sowter 9050 or Lundahl LL1660 line out transformer? - 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 11th September 2002, 04:33 PM   #1
diyAudio Member
 
Join Date: Jul 2002
Location: usa
Default sowter 9050 or Lundahl LL1660 line out transformer?

Hi, I'm having a hard time deciding which is better. The LL1660 by Lundahl or the Sowter 9050. I am using it for a 6sn7 balanced (push-pull) line out. Will try parafeed or dc coupled.

I've heard about people using torroid (power) transformers as a parafeed tranny. Does anyone have any experience with this technique? Does it SOUND good? Could it sound as good as a Sowter or Lundahl?

Thanks for any info!!!!

- Matt
  Reply With Quote
Old 14th September 2002, 03:33 AM   #2
dice45 is offline dice45  Germany
diyAudio Member
 
Join Date: Jan 2002
Location: Munich, Bavaria
Matt,

Sowter 9050 or LL1660PP: It depends what you want to achieve.

For the 6SN7 (R_p= 7k) the Sowter 8650 or 9050 certainly is better suited as the tube should face a load of atleast 15k.

With the 8650 you get 185R (+ secondary DCR) as output resistance, with the 9050 417R plus sec.DCR.

I am not sure if the 6SN7 is the right choice if you want to use the LL1660; it only has a stepdown turns ratio of 2.25 in PP to line out mode. You end up at about 3k output resistance then. Better use a 5687 or a juicy 12B4A to drive the LL1660.

Sonics: i haven't heard either in my system, but i heard the LL1660 in Thomas Mayers system and liked it very much; Thomas even recommended the thing for single-ended mode.

Sowter makes any custom job you want, Lundahl does not. But in general the sonic reputation of Lundahl is considerably better (exceptions exist).

I have decided to use the LL1660 PP for my preamp project; i will use a 12B4 to drive it and i guess the Lundahl driven by the right tube will be dramatically better than the Sowter. Moreover, it has way higher safety margins concerning isolation voltages. The only Sowter i considered was the 9111 but this baby has to be used in parafeed mode which i want to avoid: parafeed needs a cap to block the CD; this is a coupling cap. I strive to avoid coupling caps in my system.
__________________
Greets,
Bernhard
  Reply With Quote
Old 28th September 2002, 06:22 PM   #3
diyAudio Member
 
Join Date: Jul 2002
Location: usa
Default 6H30pi for LL1660pp?

OK, thanks for the info. I have decided to go with the LL1660PP and got 4 of them! Hopefully I do this right and don't waste any money in the process.

Now, I'm just trying to figure out which output tubes to use with this transformer. I want to use dual triodes. Originally like I said, I wanted to use 6sN7gt's, but not sure about that now after reading your response.

What does anyone know about the Sovtek 6H30pi? Is this a good tube to use as a push-pull with the LL1600PP? I was thinking the 12b4 but it's a single section, and i'm hoping to get away from having too many tubes on my 4 channel preamp (mic and line/instrument).

I guess what I'm asking is can some of you give me the names of tubes that would work well with a LL1660PP besides the 12b4?

Also, a more general question...

If your grid voltage is -10 volts with respect to the cathode, does that mean that you can't have an input siganl greater than 10 volts? The preamp that will be driving the output stage will have sometimes a voltage of 30-40 volts ac, so just wondering if i need that kind of bias?

thanks a lot for any help!

- matt mitchell
  Reply With Quote
Old 28th September 2002, 07:20 PM   #4
dice45 is offline dice45  Germany
diyAudio Member
 
Join Date: Jan 2002
Location: Munich, Bavaria
Matt,

no knowledge of the 6H30.

It is an advantage to have a singel section tube: for PP use you can match the tubes, with a dual-system envelope you have to like with what you got. Or seek for internally matched ones, have fun!
Better go fot he 12B4.

Bias: if bias is -10V, then indeed you are well advised to keep your input signal below a peak voltage of 10V (p2p of 20 Volt). Make that 9V/p2p 18V, as the tube starts to pull grid current between 0 and -1 V at the grid. One exception: the driving stage is designed to deliver enough current to drive the grid..
__________________
Greets,
Bernhard
  Reply With Quote
Old 28th September 2002, 07:34 PM   #5
diyAudio Senior Member
 
fdegrove's Avatar
 
Join Date: Aug 2002
Location: Belgium
Default PARALLELED TUBES?

