Well I had heard that in triode the 6av5 mimics (to a large degree) our good friend the 2A3, so I figured it would sound decent enough. Your experiments are pretty exciting considering how cheap these things are, I don't mind screwing up a 2 dollar tube in the name of good sound! As far as the 6146 family goes, I have always heard that the screen voltage limits were hard and fast, that's why I was excited to read Grimwood's ideas about using them to their full potential for audio without exceeding those limits. I may try something with them in the future sice they do have a lot of power potential.
Isaac
Isaac
I have heard the 2A3 rumor but I didn't buy it since the two tubes are so different. Then there was another rumor that Sylvania had actually built some triode wired 6AV5's and sold them as 6B4's to fulfill a military contract. I didn't buy that one either.
Well go to Angela Instruments web page:
http://www.angela.com
Click on Tubes, then click on The Tube Gallery, Scroll down to the very last tube and see it for yourself. It is marked 6B4G and it clearly has multiple grids and an indirectly heated cathode. Looks like a 6AV5 to me. A 6B4 is an octal 6A3 which is a 6 volt 2A3. Now the rumors begin to make sense. It also explains that even Sylvania beleives that these tubes can take 275 volts.
Well go to Angela Instruments web page:
http://www.angela.com
Click on Tubes, then click on The Tube Gallery, Scroll down to the very last tube and see it for yourself. It is marked 6B4G and it clearly has multiple grids and an indirectly heated cathode. Looks like a 6AV5 to me. A 6B4 is an octal 6A3 which is a 6 volt 2A3. Now the rumors begin to make sense. It also explains that even Sylvania beleives that these tubes can take 275 volts.
Hey guys...
I just came across the attached schem. Simple 6146 pp from 1951. It looks like just what I had in mind when we started this thread.
Have a scan and let me know what you think, please.
Do either of you think that the trafos will be hard to get, or will std Hammonds work here?
It is far higher power than I was after but I have never been sorry for having more power
Cheers
Jess
BTW: I had to resize (shrink) the original schem to attach. If you would like the full sized one, email me and I will send it along
I just came across the attached schem. Simple 6146 pp from 1951. It looks like just what I had in mind when we started this thread.
Have a scan and let me know what you think, please.
Do either of you think that the trafos will be hard to get, or will std Hammonds work here?
It is far higher power than I was after but I have never been sorry for having more power
Cheers
Jess
BTW: I had to resize (shrink) the original schem to attach. If you would like the full sized one, email me and I will send it along
Attachments
This should work well with modern transformers, if you can find a combination of off the shelf transformers that can provide the necessary voltages. I can't quite read the details, but do you have the impedance specs on the output transformer?
In any case DO NOT install the capacitor shown that connects one side of the power line to chassis ground. That used to be common in the past, but 55 years of shocking experiences have told us that it doesn't work. Use a 3 wire cord and ground the chassis.
In any case DO NOT install the capacitor shown that connects one side of the power line to chassis ground. That used to be common in the past, but 55 years of shocking experiences have told us that it doesn't work. Use a 3 wire cord and ground the chassis.
Doesn't seem to be any trafo specs that I can make out. OPT seem to be ct primary, 3-tap sec - pretty normal. The plate DC on the schematic is 750V, with B+ at 375v
As said, I have the detailed hi(er)-res pix if you want it.
Got it! Actually, I have a lot of listening to experienced fellows like you before I begin to build something like this.BTW: is that a REGULATED ps?
The plate voltage is not regulated, but the screen voltage is. This is exactly what you need with these tubes.
Lacking impedance data on the transformer in the original design, you are going to need an educated guess. The plate voltage of 750 is the max for this tube with this voltage you would need an 8K ohm transformer and get about 100 to 120 watts. Hammond does not make this transformer, although it could be found. If you don't need this kind of power I would use a lower plate voltage, and get a lower power output. Your tubes will last longer.
At 600 volts you would get over 90 watts with a 6K ohm transformer and 80 watts with a 7K ohm transformer. The higher impedance transformer offers slightly lower distortion to go with the lower power.
At 450 volts you will get 60+ watts with a 4K ohm transformer, and 50 or so with a 6K transformer. Same story with the distortion.
So you need to pick a desired wattage, or a close guess. The higher power requires more money in transformers, and power supply parts. Then you can pick an output transformer.
