Pearl 3 Burning Amp 2023

[DualTriode]

Do you think the Blue is clipping on loud passages? I’ll have to put mine back on and test it, but my results might not be representative without the 2SK209s.

Hello,

No I do not think that the ortofon Blue M2 MM cartridge is clipping on loud passages.

The thing that I was thinking of is overhead margin. Iff there is a scratch, pop or click, you know some vinyl surface defect the increased cartridge output may push the pre amplifier into clipping. I decided to measure it.

With jumper J2 in place and R22 in the feedback loop;

With 5 mV input the output is 1.65 Vrms @ 0.005% THD+N.

With 29 mV input the output is 9.9 Vrms @ 0.0009% THD+N.

With 30 mV input the output begins to clip, exceeds overload margin.

This is a higher overload margin than I was expecting. 15.5dB

Thanks DT

 

[manniraj]

Some more progress today most of the hardware is done

 

[hbtaudio]

With 30 mV input the output begins to clip, exceeds overload margin.

That is the point!

 

[hbtaudio]

What I would want is 36dB gain to use with a 5mV output MM ortofon Blue M2 cartridge.

Thanks DT

This is also completely correct and a wise decision. Should I describe what could be done to get the P3 to amplify only with +36dB at 1kHz? (But not before Monday evening; if there's a fire, the baton goes back to Jim - he can do that too ;-) ).

Have a nice rest of the weekend,
HBt.


My Pearl 1 only amplifies with a resulting +36dB (1kHz).

 

[MEPER]

Is there any chance a 5mV output cartridge can output 30mV?
E.g. the Ortofon MM is specified 5mV at 1 kHz at 5cm/sec. What I miss it how "heavy" that 1 kHz test groove is modulated?

 

[manniraj]

Output voltage is +/-24.7vdc

 

[vanofmonks]

Is there any chance a 5mV output cartridge can output 30mV?
E.g. the Ortofon MM is specified 5mV at 1 kHz at 5cm/sec. What I miss it how "heavy" that 1 kHz test groove is modulated?

I believe they are worried pops can get that high above average

 

[Mark Johnson]

Rather famous audio guy Tom Holman (Wikipedia entry) published an AES technical paper about phonographic cartridges, their outputs, and related topics. His paper covered output level, ticks, pops, and other details a phonostage designer might wish to explore. Here's a little preview of the Copyrighted first page.

_

 

[Auricle]

That paper is "Open Access" on the AES site...

https://www.aes.org/tmpFiles/elib/20240317/2623.pdf

Free download.

 

[MEPER]

I get this when I try to access the link:

Maybe some that succeeded with the download could add the pdf here (if it is legal of course).

 

[MEPER]

The most "heavy" modulated groove I know about is the 1812 Telarc with the digital cannons.
How much will a 5mV MM output when hitting the loudest "bang" on this record?

 

[MEPER]

 

[Auricle]

Sorry @MEPER I must have posted the wrong URL - I was reading on-line.

Try this - I was just there.

https://www.aes.org/e-lib/browse.cfm?elib=2623

 

[MEPER]

Thank you very much!
I got it!

 

[ClaudeG]

Got it aswell now

Well, the link not working had the merit to make me browse the site this morning, so double thanks to you

Claude

 

[Boydk]

Well..... link worked fine for me.

 

[manniraj]

Any idea of what 3 core shielded cable guys are using for connecting the umbilical cord between the PSU and the Pearl 3 amp boards?

Thanks

 

[DualTriode]

This is also completely correct and a wise decision. Should I describe what could be done to get the P3 to amplify only with +36dB at 1kHz? (But not before Monday evening; if there's a fire, the baton goes back to Jim - he can do that too ;-) ).

Have a nice rest of the weekend,
HBt.


My Pearl 1 only amplifies with a resulting +36dB (1kHz).

As a added note:

When the pre amp begins to clip with harmonics showing up in the 1 kHz FFT the analyzer shows clipping only on the top of the output sine wave. This indicates to me that the clipping begins in the input cascode section of the pre-amp where there is only a single positive voltage supply rail (7815). My P3 started to clip at 9.9Vrms output voltage.

The 7815 +15V and 7915 -15V both are limiting factors to the maximum output voltage and output margin. The following stages, line amp and power amp are also limiting. They have a maximum input voltage before they begin to clip and distort.

Thanks DT

 

[Plott]

Any idea of what 3 core shielded cable guys are using for connecting the umbilical cord between the PSU and the Pearl 3 amp boards?

Thanks

I think in my build I will use VIABLUE EPC-3 Silver balanced interconnect, which has 3 cores.

 

[mhenschel]

@manniraj
45 years ago I used a length of Belden 8403 cable to connect my Leach preamp together.
It still looks good to me.