Looks like a nice project. After decades of making my own (and destroying my darlings again, e;g because the tubes deteriorate in performance; or because my trusted 2SK240 got gate current); then this looks nice.
The Store has none. Any idea for how to get this? Ask Store or Wayne?
The Store has none. Any idea for how to get this? Ask Store or Wayne?
asked to be notified. The listening test by LeovD and others got me in 🙂 There is life there on the other end. At this moment my LP chain is virtually dead (input 2SK240 cascoded to ECC88// ; passive correction).
I've built a Pearl 3 for a friend. It performs as expected (that is beautifully) on my system (Wayne's BA2018, etc), but when connected to his amplifier we can sometimes hear crackling sounds. It seemed to coincide with a bass drum and I suspect the his amplifier is clipping somehow. Can this mean the the gain of the Pearl 3 is to much for his amplifier? It is an Audio Research VSi60, which isn't inexpensive, so what do you think?
We tested with mine Pearl 3 as well to make sure, and the result was the same
We tested with mine Pearl 3 as well to make sure, and the result was the same
The Pearl 3 has much more gain than, for example, a Lehmann Black Cube, which I used before, and I sometimes thought it might be "too much." But if you take the 46 dB gain (approx. 200x) for an MM cartridge with, say, 5mV, you get 1 volt output. The VSi60 has an input sensitivity of 0.47 V rms and a max input of 3,5 V rms.
The entire chain may have too much gain in combination.
49dB (or 70dB) for the P3 => 282x
20dB for a typical build of Wayne's BA2018 => 10x
32.5dB for the VSi60 => 42x
Your VSi60 has over 4x the voltage multiple of a typical Wayne's linestage.
Total system gain is 69dB => ~2820x with Wayne's linestage. That's at the lower of the two P3 gains of 49dB.
As Plott pointed out, you have a max input voltage of 3V5 => You're cartridge only needs to output 1.24mV or so before the amplifier will clip (if I've done my math correctly).
With the VSi60 and a total system gain of 81.5dB your cartridge only needs to output ~0.3mV before the amplifier will clip (if I've done my math correctly).
If for some reason you're running the 70dB gain setting on the P3 that's now... 0.03mV of cartridge output before you run into clipping.
^ I thought of something else after posting, but outside of the editing time window.
I completely forgot to include the attenuation ...
As Plott pointed out - 0V47 is the input sensitivity (voltage to reach rated output at full attenuation).
So with the volume "fully down" - you'll only need 0V47 at the input to reach the rated 50W per channel. Take those values from above and divide by roughly 7 to know just how little a signal you need to have the amplifier at full rated power even with the volume 'all the way down'. If you're between 0V47 and 3V5... I am unclear if it's simply an unclipped signal, but at a higher distortion level than typical for the ratings. They say typical THD at 50W is 1.5%. I may not be interpreting this properly though.
Since you associated it with bass notes, we may guess a slightly lower impedance. The amp may be running out of 'oomph' => can't provide enough current to match the voltage at the speaker's impedance at the bass note frequency. I don't see a spec for a 4R load to provide some hints.
Measuring the voltage at the output of the amp and/or at the output of the P3 will be a good indicator.
I completely forgot to include the attenuation ...
As Plott pointed out - 0V47 is the input sensitivity (voltage to reach rated output at full attenuation).
So with the volume "fully down" - you'll only need 0V47 at the input to reach the rated 50W per channel. Take those values from above and divide by roughly 7 to know just how little a signal you need to have the amplifier at full rated power even with the volume 'all the way down'. If you're between 0V47 and 3V5... I am unclear if it's simply an unclipped signal, but at a higher distortion level than typical for the ratings. They say typical THD at 50W is 1.5%. I may not be interpreting this properly though.
Since you associated it with bass notes, we may guess a slightly lower impedance. The amp may be running out of 'oomph' => can't provide enough current to match the voltage at the speaker's impedance at the bass note frequency. I don't see a spec for a 4R load to provide some hints.
