Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Ideas for a low power amp that is bigger than a flea amp. 5-10W out?
Ideas for a low power amp that is bigger than a flea amp. 5-10W out?
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 25th June 2019, 04:25 PM   #1
kodabmx is offline kodabmx  Canada
Affordable triode connected sweep tube amps.
diyAudio Member
 
Join Date: Oct 2011
Location: Toronto
Ideas for a low power amp that is bigger than a flea amp. 5-10W out?
Default Ideas for a low power amp that is bigger than a flea amp. 5-10W out?

Hey everyone.

Since it's summer but I love my tubes, I want to build a low power amp (under 100W from the wall).

Criteria:

B+ 300V or so.
Triode connection preferred.
RLa-a 3k or 12k (what I have available)

Right now I'm thinking my 6F12P VA/PI concertina driving 6P43P in triode connection, fixed bias or "automatic" fixed bias using a board from audioamp.eu or Tent. Distortion isn't as important as waste heat in this one since the A/C is running anyway.

Does anymore have the parameters for a 6P43P in triode? Like the mu, gm, rp etc?

I usually run them hot but I'm thinking closer to class B on this one, like an idle around 10-20mA?

I also have 6P18P, 6F3P, 6P15P, 6P1P, but I'm thinking for triode mode, the 6P43P kills all of those options.

What do you think?

FWIW: My monoblocs raise the temperature of this apartment about 2 degrees C per hour until the room temp is over 30C unless I install the 12000 BTU unit along with the 5000 BTU (the apartment is only 380 sq ft!) but that raises the room noise to over 70db! Hence the reason for trying for a low powered design. Trying to build this without spending a cent, too.

Last edited by kodabmx; 25th June 2019 at 04:28 PM.
  Reply With Quote
Old 25th June 2019, 06:09 PM   #2
Lingwendil is offline Lingwendil  United States
diyAudio Member
 
Lingwendil's Avatar
 
Join Date: Apr 2008
Location: Oakley California
Well, since I'm doing similar currently as a test build for my "Spider" PCBs, best material I can find for triode mode 6P43P-E-

Tube Tester Files - EL82, EL84, EL86 Soviet Clones

http://www.tubesoundelectronics.de/b.../6p43ptwax.jpg

http://tec.org.ru/_bd/17/1764_643-.pdf

https://www.diyaudio.com/forums/atta...3p-ug2-150-pdf

https://www.diyaudio.com/forums/atta...3p-ug2-180-pdf

I've attached a scanned Russian datasheet, only two pages total . Maybe Anatoliy (Wavebourne) can help?

Triode mu looks to be around ~7, gm ~7.5mA/V, plate looks to be ~1K to 1.2K depending on application, at least in lower voltage applications. Higher voltage info seems hard to find. It does look like a very lovely tube, even as a driver really. Low triode mu appears to suggest that input capacitance wont be all that bad...

I plan to run ~310 volts supply, 6N2P concertina/volt amp, and garter bias. I'm pretty conservative with bias usually, so 250 volts A-K, 35mA, ~28 volts G1 (820R garter cathode resistors) and a pair of junkbox "30 watt" 6k:8 (or 3k:4) that I think are surplus guitar amp transformers- they'll do 40hz clean no problem down to somewhere around 20 watts, so I figure they would do for either an 8 or 4 ohm speaker in my project. Most of my speakers are 8 ohms, but I plan to build more 4 ohm setups at some point.
Attached Images
File Type: jpg 6p43p_e_pasp (1)-1.jpg (228.3 KB, 645 views)
File Type: jpg 6p43p_e_pasp (1)-2.jpg (211.9 KB, 646 views)
File Type: gif 6p43p-e_triode_curves_0.gif (20.3 KB, 624 views)
Attached Files
File Type: pdf 6n43n-E.pdf (53.4 KB, 22 views)
__________________
Check out My 6SN7 Push-pull Flea Amplifier project! PCB COMING SOON!

Last edited by Lingwendil; 25th June 2019 at 06:18 PM.
  Reply With Quote
Old 25th June 2019, 06:25 PM   #3
Lingwendil is offline Lingwendil  United States
diyAudio Member
 
Lingwendil's Avatar
 
Join Date: Apr 2008
Location: Oakley California
Ah, here we go. Managed to translate one of those, it aint' perfect but it seems useful...

Supposedly it's a 5000 hour tube
Attached Files
File Type: pdf 1764_643-.ru.en.pdf (360.9 KB, 55 views)
__________________
Check out My 6SN7 Push-pull Flea Amplifier project! PCB COMING SOON!

Last edited by Lingwendil; 25th June 2019 at 06:28 PM.
  Reply With Quote
Old 25th June 2019, 06:34 PM   #4
kodabmx is offline kodabmx  Canada
Affordable triode connected sweep tube amps.
diyAudio Member
 
Join Date: Oct 2011
Location: Toronto
Ideas for a low power amp that is bigger than a flea amp. 5-10W out?
Thanks for the info.

