Solid State replacement for AR SP8 Preamp

jimbones · September 27, 2012, 06:12:23 AM

I have owned a Audio Research SP8 preamp for many years. Still sounds OK, albeit a bit noisy. If i wanted to replace it with something solid state, lets say something on the udes market, how much would my entry point be in dollars? Any suggestion on what to buy. I am in no rush to buy and will be patient in looking for something. If it doesn't make economical sense I'll just stay with the SP8. I'm not sure I would even sell it. Mught just keep 2!

richidoo · September 27, 2012, 07:10:25 AM

SP8 came with Sovtek 6922 which are expected to last 5000 hours in SP8. If you feel that the pre is noisier than it has been before, then it could be worn tubes. If you play it 40 hours a week then 5000 hours goes by in only 3 years. If you play it only 8 hours a week then 12 years. But tubes worsen gradually, not suddenly. They can still measure within spec but start degrading sound quality. Noise is usually the first sign. Signal strength, tonal purity, dynamics also fade, but this is less noticeable. When you replace the tubes the preamp will sound much better in every way, not just less noise. My fav 6922 tube is Matsushita from 1970s.

Now tell me that you already replace the tubes every year.

Good SS preamps that can make music like AR tube preamp will cost more than the AR. If you want to upgrade, look at the new ARs, deHavilland. In SS I would look at Parasound JC2, and Pass. The new Classe preamp is supposed to be very good. I think it is digital?

rollo · September 27, 2012, 08:40:28 AM

The SP-8 is a classic circuit design. I would talk to AR and find out how much they want to bring the Pre back to life. Besides the Tubes Caps go over time.
The 6922 for the AR are Matsushita. I use them with my AR Amps.
A SS replacement will be a tough find.

charles

tmazz · September 27, 2012, 04:05:11 PM

Quote from: richidoo on September 27, 2012, 07:10:25 AM
SP8 came with Sovtek 6922 which are expected to last 5000 hours in SP8.

Rich, you may be thinking of the SP-9 which has only two 6922 tubes. While the SP-8 had a pair of 6922s it also had six additional 12V tubes of varying types depending on what revision level the pre was.

And by the way, I do change the tubes in my SP-9 every year. It is my New Years Day ritual. Easy to do with the SP-9, but it gets a little pricey with all the tubes that are in the 8.

richidoo · September 27, 2012, 05:28:52 PM

Yes, sorry, I looked at a LS8 review, which mentioned SP8, but the two 6922s were the LS8. Thanks

tmazz · September 27, 2012, 06:07:25 PM

Quote from: richidoo on September 27, 2012, 05:28:52 PM
Yes, sorry, I looked at a LS8 review, which mentioned SP8, but the two 6922s were the LS8. Thanks

But your point is still valid. The noise could be coming from old tubes. Its just a bit more complicated to find with a larger amount of tubes in the unit.

As for replacing the SP-8 keep in mind that the SP-8 was an early 80s design and as such still had a bit of a lush tube sound to it. Not that this is in and of itself a bad thing, but that type of sound will be difficult to replicate with a SS unit. So if you want to just replace the SP-8 with a modern SS design that is one thing, but if you are trying to replicate its sound that will be a tall order.

richidoo · September 27, 2012, 09:10:35 PM

We'll have to wait to hear back from Jim, but they might be old tubes throughout, which makes the fix easy. The only thing worse than 1 noisy tube is... you guessed it... 8 noisy tubes!

jimbones · September 28, 2012, 06:07:55 AM

I'm Back.

Tubes are new (less than 300 hrs on them). I don't listen a lot so the tubes last a long time but I do replace them periodically. When in doubt, I just change them.

I am not looking to replicate the sound of he SP8. I'm looking for quieter and more detail, but not hard sounding. Back in the day when I bought the SP8, SS was a bit harsh. I am sure there has been improvement.

Oh, BTW, I changed out the caps in the power supply (Parts directly from AR).

Thanks,
Jim

BobM · September 28, 2012, 07:23:45 AM

May I ask why SS? Why not a more recent tube preamp? The line between tube and SS is less obvious than it used to be. Both can be very clean, detailed and beautiful these days.

jimbones · September 28, 2012, 08:04:26 AM

Well the reason I state SS is that I have a hard time believing that a tube preamp would be as quiet as SS. I did hear a SS preamp in a store a few months ago and was surprised at how far SS has come. I also want to prepare for the day I can't get tubes or they might become so expensive that it becomes cost prohibitive.

BobM · September 28, 2012, 08:58:42 AM

Of the SS preamps I've heard, and liked, I would recommend the following:

- Parasound JC2 or JC3
- Ayre KX-R

Of those I haven't heard but would check out, based on reputation and previous auditions of older equipment:

- BAT
- Pass Labs

But personally, I would still keep looking for a quiet tubed preamp.

jimbones · September 28, 2012, 08:59:35 PM

Ouch, those are like $4000

bpape · September 29, 2012, 07:06:11 AM

That was kind of what was mentioned earlier. To get something in a SS preamp that's going to compete with your AR piece, it's not going to be inexpensive.

Bryan

richidoo · September 29, 2012, 12:02:43 PM

Something to consider is autoformer volume control. It is passive, but has good impedance behavior, better than passive resistive attenuators.

Dave Slagle's Intact Audio site:
http://www.intactaudio.com/atten.html
http://www.enjoythemusic.com/diy/0611/slagle_autoformer_volume_control_modules.htm

The Bent Audio Tap-X preamp uses the Slagle autoformers inside, with full preamp functions and remote, good price.
http://www.bentaudio.com/index2.html
http://www.audiocircle.com/index.php?board=27.0

The autoformer is silent and has good impedance drive at low volume levels. I think the bent also has +6dB active element that kicks in when you crank it up. I have heard really great things about this preamp.

Pass makes the B1 buffer, and many variants of it, which is zero gain, active JFET buffer. Sounds very nice, relaxed. No feedback, class A.

The Lightspeed Attenuator is an optical resistor that supposedly is extremely low distortion volume control. I don't know anybody who is making a full function preamp using these parts yet, except for DartZeel. Sam Tellig raves about this thing all the time, but his version has no buffer circuit, just passive volume control. Low price

Placette makes some stepped resistor based volume controls which are relatively inexpensive, but also passive. They have an active version which is awesome, but $6k.

The best SS preamp I have ever heard is the SMc Audio VRE-1 preamp made by Steve McCormack. Ten large last I checked.
http://sudvarg.com/SMc/product_vre-1c.php

You'll find a couple of really cheap diy preamps on Agon right now. They look OK, selling for less than the cost of parts. Might be worth a try if you can live without a remote.

A used Parasound JC2 would be my first choice among commercial traditional full function preamps, or the Bent TapX.
Rich

BobM · September 29, 2012, 08:25:32 PM

There's some nice things on Audiogon now to consider in the $2K and under range.

Ayre K-5Xe - $2150
Pass X-1 - $2100
Pass Aleph 1 - $1000
CJ LS18 - $1950
Herron HL-1 - $1850
Levinson ML-10A - $1495
Rowland Consance - $1500

But there are also good tuned pre's available:

Audible Illusions M3B - $2195
Audible Illusions 3A - $1199
AR SP3 - $2500
There's also a bunch of CJ's, but I am not knowledgeable anough to know their different souonds, and they do all sound different, just like a lot of AR gear.