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Cartridge loading plugs

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tg [RIP] View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tg [RIP] Quote  Post ReplyReply Direct Link To This Post Posted: 27 Mar 2013 at 2:11pm

Juan,

thank you for sharing your experience with this method of tweaking the cartridge load.

Your findings with the DL-304 mirror my own findings with the DL-301 II as to their effect.

I would question the 170 ohm (typo perhaps ?) since my calculations yield 270 ohm as the required parallel load with 840 for a 204 ohm equivalent load.

IIRC oldagetraveller runs a DL-304, perhaps he might like to try this load too.

Always good to find inexpensive tweaks that yield such positive results.

Have fun,

Tony G




Edited by tg - 04 Jun 2016 at 8:02am
Tony G
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Juan Pyrrho Quote  Post ReplyReply Direct Link To This Post Posted: 27 Mar 2013 at 2:39pm
You are dead right about the resistor values. 
I got lazy and quoted them from memory rather than checking them out properly. Very remiss of me,  
As the americans say,  " my bad .."

well spotted by the man from down under.

regards from a cold & miserable East Dulwich, south London.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote oldagetraveller Quote  Post ReplyReply Direct Link To This Post Posted: 28 Mar 2013 at 12:41pm
"IIRC oldagetraveller runs a DL-304, perhaps he might like to try this load too"

Yes, he does.Smile It's actually in use at the moment, on my Tarantella, through Elevator and Reflex M. I'll get hold of some 270 Ohm resistors and give it a go. It might be a few days - there's no way I'm retiring to the garage, in the cold weather we're experiencing at the moment, to rev up the soldering iron!Big smile
Peter

P T- LPT/RB300/G1042, Pink Triangle Tarantella/Nima/Ortofon 2M Black, SL1210II, Naim CD5, NAC112, NAP150, Flatcap2, Proac SC1, GS SoloUL,GS Accession , Senn HD250 & HD540.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tg [RIP] Quote  Post ReplyReply Direct Link To This Post Posted: 28 Mar 2013 at 2:30pm

FWIW, I use the 270 ohm plugs with 1K on the front panel for 212 ohms effective with the DL-301.

It has just returned from being re built with a ruby cantilever and line contact stylus and is sounding stunning.

regards from hot and sultry (0130 hrs and doors open and no shirt on) Dulwich Hill, Inner southern Sydney.  Nearly cool enough now for sleeping and the planes have all gone to bed Smile



Edited by tg - 04 Jun 2016 at 8:03am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Fatmangolf Quote  Post ReplyReply Direct Link To This Post Posted: 26 Nov 2017 at 12:11pm
This thread focussed on resistor loading and I wanted to expand it to capacitative loading if that's okay with you Tony (tg)? It struck me that we could use the splitter and loading plugs you describe above for small capacitors too. I can take this into a new thread if you prefer?

Jon

Open mind and ears, whilst owning GSP Genera, Accession, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Fatmangolf Quote  Post ReplyReply Direct Link To This Post Posted: 26 Nov 2017 at 12:29pm
The back story. In other threads Graham explored the impact of changing the capacitance formed by the tonearm leads and internal components of the phono preamp. For MM this creates a peak that extends the audio frequency response to 16kHz or so. For MC it can be used to reduce the level or electromagnetic signals picked up by the cartridge.

For MM I bought a Genera preamp kit from Graham Slee products and really enjoyed the sound it gave me compared to other preamps I owned. I fitted internal switching that allowed me to adjust the capacitative loading and wrote about this elsewhere on this forum. As Graham advised the choice of capacitator type made quite a difference, I really liked the Polypropylene type he suggested - Evox PFR. The Accession MM preamp I now have included external dip switches to change the same loading and probably uses the same parts to even better effect. For MM this is 100pF and 220pF, i.e. pretty small values.

At this point I am interested in MC loading. It was a revelation to me that a much higher value than I associated with cartridge loading but the 4.7 nF Graham recommended seems to have improved my records' sound when played back. It had never occurred to me that the LC combination could be used as Graham did, to filter out problem radio and data signals so these didn't interact with the audio. Same formula Fr = 1 / (2 Pi SQRT(LC)).

I don't have a Spice circuit simulator but the forumula above and R = SQRT (L/C) are enough to explore some options. As the manufacturer of my MC cartridge doesn't publish its self induction (L above) what I know it that my version has an internal resistance of 7 ohms, which is Rdc not the loading R above! Crudely comparing Rdc and L for other cartridges I concluded mine could be in the 10 to 20 uH range. Graham suggested a similar cartridge at the upper end of my gestimates, a good sign my figures were reasonable.

To test the impact I fitted a pair of 4n7F capacitors inside my Elevator EXP. After allowing a day or two for the unit settle down under power I really liked the sound and wanted to explore further on the loading. To get a resonant peak in the 300 kHz range Graham has simulated my optimal loading would be a lot higher that the 4n8F I have now. From the Fr formula about the capacitor would be about 10x higher i.e. more like 50nF or 0.05 uF. I am interested enough to explore this and have an unused third switch on my EXP that accommodate this alongside the existing switched resistor options. To avoid powering down I thought of using phono Y-adaptors as Tony described here. I still have the bits from when I tried this with my Rega Exact feeding another manufacturer's preamp, think Oxbridge you'll know what I mean.

In 2010 I picked up an article on cartridge loading that was about MC's and step up transformers. I filled it away on a hard drive and rediscovered it as few days ago. The second half of the article uses the Fr formula above to get an MC peak in the audio range, using capacitor values around 1uF which was an eye opener. It is about 400 times higher than the loading I now! I am pretty happy with the treble response of my Phoenix so I won't be going that far, but it does show what could be done. It is Graham's RFI reduction I am interested and the heterodyning he has identified makes sense to me.

Now I need to find some reasonable sounding capacitators in the 10-50pF range and work out how to fit them into phono plugs with some shielding!
Jon

Open mind and ears, whilst owning GSP Genera, Accession, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tg [RIP] Quote  Post ReplyReply Direct Link To This Post Posted: 28 Nov 2017 at 3:36pm
Go for it Jon, I will follow your experiments with interest. 
This does seem the most pertinent place for such.

Tony G
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