Tube Pre Amp for McCormack DNA 0.5 - Covergent MKII?

Any tube preamp will work- the input impedance is 100K nt, posted on October 21, 2014 at 08:27:30
Ralph Manufacturer Posts: 4769 Location: Minnesota Joined: April 24, 2002	-

RE: Tube Pre Amp for McCormack DNA 0.5 - (agree, ANY), posted on October 21, 2014 at 14:20:15

Rick58
Audiophile

Posts: 1118
Location: No. California
Joined: January 24, 2001

of course there are many factors that go into a decision, but I think it's pretty safe to say that ANY tube or SS preamp will be a good match electrically etc. with the amp.

If it sounds like the DNA-1 reviewed by Stereophile and others, seems like a very good amp, smooth, detailed, etc..

I would say look at features that are appealing to you in your price range and just pick the one that you like the best! There's lots of info/opinions on how certain preamps sound (some may be 'golden/burnished/tubey' while others may be 'crisp/detailed/modern' and everything in between.

Sorry, this isn't really a recommendation! but what do you need in a tube preamp? phono or linestage only? remote control? tone controls? remote control of volume, bass, treble, balance, mono, trim level between input sources, etc. etc. ? or no remote at all?

I think those things can answer your question, without concerns of 'matching' electrically or tonally with the McCormack amp. It just seems like a fairly 'neutral' good sounding amp with high input impedance, which makes it easy to match with.

If you like the CAT SL-1 Mk II pre (see link) which I assume is what you're talking about, go for it !!!

http://www.stereophile.com/content/convergent-audio-technolo

RE: Tube Pre Amp for McCormack DNA 0.5 - (agree, ANY), posted on October 22, 2014 at 04:38:33
fantja Audiophile Posts: 15518 Location: Alabama Joined: September 11, 2010	Thanks! for sharing Rick- the CAT is on my short-list to audition as soon as I find a dealer/retailer.

RE: Tube Pre Amp for McCormack DNA 0.5 - Covergent MKII?, posted on October 22, 2014 at 09:24:54
wheezer Audiophile Posts: 4309 Joined: January 24, 2001	Steve's amps sound wonderful. I had the pleasure to work on one. Of course I couldn't resist having a listen to the 125. The DNA 0.5: Input sensitivity: 0.85V will present an issue for any mid to high gain preamp. Steve offers a step-down tranny to address this. Cheers, W

RE: McCormack DNA 0.5 gain/sensitivity, posted on October 22, 2014 at 11:55:45

Rick58
Audiophile

Posts: 1118
Location: No. California
Joined: January 24, 2001

seems that the gain (30dB) and sensitivity (0.85V for full output) are higher than 'usual', and the gain of the CAT is pretty high also (26dB or something for line) ...

So, this might mean the volume would have to be set 'lower' than with other amps, and noise MAY be an issue with high sensitivity speakers?

What preamp is the OP using now? Does the CAT sound best with the volume controls mid-point or higher? I guess there are a couple of questions, but certainly doesn't mean the CAT won't sound wonderful with the 0.5.

Of course, YMMV, etc. ...!

I'm curious as to the topology..., posted on October 22, 2014 at 15:43:01
wheezer Audiophile Posts: 4309 Joined: January 24, 2001	As the CAT MKll has ten tubes!

RE: I'm curious as to the topology..., posted on October 22, 2014 at 17:29:11
Crescent Audiophile Posts: 2 Location: IL Joined: October 21, 2014	Thank you all for your thoughts and experience. My system is Mccormack DNA 0.5 Amplifier - YamahaCX 600-U Pre Amplifier - KEF 104/2 speakers. The Mccormack just replaced a Carver TFM 15 amp and is a huge step up. With that in hand I am looking at the Pre Amp. Ray

RE: Yamaha preamp, posted on October 22, 2014 at 18:11:20

Rick58
Audiophile

Posts: 1118
Location: No. California
Joined: January 24, 2001

Hey, I have the Yamaha A-700 integrated amp (ca. 1981), still in use in my garage. I like the Yamaha 'loudness' contour method, certainly the correct way to do this. It sounded good as my main amp for several years, but when I went to tubes (Dynaco SCA-35 integrated amp, ca. 1965) around 1995, I heard a lot that I was missing (space, depth, sense that real musicians were playing together ...).

Another 'funny' coincidence, I knew a guy that had the KEF 104/2 speakers, and the (then new) Carver Receiver. He loved the combo (it did sound good to me as well), I think he may still have that setup.

I am totally guessing, but think certainly the CAT preamp is 'worth a try' with the DNA 0.5, and if you find you can't turn the volume up hardly at all from 'off' without it getting too loud, maybe look into the transformers that someone mentioned above. I am guessing that these would be some 'plug' looking things that would be inserted inline with the interconnects between the outputs of the preamp and the inputs of the amp. It's just a way to reduce the voltage coming out of the preamp by 2x or so. There certainly isn't any concern about 'hurting' anything. Just when you turn things on for the first time, don't have the volume turned way up! Start at 'zero' or very low and increase slowly.

