Re: [Harp-L] Premier 50

[MARK BURNESS <markwjburness@xxxxxxxxxxxxxx>]

If the amp has 450vdc on the plate with a 6L6, I wouldn't go for the 6V6, less 
heater current draw & less plate current draw will see that voltage rise 
further...JJ 6V6 will take the voltage, probably EH too, but I wouldn't use NOS 
6V6.




________________________________
From: Dan Fritz <bluesharp@xxxxxxxxxxx>
To: MARK BURNESS <markwjburness@xxxxxxxxxxxxxx>
Sent: Wednesday, 5 January, 2011 19:05:02
Subject: Re: [Harp-L] Premier 50


Thanks, Mark,
 
I thought abut changing the power tube to a 6V6 and going with the smaller 
transformer, and may end up doing that down the road.  My tech says the amp will 
produce 10-12 watts as configured ("...this amp has a 6L6 and a B+ voltage of 
about 450v. I believe it needs something capable of about 12 watts.").
 
Maybe it won't actually put out that much, but I think it will 
substantially exceed 5 watts.  I think that's why the transformer that's in it 
blew...
 
Here's what Keith Graham wrote me this a.m.:
 
The early 50s were all 6v6, but the late 50s and 1960s ones had a 6L6.
You can buy a champ output transformer and use a 6V6. There is a champ
upgrade transformer that will take the higher amps of a 6L6 that you
can get also. I've never heard one of these in action and I wonder how
they work since there may be some impedance matching issues. I would
think that a 6V6 might not have as much gravel and overdrive using
this transformer. A smoother tone might be good for harp.

http://www.triodeelectronics.com/40-18031.html

Keith
 
I have ordered the beefier transformer from Triode Electronics, and I will let 
the group know how it sounds.
 
Thanks again for your response and advice!
 
-Dan
 
 
 
----- Original Message ----- 
From: MARK BURNESS 
>To: Dan Fritz ; harp-l@xxxxxxxxxx 
>Sent: Wednesday, January 05, 2011 10:50 AM
>Subject: Re: [Harp-L] Premier 50
>
>
>That amp won't make 12W, irrespective of whether you fit a 6V6 or 6L6. Check the 
>power tube pinout/tube chart, just in case it was originally intended for 7591A 
>use (they used 4 different power tubes over the years, 7591A has the large high 
>Wattage 150ohm cathode resistor at pin 5, 6V6/6L6 have it on pin 8 and at a 
>larger value in ohms).
>
>A 5K SE output transformer would be fine for either 6L6 or 6V6, so long as it is 
>rated for <70mA you should be fine. Allen amps or Kendrick will have overrated 
>Champ style OTs for 6L6 or 6V6 use. There are also a couple of Hammond OTs that 
>would work fine, but be aware that these might be considerably larger than the 
>original, so check out mounting centres.
>
>Alternatively, as you note, a champ 6V6 OT  will work fine, be easier on the 
>power transformer, but these are meant for a 4ohm load, not an 8ohm speaker 
>(some vendors sell multi tap versions).
>
>I wouldn't get too hung up on having the exact spec part.
>
>
>
________________________________
From: Dan Fritz <bluesharp@xxxxxxxxxxx>
>To: harp-l@xxxxxxxxxx
>Sent: Wednesday, 5 January, 2011 17:29:00
>Subject: [Harp-L] Premier 50
>
>Hi, all, 
>I have a 1956 or so Premier 50 with an 8 ohm Utah speaker that came to me with a 
>blown output transformer.  It also came loaded with a 6L6 power tube.  I am 
>thinking that perhaps the prior owner swapped a 6L6 for a 6V6 and that the 
>additional output blew the transformer.  I can't readily find a replacement 
>transformer with the right primary wind resistance (3K to 5K) that can handle a 
>12 watt output.  I'm wondering if the 6L6 tube is just wrong for the amp, and if 
>I should just get a "champ-style" 5 watt-capable transformer and run a 6V6, or 
>whether the 6V6 is the right power tube and I need to keep seeking a 
>sufficiently robust output transformer.
>Any Premier 50 experts out there want to chime in?
>Thanks!
>
>-Dan
>