.

 

G'day all, whilst my general working knowledge of electronics is good, my ability to design stuff is limited to the very basic, simple block stages and the like.  The design of a complete phono stage is quite beyond me, requiring quite a high level of technical understanding, practical knowledge and measurement ability.  The are thankfully people out there who can.  For this reason Andrew Russell of hifisonix is one of these people.  His 'Simple, Accurate RIAA EQ Phono Amplifier' is a fine yet simple example of good design and it is rapidly becoming my favourite DIY phono stage design, and it impresses me at every listen!

 

I have learned a lot from reading his various design articles, and it is obvious that his excellent design work shows through in the performance!  I believe that he has another fully featured MM/ MC phono stage with excellent performance in the final stages of development, and that is well worth keeping an eye on!

 

Reflecting on what I had personally seen over the years it is apparent that there is 'good looking' gear available and for sale, but sadly as I have seen, 'good design' is not necessarily a part of the product and I can think of a few examples of this, and that is a real shame in my opinion.  Coming from a technical background, good design has always impressed me more than anything else!  Long may that trend continue!  Regards, Felix. 

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Posted (edited)

IC socket issues!

 

Maybe things like this happen in these crazy days, but today one of my DIY phono stages 'just stopped working' for no apparent reasons and all the usual faultfinding achieved 'nothing'.  Head scratching time!  Then I happened to bump one of the op amp sockets and things suddenly jumped into life! 

 

A few checks indicated an intermittent contact(s) on that 'high quality' op amp socket!  Mmmmmm.  I always prefer to use good quality IC sockets when possible for obvious (faultfinding) reasons but I know knowledgeable people who suggest that sockets should never be used in any case.  I wonder!  Regards, Felix.

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Posted (edited)

The bass response of modern 'chip' amps.

 

G'day all, I've had a new commercially made 'chip' based amplifier for a little while now which is excellent,  however one little thing is slightly curious.  With my old DIY (chip) amp I happily used an external active subwoofer with excellent results, however with this new amp the bass response, even with just the bookshelf speakers, seems much stronger than with my old setup and actually a subwoofer seems entirely unnecessary.  Is this good bass response 'typical' of modern 'chip' based amplifiers, or is something else at work here?  Regards, Felix.   

Edited by catman

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On 27/03/2020 at 8:03 PM, catman said:

Is this good bass response 'typical' of modern 'chip' based amplifiers, or is something else at work here?

unlikely "typical", but "possible" there's been some EQ applied...put it on a Cro with a dummy load - that will tell you if the output is flat

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On 21/03/2020 at 2:40 PM, catman said:

IC socket issues!

 

Maybe things like this happen in these crazy days, but today one of my DIY phono stages 'just stopped working' for no apparent reasons and all the usual faultfinding achieved 'nothing'.  Head scratching time!  Then I happened to bump one of the op amp sockets and things suddenly jumped into life! 

 

A few checks indicated an intermittent contact(s) on that 'high quality' op amp socket!  Mmmmmm.  I always prefer to use good quality IC sockets when possible for obvious (faultfinding) reasons but I know knowledgeable people who suggest that sockets should never be used in any case.  I wonder!  Regards, Felix.

Easy to have an intermittent contact on one leg of an IC/socket, when I installed a socket for the TDA1541 I scored a single crown version, but thought it faulty initially but it turned out to be a poor contact on one leg, re-seated and all was/is well.

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Posted (edited)

When do you most notice sonic differences during comparisons?

 

G'day all, I've been playing lots of records of late using mostly my DIY op amp phono stages and they all sound great so for a quick comparison tonight I plugged in my Rothwell Simplex and had a listen, and immediately on stylus set down the 'different' and unstressed/musical sound of the Simplex was readily apparent, however after a relatively short time it sounded much like any of my best phono stages.  That is  curious.  Acoustic differences and clues apparently are quickly absorbed and seemingly accepted as 'normal'.  Regards, Felix. 

Edited by catman
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Posted (edited)

What are the audible signs of a stylus that definitely needs replacement?

 

G'day all, this is a question that I've never really had a definitive answer to.  As I generally don't keep tabs on how much use my stylus has had (time wise), I am looking for a definitive answer to this.  With the Ortofon stylus 10 that I've just replaced whilst it looks fine with a simple x10 magnifier, and it sounds ok however I have noticed occasional bursts of severe playback distortion at times.  Replacing that stylus today, all occasional playback distortion is gone, so I guess that old stylus had reached its 'use by' date, yet that isn't a definitive sign of wear, or is it?  Any comments or thoughts?  Regards, Felix.        

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Reading another site today, which said that the first indication that a stylus needs replacing is inner groove distortion becomes apparent when it previously wasn't there. 

