Vox ac15tb > ok with a 16ohm spkr?

[vintagekiki]

In terms load (PT and power tubes), if power brake (dummy load) instead speaker connected to OT, behaves the same as the speaker connected to OT.
If the amplifier is set to 12, and the dummy load set to room power 0.5W (neighbors sleep peacefully) OT and power tubes behave as the amplifier set to 12 with speakers.

[Chuck H]

Hi there Chuck- only recently saw these posts of yours.. really appreciated. I did in fact build a simple attenuator version, i think it might resemble your 2nd post affair, but I found it only 1/2 useable.. I'm not entirely sure why, but seems to work only mediocre at best so it's left unused. I'd love to try building the 'better' version, but alas I cannot re-interpret schematics into physical layouts, I'm just not that advanced. I dont suppose you had an inside pic of your creation?

thanks alot for these- it's food for thought.

Well here's a diagram. Good for 8 ohms at 50W. You can lay it out however you want, really. But it's best to give the resistors a little room and keep the capacitor as far from that 10r/50w resistor as practical. Like I said before, use an aluminum chassis and mount the resistors with thermal paste.

Also, sometimes 50W chassis mount resistors are disproportionately expensive. You can replace the 10r/50w with two 20r/25w in parallel (as shown in the earlier schematic) if you want to.

Also, also... Just use the inductors I linked earlier (or equivalent). Regarding the "inductor sandwich", that's two .25mH inductors wired in series and out of phase with a copper plate in between. You'll know if you have them in phase or out of phase because in phase will whistle with single coil pickups and out pf phase will not So build it such that you can disassemble it in case it comes to that.

[pdf64]

Does running the amp flat out put as much strain on the PT, as I know it does the tubes?...

The output valves are under more stress when the amp is running flat out because they're conducting more current, that current is being supplied by the PT.

[Sea Chief]

Well here's a diagram. Good for 8 ohms at 50W. You can lay it out however you want, really. But it's best to give the resistors a little room and keep the capacitor as far from that 10r/50w resistor as practical. Like I said before, use an aluminum chassis and mount the resistors with thermal paste.

Also, sometimes 50W chassis mount resistors are disproportionately expensive. You can replace the 10r/50w with two 20r/25w in parallel (as shown in the earlier schematic) if you want to.

Also, also... Just use the inductors I linked earlier (or equivalent). Regarding the "inductor sandwich", that's two .25mH inductors wired in series and out of phase with a copper plate in between. You'll know if you have them in phase or out of phase because in phase will whistle with single coil pickups and out pf phase will not So build it such that you can disassemble it in case it comes to that.

Hi Chuck, yes thanks for this again.. but I just cannot interpret schematics into physical layouts. For eg, I have no idea for a start what size this schematic/ device would phyically be, if things need space from others, how you could interpret the components into physical proximities one to the next. Unless i can see how they manifest into something tangeable, i just cannot see how to even start.

schematics are a language that i find extremely difficult & does not come naturally. You for eg, could maybe see this schematic if shown it for the 1 st time, & naturally perhaps picture the physical interpretation, in order to proceed. I cannot.

[Chuck H]

Well I know from previous interactions that this may not work, but here goes...

The "diagram" above is a demonstration of the components in relative physical size/appearance and only (somewhat) schematic like, in that it's laid out for clarity of what is connected to what. And I can't imagine making it simpler. A drawing of any physical layout of what would be a "finished unit" would likely make the connections impossible to interpret. This is what diagrams are for.

You know, for example, that the rheostat, jacks and switch need to go through holes in whatever chassis you use. And you know (because I mentioned it) that you should locate the capacitor away from the resistors as much as practical. And you know (because I mentioned it) that the resistors are chassis mount and should be screwed to the aluminum surface using thermal paste.

And I assume you you get that the parts go inside the box rather than outside

Parts are parts. You can arrange them for convenience of use for jacks and knobs and inside for economy of arrangement.

Which image below better demonstrates how to wire a lamp?

