Clipping Preamp?

[Delkat]

I thought I’d run something by the group. I recently got a second tonearm mounted on my table and am running an Umami Red (0.4mV output) on it. The main arm (Kuzma 4 Point) is running a Verismo (0.2mV output). Both are running into an AR Ref 3SE using the high gain path (73db) and loaded at 100ohm.  Then going to a Ref6SE pre and to M5-HPA into Kentos. 
 

I just received the new White Stripes UHQR and the opening track 7 Nations Army was just begging to be played loud. I started with the Verismo and cranked up the volume control until the SPL kind of flattened out. It seemed like somewhere in the high 50s (0-100 range) was where it was no longer increasing in SPL as I continued to go up on the volume so I figured, OK, I’m probably clipping something and need to back it down, although there was no noticeable distortion. 
 

Next up was the Umami Red and I reached a similar point on the volume, albeit a bit numerically lower as I was starting with double the output voltage on the cartridge and always have about 6-8 clicks lower on the volume knob to get the same SPL. Only this time I could achieve an overall higher SPL using the Umami compared to the Verismo. 
 

My thoughts are that I must be limited by the Ref6SE pre as it’s receiving a lower signal voltage from the Verismo through the 3SE and must be clipping as I go up in volume reaching the max gain it can output to the M5s whereas the Umami’s higher voltage coming into the 6SE is resulting in a higher output voltage at max gain thereby achieving a higher SPL. I don’t think the M5s are clipping because they achieve the higher SPL using the Umami path. 
 

73db is a lot of gain and should be plenty for the Verismo so I’m a bit surprised that I hear this difference in max SPL. Any other theories?

Thanks

[Richard Vandersteen]

Try lowering the gain in either the 6SE or Phono because you could be overloading the volume control in the 6SE.  RV

[TomicTime]

and get an SPL meter 😉 …..

[Delkat]

I’m not aware of a way to lower the gain in the 6SE and the phono only has a choice of 51db or 73db. I guess I could try running the Umami with 51db gain setting to see if I get a similar result as what’s happening with the Verismo where I’m not able to get enough SPL no matter how high the 6SE volume is set. 
 

I do have and SPL meter but the contrast was so stark, I didn’t feel the need to use it.  I can try that this weekend. 
 

I did notice a similar situation where I have 2 DACs running through the 6SE, a Bluesound Node and a Tambaqui.  Playing the same track switching back and forth, I can get a much higher SPL on the Tambaqui but it has a variable gain setting for 0.6V, 2V and 6V output. It is set at 2V. I can’t find a spec on the Node but I’m assuming it’s less than the 2V on the Tambaqui. 
 

Again, my thought is that if I am going in to the 6SE with a lower voltage signal (from Node DAC or  Verismo/Phono), I’m using its maximum gain and still not getting a high enough signal out to the M5s to achieve the same SPL they are capable of driving as proven by using the higher voltage signal from the Umami/Phono (and possibly the Tambaqui) which I assume is getting the same amount of gain through the 6SE resulting in a higher input voltage to the  M5s. 
 

More experimenting to come. 

[Richard Vandersteen]

The M5-HPA has a gain of 25.  RV

[TomicTime]

the balanced input gain on ARC products is MUCH higher than the SE ( and also imo sound much better ), i assume your NODE is SE output ? i was being snarky on the spl meter as i misunderstood your comment about max volume at 50… i should have asked more ?

[Richard Vandersteen]

Would be 6 db difference between SE and Bal.  RV

[Delkat]

Yes, using all balanced in and outs except for the Node is going in to the 6 SE via single ended. 

 In speaking to the AR people, they really don’t recommend cartridge output less than about 0.3mV for best results.  My Verismo is 0.2mV which using the 73db gain setting would result in a 0.89V signal going into the 6SE compared to a 1.79V input signal using the Umami.  Adding the 12db gain spec on the 6SE would produce a 3.54V output to the M5s using the Verismo and 7.13V with the Umami.  Maybe the 3.54V into the M5 is not high enough for optimal performance?

Thanks

[Richard Vandersteen]

25 dB gain is very common (2 volts will drive the amp into clipping) but .2mV will require more gain in the phono stage or a transformer.  RV

 

 

[Delkat]

Ok, that’s very helpful Richard.  
 

Now I’m wondering how the cartridge manufacturers spec the output voltage. It sounds like they use some stylus displacement velocity such as 5cm/sec for the rated output voltage so it’s not a peak voltage. So with the 73db of the 3SE phono stage plus the 12db of the 6SE pre, I should be getting about 3V to the inputs of the M5 at the 5cm/sec stylus velocity and much higher for the peaks. Obviously the volume control attenuates that signal going out to the M5 but it would seem there’s plenty of signal available. 

[TomicTime]

: Kuzma CAR 40 > ARC REF phono 2SE > ARC REF 5 SE > Vandy HPA -7 amps…..

Maybe your cartridge dealer can lend a SUT ? …..

Best to you

Jim

[TomicTime]

my chain above w ,3 mv Kuzma… no issues…

[Holmz]

On 10/12/2023 at 1:46 AM, TomicTime said:

the balanced input gain on ARC products is MUCH higher than the SE ( and also imo sound much better ), i assume your NODE is SE output ? i was being snarky on the spl meter as i misunderstood your comment about max volume at 50… i should have asked more ?

I thought that the balanced was the 6dB higher output, but on say amp inputs then the gain is lower on balanced versus SE ???

[Holmz]

22 hours ago, Delkat said:

Ok, that’s very helpful Richard.  
 

Now I’m wondering how the cartridge manufacturers spec the output voltage. It sounds like they use some stylus displacement velocity such as 5cm/sec for the rated output voltage so it’s not a peak voltage... 

The 5cm/sec would be peak voltage.
Anything with no music happening, then there would be 0cm/sec…

 

On 10/10/2023 at 3:49 PM, Delkat said:

My thoughts are that I must be limited by the Ref6SE pre as it’s receiving a lower signal voltage from the Verismo through the 3SE and must be clipping as I go up in volume reaching the max gain it can output to the M5s

I think it could be too much gain…

But I am somewhat confused, but ignoring not comprehending the opening post…
If the signal is railed coming into the preamp, then there is no 12dB of gain there. It is just clipped. 
However then it should be loud as all buggery.

It could be clipped at the preamp input and then the preamp is turned down to the right volume for the speaker to make the desired SPL.

As a kindergartner, if the preamp is not sitting around 1/2 way up, and it is sitting way down near zero, then remove gain before it, so that the preamp has something it can be doing... other than just doing massive attenuation.
Sometimes it needs to be cranked up even more.

If you are already at the 73dB setting, then the only other direction to go with a choice of 51dB and 73dB… seems obvious.
What happens at that setting again?

Is it way too quiet?

[Delkat]

Definitely not too much gain. If anything not enough for the Verismo/0.2mV.  I think the SUT is probably the way to go with the  Verismo. At a standard listening volumes the 6SE setting for the Verismo is around 38 and 30 for the Umami. Umami gets to max SPL around 55 and then flattens. Verismo around 60 but max achievable SPL is lower than Umami and I really don’t know why. That’s the reason for this post. 
 

5cm/sec is not max voltage. It’s just a standard for spec’ ing a cartridge output. There are test tracks with 20cm/sec displacements.  
 

The gain is 6 db lower on SE inputs through the Ref 3SE and 6SE.