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Get yourself a little golf stroke counter and start to keep track of how many LPs on the stylus. 

While wear rates differ, as do longevity estimates, it will at least give you a general idea of the time used.

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office works or ebay

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On 03/04/2020 at 4:21 PM, catman said:

What are the audible signs of a stylus that definitely needs replacement?

 

G'day all, this is a question that I've never really had a definitive answer to.

 

True, Felix - and there are widely differing claims of diamond longevity floating around.  :lol:

 

My view is that by the time you start to hear wear-related distortion - the stylus is already worn enough to have done some groove damage.

 

So I use a clicker - as @GregWormald posted.  2800 sides = 1000 hours = replacement time.

 

Andy

 

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11 minutes ago, andyr said:

True, Felix - and there are widely differing claims of diamond longevity floating around.  :lol:

 

My view is that by the time you start to hear wear-related distortion - the stylus is already worn enough to have done some groove damage.

 

So I use a clicker - as @GregWormald posted.  2800 sides = 1000 hours = replacement time.

 

Andy

 

When I sent my Linn Troika with 1200 LPs played to be reconditioned, I was told after inspection that it could go for another 400 or so before damage was likely to be caused. I had it done anyway.

 

BTW--Cleaner records = less wear, so now I clean ultrasonically--(it's an audible improvement)--and am hopefully looking at more than 1500 LP plays.

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2 hours ago, GregWormald said:

When I sent my Linn Troika with 1200 LPs played to be reconditioned, I was told after inspection that it could go for another 400 or so before damage was likely to be caused. I had it done anyway.

 

BTW--Cleaner records = less wear, so now I clean ultrasonically--(it's an audible improvement)--and am hopefully looking at more than 1500 LP plays.

 

OK, so Linn was saying that - for the diamonds they use in the Troika - 1600 LPs should be good.

 

IE. 3200 sides instead of my estimate of 2800 sides.  :)

 

Agreed ... cleaner records = less wear.  Unfortunately, we just don't know whether the figures of 1000 hours or 1200 hours etc. for stylus life are for pristine grooves ... or not.  :(  As I don't want to degrade my grooves ... I'm going to assume the number refers to cleaned grooves.

 

Andy

 

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Posted (edited)

Humble pie time!

 

G'day all, I'd like to think that I'm not stupid and my general comments on phono matters are truthful and technically accurate, but alas I have to admit that a commercially made phono stage that I once regarded highly and actually recommended, has turned out to be a badly designed POS!  

 

It plays well but a little technical investigation has revealed some major design shortcomings one of which could actually cause amplifier damage because of a significant DC offset on the output!  Some amplifiers will happily tolerate this, but some amplifiers (like my own) will not!  In fact this is how I actually became aware of this design problem!  One of several I might add.  It is just as well that this particular unit is no longer in production.  Caveat Emptor!  Regards, Felix. 

Edited by catman
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Posted (edited)
19 hours ago, catman said:

Humble pie time!

 

G'day all, I'd like to think that I'm not stupid and my general comments on phono matters are truthful and technically accurate, but alas I have to admit that a commercially made phono stage that I once regarded highly and actually recommended, has turned out to be a badly designed POS!  

 

It plays well but a little technical investigation has revealed some major design shortcomings one of which could actually cause amplifier damage because of a significant DC offset on the output!  Some amplifiers will happily tolerate this, but some amplifiers (like my own) will not!  In fact this is how I actually became aware of this design problem!  One of several I might add.  It is just as well that this particular unit is no longer in production.  Caveat Emptor!  Regards, Felix. 

 

So this "commercially made phono stage " doesn't use output coupling caps, Felix?

 

If so - that is outrageous.  But, as you say ... "caveat emptor"!  :)

 

It's possible to design a circuit to null-out DC offset ... but this makes the overall circuit more complicated.  With my 'Muse', I chose the simple-circuit option but use output coupling caps that cost me A$250 the pair (and worse now, with the current state of the dollar!  :( ).  But this price is worth it IMO - as they sound good.  Very few commercial phono stages under $10K will use caps as pricey (and good-sounding)!  :o

 

Andy

 

Edited by andyr

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G'day all, yes that is one of the issues.  The overall design looks like it was derived from something much more complex with components removed to a bare minimum to keep it working!  Regards, Felix.   

 

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Phono stages for Jazz.

 

G'day all, on this otherwise morose sort of day I've just been playing John Abercrombie's excellent 'Timeless' album with my Rothwell Simplex phono stage and man it sounds great!  I've always loved the open and musical sound of the Simplex, and playing this album with my Rothwell Simplex (and Ortofon Super OM10), it sounds beautiful!  The Rothwell Simplex is a stunningly good phono stage!  Regards, Felix.   