[vintagekiki]

I just cannot interpret schematics ... schematics are a language that i find extremely difficult & does not come naturally ... I cannot.

Be persistent, you can do it. I'm sure that you can.
Just remember how you full of yourself recently wrote ...

About Reactive Load
https://www.freestompboxes.org/viewtopic.php?f=2&t=30764

[Sea Chief]

Chuck H sorry I thought the diagram you put up -was- another schematic. I mean it is.. isn't it-? Im not quite understanding the lamp question! I think you are intending to humour me, but without there being any visible wire in the 2nd lamp diagram, I can't see how the question makes any sense-!

Anyway I did understand you said to put A away from B. But still I cannot visualise the physical size of such a contraption, because I am not familiar with some components,. an inductor.. might be huge or tiddly. Ive seen one in a speaker about an inch high iirc.. but should I assume yours here might be similar size then, or maybe its the size of a Buick..

[vintagekiki]

https://music-electronics-forum.com/forum/amplification/guitar-amps/maintenance-troubleshooting-repair/927656-vox-ac15tb-ok-with-a-16ohm-spkr?p=927700#post927700

[Sea Chief]

https://music-electronics-forum.com/forum/amplification/guitar-amps/maintenance-troubleshooting-repair/927656-vox-ac15tb-ok-with-a-16ohm-spkr?p=927700#post927700

Vkk as usual I appreciate you are mostly trying to help, but unfortunately I can never understand what you mean in almost every thing you post.. especially if its a bit peculiar like this link.. to this very thread. I'm left bewildered as usual. maybe this is your main intent I'm not sure.

[Chuck H]

...or maybe its the size of a Buick..

Haha! Ok, the 12mH inductor size is a bit fudged in the diagram just so it would fit in the drawing. It's probably twice that size and weighs about a pound. So yes, not the size of a Buick, but large. EVERYTHING ELSE though is proportionately represented.

Honestly, If you ordered a 7"x5"x3" Hammond aluminum enclosure and the parts indicated, then chose where you wanted your jacks, knob and switch to be you would see pretty easily where the other parts would need to go. And because of the diagram you'd know what connects to what.

I'll try (later) to draw up a layout diagram. Since I can't work in three dimensions that way the chassis may be a little larger, but that won't hurt anything.

[Sea Chief]

Haha! Ok, the 12mH inductor size is a bit fudged in the diagram just so it would fit in the drawing. It's probably twice that size and weighs about a pound. So yes, not the size of a Buick, but large. EVERYTHING ELSE though is proportionately represented.

Honestly, If you ordered a 7"x5"x3" Hammond aluminum enclosure and the parts indicated, then chose where you wanted your jacks, knob and switch to be you would see pretty easily where the other parts would need to go. And because of the diagram you'd know what connects to what.

I'll try (later) to draw up a layout diagram. Since I can't work in three dimensions that way the chassis may be a little larger, but that won't hurt anything.

Ok great having that chassis mentioned is the start i need. You could pm me any pic if preferable.. be grateful to see anything giving me more 'help the idiot' understandings. Thanks sc

[Sea Chief]

Chuck, if I need such a big enclosure & I know hammond alu ones are good quality.. I cannot tho for love nor money find a 7x5x5 one. trawled the www (maybe not made anymore?.) Can you recall any part number?

[vintagekiki]

or maybe its the size of a Buick..

I misunderstood #69. Thought refer to Buick as a machine (car)

when it Buick refers to the Buick coil.
Sorry

[Sea Chief]

I misunderstood #69. Thought refer to Buick as a machine (car)

when it Buick refers to the Buick coil.
Sorry

no.. it did refer to a car vkk!

[Chuck H]

Chuck, if I need such a big enclosure & I know hammond alu ones are good quality.. I cannot tho for love nor money find a 7x5x5 one. trawled the www (maybe not made anymore?.) Can you recall any part number?

Maybe because I wrote 7"x5"x3".

Here it is at Parts Express. The same site I linked for the inductors. Not sure if that helps you in your location (shipping?).

https://www.parts-express.com/Hammon...y-Case-320-780