Octal Hagerman Cornet Experiences - 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 18th October 2005, 03:20 AM   #1
fergs1 is offline fergs1  Australia
diyAudio Member
 
Join Date: Jan 2005
Location: melbourne
Default Octal Hagerman Cornet Experiences

Calling all octal cornet builders, an invitation to post piccies and share experiences building this phono stage especially the scratch builders as I am leaning towards this design to build. Other octal phono designs most welcome infact a definitive octal thread would be great.Lead on McDuff! cheers fergs
  Reply With Quote
Old 18th October 2005, 10:34 AM   #2
diyAudio Member
 
Join Date: Mar 2005
Location: Melbourne Again
I've been looking at building one of these also, with the added variable phono eq mod (I have 78's I want to play).

Do you have a reasonably priced local source for the transformer? The hammond stuff usually costs about twice the price of the US out here, I'm in Melbourne also.
  Reply With Quote
Old 18th October 2005, 12:15 PM   #3
fergs1 is offline fergs1  Australia
diyAudio Member
 
Join Date: Jan 2005
Location: melbourne
the only local source I know of is black art trans. keep an eye out on ebayau as lots of pt's and chokes apppear cheers chris
  Reply With Quote
Old 18th October 2005, 02:45 PM   #4
diyAudio Moderator Emeritus
 
Bas Horneman's Avatar
 
Join Date: Apr 2002
Location: The Netherlands
Blog Entries: 18
I reckon it would be worthwile for you guys to get a custom transformer wound. Since a phono stage can do with extra measures to keep noise out of your phono stage..Such as electrostatic screens between primary and secondary. And then go DC on the filaments with a seperate (maybe surplus) transformer.
  Reply With Quote
Old 18th October 2005, 06:23 PM   #5
diyAudio Member
 
Join Date: Jul 2004
Location: Illinois
I am in the planning stages of building one also. Actually a Claricorn ( Clarinet and Cornet 2 ) in the same chassis with one power supply for both. I am also leaning towards wiring PTP instead of using the boards and building the Cornet side as a hybrid, ( miniature/octal ). I'm trying to keep the costs low. I have the power transformer already and I think I can source the rest of the parts for around $150.00 without the tubes and chassis. I will make the chassis myself. I would be very interested in pics and comments from others that have gone this route also.
Mark
  Reply With Quote
Old 21st May 2011, 08:00 AM   #6
milosz is offline milosz  United States
diyAudio Member
 
Join Date: Oct 2006
Default Cornet2 - octal Cathode Follower

7025's and 6SN7

Click the image to open in full size.

Click the image to open in full size.

Copper Semi-octal Cornet2
  Reply With Quote
Old 23rd May 2011, 01:15 AM   #7
Richard is offline Richard  Australia
diyAudio Member
 
Join Date: Apr 2005
Location: Melbourne
Hi Guys,

You can try Voller transformers in Highett. Paul is great to work with and his transformers are reasonably priced. Turn around time is also quick. I got a surplus transformer from him for my cornet project, so also check if he has any lying around. There is also ses transformers in Dandenong:
http://www.southernelectronicservices.com.au/home.htm

In my cornet I have used a 12BH7 and 6n6p for the output tubes. I'll try the 6sn7 or even a pair 7193's at some stage. The 12BH7 is easy to implement since it's a noval and if you're using a ccs on the cathode it's easy to change the current set resistor and use a 12AU7 or 12BH7. The heater connection was different for the 6n6p and its use also resulted in a hum, so I went with the 12BH7.

What I'm doing now is building the power supply separate to circuit boards and adding in a choke.

Cheers,

Rich
__________________
"A little learning is a dangerous thing"

Last edited by Richard; 23rd May 2011 at 01:26 AM.
  Reply With Quote
Old 23rd May 2011, 01:44 AM   #8
djn is offline djn  United States
diyAudio Member
 
djn's Avatar
 
Join Date: Oct 2004
Location: Waterford Michigan
Here are pix of my Octal Cornet. I love it. I think it is the best phono pre I've had in my system and I tried a number of high end pres before I built this one.
Attached Images
File Type: jpg IMG_3140.JPG (674.9 KB, 287 views)
File Type: jpg IMG_3134.JPG (754.5 KB, 256 views)
File Type: jpg IMG_3142.JPG (147.8 KB, 239 views)
__________________
My "Art" website http://home.comcast.net/~djnagle/site/
  Reply With Quote
Old 23rd May 2011, 04:53 AM   #9
diyAudio Member
 
devilsindetails's Avatar
 
Join Date: May 2011
Location: 100th Meridian
Please excuse the intrusion. But I`m fascinated by this and the fact that at least one of these variations unashamedly uses the 7025 tube (which is a 12AX7 variant) and 6sn7.

I keep hearing the 7025 (12AX7) is such a poor tube for phono stage designs and yet here it is used again. I posited the use of 6sn7s as well in another thread and was met by deafening silence...so your opinions please regarding this topology.
__________________
"A problem left to itself dries up or goes rotten. But fertilize a problem with a solution--you'll hatch out dozens." (N.F.Simpson)
  Reply With Quote
Old 23rd May 2011, 07:16 AM   #10
milosz is offline milosz  United States
diyAudio Member
 
Join Date: Oct 2006
Default 7025

This is what Hagerman says about the Octal "hybrid" version of Cornet, hybrid in that it uses an octal 6SN7 cathode follower and 9-pin 12AX7's for gain:
I think the 6SN7 makes the best cathode follower. More current, better linearity, better voltage ratings. I like the tube. I also like the 12AX7 for high gain amplification.

Keep in mind, a LOT of the sound has to do with topology and circuit design, not just tubes. I can make no claim that octals are superior to novals, nor the other way around. Each tube has to stand on its own merits.
He's the engineer who's responsible for the design of this preamp - as well as several other very well-regarded designs- and if he says he likes using the 12AX7 in this design, I'll go with his expertise over opinions of people whose engineering pedigree is unknown to me.

The 7025 is a low noise / low microphonics version of the 12AX7. It is otherwise identical.
  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
WANTED: Hagerman Tech HAGUSB taloyd Swap Meet 0 30th October 2008 12:31 AM
Anyone Building A Hagerman Bugle? atw58 Analogue Source 5 14th April 2008 01:50 AM
Seduction or Cornet for phono??? cbutterworth Tubes / Valves 13 14th June 2007 09:52 AM
Octal Cornet RogueAngel Tubes / Valves 2 19th September 2003 01:23 AM
Hagerman's Vbe Multiplier pmkap Solid State 3 11th February 2002 12:32 AM


New To Site? Need Help?

All times are GMT. The time now is 04:43 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