My Tubelab SE unanswered question - diyAudio
Go Back   Home > Forums > Commercial Sector > Vendor Forums > Tubelab

Tubelab Discussion and support of Tubelab products, prototypes and experiments

Reply
 
Thread Tools Search this Thread
Old 4th August 2011, 02:32 PM   #1
diyAudio Member
 
Join Date: Nov 2009
Location: Vienna
Default My Tubelab SE unanswered question

Dear All,

I'd like in my new Tubelab SE to reduce the voltage for the power drive to 200V to limit the heat consumption.

The question is: how much current should I make available ? I tried to measure, but it looks like the current drain is almost zero.

Thanks,

Davide
  Reply With Quote
Old 4th August 2011, 03:30 PM   #2
diyAudio Member
 
tubelab.com's Avatar
 
Join Date: Jul 2005
Location: West Virginia panhandle
The average current drain is set by the resistor from the source of the fet to the negative supply. I usually aim for 5 to 10 mA to limit dissipation in the mosfets. If your positive voltage supply is lower, then you can increase the current to improve the dynamics a bit. I have found no benefit to going beyond 20 or 25 mA. These current numbers are per channel.

For my test amps, I use an isolation transformer with two 120 volt secondaries which I put in series. With a bridge rectifier and filter I get a +/- 160 volt supply for PowerDrive. That works well.
__________________
Too much power is almost enough! Turn it up till it explodes - then back up just a little.
  Reply With Quote
Old 6th August 2011, 06:48 AM   #3
diyAudio Member
 
Join Date: Nov 2009
Location: Vienna
Thanks!!! I will be using the regulator from diyhifisuppy, that has -120v supply. For the positive suppy of the powerdrive i will use a secondary winding of the main transformer. As I will have it custom made, i will request 50mA 150v. That should make.

We will see what will come out.

Davide
  Reply With Quote
Old 21st August 2011, 04:38 PM   #4
diyAudio Member
 
Join Date: Nov 2009
Location: Vienna
George,

Another question: what filament voltage are you aiming for the 5842 tubes ? I notice that with the current arrangement it is below 6.3 V. Do you think there is any advantage to run a separate filament supply for the drivers ?

Thanks,

Davide
  Reply With Quote
Old 22nd August 2011, 12:10 AM   #5
diyAudio Member
 
tubelab.com's Avatar
 
Join Date: Jul 2005
Location: West Virginia panhandle
Quote:
Another question: what filament voltage are you aiming for the 5842 tubes ? I notice that with the current arrangement it is below 6.3 V
I aim for 6.3 volts. The 5842 is the most variable tube that I have ever used and that includes the heater current. I have seen 5.4 to 6.7 volts with the stock configuration. The 5842 heater voltage depends on the power line voltage and tube current. I usually just tweak R3 as needed.

If you were building the ultimate amplifier with off board power supplies a good DC source for the 5842's might be a good idea. I did that in my 845SE amp which used a Tubelab SE for the driver.
__________________
Too much power is almost enough! Turn it up till it explodes - then back up just a little.
  Reply With Quote
Old 22nd August 2011, 11:38 AM   #6
diyAudio Member
 
Join Date: Nov 2009
Location: Vienna
Will do like this.

Then I think it makes sense also to lower the AC for the 300B filament, so I reduce the heat production of the regulator. Am I correct ?

Thanks,

D.
  Reply With Quote
Old 23rd August 2011, 03:12 AM   #7
diyAudio Member
 
Join Date: Nov 2009
Location: Vienna
As I am pretty flexible with the power supply at this stage I was thinking something like this.

The module that I am using needs the rectifier, so I am using the rectifier on board, mainly to hold the tube in place.
The output of the module will be +400V and -120V. The B+ from the module should be mainly ripple free.
I will have a separate supply CRC for the power drive.

Now I can feed the B+ directly to the OT and feed the board with the power drive supply of around 200V. Like this the drivers and the power drive will share the supply, and I will reduce the heat also on the CCS.

The disadvantage is that the driver will not have a supply as clean as the power tube, but I noticed that the CCS makes his own work to reduce ripple.

Am I correct ? Does it make sense ?

For the filament, I will use the on-board supply for the 300B, feed with something around 5.5VAC and a separate PSU feeding 6.3 V 0.8 A regulated to the drives. I will have an ACof around 7VAC.

Please comment on my plan. Maybe I am missing something.

Thanks,

Davide
  Reply With Quote
Old 23rd August 2011, 03:18 AM   #8
diyAudio Member
 
Join Date: Nov 2009
Location: Vienna
And the other disadvantage is that the drivers will be feed with a supply done with diodes rectification, not tube.

D.
  Reply With Quote
Old 26th August 2011, 11:30 PM   #9
diyAudio Member
 
Join Date: Nov 2009
Location: Vienna
Any input?

Thanks,

Davide
  Reply With Quote
Old 30th August 2011, 05:35 AM   #10
diyAudio Member
 
Join Date: Nov 2009
Location: Vienna
So I think I will use the separate supply only for the mosfet. I set on 160 VAC 220uF 270R 220uF. Does it make sense here to have something like PP caps at the output, let's say 10uF or something smaller.

Additionally, I have two ammeter to connect instead of the resistors. Now they will be directly in the signal path. Should they bother me ?

I plan to connect one pp cap for each channel right at the OT. I think this should mitigate any possible negative effect of the meter. Am I correct ?

Thanks,

Davide
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Tubelab SE vs Simple SE Pez Tubelab 25 29th October 2011 02:16 AM
Tubelab SE 2A3 _ Newbie question. btran Tubes / Valves 14 21st November 2009 01:28 AM
Tubelab SE amp question smbrown Tubes / Valves 8 21st September 2009 05:05 PM
tubelab se DimZ Tubelab 58 20th January 2009 12:47 PM


New To Site? Need Help?

All times are GMT. The time now is 12:43 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2