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05/26/22 at 18:59:58†




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Talk to me about VR tubes... (Read 465 times)
CAJames
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Talk to me about VR tubes...
04/18/22 at 02:06:19
 
...specifically the VR tubes for the output tubes. I understand how different VR tubes affect the input, but I see little if any chatter about people trying different VR tubes with the output tubes. Is the conventional wisdom just stick with the 0A3? Has anyone tried something different and it was terrible?
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Lon
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Re: Talk to me about VR tubes...
Reply #1 - 04/18/22 at 02:31:10
 
I have SE84UfO3 Monoblocks with the Anniversary Mods and I have used all four types of VR tubes for the output tubes. My favorites, in order of most to least:

Arcturus 0B3
Sylvania 0D3W
RCA 0C3W
Mullard 0A3

I get the best balance of warmth and detail with the Arcturus and other 0B3 types.
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HR-1,ZTPRE,ZBIT,ZROCK2,SE84UFO3-25th x2, CSP3-25th.Taboo Mk IV; Rega RP3 w all GrooveTracer mods PS Audio: PST+DSD,P15,NPC,PowerBases,AC-12 pwr cbls, Reference spkr cbls;Mapleshade:Samson V3;;VooDoo:Cremona+Amati intrcncts, Iso-Pods;headphones:PM1,HD800S,ZMF Ori
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JOMAN
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Re: Talk to me about VR tubes...
Reply #2 - 04/18/22 at 04:35:27
 
My understanding is that the VR tube choice for the output tubes in the UFO25 is limited to OA3.  If you order the tube set that Decware offers with the UFO25 only OA3's are supplied for the output tubes while OA3, OC3 and OD3 are supplied for the input tube.  I recall having a conversation with Steve when I first received my UFO25 and the recommendation was to stay with the OA3 for the output tubes.

Having said that I did roll different OA3's and found that there was different results from one OA3 make to another.  I ended up with CEI rebrands of Raytheon GT style OA3 in the output position.  Actually it was Lon that put me on to these.  I also found that these could be rebranded as GE OA3.  Not the clear tops.  The Raytheon have a top getter.  Recently I came across Raytheon ST type OA3 but didn't bother to order any.

Interestingly, I rolled the input VR tubes the other day.  I did not try the OA3 but I did try two different OD3's.  One was a Sylvania OD3W and the other was a GE, made in Canada OD3.  The GE OD3 VR tube is built like the proverbial brick outhouse.  The difference in sound between the Sylvania OD3W and the GE OD3 was significant.  Currently the Raytheon OC3W continues in the input position.

The point is that there are different voicing options within the same type of VR tube so IMO it is worth trying different makes of the same type of VR tube in the output position.  Fortunately these are not expensive.
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Lon
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Re: Talk to me about VR tubes...
Reply #3 - 04/18/22 at 09:13:01
 
I've had no such instruction--stick with 0A3--from Steve and in my amps so much depends on the other tube complement as well as the gain structure going into the amps. In my current (rather atypical) complement the 0B3 is a clear winner, and I like the 0A3 the least. I agree that there are definite differences to expire within the configuration (short, tall, bottle=shaped) and brand of a particular type..
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HR-1,ZTPRE,ZBIT,ZROCK2,SE84UFO3-25th x2, CSP3-25th.Taboo Mk IV; Rega RP3 w all GrooveTracer mods PS Audio: PST+DSD,P15,NPC,PowerBases,AC-12 pwr cbls, Reference spkr cbls;Mapleshade:Samson V3;;VooDoo:Cremona+Amati intrcncts, Iso-Pods;headphones:PM1,HD800S,ZMF Ori
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JOMAN
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Re: Talk to me about VR tubes...
Reply #4 - 04/18/22 at 12:47:38
 
Hey Lon,

To clarify,  it was more of a recommendation than an instruction to stay with OA3's for the output tubes for the UFO25.  So I didn't take it to mean that one could not roll the VR output to different options.  What was implied was to use the input VR tube as the primary one to voice the UFO25.

The instructions for the UFO25 also focus on rolling the input VR tube.  But they do not state not to roll the VR outputs.  So, I guess one could if they choose to.  I've rolled so many different configurations that now it's become more of a chore than I would like it to be.

After I finish rolling the Wathen Cryotubes and compare the results with what I currently have I doubt that I'll be doing any more rolling.  Today I get the set that I ordered for the CSP3.
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Lon
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"Love without
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Philip K. Dick

Posts: 19508
Re: Talk to me about VR tubes...
Reply #5 - 04/18/22 at 14:29:07
 
Thanks for the clarification, and of course the amps aren't identical. I've rolled both input and output. In my system at least the output tubes VR tubes make a significant difference. Because the input tubes are under the chassis I decided a few years ago on a Tesla tube and have left them there. I'm getting the itch to roll those again but hate to take the amps out of the system!