Hammond lists 3 transformers for use with a pair of 6146's. To squeeze the most power from a modest power supply, use the 1650N (4300 ohms) run it at 500 volts or less. The 1650P (6600 ohms) would offer less power in the same amp at lower distortion. It could also operate at up to 600 volts to get more power. If you have the space and the money the 1650R (5000 ohms) would provide the most power and could provide 75 watts at 500 volts.
If this was my choice, and a first amp. I would use the 1650P and set up the power supply for something between 425 and 465 volts using 500 volt capacitors. Any higher voltages get more complicated quickly. You could expect 50 watts or more from this combination.
Hammond only makes one transformer that has the power capability to adequately support both channels drivem to full power. That is the 278CX. It does not have 5 volt windings. You could use a SS rectifier, or extra transformers. The voltage might be over 500 with SS, you would need HV caps.
If you don't plan to run the amp at full volume a lot (I don't think so) you could use a smaller transformer. The other possibility is a seperate power supply for each channel.
Lacking impedance data on the transformer in the original design, you are going to need an educated guess. The plate voltage of 750 is the max for this tube with this voltage you would need an 8K ohm transformer and get about 100 to 120 watts. Hammond does not make this transformer, although it could be found. If you don't need this kind of power I would use a lower plate voltage, and get a lower power output. Your tubes will last longer.
At 600 volts you would get over 90 watts with a 6K ohm transformer and 80 watts with a 7K ohm transformer. The higher impedance transformer offers slightly lower distortion to go with the lower power.
At 450 volts you will get 60+ watts with a 4K ohm transformer, and 50 or so with a 6K transformer. Same story with the distortion.
So you need to pick a desired wattage, or a close guess. The higher power requires more money in transformers, and power supply parts. Then you can pick an output transformer.
Hammond lists 3 transformers for use with a pair of 6146's. To squeeze the most power from a modest power supply, use the 1650N (4300 ohms) run it at 500 volts or less. The 1650P (6600 ohms) would offer less power in the same amp at lower distortion. It could also operate at up to 600 volts to get more power. If you have the space and the money the 1650R (5000 ohms) would provide the most power and could provide 75 watts at 500 volts.
If this was my choice, and a first amp. I would use the 1650P and set up the power supply for something between 425 and 465 volts using 500 volt capacitors. Any higher voltages get more complicated quickly. You could expect 50 watts or more from this combination.
Hammond only makes one transformer that has the power capability to adequately support both channels drivem to full power. That is the 278CX. It does not have 5 volt windings. You could use a SS rectifier, or extra transformers. The voltage might be over 500 with SS, you would need HV caps.
If you don't plan to run the amp at full volume a lot (I don't think so) you could use a smaller transformer. The other possibility is a seperate power supply for each channel.
As stated, raw power is not a priority. 50-60w is PLENTY! But, I am not clera on the relationship between trafo impedance and distortion. Do you know of a reference on the subject - or a reading list? This interests me.
For a while now I have been thinking about a pair of monobloks rather than a stereo pwr amp.
Hey, thanks TubeLab, this is very informative...
Jess
I have not done a major update to the web site in a long time because I was running near the bandwidth limit for my web hosting plan. When you go over your limit it is like using too many minutes on your cell phone, it cost money. Sometimes a lot of money. I noticed a long time ago that NEW content on the site causes a lot of interest, which gets a lot of hits, I get charged for this. I was limiting the addition of new content to the site to eliminate these overage costs. The hurricane pictures were bandwidth hogs. They generated far more interest than I expected.
As of the first of this year I have a new web hosting plan with more room than I can use (for now) so I will be adding new content as fast as I can get it prepared. Since many of my older experiments were not well documented (if at all) I will need to recreate many of them. Most of the experimenting that I have done in the past 2 years is documented on paper at least, and many were photographed. The experiments that were chronicled in this forum will be posted on the site when I get the time. The older stuff will follow. I have photographed many of my old paper schematics, and will be adding them also.
I have had zillions of e-mails asking for the construction manual for my SE amp board, and for a cookbook approach to PowerDrive, so those will be posted first.
As of the first of this year I have a new web hosting plan with more room than I can use (for now) so I will be adding new content as fast as I can get it prepared. Since many of my older experiments were not well documented (if at all) I will need to recreate many of them. Most of the experimenting that I have done in the past 2 years is documented on paper at least, and many were photographed. The experiments that were chronicled in this forum will be posted on the site when I get the time. The older stuff will follow. I have photographed many of my old paper schematics, and will be adding them also.
I have had zillions of e-mails asking for the construction manual for my SE amp board, and for a cookbook approach to PowerDrive, so those will be posted first.
