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Sorry guys, in my haste, I somehow managed to delete posts in both places. So, we'll have to start up a VRM thread again.


viewtopic.php?t=1176

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Soooo, why would I want to put a VRM in my 5E3????? What'll it give me that I currently don't have, and what will I lose by installing it?

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Peace,

Paul

Install a VRM if you want to get essentially the same sound as when you crank it, but at a lower overall volume - or maybe when you practice at 2AM in the morning!

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Hey everyone.

Finished installation of the VRM (Vroom) circuit in my TC-15 last night.

There wasn't a lot of space to put the board, so I was fairly limited where I could fit this. I drilled a hole in the chassis, put on some heat sink goo, then the mica insulator, more goo and mounted the board.



Again, apologies to coco and all you neat builders out there I hope to improve with experience. Since coco recommended having the wires as close to the pot as possible, I didn't waste any length routing the wiring around to make it neat. Also, while I have two daughters, I still don't know how to braid!

Note the two switchable pots, the one on the left is the VRM/Power switch and the one on the right is the Master Volume.

Because my rig is a combo and there wasn't much real estate to mount the pot, coco and I (more him than me) discussed combining the power switch with the potentiometer. That way, I wouldn't have to hack the faceplate, and the relevance of the "Power" label would be preserved. So you pull the knob out to switch on the power, then adjust the pot to adjust the volume via the B+. I measured voltages from a low of 27V, with the pot at the lowest position to 366 with the pot all the way up, which, I believe is nearly what you'd see without this circuit in place. Right on!



As a further testament to coco's documentation, and despite an error wiring the power switch part (I connected the wires which allowed the indicator to switch on and off, but power to remain always on), which I made because, I made an error rotating the pot to solder it up. Otherwise, the modification went smoothly. Once I (with phone support from coco) rewired the power switch, the thing worked as advertised. Awesome!

I noodled around with the guitar a bit, but since the aforementioned girls were asleep, I didn't test the louder side of the volume scale. Initial impressions are this thing is quiet and seems to work well, preserving the crunch even at tiny volumes and becoming transparent as you crank it!

I hope to record some clips when time allows. Some at low volume, then at high volume to see what the ears tell us.

Another winner, coco! Thanks!!

JP

Thanks jrock. We'll see how it sounds at various volumes. Now we've put them an 18 & a 15. Keep us posted on how the field trial goes.

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Sorry, this is so funny. I have 1 daughter (20 now) but your just going to have to learn to braid. That's the problem with a daughter (is that a problem, lol)
Of course I cheated. I grew up with no brothers and 2 sisters.
I know how to braid,
It doesn't matter what your amp looks like as long as it works well.
Some of are perfectionists and we never get anything accomplished.
Keep us informed.
I intend to put the VRM in my sIII, then maybe in the TC-15. It's going to depend on your trials.
Good luck with the braids

Coco, on the TC-15 resource drawing. Are you suggesting using a 1 mg concentric switch and removing the old power switch.
Curious, I have concentric switches around, just have to locate an appropriate one, if that's the case.
Thanks,
Jac

Stephen, no luck on the preform Sil-Pads for the TO-3P/247AD package. I know I also had a 2" roll of the stuff somewhere that would have been ideal for this application. If I come across it I will send it your way. Actually though after thinking about it, if you require electrical isolation between the MOSFET and chassis ground, the more rigid mica isolator may be a better choice anyway. Don't forget that less is more with that thermal grease! You want thermal conduction not insulation!!! Man I hate that stuff...

I'm still not crazy about the cantilevered side of the board, the opposite side from the mounting screw with the eyelets, high voltage, chassis below, etc. Maybe a small piece of sticky-backed foam (just a bit thicker than the MOSFET for slight compression of the foam) under that end, just for a little insurance from the inevitable. (Just one man's opinion, FWIW)

Joe G

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Some assembly required,
Brain sold separately...

I provided a 1M A pot with pull switch for that installation. Not everyone will have that in which case the rear mount like the 18 might be easier.

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

I hear you, but that FET is quite thick in that package so they are reasonably separated. The foam would have to be up to the 40 deg C heat.

I trim the leads off very close to the board as you can imagine.

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Hey guys.

I went liberally with heat conductor material, but a lot got squeezed out when I tightened down the bolt.

When I re-did the wires, I only left enough to get through the eyelet and not touch the chassis; so far, works like a charm.

Got a chance to trial this thing tonight at all volumes - love it! If I didn't like the way the MV alters the sound in the 6-12 o'clock positions, I'd probably yank it in favor of the VROOM.

Tried on boom, sounds as it did before, lower the volume to a whisper, that is, acoustically the guitar is louder, and the same sound! Not terribly useful at that level, but with particularly fussy roomies/neighbors you have the option to be as quiet as you please.

Need a bit more time to play with it, but as I said another winner!

Kewl!

JP

This is good!

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

See, this is very, very interesting! As I understand it, this would be a fairly simple retrofit after I get the amp completed, right? I don't have sound-proofed rooms to crank the amp in, and was consideirng pentode/triode switches, but this might be more useful...

That's what we're tying to accomplish. We wanted to see how it stood up in a TC15 and 18. Other designs have had too much voltage drop or were noisy in certain applications. So far, with this design, it's quiet & minimal voltage drop i.e. less than 3 volts.

For most people, the challenge will be where to put their control pot. In this one, we tried our switched 1M pot to replace the power switch on the front. On an 18 watt Plexi, we put the control in the back.

So far so good.

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

For giggles I may try and build this circuit right on the back of the pot, easy in-easy out, run a ground... done.
Still have those darn heat problems though!

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Some assembly required,
Brain sold separately...

has anyone effectively tried one of these in a v6?

got my amp completed yesterday and my wife says it's dam loud......and the dogs keep singing with it.

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stephen
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If you need to find me, just go to the end of the longest line.

Yes, that's the problem and without the heatsink, it gets hot too.

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Works fine in a reg 18 watt. Cant see an issue with the v6 except where the pot will go!

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

it could go in the 2nd output. i don't really have much need for 2 outputs right now. my cabinet has 2 jacks, so i can daisy chain there if i want to use 2 cabs.

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stephen
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If you need to find me, just go to the end of the longest line.

How about a dual concentric pot in one of the volume control positions? The knob would be different, but no mods to the chassis.

Joe G

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Some assembly required,
Brain sold separately...