What preamp should I build? - Page 4 - 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 10th January 2008, 01:44 PM   #31
arnoldc is offline arnoldc  Philippines
diyAudio Member
 
Join Date: Apr 2003
Location: Makati
Send a message via Yahoo to arnoldc
andy, I have 8 pairs of 10Y and I've been, in my mind, trying to make one. Since I saw the Electronluv, I always wanted to make one, then the 26 came along.

That's just the kick in the **** I needed! I will make a 10Y pre now! My friend is the distributor of Lundahl here and he's got lots of 1660.

Thanks for sharing that information on the op points! Can you complete the recipe by sharing the wiring of the 1660? ALT-S perhaps?

I would agree that there's nothing wrong with a 6SN7 pre, but for me, compared to my 26... ahh no contest.
  Reply With Quote
Old 10th January 2008, 01:53 PM   #32
diyAudio Member
 
Join Date: Sep 2003
Location: London
http://www.lundahl.se/pdfs/datash/1660.pdf

Wiring is indeed ALT-S as you say. I was astonished that the 10Y worked so well at such a low current, but this does enable you to use the 5mA SE version which means more inductance. With a plate resistance of 5k the 10Y probably likes to see this higher inductance. I haven't tried the 10mA version - that should work too.

I made a circuit diagram but don't know how to post it - also it's in .bmp right now. I'm not a wizard with computing. Andy
  Reply With Quote
Old 10th January 2008, 02:02 PM   #33
arnoldc is offline arnoldc  Philippines
diyAudio Member
 
Join Date: Apr 2003
Location: Makati
Send a message via Yahoo to arnoldc
hi andy, open it up in microsoft paint, then save as .gif and if it's less than 100K, you can attach it to your post.

otherwise, and if you don't mind, you can send it to my email and i can post for you.
  Reply With Quote
Old 10th January 2008, 03:22 PM   #34
diyAudio Member
 
Join Date: Oct 2004
Location: Maui, Hawai'i, USA
Mike, I have that transformer in service in the dozens, have never encountered a failure.  Buck and boost windings are a grand tradition among small builders who can't finance specialty transformers;  the only thing unusual here is the use of one primary as a secondary.  A winding doesn't know if it's a primary or secondary, it's just a winding, on the core with all the other windings.  Of course, using one half the primary effectively halves the VA of the transformer, which is why I use a 20VA part for a 6 watt application.  For EU clients, I use the Hammond 182E117;  use it if you're nervous.  You'll want to drop the cathode resistors a value (to 75 and 68Ω ) to keep the current up.  All it costs is about 16 volts on the B+;  the circuit still has plenty of input and output swing.

I built both the Aikido and Bruce's grounded grid (which is actually a singly-driven diff-amp, a circuit of which I'm very fond), and honestly preferred this one; it's quieter and has higher rez. Of course, I would say that, hm?

  :^)

Poinz
  Reply With Quote
Old 10th January 2008, 06:39 PM   #35
diyAudio Member
 
Brett's Avatar
 
Join Date: Jan 2002
Quote:
Originally posted by OzMikeH
Power supply complexity: It needs to be very, very clean because of poor PSRR. Lots of filtering at a couple of hundred volts can't be cheap.

Perhaps the people who wrote about their build of it went overboard with the power supply.

Performance is important, Particularly low noise and high detail.
If performance isn't excellent then I may as well spend a few hundred bucks on super-duper op-amps. I'd rather not go down that path though.
The PSRR of the 12B4 is no different to the 6SN7 or the 26 or any other triode. It's not hard, nor is it that expensive. If you can deal with the extra gain use a CCS load and/or a Maida reg. CCS and shunt reg is best, but that is more complex.

I didn't read much of the linked 12B4 thread as there were a bajillion posts for something that is incredibly simple.
  Reply With Quote
Old 10th January 2008, 09:42 PM   #36
diyAudio Member
 
Join Date: Nov 2002
andyjevans,

I would love to have a quiet 26 line stage. To be perfectly honest here I simply cannot build a quiet one. I would pay to have one built.
  Reply With Quote
Old 10th January 2008, 11:16 PM   #37
arnoldc is offline arnoldc  Philippines
diyAudio Member
 
Join Date: Apr 2003
Location: Makati
Send a message via Yahoo to arnoldc
burnedfingers, hook up with kevin kennedy
  Reply With Quote
Old 11th January 2008, 12:07 AM   #38
arnoldc is offline arnoldc  Philippines
diyAudio Member
 
Join Date: Apr 2003
Location: Makati
Send a message via Yahoo to arnoldc
I'm posting this on behalf of andyjevans

Click the image to open in full size.

Geez, I'm tempted to use my VR105 on the plate
  Reply With Quote
Old 11th January 2008, 12:21 AM   #39
diyAudio Member
 
Join Date: Sep 2003
Location: London
Thanks for posting that!

I should point out that the 107v B+ just happened to be from a transformer I had handy - I used this voltage for testing a whole heap of DHTs, some of which were 90v max plate voltage.

For the 10Y you could take up the voltage over 300vDC. The current stayed low because of the LL1660/5mA which I happened to have. Again, you could swap that for a LL1660/10mA for instance.

The schematic isn't optimised - it just works and sounds very nice indeed.
  Reply With Quote
Old 11th January 2008, 12:26 AM   #40
OzMikeH is offline OzMikeH  Australia
diyAudio Member
 
Join Date: Mar 2007
Excellent guys, I'll start collecting and building some external power supplies. Meanwhile I'll ponder some more. Had another look at the Tek 845b, Seems a shame to trash it but there's a million of them out there and mine has had mice living in it. SHould be able to run all sorts of stuff off such a big supply.

Just spotted that Heretical line stage this morning. Steep learning curve at the moment. This High voltage low current thing is still too new to me to be a seat of the pants thing.
I appreciate the advice and tolerance of stupid questions.

Poindexter, I'll definitely remember the trick with the double primaries.
__________________
Help some guys with funny hair bang two rocks together really hard.
http://athome.web.cern.ch/athome/LHCathome/whatis.html
  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
Need to build JC 2 preamp HKC Solid State 459 14th July 2014 08:00 AM
BDT Preamp build jkeny Tubes / Valves 13 5th November 2008 12:37 AM
Build Preamp Jpoole908 Solid State 1 8th June 2008 12:47 AM


New To Site? Need Help?

All times are GMT. The time now is 09:11 PM.


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