xxJPMxx Posted November 12, 2015 Share Posted November 12, 2015 (edited) The standby switch is pointless unless the power supply caps are not rated for the higher no load voltage condition, other than that these voltages are not high enough to produce cathode stripping. Also most people use electrolytic capacitors which have a high dielectric absorption so instead of the caps bleeding off on their own they actually do quite the opposite. That power transformer's high voltage secondary winding is rated for something like 4x the current you are using it for, I hardly doubt it will notice the 1mA of extra current draw a 330k bleed resistor will add. I don't mind helping with the remote control power supply, let me know it's power requirements and I will do my best to assist you. Edited November 12, 2015 by xxJPMxx 1 Quote Link to comment Share on other sites More sharing options...
ToolShedAmps Posted November 12, 2015 Author Share Posted November 12, 2015 The standby switch is pointless unless the power supply caps are not rated for the higher no load voltage condition, other than that these voltages are not high enough to produce cathode stripping. Also most people use electrolytic capacitors which have a high dielectric absorption so instead of the caps bleeding off on their own they actually do quite the opposite. That power transformer's high voltage secondary winding is rated for something like 4x the current you are using it for, I hardly doubt it will notice the 1mA of extra current draw a 330k bleed resistor will add. I don't mind helping with the remote control power supply, let me know it's power requirements and I will do my best to assist you. Excellent! Let it be known that I don't want to be considered "un-coach-able", we will add the 330K Bleed-Down Resistor to the schematic. However, we will still maintain the "Standby" switch for those of us who prefer to leave our Line-Stages "Cookin' and Ready to Roll" at a moments notice. Thanks again, Matt. Quote Link to comment Share on other sites More sharing options...
ToolShedAmps Posted November 12, 2015 Author Share Posted November 12, 2015 The voltage output of the Hammond power xfmrs tends to run fairly high, especially if wired for 115V. I recommend using the 125V primary of the 269JX in any situation where the line voltage is above 117 or so. Even doing that, the 6J5 filaments are likely to be presented with over 7V necessitating a higher value dropping resistor than JP suggested above. Same for the rectifier filament xfmr which has a primary designed for 115-117V- voltage will have to be dropped for that tube as well. The resistors should be installed in a way which allows the generated heat to escape. I'm not a fan of heat build-up under the chassis. And, as JP pointed out, a bleeder should absolutely be installed for safety. The 6J5s are not going to draw enough current to allow for even a moderate bleed as their cathodes cool off. Maynard Hi Maynard, Thanks so much for pointing out the 5v transformer is rated at 115v at input as well. This is a great catch, perhaps what we should do is focus our attention on dropping the voltage on the 5v tranny and switch to the 379JX (although it's a bit more money) on the PT for the reason stated by JPM and so that we aren't bothered by that nasty electro-mechanical buzzing that single-primary Hammonds are known for. Great, this ought to work well then. Thanks again, Matt. Quote Link to comment Share on other sites More sharing options...
xxJPMxx Posted November 12, 2015 Share Posted November 12, 2015 I fear the standby switch might cause a popping sound through the power amp. It could be easy to add a 555 timer and a relay to mute the outputs until things are warmed up but that's probably overkill. Or the easiest route is switch to an indirectly heated tube rectifier so things ramp up slowly. Sorry I know I am a pain in the butt Switching to the 300 series might be easier but sticking with what you have isn't too tought to work the bugs out, I know Maynard uses the 200 series all the time, he is a wealth of knowledge and won't mind helping I don't think. The 83 pulls 3A and the 80 pulls 2A, I say pick one and design specifcally for that because with the type 80 and the 115 primary you will be way over the 5v. Quote Link to comment Share on other sites More sharing options...
tube fanatic Posted November 12, 2015 Share Posted November 12, 2015 Matt, have you considered simplifying things and using something like a 270CAX or 270X which have a 5V/2A winding and the dual primary voltage options? That would be less costly than using the 269JX and additional filament xfmr for the rectifier. As far as a standby function goes, you could put around a 47k resistor between the high voltage CT and ground with a switch across it, or put one between the rectifier and input cap. That would keep the caps somewhat charged and should eliminate any concerns about popping when going in or out of standby. If it were my decision, I'd forget about a standby switch altogether. The 6J5s are running well below their rated plate dissipation and should, with controlled filament voltage, last "forever" anyway even if never turned off. Maynard Quote Link to comment Share on other sites More sharing options...
ToolShedAmps Posted November 12, 2015 Author Share Posted November 12, 2015 (edited) I fear the standby switch might cause a popping sound through the power amp. It could be easy to add a 555 timer and a relay to mute the outputs until things are warmed up but that's probably overkill. Or the easiest route is switch to an indirectly heated tube rectifier so things ramp up slowly. Sorry I know I am a pain in the butt Switching to the 300 series might be easier but sticking with what you have isn't too tought to work the bugs out, I know Maynard uses the 200 series all the time, he is a wealth of knowledge and won't mind helping I don't think. The 83 pulls 3A and the 80 pulls 2A, I say pick one and design specifcally for that because with the type 80 and the 115 primary you will be way over the 5v. Matt, have you considered simplifying things and using something like a 270CAX or 270X which have a 5V/2A winding and the dual primary voltage options? That would be less costly than using the 269JX and additional filament xfmr for the rectifier. As far as a standby function goes, you could put around a 47k resistor between the high voltage CT and ground with a switch across it, or put one between the rectifier and input cap. That would keep the caps somewhat charged and should eliminate any concerns about popping when going in or out of standby. If it were my decision, I'd forget about a standby switch altogether. The 6J5s are running well below their rated plate dissipation and should, with controlled filament voltage, last "forever" anyway even if never turned off. Maynard Hi Maynard, Yes, I have considered using the 200 Series (as evidenced by this initial PS design), however, although it would alleviate the need for the 5v tranny (but not really unless the design is limited to the 80 Rec) it still has the non-dual primary problem (what I mean is, "actual separate windings that are either put in parallel for 120v or series for 240v input) these are the only Hammonds that I know for sure don't "Buzz". Like I said, I normally either use the 300 Series or (with enough lead-time) the dual-primary Edcor's. Also, to clarify, you are suggesting a 47K resistor in "series" with the standby switch to ground? Or, "Parallel" with the switch to ground? As for limiting the rectifier choice, I think it would be pretty "neat" if we could figure it out using the 5v filament tranny, I'm guessing as it is only 5v @ either 2 or 3A, a nice Carling DPDT ought to be able to switch in the required dropping resistor for each? So if one of you has the ability to run a sim with that 115v input rating (assuming MOST of us actually have 118v at the wall) the value of the dropping resistors could be realized. I think that the extra $15 or so in parts would be worth the ability to "show off" a Merc and shift the O.P. (If JPM would be so kind to run the distortion sim again with the 320v supply voltage we should see a difference in the distortion plot, all other things being equal). I will change the Power Transformer to the Hammond 369JX, as it has the "real" dual-primaries and it is less than $20 more than the 200 Series PT in the original schematic. Thanks gents, Matt. Edited November 12, 2015 by ToolShedAmps Quote Link to comment Share on other sites More sharing options...
xxJPMxx Posted November 12, 2015 Share Posted November 12, 2015 ....really isn't necessary when you run get yourself another beer (or get rid of the one you just had...... Hold the phone here did someone mention beer? I think I will have a Troeg's Perpetual IPA right about now. I usually reserve my beer drinking night for Wednesday at band practice but I skipped out last night because my stooopid back is killing me. Yeah I know I am a wimp. So here I am drinking while my better half is at work (I feel no guilt). Back to your amp. The filament transformer might be a bit tricky to do from paper since I can't find published winding resistance specs. I could extrapolate it from load data but I need two data points to calculate. So where we stand is if you use the type 83 you know that w/ the primary voltage @ 120 your heater voltage will be 5.2V, no big deal if you ask me. How high will it get with the type 80? That's the million dollar question I guess. The 5U4 pulls 3A, maybe use that instead of the type 80? 1 Quote Link to comment Share on other sites More sharing options...
ToolShedAmps Posted November 12, 2015 Author Share Posted November 12, 2015 ....really isn't necessary when you run get yourself another beer (or get rid of the one you just had...... Hold the phone here did someone mention beer? I think I will have a Troeg's Perpetual IPA right about now. I usually reserve my beer drinking night for Wednesday at band practice but I skipped out last night because my stooopid back is killing me. Yeah I know I am a wimp. So here I am drinking while my better half is at work (I feel no guilt). Back to your amp. The filament transformer might be a bit tricky to do from paper since I can't find published winding resistance specs. I could extrapolate it from load data but I need two data points to calculate. So where we stand is if you use the type 83 you know that w/ the primary voltage @ 120 your heater voltage will be 5.2V, no big deal if you ask me. How high will it get with the type 80? That's the million dollar question I guess. The 5U4 pulls 3A, maybe use that instead of the type 80? Unfortunately we can't use the 5U4G, it uses the standard Octal base while the 80 and 83 share the same pin-out on the UX-4 base. I think honestly, part of the "fun" of this Line-Stage is that guys (even the ones with SS amps and have never owned a "tube" anything) will get the chance to play with valves that are literally "a Gas". Come-on, you know that running a Mercury Vape or a "huge" Globe gits' you grinning every time you look at it. Mo' beers = mo' grins! 1 Quote Link to comment Share on other sites More sharing options...
xxJPMxx Posted November 12, 2015 Share Posted November 12, 2015 (edited) Yes sir gas rectifiers look cool for sure! The 83 rectifier is a pretty heavy duty rectifier. It will only drop 15 volts no matter the load up until the point of saturation. My opinion is it's kind of overkill and inefficient for the application. Since you aren't building guitar amps and compression from sag isn't a design goal, and still it's class A so no sag anyway. The only other reasons for tube rectification is slow B+ ramp up which isn't going to happen with directly heated rectifiers, that leaves noise. SS rectifier noise can be mitigated by the use of fast diodes and or snubber networks across them, I like UF4007's. You can then use two OD3 gas regulator tubes in series to regulate the B+, you still get the cool gas tube look but they are also functional, unlike a directly heated rectifier tube for a preamp Or have your cake and eat it too, go with a transformer with a 5V 2A winding and use an indirectly heated tube for slow B+ ramp up and then use the gas regulator tubes for looks and regulation. You need to shunt the regulators with a small value cap, 100nF max I believe. Just my 2 pennies. This is your build, I just like to help give options. Edited November 12, 2015 by xxJPMxx Quote Link to comment Share on other sites More sharing options...
mikebse2a3 Posted November 13, 2015 Share Posted November 13, 2015 So if one of you has the ability to run a sim with that 115v input rating (assuming MOST of us actually have 118v at the wall) The power company is allowed to run 114v to 126v (ie: +/-5%). It is very common to see 120v to 124v at the wall in my area. miketn Quote Link to comment Share on other sites More sharing options...
ToolShedAmps Posted November 13, 2015 Author Share Posted November 13, 2015 So if one of you has the ability to run a sim with that 115v input rating (assuming MOST of us actually have 118v at the wall) The power company is allowed to run 114v to 126v (ie: +/-5%). It is very common to see 120v to 124v at the wall in my area. miketn Wow, thanks for the info....now THAT must really play havok with all of the excellent vintage guitar amps in your area! Or ANY old power transformer for that matter. Quote Link to comment Share on other sites More sharing options...
ToolShedAmps Posted November 13, 2015 Author Share Posted November 13, 2015 Yes sir gas rectifiers look cool for sure! The 83 rectifier is a pretty heavy duty rectifier. It will only drop 15 volts no matter the load up until the point of saturation. My opinion is it's kind of overkill and inefficient for the application. Since you aren't building guitar amps and compression from sag isn't a design goal, and still it's class A so no sag anyway. The only other reasons for tube rectification is slow B+ ramp up which isn't going to happen with directly heated rectifiers, that leaves noise. SS rectifier noise can be mitigated by the use of fast diodes and or snubber networks across them, I like UF4007's. You can then use two OD3 gas regulator tubes in series to regulate the B+, you still get the cool gas tube look but they are also functional, unlike a directly heated rectifier tube for a preamp Or have your cake and eat it too, go with a transformer with a 5V 2A winding and use an indirectly heated tube for slow B+ ramp up and then use the gas regulator tubes for looks and regulation. You need to shunt the regulators with a small value cap, 100nF max I believe. Just my 2 pennies. This is your build, I just like to help give options. Ahh....I don't believe in efficiency anyway, if I did I'd probably start designing CCS loaded transistors with FET followers, or something.... I'll just do it the empirical way, I'll build the PS and the circuit, load it, then use my variac at several voltages from 118v to 125v with each rectifier, find the "best" average voltage drop with each Rec., and let everyone know. This solution will then also allow for individuals at the extreme ends of the scale to adjust accordingly. Sound good? Thanks, Matt. Quote Link to comment Share on other sites More sharing options...
xxJPMxx Posted November 13, 2015 Share Posted November 13, 2015 Yeah I am the last person that should bring up efficiency. I guess what I should have said is I would save the type 83 for a high powered class AB power amp. But they do look pretty cool, I wish my Hickok tube tester had it on the exterior so I could look at it while testing tubes. 1 Quote Link to comment Share on other sites More sharing options...