Measuring the voltage at the output of the amp and/or at the output of the P3 will be a good indicator.
Thanks! We'll try to reduce the gain. He's only using MC cartridges so we'll aim for 64 dB for the high setting and 60 dB for the low, and see how it goes. Depending on the value of the resistors I can find in my boxes of parts.
VSi60 uses a digital volume control IC supplied by +/- 5V. Not enough headroom - so it is clipping on large transients from Pearl 3. You could add attenuator (passive volume control) or -6dB pad between Pearl3 and VSi60.
Reducing the gain (changing the feedback) may result in different sound character of the Pearl 3, in my case there was a reducion of the unbelievable liveliness.
Better to use attenuator/pad as @PierreQuiRoule wrote.
I too had too much gain with my tube pre (MC). No overloading though, but volume knob
on.y useful up to 8 o´clock,
Reducing R9 to 1,1K did the trick. Can´t say, that I´ve lost any "liveliness" or other sound qualities with the change.
Still outperforms my former X-Ono clone, both with MM and MC.
In the meantime, some progress. As I wrote, I will use Toroidy donuts and therefore I can't use the psu boards...
So I have to make my own PCBs 😀 I feel like I've gone back 30 years in time, but it's fun to draw PCBs and etch them with Fe(III)Cl
I know, old school, but hey, it's diy 😀
So I have to make my own PCBs 😀 I feel like I've gone back 30 years in time, but it's fun to draw PCBs and etch them with Fe(III)Cl
I know, old school, but hey, it's diy 😀
I know that
you can still wire 'em up to Randy's boards... he says so!
that said there is great satisfaction in designing and manufacturing your own boards. I've no intention of arguing you out of that joy.
you can still wire 'em up to Randy's boards... he says so!
that said there is great satisfaction in designing and manufacturing your own boards. I've no intention of arguing you out of that joy.
Hello Plott,
I also made my own PEARL 3 -boards. One variant similar to the original and a second version for two single opamps.
Both variants are great.
I have used two toroids with CRCRC-filter and regulators (dual mono). Superquiet.
Absolutely fantastic phono-pre!
Thanks again Wayne!
Cheers
Dirk
I also made my own PEARL 3 -boards. One variant similar to the original and a second version for two single opamps.
Both variants are great.
I have used two toroids with CRCRC-filter and regulators (dual mono). Superquiet.
Absolutely fantastic phono-pre!
Thanks again Wayne!
Cheers
Dirk
Hi Dirk,
I didn't want to go that far, I use the forum boards, but the new PSUs were a must.
Cheers
I didn't want to go that far, I use the forum boards, but the new PSUs were a must.
Cheers
I was playing around measuring the pearl 3 with the recently acquired QA403 and I got some weird-a$$ results for distortion. I am aware it's a pretty tricky thing to do generating a superclean 150uV, into a ~50ohms load at it is setup at the moment for the MC pickup.
I played around with attenuators at the input and the output (I run into overload issues), I started at -80dB to -60dB. I tried a few things but I am not really sure what I am looking at. Supposedly there is a protocol setup in QA for measuring riaas but I can't figure out where it is.
Has anyone done it or has any tip or tricks?
I played around with attenuators at the input and the output (I run into overload issues), I started at -80dB to -60dB. I tried a few things but I am not really sure what I am looking at. Supposedly there is a protocol setup in QA for measuring riaas but I can't figure out where it is.
Has anyone done it or has any tip or tricks?
^ Yes. You didn't post your setup or any charts, but two things come to mind that you may be overlooking.
Load the RIAA curve / correction
Pick a load that makes sense
I'd suggest a different thread to get into the details. There are a ton of examples on the QA forum depending on what exactly you want to measure.
Load the RIAA curve / correction
Pick a load that makes sense
I'd suggest a different thread to get into the details. There are a ton of examples on the QA forum depending on what exactly you want to measure.
It was a soothing finger exercise, PSU boards finished:
