ok i have a serious question in regards to an issue i have seen in regards to PT wiring on a 5E3 style amp circuit and seek some advice. ok the pt i am going to use is a Pt2L that i got off of fleabay which has a ct hv ( red, red, red/yellow stripe) and ct 6.3 and the wiring diagrams are ALMOST all the same with one exception and that is some of the 5E3 diagrams i have seen show the red/yellow ct wire conected to ground while others show it connected to the turret board so i am wondering which is correct ( if either) with this pt? OR do i just cap off the red/yellow striped wire. first amp build ( although i have made a couple guitars 😛) and i chose the 5E3 for simplicity before going big with a marshall style amp but this discrepency is confusing me and i really need some help because i have been unable to find any web info on the old midwest coil and transformer PT2L and only know the seller i got it from on fleabay said it was used with 2x 6v6, 3x 12AX7 and a 5y3GT.
my plan is to run 5y3GT, 2x 6v6GT, and 2x 12AX7 ( i was also trying out a 12AY7 in place of the first preamp tube eventually but chances are i would most likely stick with the 2x 12AX7 because i have a pair of vintage conn/sylvania 12AX7 tubes 😛 .
any assist in wiring the PT would be greatly appreciated.
here is a link to the PT:
VINTAGE TUBE AMP POWER TRANSFORMER #240
my plan is to run 5y3GT, 2x 6v6GT, and 2x 12AX7 ( i was also trying out a 12AY7 in place of the first preamp tube eventually but chances are i would most likely stick with the 2x 12AX7 because i have a pair of vintage conn/sylvania 12AX7 tubes 😛 .
any assist in wiring the PT would be greatly appreciated.
here is a link to the PT:
VINTAGE TUBE AMP POWER TRANSFORMER #240
By 'wiring diagrams', it sounds like you are referring to layout diagrams which show drawings of the components. Have you looked at the schematic diagram(s) for the 5E3 amp?
I think that all the common Fender amps with tube rectifiers used a full-wave rectifier with grounded center tap.
If you could attach copies of the diagrams that are causing the confusion, I'm sure somebody here would be glad to help.
I looked at the ebay ad, and there should be enough info for you to use that transformer - the HV secondary is 350-0-350, which is about the same as the transformers sold for 5E3 amps.
I think that all the common Fender amps with tube rectifiers used a full-wave rectifier with grounded center tap.
If you could attach copies of the diagrams that are causing the confusion, I'm sure somebody here would be glad to help.
I looked at the ebay ad, and there should be enough info for you to use that transformer - the HV secondary is 350-0-350, which is about the same as the transformers sold for 5E3 amps.
http://img.docstoccdn.com/thumb/orig/93283822.png
and
http://music-electronics-forum.com/attachments/2606d1213308377-new_tweedy_5e3_layout.gif
here is one with hv ct running to B+ fuse and using 2 fuses and one switch:
http://www.uraltone.com/infoen/wp-content/uploads/2014/02/5e3_layout_v121.jpg
but if i understand you correctly if i want to use one of these 2 layouts:
http://img.docstoccdn.com/thumb/orig/93283822.png
or
https://d1sjrnpi226dnf.cloudfront.net/spree/attached_files/tweed5e3_wiring_layout.pdf?1400188816
then i would ground the red/yellow striped wire on the PT correct.
and
http://music-electronics-forum.com/attachments/2606d1213308377-new_tweedy_5e3_layout.gif
here is one with hv ct running to B+ fuse and using 2 fuses and one switch:
http://www.uraltone.com/infoen/wp-content/uploads/2014/02/5e3_layout_v121.jpg
but if i understand you correctly if i want to use one of these 2 layouts:
http://img.docstoccdn.com/thumb/orig/93283822.png
or
https://d1sjrnpi226dnf.cloudfront.net/spree/attached_files/tweed5e3_wiring_layout.pdf?1400188816
then i would ground the red/yellow striped wire on the PT correct.
Moved to I&A forum.
wow! looks like a power transformer is now an instrument or amp., when did this change happen?
