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 2nd June 2010, 02:39 AM   #1
Bigun is offline Bigun  Canada
diyAudio Member
 
Bigun's Avatar
 
Join Date: Jan 2009
Blog Entries: 2
Default my CELLINI triode amp

I've been building SS amps for about a year [designing TGM3 - output Triples], but a friend of mine who is an ardent tube fan couldn't suffer my blundering about with transistors any longer. This past couple of weeks I've been receiving bits and pieces as a gift. A chasis, some glass bulb shaped objects, a couple of strange looking objects which I'm told are paper-in-oil capacitors made in Russia before I was born and some Hammond iron.

So now I will try to learn about tubes (or valves as they call them where I come from)

I'm seeking a bit of encouragement and advice from the Forum as I go.

The schematic for which these parts are for is based on an old design known as Lilliput so it may be familiar to some of you.
Attached Images
File Type: jpg Cellini_1v0.jpg (158.7 KB, 2381 views)
__________________
"The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed." Robert M Pirsig.
  Reply With Quote
Old 2nd June 2010, 02:20 PM   #2
diyAudio Member
 
kavermei's Avatar
 
Join Date: Jan 2005
Location: Lokeren, Belgium
Send a message via MSN to kavermei
Hi, welcome to tubes, I have some thoughts...

- 6as7 often has poorly matched sections, so it is not the best choice for an amp without feedback... Also there are tubes with nicer curves around (the 6as7 was never designed for audio use.) It does have great looks, though.

- This amp will not have very much gain. Depending on your source, you may need to use 6sl7 instead of 6sn7 to get sufficient drive to the output tube.

- You have almost no current margin on your 155C choke. I don't know how close it is specced so you'll probably get away with it, but it would be bad news if it went into saturation during signal peaks.

- Remove LED1 and LED2, they don't serve much purpose and they'll cause nasty switching noise.

Kenneth
__________________
Never send a human to do a machine's job. --Agent Smith
  Reply With Quote
Old 2nd June 2010, 02:32 PM   #3
Stixx is offline Stixx  Germany
I am
diyAudio Member
 
Stixx's Avatar
 
Join Date: Sep 2003
Location: Southern Germany
Quote:
6as7 often has poorly matched sections, so it is not the best choice for an amp without feedback... Also there are tubes with nicer curves around (the 6as7 was never designed for audio use.) It does have great looks, though.
True, still the original Lilliput was built many times and is still being sold as a kit in Italy (audiokit.it)... maybe for its looks ...

The original Lilliput also uses the 6922/ECC88 as input tube that has more gain.

While those ESE125 are quite inexpensive they don't offer much in the bass department which the 6AS7G are capable of, so I'd think about better OPT's (1.4K:6 ohm was the original from Megahertz).

Good luck!
  Reply With Quote
Old 2nd June 2010, 02:48 PM   #4
Cassiel is offline Cassiel  Libya
diyAudio Member
 
Cassiel's Avatar
 
Join Date: Sep 2004
Location: Madrid
Quote:
Originally Posted by kavermei View Post
Hi, welcome to tubes, I have some thoughts...

- 6as7 often has poorly matched sections, so it is not the best choice for an amp without feedback... Also there are tubes with nicer curves around (the 6as7 was never designed for audio use.) It does have great looks, though.


Kenneth
The looks is the only thing I like about the 6as7. Don't waste your time with that tube, el84 and 6v6 are much much better. I did build the Lilliput and I was never happy with it. Tube is cheap but the power supply and the OT makes it expensive. It needs big caps and a big OT. Hard to drive also, hum likely a problem... I hate that tube :-).

It might be OK in PP but not for a SE amp.
__________________
DIY Corporal
  Reply With Quote
Old 2nd June 2010, 03:54 PM   #5
Bigun is offline Bigun  Canada
diyAudio Member
 
Bigun's Avatar
 
Join Date: Jan 2009
Blog Entries: 2
Thanks guys, it's good to have company.

Well, the bits I have are provided as gifts from a friends junk box so it provides the easiest path for a first build - i.e. it's free. The looks might be important for the WAF yet...

How do you think I could build it / design it so that it would be relatively easy to upgrade the performance ? Would I be able to drop in a different tube and tweak the bias ?

The 155C, if I understand the concern correctly, it is that it's rated for 8mA and I'm already expecting a bias current of 6mA through it leaving only 1-2mA headroom for signal swings ? Doesn't C2 keep the signal out of the choke ?
__________________
"The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed." Robert M Pirsig.
  Reply With Quote
Old 2nd June 2010, 04:30 PM   #6
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
Welcome Bigun, and congratulations with widening of your horizon!

Try 6V6 or EL84, as suggested!

Also, a single EL82 (or Russian 6F3P) is a good start! It contains both preamp triode and an output pentode.
__________________
If I disappear suddenly, that means I finally created a time machine and pushed wrong button that brought me to Stalin's Russia. In any experiment any result is the result. Even if it is negative.
  Reply With Quote
Old 2nd June 2010, 05:00 PM   #7
Bigun is offline Bigun  Canada
diyAudio Member
 
Bigun's Avatar
 
Join Date: Jan 2009
Blog Entries: 2
Hi Wavebourn, thanks for welcoming on board !

Well, 6V6 and EL84 are Pentodes, which is different right ? It's like taking a BJT amp and changing to MOSFETs (for a SS guy).

Is it not possible to build this amplifier with Triodes ?
__________________
"The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed." Robert M Pirsig.
  Reply With Quote
Old 2nd June 2010, 05:11 PM   #8
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Blog Entries: 5
With those OPTs EL84 or 6V6 will make a better amp and a less problematic build... if you need some EL84 to push you over the edge, i could offer some for the cost of post.

dave
__________________
community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi
p10-hifi forum here at diyA
  Reply With Quote
Old 2nd June 2010, 05:45 PM   #9
Cassiel is offline Cassiel  Libya
diyAudio Member
 
Cassiel's Avatar
 
Join Date: Sep 2004
Location: Madrid
Quote:
Originally Posted by Bigun View Post
Hi Wavebourn, thanks for welcoming on board !

Well, 6V6 and EL84 are Pentodes, which is different right ? It's like taking a BJT amp and changing to MOSFETs (for a SS guy).

Is it not possible to build this amplifier with Triodes ?
To triode wire a pentode is easy, it only takes one 330 Ohms resistor from the plate to the screen. Planet 10 is right, less problematic and better sounding.
__________________
DIY Corporal
  Reply With Quote
Old 2nd June 2010, 06:45 PM   #10
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
Quote:
Originally Posted by Bigun View Post
Is it not possible to build this amplifier with Triodes ?
Nothing is more valuable than an experience!

You may use tubes you friend gave you then go forward and do something different to compare!
__________________
If I disappear suddenly, that means I finally created a time machine and pushed wrong button that brought me to Stalin's Russia. In any experiment any result is the result. Even if it is negative.
  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
Another 3f4 spice triode model: 5718 submini triode wa2ise Tubes / Valves 0 5th September 2008 04:31 AM
My EL84 Triode PP Amp sorenj07 Swap Meet 7 19th June 2008 04:13 PM
SE Triode amp for a newbie tta60 Tubes / Valves 24 15th May 2006 03:13 AM
Triode amp for sale. G Swap Meet 0 9th June 2004 10:45 PM
what is the simplest possible triode amp? cuallito Tubes / Valves 20 13th April 2004 01:17 AM


New To Site? Need Help?

All times are GMT. The time now is 06:15 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