#26 pre amp - Page 46 - 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 6th June 2010, 08:54 PM   #451
diyAudio Member
 
Join Date: Sep 2003
Location: London
Latest thoughts -

One thing I did over the weekend is change my 26 preamp from choke load to Hammond 126C output transformers. Very clear and detailed sound. Quite a forward sound. I don't have the best speakers connected right now, so hard to be more precise.

I got the 180v for the anodes from VR105 and VR75 glow tubes. I'm running at 6.3mA with 12.5v on the 1.9K cathode resistor (bypassed with 47uF). That's right on max, but it does give me the lowest anode resistance. May review this and bump up the cathode resistor value up to nearer 2.4K.

Just turned it on, so probably needs to settle in a bit. Any comments welcome!

Andy
  Reply With Quote
Old 7th June 2010, 02:53 AM   #452
Richard is offline Richard  Australia
diyAudio Member
 
Join Date: Apr 2005
Location: Melbourne
Hi Andy,

What is the bass like? The inductance has dropped to about 106 Henry, maybe more since you are only running 6.3mA out of the max 15mA.

How does it compare to the Lundahl?

I have some Silk interstage XF's but they're on 5K, the 10K L941S may be an another option. Also you may have more gain when compared to 15K - 20K line output transformers.

Rich
__________________
"A little learning is a dangerous thing"
  Reply With Quote
Old 7th June 2010, 06:31 AM   #453
diyAudio Member
 
Join Date: Sep 2003
Location: London
I only have some 6 inch wimpy full range speakers - not even that because they're not really full range - so I can't do much critical listening. But it seems to me that the bass is there. I think it's a good sound and well worth trying, since the 126C is fairly cheap and available. A friend who uses it measured it and said that the treble response is very good, though 15ma is the limit you should go to. He was using 10mA.

With this output transformer in place, it begs the question of whether I should change to a 10Y. I'm even wondering about a 46. Anyone used a 46 as a preamp? It's a great driver.

Andy
  Reply With Quote
Old 7th June 2010, 12:41 PM   #454
Richard is offline Richard  Australia
diyAudio Member
 
Join Date: Apr 2005
Location: Melbourne
Quote:
it begs the question of whether I should change to a 10Y
just do it man!

Then you can tell us how much better the Hammond is compared to the Lundahl in your 10Y linestage and we can do a Hammond 126C group buy ;-)

Quote:
I'm even wondering about a 46. Anyone used a 46 as a preamp?
I have a few sitting around and was thinking about using one in a dac output for a while, could use my 5K interstage as an output XF. I recall someone using a 2A3 in a similar role somewhere and our brother in arms, Mr Lampizator has recently used a 300B.

DAC300B

Rich out
__________________
"A little learning is a dangerous thing"
  Reply With Quote
Old 9th June 2010, 07:57 PM   #455
diyAudio Member
 
Join Date: Sep 2003
Location: London
Ok guys. Let's hear it for the 46!

I knocked up a board to plug in 5 pin tubes to my 26 preamp, with the 126C Hammond outputs.

Sound is extremely neutral. Well everyone says that about the 46. Bass is solid and good. It's very quiet. Plenty of detail. So far so good, and indeed it is good.

Compared with the 26 I just miss that frisson - the added vividness, life and zing. It's not that the 46 is flat - it's just neutral and bo doubt that should be good. I just miss the 26.

I tried the ST version of the 46 - NOS Tungsols. Nothing wrong there. Didn't try the Globe. May try that later when the ST sound has sunk in more.

Andy.
  Reply With Quote
Old 9th June 2010, 08:16 PM   #456
eboz is offline eboz  United States
diyAudio Member
 
Join Date: Mar 2006
Location: Boise, ID
Send a message via Yahoo to eboz
So suddenly on page 46 of this thread, it's transformed into a thread on type 46 preamp! Heh... I mostly hear of the 46 replacing the 45 with a few minor adjustments. I have all of the above tubes in-hand, but too many other projects stacked up at the moment to get to these tubes. I rather like to skip the preamp (at least as a stand-along component) and simply use DAC's output and the main amp's input stage as pre-amplification.

One thought I have is grounding the grid of the 26 and finding as low gain JFET as I can to place under the cathode. It's still too much gain, but could try dividing the input voltage. The 26 by itself is too low to fully drive a medium size tube such as 2a3 or 45 into clipping.
  Reply With Quote
Old 9th June 2010, 08:52 PM   #457
diyAudio Member
 
Join Date: Sep 2003
Location: London
I think the "preamp" is a bit of a virtual concept. What we simply have is stages of amplification, wherever they are physically situated. The total of what's in those stages, however many there are, is the amplification chain. A lot of tubes can be moved around in this chain, two of the most obvious being the 46 and 10Y - fine anywhere from input to output.

I tried the globe 46. More delicate treble, bass not so solid. Swings and roundabouts. the globe is really nice looking though!

If I have the energy I'll go on and try the 49 and maybe the 24a. I previously did a whole shootout of 4 pin DHTs and the ones I liked best were 26, 10y and 01A. The last two thoriated which may make a difference.

andy
  Reply With Quote
Old 9th June 2010, 10:10 PM   #458
diyAudio Member
 
Join Date: Sep 2003
Location: London
OK, now for the 49, now we're tube rolling.

Now this one is very good. Nice tone, delicate and detailed treble. Nice life to the sound and very clean. I like this a lot. It's struggling into a 126C since that's rated at 10K (106 henries) and the plate resistance of the 49 is around 11K. Not a match but still sounding nice, though bass is light.

I'm going to leave this one in for a while. I must admit the 46 came out after a couple of CDs - got a bit bored with the sound. This 49 has me a bit intrigued. Would probably sound good into a LL1660. It sounds quite like a 01A, and is of course much cheaper.

Andy
  Reply With Quote
Old 9th June 2010, 10:14 PM   #459
diyAudio Member
 
nicoch58's Avatar
 
Join Date: Oct 2004
Thanks Andy great to know .....
__________________
Sic58
  Reply With Quote
Old 9th June 2010, 10:20 PM   #460
diyAudio Member
 
Join Date: Sep 2003
Location: London
Quick correction - the plate resistance of the 49 is around 4K. That should be a better match for the 126C. The bass is still light, though. I don't think the 49 has quite the magic of the 26 but it's a contender.

Andy
  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



New To Site? Need Help?

All times are GMT. The time now is 07:22 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