[Wind Chaser]

No magic, no good sounding or bad sounding rectifier tubes, just one with the right output voltage for your circuit needs.

I think Steve Deckert also once said something along this line.

[rlee8394]

More of what Frank recommends:

"Van Alstine version:
For your information, we recently posted a small upgrade to our Ultimate 70, Ultravalve, and even stock Dyna St-70 amplifiers. All that is necessary is to install two 1N4007 diodes, one in series with each high voltage power transformer lead to the 5AR4 rectifier tube. The diodes will mount on unused 5AR4 socket pins. The purpose is to prolong the life of the rectifier by reducing the impact of cold hard turn-on AC voltage to the tube.We recommend this for any vacuum tube amp using a 5AR4 rectifier tube."

This will also increase PIV from 1700 volts to 2700 volts for greater performance/safety.

Ron

[sfox7076]

It's tuning via voltage drop.  I prefer 5R4GYs in my DAC circuit. 

[FullRangeMan]

Dear Frank:
Sorry the out of topic but you had any recommendation for SS diode bridge? (Vishay GP10Y-E3/54)
http://www.digikey.com/product-detail/en/GP10Y-E3%2F54/GP10Y-E3%2F54GICT-ND/3026056

[Yomaha]

I'm still pretty new to the tube amp world, so excuse me if I sound like an uniformed noob (bc I kinda am), but Andy was saying that in part, do the actual shape of the tubesa 274B or other tall tube tended to impact the airiness and the stereo spectrum to an extent.  This is compared to a shorter tubelike the Mullard that would have a more focused sound.  I don't remember the specific details of the distance between the internal parts that he mentioned, but I found that interesting.  I did like the openness of the 274B, which according to Andy will not be as pronounced in the Mullards because of design specs, but it was a compromise I am making.  Do those comments about tube design, short bottle versus tall bottle affecting openness of sound stage, sound familiar to any users?

[FullRangeMan]

I'm still pretty new to the tube amp world, so excuse me if I sound like an uniformed noob (bc I kinda am), but Andy was saying that in part, do the actual shape of the tubesa 274B or other tall tube tended to impact the airiness and the stereo spectrum to an extent.  This is compared to a shorter tubelike the Mullard that would have a more focused sound.  I don't remember the specific details of the distance between the internal parts that he mentioned, but I found that interesting.  I did like the openness of the 274B, which according to Andy will not be as pronounced in the Mullards because of design specs, but it was a compromise I am making.  Do those comments about tube design, short bottle versus tall bottle affecting openness of sound stage, sound familiar to any users?

Iam more uninformed than you, so in my ignorance I could say not, its not the bottle, big bottles only has more air molecules inside than a small bottle and a thick glass just decrease microphony.
But lets wait Frank opinion

[Yomaha]

I got the fat base Mullard gz34 into my amp last night.  First impressions are that it is sonically superior to the Tube Amp Doctor gz34 I replaced.  As noted in several other online reviews elsewhere, the mids were/are fantastic.  Lots of detail, lush and not harsh or brittle. Was able to hear subtleties of pick sounds, string sounds, and other nuances that I had not heard before in recordings I'd listened too many a time previously.   

The width of the stereo image is nice, with good instrument separation, but a bit more focused top to bottom without as much air on the top as the Princess 274b.  The bass is tight and responsive, but not as big as with the princess 274b.  I personally preferred the Princess's bass profile as it was big, nice and round, but not bloated or boomy.  I could however see it maybe being a bit much for some. 

All in all, I'm very happy with my purchase.  The tube was delivered as described by Andy, and I thought the price was very reasonable considering other prices I  had seen on the internets.  I'd be curious to try some of the big bottle RCA's that Andy has to see if it would open up space on the top end of the image.  The Mullard definitely made my system exciting and engaging again, which is exactly what I was looking for.

Now about that input tube.....