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On 05/04/2020 at 5:42 PM, catman said:

Humble pie time!

 

G'day all, I'd like to think that I'm not stupid and my general comments on phono matters are truthful and technically accurate, but alas I have to admit that a commercially made phono stage that I once regarded highly and actually recommended, has turned out to be a badly designed POS!  

 

It plays well but a little technical investigation has revealed some major design shortcomings one of which could actually cause amplifier damage because of a significant DC offset on the output!  Some amplifiers will happily tolerate this, but some amplifiers (like my own) will not!  In fact this is how I actually became aware of this design problem!  One of several I might add.  It is just as well that this particular unit is no longer in production.  Caveat Emptor!  Regards, Felix. 

I have to make sure source components I use have either transformers or caps on the outputs to block DC as my amp has nothing on the inputs.

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Ok I'll admit it....transistors have a 'sound', op amps have a 'sound' and valves have a 'sound'!

 

G'day all, in the end although I can't readily explain it, my ears and careful listening tell me that all these three popular amplifying systems have a distinct 'sound'.  They can all sound excellent if well designed and constructed and although some delight in telling us that it is all in our 'imagination', my ears tells me that there is something quite distinctive in the sound of transistors, op amps and valves. 

 

As it presently stands the sound of my Rothwell Simplex is particularly 'musical' sounding along with my ANT Kora 3T SE which are both transistor or FET based units, without an op amp anywhere.  Don't get me wrong op amp circuitry can sound great as well, however there is a endearingly 'organic' sound to discrete circuitry that is to my personal liking!  Regards, Felix.    

 

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Posted (edited)

Resurrecting an old project!

 

G'day all, since commissioning a new amplifier and deciding that I didn't need my old active subwoofer anymore I have unfortunately seen the re-emergence of an old problem of lots of woofer cone movement with sub bass (below 20 Hz) audio when using my turntable (and playing records)! 

 

However I found a solution and it's all plugged in and working with one of my previously assembled ESP P99 'sub bass filter' modules.  At 36 db/octave roll off below 20 Hz, and it is 'very' effective.  I have a few others and maybe I'll use them too in other applications!  Regards, Felix. 

Edited by catman
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1 hour ago, catman said:

Resurrecting an old project!

 

G'day all, since commissioning a new amplifier and deciding that I didn't need my old active subwoofer anymore I have unfortunately seen the re-emergence of an old problem of lots of woofer cone movement with sub bass (below 20 Hz) audio when using my turntable (and playing records)! 

 

I do find this very strange, Felix - given when I listen to vinyl ... I don't see such (sub)woofer pumping!  (The subs' roll off point is 100Hz.)

 

So I'm wondering whether your arm/cart combo is producing a resonance in the wrong place?

 

1 hour ago, catman said:

At 36 db/octave roll off below 20 Hz, and it is 'very' effective.

 

Are you saying this filter's "@ point" is 20Hz?

 

Andy

 

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Posted (edited)

G'day mate....yes.  You obviously have your turntable set up perfectly but obviously I don't.  https://sound-au.com/project99.htm  Regards, Felix.  

Edited by catman
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The benefits of sub bass filtering with 'real world' record playback systems.  

 

G'day all, in my head it is interesting how one thing often leads to another as it were, and having just installed a sub bass filter into one of my record playing systems, I've been pleasantly surprised by the subjective improvement.  Clearly there is considerable merit in having good sub bass filtering where applicable, and that makes me wonder about what 'should' be amplified and what should be eliminated in early processing in phono playback systems! 

 

As is often the case, the devil is in the detail, and how it is done!  In many cases phono stages supposedly incorporate some kind of ‘rumble’ filter, which is frequently a simple capacitor filter invariably rolling off quite a bit of the wanted bass audio frequencies as well!  I once built a phono stage like this with very ‘light’ sounding bass.  It was terrible! 

 

A good sub bass filter is invariably a complex and precise piece of electronics.  The Elliott Sound Products P99 DIY sub bass filter is highly recommended, and is one of the best filters of this kind around in my opinion!  My DIY Akitika Phono Z also has excellent sub bass provisions which work well in practice.

 

Sub bass energy is often caused by record warp which are unfortunately very common, and phono cartridge/tonearm resonance issues which also tend to be common, at least that is my personal experience!  Eliminating this unwanted energy can greatly improve audio clarity through markedly reduced ‘intermodulation’ effects.  The commercially made KAB filter is also reported to be excellent.  Regards, Felix.       

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Felix, I've looked at this filter on Rod's site, and saw that it was a suggested compliment to his phono stage that I have read your favorable reports on. 

 

How useful would this sub-filter be for playing 78's?  Would something with a higher roll-off point be more useful for that context?

 

 

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