Seems I followed up my own post on the overload phenomenon, yet somehow it fails to appear here. Probably my fault for not clicking the green button. Anyway, I did some further reading on the phono overload phenomenon. Seems it is a complex subject, because cartridge voltage output rises with frequency. The standard spec is for a velocity of 5cm/sec at 1kHz, as most know. The input of the Pulsus is said by HFN to be overloaded at a threshold of 46mV with a 4.52mV reference (meaning for a cartridge output of 4.52mV). Elsewhere I read that the acceptable spec is that the overload margin of a good phono stage ought to be 20db above the reference input voltage. In this case, HFN measured 19.6db for the Pulsus, with reference to 4.52mV input, another way of saying the 46mV upper limit. With the Ortofon 2M output at 5mV, that would slightly reduce the overload margin, but by a probably insignificant amount.
dynacolum, you wrote, "The Avid, at 48dB gain is apparently too sensitive to overloading by your not abnormally high output MM cartridges". But the phono gain is not by itself a measure of the overload margin. That depends heavily on the topology of the input stage. Also, tube MM phonos tend to have a higher overload margin than solid state MM phonos. And 5mV is not an abnormally high output for MM cartridges. In fact, that value is often taken as standard for an MM cartridge.
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I can vouch for the cable from turntable to phono stage make a big difference.
Interesting. But neither of my TTs has removable cables...aren't we talking surgery to replace those?
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It’s not obvious to me that the phono stage per se is responsible for the “problem”, if it even is a problem.
It's not obvious to me either, other than by process of elimination it is the combo of those carts with that phono pre that yields distortion. I have a few integrated amps with phono stages in them...I will see if I can reproduce the distortion through anything else.
The above article also says that the headroom isn't as indicated in the specs. And those carts have been measured at hotter than 5mV albeit as above there is some question about that.
What I do know is that specific combination produces distortion. The Avid is really good at digging out details from some records, and with the shibata on the 2M Black and Black SE I get some great detail, again from some recordings. Those that are at higher volume are the issue.
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@jji666 I can vouch for the cable from turntable to phono stage make a big difference. My Music Hall mm5-3 came with its own, directional, RCA cables. They’re the best I own, and, I think, play a major role in the sound quality of the vinyl on my system. My phono stage is rather modest, but I’m not getting any distortion of which I’m aware. Good luck sorting your situation.
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This review at HFN says the Avid has an overload margin at MM inputs of 46mV.
https://avidhifi.com/storage/uploads/cms/pdf/85/6345755481a21/2012%20HIFI%20NEWS%20PULSUS.pdf
It’s not obvious to me that the phono stage per se is responsible for the “problem”, if it even is a problem.46mV is 10X the cartridge output at a stylus velocity of 5cm/sec at 1kHz. Decent headroom at least. Further, HFN auditioned it with a Shure V15, which I believe also has nominally a 5mV output. Viridian made a good point about capacitance. Check phono cable capacitance. Then check the recommended capacitance for the cartridge and the input capacitance of the stage. Input capacitance adds to cable capacitance.
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Sell both your phono preamps. The Avid, at 48dB gain is apparently too sensitive to overloading by your not abnormally high output MM cartridges, and the Pro-Ject because you don’t respect its quality. Then buy a Spartan 20, which is £500 and has impeccable accuracy, generous overload margins, and negligible noise. You will be hearing your records, not your preamp.
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Excessive capacitance with a MM cartridge will cause a peak in the audible range before any roll off at the top of the range, and this will be perceived as added brightness.
https://www.hagtech.com/loading.html
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Not too bright, actually. There's no sibilance, for example.
Too hot - as in loud transients and other loud passages seem to be creating distortion, and doesn't seem to occur with my other phono pre.
In general, I enjoy the sound. But every third or fourth LP, maybe the louder ones, seem to have some distortion.
As above I am also adjusting my line stage to see if a higher input setting helps reduce it. Ran out of time yesterday...
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It’s interesting to read that the original poster found Ortofon’s too bright. Through my NAD phono preamp I find Ortofon’s flat and rolled off at the top. Much better synergy with AT’s and Goldring’s. I guess everyone experiences sound differently.
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"Bill, Not a good idea because of capacitance. Capacitance will cause a HF roll off probably before you notice a loss of gain."
I agree, my idea was to test to see if a loss of gain helped by using a set of long cables if they are available. Then having a pair of phono cables made with an increase in resistance, but by being normal length not an increase in capacitance. Steven Huang who owns Audio Sensibility in Toronto is an electrical engineer and my go-to guy for all things wire. I believe he may be able to help.
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"The Pro-ject phonostage sounds OK...but it isn’t at the same level that the Pulsus is "supposed" to be...at least judging by price and reviews."
That is no guarantee that it will sound good in your system!
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"I just set inputs on the preamp to 2.8v - up from 2.0." What does that mean? And are you referring to the phono stage or to your linestage?
Referring to my line stage, just in case the distortion was happening there. It may actually be both, in the sense that the hotness of the cart combines with the high gain of the phone preamp to create a cascade of distortion issues.
I don't think it is an alignment issue, in the sense that it happens with two different TTs and I recall having had this issue for a long time - I just hadn't focused on vinyl for a number of years and am now re-living what I had thought was the issue years ago.
The challenge is that I really do not want to waste my investment in all of these 2M carts or in the Pulsus phono stage. But they don't seem to like each other too much. The Pro-ject phonostage sounds OK...but it isn't at the same level that the Pulsus is "supposed" to be...at least judging by price and reviews.