It should be 'OMG' better sounding than the Yamaha ... and should be for several times the price!

I have read about the need to rebuild/replace the internal woofers in the 104/2s though ... if these have the original woofers, you may want to look into that. Certainly a classic excellent sounding pair of speakers.

AI Mod 3A was great, posted on October 22, 2014 at 19:16:01
jefe Audiophile Posts: 1869 Location: rocky montains Joined: December 29, 2000	Years and years ago I had the .5 Delux and Mod 3A and it was great. Divorce led to the sale which I still lament.

I've had a DNA-1 Deluxe for decades., posted on October 22, 2014 at 20:49:33

Rick W

Tubed pre's and the DNA-1 are really a good match. I've always used a CJ pv10 with the McCormack and have been pretty happy with the sound. But the combination sure ain't ideal, in part due to the preamp's excessive gain.

My old original pv10 pre had waaaay too much gain for the amp -- 31.5 for the linestage!. A tech I know installed a resistor to lower the gain to about 19. Its definitely an improvement due to being able to turn the vc up to where its more linear. But still, if I turned the vc up to 12 o'clock (for either vinyl or my cdp) where it'd be even more linear I'd blow myself outta the (fairly large and open) room.

I'm gonna replace my preamp. I'm restricting my search to pre's with gain of 15 or less, preferably no more than 10. I'd be wary if the CAT has high gain. Its something to think about with McCormack amps. I gotta think they're designed to be used with passives or low gain pre's.

RE: Tube Pre Amp for McCormack DNA 0.5 - Covergent MKII?, posted on October 22, 2014 at 23:11:24

Frihed89
Audiophile

Posts: 15703
Location: Copenhagen
Joined: March 21, 2005

People sometimes forget about gain/sensitivity issues with their system when they buy new components. The result is unwanted noise, even at low volumes, difficulties with playing dynamic music, and for tubes too much system gain can accentuate even small amounts of microphonics in preamp tubes.

An often recommended fix is attenuation by resistors, which i find squeezes the life out of music, making it flat and listless.

RE: I'm curious as to the topology..., posted on October 23, 2014 at 08:11:48
wheezer Audiophile Posts: 4309 Joined: January 24, 2001	There are some pres that have gain settings. This may be an option. Otherwise, you'll have to reduce the gain with series resistors on the RCA jacks and or shunt the volume pots. Fairly easy to implement and will provide excellent results. Is the DNA 0.5's input - cap coupled or servo?

RE: I'm curious as to the topology..., posted on October 23, 2014 at 12:02:35

Steve McCormack
Manufacturer

Posts: 102
Location: So. California
Joined: May 26, 2003

The DNA-0.5, 1, 2, and HT-1 all use the same direct-coupled input with an overall DC servo to minimize output offset. The later DNA-125, 225, and HT-5 use a cap-coupled input and eliminate the DC servo. Only the DNA-500 and 750 monoblocks are fully differential with transformer-coupled inputs. All of the DNA amps have about 30dB of voltage gain for sound quality reasons (I like the gain even higher but I felt this began to cause compatibility issues). For comparison, most amps fall in the range of 24 – 27dB gain, so it is not a big difference. Still, it is noticeable when switching from a lower-gain amp, and any residual noise from the preamp will be slightly more audible.

Best regards,

Steve McCormack, designer
SMc Audio

RE: Tube Pre Amp for McCormack DNA 0.5 - Covergent MKII?, posted on October 23, 2014 at 12:25:15
farmdoc Audiophile Posts: 190 Location: No. California Joined: December 8, 2002	Agree with the tube pre--McCormack amp. I use an Gill Audio Alana tube with a DNA-1(Gold+ modded by Steve) driving Dynaudio C1's in a second system with fav results. Punch, separation, deep soundstage, with warm, but crisp sound. No fatigue here!

Most of the 'old' tube pre's have TOO MUCH GAIN in the linestage..., posted on October 27, 2014 at 11:33:01
AnalogDog Audiophile Posts: 39 Location: SW United States Joined: March 3, 2014	Like the AI 3A. Wonderful. 31 db of GAIN in the LINE stage? Who NEEDS it? My old Quicksilver is the same way...27db. What WERE they THINKING? 12-15db of gain is plenty, for an amp like that! Read my post above about using my EarMax as a linestage...bet that's about the amount of gain it'll swing. AnalogDog Mozart and Beethoven are giants...who are standing on Haydns shoulders.

Amp/Preamp Asylum

Tube Pre Amp for McCormack DNA 0.5 - Covergent MKII?

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