6146 PP Power amps
G'day Jess .... did u ever get ur 6146 based amps up n running? Despite all the conjecture and speculation in a lot of the threads I don't remember anyone ever actually saying they had built or heard a 6146 based amplifier.
It may interest you to know that DGC Haire built a lot of Theatre amps for the Cinerama group - (do a google and u'll get an idea of this wide screen 6 channel discrete audio theatre process) ... now these power amps used a pair of 6146 in PP and used the 6146 optimally. They had a choke input HT supply, seperate regulated screen supply with adjustable 180vdc-240vdc from a 6BL7+12AX7 reg. and used 6072+5814 for input & phase splitter.
They were in service at many theatres from mid 50's when they were designed and built ... till late 70's in some cases(I'm only talking about Australia here as I have no info on other countries - Altec & RCA I'm told also built amps for the Cinerama system in the US). From all reports they were extremely reliable and excellent sounding. Many ended up in audiophile systems with the original input transformer(to interface with the projectors) and tone control stage disconnected... allen wright modified a pair minimally for a guy who was driving the big accustats and the owner told me it was the best sound he had ever heard in his audio room. When I met him he was driving the accoustats with electrocompaniet amps and the set-up sounded very good. Unfortunately the cineramas went underwater in a flood in late 80's and a dumb tech turned them on b4 the iron was fully dried out !! poof!! however I inherited one full set of the original unpoofed iron and have been looking for another to complete a stereo pair ever since. Obviously I never found another set so I utilised the great chassis to build an updated version as I said. My iron is all dble C core and uses 2 x 350v windings summed through a differential choke to give around 600v on the plates of the 6146. This yields a very stiff HT supply. Just about everything else is the same as the originals including the input and screen regs, although I did not utilise tube rectification like the originals. If I had the room I would have utilised 6AU4 TV damper diodes, but for 2 x 350v windings thats 8 x octals per chassis!!
The 6146 is an "excellent bottle" as the Maestro article says, and does not appear to have a sonic flavor of its own if done correctly in the right circuit to optimise its potential.
Acrosound wouldn't have used it if it wasn't and neither would the DGC Haire people. These amps were designed by professionals to excel in their applications ... not by DIYers. But as they say for every expert there is an equal and opposite expert!!
Also there was a schematic of The Maestro cutter-head amplifier from the AES journal early 50's ... I'm told this was what sparked interest amongst audio design engineers for use of the 6146 in audio applications.
I have a copy of the original article and the original DGC Haire (they used Kenyon Transformer Coy NY iron in the amps) schematic if you are interested .. tropicalblayney@optusnet.com.au ... I also have 2 x modified original mono-block dgc haire chassis - they are now rigged for 4 x 6146 per chassis ... and I have 3 pairs of different output Tx to play with ... 2 x pairs include tertiary windings. The thing with tertiary windings is that you get decreased distortion and the ability to utilise the optimised UL concept dennis talks about.
So if the project is still going email me and I will send the schematics to you. I don't have them scanned - too large and messy and don;t have the time to engage in discussions about the pros & cons of the 6146 ... I've heard them and built amps with them. As for ampegs problems with them ... They were used in australia in audio and guitar amps by Lennard for quite a few years with no reliability probs ... but I think its fair to say that a lot of design considerations for guitar amps are at odds with how you would design for high quality audio. Seems to me that guitar amp manufacturers will push to the limit and under-design rather than over design for both economic and distortion reasons ... look at the output & mains Tx on some guitar amps!!
cheers .... cb
G'day Jess .... did u ever get ur 6146 based amps up n running? Despite all the conjecture and speculation in a lot of the threads I don't remember anyone ever actually saying they had built or heard a 6146 based amplifier.
It may interest you to know that DGC Haire built a lot of Theatre amps for the Cinerama group - (do a google and u'll get an idea of this wide screen 6 channel discrete audio theatre process) ... now these power amps used a pair of 6146 in PP and used the 6146 optimally. They had a choke input HT supply, seperate regulated screen supply with adjustable 180vdc-240vdc from a 6BL7+12AX7 reg. and used 6072+5814 for input & phase splitter.
They were in service at many theatres from mid 50's when they were designed and built ... till late 70's in some cases(I'm only talking about Australia here as I have no info on other countries - Altec & RCA I'm told also built amps for the Cinerama system in the US). From all reports they were extremely reliable and excellent sounding. Many ended up in audiophile systems with the original input transformer(to interface with the projectors) and tone control stage disconnected... allen wright modified a pair minimally for a guy who was driving the big accustats and the owner told me it was the best sound he had ever heard in his audio room. When I met him he was driving the accoustats with electrocompaniet amps and the set-up sounded very good. Unfortunately the cineramas went underwater in a flood in late 80's and a dumb tech turned them on b4 the iron was fully dried out !! poof!! however I inherited one full set of the original unpoofed iron and have been looking for another to complete a stereo pair ever since. Obviously I never found another set so I utilised the great chassis to build an updated version as I said. My iron is all dble C core and uses 2 x 350v windings summed through a differential choke to give around 600v on the plates of the 6146. This yields a very stiff HT supply. Just about everything else is the same as the originals including the input and screen regs, although I did not utilise tube rectification like the originals. If I had the room I would have utilised 6AU4 TV damper diodes, but for 2 x 350v windings thats 8 x octals per chassis!!
The 6146 is an "excellent bottle" as the Maestro article says, and does not appear to have a sonic flavor of its own if done correctly in the right circuit to optimise its potential.
Acrosound wouldn't have used it if it wasn't and neither would the DGC Haire people. These amps were designed by professionals to excel in their applications ... not by DIYers. But as they say for every expert there is an equal and opposite expert!!
Also there was a schematic of The Maestro cutter-head amplifier from the AES journal early 50's ... I'm told this was what sparked interest amongst audio design engineers for use of the 6146 in audio applications.
I have a copy of the original article and the original DGC Haire (they used Kenyon Transformer Coy NY iron in the amps) schematic if you are interested .. tropicalblayney@optusnet.com.au ... I also have 2 x modified original mono-block dgc haire chassis - they are now rigged for 4 x 6146 per chassis ... and I have 3 pairs of different output Tx to play with ... 2 x pairs include tertiary windings. The thing with tertiary windings is that you get decreased distortion and the ability to utilise the optimised UL concept dennis talks about.
So if the project is still going email me and I will send the schematics to you. I don't have them scanned - too large and messy and don;t have the time to engage in discussions about the pros & cons of the 6146 ... I've heard them and built amps with them. As for ampegs problems with them ... They were used in australia in audio and guitar amps by Lennard for quite a few years with no reliability probs ... but I think its fair to say that a lot of design considerations for guitar amps are at odds with how you would design for high quality audio. Seems to me that guitar amp manufacturers will push to the limit and under-design rather than over design for both economic and distortion reasons ... look at the output & mains Tx on some guitar amps!!
cheers .... cb
Nope!
Some wonderful info, Stepitup. I had sort of given up hope that anyone knew of any audio uses for these very pretty and seemingly well-made VTs.
I will email you off-line about a schematic, but you might want to post it - who knows, we might spark some interest and soon every NOS 6146 bottle in every nook and cranny of the planet will be snapped up by over-wealthy DIYers and soon they will go for $75 ea and...
On second thought, don't post anything - we'll keep it our secret Actually, it would be very interesting to get some enthusiasm going for a new and 'undiscovered' VT - maybe someething fresh for all of the experts out there.
Thanks for all the info.
Jess
If you really want to play with the 6159 family of tubes, you could probably make your life easier by going to a Hamfest or on Ebay and picking up a Heathkit HP-23 or later series power supply.
It will supply the needed high voltage, the screen voltage, an adjustable negative bias, and filament power. They are ugly, but cheap and widely available. A good hosing down at a car wash and some new caps and they would probably be like new. You could also just rob the parts and build them into a better looking supply with some screen voltage regulation.
Mike Bryce sells a drop in update board for the HP23 that has all new components and screen regulation built in (http://www.theheathkitshop.com/hp23r.html).
If you just want a transformer and / or choke(s), Peter Dahl Co. (www.pwdahl.com) has all types of high voltage transformers and equipment in their ham catalog, but this is much more expensive than just using a beater power supply.
Let us know how it works for you. I have a bunch of this family of tubes, and power supplies at hand, so I am definitely interested in your results.
edit: Oops, I see you have decided not to pursue the project. Maybe the above source of easy, cheap power will get you reinterested!
Win W5JAG
It will supply the needed high voltage, the screen voltage, an adjustable negative bias, and filament power. They are ugly, but cheap and widely available. A good hosing down at a car wash and some new caps and they would probably be like new. You could also just rob the parts and build them into a better looking supply with some screen voltage regulation.
