trinityamps.com

Would I be losing anything useful if I used a VVR instead of (rather than in addition to) the amp's master volume control?

Hey drew.

I have the VVR (Stephen calls it the VRM), in my TC-15 as well as the switchable MV. I added the VRM after the original build and then the VRooM. I can say you won't lose much if you don't use the MV, in my opinion. I have only used the MV to alter the tone and get a thinner sound, but if I want to stay true to the tone without the wattage, I hit the VRM.

Here's my post: viewtopic.php?t=1204

I like the idea of having the pot where the toggle for the power was, just makes sense

VRM!

JP

I like that idea too, thanks! I'm thinking one of those pots where the switch is off when the pot is on zero, when you turn it - it clicks on. That way you always have a visual of the "power" setting.

At least now I have 3 options - back panel, MV or power switch.


Sorry, I have VVR stuck in my brain. But this does beg the question:

Is there any difference in the cathode biased VVR circuit and VRM?

Thanks

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Deric®

yes! Coco developed his own version

Today's questions....

Can I use 1/4 watt resistors on the contour switch or should they be bigger? I have 1 watters too but figured it would be easier to fit the smaller ones on the switch...

What change does the 5r resistor in the VRM circuit make compared to the 10r in the VVR?

Thanks!

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Deric®

1/4 watt is OK.
The 5 ohm vs the 10 ohm will ensure there is no noise or voltage drop on our mosfet design. It current limits the FET to a higher value than the original VVR, but then I think he's changed his design.

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

Finished and fired it up late last night. Voltages are all a little on the high side using a new JJ GZ34 but they are close. I'm probably going to add a 220k bleeder resistor to the first cap so that might drop a couple of volts.

At first I had a very low output on the EF86 channel. Quickly tracked that down to a 470r resistor on the volume pot instead of 470k. Now all is good.

The tone controls on the other channel seem a little goofy. It was late and didn't have a chance to play much after tracking down the other problems but, as I turn up the Bass control I get more bass untill about 2 o'clock and then a very noticable decrease in treble. The treble control seemed to do something similar.... It was late and my eyes and ears were going buggy so I called it a night.

Edit: Just checked the voltage chart in the Resources section. Looks like I'm right on the money

The good news is everything else worked correctly, no smoke and it's very quiet.

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Deric®

The Tone controls are interactive. Check out the post on that. Sounds like it's working correctly.

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

Coco,

Thanks. I had a feeling that was the case.

Looking forward to playing it tonight.

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Deric®

Had a chance to turn it up tonight . Sounds great!!! The tone controls will take some getting used to but they are VERY cool!

Double checked voltages with the ones posted here and considering my line voltage is about 5vac lower, everything is right on the money. For now, my MV has no switch - need to order the right pot. Will probably do a VVR/VRM soon. Other than that, just to need to decide on colors so I can order a head cab from Trinity.

Big THANKS to Coco/Stephen/Trinity!!!!!!!! and all who answered questions here.

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Deric®

Deric, congratulations! This is clearly one of the neatest wiring jobs I have seen. But the best part is playing it and hearing those rich sounds. Enjoy!
Jim

I second that... Nice wiring job Deric! I'm sure it sounds as sweet as it looks!
Enjoy!

Joe G

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Some assembly required,
Brain sold separately...

I third it. One of the nicest of any I've seen.

Wanna share your secrets!!

Which EF86 did you go with?

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

Thanks guys! No secrets, just patience and a bitchin' layout to follow and a great chassis . The build was spread out over a couple of weeks so that helped. Plus my kids were gone for a few days...

So far the only tubes I've tried are JJ's.

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Deric®

Swapped the Power Switch for a Pot/Switch and VRM/VVR/VVRooM Works great. The pot is a 1MA - should be linear. I will swap it out for a linear taper pot when I get the chance.

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Deric®

Nice job. Where did the board come from? What is your B+ with it in the circuit/ out of circuit

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

I made the board myself. It worked out really well. The board is supported by both the pot and the mosfet which I like. The layout also keeps the leads as short as possible and takes up very little space.

B+ measured at the standby switch (switch ON):
Before: 360vdc After: 359vdc

I expected a bigger (2-3vdc) drop. My mains voltage does vary by about 3vac and I didn't re-check the mains voltage with each measurement.

I can post the board layout if anyone is interested. Even though the VRM circuit is a little different, it should fit just fine.

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Deric®

Yes,

A new posting of the board and circuit perhaps, would be really helpful.

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

Here it is...




I believe Dana currently recommends a NTE2973 fet. I used NTE2377 because I had one... The 1M Linear taper pot with switch is Mouser # 31VM601-F

I have an extra board (made 2 just in case) if you want it.

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Deric®

Really, seriously, very nice job.

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