Little Dot Tube Amps: Vacuum Tube Rolling Guide
Jan 22, 2014 at 9:49 PM Post #4,757 of 13,432
Sylvania 6SN7GT "Bad Boy"
 

 
Manufactured in the early 1950s, tall bottles, 3-hole T-plates, and bottom getter. Relabeled tubes do exist and can often be purchased for less.
 
Much has been written about the sound of this tube, so I will not go into much detail. The bass is a bit more forceful and present than the Tung Sol BG/RP, the mids are somewhat warm and sweet, and the highs are crystal clear and airy. I like this tube a lot. However, compared to the TS, it comes up a bit short in the sense of 3-D space and imaging that make the TS so involving and addictive.
 
Comparing the Sylvania to the Heerlen-made Amperex E188CC, the bass is stronger, the mids are not as lush, but still sweetly warm, and the highs are a bit more airy. Both tubes have excellent detail and transparency. The Sylvania's 3-D stage is slightly deeper, but not much, and in my system, it is quieter. In my mind, the Amperex and the Sylvania are very similar and neither is significantly better than the other. And I still prefer the Tung Sol over both, due to its superior 3-D stage and imaging.
 
Jan 22, 2014 at 11:06 PM Post #4,758 of 13,432
Hey guys, looking to start tube rolling and wanted to check these were ok for a mkII and to get some opinions before I order anything. Thanks. 
 
http://www.ebay.co.uk/itm/310282214423?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649
 
 
http://www.ebay.co.uk/itm/6N6P-i-STONG-MATCHED-PAIR-tubes-NOVOSIBIRSK-Gold-grid-NOS-for-Little-Dot-MKIII-/141172381174?pt=Vintage_Electronics_R2&hash=item20de8795f6
 
Jan 23, 2014 at 12:00 AM Post #4,759 of 13,432
   
Do you know? Does the Brimar 13D1 sound significantly different than a Brimar 6SN7?

 
 
The 6SN7 equivalent is the 13D2, which sounds different from the 6SN7 Brimar.
There is a variety of Brimar 6SN7 so I need to see a photo to be sure we're talking about the same tube.
 
They came with black or brown base, clear or smoked glass, with or with out top coolers, O-ring getters, square getters and so on. 
 
The GTY version is a nice tube too.
 
Jan 23, 2014 at 2:17 PM Post #4,760 of 13,432
Hi chiman,
 
Instead of the 6N6P-i, spend a little extra money on a pair of 6N6P-IR tubes. Then, instead of the Mullard tubes, order a pair of the 6HM5 Yugoslavian Ei tubes for $10 best offer.
 
The total price should be the about the same or less, but the results will be better.
 
 
  1. $T2eC16J,%21%29kE9s4Z-532BRN3+Cb4Nw%7E%7E60_14.JPG

6HM5 /6HA5 / EC900 export quality audio triode tube / NOS / FREE SHIPPING /

 
http://www.ebay.com/itm/6N6P-IR-ECC99-E182CC-PAIR-High-Durable-Double-Triode-Gold-Grid-NOS-OTK-/181267476422?pt=Vintage_Electronics_R2&hash=item2a34622fc6
 
Good luck!
 
Jan 24, 2014 at 12:00 AM Post #4,761 of 13,432
Hi rosgr63,
 
Shopping around for 12SN7 tubes I came across two other tubes that are supposed to be higher grade than the 12SN7 tubes for use in aircraft servo systems.
 
They are labeled 12SX7 and 2C52 and both are octal tubes. Would you know anything about them? Are they compatible with the 12SN7/6SN7 wiring, and is there any advantage using these tubes?
 
Jan 24, 2014 at 12:55 AM Post #4,762 of 13,432
They appear to be compatible, but I have never tried the 12SX7.
 
Jan 24, 2014 at 9:52 AM Post #4,763 of 13,432
  Hi rosgr63,
 
Shopping around for 12SN7 tubes I came across two other tubes that are supposed to be higher grade than the 12SN7 tubes for use in aircraft servo systems.
 
They are labeled 12SX7 and 2C52 and both are octal tubes. Would you know anything about them? Are they compatible with the 12SN7/6SN7 wiring, and is there any advantage using these tubes?

 
The 12SX7 is electrically identical to the 12SN7. The only difference is that it was designed to be less microphonic. So yes, it is simply a premium version of the 12SN7.
 
The 2C52 is a high mu dual triode. While the 12SN7 has a mu of about 20, similar to a 12AU7, the 2C52 has a mu of about 100, similar to a 12AX7. This tube should work fine in our LDs as we have successfully used the high mu 12AX7 before and the pin-out is the same as the 12SN7.
 
