The Hundred-Buck Amp Challenge - Page 159 - 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 20th February 2014, 02:35 AM   #1581
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
Looking for a bunch of EF86 tubes and 6CW4. ??

Thx-RNMarsh
  Reply With Quote
Old 21st February 2014, 01:17 AM   #1582
diyAudio Member
 
Join Date: Mar 2007
Location: Kansas
They're pretty readily available from most tube vendors. The EF86 in particular is a common tube in guitar amps and is currently produced by JJ and Electro-Harmonix, although opinions vary on their quality compared to NOS examples. The 6CW4 appears to be available from all the vendors I've checked for around $17
__________________
My band Waffle Stomp: http://www.facebook.com/wafflestompband
  Reply With Quote
Old 22nd February 2014, 08:59 AM   #1583
Account disabled at member's request
 
Join Date: Jan 2014
Location: I'm not here anymore !
Is that what those things are ? ! I have a lot of them but one is a shorty a 8B10 that I use as a paper weight on my table !
It has 4 sections that all test good ! . I always wondered what they were but I never remembered to ask anyone ! .

Last edited by Gary Vee; 22nd February 2014 at 09:04 AM.
  Reply With Quote
Old 14th June 2014, 06:03 PM   #1584
diyAudio Member
 
Join Date: Aug 2008
Quote:
Originally Posted by RNMarsh View Post
Looking for a bunch of EF86 tubes and 6CW4. ??

Thx-RNMarsh
Go for 6J32P (Soviet equivalent). Cheap and plentiful on ebay or other sites.
  Reply With Quote
Old 22nd June 2014, 11:51 AM   #1585
diyAudio Member
 
scott17's Avatar
 
Join Date: Aug 2009
Location: JFK
Default 6AF11 revisited

About 2 years ago, I put together a 6AF11 amp based on the Squirrel Monkey idea. I was able to stabilize it with no oscillation, and it sounded good.

I wanted to see if I could easily replicate the stable circuit to make sure it was not just the original layout or some other fluke that made it not oscillate. The answer is yes. No oscillation at any volume or settings. At about half volume, it is clean and chimey. Full on it has pretty good drive and nice distortion. In pentode it is around 1 watt based on rough measurements, just hitting a power chord and measuring the RMS volts on the speaker terminals.

Sounds surprisingly good for a $3 TV tube. The only tone control is a bright switch. Enabling the feedback calms the bite down a little bit.

The speaker is the Eminence 8" 820H Patriot. Nice sounding speaker for an 8".

Scott
Attached Images
File Type: jpg 6af11a.jpg (337.2 KB, 143 views)
File Type: jpg 6af11b.jpg (282.3 KB, 126 views)
File Type: jpg 6af11c.jpg (289.4 KB, 123 views)
File Type: jpg 6af11d.jpg (280.7 KB, 122 views)
File Type: jpg 6af11e.jpg (363.6 KB, 117 views)
File Type: jpg 6AF11guitaramp.jpg (126.2 KB, 65 views)
  Reply With Quote
Old 22nd June 2014, 03:40 PM   #1586
diyAudio Member
 
scott17's Avatar
 
Join Date: Aug 2009
Location: JFK
Yes, I did leave the coupling cap after the second stage off of the drawing.

Whoops.

Here is the correction.
Attached Images
File Type: jpg 6AF11guitaramp.jpg (127.9 KB, 65 views)
  Reply With Quote
Old 22nd June 2014, 08:56 PM   #1587
diyAudio Member
 
Join Date: May 2010
Location: Hawkes Bay
Nice circuit. Nice build. Did you use a star ground?
  Reply With Quote
Old 23rd June 2014, 12:44 AM   #1588
diyAudio Member
 
scott17's Avatar
 
Join Date: Aug 2009
Location: JFK
Thanks.

A hybrid star/buss ground. On the turret board there are 2 groups of ground points. I connected a solid copper bare 18AWG wire between the pentode & second stage cathode circuit grounds and the 1st stage cathode circuit ground. All other grounds: enclosure, power supply, volume control, input jack, OT secondary, and heater ground connect to this buss wire. The AC ground is a separate wire grounded to the enclosure right at the IEC power inlet.

Concerning the heater ground, I did not use the conventional artificial center tap method, I just grounded one side of the heater supply. It does make a difference in this case which side is grounded. One side gets rid of the hum, and the other side does not have as much of an effect.

Last edited by scott17; 23rd June 2014 at 12:47 AM.
  Reply With Quote
Old 23rd June 2014, 07:15 PM   #1589
diyAudio Member
 
scott17's Avatar
 
Join Date: Aug 2009
Location: JFK
Default Turret board layout

In case anyone is interested in putting one of these together, here is a layout for a 12 position turret or tag board.

Scott
Attached Images
File Type: jpg 6AF11taglayout.jpg (128.0 KB, 53 views)
  Reply With Quote
Old 11th July 2014, 01:11 AM   #1590
diyAudio Member
 
Join Date: May 2005
Location: Michigan
Speco T-7010 trivia.

I got some of these years ago before they were redesigned. I recently had access to a fancy RLC analyzer and took a bunch of measurements on one.

This may be useless info since you can't buy the old design, but hopefully somebody else has some hoarded away.

I converted an XLSX spreadsheet to PDF because I don't have any spreadsheet s/w on this PC, and it's viewable.

I hope it's mostly self-explanatory...I measured inductances for various windings at 1 kHz 1 Vrms, then 10 Vrms and multiple frequencies, leakage inductance for various measured and shorted windings, and whatever else seemed interesting at the time, before I lost my opportunity...visiting someone with work access to a lab...

All inductance measurements were 'dry' (no DC).

I hope this of interesting if not useful to somebody. I found it interesting to see how much primary inductance it had under different measurement conditions. 10 V was the maximum available so that's as high as the data went.

The lamination stack approximate measurements were made by offsetting the stamped steel frame thickness or double that as appropriate with a digital caliper. The cryptic EI lamination dimensions refer to the E and I lamination shapes, and the 'E c w' is E lam center leg width. 'E t/b w' is the width of the other two legs of the E shape lamination.

I didn't figure out the core area, but that's probably easy to figure out, despite being of little use in this case ;O).
Attached Files
File Type: pdf T7010.pdf (187.7 KB, 13 views)
__________________
Murray

Last edited by multi-volti; 11th July 2014 at 01:17 AM.
  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
Hafler Five Hundred problem hatrack71 Solid State 4 10th June 2009 12:38 PM
most bang-for-the-buck sub-amp skogs Solid State 12 8th September 2007 10:22 AM
Buck & boost transformer Ilianh Parts 1 15th March 2004 06:03 AM
a hundred questions from a noob zoobie Solid State 5 31st May 2003 02:04 PM
Nineteen Hundred Ninety Nine Posts And Counting ;-)... mrfeedback Everything Else 12 21st May 2003 05:59 PM


New To Site? Need Help?

All times are GMT. The time now is 10:16 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