[john57]

I brought a few 3DG4 tubes with different getters, I have seen one,two and even three getters on 3DG4 tubes. My favorite 3DG4 tube is a GE with two halos getters on top not the usual two side getters. Here is what may be the 3DG4 three getter version as an example.
 
http://www.ebay.com/itm/Vintage-ZENITH-Electronic-Tube-3DG4-/260678159962?pt=Vintage_Electronics_R2&hash=item3cb1a10e5a

 

[Silent One]

The crème of 3DG4 rectifiers - now, which manufacturers would those be?

 

[Xcalibur255]

Quote:

No issues with Bass control to report. What I can report is the ITT (Japan) 6SN7GTB's sounded better in the Woo, as opposed to doing work in the OTL amp in single mode. The TS-BGRP sounds so much better... even the Ray's. 
 
I currently have a pair of recabled Senn HD600's in-house. They sound good. Though, I have preferred the sound of the Denon's to date. This leads me to believe that the OTL pairing with a low impedance phone like Denon performs better than expected. Three weeks back, I went round-n-round with the HD600-K702-D7000. Eight hours later, I still preferred the D7000. I know that's not really enough time, but I did extended runs from the 30 to 60 minutes at a time. After my brain seasoned, reasoned and settled after each switch, my order of preference did not change from the first round.
 
Additionally, though the D7000 is performing better inside the listening room than on paper, lowering the output impedance will make for a better dance partner - my D7000's can't wait! 

 More current, more happiness...
 
I'd like to hear 600 ohm Beyers and may have the chance when I visit Clayton SF in about 10 days. No need to drag the OTL amp to his apartment... he's got one! Also, as I approached 126 hours (estimated) last night on the amp, I'm hearing my first subtle hints of mellowing. 
 

I think this amp handles low impedance much better than the typical OTL design.  It gives me the impression that I don't really have to care about matching phones to the amp, though I have found that the cheaper low impedance high sensitivity cans are a bit of a no no because of how much audible hum is present.  My current setup is close enough to silent to call silent most of the time, when the tung sol BGRP isn't mis-behaving itself anyway.
 
Try the Hitachi (ITT) with those Sylvania 6AS7Gs.  You might be surprised.  It'll be a bit softer sound than the 5998s but it's very nice.  I didn't care for the Hitachi with the 5998s, it just sounded wrong somehow.  I was even more disappointed with the National Union blackglass, those were downright bad with the 5998 and uninspiring paired with 6AS7s too.  I vastly prefer them on the Woo driven by my Mullard GZ33.  I think my most pleasant surprise was the Hytron which completely gives the BGRP Tung Sol a run for its money in midrange resolution and sounds great in general.  Great tube.  I finally found love for the Brimars too, they sound sweet and seductive with great texture and depth with the 5998.  Never cared for the Brimars in the Woo.
 

 

[Xcalibur255]

Quote:

The crème of 3DG4 rectifiers - now, which manufacturers would those be?

There are only 3:  GE RCA and Sylvania.  Anything else is a re-brand.  I've never heard an RCA, and of the other two I personally prefer the Sylvanias.  The GEs sound a little flatter and duller, the tone is a bit bleached sounding to me.  Somebody else might call them more neutral, but I found it killed the musicality a bit.  My Raytheon branded Sylvania 3DG4 has been in my amp 100% of the time since I quit piddling around with my 5V3s.
 

 

[Silent One]

Quote:

There are only 3:  GE RCA and Sylvania.  Anything else is a re-brand.  I've never heard an RCA, and of the other two I personally prefer the Sylvanias.  The GEs sound a little flatter and duller, the tone is a bit bleached sounding to me.  Somebody else might call them more neutral, but I found it killed the musicality a bit.  My Raytheon branded Sylvania 3DG4 has been in my amp 100% of the time since I quit piddling around with my 5V3s.
 

The GE is what shipped; have installed now. Since prices are Earthbound, I'll look for Sylvania's later tonight! I'm looking forward to hearing the Mighty 596 once the OTL is modded and draw some comparisons (mid-April). 
 

 

[Silent One]

Quote:

I think this amp handles low impedance much better than the typical OTL design.  It gives me the impression that I don't really have to care about matching phones to the amp, though I have found that the cheaper low impedance high sensitivity cans are a bit of a no no because of how much audible hum is present.  My current setup is close enough to silent to call silent most of the time, when the tung sol BGRP isn't mis-behaving itself anyway.
 
Try the Hitachi (ITT) with those Sylvania 6AS7Gs.  You might be surprised.  It'll be a bit softer sound than the 5998s but it's very nice.  I didn't care for the Hitachi with the 5998s, it just sounded wrong somehow.  I was even more disappointed with the National Union blackglass, those were downright bad with the 5998 and uninspiring paired with 6AS7s too.  I vastly prefer them on the Woo driven by my Mullard GZ33.  I think my most pleasant surprise was the Hytron which completely gives the BGRP Tung Sol a run for its money in midrange resolution and sounds great in general.  Great tube.  I finally found love for the Brimars too, they sound sweet and seductive with great texture and depth with the 5998.  Never cared for the Brimars in the Woo.
 