ToolShedAmps Posted November 13, 2015 Author Share Posted November 13, 2015 Yeah I am the last person that should bring up efficiency. I guess what I should have said is I would save the type 83 for a high powered class AB power amp. But they do look pretty cool, I wish my Hickok tube tester had it on the exterior so I could look at it while testing tubes. I think it's best attribute is the 15v drop. You can design excellent "choke" loaded power supplies with it and get away with using a minuscule input cap as a "shock absorber" to be able to use open-frame chokes. It really is a wonderful piece of equipment. In the case of using it at max current and high voltage, you would normally have to use 2X 5U4G's Paralleled to do the same thing. I have on my drawing board the design for Mono-blocs based on my Transcendence12 stereo amp that uses paralleled KT-160's, theoretically, output is in the neighborhood of 32 watts single-ended that uses the 83. Quote Link to comment Share on other sites More sharing options...
xxJPMxx Posted November 13, 2015 Share Posted November 13, 2015 KT120? I have never seen a KT160. If you like tube aesthetics I recommend checking out the gas regulators. I have changed my mind on my latest build about a million times and I finally have decided on using gas regulators in an over the top external power supply. That purple glow is intoxicating! 1 Quote Link to comment Share on other sites More sharing options...
ToolShedAmps Posted November 13, 2015 Author Share Posted November 13, 2015 KT120? I have never seen a KT160. If you like tube aesthetics I recommend checking out the gas regulators. I have changed my mind on my latest build about a million times and I finally have decided on using gas regulators in an over the top external power supply. That purple glow is intoxicating! Sorry, Type-o, KT-150, here is the data sheet. KT150 Tung-Sol TubeDataSheet.pdf Quote Link to comment Share on other sites More sharing options...
cfishbowl Posted November 13, 2015 Share Posted November 13, 2015 Matt, you mentioned Edcor earlier. For those of us partial to their transformers, would something like the xpwr001 be a good choice? Seems like this would be a way to run the hv, the rectifier filament, and the filament for the preamp tubes all with one transformer. And it's 46 bucks. Thoughts? Sent from my iPhone using Tapatalk 1 Quote Link to comment Share on other sites More sharing options...
ToolShedAmps Posted November 13, 2015 Author Share Posted November 13, 2015 Matt, you mentioned Edcor earlier. For those of us partial to their transformers, would something like the xpwr001 be a good choice? Seems like this would be a way to run the hv, the rectifier filament, and the filament for the preamp tubes all with one transformer. And it's 46 bucks. Thoughts? Sent from my iPhone using Tapatalk Good Morning Corey I will state this for the benefit of all. I PREFER to use Edcor POWER transformers because they can be ordered with a 120v input rating primary. This alleviates the need for dropping resistors on the filaments (unless you, like me, intentionally like to run small-signal tubes "slightly" starved.) However, as 90%+ of my sales are "custom" amplifiers, the lead-time from Edcor (which can be as much as 8-weeks) generally prohibits their use as my customers rarely want to wait that long. I will be revising the PS schematic at some point this weekend to reflect the changes that forum members; Maynard, xxJPMxx, and myself have worked through. As part of these PS changes, I will note which Hammond part #'s to order, as well as (for those of you who can wait) the preferred Edcor part #'s.] Corey, to answer your question, the XPWR001 @ $46 "could" be used IF you limit your rectifier choice to the 80. In my estimation, most members (whether DIY'ers or purchasers) would LOVE the option of a Mercury Vapor rectifier (83), I would recommend instead the XPWR136 @ $32, select the "dual-primary" option for another $5, and add the $20 LVP5-3-120 (5v/3A filament Tranny) to your order for a total of $57 So, for a cost difference of less than the price of a decent burger and fries you have the option of running the Merc Matt. Quote Link to comment Share on other sites More sharing options...
cfishbowl Posted November 13, 2015 Share Posted November 13, 2015 Sweet. Thanks Matt! I live in Portland, or so it better be a free range, organically and ethically sourced humanely prepared burger and fries with artisanal ketchup. [emoji23] Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
spendorite Posted February 29, 2016 Share Posted February 29, 2016 [ I will be revising the PS schematic at some point this weekend to reflect the changes that forum members; Maynard, xxJPMxx, and myself have worked through. As part of these PS changes, I will note which Hammond part #'s to order, as well as (for those of you who can wait) the preferred Edcor part #'s.] Any further updates on the power supply schematic ? Quote Link to comment Share on other sites More sharing options...
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