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Suggestions please!! --Need to replace vintage Audio Research VT 200 Tube Power Amp

I have a nearly 25 year old ARC VT200 amp, which just arc'd out on me for the 3rd time in 18 months, and I have decided I cannot sink any more money or aggravation into this amp. I purchased it used about 7 years ago, and it had just been re-tubed, and it ran problem free for me for over 5 years. Then without warning it arc'd out, resulting in a replacement of all tubes, capacitors, etc.  10 months later, the same thing happened again.  I nearly bailed on it then, but the repair shop assured me that they could "really fix it" this time, blaming the repeat issue on the need to replace all of the tube sockets and repair some thinning wiring, and they assured me it would be "like new" and should run problem free for years to come.  It's been 9 months, and it's been running fine with relatively light use (probably 300 hours since the repair) and last night the fireworks happened again. Needless to say, I've now reached the end of the road with this amp. 
So my questions are these--as much as I loved the amp (when it was working!) a comparable new ARC tube amp (which appears to be in the $15k+ range) is out of my price range. The VT 200 is currently paired with an ARC Reference 2 preamp and a tube ARC phono stage from the same era, which are working fine, and they are driving a massive pair of ProAc Response Four speakers. I listen almost exclusively to vinyl on a VPI turntable. Does anyone have a suggestion for a new power amp for under $10K (after this experience I am reluctant to go the used route)? Also, would it be OK to pair a solid state amp with these tube components, and if so, any recommendations?  Thanks!!
karmicg
bifwynne
2,206 posts
 
What gpgr4blu says makes a lot of sense.  What he did not speak about is the difference the SE upgrade made to the stock Ref 150.  I owned the Ref 150 and had ARC do the SE upgrade.

The SE upgrade is more than just a KT-150 tube drop in.  The SE upgrade also entailed numerous part change-outs.  I did the KT-150 drop-in into my stock Ref 150 and did a lot of listening.  Later, I had the SE upgrade done.  Major and very noticeable improvements across the board.  Well worth the money.

I never heard the Ref 160 so I cannot give you any comments about how the Ref 160 stacks up against the Ref 150SE.  If gpgr4blr says that the Ref 160 is about 12 to 13 percent better than the Ref 150 with KT-150 tubes, I surmise that the Ref 150SE may be closer still to the Ref 160.  

In any case, the Ref 150SE is a terrific amp.  Definitely something to consider.  

BTW, not to throw a spanner into the gears, but at some point you might want to think about upgrading your Ref 2.  Perhaps asking ARC if they still do the MK II upgrade.  

In any case, as far as the front end is concerned, you should call ARC and ask the customer service rep for some suggestions. The late model LS preamps are pretty darn good.

BIF

karmicg OP
3 posts
 
So I wound up going with the ARC Ref 150SE, and couldn't be happier! Plenty of power, not even remotely an issue, and already an improvement in SQ way before break-in hours.  Thank you all for your "sound" advice, I would have been lost without it!
Take care and stay safe everyone.
Mike
bifwynne
2,206 posts
 
Congrats!!!  Good decision.  I wish you many years of listening pleasure.  

I have some "care and feeding" suggestions.  First, as you now know, the amp is heavy: 75 pounds as a stand-alone; 100 pounds when boxed up.  Consider ordering a bunch of bias resisters from ARC (2 different resisters per tube). They are cheap.  If in the rare case, a KT-150 arcs, you can avoid sending the amp back to ARC for a simple burned resister change-out.  Hopefully, you are close to a tech who can do the job, or if you are handy, you can do it yourself.  But always remember, … there are high voltage touch points all over the place under the hood. So be very careful when fiddling under the hood.

Second, if you don't have a multi-meter with probes, you need to buy one in order to check bias.  I check bias every couple of months.  The KT-150s will drift over time.  And don't get OCD about bias changes.  Bias voltage (65 mV DC on the set tube) will change as line voltage changes.  Don't go nuts about line voltage changes.  Line voltage will change by the hour, especially if home appliances draw heavy amps, e.g., air conditioners, and maybe the washer and dryer.

Hopefully, your amp came with a tiny plastic thiga-ma-giggy screw driver to adjust bias.  If not, I am sure you can buy one from ARC.  Again, … be careful about high voltage. 

Last point … tubes.  ARC charges a fortune for replacement matched KT-150s ($275 per tube).  Kevin Deal did a great job on my last re-tube.  Bias deltas between the set tube and the slave were within 3 or 4 mVs, which is good.  ARC may be a little tighter, but not significantly so.  Upscal Audio charges $127 per tube.  You need to buy matched pairs, preferably matched quads.

I have a question for you.  Which taps have you tried and settled on?  I have switched back and forth between the 4 and 8 ohm taps many times, but have settled on the 8 ohm taps.  FR may be a little tighter on the 4 ohm taps, but for some reason my amp/speaker combo just sounds better off the 8 ohm taps.  That said, FR will fluctuate +/- .8 db off the 8 ohm taps (an Ohm's Law thing), so in a sense, the amp is a bit of a tone control.  Ignore it.  No speaker is 100% flat.  And when you consider the room effects, ... that is another tone control.  John Atkinson measure the FR of the Ref 150 (not SE) here:  stereophile.com/content/audio-research-reference-150-power-amplifier-measurements (www deleted).

If you have any questions, feel free to send me a PM.  I love the Ref 150SE.  It has been a dependable workhorse for many years.

BIF

P.S. -- If and when you think about a preamp upgrade, you will be shocked by the ARC Ref 6.  Amazing!!!

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