|
Post by doveman on May 24, 2012 14:39:26 GMT -7
Finished rewiring my 2x12 cab ... mounting the Brake Lite in there ... buttoning everything on the amp back up. Before I put the back screen on the head, I decided to pop in the 5U4GB. I knew from yesterday that I could not actually set the bias as high as it might call for ... but since I juiced up the 5AR4 and replaced the 12AX7 ... what the hell. Man that's nice too. I imagine it's running at about 55%-60% with the currrent bias setting for the 5AR4 ... but real nice. Very smooth and a log of sag and touch sensitivity. Glad I tried it again. We are cooking with gas now ... with either one.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on May 25, 2012 9:56:47 GMT -7
Switch out the bias resistor.
You are sitting pretty good where it is biased. I used to like my Route as close to 70% as I could get 'er. Of course you will get drift over time. You'll get some great tones w/out the brake and the Route cranked, jmho.
|
|
|
Post by doveman on May 25, 2012 15:06:20 GMT -7
Switch out the bias resistor. You are sitting pretty good where it is biased. I used to like my Route as close to 70% as I could get 'er. Of course you will get drift over time. You'll get some great tones w/out the brake and the Route cranked, jmho. I cranked it up again today ... I think I liked the 5AR4 just a bit better cranked up. But I really like the feel of the 5U4GB when I turn it back down a bit. I'm a real fan of a little more "sag" for my playing style. I think if I could tweak it up just a little more on the 5U4GB, it would be the best. I had a bit more room on the pot currently, but it's set for 70% on the 5AR4. I have a few electronics parts coming from Mouser ... threw in those 1% 2W 1-ohm Vishay resistors on the order. So when they get here I'll fix the bias points for good. I might tweak it on up a bit more with the 5U4GB and test it loud before I put the chassis back in the head cab. In the end, more sag and less volume of the 5U4GB would suit my playing style a bit better ... I think. Good news is I could record with it the way it is ... might do a little recording this weekend ... I'm getting the itch to write something new and record it.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on May 25, 2012 18:05:09 GMT -7
Good news is I could record with it the way it is ... might do a little recording this weekend ... I'm getting the itch to write something new and record it. That's great news. I hope you post something here on the forum.
|
|
|
Post by doveman on May 29, 2012 17:15:09 GMT -7
Switch out the bias resistor. You are sitting pretty good where it is biased. I used to like my Route as close to 70% as I could get 'er. Of course you will get drift over time. You'll get some great tones w/out the brake and the Route cranked, jmho. Hey Doc ... my 1-ohm resistors will show up tomorrow. In the above quote, you said I was sitting pretty good where it was biased. I had mentioned that the current pot setting was about 70% @ 37 mA for the 5AR4 while about 55-60% @ 31-32 mA for the 5U4GB. Did you mean that I should get as close to 70% as I could with the 5U4GB or it was good at maybe 55-60% dissipation? I'll get another look at it tomorrow when I break the chassis out to swtich out the resistors. I'll try to do it by ear, as well ... somewhere between 50%-70% with it cranked and the BL engaged so I don't lose my hearing. Still like what I hear when it's lower in volume but cranked up it loses something for me still. BTW ... I did put the 12AX7LPS back in ... all of the improvement so far came from the biasing alone.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on May 29, 2012 18:33:27 GMT -7
Switch out the bias resistor. You are sitting pretty good where it is biased. I used to like my Route as close to 70% as I could get 'er. Of course you will get drift over time. You'll get some great tones w/out the brake and the Route cranked, jmho. Hey Doc ... my 1-ohm resistors will show up tomorrow. In the above quote, you said I was sitting pretty good where it was biased. I had mentioned that the current pot setting was about 70% @ 37 mA for the 5AR4 while about 55-60% @ 31-32 mA for the 5U4GB. Did you mean that I should get as close to 70% as I could with the 5U4GB or it was good at maybe 55-60% dissipation? I'll get another look at it tomorrow when I break the chassis out to swtich out the resistors. I'll try to do it by ear, as well ... somewhere between 50%-70% with it cranked and the BL engaged so I don't lose my hearing. Still like what I hear when it's lower in volume but cranked up it loses something for me still. BTW ... I did put the 12AX7LPS back in ... all of the improvement so far came from the biasing alone. I just meant that it was not in a "bad" spot as far as bias. I liked my Route as close to 70% as I could get it. Sometimes I would run it at 70-75%. Your ears might prefer it right where it is. It's like the 12ax7lps was made for that amp. Or maybe visa-versa. As Doc designs w/current production tubes in mind. A man ahead of his time, he is.
|
|
|
Post by doveman on May 30, 2012 17:42:06 GMT -7
OK ... new bias points installed ... before I moved anything I measured ... - 5AR4 - 462VDC - set at 38.4 mA - 70.9% dissipation
- 5U4GB - 440VDC - set at 27.7 mA - 48.8% dissipation
Going to run the 5U4GB with the bias pot dimed ... - 5U4GB - 428VDC - set at 31.9 mA - 54.6% dissipation
Definitely less volume with this rectifier ... softer edges ... more sag ... looser. Will play it like this for a few days. I cannot just slip the 5A4R back in there without rebiasing now. I like having the accurate and handy bias points too.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on May 30, 2012 18:11:31 GMT -7
OK ... new bias points installed ... before I moved anything I measured ... - 5AR4 - 462VDC - set at 38.4 mA - 70.9% dissipation
- 5U4GB - 440VDC - set at 27.7 mA - 48.8% dissipation
Going to run the 5U4GB with the bias pot dimed ... - 5U4GB - 428VDC - set at 31.9 mA - 54.6% dissipation
Definitely less volume with this rectifier ... softer edges ... more sag ... looser. Will play it like this for a few days. I cannot just slip the 5A4R back in there without rebiasing now. I like having the accurate and handy bias points too. The re-issue Gold Lion is a 30 watt tube. If that is the output tube you are using then your numbers need to be adjusted. 462VDC @ 60%=39mA, 70%=45mA 440VDC @ 60%=41mA, 70%=48mA 428VDC @ 60%=42mA, 70%=49mA W/the bias pot dimed, using the 5u4gb, you are running well below 50% of plate dissipation. Too, cold imho. Here is a link to a conversation which I had with, Myles about the reissue Gold Lions. ztalk.proboards.com/index.cgi?board=xperts&action=display&thread=11242&page=46
|
|
|
Post by doveman on May 30, 2012 18:47:01 GMT -7
My KT66 appear to be Groove Tube #5 tubes. Not sure who makes them for GT.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on May 30, 2012 19:10:54 GMT -7
K.
I thought I read in another thread that you were gonna be using the Gold Lions.
You are fine then. The Groove Tubes are 25 watt tubes.
They were a russian made tube. I believe they were designed w/the assistance of Mike Zaite for use in the Route 66.
|
|
|
Post by doveman on May 30, 2012 19:16:55 GMT -7
I did mention that I wanted to get a backup set of tubes and was considering the Gold Lions. But I'm not sure I can dial up the bias enough to handle them. I kind of like the other suggestion ... getting some of these same tubes with maybe a #7 rating as my extra tubes.
I'm learning a lot about the "ins and outs" of this amp though ... so keep shooting the info to me. I figure in another week or so I'll have this guy dialed in pretty close.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on May 30, 2012 19:25:55 GMT -7
Good luck finding more. There were problems at the factory and they "lost" the tooling for those tubes quite awhile ago.
|
|