I'm thinking I'll run 2 VPT12-4170 transformers in series for OPTs. It works well enough on the monoblocs (full power at 30Hz). 3k seems good for 6P43P in triode mode. I'm going to use a bias board so it'll be easy to test the amp at different bias points anyway. Turn one pot, change all four tubes at once, right?

I'll start with 300V (or whatever the power supply makes) at 10mA and go from there... If I can make this amp basically benign as far as heat load, I'm good. The VA/PI has a lot of gain, and the OPTs can stand a bunch of gNFB before they act up, so maybe it won't be that bad?
  Reply With Quote
Old 25th June 2019, 06:35 PM   #5
kodabmx is offline kodabmx  Canada
Affordable triode connected sweep tube amps.
diyAudio Member
 
Join Date: Oct 2011
Location: Toronto
Ideas for a low power amp that is bigger than a flea amp. 5-10W out?
Marde! I just saw that in order to use these in triode at 10mA, you need -60V bias! The driver can swing it, but damn!
  Reply With Quote
Old 25th June 2019, 07:11 PM   #6
Lingwendil is offline Lingwendil  United States
diyAudio Member
 
Lingwendil's Avatar
 
Join Date: Apr 2008
Location: Oakley California
Yeah, they are thirsty pups, and need a good stranglehold to keep it to a trickle

Maybe a differential driver, negative rail for a CCS, and like 200~250 volt supply with garter bias? It'll eat up a bit of voltage making the negative bias more reasonable, and the garter bias scheme will only cost a couple watts in heat...

Maybe go for a 6P1P AB2 build, with a low idle current and fixed bias? Might be easier but transformers are harder to kludge from toroids in that situation. You'll use less heater power overall, which helps.
__________________
Check out My 6SN7 Push-pull Flea Amplifier project! PCB COMING SOON!
  Reply With Quote
Old 25th June 2019, 07:49 PM   #7
kodabmx is offline kodabmx  Canada
Affordable triode connected sweep tube amps.
diyAudio Member
 
Join Date: Oct 2011
Location: Toronto
Ideas for a low power amp that is bigger than a flea amp. 5-10W out?
Meh. The bias supply on my monoblocs is -110V. Just surprised, but i guess I''ve need many more volts to run a trioded 6P45S like that.
  Reply With Quote
Old 27th June 2019, 01:52 PM   #8
Bigun is offline Bigun  Canada
diyAudio Member
 
Bigun's Avatar
 
Join Date: Jan 2009
Location: Waterloo, ON or Herefordshire UK
Ideas for a low power amp that is bigger than a flea amp. 5-10W out?
low heat... I remember 6V6 has fairly low heater current at 450mA for similar plate current to the sweep tubes.

Use an SMPS for the heater will save some heat, one of those transformerless lighting modules which give out 12V could power two tubes in series.

SS rectifier saves a lot of heat too

transformer phase splitter saves heat, or use a SS paraphase
__________________
"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 27th June 2019, 02:31 PM   #9
kodabmx is offline kodabmx  Canada
Affordable triode connected sweep tube amps.
diyAudio Member
 
Join Date: Oct 2011
Location: Toronto
Ideas for a low power amp that is bigger than a flea amp. 5-10W out?
I considered using 6P1P which is 6V6 in a 9 pin bottle with a bastard pinout but for another 3 watts of heater, I can use 6P43P and get twice the power.

A transformer PI is a good idea, but I don't have any. I have small toroid power transformers, but I'm read that they have fairly high capacitance and need to be "driven".

So right now, I'm thinking 6F12P VA/PI driving 6P43P in triode. 3K RLa-a. 280V or so. Biased at 20mA to start and see how it performs biased that cold.
I'll be using SS rectification for sure on the power stage, and a CLC filter.
The heaters will be AC from a 30VA transformer (which co-incidentally just happens to be how much heater power the tubes need, and an SMPS for a DC converter for the 380V I use for the VA/PI. Might use another for bias voltage, might use a transformer. Not sure yet
  Reply With Quote
Old 27th June 2019, 03:32 PM   #10
wiseoldtech is offline wiseoldtech  United States
diyAudio Member
 
wiseoldtech's Avatar
 
Join Date: Dec 2018
Location: Philadelphia Pa USA
A nice UL, (or triode connected) design is one I'm fond of, and enjoyed for years now without an issue.
Attached Images
File Type: jpg Ultralinear-EL84amp.jpg (291.6 KB, 481 views)
  Reply With Quote

Reply


Ideas for a low power amp that is bigger than a flea amp. 5-10W out?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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Flea Power Amplifier nnx Solid State 26 5th May 2019 11:21 PM
Flea power 6N6P PPP amp! kodabmx Tubes / Valves 29 17th August 2018 04:08 AM
FH and Flea power amp, buying some kit sarelwagner Full Range 1 1st May 2015 01:57 AM
Flea-power class-A2 using a power opamp driver pmillett Tubes / Valves 19 5th June 2012 10:59 PM
Flea power for cheap OPT's? leadbelly Tubes / Valves 5 25th August 2007 03:10 AM


New To Site? Need Help?

All times are GMT. The time now is 08:16 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki