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Little Dot Tube Amps: Vacuum Tube Rolling Guide
Mar 18, 2014 at 4:44 PM Post #5,461 of 13,434
I have not sign in for a few days and i missed a lot.
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Mar 18, 2014 at 10:05 PM Post #5,463 of 13,434
So my 6SN7 love has spread to my Lyr... I ordered some adapters and materials to start butchering that amp too.
 
Mar 18, 2014 at 10:20 PM Post #5,464 of 13,434
kvtaco17 said:
  So my 6SN7 love has spread to my Lyr... I ordered some adapters and materials to start butchering that amp too.
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I will be very interested in your observations. In searching the Lyr threads some time ago, I found that 6CG7s had been tried, and those few who posted felt that the Lyr was designed so tightly arround 6DJ8s, that it couldn't bias 6CG7s properly....
 
Mar 18, 2014 at 10:28 PM Post #5,465 of 13,434
gibosi said:
   
I will be very interested in your observations. In searching the Lyr threads some time ago, I found that 6CG7s had been tried, and those few who posted felt that the Lyr was designed so tightly arround 6DJ8s, that it couldn't bias 6CG7s properly....
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I've been following that tread since I got my Lyr and I never remember seeing that discussion... I'll go dig some more before I chase this...
 
Found it! So it has a 200V rail... I need like 400V to be in spec and to get control of the tubes... I supposed I'll have to investigate building a new circuit to power them...
 
Mar 18, 2014 at 10:39 PM Post #5,466 of 13,434
kvtaco17 said:
  I've been following that tread since I got my Lyr and I never remember seeing that discussion... I'll go dig some more before I chase this...
 
Found it! So it has a 200V rail... I need like 400V to be in spec and to get control of the tubes... I supposed I'll have to investigate building a new circuit to power them...
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But I wonder about that...   I am pretty sure our LDs have 200V rails?
 
Mar 18, 2014 at 11:19 PM Post #5,467 of 13,434
kvtaco17 said:
I've been following that tread since I got my Lyr and I never remember seeing that discussion... I'll go dig some more before I chase this...

Found it! So it has a 200V rail... I need like 400V to be in spec and to get control of the tubes... I supposed I'll have to investigate building a new circuit to power them...
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That would require a complete new HV power supply... New transformer, caps, resistors. I'd look for an amp that takes 6SN7's as default, it would be cheaper IMHO.

The little single tube hybrid I have for review takes a 6922, some of my 6DJ8's distort in it and it is a biasing issue. I crank up the trim pots and I can get the odd 6DJ8's to play nice. If I changed the cathode resistors I could probably get the 6H9C to work without distortion like it has now.

I'd look into biasing if you have issues with the 6SN7 in the lyr, but I am just guessing. There is nothing as versatile as the Little Dot for rolling many different tubes, except for that Garage1217 plastic case stuff, which is just butt ugly in my opinion. :D
 
Mar 18, 2014 at 11:21 PM Post #5,468 of 13,434
The other thing is the little single tube hybrid runs the 6922 at 5V on the plate, so I don't think you really need 400V... :D
 
Mar 19, 2014 at 2:50 AM Post #5,469 of 13,434
trolldragon said:
The other thing is the little single tube hybrid runs the 6922 at 5V on the plate, so I don't think you really need 400V...
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5V on the plate? 
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 No wonder if there is easily distortion. It's a miracle that it is possible to get any sound through with voltages like that. And i have been thinking, that under 50v between plate and cathode is no good.
 
Mar 19, 2014 at 6:45 AM Post #5,470 of 13,434
trolldragon said:
That would require a complete new HV power supply... New transformer, caps, resistors. I'd look for an amp that takes 6SN7's as default, it would be cheaper IMHO.

The little single tube hybrid I have for review takes a 6922, some of my 6DJ8's distort in it and it is a biasing issue. I crank up the trim pots and I can get the odd 6DJ8's to play nice. If I changed the cathode resistors I could probably get the 6H9C to work without distortion like it has now.

I'd look into biasing if you have issues with the 6SN7 in the lyr, but I am just guessing. There is nothing as versatile as the Little Dot for rolling many different tubes, except for that Garage1217 plastic case stuff, which is just butt ugly in my opinion.
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Don't ruin my dreams lol
 
Mar 19, 2014 at 1:12 PM Post #5,471 of 13,434
Well folks, I'm half-way through the 100 hr burn-in of the Psvanes + adapters, and last night (at 35hrs) I had a minor unpleasant shock - the changes that can take place during burn-in certainly are VERY interesting/strange, but with these the 35hr mark was the strangest I have ever encountered. From  apparent (almost) perfection straight out of the box -  and trouncing of the 6N30P-DRs -  I was presented with something very worrying (for me at least)...too much of the classic "warm/soft/tubey" sound. I know many people go to tubes just for that very reason, but I myself prefer what some consider "cool/analytical/too(?) much detail". I find this generally brings a greater sense of clarity, instrument/voice separation, and 3-dimensional sound stage. And those wonderful micro details and transients can be so magical (given a sound engineer who knows what they are doing!). Well, these qualities I love had almost disappeared! Bass and (instrumental) mids had come to the fore (which I am sure would have delighted many!), but at the expense of what I love - and certain vocals were pushed further away - horror of horrors! My anguish was heightened by the possible appearance of unwelcome 'extras' related to the "tuning for greater upper frequencies". But I was at least spared this nasty surprise...
 
Needless to say I didn't sleep well last night!...I know I should have known better, but never having encountered such an about-face before I was caught off-guard...Thankfully, a further 16hrs have brought another transformation - I'm a happy chappie once more. All that I crave has returned - balance is restored, and the DRs have suffered another KO. Once again the Psvanes at the very  least match the DRs, and now especially, surpass them in most areas...and the newly-tamed bass is truly delicious. To paraphrase a review on 6SN7s, the Psvanes are to the DRs what the Sylvania 6SN7GT "Bad Boys" are to their VT231s - viz the latter being heaven from the bottom up, but the Bad Boys even more so, and with uber-divine bass!
 
So tonight I shall sleep more soundly....just hope there are no more nasty about-turns, lol!!!
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Mar 19, 2014 at 1:40 PM Post #5,472 of 13,434
Mar 19, 2014 at 2:35 PM Post #5,474 of 13,434
Hi,
 
If you don't need to impress ur friends with the Telefunken logo, you could buy these 6922 tubes made in the same factory for roughly 70% less ($42 vs $12):
 
https://tubedepot.com/products/jj-e88cc-6922-preamp-vacuum-tube?gclid=CJ7Rq6idn70CFfNxOgodqHUA6w
 
Mar 19, 2014 at 2:41 PM Post #5,475 of 13,434
mordy said:
  Hi,
 
If you don't need to impress ur friends with the Telefunken logo, you could buy these 6922 tubes made in the same factory for roughly 70% less ($42 vs $12):
 
https://tubedepot.com/products/jj-e88cc-6922-preamp-vacuum-tube?gclid=CJ7Rq6idn70CFfNxOgodqHUA6w
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So the JJ's are the same as the Black Diamonds?
 
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