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Hi, I'm new here.
I wonder does any one happen to have the user manual of Polytone Baby Brute / Baby Taurus? Or maybe can shed some light on how to get nice clean tone out of it? I just bought a used one and puzzling the difference of those 3 "dist" smaller / inner dials. It seems they can't be rolled all the way to zero. Perhaps one of them serves as Gain / Master button like modern amps?
And I have no clue what the "Reverse" switch for...
Last edited by andreshum; 06-13-2022 at 07:06 AM.
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06-13-2022 06:11 AM
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The "reverse" is like taking a two-prong wall plug and flipping it over. It may buzz less one way or the other.
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Anything here help?
polytone.htm
What happens when you use the brite/dark switch?
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Originally Posted by andreshum
Hi, I'm new here.
I wonder does any one happen to have the user manual of Polytone Baby Brute / Baby Taurus? Or maybe can shed some light on how to get nice clean tone out of it? I just bought a used one and puzzling the difference of those 3 "dist" smaller / inner dials. It seems they can't be rolled all the way to zero. Perhaps one of them serves as Gain / Master button like modern amps?
And I have no clue what the "Reverse" switch for...
Keep the gain switch towards the negative. That should disable the center pots for distortion and dist eq.
Your bass and treble are the outside pots, Try bass at 7 (or right below where it's overpowering) and treble at 5, The mids is the center of the bass pot. Sweep to taste.
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The red/center knob on the volume control (I can't remember if it's red on my Taby Taurus or not) is the distortion gain control. If you turn it counter-clockwise all the way, it should click off. If it hasn't clicked, it's not turned off. It's like having a two channel amp with only one input, so there is a switch for the distortion channel. It happens to be in the knob.
Mine is slightly different without the distortion EQ and boost controls, but I would try turning those all the way counterclockwise and seeing if they click, as well. The gain switch has more noticeable effect on the distortion channel, but it is like having a high and low input on a Fender amp- just on a switch rather than having two inputs.
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Great, I'm gonna give it a try although I'm not entirely sure what that means lol. Thanks Originally Posted by BigDaddyLoveHandles
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I've already looked through that, no luck. Originally Posted by lammie200
The brite / dark switch does exactly that, changing the overall tone in addition to the normal 3 way eq
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If I turn the distortion control counter-clockwise all the way, it does click. But what it does is turn on the heavy distortion mode, instead of overdrive Originally Posted by Cunamara
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That switch flips the hot and neutral wires in your power cord to make the normally hot lead neutral and the normally neutral wire hot. Assuming you have a 3 prong plug that's properly connected (i.e. the amp chassis is grounded), that switch should have no effect unless the power line to which you're connected is wired backwards. Back when I was starting out, many guitarists who'd been shocked by an amp with a 2 prong plug carried a cheap plug-in polarity tester to check an outlet before plugging in. When I was in high school, I got one memorable shock when I touched a microphone and my guitar strings at the same time - I remember the event like it was yesterday! The first legal requirement for 3 prong plugs on some applicances was issued in 1969, at which time only about half of US homes even had grounded outlets. As Polytone was started in the '60s, I'm sure there are some models still out there with ungrounded chassis and 2 wire power cords. Originally Posted by andreshum
Some Fenders and other amps with 2 prong plugs had a capacitor known as "the death cap" that connected one power wire to the chassis to reduce electrical noise. If the cap failed and shorted, it made the amp chassis hot - many musicians have been shocked. Keith Relf (Yardbirds) was electrocuted by his guitar because of this in the mid-'70s. Even if the cap is good, it bleeds a little current to the chassis and will give you a tingle (or more) if you're touching your guitar strings or amp and a grounded surface or object at the same time. It's the main reason that any vintage amp being used today should be converted to a properly wired 3 lead power cord.
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Changing the A/C polarity has an effect on the level of hum noise. My polytone is noticeable noisier in one polarity position than the other regardless of where it's plugged in. Apparently the noise and polarity relationship depends on the orientation of the primary winding of the power transformer. Originally Posted by nevershouldhavesoldit
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Sorry. Perhaps I should have said "...that switch should have no effect unless the power line to which you're connected or the power transformer's primary is wired backwards, the amplifier has been repaired or modified to deviate in some way from original spec, or the design / layout is flawed". Technically, there was no "backwards" for years after the 3 prong plug came along because there was no true standard and power transformer primary wires were both identical. Power transformers for many amps have been made with color coded primary wiring for a while now. For example, I know that Mojotone uses a black and a white for 120V windings and Classictone PTs for Marshalls have a series of primary taps for varying amp styles. As I recall, the 120V input uses black and brown twisted together for the hot and brown and white twisted together for the neutral. I don't know if Polytone ever went to color coding for PT primaries. Originally Posted by Tal_175
With the chassis properly grounded, I don't think it matters which way the transformer's primary is connected. There was no way to even identify the hot and netral wires from each other in the old days. Here's the power connection on the original Champ schematic (complete with death cap):
Here's a schematic from a later Polytone with a 3 conductor power cord. The transformer primary wires (shown connecting to the power / polarity switch) are both black and could have been connected either way:
I don't know if the noise you describe is typical of Polytones or of any particular models. If it is not, I have to wonder if yours either has a ground problem or was repaired at some point and the wiring altered or repositioned. Have you checked to be sure that there's a good connection between the ground prong and the chassis? It's possible that the grounding point is discontinuous. If it's 60 Hz hum, it may be common mode hum from signal and power wires running adjacent to each other. If this is typical of Polytones with 3 conductor power cables, it seems like a design flaw.
