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Little Dot Tube Amps: Vacuum Tube Rolling Guide
Oct 8, 2014 at 6:40 PM Post #7,788 of 13,448
gibosi said:
  I don't even need an amp! With 100s' of tubes, I can sniff getter gas all day long...  :) 
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If you like to share some Getter Gas you know who to call.....
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Oct 8, 2014 at 7:13 PM Post #7,790 of 13,448
trolldragon said:
  Well I received a MOST EXCELLENT gift today, four Yugoslavians came to live here in Nova Scotia!

 
 
Running 6GU7's as power tubes in this setup and these little Yugo's sound incredible!
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OK your incredible gift of four Yugoslavian's that came to Nova Scotia. It is not clear to me if all 6GU7 come from Yugoslavia it seems eBay sells one branded as Sylvania. Are those not the good ones?
 
So are you saying between Yugoslavian inexpensive 6HM5's and 6GU7 (inexpensive or not) you can have a complete plug-and-play replacement for stock tubes in the little dot IV MK SE which will be completely plug-and-play and pretty inexpensive?
 
Oct 8, 2014 at 8:41 PM Post #7,792 of 13,448
bbmiller said:
  OK your incredible gift of four Yugoslavian's that came to Nova Scotia. It is not clear to me if all 6GU7 come from Yugoslavia it seems eBay sells one branded as Sylvania. Are those not the good ones?
 
So are you saying between Yugoslavian inexpensive 6HM5's and 6GU7 (inexpensive or not) you can have a complete plug-and-play replacement for stock tubes in the little dot IV MK SE which will be completely plug-and-play and pretty inexpensive?
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Hey bbmiller,
 
The 4 pictured tubes are all 6HM5's from Yugoslavia you need the TALL version like the ones pictured, NOT the little short ones that can also be found on eBay.
 
Get the tall 6HM5,'s from this seller, most of the users of this thread has bought them from him.
http://www.ebay.com/itm/6HM5-6HA5-EC900-export-quality-audio-triode-tube-NOS-FREE-SHIPPING-/300879467071
 
The 6GU7's are the two tubes in the back of my amplifier, where the 6H30Pi usually go. They are just your general run of the mill Colour TV Matrix tubes that can also be used for audio amplification.
 
Both of these tube pairs, the 6HM5 and 6GU7 are plug an play replacements that you could use.
 
6HM5's in the front, 6GU7's in the back.

 
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Oct 8, 2014 at 8:57 PM Post #7,793 of 13,448
bbmiller said:
  OK your incredible gift of four Yugoslavian's that came to Nova Scotia. It is not clear to me if all 6GU7 come from Yugoslavia it seems eBay sells one branded as Sylvania. Are those not the good ones?
 
So are you saying between Yugoslavian inexpensive 6HM5's and 6GU7 (inexpensive or not) you can have a complete plug-and-play replacement for stock tubes in the little dot IV MK SE which will be completely plug-and-play and pretty inexpensive?
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The 6GU7 was manufactured by RCA, Sylvania  and a number  of other American companies. I do not think these were manufactured in eastern Europe.
 
If you are interested in the 6GU7, I would also suggest the 6CG7 and 6FQ7. These tubes are essentially a 6SN7 shoehorned into a 9-pin glass bottle. The 6CG7 has a shield whereas the 6FQ7 doesn't, but in our LD's this difference doesn't matter. A number of our members have rolled these as power tubes, but found genuine 6SN7's to be better. On the other hand, if someone doesn't want to go to the trouble and expense of purchasing adapters, these are completely plug and play and fairly cheap.
 
Oct 8, 2014 at 9:13 PM Post #7,795 of 13,448
trolldragon said:
  The B+ on the LD III & IV is around 200V as well, I have not measured it specifically but all the filter caps are rated at 250V so it would not be higher or even within a few volts of that.
 
The transformer output is AC 175,  multiply by sqrt(2) to convert from RMS and that gives you approximately 247 VDC out of the full wave bridge, subtract the voltage drop from the the filtering resistors and caps you are left with a usable 200VDC
 
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Thanks for that, TD!  Looks like those with the Valhalla can have a bit of fun as we do with the LD :)
 
 
Very tempted to try the Valhalla next.....hmm...
 
Oct 8, 2014 at 9:14 PM Post #7,796 of 13,448
I have some 6CG7's & 6FQ7's but there is not a pair between them, all from different MFG's and all look different.
 
Probably would work and sound the same, BUT the Feng Shui of the amp would be broken using tubes that look different...
 
Oct 9, 2014 at 7:19 AM Post #7,798 of 13,448
Oct 9, 2014 at 7:32 AM Post #7,799 of 13,448
rossliew said:
  Would the following adapters allow me to use 6DJ8/6922/ECC88 type tubes as driver tubes with the LD Mk 3?
 
http://www.ebay.com/itm/1x-6AQ5-to-6P1-7pin-to-9pin-vacuum-tube-adapter-socket-converter-02-/290973107611?pt=Vintage_Electronics_R2&hash=item43bf59459b
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No. The 7-pin 6AQ5 and the 9-pin 6P1 are beam tetrodes. These beam tetrodes are single channel amps. The 6DJ8 is a two channel amp. It is a double triode. There are two triodes in one bottle. So you need an adapter that will distribute the two channels into two 7-pin sockets, left and right. I accomplish this rather crudely with one 9-pin breadboard socket and two Vector 7-pin test sockets.
 
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