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Bill, Not a good idea because of capacitance. Capacitance will cause a HF roll off probably before you notice a loss of gain. That’s throwing the baby out with the bathwater.
"I just set inputs on the preamp to 2.8v - up from 2.0." What does that mean? And are you referring to the phono stage or to your linestage?
If the cartridge actually puts out 8.6mV RMS at 5 cm/sec, that is quite a bit off of the factory spec of 5mV, presumably representing peak to peak voltage. "RMS" voltage I think if memory serves is calculated by dividing the peak to peak voltage by 1.414 or square root of 2. That means peak to peak V was higher than 8.6V. I don’t get it; I doubt Ortofon specs would be that far off from reality. Then I found this on the Steve Hoffman forum:
"Recently, I have attempted to make sense of some conflicting measurements of the output voltage of various phono cartridges from different sources. The infamous one here are the measurements of the 2M Black in particular, comparing the results of HiFi World (HFW) with those of Miller Audio Research (MAR). I ended up emailing HFW and got a response from them that may explain the discrepancy.
To recap, HFW said the output of the 2M Black measured at 8.6mV (5cms/sec). From my email exchange, it appears they actually measured at 3.54cms/sec and "converted up" to 5cm/sec. MAR’s test said 5.79/5.73mV (L/R 5cms/sec). HFW thinks the difference is due to different test records (yes, I’ve experienced that) but also the differences between peak vs. RMS standards for measuring the output. Of course that wasn’t mentioned as far as I can see in either test result.Using a quick conversion calculator, it looks like 8.6mV peak voltage is equivalent to 6mV RMS. That’s pretty close to the MAR results, so this appears to make sense."
The next post says that HiFi World (HFW) probably erred in labeling their result "RMS". So their number should be divided by 1.414. In other words, the HFW value of 8.6mV is probably not an RMS voltage and is in other ways erroneous. Stick with the idea the 2M Black makes 5mV, like Ortofon says it does. Even the above explanation of why the HFW value is wrong is fuzzy.
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Thanks! Well I suppose a passive line stage would be similar. I do worry about loss of quality with such measures.
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I know this is kind of a crazy idea, but desperate times call for desperate measures and all that. What you need seems to me is a bit of line loss between the cartridge(s) and the phono stage. Do you have an extra long set of phono cables you could try? I have a set that I use for my subs, for example, that reach across the room. If you have something like that you might give it a try just to see if it helps. The guy I get all my wires from could make a set of special phono cables that would provide the mathematically correct amount of resistance to get the job done. If you have a guy like that you might give him a call. If you want my guy's contact info send me a private message.
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Actually, the math above was helpful. I just set inputs on the preamp to 2.8v - up from 2.0. If the Bronze and the Black are really closer to 8mV then 2.0 was too low.
Checking now to see if there is any improvement.
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Thanks all. Check out these measurements:
https://www.hi-fiworld.co.uk/index.php/vinyl-lp/25-cartridges/174-ortofon-2m-bronze-2m-black.html?start=3
They measure the output of the Bronze at 7.9 and the Black at 8.6. Those are pretty hot, yes? It may vary by individual cart.
Also, I have the bronze and the black mounted on different TTs and they both display this issue with the Pulsus. The Pulsus is otherwise a super nice phono pre, which is why I would like to keep using it.
So there is no reasonable way to tame the output of the cartridges?
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The Ortofon Black produces 5mV at a stylus velocity of 5 cm/sec. The Avid Pulsus phono stage provides 48db gain on its MM inputs. 48db gain is roughly a 250X voltage gain. So the output of the Pulsus would be about 1.25V. That per se is not going to overload your linestage high level inputs which ought to be capable of tolerating it. The question is what is the overload margin of the Avid Pulsus inputs on MM. Which is to ask how much signal voltage above 5mV is needed to overload the circuit. Usually phono stages can have a better overload margin on their MM inputs compared to the MC inputs of the same unit, but I cannot find the overload specs for the Pulsus. You might ask your dealer or Avid whether the 2M Black, a very popular cartridge, might overload the MM inputs. But my guess would be no. And of course all that other stuff mentioned by Viridian is worth thinking about. I don't recommend increasing VTF by as much as 0.5g on a permanent basis, if that increase leads to VTF higher than the upper value given by Ortofon for that cartridge.
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Well in MM mode the Avid has 48db of gain, which is very high for MM, which is typically around 40db, and the Ortofons tend to measure high output, so what you are hearing could be a mismatch. In which case the only options are to live with it, change your phono pre, or cartridge.
But let's eliminate another possibility before you head down that path. Is it possible that the Avid is just the clearer and allowing you to hear distortion in your setup that the Pro-ject does not allow you to hear? First thing that I would do is double check my alignment, radical stylus cuts like the Shibata and fine line, require exact alignment. And this includes VTA, so I would ask how you are adjusting VTA on your turntables?
A little experiment, and it is a temporary one, is to increase tracking force by .2 to .5 grams (2 to 5 tenths). If the distortion changes in character it is probably your set-up and alignment as the output of the cartridge is still the same. If the distortion does not change, you may have a mismatch. Good luck and get back with your results.
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Another cause of distortion is cartridge mistracking on heavily modulated passages. You can buy a Shure Test Record and test your cartridges to find out how they will perform.
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Lack of dynamic range/headroom on some phono stages certainly exists. Sell the Avid and use the Pro-Ject. The Ortofon mm's have typical output levels.
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