trinityamps.com

Trinity Amps Guitar Amp Forum
It is currently Fri Jul 19, 2024 11:22 pm

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 5 posts ] 
Author Message
PostPosted: Thu Feb 04, 2010 1:11 am 
Offline
Friend
Friend

Joined: Thu Feb 12, 2009 11:54 am
Posts: 35
Location: San Diego, CA
I have an amp that I am working on (based on the 5F6A) which has a rectifier tube. I am looking to do away with it for size/simplicity reasons. Trying to work in another few things into the chassis and the tube rectifier holds some valuable real-estate (small chassis but amazingly quiet).

My question is... with a pair of 6L6s and a PT that's 650VCT- would it be too much to just bypass the rectifier tube and simply replace it with some diodes? Do I need an additional voltage drop now that the RT is gone? I have done a few SS rectifier designs in the past- but I am just not sure what the 6L6s can handle.

I'm sure a similar situation has been encountered in the past... if someone has got a link- just point me there and I'll be on my way.
Thanks!

Also Coco- the Tramp sounds like it's going to be killer.


Top
 Profile  
 
 Post subject:
PostPosted: Thu Feb 04, 2010 4:16 pm 
Offline
Friend
Friend

Joined: Thu Feb 12, 2009 11:54 am
Posts: 35
Location: San Diego, CA
Also... anyone have any comments on cathode bias? I am thinking about changing that to get a little more sing out of it.

Basically the amp is a fattened up version of the Bassman 5F6A "bright" channel, and the normal channel has been replaced with a Voxy/TC-15 Ef86 channel. Sounds pretty cool, but because of the fact that there is less grit coming through the power tubes (when compared to an EL84 amp)- I'd like to either add a boost or even an additional switchable gain stage to the EF86 channel... unless the cathode biased version on the poweramp gives a little more breakup (and a little drop in voltage). Good/bad idea?

As of now I have changed out the rectifier tube/socket for 4 1N5399 rectifier diodes, tying off the 5V taps. Haven't tested it yet.


Top
 Profile  
 
 Post subject:
PostPosted: Thu Feb 04, 2010 5:28 pm 
Offline
Friend
Friend

Joined: Thu Feb 12, 2009 11:54 am
Posts: 35
Location: San Diego, CA
Tested at 505V on the B+ w/out tubes. So... 360V-ish right? I'm thinking it should be fine.

But I am still curious about opinions on the cathode biased Bassman.


Top
 Profile  
 
 Post subject:
PostPosted: Thu Feb 04, 2010 6:03 pm 
Offline
Friend
Friend

Joined: Thu Feb 12, 2009 11:54 am
Posts: 35
Location: San Diego, CA
I feel like I am talking to myself... and I take pity on those who are reading this. But any help is much appreciated!

I took some measurements with and w/out tubes. But I have a problem. The plates on the 6L6s start to glow as they're hit with the B+. What could be the cause of this? I have only powered on for short periods of time as to not damage the tubes.

Measurements:

B+: 391V
OT Primary: 373V

Fliter Caps W/tubes
#1/#2 (parallel): 389V
#3: 379V
#4: 343V

Filter Caps W/out Tubes
#1/#2 (parallel): 505V
#3: 502V
#4: 498V


Top
 Profile  
 
 Post subject:
PostPosted: Sat Feb 06, 2010 1:24 am 
Offline
Friend
Friend

Joined: Thu Feb 12, 2009 11:54 am
Posts: 35
Location: San Diego, CA
Problem= crappy soldering job in the bias circuit.
Solution= start doing a better job soldering!

But it's all good now.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 5 posts ] 

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 6 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group