Resistors

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izzy wizzy
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#16 Re: Resistors

Post by izzy wizzy »

I have the sim already running so thought I'd sim that 2.5% variation. light blue to blue is 2.5% variation with what I chose as "right" in red. Phase are the bottom 3. That seems a very small difference to hear? Not doubting what you say and heard. Just trying to figure what's going on.

OK, I misread and altered what Mark has said about the series resistor by 2.5%. Will try the cap to see what happens.

eq25.jpg
Last edited by izzy wizzy on Sat May 02, 2020 6:23 pm, edited 3 times in total.
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#17 Re: Resistors

Post by izzy wizzy »

And this a 2.5% change in the big EQ cap. That's quite a big change.

eq25a.jpg
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Nick
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#18 Re: Resistors

Post by Nick »

Sorry, that’s my fault, it was the resistor that changed. From 205k to 200k. Measured difference is only about 0.5dB at 20Hz, but makes a big difference to the sound.Far more pacey and right. I was surprised what a large change in sound an small change in value and measurement made.
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#19 Re: Resistors

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Also, I use coupling cap sizes so I don't have that roll off below 50Hz. That in itself is causing more phase changes so probably masks the change I could hear. Running the sym the max phase shift is less that 3deg between 10Hz and 1k. And I agree the difference is phase is not that big, but whatever it is is certainly audible.
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#20 Re: Resistors

Post by IslandPink »

Whether you can hear that so clearly is definitely going to depend on your speakers, as they are typically all over the place ( on phase ) between 20 and 50Hz. I think I was experimenting at the time I had the Ariels, which are rolling off below 45Hz. Probably phase-leading, significantly, below 50.
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#21 Re: Resistors

Post by Greg »

Nick wrote: Sat May 02, 2020 7:38 pm Sorry, that’s my fault, it was the resistor that changed. From 205k to 200k. Measured difference is only about 0.5dB at 20Hz, but makes a big difference to the sound.Far more pacey and right. I was surprised what a large change in sound an small change in value and measurement made.
Indeed, on Nick’s prompt, I made this small change to my Long Dog Audio MCJ3 Hybrid Phono Amp and it removed the politeness of the sound, bringing in a more punchy, more acute and dynamic sound. At the time I drew an analogy of moving from a belt drive TT to an idler drive. That description still holds out for me.
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#22 Re: Resistors

Post by izzy wizzy »

I don't doubt anyone is hearing what they are. I trust ears. Really appreciate you guys putting it out there. I find it amazing there is an audible difference when the sim says little has changed. However, I hear changes that the sim confirms albiet even quite small ones. I think I read somewhere, and it could have been Morgan J, where these small changes are audible as they span many octaves and so change "character" of presentation. And then you read in mags that measure, how a phono stage within +/- 0.5dB is so good yet attribute all kinds of things to the sound it makes. I would love to see the sound related to it's deviations. To me it seems so obvious although of course there are other things going on. Do the better ones correspond to more accurate inverse RIAA? I'm aming for less than 0.1dB deviation this time in the sim, maybe even smaller. Again, just for fun to see what happens. I can't measure reality anyway.

Anyhoo, the closer I get to a best response, the better it sounds. Or, how varied my records sound. Same thing I suppose.

For the first time in ages, I'm going to get the caps absolutely right by parallel values. I never parallel caps (the small RIAA EQ value) so this is another preconceived idea to be challenged.

And Nick, when you say you use coupling caps that don't have that roll off, what are you using? BTW, note the scale on those graphs as if I need to tell you ;)
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#23 Re: Resistors

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Greg wrote: Sat May 02, 2020 9:21 pm
Nick wrote: Sat May 02, 2020 7:38 pm Sorry, that’s my fault, it was the resistor that changed. From 205k to 200k. Measured difference is only about 0.5dB at 20Hz, but makes a big difference to the sound.Far more pacey and right. I was surprised what a large change in sound an small change in value and measurement made.
Indeed, on Nick’s prompt, I made this small change to my Long Dog Audio MCJ3 Hybrid Phono Amp and it removed the politeness of the sound, bringing in a more punchy, more acute and dynamic sound. At the time I drew an analogy of moving from a belt drive TT to an idler drive. That description still holds out for me.
This is why I love phono stages. So much mileage in there for a bit of fiddling around :)
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#24 Re: Resistors

Post by Nick »

