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100,000 ohms! [message #13647] Fri, 08 February 2008 22:20 Go to next message
Bill Epstein is currently offline  Bill Epstein
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Registered: May 2009
Location: Smoky Mts. USA
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Clever fellow on Audiogon, rauliruegas, recommends 100k ohms loading for moving magnet carts.

With about 20 hours on the Virtuoso Wood I tried it tonight with some new albums. Excellent sound.

The Woody, BTW, is really getting great. Deep bass, rich mids and airy highs. What the Grado Sonata would sound like w/o the syrupy mids and rolled off highs. Still scared of that proboscis, tho'. Terrified to brush the stylus.

Re: 100,000 ohms! [message #13648 is a reply to message #13647] Mon, 11 February 2008 12:10 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
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Registered: January 2001
Illuminati (33rd Degree)

Since the load sets damping of the coil, it will surely impact the sound. I would guess a higher impedance load would tend to increase output at the stylus resonance and a lower impedance load would decrease it, but that's just a guess. Might make a little more bass with higher impedance and a little less bass with lower impedance. Probably change the overall output level too.

The standard load is 47KΩ and most phono stage amps have this across the input line. Did you remove that resistor or did you add 100KΩ across the line, making total impedance 32KΩ? I'm wondering if the idea is to reduce damping by replacing the 47KΩ load with a 100KΩ load, or if it's to increase damping by adding more shunt resistance, lowering the load to 32KΩ.


Re: 100,000 ohms! [message #13649 is a reply to message #13648] Mon, 11 February 2008 17:15 Go to previous messageGo to next message
Bill Epstein is currently offline  Bill Epstein
Messages: 1088
Registered: May 2009
Location: Smoky Mts. USA
Illuminati (2nd Degree)
On the solid state Nova I set 100k, the last of 17 loading choices! On the Cornet, replaced the input resistors. Gonna switch it back to 47k after I get to 40 hours and check the difference.

Re: 100,000 ohms! [message #13650 is a reply to message #13649] Mon, 11 February 2008 19:07 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18670
Registered: January 2001
Illuminati (33rd Degree)

Gotcha. So the idea is to go up on the impedance. Let me know what you think of the difference between loading at 47KΩ and 100KΩ. Be interesting to listen to a variety of cartridges, each with various loads.


Re: 100,000 ohms! [message #13651 is a reply to message #13647] Tue, 12 February 2008 12:02 Go to previous messageGo to next message
hurdy_gurdyman is currently offline  hurdy_gurdyman
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Registered: May 2009
Illuminati (1st Degree)
I have a Grado Blue I've played with the loading on. Grado used to recommend around 10k-12k ohm for all of them, but changed it to 47k ohm recently. Many think this was to end the confusion caused by the odd recommendation they had had, as the cartridge itself hadn't changed any. Grado doesn't use damping on their carts and tend to rely on damping electrically. Joe Grado often mentioned not liking any damping built in.

I didn't try going higher on mine, but did take it down to around 15k ohm. It made a slight reduction in highs (and I mean slight) but did sound a bit cleaner (as in less edgy). Again, the difference was slight. I left it at 15k ohm, as minimizing as much listener fatigue as possible throughout the system is a high priority for me, as I have the stereo on all day typically.

Dave


Re: 100,000 ohms! Uhhhhh, maybe not. [message #13652 is a reply to message #13650] Sat, 16 February 2008 23:34 Go to previous messageGo to next message
Bill Epstein is currently offline  Bill Epstein
Messages: 1088
Registered: May 2009
Location: Smoky Mts. USA
Illuminati (2nd Degree)
I've been feeding the Wood a steady diet of Jazz and 100,000 ohms was sounding good.

Tonight, with about 40 hours on, finally, I played the Saint-Saens 3rd Symphony. Loud. With both amps, the 45 and a yet-to-be-named 50 watt 6SN7/KT-88 P-P. Not both at the same tyme, of course

Horrible! Que Barbarida! Veiled,confused and congested. $29 Radio Shack mics weren't used by RCA so I suspected something wrong.

That, after visiting with Steve Brown today and we agreed how good the higher impedance was.

Switched back to 50,000 ohms and Et Viola, verrr nice. And that's where it will stay.



Re: 100,000 ohms! Uhhhhh, maybe not. [message #13653 is a reply to message #13652] Sun, 17 February 2008 09:11 Go to previous message
SteveBrown is currently offline  SteveBrown
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Registered: May 2009
Grand Master
Well, very interesting. On the preamp I'm building right now, I actually have it switchable: 47k, 100k and 1M. So I can try different settings. I'm betting different music may work better w/different cartridge loading, but not sure. By the way, why 1M?? Well, I have a Grado Sonata that likes a 47k impedance but being a 0.8mv cartridge, I have to use a step up transformer for it. Since the primary impedance the cartridge sees is reflected from the secondary, and in this case stepped down by a good size factor, starting w/1M on the secondary will give me closer to the loading the cart wants to see. At some point I'll try to build a hybrid phono stage (FET + tube) to eliminate the need for the step up transformer. Oh, and the pre that is under construction should be fun, it is an all octal pre based on the Octal Coronet (Hagerman) design, then going to a 6SN7 line stage. Even the rectifier is an octal. I've tried octals (6SL7's) in the phono stage before and they can be very microphonic, but I think I've got that licked this time by using a Russian equivelent to the 6SL7. In some tests I've done I can rap the glass envelope with a pencile while it's working and not get any microphonics. Sounds great so far, too!

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