Guys,

I know I keep on bugging you.
For the record and once and for all,please anyone wants to have a stab at what exactly a paralleled dual triode amounts to?
Before you pass on judgement please??

Cheers,
__________________
Frank
  Reply With Quote
Old 28th September 2002, 07:58 PM   #6
diyAudio Member
 
Brett's Avatar
 
Join Date: Jan 2002
Matt,

The 6H30 will be fine in your pre, PP driving an LL1660. Set the Vp to 200V (B+ ~210V), Ia to 20mA/triode and Vg will be about -7.5V. I would put a constant current sink in the tail of each triode pair to ensure that the two tubes remain as close to each other in performance as possible. Whilst the LL1660PP has a small gap to allow for imbalances betwen the tube pairs, if you exceed what the gap allows, the performance of the transformer will degrade significantly.

Other options would be the ECC99 or 6N1P, but both have more gain and a higher Rp, and Zout. Use the 6H30, nice tube, tough as nails, and <b>very</b> linear.

<b>If your grid voltage is -10 volts with respect to the cathode, does that mean that you can't have an input siganl greater than 10 volts? The preamp that will be driving the output stage will have sometimes a voltage of 30-40 volts ac, so just wondering if i need that kind of bias?</b>
Why are you building another stage with a gain of around 15, when you already have 30Vac+? All you'll be doing is attenuating the signal down to get the next stage not to clip. Too much gain means noise and headroom problems. What you want is just enough gain, and lots of headroom. You're bass ackwards here.

To answer the question, with a Vg of -10V, if you apply a signal to the grid that is greater than 10V, you'll cause the grid to go positive, grid current to flow, and the stage to "clip" and distort radically. You can't just up the bias on a stage (that much), because all the tube's parameters and external loads are interdependent, and doing so might cause lots of distortion or the tube to switch off.

Cheers
  Reply With Quote
Old 28th September 2002, 08:06 PM   #7
diyAudio Senior Member
 
fdegrove's Avatar
 
Join Date: Aug 2002
Location: Belgium
Default 12B4

Folks,

Other than the fact that I'm happy to see the 12B4 is still around. In the long run I'd certainly opt for a currently manufactured tube.
Nobody can predict pricing on either one of them but logic tells me the latter stand a better chance for maintaining prices in the long run.

Rgds,
__________________
Frank
  Reply With Quote
Old 28th September 2002, 10:51 PM   #8
diyAudio Member
 
Join Date: Jul 2002
Location: usa
OK, thanks everyone for your very valuable help.

I'm wondering about the gain issue. If a tube has a mu of 15, BUT going into a step-down transformer, what REALLY is the gain of the tube (plus the transformer)? I mean, if my desired output impedance is to be somwhere around 600 or less, what kind of ac voltage do I really need? what if i want it to interface with +4dB inputs? what voltage would i need to be outputing?

a million thanks again to you all!

matt
  Reply With Quote
Old 30th March 2003, 05:35 PM   #9
Account Disabled
 
Join Date: Nov 2002
Location: hong kong
I test them all already.

In my favourite i like Tango NP-216.

thanks

Thomas
Attached Images
File Type: jpg 2003-02-03 meeting 015.jpg (73.7 KB, 1156 views)
  Reply With Quote
Old 18th March 2010, 11:34 PM   #10
diyAudio Member
 
Join Date: Sep 2005
Hello

The LL1660S can be used in line stage to drive balanced power amp a la AlephX or Aleph2.
If yes I would like to try it out with WE407A tubes .
Using these tube the gain will be OK to drive my AlephX or Aleph2 ?
Any advise , idea welcome !
Thanks you guys
Greets
  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
GB: Sowter 10K:10K Input Transformer luvdunhill Group Buys 161 1st July 2013 12:07 AM
Sowter's Radford transformer theoldtrout Tubes / Valves 0 28th September 2008 11:45 PM
Iron: Sowter, Lundahl, Magnequest tubesguy Swap Meet 5 7th June 2008 08:54 AM
Problems Lundahl LL1660 and 6c45 to 6c33 Triode!Need help! barossi Tubes / Valves 6 29th October 2003 10:08 PM
Raven using Lundahl instead Sowter Maurizio Tubes / Valves 2 17th September 2003 04:11 PM


New To Site? Need Help?

All times are GMT. The time now is 03:30 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