tubelab simple se: increasing the drive - 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 1st December 2009, 03:42 AM   #1
diyAudio Member
 
Join Date: Aug 2008
Default tubelab simple se: increasing the drive

When I have the simple se hooked up to a tube preamp it is giving full output with the volume control at about the 12:00 position.
When I have (the other) simple se hooked up that has its own volume control driven by a cd player the volume control is all the way up, and possibly not quite as full volume as when driven by the preamp. Even less loud when drivin by a mp3 player.
Also, not sure but the power transformer is warmer (still not "hot").
My questions are:
Does the amp (power and output transformers) work harder to make music of a certain loudness when not using a pre amp ( or using a unity gain preamp)?

Is it possible to switch the 12AT7 tube for a slightly higher gain tube (12 AX7 or 5751) for higher gain if not using a pre amp?
Thanks,
Paul
  Reply With Quote
Old 1st December 2009, 04:18 AM   #2
Cassiel is offline Cassiel  Libya
diyAudio Member
 
Cassiel's Avatar
 
Join Date: Sep 2004
Location: Madrid
To the first question: LOL
To the second: yes, if cd output not enough to get max watts a switch to 12ax7 would help.
  Reply With Quote
Old 1st December 2009, 04:41 AM   #3
Cassiel is offline Cassiel  Libya
diyAudio Member
 
Cassiel's Avatar
 
Join Date: Sep 2004
Location: Madrid
On a second thought I think something is wrong somewhere. If I'm not mistaken the amp's sensivity is pretty good, almost the full mu of the driver tube (CSS). What's your output tube ?
  Reply With Quote
Old 1st December 2009, 05:23 AM   #4
rknize is offline rknize  United States
diyAudio Member
 
rknize's Avatar
 
Join Date: Feb 2009
Location: Chicagoland
Send a message via AIM to rknize Send a message via Yahoo to rknize
I am scratching my head here, but I think you are comparing apples to oranges. The SSE has a lot of gain...plenty to drive to output stage well into clipping using "line level" inputs. What size pot are you using the SSE #2? I suspect that either it is not hooked-up right (wiper should be on the amp side) or the portable player doesn't have enough drive to get past the lowered input impedance from volume control.

Are you asking why the two SSEs seem to have different gain or why the CD player can't drive the amp? What happens if you connect the CD player to the amp with no volume control?
  Reply With Quote
Old 1st December 2009, 01:39 PM   #5
diyAudio Member
 
Join Date: Aug 2008
The simple se I made with a volume control is for my brother. He plays his music pretty loud. So I am using KT88's and 6550's. I'm using a JJ (Tesla) 12at7.
Pretty sure it's wired correctly. It is a 50 Kohm pot.
It plays quite loud. I can easily hit 105 dB peaks on Open Baffle (audio nirvana) with MJK's H frame 18" woofer
( with B&K plate amplifier below 160 Hz).
It's just that with the vol pot all the way up, it's possibly not quite as loud, as with a pre amp ( with vol control half way up-- any higher and distortion is quite apparent).
Not a big deal, as it does sound great, and does play quite loud. I don't usually listen to music that loud, but my brother does. If so, is he completely out of headroom, where as if using a preamp, or different input tube, would the headroom (when playing loud!!) be better?
Thanks,
Paul
  Reply With Quote
Old 1st December 2009, 01:42 PM   #6
diyAudio Member
 
Join Date: Aug 2008
cd player doesn't have a vol control, so I can't connect it to the amp that doesn't have a vol control
Thanks,
Paul
  Reply With Quote
Old 1st December 2009, 03:55 PM   #7
rknize is offline rknize  United States
diyAudio Member
 
rknize's Avatar
 
Join Date: Feb 2009
Location: Chicagoland
Send a message via AIM to rknize Send a message via Yahoo to rknize
It sounds to me like your portable CD player does not have enough drive and/or enough gain, but you could confirm this by hooking the 2nd amp up to your preamp. If it works fine, then you know. What sort of CD player is this? Like a Discman or something?

I've been running my SSE directly off of my SqueezeBox for several months now while I renovate my basement. About 80% volume puts the amp into the onset of clipping. At 90% the clipping is noticeable.

Are you running the output stage in triode or UL? With or without CFB? If you run UL with no CFB, you will end up with more overall gain.
  Reply With Quote
Old 1st December 2009, 04:11 PM   #8
DougL is offline DougL  United States
diyAudio Member
 
Join Date: Feb 2004
Location: Wheaton IL.
Blog Entries: 30
Quote:
Originally Posted by pforeman View Post
Not a big deal, as it does sound great, and does play quite loud. I don't usually listen to music that loud, but my brother does. If so, is he completely out of headroom, where as if using a preamp, or different input tube, would the headroom (when playing loud!!) be better?
Thanks,
Paul
If your brother wants more voltage gain for his system, it is better to add a (tube) preamp. I would look at CCDA from John Broskie's Guide to Tube Circuit Analysis & Design.

Changing the input tube on a Simple SE will probably have major sonic impact.
Off the top of my head, here are some of the challenges.
A 12AX7 can only have a couple of mA of current. This is probably not enough to drive a 6550 miller capacitance, thus rolling off the high frequencies to one extent or another. Adding a source follower to compensate is possible, but may require an extra power supply.

Point is, this is more than a tube swap. its a partial redesign. George could tell you more, but that's my best guess.

HTH

Doug
__________________
Scienta sine ars nihil est - Science without Art is nothing. (Implies the converse as well)
Mater tua criceta fuit, et pater tuo redoluit bacarum sambucus
  Reply With Quote
Old 1st December 2009, 08:20 PM   #9
tomchr is online now tomchr  United States
diyAudio Member
 
tomchr's Avatar
 
Join Date: Feb 2009
Location: Greater Seattle Area
Are you sure the preamp has unity gain with the volume control past 12 o'clock?

If the max gain of the preamp is indeed unity gain, it sounds like the volume pot of the SimpleSE either isn't wired correctly or is loading the source too hard. The resistance of the volume pot should be on the order of 22~100 kOhm.

~Tom
  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
Tubelab Simple P-P booangler Tubelab 607 11th November 2014 09:24 PM
Electrolyticless Tubelab Simple SE nic6paul Tubelab 26 20th August 2013 01:56 PM
Tubelab Simple SE v.2 nic6paul Tubes / Valves 3 1st November 2009 01:59 PM
Tubelab SE with a 6BX7 to drive 845s rknize Tubes / Valves 0 3rd March 2009 10:02 PM
New SET: JE labs simple 45 or tubelab SE? cwujek Tubes / Valves 14 27th November 2007 05:15 AM


New To Site? Need Help?

All times are GMT. The time now is 06:04 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