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12ax7 for ARC SP16

Posted on October 3, 2011 at 23:34:10

Posts: 119
Location: USA
Joined: September 30, 2007
Just wondering if there are some Audio Research SP16 owners out there who have tube rolled on this preamp. I just got this couple days ago locally from a gentleman(I have their VS110 as amp), so far it sounds very good with just factory tubes (it's I think 4-5 yrs old), but I'm sure there are tubes out there that would be better suit with this pre.

Also, I don't know why, but the pre stage is using 3 12ax7, do I need to change all 3?

And what about using other 12au7/12at7 tube instead, the gain to me currently is actually abit too much with my mhdt Havana.

Thanks and good listening!


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RE: 12ax7 for ARC SP16, posted on October 4, 2011 at 07:08:52
Bored Member

Posts: 12800
Joined: July 31, 2007
May 17, 2009
Maybe, just let the system break-in, before rolling tubes. Surprisingly, rolling various 12A(_)7's in the gain stages sometimes doesn't really change the gain all that much. Maybe, the overdrive, esp in guitar amps. And perhaps the headroom. But not the overall loudness--- as that is often set by parameters (voltage, bias) around the tube and not just the tube itself.

If you are dead set on rolling, the input stage usually has the most effect on the gain and overall tone. Tubes connected to the RCA inputs.


RE: 12ax7 for ARC SP16, posted on October 4, 2011 at 08:59:59
JJ Triode

Posts: 715
Location: Northwest
Joined: December 2, 2004
This classic circuit uses a lot of feedback, so changing to, say, 12at7 or even 12au7 will not change the gain as much as you may expect. The plate resistances of these tubes are also much less than the 12ax7, throwing off the operating point considerably. I recommend staying with 12ax7 types. The Gold Lion reissues have gotten some good comments, as have several others.


RE: 12ax7 for ARC SP16, posted on October 4, 2011 at 11:15:40

Posts: 492
Location: Maryland
Joined: March 28, 2004
The three tubes, from what I remember are Left, Right, (V1 & V2) and Cathode Follower (V3)

I have used NOS, but since there are some pretty decent new production tubes out there (IMO), I have quit chasing the NOS train. Your tastes may vary, so try both NOS and new.

For new production, I like the Psvane 12ax7, and the new Gold Lion 12ax7. I found the GL to be more laid back sounding than the Psvane, so you may need to try both to see which you like better. I had liked the TS Full Music 12ax7, but the Psvane and GL are better for my tastes and my rig.

IMO you also get nice improvements with Power Conditioning and Power Cords on this Pre - but again that is something you need to decide on getting into or not.


RE: 12ax7 for ARC SP16, posted on October 5, 2011 at 04:39:56

Posts: 81
Location: Atlanta
Joined: June 15, 2010
I would suggest that you go with the Genalex 12AX7. We've had nothing but positive reviews and feed back on them.
A studio is a financial black hole with good acoustics.

It is only vintage if it works. Other wise it is just old crap.


RE: 12ax7 for ARC SP16, posted on October 6, 2011 at 06:30:27

Posts: 1585
Location: East Coast
Joined: May 23, 2004
My experience with rolling tubes in an ARC pre proved to me that I could do almost nothing to change the "gain from hell" using various 12--7 tubes. Indeed the first position in the three tube chain had the most noticable imoact on tone the other ttube seemed to have akmost no real impact. I happened to like the original OEM old stock tubes which were made for ARC by BEL of India. I also found that using 12AU7s did something which seemed to result in an awful lot of woofer travel and didn't sound any better but scared me.
5751s are usually my favorite 12AX7 type and worked out OK but the real "High Definition " signature ARC sonic was best heard using 12AX7s. I stopped using it in favor of a 6SN7 pre and left more than decent sounding Shuaguang 12AX7C9s and regular new production Tung Sol 12AX7s in it.


RE: 12ax7 for ARC SP16, posted on October 8, 2011 at 07:01:54

Posts: 739
Location: New England
Joined: June 14, 2008
Recently found a 12AX7 that one would not think would be all that special, BUT, in fact, it's one of the best performers I've herad.

Found a stash of Japan 12AX7 (14 mm) plates that are marked Raytheon Military with a 64 date code. These are amanzing, very low microphonics, very low noise, balanced sections, and one of the most neutural tonal balances I've ever herad. They look like a Mullard clone, but they could also be a Raytheon clone, as I've one pair from 63 marked Raytheon USA that perform the same.

Also found a stash of Japan 12AU7's that are either marked Daystrom or Baldwin. They are 17 mm plates, and look to be a Mullard clone. Same type of perfromance, low noise, microphonics, matched sections, etc. These are also great perfromers.

The Japanese tubes from the 60's seem to be as good as the US/Euro tubes they copy. Thanks to what appears to be high quality control, there is a high probability they will perform well.

Lastly, noticed the Japan tubes from the 60's flashing looks like the US/Euro tubes, in that they silver vs. carmel colored.
"What this country needs is a good 5 watt amplifier!" (Paul Klipsch)


RE: 12ax7 for ARC SP16, posted on October 8, 2011 at 21:07:06

Posts: 119
Location: USA
Joined: September 30, 2007
Thank you guys! I ordered the gold lion, gonna try it with the SP16. Overall I'm very satisfy with this preamp. Gain is abit more, but damn it sounds neutral with a touch on the warm side, very nice.

The reason I didn't wait for the VS115 and just went with the VS110 was also because of the JFET. Frankly all tube is fine with me, no need with neutral JFET in those new ARC. I think I can live with this system for a very..very..long time.

My spk is Legacy Classic HD. full range with 94db. No complaint...nowaday I just sit back and relax, no swapping cables even.


RE: 12ax7 for ARC SP16, posted on October 24, 2011 at 18:13:27

Posts: 169
Location: ny
Joined: August 3, 2003
I also have the SP16 and the VS110 and have experienced many tubes and finally settled on the Amperex 12AX7 long plate tubes. The telefunkens also sound good too. Obviously it all depends on your other gear as well. I'm also using a tube CD player and highly enjoy the sound from my system. Also, heard that changing the power tubes on your VS110 to the KT-120's will yield more bass and throw a wider soundstage and better midrange. Confirmed with Audio Research that this works with the unit.


RE: 12ax7 for ARC SP16, posted on October 24, 2011 at 22:19:10

Posts: 119
Location: USA
Joined: September 30, 2007
Thanks. I'm also waiting on the current set of kt88 to get used up. Frankly I really dunno how long they last. But a full set of kt120 is mighty tempting.


RE: 12ax7 for ARC SP16, posted on October 25, 2011 at 05:01:48

Posts: 169
Location: ny
Joined: August 3, 2003
no problem. Had mine replaced after about 8 years or so after one of the tubes arced and took out a couple of resistors. But they should last 2000 to 3000 hours or so. Make sure you bias the VS110 to 65mv. Tempting to get the KT-120 as well for $400 or so for practically a new amp.


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