Simple is good I realized I should weigh in with a Concept
sorry for not having built this, but I just discovered the contest and all the nonsense, and all the goodness...
Ok now onward my concept for the contest (2) 50bm8's plus (2) 14F7's
with these adding up to 122V in the heater string, heaters to run on line voltage, so no heater transformer...all legal and generally even somewhat same..i.e. as safe as anything run on 120VAC generally
... the high voltage from a 120V-240V line transformer Mouser $15...and I want a 'real' OPT because I think it makes a difference, however I am still looking at some toroid power transformers because many of them really do sound good for cheap $...
ok 2 50bm8's AES $14.20
2 14f7's AES $7.50
Power 120v-240v .3A Mouser $15.00
OPT MPS OT15PP $23.00
so this is $60, and the rest ok I will make it...
the circuit in general: Fender Deluxe (or other) traditional input into Modded Bassman ToneStack i.e. voltage + Cathode follower to eq, then the remaining section as a 'boost' section for extra distortion with a Master volume into a LPT using the two triode sections (5751's almost) of the 50bm8's, into the pentodes of the 50bm8's for 3.5W in SE(with voltage drop via switched divider), and 10W
in PP...
ok good amp unless the heater voltage causes hum, but the sonics of 6bm8 are known and good, and the sonics of the 14f7 are known and good, and each circuit is a simple look up and build, already sorted by Leo Fender himself (except the 50bm8 outputs, which are already sorted by others, and sound quite good)...Is this a Champ beater no, but close, and it probably is a Deluxe beater...so not bad for $100...thanks
(So because of this contest I have had arise in my mind a Champ beater better basically because brick basic begs better blam blamming beyond best) ok so because of this alone thanks because this is a commercial product...which will have a following: yes it is that good...yes unsaid!!!...
good contest...very creative juices flowing thanks
-3db
sorry for not having built this, but I just discovered the contest and all the nonsense, and all the goodness...
Ok now onward my concept for the contest (2) 50bm8's plus (2) 14F7's
with these adding up to 122V in the heater string, heaters to run on line voltage, so no heater transformer...all legal and generally even somewhat same..i.e. as safe as anything run on 120VAC generally
... the high voltage from a 120V-240V line transformer Mouser $15...and I want a 'real' OPT because I think it makes a difference, however I am still looking at some toroid power transformers because many of them really do sound good for cheap $...ok 2 50bm8's AES $14.20
2 14f7's AES $7.50
Power 120v-240v .3A Mouser $15.00
OPT MPS OT15PP $23.00
so this is $60, and the rest ok I will make it...
the circuit in general: Fender Deluxe (or other) traditional input into Modded Bassman ToneStack i.e. voltage + Cathode follower to eq, then the remaining section as a 'boost' section for extra distortion with a Master volume into a LPT using the two triode sections (5751's almost) of the 50bm8's, into the pentodes of the 50bm8's for 3.5W in SE(with voltage drop via switched divider), and 10W
in PP...ok good amp unless the heater voltage causes hum, but the sonics of 6bm8 are known and good, and the sonics of the 14f7 are known and good, and each circuit is a simple look up and build, already sorted by Leo Fender himself (except the 50bm8 outputs, which are already sorted by others, and sound quite good)...Is this a Champ beater no, but close, and it probably is a Deluxe beater...so not bad for $100...thanks
(So because of this contest I have had arise in my mind a Champ beater better basically because brick basic begs better blam blamming beyond best) ok so because of this alone thanks because this is a commercial product...which will have a following: yes it is that good...yes unsaid!!!...
good contest...very creative juices flowing thanks
-3db
sorry for not having built this, but I just discovered the contest and all the nonsense, and all the goodness...
Ok now onward my concept for the contest (2) 50bm8's plus (2) 14F7's
with these adding up to 122V in the heater string, heaters to run on line voltage, so no heater transformer...all legal and generally even somewhat same..i.e. as safe as anything run on 120VAC generally:cubist:... the high voltage from a 120V-240V line transformer Mouser $15...and I want a 'real' OPT because I think it makes a difference, however I am still looking at some toroid power transformers because many of them really do sound good for cheap $...
ok 2 50bm8's AES $14.20
2 14f7's AES $7.50
Power 120v-240v .3A Mouser $15.00
OPT MPS OT15PP $23.00
so this is $60, and the rest ok I will make it...
This will never fly here, sorry but using a filament string directly driven off mains current/voltage is not an acceptable practice.
Even with amps people call junk bin amps the first thing corrected before use is adding an isolation transformer & proper mains grounding.
Though the design you mention can likely be made to operate and might even sound fantastic, it is also a lethal combination by today's standards.
This won't work for two reasons:
Heater to cathode shorts are not uncommon, as are open ground connections in a live environment. For these reasons connecting line voltage tubes up to the line as they were intended is a good way to get FRIED!!!!!!
Why? Yes the tubes were intended to be wired across the line, but the completed apparatus is enclosed inside a wood or plastic box with no intentional connection to the outside world. A guitar amp has a direct connection from the circuit to the user. A H-K short in any tube could directly connect the user to the wall socket. A sweaty guitar player on stage with a bunch of grounded metal objects could get FRIED!!!!
Use a Triad N-68X isolation transformer to power the amp and make your B+ with a voltage doubler. I am doing it this way in one of my amps.
I can't speak for "legality" but it would NOT pass todays safety standards as defined by UL. There must be a minimum "creepage distance" between the line powered circuits and the user accessable circuits. I believe that distance is 1/4 or 3/8 inch in the US (not totally sure) but the distance between the H and K aren't enough.
The 50BM8 has a 100 mA heater rating. The 14F7 has a 150 mA heater rating. Connecting them in series will cause the 14F7's to receive less than 12 volts. If wiring heaters in series they all must have the same current rating.
I have two amps running series heater strings with 100 mA heaters. The 50BM8 is not in large supply, but if you have them there are two possibilities. The 20EZ7 is a 20 volt 100 mA version of the 12AX7. Unfortunately they are rather rare. The 26AQ6 is a 26 volt 100 mA dual triode with a Mu of 50, not quite a 12AX7. The 18FY6 is a single triode plus two diodes that has the same specs as 1/2 a 12AX7 there are lots of them out there.
As both Trout and tubelab have explained your proposal constitutes an extreme safety hazard and promoting designs that do not fully isolate the end user from AC mains is also a violation of forum policy. Any such proposal discussed here going forward must include mention of full transformer isolation from the mains.Thanks TubeLab...yes Frying...hehe always a scary moment...
yes we don't want to get the guitarists fried...
I apologize for not confirming the heater on the 50bm8...I swear I looked at it though, but I needed two more highmu sections without another tube...
so if you fears are correct then shorts & opens are possible, however we know many guitar amps were built this way( 20 or so different amps in the " Tube Amp" book, in fact with no isolation tranny of any kind)....so yes some problems, however not automatically death inducing....I balance this against the other 5 models like mine, with one isolation tranny( on high side)...
And thanks for your work on my behalf...it is a lot of knowledge work to find the various tube options for me...!!!!
so, however getting the heater string right is the thing, and the solution was/is where I started from the 50L6 or course 50v .15a heater...thus making the string work, but costing me the two triode sections...it is a good tube, so then I realized last night that I could do an Eli Duttman "El Cheapo" (and this is an el cheapo exercise yes) cathode tie thing for the output with a good CCS to force the phase splitting...and dada no need the two sections...however then I must run in Class A, however this is not the end of the world...mmm
So genuine thanks and my preference is not to fry the poor guitarist...so I will think about a "production product" approach for the UL, and for me...different tubes however ....so..mmmm
Sincerely,
-3db
yes we don't want to get the guitarists fried...
I apologize for not confirming the heater on the 50bm8...I swear I looked at it though, but I needed two more highmu sections without another tube...
so if you fears are correct then shorts & opens are possible, however we know many guitar amps were built this way( 20 or so different amps in the " Tube Amp" book, in fact with no isolation tranny of any kind)....so yes some problems, however not automatically death inducing....I balance this against the other 5 models like mine, with one isolation tranny( on high side)...
And thanks for your work on my behalf...it is a lot of knowledge work to find the various tube options for me...!!!!
so, however getting the heater string right is the thing, and the solution was/is where I started from the 50L6 or course 50v .15a heater...thus making the string work, but costing me the two triode sections...it is a good tube, so then I realized last night that I could do an Eli Duttman "El Cheapo" (and this is an el cheapo exercise yes) cathode tie thing for the output with a good CCS to force the phase splitting...and dada no need the two sections...however then I must run in Class A, however this is not the end of the world...mmm
So genuine thanks and my preference is not to fry the poor guitarist...so I will think about a "production product" approach for the UL, and for me...different tubes however ....so..mmmm
Sincerely,
-3db
Sorry Kekinkr etc...I am a Bad Boy...Yes!!!
However this simply forces the creativity to move a little more...sorry for making designs which might fry the guitarist...ok...
However what is exciting is looking around for other non heater string tubes, and having ideas like the 6w6, which I have known about, but always wondered about, and liking the 6AQ5 for some time...and
Seeing Printer2 with the 12AQ5, please forgive me for simply copying, but it does actually save me money @ $2.70 each from AES, and with relatively good supply on ebay....
So thanks for saving me from myself, and not to mention all the unfried guitarists out there who shall now forever remain unfried.!!!
Thanks Printer2 because also I can afford the third 14f7 now, and the rest of my circuit is different from yours, by desire, and yet generally your total cost gives me a good mark to shoot for...
I will fill out the rest of the BOM in the days to come...very refreshing...
Sincerely
-3db
However this simply forces the creativity to move a little more...sorry for making designs which might fry the guitarist...ok...
However what is exciting is looking around for other non heater string tubes, and having ideas like the 6w6, which I have known about, but always wondered about, and liking the 6AQ5 for some time...and
Seeing Printer2 with the 12AQ5, please forgive me for simply copying, but it does actually save me money @ $2.70 each from AES, and with relatively good supply on ebay....
So thanks for saving me from myself, and not to mention all the unfried guitarists out there who shall now forever remain unfried.!!!
Thanks Printer2 because also I can afford the third 14f7 now, and the rest of my circuit is different from yours, by desire, and yet generally your total cost gives me a good mark to shoot for...
I will fill out the rest of the BOM in the days to come...very refreshing...
Sincerely
-3db
Very cool..
Years ago a friend of mine designed an amplifier around a pair of EF86 as output tubes, the OPT had a plate to plate Z of about 140K as memory served - not sure how the winder managed that, but it worked. It sounded pretty good into a Celestion reissue series driver.. (details long forgotten) Output power was less than 1W
Unfortunately this is the case - not sure where the hype about 'bad' transformers for good distortion comes from. Last night I did some recordings with my cheap amp and a good Champ I made a long time ago. The Champ copy has a Hammond 125ESE OT. The Champ copy OBLITERATED my little amp. Much more warm sounding, no nasty distortion. My little champ suffers a real indigestion when I hit the strings real hard. It just distorts too much and NOT in a nice way - a shrill scream that pierces my ears. OK, some people like that but not me. This small OT can't cope with certain notes.
The Champ is a SE amp that runs the tube's plate current through the OPT. If the OPT isn't gapped or severely oversized there will be saturation induced distortion created in the OPT. Saturation sounds rather nasty. If your "OPT" has a center tap try wiring it like a P-P transformer with a load (even a resistor) on the other side to see if that is the issue. A resistor will waste power, but a CCS will not. In my amp I used a self split output stage but the undriven side is more for eliminating OPT saturation than anything else.
I am getting good sound out of both of my budget amps. One uses a 70 volt line transformer and the other uses an Antek power toroid. Both are P-P amps though.
If your OPT can be dissassembled it may be possible to restack the laminations where all the E's and I's line up and make a gap with a few thicknesses of scotch tape.
I just googled up a data sheet, it could have been wrong so double check. I kind of thought it was 150 mA too, but I chose not to use them because they weren't in large supply.
In the radio days the 50L6 was common for the octal output tubes. When miniature tubes appeared the 50B5 was the first output tube to appear. People kept getting zapped by touching the chassis of a radio with a broken knob so UL and others proposed safety standards that became a requirement for selling product. The practice of tying one side of the power line to the chassis became taboo and the 50B5 was repinned to create the 50C5 to satisfy the creepage requirements in effect at the time. It then became common practice to connect a capacitor from the line to chassis ground.
Safety standards have evolved and today we refer to this capacitor as the "death cap". The name is for a good reason since old caps tend to be leaky and leaky caps can fry guitar players. Yes the schematics for these old amps are all over the net, but I would not play one without an isolation transformer between me and the wall outlet. The action of placing ones hand around the neck of the guitar would make it impossible to let go of when a short occurred.
Somewhere back in this thread you can find the schematics of my two designs that are line powered with series heater strings. Both run the tubes off of the B+ supply on DC for zero hum. The little guy makes about 2 watts and the big guy makes 20 watts but it requires a 100 VA isolation transformer.
Nothing to do with this contest but...
Speaking of SE transformers and saturating transformers, I could use a bit of direction. I have an old line powered amp, 12AX7, 35W4, 50C5. The transformer core that the amp uses is a bit small 2" x 1.5" x 0.5", I am guessing it is a 2W mind you I do not know what size a 4W would be for guitar. I want to use the transformer but with a different tube and was thinking of using one of two tubes with it. Either a 6AQ5, lower secondary impedance than the tube is used to but running it at a lower voltage and higher current than would be normal but still within dissipation limits. Using a 25L6, more in line with the secondary impedance but the 50C5 normally puts out 2W where the 25L6 is around 4W but is also rated at 2W at 110V. Not sure which way to go. May use a 12AU6 for the input with a Mosfet follower on it and a Tweed volume-tone arrangement. Just something low power to distort at a low volume.
Speaking of SE transformers and saturating transformers, I could use a bit of direction. I have an old line powered amp, 12AX7, 35W4, 50C5. The transformer core that the amp uses is a bit small 2" x 1.5" x 0.5", I am guessing it is a 2W mind you I do not know what size a 4W would be for guitar. I want to use the transformer but with a different tube and was thinking of using one of two tubes with it. Either a 6AQ5, lower secondary impedance than the tube is used to but running it at a lower voltage and higher current than would be normal but still within dissipation limits. Using a 25L6, more in line with the secondary impedance but the 50C5 normally puts out 2W where the 25L6 is around 4W but is also rated at 2W at 110V. Not sure which way to go. May use a 12AU6 for the input with a Mosfet follower on it and a Tweed volume-tone arrangement. Just something low power to distort at a low volume.
Capacitors are where "The Tone" is at, however...
I don't think I can afford Vintage Bumblebees, or Black Cats here...so
I like PartsExpress Polyproplene Film and Foil Caps @ about $1.oo each in the few stocked values , they sound excellent smooth, detailed, and slightly warm.
However I need eight signal caps here, and I like to bypass the power supply caps with these caps also, in the usual 1% of the bypassed cap ratio. Plus bypassing the Cathode Caps. This means 7 more caps, so 15 Caps total at $1 each...$15.00 is too much...
So, what I have found is Ted Webers shop of Weber speaker fame, has some of the cheapest Caps, and magnetics I have seen. I am ordering a Tweed Bassmand power Transformer for $50 + $9 for top mount end bells, and this compares to $90 or more usually...
and their Polypropylene Film Al Foil caps are...yes!!....$.40 cents each!!!
They say these caps are a 716P style equivalent, I don't know I have not seen or heard them, however for this project they are right in the BallPark!!! ok so 15 Caps @ .40 each for $6.00 total, Ok I can handle...
Also I am seperately using a copy of the Sear Silvertone 1484 output transformer 4k 40w from them (TedWeber)...this is an Ultra Fat Stack transformer for $50, and I doubt that many of the $200+ Fat Stack transformers from Mercury Magnetics are any better...so anyway here is the link ...Enjoy...( and obviously I am not currently getting paid by Weber to say these things)
https://taweber.powweb.com/store/capord.htm
Thanks for all your work, Ladies & Gentlemen,
Sincerely,
-3db
I don't think I can afford Vintage Bumblebees, or Black Cats here...so
I like PartsExpress Polyproplene Film and Foil Caps @ about $1.oo each in the few stocked values , they sound excellent smooth, detailed, and slightly warm.
However I need eight signal caps here, and I like to bypass the power supply caps with these caps also, in the usual 1% of the bypassed cap ratio. Plus bypassing the Cathode Caps. This means 7 more caps, so 15 Caps total at $1 each...$15.00 is too much...
So, what I have found is Ted Webers shop of Weber speaker fame, has some of the cheapest Caps, and magnetics I have seen. I am ordering a Tweed Bassmand power Transformer for $50 + $9 for top mount end bells, and this compares to $90 or more usually...
and their Polypropylene Film Al Foil caps are...yes!!....$.40 cents each!!!
They say these caps are a 716P style equivalent, I don't know I have not seen or heard them, however for this project they are right in the BallPark!!! ok so 15 Caps @ .40 each for $6.00 total, Ok I can handle...
Also I am seperately using a copy of the Sear Silvertone 1484 output transformer 4k 40w from them (TedWeber)...this is an Ultra Fat Stack transformer for $50, and I doubt that many of the $200+ Fat Stack transformers from Mercury Magnetics are any better...so anyway here is the link ...Enjoy...( and obviously I am not currently getting paid by Weber to say these things)
https://taweber.powweb.com/store/capord.htm
Thanks for all your work, Ladies & Gentlemen,
Sincerely,
-3db
Also need a ruling on supplier: ApexJr....
I do a small bit of business with them, and Steve runs a pretty good surplus shop there....In the language of this contest, no parts from vendors with " severly limited supplies "....so I think generally of Steve ( ApexJr) as having hundreds of piece parts in any given value...not thousands, but also not ten....
so if I were to use Steve as a source for an amp that I would make available as a kit, generally I would think I would be ok...if something sells out he typically will get a very similar item within a couple months, no not two days, but not a year either...
ApexJr would be a vender of what I'd call " moderately limited supplies", but what is the ruling for the purpose of this contest???
comments???
thanks,
sincerely,
-3db
I do a small bit of business with them, and Steve runs a pretty good surplus shop there....In the language of this contest, no parts from vendors with " severly limited supplies "....so I think generally of Steve ( ApexJr) as having hundreds of piece parts in any given value...not thousands, but also not ten....
so if I were to use Steve as a source for an amp that I would make available as a kit, generally I would think I would be ok...if something sells out he typically will get a very similar item within a couple months, no not two days, but not a year either...
ApexJr would be a vender of what I'd call " moderately limited supplies", but what is the ruling for the purpose of this contest???
comments???
thanks,
sincerely,
-3db
I don't know if it's gapped or not, it should be since it was in a SE output stage the firt time we met. It really depends on how I play: if I play gentle no problem, if I play agressively like I did last night (madman on) it runs out of steam. It really isn't distortion anymore - it's butchering time. Chops the head off notes in an uncanny fashion. What I'm going to do is inject a dosis of negative feedback (it really needs it), and maybe, if I become desperate enough, turn it into a triode. Anyway, the lack of clean headroom is obvious and there's nothing much to do about that.
Some people say the Champ is a one trick pony, well, this is a 1/2 trick pony. Too short legged. It comes with the price, I shouldn't be looking at its teeth.
Ready for a morning shock? Here are some very unprofessional recordings. These were recorded with a cheap Nikon camera. The clips recorded with a good mike are yet to be compressed - files can't be attached here.
Still shocked? Yeah, that sounded really bad. Wonder how the youtube guys do it, well some of them. There are videos that sound as bad as mine. The real challenge is not about making a cheap amp, the real challenge is to make a decent recording. What a bore!
OK, the reason of my post is that I bought two old tube radios a week ago, Telefunken's, and today I opened the package and ....what a shocker.....it turns out the OT'S fit into my chassis. I thought finding another OT this size was next to impossible. I love all this strange coincidences, the amp was in the death row but now it gets an extension. Not dead yet.
Oh, and don't forget to learn from my failure - if you're going to use a cheap OT do a push pull amp!
OK, the reason of my post is that I bought two old tube radios a week ago, Telefunken's, and today I opened the package and ....what a shocker.....it turns out the OT'S fit into my chassis. I thought finding another OT this size was next to impossible. I love all this strange coincidences, the amp was in the death row but now it gets an extension. Not dead yet.
Oh, and don't forget to learn from my failure - if you're going to use a cheap OT do a push pull amp!
