300bSE journey under way - 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 13th November 2010, 09:10 PM   #1
cjkpkg is offline cjkpkg  United States
diyAudio Member
 
Join Date: Aug 2008
Location: Roswell GA
Default 300bSE journey under way

Click the image to open in full size.
Click the image to open in full size.
The 300b has begun...attached is a pic of the basic layout and rough schematic. The PSU is still under development - each 300b will have its own filament xformer.

******* chassis must weigh 30lbs so far...at least...

looking forward to documenting this build...and a big shout out to this DIY community to make stuff like this possible!

Carl
  Reply With Quote
Old 13th November 2010, 09:21 PM   #2
rman is offline rman  Canada
diyAudio Member
 
rman's Avatar
 
Join Date: Oct 2007
Cool

I like the constant current draw front end. Is that inspired by John Broskie?

Cheers.
  Reply With Quote
Old 13th November 2010, 09:57 PM   #3
diyAudio Member
 
analog_sa's Avatar
 
Join Date: Aug 2002
Location: Sofia
Sufficient gain?
  Reply With Quote
Old 13th November 2010, 11:35 PM   #4
THD+N is offline THD+N  United States
diyAudio Member
 
Join Date: Jul 2007
Location: Orlando, Florida
Quote:
Originally Posted by cjkpkg View Post
Click the image to open in full size.
Click the image to open in full size.
The 300b has begun...attached is a pic of the basic layout and rough schematic. The PSU is still under development - each 300b will have its own filament xformer.

******* chassis must weigh 30lbs so far...at least...

looking forward to documenting this build...and a big shout out to this DIY community to make stuff like this possible!

Carl
Why not do the Reichert circuit? It is tried and true and you can't go wrong.
Flesh and Blood, The Reichert 300B By Herbert Reichert
  Reply With Quote
Old 14th November 2010, 05:52 AM   #5
diyAudio Member
 
analog_sa's Avatar
 
Join Date: Aug 2002
Location: Sofia
Quote:
Originally Posted by THD+N View Post
It is tried and true and you can't go wrong.


Or right. Whatever you do to that circuit it will remain mediocre. Not sure if even adding a pound of silver will help.
  Reply With Quote
Old 14th November 2010, 07:53 AM   #6
Yvesm is offline Yvesm  France
diyAudio Member
 
Yvesm's Avatar
 
Join Date: Jul 2004
Location: Ardeche
Quote:
Originally Posted by analog_sa View Post
Sufficient gain?
No ! And by far !
Computed with an axe:
- 300b needs some 140V peak to peak in its grid.
- The only voltage gain stage (half 6SN7) will hardly exceed 10
- So 14V peak to peak (near 5V rms) will be necessary on input for full output power.

Yves.
  Reply With Quote
Old 14th November 2010, 08:02 AM   #7
tomchr is offline tomchr  United States
diyAudio Member
 
tomchr's Avatar
 
Join Date: Feb 2009
Location: Greater Seattle Area
If you load the 6SN7 with a CCS, you'll get upward of 20 V/V gain in the common cathode stage. So to drive the 300B to 70 Vpeak you'd need 3.5 Vpeak (or 2.5 V RMS) on the input. I built a circuit that did that. It sounded really good. I used a source follower rather than a cathode follower for the driver stage, though.

An anode follower is another good option.

One question: How well does the circuit perform in a prototype setup? I'm assuming you built it on a peg board or something before you cut holes in the chassis...

~Tom
  Reply With Quote
Old 14th November 2010, 11:50 AM   #8
cjkpkg is offline cjkpkg  United States
diyAudio Member
 
Join Date: Aug 2008
Location: Roswell GA
honestly I have not breadboarded it up yet...I have seen so many 6sn7 front end designs around - most being anode followers though...JELabs, tmamps, diyaudioprojects.com etc...

The other thing that might be worth playing around with would be a 6sl7 up front with some minor tweaking of values...

Also I know Ill use the iron - James 6123 and allied 6k7vg. Since I have cut the holes for the iron and the tube sockets, I suppose I am stuck with octal unless I breadboard up a noval board and bolt it under the chassis.

I am assuming with some tweaking I will be happy with either a 6sn7 or 6sl7 front end. Thats the beauty of P2P right?

Last edited by cjkpkg; 14th November 2010 at 12:06 PM.
  Reply With Quote
Old 14th November 2010, 12:02 PM   #9
diyAudio Member
 
kstagger's Avatar
 
Join Date: Dec 2003
Location: Grand Rapids
diyhifisupply has a nifty 300B amp (designed by T. Loesch) that uses a pentode front end (EF86) driving a choke loaded 5687 cathode follower. That will really drive the 300B...

For my own 300B amp, I used the original "Legacy" 300B signal circuit and which has a SV83 as a driver. Results were excellent with a clean, snappy sound. Not soggy or "overly tubey" at all. Another option is the C3m or C3g.
  Reply With Quote
Old 14th November 2010, 12:52 PM   #10
THD+N is offline THD+N  United States
diyAudio Member
 
Join Date: Jul 2007
Location: Orlando, Florida
Quote:
Originally Posted by analog_sa View Post
Or right. Whatever you do to that circuit it will remain mediocre. Not sure if even adding a pound of silver will help.
I figured someone would post a useless reply...
  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
My new Journey N7XG Chipamp 10 12th February 2010 06:56 PM
Which amp/speaker combo? 300Bse + FE126/206/166E or Solid State + Jordan JX92S cangaceiro99 Full Range 11 5th May 2006 11:17 AM
300BSE power amplifier circuit ashawn Tubes / Valves 5 26th February 2005 07:18 PM
300BSE series meandrew Tubes / Valves 3 14th April 2004 09:56 AM
The journey begins... Mos Fetish Multi-Way 2 14th January 2004 01:02 PM


New To Site? Need Help?

All times are GMT. The time now is 10:59 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