I'll evaluate the cryotone 6SN7 when they arrive and hope they are as special as everyone says (but I often don't agree with everyone else's specialness!) I'll try the output tubes Steve sends to them when those are ready. I don't think I'll try the rectifiers as I don't necessarily prefer those types.
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HR-1,ZTPRE,ZBIT,ZROCK2,SE84UFO3-25th x2, CSP3-25th.Taboo Mk IV; Rega RP3 w all GrooveTracer mods PS Audio: PST+DSD,P15,NPC,PowerBases,AC-12 pwr cbls, Reference spkr cbls;Mapleshade:Samson V3;;VooDoo:Cremona+Amati intrcncts, Iso-Pods;headphones:PM1,HD800S,ZMF Ori
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JOMAN
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Re: Talk to me about VR tubes...
Reply #6 - 04/18/22 at 15:47:33
 
Yes I get it, that is the use of the word "special" or "holy grail" in various comments.  I too have tried so called "holy grail" tubes that turned out to be tubes from "hell".

With respect to Cryotubes I think that they do things that other tubes do not and what they do has a definite appeal for me, and I think for others as well but perhaps not for all.  I think of them as being very different more so than special.  

It would be terrible if all we had to have for a dessert choice is vanilla ice cream IMO.  Yet they do make it for a reason.

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jec3504
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Re: Talk to me about VR tubes...
Reply #7 - 04/18/22 at 18:02:47
 
Perfect timing for this topic. Interesting using the VR tubes to change the plate voltage. Should be fun rolling the input tubes with the different VR tubes. The rabbit hole keeps getting deeper. Would ask how sounds differ with both input and output tubes, but too many variables in that question.
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CAJames
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Re: Talk to me about VR tubes...
Reply #8 - 04/19/22 at 03:05:09
 
Appreciate your insights gents, as always.
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jec3504
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Re: Talk to me about VR tubes...
Reply #9 - 04/19/22 at 04:29:14
 
Thanks for insights for sure. Lon looking forward to your Cryotubes 6SN7  evaluation.
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JOMAN
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Re: Talk to me about VR tubes...
Reply #10 - 05/13/22 at 02:49:02
 
Thought that I would put this in here although it is related to the recent Cryotube tube rolling in my CSP3-A.

With the increase in gain that the 12AX7-WCM Long Plates added I found the sound a little overwhelming.  At first it was incredibly impressive, but after a while it was a little too much, especially the bass.  I also had to take into consideration that my Vintage 8HO speakers were now well along in the break in, although with a ways to go still.

I did two things:
1, adjusted the speaker position, wider apart by one foot, a little more toe in and a couple of inches further into the room.  
2, Of more relevance for this section is that I rolled the input VR tube in the UFO25.  It was a Raytheon 0C3W, now I have the Sylvania OD3W in that position.  

I wanted to know which made more of a difference so I rolled the Sylvania VR OD3W and the Raytheon 0C3W after I had re-positioned the speakers.  Both charges were necessary, however, I would say that rolling the VR tube made more of a difference.

The bass is still the best that I have had with the entire frequency spectrum being more coherent and resolving without being over the top.  It's gone from being initially very impressive to being even more engaging.  In that regard it is even more impressive than before.

Interesting the rather large effect that a VR tube can have.
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CAJames
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Posts: 523
Re: Talk to me about VR tubes...
Reply #11 - 05/14/22 at 18:25:32
 
Yeah, clearly the VR tubes add a level of, lets call it flexibility, to these amps that is pretty unique. After an initial surge of enthusiasm for the 300B amp I confident that sticking with my order for UFO25s is the right way to go, and the VR tubes are a big part of that.

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GroovySauce
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Re: Talk to me about VR tubes...
Reply #12 - 05/14/22 at 20:29:35
 
CAJames, The level of adjustability with the UFO25th is vast.†

The rectifiers have a very pronounced change in sound. Going from a 5u4gb to a 5ar4 changes the voltage of the amp and the sound. The VR tubes fine tune that voltage to each tube. The OA3 are big, bold and strong. OD3 is delicate, spacious and euphoric. OC3 and OB3 are varying degrees between the OA3 and OD3. Different makes also sound slightly different. Then there is the bias switch, which changes each input tube! lots and lots of options!†

The back two VR spots I tried OC3s they didnít seem happy. They had a faint buzz, maybe 120hz? They also ran really warm. OB3 seemed happy and leaned the sound out, adding a bit more space.†

Then there is the input tube which there have been many discussions about. The really cool thing is once you have gotten a handle on how the tubes change the sound, you can really fine tune the sound you want. Try an input tube that is too bold? Lower one of the VR tubes and thin it out a smidge.†
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