6N30P for high voltage - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 14th September 2002, 12:07 AM   #1
diyAudio Member
 
Join Date: Jan 2001
Location: Scandinavia
Default 6N30P for high voltage

Hi again,

I am stuck trying to choose between tubes driving my DC coupled OTL Stax Headphone amp. After evaluating various topologies over the past few years , the configuration will be p-channel cascoded input stage driving a stage with a parallell configuration. I am wondering which tube to use.

My hope was to use the 6N30P at about 10mA per side with 5 tubes in parallell, but I realize the voltages are a little high. Another alternative I have is to go with 6S4.

Any comments on tube choice? Stage shown is balanced long tailed pair with output taken at zero volts.

Petter
Attached Images
File Type: gif stage2.gif (9.4 KB, 956 views)
  Reply With Quote
Old 14th September 2002, 08:11 AM   #2
diyAudio Member
 
Join Date: Dec 2000
Location: Germany
Default stax

Stax has used the 6CG7/6FQ7 in nearly every headphone amp. In their big two peace unit
for the OMEGA they use EL34`s.

Think you can also use 6SN7 but why donīt you give the H30 a try.

Reinhard
  Reply With Quote
Old 14th September 2002, 06:13 PM   #3
diyAudio Member
 
Join Date: Jan 2001
Location: Scandinavia
Thanks Reihard

Since the datasheet does not cover high voltage, I am uncertain about whether to go for it or not. I probably will. Perhaps I will even do the full monkey (use each half of an H30 as cascode for a 2SK170 JFET) ...

Single stage JFET input OTL stage.

Do you have schematics for the EL34 Stax unit?

Petter
  Reply With Quote
Old 15th September 2002, 06:44 AM   #4
diyAudio Member
 
Brett's Avatar
 
Join Date: Jan 2002
Petter,

I also have a STAX phone amp scheduled as a future project. Mine is at a very early stage of 'blue-skying' ideas at present.

The data I have indicates max DC plate voltage is 250V, with a 400Vh-k limit. But why would you want to use 5 6H30's in parallel? Especially at 10mA, where they're not even that linear or good sounding.

You don't need that much drive current and about 350Vp-p to produce very high levels. John Broskie of Tubecad uses 5965's as output in his, and he's no fool. Why not try them or a 6BX7, ECC99, 12B4A, trioded 7189A or if you must EL34?

The STAX schematic with 6CG7/6FQ7 can be found <a href="http://www.bonavolta.ch/hobby/en/audio/hdgsta.htm">here</a>

If you haven't already seen the Tubecad articles, they're well worth a read. Can be found in the 99 archives. There are also a couple of Kevin Gilmore designs at Headwize.

Cheers
Brett
  Reply With Quote
Old 15th September 2002, 06:54 AM   #5
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Blog Entries: 5
Quote:
Originally posted by Petter
full monkey
You aren't talking about this full monkey are you?

Click the image to open in full size.

dave
__________________
community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi
p10-hifi forum here at diyA
  Reply With Quote
Old 15th September 2002, 08:33 AM   #6
diyAudio Member
 
Join Date: Jan 2001
Location: Scandinavia
Default Not really, but close ...

So the full monkey setup I am looking at is conceptually the same as Thorsten's. If you look into his original work, he has progressed to JFET "monkey device".
Attached Images
File Type: gif monkey.gif (5.2 KB, 552 views)
  Reply With Quote
Old 15th September 2002, 09:13 AM   #7
diyAudio Member
 
Join Date: Jan 2001
Location: Scandinavia
Default Drive current

Thanks, Brett!

I am familiar with the sources you mentioned except the link to the Stax amp. I used to own a SRM-T1, and it was awesome, except that it was quite obvious that the tubes were working overtime.

I should have gone to a direct drive OTL 300B from the start, but now that the cabinet is built (with teflon sockets and all), it is kind of hard to go back for this version.

As far as output current goes, I have calculated that I need about 7.5mA current phase to phase. This means that I probably should have significantly more! So parallell small signal tubes (9 pin sockets) seems to be the order of the day.

So this is what I will likely do:

Option 1: Use a 12AX7 or more likely 6N30P as a folded cascode in stage 1, driving parallell 6S4 outputs (2 6S4 units per phase). This is DC coupled and if I use a 6N30P for the input, it can be run at say 30mA per phase in a balanced LTP configuration. Input stage voltage gain 30 times per phase, output stage with low gain (5-10 times per phase) and thus low output impedance.

Option 2: Use a p-JFET monkey input stage with cascode driving the same output

Option 3: Use a n-JFET monkey into the 6S4's and take the output at +300V mean.

I originally planned to do as per attached document (now somewhat out of date but still pretty cool as an X-Stax Pass type unit). (Sorry 100K limit causes this 350K zipped 8 page word design document to be put elsewhere, I don't know where yet)

Petter
  Reply With Quote
Old 7th April 2012, 01:00 PM   #8
AJT is offline AJT  Philippines
diyAudio Moderator
 
AJT's Avatar
 
Join Date: May 2003
Location: Palatiw, Pasig City
any updates?
__________________
the best advertisement for a good audio design is the number of diy'ers wanting to build it after all the years....never the say so of so called gurus....
  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
High voltage, high current super regulator, possible group buy peranders Group Buys 54 2nd June 2009 09:43 AM
Wanted - High Power, High Voltage, Audio Frequency Transformer Manual. kimbal Tubes / Valves 4 11th May 2009 08:05 PM
high frequency high voltage power supply... moray james Planars & Exotics 6 23rd July 2008 07:57 PM
6BY5 High Voltage & High Current Choke Input Design P.S. snoopyma Tubes / Valves 7 28th June 2006 01:32 PM


New To Site? Need Help?

All times are GMT. The time now is 11:16 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright Đ1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2