West Mini IR rebuild - Page 3 - diyAudio
Go Back   Home > Forums > Live Sound > Instruments and Amps

Instruments and Amps Everything that makes music, Especially including instrument amps.

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 17th April 2012, 02:28 PM   #21
shanx is offline shanx  Canada
diyAudio Member
 
Join Date: Dec 2010
Location: Quebec
The lucky break was trying out the 12AX7 on the PI before I put the MV control in. The 12 AX7 brought gain up and was saturating earlier, gave me a feel for how it would sound cranked up.I had planned on putting the MV as a trial anyways , but with the 12AX7 in there it became almost a necessity. Without the MV I think I could trash the speaker, literally bottom it out the coil at peak transitions. I have a Fender Blues Junior with the volume and master volume, and I liked that layout.
  Reply With Quote
Old 17th April 2012, 03:16 PM   #22
Simon B is offline Simon B  United Kingdom
diyAudio Member
 
Join Date: Dec 2011
Location: North-East England
Well be a star, draw up your revised schematic and give us what we want:

Fresh Valve Amp Porn!
  Reply With Quote
Old 18th April 2012, 06:14 PM   #23
shanx is offline shanx  Canada
diyAudio Member
 
Join Date: Dec 2010
Location: Quebec
Default Master Vol & Attenuator

OK, SimonB I submit this: what has been done for the MV etc, and planning for the attenuator. I want a simple control of the overall amp volume, and with the attenuator I hope to get a bit more drive from the power amp circuit whilst not blowing out any speakers
IS THIS NSFW??
Attached Images
File Type: jpg Avalon_Mini IR mods.JPG (95.6 KB, 26 views)
  Reply With Quote
Old 18th April 2012, 06:26 PM   #24
shanx is offline shanx  Canada
diyAudio Member
 
Join Date: Dec 2010
Location: Quebec
Note added benefit of building in attenuator: If I get forgetful about plugging a speaker in, with the switched jack I will save myself an OT.
I probably need to parallel another resistor in case a speaker blows. Add to the list..
  Reply With Quote
Old 18th April 2012, 06:53 PM   #25
Simon B is offline Simon B  United Kingdom
diyAudio Member
 
Join Date: Dec 2011
Location: North-East England
Quote:
Originally Posted by shanx View Post
IS THIS NSFW??


Oh Yes Mrs!
  Reply With Quote
Old 18th April 2012, 07:29 PM   #26
shanx is offline shanx  Canada
diyAudio Member
 
Join Date: Dec 2010
Location: Quebec
Have fun tonight!
I am going to order up the power resistors for the attenuator, and still have to decide on whether to try a circuit scaling the plate volts and readjust bias.This amp does not have the adjustment pot for the biasing, just fixed resistors. So I need to address this anyways.

The attenuator should allow me to adjust the MV into an upper range that drives the 50W or so output, but at 12W out to the speaker. But I reckon that if I scale back the plate volts and rebias, at least there is less risk of smoking the tubes and possibly frying the OT.
  Reply With Quote
Old 18th April 2012, 07:52 PM   #27
shanx is offline shanx  Canada
diyAudio Member
 
Join Date: Dec 2010
Location: Quebec
I am certain there are a lot of variants to the simple power attenuation I suggest, but I figure it is worth a try to keep it simple and low cost.
  Reply With Quote
Old 20th April 2012, 04:27 PM   #28
shanx is offline shanx  Canada
diyAudio Member
 
Join Date: Dec 2010
Location: Quebec
Default Dropping V1b plate supply?

Could be done, or upping V1a supply to same as V1b.
Comments or experiences welcome. I just want to look at the effect on the headroom.
  Reply With Quote
Old 5th October 2012, 12:42 PM   #29
shanx is offline shanx  Canada
diyAudio Member
 
Join Date: Dec 2010
Location: Quebec
With a lot of other projects on the run, it has been a while since I posted on this ongoing rebuild.
There was a big renovation to do in my home workshop, still in finishing stage and as usual took way longer than planned. Did manage to steal some time to work on a pine cabinet converting this rather heavy combo unit to an amp head. I was going to mount the reverb tank in the head, but had the idea to leave it out for now. This frees up 2 more preamp tube sockets to play with!
Thanks Simon B and Razorrick, for encouraging me to explore some ''high gain'' options. I have the attenuator resistors now, so I need to get those wired up for some trials. More on that soon, I hope.
  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
Hello from mid west Ohio Mike Caldwell Introductions 2 22nd January 2012 04:49 AM
Hello from West Florida Parasonic Introductions 2 10th February 2010 07:50 PM
Mini Aleph rebuild jupiterjune Pass Labs 12 25th June 2007 05:11 PM
hello from west coast UAS guitarmaker Introductions 1 31st December 2004 01:17 PM
West Cobb, GA acweibel Multi-Way 5 3rd January 2004 10:52 PM


New To Site? Need Help?

All times are GMT. The time now is 12:41 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