[bellhead]

I really like my Ultra+ EC preamp. It is very natural with just the right tube flavoring.
This preamp makes vocals, strings and woodwinds less "digital" and piercing on many problematic CDs
I have (versus my old solid state Jeff Rowland solid state Capri preamp), but still preserves the solid, controlled bass of
solid state preamps I used. Overall, it is very liquid with and smooth with just a touch of silky-softness that is great for digital.
It is very non-fatiguing. And still, I don't get the sense that anything critical to the music
is blunted or missing or glossed-over. If I was tuning a preamp by ear, this is how I would do it.

I was wondering if upgrading to better NOS 6CG7 tubes is a good idea (like RCA clear tops).

I notice that the stock tubes are almost right up against the top cover, with virtually no clearance.
Is there a chance new tubes would be too tall to fit?

As far as replacing tubes, I assume I just remove all the top cover screws (I count 10 of them) and that's it.
Is there anything else I need to know?

I am asking this because I upgraded the tubes in my Ray Samuels B52 headphone amp and greatly improved the sound,
making things warmer and smoother, but not removing any detail, and curing a lot of digital glare.

Also, is the AVA upgrade possible for this July 2010 Ultra+ EC?

Thanks for any response. I really appreciate it.

(One other thing I notice is that the treble control is very effective, and does not introduce any distortion or grunge like I
have come to fear with tone controls I had in the past on McIntosh and Accuphase preamps. I just use it to reduce the highs
on some CDs. It is very subtle. These may be some of the best tone controls in audio.)

[martyo]

Hi bellhead. Glad you like your Ultra. Here is the link to the original thread about the 6CG7 tubes. Reply #48 is a pic of my pre and DAC. http://www.audiocircle.com/index.php?topic=73173.40

There are also a couple of threads back at this same time about NOS 6CG7 tube rolling impressions.

As far as NOS, some guys liked the Brimar/Mazdas. They are shorter and will fit without spacers. I tried them and was using them for awhile. Two of us bought them from Upscale Audio and we both had failures after a month or so. I'd suggest a different vender.

I was working with the T8 and Ultra DAC so there were two variables. I started with the RCA clear tops. Too much ssssibilance for me, but I sold mine to another guy here and they worked for him. Then the Mazdas. I ended up with current production EH's in the T8 and NOS Amperex in the DAC. 

[tgp06]

bellhead- on each side, there are 4 screws located just above the bottom edge- the middle 2 also secure the cover. So that should be a total of 14 rather than 10. 4 on each side and 6 on top.

[tgp06]

bellhead- if your EC is recent production and came stock with 6CG7s, any 6CG7 should fit without spacers. Lots of brands available out there at reasonable prices.

[avahifi]

Most recent AVA preamps have 12 cover screws, 6 on the top, three on each side.

Leave the the bottom front corner and bottom back corner screws on each side alone.

Regards,

Frank Van Alstine

[bellhead]

Ok, thanks everyone for all the kind responses.
I was also wondering if my Ultra+ EC would be better off with the new upgrade.
(I think it can get it from the posts here in the forum.)
It was manufactured this July (serial 060710C).

[bellhead]

I got these Black Sable RCA 6CG7 Cleartops (cryotreatment claimed on the tube) and they are excellent.
They made the stock Electro-Harmonix ones sound like... transistors. They really transformed the sound, more than I expected.
They have great tube rush and the bass is much better controlled, but still warm and pleasant.
Before, I wasn't too sure I was listening to a tube or solid-state amp sometimes, but the RCAs bring a full tube sound,
and it is great. It is very resolving, so you really can hear the fine differences in the recording. It really digs deep into the
recording, and I can tell it is more truthful. If there is more or less grain in a vocal, I hear it. But the Ultra+ EC with the RCA tubes now translates
digital harshness or glare into something much more palatable, and the good things really shine through.
Like the grain that was sandpaper-like is now a natural roughness that is what I hear in a true, live vocal.
And the upper highs are sweeter.
Digital glare is also reduced considerably, and I rarely wince at this anymore, even in my old 1980s discs.
And like I said, the Ultra's treble control is the best tone control I ever heard, with no "strangeness" when activated,
and has a subtle but just-right affect. (If Frank could get this tone control on his AVAstar, I would really consider it.)

As far as removing the cover, Frank (of course) was right about the 12 screws. (And you need to know exactly the right ones.)
You need to be careful because the screws are very small and you need to be gentle so as not to strip the delicate Philips head.
(I wish a sturdier screw was used.) Otherwise, it was pretty easy.

[martyo]

I got these Black Sable RCA 6CG7 Cleartops (cryotreatment claimed on the tube) and they are excellent.
They made the stock Electro-Harmonix ones sound like... transistors. They really transformed the sound, more than I expected.
They have great tube rush and the bass is much better controlled, but still warm and pleasant.
Before, I wasn't too sure I was listening to a tube or solid-state amp sometimes, but the RCAs bring a full tube sound,
and it is great. It is very resolving, so you really can hear the fine differences in the recording. It really digs deep into the
recording, and I can tell it is more truthful. If there is more or less grain in a vocal, I hear it. But the Ultra+ EC with the RCA tubes now translates
digital harshness or glare into something much more palatable, and the good things really shine through.
Like the grain that was sandpaper-like is now a natural roughness that is what I hear in a true, live vocal.
And the upper highs are sweeter.
Digital glare is also reduced considerably, and I rarely wince at this anymore, even in my old 1980s discs.
And like I said, the Ultra's treble control is the best tone control I ever heard, with no "strangeness" when activated,
and has a subtle but just-right affect. (If Frank could get this tone control on his AVAstar, I would really consider it.)

As far as removing the cover, Frank (of course) was right about the 12 screws. (And you need to know exactly the right ones.)
You need to be careful because the screws are very small and you need to be gentle so as not to strip the delicate Philips head.
(I wish a sturdier screw was used.) Otherwise, it was pretty easy.

Cool you found a winner for you.
I just leave the screws out.

[s4cabriolet]

It is dangerous to criticize screws in this forum - I was excoriated on my rusty screws remark 

[JerryM]

It is dangerous to criticize screws in this forum - I was excoriated on my rusty screws remark 

   That's why you leave the screws out! 

(I do, too, Martyo!)

To stay way more on-Topic: Roll those tubes!!! There is no point in wondering...   

Have fun,
Jerry

[martyo]

It is dangerous to criticize screws in this forum - I was excoriated on my rusty screws remark 

If the amp had the case and face plate screws replaced with SS then it was my amp, the original ad with reference to the rusty screws was attempt to be accurate and inject some humor - I sorely regret it.  BTW I have been a loyal customer of Frank's for years and did not intend disrespect.  I will never live this down!

Gee, I had almost forgotten about this.  If you keep reminding us.........

[Brett Buck]

As far as removing the cover, Frank (of course) was right about the 12 screws. (And you need to know exactly the right ones.)
You need to be careful because the screws are very small and you need to be gentle so as not to strip the delicate Philips head.
(I wish a sturdier screw was used.) Otherwise, it was pretty easy.

   You don't need a sturdier screw, you need a different screwdriver. I have found these to be excellent:

    http://www.trossenrobotics.com/store/p/5073-Genuine-Japanese-Industrial-Standard-Screwdriver-Set.aspx?feed=Froogle

    (just the first link I found, they are around for cheaper than this)

    They are supposedly JIS (Japanese Industrial standards) Cross-head drivers, but they work exceptionally well for conventional Phillips head screws as well. At least as secure from slipping or camming out as Allen head screws. Get the right size and you can stick it in the screw head and let go, with it horizontal, and it won't fall out.

    Brett