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If you do have a polarity switch on your amp, wouldn't the wiring be "backwards" in one of the positions of the switch? Originally Posted by nevershouldhavesoldit
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Technically, there is no "backwards" because it doesn't matter which way the primary is wired in those circuits. The primary wires were all the same color and the plug could be inserted either way into the outlet. Reversing the plug had the same effect as throwing the polarity switch, but it didn't matter which wire was hot and which was neutral except as it affected noise and shock hazard. I've never heard any claims of a sonic difference with plug orientation, and I never detected any in my own equipment. My first amp was a Kay 503 I bought new in 1959, after which I went through a series of tube amps with 2 prong plugs - Magnatone, Reverberocket, BF Pro, B15N etc. I've done a lot of solo jazz over the years and have always been very sensitive to amp noise as well as sound quality. Originally Posted by Tal_175
If a point to point amp was designed and built well, the entire signal path (i.e. any wire carrying the audio signal anywhere between the input jack and the speaker wires) was routed well away from any power wires. If that wasn't possible, signal and power wires were crossed as close to 90 degrees to each other as possible, to avoid common mode induction of power line noise. Running a power wire and a signal wire next to each other is bad practice because it can induce noise in the signal. The same is true for the length of signal wires - they should be as short and as well shielded as possible because they're antennae for RFI etc.
I'd love to hear from other Polytone owners with 3 conductor power cords and grounded chassis as to whether they expereince more noise with the polarity switch in one position than the other. It may be endemic to the line, although I'd be surprised if it were since so many great players have used them for solo work over the years.
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Even the noisier polarity isn't noisy enough to be heard during a live performance. It's noisy enough to be noticeable when practicing quietly. I did ask this to my amp tech. He is a very reputable tech in Toronto. When I told him that the amp is noisier in one position than the other, he said "that's what the switch is for.".
I'm not knowledgeable about amp electronics. I just assumed that he was right. But a quick search reveals that there are other people who also claim that:
SoundStage! Synergizing I - Equipment Maximization through Electrical Minimization (06/1997)
From the link above:
"Like everything else in this wonderful world we live in, transformers are not perfect. They inevitably leak small amounts of the current, and the leak is almost always closer to one side of the transformers primary winding than to the other. This carries the chassis closer to the AC lines neutral or hot side, depending on which way the plug is oriented in the wall socket."
The influence of power cables and phase orientation on the sound | HFA - The Independent Source for Audio Equipment Reviews
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I don't know if you want this level of detail, but I'm taking a break from preparing my set list for Thursday night's gig so I thought I'd respond fully. Ignore it if it's too much - I've taken flack here before for providing more info than someone wanted. Originally Posted by Tal_175
The first linked article is an interesting read. The claim that transformers all "leak" some current is true but misleading. Direct leakage to ground is measurably zero in a normal, intact power transformer. There has to be a path through which that current can flow in order for there to be any loss of current from the windings themselves. Unless there is a break in or other damage to the insulation around the winding wire itself, there should be no detectable current flow between a transformer primary winding and ground. Here's a direct quote to that effect from a good article in The Electrical Volt called "Difference between no load, exciting, and leakage current in transformer":
"The leakage current depends on the quality of the insulation. Therefore, the transformer insulation is an important factor for deciding the magnitude of the leakage current. If transformer insulation is in good condition this insulation leakage current should be infinitesimal."
The other two kinds of extraneous current in the title of the EV article I linked do matter: "no load" and "exciting" (which is another way of describing induced current in anything other than the secondary winding where it belongs). These more commonly cause electrical noise and even shock hazard if insulation or a ground connection should fail. There are current flows induced in adjacent conductors by AC current in the transformer windings. Stray capacitances created by conductive elements separated by little enough space to make them a functional capacitor can store and discharge electrical energy. Even the air space between two components on a PCB is a dielectric. Component parts separated by an insulating medium and the primary-to-secondary capacitance of a transformer are common examples of internal structures that can act as capacitors and allow current to flow through them. And all of this can generate noise in an audio amplifier, although it's usually irrelevant in a well designed and built amp.