470nf into 200k first resistor,

I agree entirely with your point about the variation of RIAA and the potential to affect sound, I have seen several commercial phono stages and most had clearly incorrect RIAA when measured. So far out that its not an accident. I suspect that they are designed that way to give a "character" that they hope will create a following. Also I am now suspicious of a lot of the changes I have heard in phono stages with various component changes that may in actuality be slightly changing the riaa eq. I don't think I could have seen this level of difference before but the R&S UPL lets me insert a numerically calculated RIAA filter to equalise the signal out so I can get a lot closer to an accurate measurement than in the past not only seeing variations of less that 0.1dB clearly but having a known "correct"

To give you a bit of background to the change I made. The hybrid phono has sold fine, many happy owners, good reviews. But the only nagging compared to earlier version was the sound was a little polite. I assumed the difference was the jfet. Older version s used a jfet that claimed to be a Toshiba from ebay, but I think is actuality a different one re-badged. I started using the LSK170 as it was current production. I decided to get o the bottom of what caused the difference, so tried all sorts of obvious things to no effect. I then took another look at the RIAA and decided to tweak it as flat as I could. I was within 0.2dB other than below 70Hz when the response started to rise a little to 0.5dB at 20Hz. So I tweaked that down. And to my surprise the sound was fixed. I suspect now what I thought was the jfet sounding different was in fact the different gm causing a different Rout on the first stage so having a similar effect as altering the first resistor.

The difference is not a subtle one, but its not a change in tone, its a change in the ability of the thing to play rhythmically that’s been altered. I told Greg about what needed changing, but I didn't tell him what I heard. What he reported matched what I heard.
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#25 Re: Resistors

Post by izzy wizzy »

Fascinating post Nick. Found this quite exciting so may rant or repeat myself. What you found is similar to what I've found over the years but without the ability to measure anything. This thread started as a way to making the EQ more accurate. The sound of the resistors themselves was a side issue I wanted to explore coz why not. So good to hear that you are able to corelate these small changes not only with your ears but some measurements as well. I get tired of hearing how we can't discern these small changes as our hearing isn't good enough reflected in some ABx test scenario but lets not go there :)

Every time I've tried to get the thing more accurate, the better it plays music, which sounds silly, but I mean it holds together musically, rhythmically over a wider band. It's the one thing I aim for rather than "a sound" which I think you were alluding to in some commercial offerings. Had always wondered why in the early days, many commercial offerings I had circuits of were not very accurate (in my view).

I came to phonos by building ARC versions or clones, SP3,6,8,10,11. They use the term "high definition" and they use techniques and shaping to make things sound that way. I found it tiring in the end and went on my own journey but it still took me ages to shake off that sound from my designs. Part of this resistor type selection was for the first time to refine the "sound" to my taste. That Nick and Greg have reported good things on this is really encouraging.

Will also try increasing the coupling cap to see what happens. Have a range of values in film/foil caps of the same type to do this. Assume you are cap coupling into the whole EQ whereas I cap couple after the EQ into the 2nd stage. Will try going back to direct coupling having rejigged the first stage OP point but that's a different story.
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#26 Re: Resistors

Post by Nick »

Yes, I couple into the riaa to allow me to not worry over the eq cap voltage ratings. FWIW, I use Mundorf ZN Film into the riaa.
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#27 Re: Resistors

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izzy wizzy wrote: Sat May 02, 2020 9:29 pm
This is why I love phono stages. So much mileage in there for a bit of fiddling around :)
Must say I've found this thread very interesting. Almost making me think i need to build a Phono just to fiddle with..
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#28 Re: Resistors

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Come on in - the water's lovely !

re. resistors - I should say that most of the improvements I heard from resistor swaps are in the treble and high treble. Removal of 'crud' or edginess, extra tone higher up.
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#29 Re: Resistors

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IslandPink wrote: Sun May 03, 2020 4:46 pm Come on in - the water's lovely !

re. resistors - I should say that most of the improvements I heard from resistor swaps are in the treble and high treble. Removal of 'crud' or edginess, extra tone higher up.
More like join the loonies .... sorry, yeah come on in :)

Might get some crud removal if there's some to be had, excellent, and some more of that stuff you talk about would be a bonus. Spose it's like a lot of things; don't know it's there until it's gone. The Kiwames are reasonably priced so here's hoping. I'm excited :bounce:
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#30 Re: Resistors

Post by Nick »

Yep, you should Steve. I think there is more of a challenge getting a phono right than just about anything. Though preambles are harder than many think IMHO.

I agree with you Mark about resistors and HF crud, but I am personally unsure if the resistor is the cause, or if "softer" types are just masking what is there already, or preventing it causing problems later in the chain. Somewhere between warm and edgy is clarity.
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