No hard and fast rules 🙂 but a 5E3 amp fits the I&A profile and there is more talk of valves and 'Marshall' than of power transformers.
You'll probably get more help here than in the power supply section.
You'll probably get more help here than in the power supply section.
ok so from now on when i have a question about the proper connection of a power transformer i put it in the musical I&A section. ok it is all good. with that said i have a bunch of these new rare pt "I&A" i will sell and apparently they are so new and rare they are priceless but hey im willing to deal 😛
No matter which layout you use, the PT CT (red/yellow) is grounded. Looking at the schematic will make this clear.
The layouts differ (and only slightly) only in where the CT is grounded.
ok thanks, it was really confusing because on one that i saw the ct goes to a fuse and that fuse then goes to the turret board which i found odd.
Hi Lord, welcome here.
The 5E3 is a guitar amp, that is why they moved it to the instrument amp section. Your questions were specifically about the layout of the guitar amp application of that transformer. if you were building a stereo amp for your home hifi with it, they would have left it in some other section. The needs of guitar amps are very different from those of hifi amps.
One thing to keep in mind is that it is always about the circuit rather than the parts. You did initially say "5E3 style" amp, so we can't hold you to the official 5E3 schematic from fender.
The center tap of the high voltage winding is to be grounded. WHERE to ground it is a choice. Wire the CT to a grounded terminal on the eyelet board instead of direct to chassis, and it still is grounded. Arguments are made as to which is "better" but should be taken in the overall context.
Fender never fused the high voltage leads, but many people prefer to do so. In the center tap lead to ground is a good place to do it with a single fuse. Some people prefer to ground the CT and fuse each red wire. Your choice.
usually we prefer to ground the CT right to the negative end of the main reservoir cap. In amps with a can cap soldered to chassis, we ground it to one of the grounding tabs around the cap. In your initial layout, the reservoir was on the eyelet board, so they soldered the CT there, and ran a wire to chassis from that point. The idea is to keep the return path from that main cap as short as possible so other points in the circuit do not share a copper path with that return. This for hum abatement.
The 5E3 is a guitar amp, that is why they moved it to the instrument amp section. Your questions were specifically about the layout of the guitar amp application of that transformer. if you were building a stereo amp for your home hifi with it, they would have left it in some other section. The needs of guitar amps are very different from those of hifi amps.
One thing to keep in mind is that it is always about the circuit rather than the parts. You did initially say "5E3 style" amp, so we can't hold you to the official 5E3 schematic from fender.
The center tap of the high voltage winding is to be grounded. WHERE to ground it is a choice. Wire the CT to a grounded terminal on the eyelet board instead of direct to chassis, and it still is grounded. Arguments are made as to which is "better" but should be taken in the overall context.
Fender never fused the high voltage leads, but many people prefer to do so. In the center tap lead to ground is a good place to do it with a single fuse. Some people prefer to ground the CT and fuse each red wire. Your choice.
usually we prefer to ground the CT right to the negative end of the main reservoir cap. In amps with a can cap soldered to chassis, we ground it to one of the grounding tabs around the cap. In your initial layout, the reservoir was on the eyelet board, so they soldered the CT there, and ran a wire to chassis from that point. The idea is to keep the return path from that main cap as short as possible so other points in the circuit do not share a copper path with that return. This for hum abatement.
ok thanks enzo, i will ground it on the same lug as the ct for the 6.3v since that seems to be where the majority of different schems for 5e3 style amps seem to be grounded. this also helps make it simpler in regars to keeping the wiring as clean as possible.
hi there yes it goes to ground, but you can put it thru a switch so it acts as standby kills all the ht but leaves the heaters live.
the schems i am looking at have standby switches as part of the circuit with the hv ct grounded.
one thing i am now looking at is if i will need to make any changes to the circuit because i am wanting to run 2x 12AX7 tubes ( since i have a pair of NOS conn/sylvania 12AX7's) instead of a 12AX7 and a 12AY7 that the scem shows or do i just pop in the 2x 12AX7's with no changes to the circuit.
