6HV5A Single Ended Amp - Page 3 - 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 3rd May 2006, 02:09 PM   #21
diyAudio Member
 
rcavictim's Avatar
 
Join Date: Jun 2004
Location: Next to an open wormhole NW of Toronto
Quote:
Originally posted by tubelab.com
The king of Mu has to be the 6BK4. Mu of 2000, to bad it is totally useless for audio (I tried).
I thought the 6BK4 might have some usefulness as an output tube used to drive some sort of electrostatic speaker system where high anode voltage up around 10 kV might be employed. The tube can handle up to about 50 kV IIRC.

What plate voltage did you try it at for audio, as an output or linestage/preamp?
__________________
On April 01,2012, my radioastronomy Project TARGET SETI search succeeded. The signal came via extradimensional subspace, not radio waves. I now get a lot of 'visitors'. I took my avatar pic of one friend watching me in my work yard from just 20 ft. away.
  Reply With Quote
Old 3rd May 2006, 02:28 PM   #22
diyAudio Member
 
tubelab.com's Avatar
 
Join Date: Jul 2005
Location: West Virginia panhandle
I just connected it up to my power supplies and turned the knobs trying to get it to conduct. At 550 V on the plate and +25 on the grid (limit of my power supplies) I was drawing a few microamps. The behavior was very nonlinear. The thought was for preamp applications, since max plate current is 2 mA by some books and 1.6 mA in others. It is designed to operate with 26 KV on the plate. The maximum ( non conducting ) voltage is 46 KV in my old RCA book. No max ratings are given in my newer RCA book.

I did not consider HV applications for electrostatic speakers, since I have no room for them.
__________________
Too much power is almost enough! Turn it up till it explodes - then back up just a little.
  Reply With Quote
Old 3rd May 2006, 05:45 PM   #23
diyAudio Member
 
wrenchone's Avatar
 
Join Date: Feb 2004
Location: Silicon Valley
The gain and transconductance figures for the 6HV5A are for high plate voltage and high peak current, well outside the range where one could operate the tube continuously without melting it into a pile of glittering slag. The mu should be about the same at lower current, but I would expect a much lower transconductance than the figure of 30k mumhos cited in the data sheet. At 1.2kV plate voltage, 35W dissipation is only 29 mA.
  Reply With Quote
Old 7th September 2006, 07:10 PM   #24
diyAudio Member
 
Join Date: Feb 2006
Location: Ft Laud. Fla
Default Compactron idea #2

How about a push-pull set of 33GY7A? Reasonable dissipation and your power supply diodes built in. Build 'em in stereo and hang the four heaters in series from a isolation transformer and the dampers as a doubler for + 300 or so B voltage.
Not enough sleep and too much coffee makes me get strange thoughts
my2c
Jorge
  Reply With Quote
Old 19th September 2006, 02:40 AM   #25
diyAudio Member
 
tubelab.com's Avatar
 
Join Date: Jul 2005
Location: West Virginia panhandle
I found soma tubes in the warehouse that look similar to the 6HV5. The 6JH5 and the 6JK5 look like the 6HV5 and have the same specs. The 6HS5 has a wimpier plate and is only rated for 30 watts.

I tried connecting the 6JK5 up to my power supply and twisting a few knobs to see what kind of voltages this tube would need to work. With 400 volts on the plate and ZERO volts on the grid (beam plates connected to cathode) the tube was drawing about 15 mA. If this tube was going to work on a reasonable plate voltage, positive grid voltage would be needed.

OK, I turned the grid voltage up, with +5 volts on the grid, the tube was drawing 200 mA. I didn't have time to plot curves to determine linearity. From this 5 minute test, it seems that this tube could operate from a 400 to 500 volt supply with positive bias. Gain is very high.

Just to see what would happen, I connected the beam plates up to the plate. Zero bias current was 50 mA and oscillation was present. Any knob twisting caused extreme TV jamming oscillation and 200 mA of current.

Some time in the future, I will plot some curves, but I don't think that it will be any time soon.
__________________
Too much power is almost enough! Turn it up till it explodes - then back up just a little.
  Reply With Quote
Old 19th September 2006, 03:45 AM   #26
diyAudio Member
 
wrenchone's Avatar
 
Join Date: Feb 2004
Location: Silicon Valley
When I finally get around to building the 6HV5A amp, I'll be using plate and grid stoppers, and some cathode resistance on each tube - otherwise, I'd expect them to burst into song, especially operating in parallel. The beam plates will be nailed to the cathode right at the socket. As far as I've seen, the only 6HV5As worth messing with are from GE and Westinghouse - the plates on these are 20-30% larger than other brands. GE boasts of a superior bonded cathode coating that reduces the incidence of shorts. Given the high gain, the cathode to grid spacing must be microscopic...
  Reply With Quote
Old 19th September 2006, 01:08 PM   #27
diyAudio Member
 
tubelab.com's Avatar
 
Join Date: Jul 2005
Location: West Virginia panhandle
I don't have a dead one to dissect, YET. I can see inside that the grid is made of a lot of closely spaced turns of really fine wire.