The concept of "leakage" that causes a grounded chassis to be "closer to the AC lines neutral or hot side" makes no sense at all to me, whether the author means physically closer or electrically, i.e. lower voltage drop between two points. If you measure the voltage between the neutral wire and ground in household electrical circuits, it should be less than 2V. So if your line is at 117 V between hot and neutral, you might measure 116V between hot and ground and 1V between neutral and ground. This is leakage, but it's not from any specific device powered by that line.
The whole idea of power cords that will audibly improve sound quality is a bit specious in my opinion and that of many true authorities (of which I am not one). I'm happy to admit that my failure to understand something does not mean that it's wrong. I do not know everything, and the older I get the more I discover that I didn't even know what I thought I did. But I do own and use a few well reviewed garden hose power cords from reputable manufacturers. I bought them all on clearance sales at tiny fractions of their original prices, just to see what it was all about. I've done controlled testing with them on my best amplifiers - they're currently powering my Prima Luna power amplifier, my Parasound preamp, and assorted DACs and players. The power amp cable is at least an inch thick at its narrowest point, and the connectors are as big as a Bigsby. I've never been able to hear any consistenly definable difference between these and the stock power cords that came with any equipment to which I've connected them.
Based on what I know of physics plus my own experience with dozens of amps over 63 years of playing electric guitar, I personally believe that any difference in noise between polarity switch positions in an intact, well designed amp with properly grounded chassis and 3 conductor power cord reflects physical positioning of the parts within the amp. It's impossible to arrange an amp so that every single piece inside is optimally placed relative to every other piece. Stray induction is inevitable, and shielding will be imperfect. But if that amp is always noisier with the polarity switch in the "normal" position and quieter in "reverse", I'd suspect that something's amiss. And the noise level simply shouldn't be very high in any well functioning amp barring unusual circumstances like a cell tower outside the window, noisy main circuit wiring, etc.
As for whether power line polarity affects the actual sound quality of an amp, it can matter if the power transformer is toroidal because of the placement of the windings and the possibility of stray induction internally. With modern grounded wiring, you want the hot wire to go to both the fusing device and the power switch - this is a standard that is occasionally violated by an enterprising but ill informed builder or repair person. Remember that electrical polarity has nothing to do with the polarity of the speaker. There are many who believe that reversing the speaker leads will alter the sound quality, but I haven't found this to be the case either as long as all drivers are properly phased in relation to each other.
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Hi,
I own that amp, too. It is a great amp, IMO. You _MUST_ keep the distortion and the distortion boost knobs at _full_ counter-clockwise in order to get a true, clean sound. Take some time and exercise the knobs by holding the outer knob while turning the inner knob back and forth. Get some potentiometer cleaner (Cramolin R-5 used to be great for this, but is no longer available) and spray the potentiometers a bit. Then turn the inner knobs some more.
Your amp is almost 40 years old, at this point, so it's possible that without some coaxing the inner knobs won't turn fully off, or that they'll turn back on when you turn the outer knobs clockwise.
Good luck.
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I'm really curious about the noise issue described by Tal_175. Do you have an audible hum in your Polytone? If so, is it affected by the position of the power polarity switch and/or by the volume controls on your guitar and amp? Originally Posted by Greentone
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nevershouldhavesoldit thanks for the detailed info. That's insightful Originally Posted by nevershouldhavesoldit
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Hi Greentone, thanks for your reply. Good to hear from another baby brute owner. That's my initial thought, keeping the Distortion and Dist Boost knobs at zero. But then I don't get any sound. I need to at least turn them past 3 o clock. That's why I'm so confused Originally Posted by Greentone
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Nothing even with the outer volume control turned all the way up?
If that's the case, your amp needs repair is my guess.
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You need to turn the outer knob (Volume) clockwise, while keeping the inner knob (distortion volume) at zero. If it is stuck, then just work the knob back and forth while holding the distortion volume knob stationary at zero. It'll come free. Originally Posted by andreshum
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My amp doesn't hum, but I believe the OPs amp is humming because the distortion volume is stuck in the on position...along with the distortion boost. Once he gets them freed up and can set them at zero he will be okay. Originally Posted by nevershouldhavesoldit
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Thx! That sounds like a very reasonable explanation. Originally Posted by Greentone
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I'm willing to accept that the hum reduction effect of the reverse switch in my amp is a coincidence and my amp has an independent noise problem. But it seems like the company made a point of adding the reverse switch to their amps for 10-15 years. I wonder what it was intended for then?
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It was a common “feature” for many years and was expected. And many people used “cheater” adapters to,plug into 2 prong (ie ungrounded) outlets for years after the 3 conductor power cord became standard. So reverse electrical polarity was still possible until all outlets were 3 prong. Originally Posted by Tal_175
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