Jan 24, 2014 at 12:54 PM Post #4,764 of 13,432
I have no experience of the 2c52 but the 12sx7gt is a great valve. It will consistently outperform all the 6 / 12sn7gt I use (basically all of them). It has lower distortion and is one of the cleanest sounding valves I know. Originally designed by GE I think, I have only ever found KenRad and RCA examples. It was used in 26v string radios and not audio. It's use was largely over by 1955. My last examples are from 1955. RCA are by far the most common, though I have never got the bottom of the Canadian examples. Interestingly these Tubes were heavily burned in before release so often have spotty getter which many people think are heavily used examples when in reality are NOS! This does allow more negotiation on price if the seller doesn't know what they have :) you do need to give them a nice DC heater voltage however and this puts many off using this tube. Certainly a tube to try further if you have a separate PSU.
 
Jan 24, 2014 at 1:58 PM Post #4,765 of 13,432
  Hi chiman,
 
Instead of the 6N6P-i, spend a little extra money on a pair of 6N6P-IR tubes. Then, instead of the Mullard tubes, order a pair of the 6HM5 Yugoslavian Ei tubes for $10 best offer.
 
The total price should be the about the same or less, but the results will be better.
 
 
  1. $T2eC16J,%21%29kE9s4Z-532BRN3+Cb4Nw%7E%7E60_14.JPG

6HM5 /6HA5 / EC900 export quality audio triode tube / NOS / FREE SHIPPING /

 
http://www.ebay.com/itm/6N6P-IR-ECC99-E182CC-PAIR-High-Durable-Double-Triode-Gold-Grid-NOS-OTK-/181267476422?pt=Vintage_Electronics_R2&hash=item2a34622fc6
 
Good luck!

 
how would you compare these to the 6av6 variants?
 
Jan 24, 2014 at 3:01 PM Post #4,766 of 13,432
Hi mab1376,
 
From reading chiman's post I got the impression that he was just starting to do tube rolling, and that the tubes he picked required no modifications at all. I can well understand the hesitation and worry about using straps and adapters, so that's why I suggested something simple that is plug and play.
The 6AV6 tube is very good, but it requires switching to EF92 setting and  cutting off and taping pins 5&6, and not everybody is comfortable in doing this.
 
As you well know, there are many driver tubes that are significantly better, but these tubes require modifications or adapters and voltage regulators.
 
I could see a market for an adapter package with a built in voltage regulator and different switches for using 6DJ8 wiring and 12AX7 wiring, as well as octal and loctal adapters (and a C3g adapter!).
 
Jan 24, 2014 at 4:06 PM Post #4,767 of 13,432
  Hi mab1376,
 
From reading chiman's post I got the impression that he was just starting to do tube rolling, and that the tubes he picked required no modifications at all. I can well understand the hesitation and worry about using straps and adapters, so that's why I suggested something simple that is plug and play.
The 6AV6 tube is very good, but it requires switching to EF92 setting and  cutting off and taping pins 5&6, and not everybody is comfortable in doing this.
 
As you well know, there are many driver tubes that are significantly better, but these tubes require modifications or adapters and voltage regulators.
 
I could see a market for an adapter package with a built in voltage regulator and different switches for using 6DJ8 wiring and 12AX7 wiring, as well as octal and loctal adapters (and a C3g adapter!).

 
I would gladly pay for a c3g adapter if someone wanted to start selling them based on Hypnos1's feedback on those tubes
beyersmile.png

 
I've also really wanted to try 6SL7 tubes for quite a while but just don't have the time to start building adapters. I'm just bad with making my own adapters due to lack of time and lack soldering/assembly skill.
 
I've been using 6AV6 tubes for about 6 months and just a little antsy to try some tubes i haven't personally tried.
 
As we know rolling is an addiction! :)
 
Thanks for the feedback!
 
Jan 24, 2014 at 4:52 PM Post #4,770 of 13,432
Hi Gary,
 
Have you heard the Tesla's Yet?
I have been using Mullard 8100's and Voshkod 6ZH1P-EV and I find the 1953 Tesla's I now have burned in have a smoother top end. A more subterranean bottom with faster transients, better (but not wider! Maybe more height information) and a more liquid sound. I am using 6H30-PI as power tubes.
My background is Many years of high end Audio, but not so much headphones. Just getting into it heavy now I am in a Condo.
Hope this helps. 
 
Steve.
 

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