Just Google "5e3 12ax7 instead of 12ay7" and read all the opinions. 🙂
I'd keep to the original 5E3 schematic - then if you aren't happy with the 12AX7 in V1 you can easily change to the original 5E3 spec. with a simple tube swap.
Imagine you have a battery wired to a light bulb. A wire from each end of the battery to one end of the bulb each. A simple loop circuit. It doesn't matter which end of the battery you disconnect to turn off the bulb. Just so electrically with standby switches. You can break the center tap ground lead to turn off the voltage, or you can break the two hot leads to turn off the voltage, or you can go Fender and put the break switch after the rectifier. There are cases to be made for preferring one or another, but all those will work. These are just guitar amps, not high tech critical circuits. And in the case of the 5E3, it doesn't need a standby switch anyway, which is why ther is no standby switch on the Fender schematic.
sorry Enzo for once i have to disagree, can't put up with all that hum (mine is heavally moded fopr harp way more gain)when not playing, it may not be that loud, but.. and may only need harp in 2 song's per set. don't like just switching off hot valves, so for me standby is a must.
as for the 12ax7 it works fine in both slots just a bit more gain and maybe a bit of pre amp distrotion if wound right up and maybe a bit more hiss when not playing. it won't damage the amp so go ahead and try it out, it may alter tone see if you like it, if not put the 12ay7 back in😀
i dont even have a 12AY7 LOL, as far as distortion goes that is my preference anyway. the only reason for the 5e3 style amp is due to having the tranny for one and it was a simple first build, eventually i want to build a marshall style 😀
Arctic, you may have a practical desire for a mute switch, but the amp circuit does not need one for safe reliable operation. If your mic makes noise while not in use, a standby switch would work, sure, but so would a mute switch on the mic itself, or just spin the volume control on the amp or the mic to zero. The OP was concerned with power supply wiring, so my point was in response to that concern. if he wants a standby, by all means add one, it just isn't an electrical necessity.
curious as to if it isnt needed why there are a lot of schems and diagrams which show one including a couple i ran across ( but cant seem to find now) from fender.
It isn't NEEDED because most amps do not need them, especially low power amps like this one. In my view people are overly concerned with concepts they read about but that are not really applicable to small circuits like this. This like cathode poisoning and cathode stripping. They just don't occur in a pair of 6V6s running on 300-400v.
Peavey made the VERY popular Classic 30 for 20 years, it had no standby switch. They in recent years issued the Classic 30 version II, they added a standby switch simply because amp buyers EXPECT them. I have seen guys wanting to add a standby switch to a little Fender Champ, just because "it ought to have one". There is such an entrenched idea that all amps must have them that amp makers now include them regardless. For the small price of the added switch, they lose X fewer sales to people who think amps are deficient without.
And whether they think it needs one or not, there are plenty of people who WANT one anyway, like Artic here, he has a very good reason for wanting one, it just hasn't anything to do with the power tubes.
Your 5E3 Deluxe lacks a standby, while the later AB763 Deluxe does have one. There are zillions of Fenders with the switch, and many without. When it comes to clones, the people designing the clones are free to add the switch either for marketing reasons or just because they feel it needs one.
Peavey made the VERY popular Classic 30 for 20 years, it had no standby switch. They in recent years issued the Classic 30 version II, they added a standby switch simply because amp buyers EXPECT them. I have seen guys wanting to add a standby switch to a little Fender Champ, just because "it ought to have one". There is such an entrenched idea that all amps must have them that amp makers now include them regardless. For the small price of the added switch, they lose X fewer sales to people who think amps are deficient without.
And whether they think it needs one or not, there are plenty of people who WANT one anyway, like Artic here, he has a very good reason for wanting one, it just hasn't anything to do with the power tubes.
Your 5E3 Deluxe lacks a standby, while the later AB763 Deluxe does have one. There are zillions of Fenders with the switch, and many without. When it comes to clones, the people designing the clones are free to add the switch either for marketing reasons or just because they feel it needs one.
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