Mike Bryce sells a drop in update board for the HP23 that has all new components and screen regulation built in (http://www.theheathkitshop.com/hp23r.html).
If you just want a transformer and / or choke(s), Peter Dahl Co. (www.pwdahl.com) has all types of high voltage transformers and equipment in their ham catalog, but this is much more expensive than just using a beater power supply.
Let us know how it works for you. I have a bunch of this family of tubes, and power supplies at hand, so I am definitely interested in your results.
edit: Oops, I see you have decided not to pursue the project. Maybe the above source of easy, cheap power will get you reinterested!
Win W5JAG
Good tip.
My solution was to watch the test equipment section on eBay - I bought a Scientific Instruments 0-1000V / 0-200ma regulated lab bench ps for $80. I still have to provide filament, but the big HT supply makes it so easy to provide regulated B+ with current-limited o/p that I could not now do without it.
I do intend to pursue the project - this bottle has me mightly intrigued.
You can count on it! This project marks my departure from building OPD (other people's designs). This one will be me working out the math, poring over data sheets and reading reams of stuff about transformers - very likely without understanding it any better
If I do succeed in getting any tunes out of this project, you can bet that I will want to blab it all over this forum.
Jess
Hi All,
I also planned to make a SET with this 6146, Does anyone have the schematic ? if so pls send me one at : unoselecta@yahoo.com (no need PP circuit, already have it) . Many Thanks.
Rgds,
Ado
I also planned to make a SET with this 6146, Does anyone have the schematic ? if so pls send me one at : unoselecta@yahoo.com (no need PP circuit, already have it) . Many Thanks.
Rgds,
Ado
The low screen voltage rating of the 6146 makes it a lousy triode and UL is only practical with a separate winding. In most instances you will need to run it as a pentode with lots of feedback. One thing that may not be clear from the spec is that you may be really sorry if you put much more than 200V on the screen grid. 
It's not particularly popular with audio designers for a reason.
IMHO You would be far better off with a triode connected KT88/6550 - better linearity, better sound, and far easier to design with.
The AMPEG SVT used the 6146 in its first incarnation which was quickly replaced with a version using 6550 due to serious reliability problems.
Just my two cents worth.
It's not particularly popular with audio designers for a reason. IMHO You would be far better off with a triode connected KT88/6550 - better linearity, better sound, and far easier to design with.
The AMPEG SVT used the 6146 in its first incarnation which was quickly replaced with a version using 6550 due to serious reliability problems.
Just my two cents worth.
tubelab.com said:
...but they still blew up because of directly connected cathode followers ... Cold solder, dead tube, or just bad contact in the socket between grid and resistor... strong pulse on grids of output tubes... spark between 2 and 3 legs... blown anti-hum symmetry resistors in filaments, probably output tranny...
It is a myth about bad output tubes (urban legend). The problem was in some overlooked details (the Devil is in details!)
With that's all "unsave parameter" 6146 ,make me more desire to built it on SE line due to High power posibly deliver rather than use other popular tube with very high cent & Low power. Two weeks ago I just succeded to built SE using rare EC360 with myown Circuits design(No body have SE schematic for this Tube) and My boss love its sound, He asked me to give him a price. Base on it I think I can do the same to this small giant 6146 even nobody give me the Schematic(hope someone do, to make me easier)...just waiting for the tube shipping
6146 SET
Hi All,
Finally last nigth just finished my 6146 SE(after I broken 1 Tube for the expariment), The sound much better than my previous EC360 SE maybe caused by the bigger Power Out from 6146 ... Too bad (or too good for me my friend asked this new SET for him, so I will built the new High Power SET using 6012 Tube ... again Nobody have the SE schematic for this Cute Giant Tube....but no big deal for me, I think it's easier than 6146...can't wait to hear the sound...It would be my Serious SET coz I'll used my Topgrade component & won't "give it" to anyone ....
Rgds,
Ado
Hi All,
Finally last nigth just finished my 6146 SE(after I broken 1 Tube for the expariment), The sound much better than my previous EC360 SE maybe caused by the bigger Power Out from 6146 ... Too bad (or too good for me
my friend asked this new SET for him, so I will built the new High Power SET using 6012 Tube ... again Nobody have the SE schematic for this Cute Giant Tube....but no big deal for me, I think it's easier than 6146...can't wait to hear the sound...It would be my Serious SET coz I'll used my Topgrade component & won't "give it" to anyone ....Rgds,
Ado
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