I think you're right about this particular OTL build. Before receiving the amp, I'd gotten so many OTL/Low impedance, high sensitivity advisories, you'd have thought I was living in Kansas without a basement. 

 It's always great avoiding disaster inside the listening room...
 
Now curious, I think I will roll a tube or two late nite and find out more about the ITT/Sylvania combo. Thanks, it's one I have not tried - definitely more combos than I dealt with prior.
 

 

[john57]

GE made several 3DG4 getter versions of the same tube for what ever reason. Many are Sylvania. Zenith TV's in the early 1960's were a heavy user of the 3DG4 tubes it is  a very rugged tube rarely fails. 240 ma per plate for a total of 480 ma output. The 3DG4 was used in the very first Zenith color TV. The 3DG4 at 3.3 volts x 3.8 amps is is using 12.54 watts, and the common 5U4 for example, at 5 volts and 3 amps uses 15 watts of filament power. The only other rectifier tube that I ever had any luck in my amp is the 5V3A which uses 3 amps instead of the 3.8amps of the 5V3.a harder tube to find since many are mislabeled.

 

[Silent One]

Quote:

I brought a few 3DG4 tubes with different getters, I have seen one,two and even three getters on 3DG4 tubes. My favorite 3DG4 tube is a GE with two halos getters on top not the usual two side getters. Here is what may be the 3DG4 three getter version as an example.
 
http://www.ebay.com/itm/Vintage-ZENITH-Electronic-Tube-3DG4-/260678159962?pt=Vintage_Electronics_R2&hash=item3cb1a10e5a

Yeah, I got the side-getter action on the GE. Curiously, does the placement of getters on the top; extra getter, impart a slightly different sound in the amp?

 

[john57]

getter placement is talked about a great deal in 6SN7 tubes. Chrome tops, clear tops, bottom getters side getters make more of a difference for a driver tube than the rectifier tube. The GE top twin halos are a bit taller tube than the side getter which is the more common version. 3DG4 tubes are cheap enough to experiment a bit if you like without having to be concern with tube disasters.

 

[Xcalibur255]

I think getter placement is used more for identification than anything, it can't affect how a tube sounds.  If we assume the voltage drop and sag is the same for any 3DG4 made by a particular company then they *should* all sound the same.  Should. 

 

[Xcalibur255]

I kept some listening notes from my driver tube rolling that I can share, but they are super long-winded and somewhat haphazard which is why they didn't find their way onto the forum.  I really need to re-read them actually as they may not be completely valid anymore given the amp has continued to settle in since then.  At the time I was still voicing complaints about sibilance, something that has since banished itself to near non-existence even with problematic material.

 

[rosgr63]

When it comes to 6SN7's used as drivers in some amps different batches of the same tube can sound different.
A different getter type probably means a different batch, assembly maybe different materials, etc.
I think that it does affect the sound but I can't say how much.
This is my opinion and experience, I don't have any technical evidence/explanation to substantiate it.
When I was talking to an ex Mullard Engineer about the subject regarding ECC32 getter types, he laughed.
He thought there was no difference in sound but some people had a different opinion.

 

[john57]

The key word is should. I always wonder why would GE even bother to make different getter versions of the 3DG4 tube and make one larger for what for? The 3 getter version might have a better vacuum with less AC leakage perhaps. There might be a difference in the plates capacitances that might interact with the rest of the circuit. The trouble with tube manuals is that they never quite quote exactly same figures for Voltage drop, sag and current on the same tube expecially with the 5V3 tubes the numbers were all over the place. I wish I had a tube test socket so that I can measure the voltage potentials and the noise levels with a scope on my setup. But in the end it is how the ear and you hears is what matters and you even have a perference for the Sylvania. On paper and the math is seems that it should not matter sometimes.

 

[Silent One]

 
FYI @ Xcalibur255
 
I too, may end up with a 45 amp... and soon! This Blue Power light is way too bright for my late night/overnight sessions. I like silence and darkness in the background. I'm close to re-positioning the amp at a 45 degree angle. 

 
Didn't mean to imply I was getting a 45 amp.

 

[Xcalibur255]

Quote:

When it comes to 6SN7's used as drivers in some amps different batches of the same tube can sound different.
A different getter type probably means a different batch, assembly maybe different materials, etc.
I think that it does affect the sound but I can't say how much.
This is my opinion and experience, I don't have any technical evidence/explanation to substantiate it.
When I was talking to an ex Mullard Engineer about the subject regarding ECC32 getter types, he laughed.
He thought there was no difference in sound but some people had a different opinion.

For drivers and power tubes I can agree with this actually.  My statement was meant more for the 3DG4 and rectifiers in general since producing the B+ is their only contribution to the audio signal so long as the voltage drop and sag is consistent from tube to tube within a specific type and brand they should also sound consistent was my thought.