Tube Preamps...I'm sold

Tooob : Sorry T/P > Tube Preamp. Thanks for reading and responding.

Crem1: Your advice is good for someone totally focused on LP playback. Unfortunately, the SP-10 as a line stage for other sources is mediocre at best. Tubed line stage performance has come a long long way since then.

I ran with the SP-10 II for 8 years from the mid 80s-90s and loved it. But the LS5/PH2 pair that replaced it was far far beyond the SP-10 for both LPs and CDs. Finally CD playback was tolerable! And even though the PH2 was solid state, this with the LS5 had the incredible dimensionality of the SP-10 but with far more extended frequency extremes and without the noise level. I never would have believed the PH2 could do this ..... but it did.

Steve Huntley at GNSC does some incredible rework for the SP-10 but this can be costly when you're all done. I cannot imagine tolerating the stock SP-10's weaknesses after hearing the many refinements in products over the last 10 years. But for LPs anyway, the GNSC SP-10 rework is a totally different sonic performer altogether. I know a vinyl guru in Canada who has one and he loves it.

Just recently I got an ARC MCP-33 to support multiple arms/cartridges. The MCP-33 came out after the SP-10 to support MCs with other ARC preamps like the SP-8 and SP-6 which only supported MM cartridges. I understand that the MCP-33 and SP-10 have very similar MC input design.

After some major parts updates and IEC connector to this MCP-33, the performance is outstanding. I don't know how much improvement was gained by the various Dynamicaps and Vishay resistors, but changing from a stock power cable to something like a Stealth Dream power cable is HUGE. This alone should be done to all older tube gear with attached power cables. And this modified MCP-33 is very quiet .... something I was concerned about when I took on this MCP-33 modification project.

I have been playing with this MCP-33 into an Aesthetix Io Signature set at 56db gain....and comparing to the Io Sig. on its own at 68 db gain. Both units render the 3D of the music incredibly well. But it is clear there are hints of the SP-10's rolled-off frequency extremes, primarily in the bass, with the MCP-33. Perhaps beefing up the power supply would help things here. I might just have Steve Huntley take a look at this one of these days.

For someone that has a decent full-function preamp but perhaps does not have enough gain for their favorite MC cartridge, or they are looking to bring on some tube magic to their system, an MCP-33, RAM RM-4 or Counterpoint SA2 might be a perfect and less costly solution. Unfortunately the added cost of an IC and a PC, both must be at the top of their class, takes the price quite high. And then the quest for the perfect set of tubes begins and this too can add up. Top-tier performance does not come cheap.

John

John: I agree the AR SP-10 needs some modification to bring it to the MK II status. My SP-10 MK II was modified by Gary Muffely , a fellow who knows more about circuits than anyone I have ever met , and at my age that's saying something . Sorry, I can't say that I have had the same experience as you. My "10" was carefully re-worked and select tubes replaced the factory set. Images appear to float in the air... Of course my set-up may account for the experience. In real $$$$ terms one would have to spend 12K to duplicate the "10". You are on the Mo'Money " Top-tier performave does not come cheap" .

Jafox :
After sliding into the slumber position for the night , my foggy-bottom mind woke me up. One tweak, that I failed to mention, that has an impact on what you hear , I have performed since The Absolute Sound wrote of it in '93 is shooting a tad of DC current into the "10's" imputs. Nothing extreme, just using a Mc demagger as TAS outlined. That smack of DC helps to eliminate AC eddies that form around the leads of almost all compoments within the case. The sound is transformed as is the unit. XLO also put out a CD that roughtly producees the same results. The process is performed every month or so 5 seconds on 5 seconds off via a interrconnect. Remarkable results for tube preamps. Enought ... Golden Slumber Time.

Crem1 - Thanks for the tip on the MC demag device. I never heard of this process. Now I have the itch to try.

I always wonder where my SP-10 might be today ... no doubt it has changed hands a few times since I sold it in 95. You describe this very well as portraying floating images. This is why it took me so long to find a product that had the SP-10 magic but then went to the next level of refinement. It was no surprise that it took the LS5, a return to an all-tubed line stage since the SP-10 a decade before, to bring back that musicality. All of the ARC "hybrid" designs from the SP-11 through the LS2 were too sterile for me.

As for SP-10 MK II status, as I recall, one can tell of this by seeing 2 pairs of 1 or 2-watt resistors, each pair in series and sitting on the board in a teepee fashion. I have since forgotten what the benefit or "fix" that came with the MK II update.

I would be reluctant to do any serious circuit design changes but rather simply focus to replace passive components in "critical" areas. But I would also be aware that some of the musicality/dimensionality might be lost for the sake of greater resolution and detail with "refined" passive parts. Getting both of these improvements would likely require a change to a different product.

I made one slight change in the MCP-33 to allow for the MC load to be as high as 200 ohms instead of the maximum 100 ohms. The MCP-33 owner's manual talks about this as a possible limitation of this product for some cartridges. And ideally my Clearaudio and Koetsu cartridges perform their best at a 500 ohm load but they work very well with the MCP-33 with a 200 ohm load...even the 100 load. I am reluctant to change the one resistor value any higher as this could affect any number of critical circuit parameters. And I would be reluctant to do anything similar in the SP-10. Having a circuit guru helps a lot.

John