The 6HV5's that I have are both GE's. The other tubes are various brands. I was torturing a Zenith 6JK5 last night. Construction looks identical to the GE 6HV5. I had to go up to 55 watts to get the plate to glow, and even at that level you had to turn the room lights off to see it.

All of the tubes that I have look identical, except for the 6HS5. It has much smaller plates, and it is a GE.

I am trying to dream up a minimum parts amplifier, but it hasn't come to me yet. I don't have time to build it yet anyway. I was digging through my warehouse looking for some small dual triodes when I found a big box marked sweep tubes. I couldn't remember what I put in the box, so I opened it and pulled out about 5 of these pulse regulator tubes. At the time I boxed up the tubes I did not know about the 6HV5, so I thought it was just annother sweep tube.

About a year ago I found that Jack at Electra-Print had used this the 6HV5 as a driver tube. 700 volts, cathode bias (negative grid voltage).

http://www.electra-print.com/hyperdrive.html
__________________
Too much power is almost enough! Turn it up till it explodes - then back up just a little.
  Reply With Quote
Old 19th September 2006, 09:51 PM   #28
diyAudio Member
 
wrenchone's Avatar
 
Join Date: Feb 2004
Location: Silicon Valley
Tubelab -
I looked up the 6JH5, and it takes a bit more filament current than the 6HV5A - 2.5A vs. 1.6A. I would suspect this means a somewhat larger cathode structure and more peak current capability. At 700V plate voltage, though, the difference may not mean too much. The 6JH5 may be a better choice if one is trying to squeeze out power using a lower plate voltage. I'm gratified but not entirely surprised by the results of your power torture test - those tubes have big, big plates.

I'm planning to take an old Hallordson 540VCT transformer and run it with a full wave bridge to get around 700V to run the 6HV5As. What's holding me up is figuring out a sneaky, sleazy way of getting a lower supply voltage for the driver tubes without having to throw in another transformer or blow big power in dropping resistors. If I have to use another transformer, one sneaky way of proceeding might be to dedicate a spare filament winding to driving a filament transformer backwards. If I use a transformer with dual/230V primary winding, I could get 300VDC or so to run the drivers.
  Reply With Quote
Old 19th September 2006, 11:23 PM   #29
diyAudio Member
 
rcavictim's Avatar
 
Join Date: Jun 2004
Location: Next to an open wormhole NW of Toronto
Quote:
Originally posted by wrenchone
Tubelab -


I'm planning to take an old Hallordson 540VCT transformer and run it with a full wave bridge to get around 700V to run the 6HV5As. What's holding me up is figuring out a sneaky, sleazy way of getting a lower supply voltage for the driver tubes without having to throw in another transformer or blow big power in dropping resistors.

If you reference the negative output of your 700 VDC bridge circuit to chassis you can get +350 VDC to chassis from the xfmer HV winding CT.
__________________
On April 01,2012, my radioastronomy Project TARGET SETI search succeeded. The signal came via extradimensional subspace, not radio waves. I now get a lot of 'visitors'. I took my avatar pic of one friend watching me in my work yard from just 20 ft. away.
  Reply With Quote
Old 20th September 2006, 12:26 AM   #30
diyAudio Member
 
tubelab.com's Avatar
 
Join Date: Jul 2005
Location: West Virginia panhandle
Quote:
If you reference the negative output of your 700 VDC bridge circuit to chassis you can get +350 VDC to chassis from the xfmer HV winding CT.
I was about to say the same thing. Put a bridge across the 540 vct winding and a cap across the bridge. Ground the negative terminal of the bridge. You will have about 700 volts at the positive terminal of the bridge. Connect a cap from the CT of the transformer to ground. Electrolytic is OK. You will magically have about 350 volts at this connection.

If you think about this for a while it is really two seperate full wave power supplies stacked on top of each other. Or it is like the + and - supplies in most SS amps, with the ground in a different place.

Doing this (or any bridge rectifier on a transformer designed for full wave CT operation) will subject the transformer to twice the voltage that it was designed for. Use caution with vintage transformers. I am thinking Antek toroid from Ebay.

Same for the OPT. With 700 volts on the B+, the peak voltage at the plate could go to 1400 volts. I don't think that Hammond had this in mind when they made the 125CSE. Make sure that the cases of these transformers are well grounded, even during testing.
__________________
Too much power is almost enough! Turn it up till it explodes - then back up just a little.
  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
Single Ended, Single driver: In-room distortion measurements Gerrit Boers Full Range 4 27th November 2007 08:12 AM
Single Ended EL-34? jaymanaa Tubes / Valves 11 28th March 2006 10:32 PM
42 single ended ThSpeakerDude88 Tubes / Valves 38 19th November 2005 10:02 PM
Anyone play with the Zen Single-Stage Single-Ended Class A? Rino odorico Pass Labs 13 29th August 2002 09:01 AM


New To Site? Need Help?

All times are GMT. The time now is 12:23 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