Pass XP-17 and Hana ML loading question

Of course, try 47K; nothing is going to blow up. But it’s most likely that the difference in sonic character between 15 and 17 is due to circuit differences, not load. 

@lewm 

Yes, circuits are diametrically different that is a fact, but loading the cartridge should have same effect on cartridge performance , sound of it at least on the dynamic level should be similar to the loads on 15 at least in the characteristic of the sound. what I'm getting on same load is half of bottom end. Does it make sense to you ??

As Atmasphere is fond of reminding us, the phono load resistor is for the phono stage. Anyway, in my personal experience of playing with load resistors, the value makes very little difference. Of course, there are others who have had contrary results. So try it and let us know.

Ok guys, so far all I can tell you is that you weren’t squeezing top of the performance from the XP17 if You have it set at 66db of gain and 100ohms load.

I have run my Hana ML through that setting it seam like sound was super blunt.  Then I tried 76db of gain and 350 ohm load. It was good but slight oversteer on sopranos. So I switched it back to 66db but kept 350 ohm load, it was great sounding but bass was weak and not distinctive, so I keep 66db of gain and loaded with 1Kohm ! Now things are getting serious :-) next step will be 47Kohm ! And I’ll keep you posted ! I wish I could try Hana Unami Red to see what that thing can do! Well one day I’ll get it and let you know how it goes. I’ll let you know when I squeeze last drop and tell you how much I improved sound. Still thinking  about Unami Red or Blue any comments from owners ?

@lewm Regarding loading resistance please read my comment above, my experience shows me it does make difference. 

Ok. Then play with the values. You can’t damage anything.

well when I load Hanna ML on XP15 with 47k the bass was amazing, but top end and half of mid was nonexistence. so naturally I will load 17 with 47k and see what will happen.

If the XP17 is brand new, it can take some time to break in.

There’s absolutely no way that loading an MC with 47K should eradicate treble. That’s very odd.

@testpilot  I don't think I have 100 h on the unit yet so yes breaking period is understandable 

@lewm  I understand your doubt  but all im saying thats the facts that I can hear.

Now I've tried also setting  of XP15  at 1K ohm and it was better than 47K so I consequently started to drop the resistance first to 850 it got better than 500 better yet than 430 it got better yet so I continue down to 350 better 333 better 250 no difference 200 worse than 250 so I start adding on and with that type of yoyo test I saddled for 333 ohms load that sounded the best to my ear.

You are not the only one who reports the result that changing the load resistance by 20,30, 40 ohms in the already low resistance region (say, below 1000 ohms) makes a critical difference, with a LOMC cartridge. All I can say is, I never have understood such reports. It runs completely contrary to my experience. in my experience, yes, there is a very slight difference between very low load resistances and 47K ohms. However, the differences are mostly that the highest resistance sounds a little more lively to me. I certainly have never heard a difference between say 200 ohms and 250 ohms With any low output moving coil that I have ever owned. This is certainly not to say that you are wrong or misguided. It probably has something to do with the design of the phono stage, although I confess my experiences are the same with any of three or four phono stages that I own, some of which are solid state and some of which are tube Types.

There is one exception:  As you may know, it is optimal for the ratio between the internal resistance of the cartridge and the input impedance of the phono stage (which is largely determined by the phono load resistor) to be related by a factor of 1:10 or better.  For example, for an LOMC with an internal R of 10 ohms, you want to load it with at least 100 ohms or higher resistance (which is why even 47K ohms is fine). The reason is as that ratio gets lower than 1:10, you begin losing more and more of the cartridge output (signal voltage) to ground.  So the coupling becomes less and less efficient.  But if your phono stage has an excess of gain, that wouldn't matter so much.  What also happens however is that as the ratio gets lower, you begin to preferentially lose treble, because of any capacitance at the phono input stage.  (All gain stages, both tube and solid state, present a tiny capacitance at their inputs, unless the input is a cascode. There is also cable capacitance.) And the sound gets dull. (Which is why I was so surprised that you say you lose treble when R goes to 47K ohms. Should be the other way around.)

I don't have much experience with phono stages 35 years ago I had integrated amp that had dedicated phono input.  So far I tested Schiid Mani and Mani2 they are ok sounding but noise level was outrageous at 66db gain. Next I got to deal with XP15 and now with XP17. All I know about it is what I'm learning by dealing with the issue now.

Yes, circuits are diametrically different that is a fact, but loading the cartridge should have same effect on cartridge performance , sound of it at least on the dynamic level should be similar to the loads on 15 at least in the characteristic of the sound. what I’m getting on same load is half of bottom end. Does it make sense to you ??

@ssg308 Loading the cartridge causes the cartridge to have a stiffer cantilever as you are asking it to do more work. There really should be no need for this anyway since the main reason to use a ’loading resistor’ is, as @lewm pointed out, its really for the benefit of the phono section.

The cartridge is an inductor and the tonearm cable has capacitance. Since they are in parallel, an electrical resonance is created. With the Hana its quite high- 2-3MHz. That’s Radio Frequency territory and so when that resonance goes into ’excitation' (in radio parlance) its RFI being injected into the input of the phono section!

Some (most) phono preamps don’t like that and won’t sound right until the RFI is eliminated. You can do that by placing a resistance in parallel with the resonance, detuning it and thus preventing RFI. Hence the loading resistor.

Always try no loading and give the cartridge enough time to break in. Also make sure your setup in the arm is a good as it possibly can be.

If the phono section is properly designed (IOW the designer understands the implication of an inductor in parallel with a capacitance; electronics 101 FWIW...) then that will be the best you can do. Loading the cartridge will simply cause it to lose high frequency tracking ability as the cantilever gets stiffer and may cause the arm’s mechanical resonance to be outside the ideal 7-12Hz range, impairing tracking.

@atmasphere Wow you changed my perspective how I look at the problem ! great let me read it again so it can sync in  and I'll try to experiment a bit and try to load it with different resistance and see how it effect it. BTW I  tried 47k and it sounds terrible.

Have you tried a 47K ohm load with any other typical LOMC cartridge, ever, with either of the two Pass phono stages?  What was the result?  Thx.  Also, can you define "terrible"?  Do you mean that the treble was rolled off or missing, as you mentioned earlier?

No, unfortunately I own only one MC cartridge Hana ML , my other cartridge is MM Ortofon 2M Black   

And what I meant by saying "terrible" was, sporrans and mid got clipped about 30%  while bass got big but hollow and muddy no definition at al just slams of senseless sonic boom,  and on top of that when record ended and I raised arm I heard harmonics between speakers and cartridge. I went bac to 1k setting and now over 4th weekend I'll experiment with all settings I have between 500 ohms and 1k to see if there is anything else I can squeeze out of the system.

One remote possibility: when you set load at 47K, the two channels are out of phase with each other. That would have to be due to a glitch in the internal wiring of that resistor, since other loads are at least functional. I would consider sending the XP17 to Pass for inspection. If there’s some other problem, they’ll find that, too. Because believe me, there is a problem somewhere.

And what I meant by saying "terrible" was, sporrans and mid got clipped about 30%  while bass got big but hollow and muddy no definition at al just slams of senseless sonic boom,  and on top of that when record ended and I raised arm I heard harmonics between speakers and cartridge. I went bac to 1k setting and now over 4th weekend I'll experiment with all settings I have between 500 ohms and 1k to see if there is anything else I can squeeze out of the system.

@ssg308 Check your phono cartridge wiring to make sure the connections are right. If you got one channel backwards it would sound exactly like this!

Which is what I said, too. But it can’t be at the cartridge because he reports relatively good results with all other choices of load R. Which is why I suggested there may be a phase error incurred in relation to wiring of the load selector switch, when he sets load to 47K. Or something like that is reversing phase in one channel, only when 47K is selected.

@atmasphere 

I can make sure it is connected correctly, How would I know what color on cartridge is corresponding with +post  and what color is what channel ? where I can find diagram ?

@lewm 

If you think it is possible I will call to Pass labs and have conversation with the tech.

Both amps seam to act the same way when comes to the 47k load.

Anyhow I'll report back what Pass has to say about it. 

Until now, you never revealed that both the XP 15 and the XP 17 had this sonic character when you set the load to 47K ohms. Since you used the term “amps”, is it correct to assume that you mean both phono stages? If so, I am stumped, because it is highly unlikely that both phono stages were miswired at the factory. So by all means call Pass labs. I would be interested in what they say.

Also check the leads at the cartridge as Atmasphere suggested and even though you say you’re relatively happy when load R is 1K or less. So this is a real shot in the dark. Color code as follows:

red= right channel hot

green = R channel ground

white = left channel hot

blue = L channel ground

Also check that your speakers and any subwoofers are wired in phase with each other, meaning left vs right.

@lewm 

Ok I verified sound track from cartridge to the "phone stage pre-amplifier"- (I think that is correct name of it)- all good that way.

Yes they both have similar sonic characteristics, and after conversation with Pass tech support I realized that they are designed to handle most cartridges on the market, even those hard to load. In matter of the fact they are easily can overload any cartridge.

So what I understood was, just because unit can do it it does not mean that it will work with cartridge+tone arm+ connecting single post wire, exactly same way.

They are design to be versatile so it means you need to do your home work with setting it up. Sure you can go by suggestion of cartridge maker or owner manual but last decision how it sounds is ultimately owners choice. There are people who are happy with 66db at 100Ohm load, some are like me and looking for best possible performance. 

1k is good 500 ohm not bad lets see how 825 ohm sounds like and I'll get back to you.

I don’t quite understand your last post, except it seems you’ve checked the cartridge and speaker wires and the two channels are NOT out of phase. Do you understand that point?

the rest of your last post eludes my grasp. The issue I focused on is why the 47K ohm setting sounds so uniquely awful. There shouldn’t be much if any difference between 500, 825, and 1000 ohms load with your cartridge and either phono stage. Which is to say they should all sound fine and not much different from 47K ohms.

well I have no idea why they acting like that but to me it's a new endeavor with TT and cartridges and phono stages... I guess I'll keep working on it till I'm satisfied. maybe Hana ML is not the greatest match to my tonearm ? would that make such a problem. ?

Again, you’re relatively happy with load resistance other than 47K ohms, so a mismatch between cartridge and tonearm is not high on my list.

I would conclude that, MC cartridges (at least in my case Hana ML) and XP15 works with loads anywhere between 100-333 ohms sounds the best,  and XP17 will work the best between 100 and 1000 ohms for optimal best sound. 

OK.

Don't know in this helps, but I have the XP-17's distant ancestor, the XOno, and I listen at 1000 Ohms with the Hana ML. I've tried many settings from 50 Ohms to wide open, and 1000 was hands down the best, for me. 

paul 

what was the minimal load value that it sounded acceptable ?

I load mine at 47K and it works great.

As you decrease the load it sees, two things happen. The first is the output level decreases especially as the load value approaches that of the cartridge itself but 100 Ohms will have no effect at all in that regard.

The second of course is that the cantilever gets stiffer, less compliant, since you are causing it to do more work.

Depending on the tonearm used and how well the phono section reacts to RFI, the value a person arrives at will be different. So I would not rely on other's experiences without knowing the provenance.

in my case 47k is just not working, believe me Iv'e tried. 

@ssg308 I don't doubt you although I am a bit surprised. Others have reported Pass Labs phono sections as not needing 'loading' ('detuning' is a more accurate term) resistors. Simple decrease the load till its starts working... I'd start with 1000 Ohms and work my way down.  

@atmasphere 

well that is exactly what I did the only difference was I started with 333 ohm than jumped to 47k and back down to 100ohm just to go back to the 1k that is where I decided  is the best setting for my setup.

@ssg308 1000 Ohms is so high a value it can't be affecting the cartridge at audio frequencies at all. So this has to be how the preamp is reacting to RFI.

@atmasphere

I have 2 different phono stages from same manufacturer and they both act different in same configuration of the rest of the gear. they producing best sound with loads between 100-333 ohm and XP17 improves sound up to 1k 

This makes sense. Different designs do act differently when subjected to RFI.

it is what it is, I make it sound te way I like it so I'm not gonna debate anymore why is it like that.