Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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

45 amp build direct coupled
45 amp build direct coupled
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 22nd March 2018, 01:40 PM   #11
pieter t is offline pieter t  Netherlands
Account disabled at member's request
 
Join Date: Apr 2009
Quote:
Originally Posted by audiowize View Post
If you're using a 5K transformer, very few of them have sufficient inductance to give satisfying bass performance.
Then it is not a 5k transformer
  Reply With Quote
Old 22nd March 2018, 02:25 PM   #12
audiowize is offline audiowize  United States
diyAudio Member
 
Join Date: Aug 2005
Location: Seattle
Send a message via AIM to audiowize
The 4.4K resistor needs to be a whole heck of a lot bigger than 10W, I would look for at least 20W. You also have two parallel feed caps. You can return the bottom of the primary of the output transformer to the top of the cathode bias resistor.
  Reply With Quote
Old 22nd March 2018, 08:29 PM   #13
6A3sUMMER is offline 6A3sUMMER  United States
diyAudio Member
 
Join Date: Jun 2016
You swapped the Emitter and Collector connections in the updated schematic. The Collector needs to be connected to the plate of the tube.
And the transistor is a PNP, the arrow of the Emitter needs to point into the transistor.

You do not want the Emitter of a transistor to be the plate load for the input tube
(Emitters are low impedance).

Last edited by 6A3sUMMER; 22nd March 2018 at 08:46 PM.
  Reply With Quote
Old 23rd March 2018, 06:23 AM   #14
faithintruth is offline faithintruth  Canada
diyAudio Member
 
Join Date: Feb 2012
Hi 6A3sUMMER
Attached Images
File Type: jpg 20180323_151907.jpg (603.9 KB, 333 views)
  Reply With Quote
Old 23rd March 2018, 11:42 AM   #15
euro21 is offline euro21  Hungary
diyAudio Member
 
Join Date: Sep 2004
Location: Budapest
45 amp build direct coupled
IMHO 300V B+ is too low for this circuit.
Attached Images
File Type: jpg D3a cCCS, direct 45 parafeed SE.jpg (77.6 KB, 321 views)
  Reply With Quote
Old 23rd March 2018, 12:10 PM   #16
mbrennwa is offline mbrennwa  Switzerland
diyAudio Member
 
mbrennwa's Avatar
 
Join Date: Mar 2005
Location: Zurich, Switzerland
Looks yummy! How about battery (NiMH) bias instead of the LED bias?
__________________
[ audioroot.net | hifibau.ch ]
  Reply With Quote
Old 23rd March 2018, 01:01 PM   #17
euro21 is offline euro21  Hungary
diyAudio Member
 
Join Date: Sep 2004
Location: Budapest
45 amp build direct coupled
Quote:
Originally Posted by mbrennwa View Post
How about battery (NiMH) bias instead of the LED bias?
NiMH cell has 1.2V, so two in series has too much voltage.
At 2.4V bias the D3a anode voltage rising over 210-215V, so the operating point moving to the -more- non-linear region and accessible swing is significantly decrease.
  Reply With Quote
Old 23rd March 2018, 04:44 PM   #18
mbrennwa is offline mbrennwa  Switzerland
diyAudio Member
 
mbrennwa's Avatar
 
Join Date: Mar 2005
Location: Zurich, Switzerland
I just said NiMH because this type has the lowest dynamic resistance I believe. Other battery types may provide a better biasing voltage. But heck, the whole battery bias thing was just a wild idea that would be easy to try instead of the LEDs (I did in another amp, and I liked it). No big deal.
__________________
[ audioroot.net | hifibau.ch ]
  Reply With Quote
Old 24th March 2018, 08:54 AM   #19
soulmerchant is offline soulmerchant  Switzerland
diyAudio Member
 
soulmerchant's Avatar
 
Join Date: Sep 2006
Location: Near Zurich
I would consider a gyrator load with non-inductive film resistor on the cathode (caddock). Also D3a could be replaced with other triode strapped pentodes.

E180F, E280F and 7788 should all be up to the task and are a little more obtainable these days.
  Reply With Quote
Old 24th March 2018, 01:41 PM   #20
faithintruth is offline faithintruth  Canada
diyAudio Member
 
Join Date: Feb 2012
Wow....800 views may indicate a group build. If possible I'd like to stick to a high mu driver, ccs, parafeed....optimizing the current amp with fewer major changes. Any help with values would be great. Brands of parts have not been settled. I'm not married to a particular smoothing cap. Bill Epstein described Obigato magic and insisted on tube rectification.

In short I'm not a designer. The schematic has already been a collaboration. Draw me the gyrator and let's see what others think but I was intending to stick closer to the original circuit.

I have attached Tucker's drawing here
Attached Images
File Type: png pastedImage.png (217.1 KB, 260 views)
  Reply With Quote

Reply


45 amp build direct coupledHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Direct Coupled Amp kianbach Tubes / Valves 1 8th January 2012 09:05 PM
capacitor coupled vs. direct coupled ouput hugobross Solid State 11 21st January 2011 01:56 AM
6sn7 direct coupled and transformer coupled neazoi Tubes / Valves 3 23rd May 2008 03:30 PM
My first amp - a direct coupled 2A3 Wardsweb Tubes / Valves 51 3rd August 2003 04:22 AM
Can someone explain parafeed & direct coupled & a.c. coupled? mwmitchell Tubes / Valves 2 11th September 2002 01:10 PM


New To Site? Need Help?

All times are GMT. The time now is 08:02 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki