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Rectifier Tube Rolling in a Modwight LS 36.5DM

I was hoping to get advice, I have been rolling Rectifier tubes in my two box preamp I am blown away how different tubes change the sound ,I own two sets of Mullard GZ37/CV378 a set of GE 5U4GB both vintage early 1960's and a set of stock Sovtek 5AR4 also have a NOS set of 6H30 DR I am trying in the clean  box , both the Mullard's and Dr tubes only have about  five hours of run in time but the sound seems defused on the top end ok on the bass the GE Tubes are good in the mids but soft on the highs and bass so far the stock Sovtek seems to sound best ,Dan says try 5R4-GY Tubes, any one tell me about  the Mullard's in this preamp I am getting frustrated,  thanks 
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roberjerman
4,319 posts
 
I don't know the tube complement the LS36.5 DM uses. Just thought I'd list the most common preamp tube types! 
lowrider57's avatar
lowrider57
5,417 posts
 
they would buy some from a competitor, put their own silk screen label on it, and sent it out
This happened more often than people realise. Yet another reason to buy from trusted sellers who can identify these tubes.


facten
2,881 posts
 
@robergerman
"I don't know the tube complement the LS36.5 DM uses. Just thought I'd list the most common preamp tube types! "
He listed it in his opening -  6H30 DR . 
roberjerman
4,319 posts
 
I have done some research. Apparently the 6CG7/6FQ7 will work as a substitute. Same pin-outs, similar GM and capable of 250 volts/plate. Good quality US-made ones are available for a lot less than the pricey 6N30's (correct designation). I use them in my NYAL Moscode 150.
roberjerman
4,319 posts
 
The Cyrillic "H" is actually "N" - and is pronounced that way! I can read and speak Russian!
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