Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Diverted on February 24, 2020, 03:49:03 pm
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Hi all,
Months ago I built a Hoffman Revibe for a friend of mine. When I built it I had some issues with the reverb not reverbing but was able to get it to start working by adjusting the lead dress around a few of the tube sockets. I remember thinking at the time, 'Wow this unit is really, really dark."
Turns out he thinks so too. The reverb response is not great, and it really is quite dark. Any suggestions on brightening it up?
I know the photos probably aren't much help but I thought I would put a few in anyway.
At a glance the only thing not stock is the 200pf cap from the wiper of the tone pot to the top of the mix pot. I seem to remember not having any 250s so I subbed that in.
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OK, no responses so I'll ask a different question.
This is the only Revibe I've seen. For those who have played them, do they generally add some darkness? Or are they usually/supposed to be more transparent. That might help me hone in on whether the unit's got any specific issues or whether it's right as is. Thanks.
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I don't recall mine sounding dark but I have pretty bad ears. It's also been 6 years since I plugged into it so memory may be a bit fuzzy too. The reverb is very lush though. I doubt 200pF v. 250pF is a factor. Not much help. Sorry.
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A Re-Vibe is not dark
If anything, Reverb units and Revibes are a bit bright sometimes because of the highs in the reverb
I would say there is something wrong with the build
Here's a few tunes I did with a Re-Vibe
https://el34world.com/Misc/Music/files/LoveHurts.mp3 (https://el34world.com/Misc/Music/files/LoveHurts.mp3)
https://el34world.com/Misc/Music/files/Embrujada2.mp3 (https://el34world.com/Misc/Music/files/Embrujada2.mp3)
https://el34world.com/Misc/Music/files/ReVibeDream2.mp3 (https://el34world.com/Misc/Music/files/ReVibeDream2.mp3)
Go here and use this method to double check the build
https://el34world.com/Forum/index.php?topic=17701.0 (https://el34world.com/Forum/index.php?topic=17701.0)
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Thanks. I've pored over it a ton and cannot find any wiring issues etc. Everything works, though as I said reverb response is not super strong, and the darkness. I'll keep looking.
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Back in November I told you V2A and V2B voltages are wrong. You never responded.
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Back in November I told you V2A and V2B voltages are wrong. You never responded.
Hm, I apologize on that, it must have slipped through. I'll be checking those out this afternoon, thank you.
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Mine is a Weber, not Hoffman ReVibe - pretty similar though.
It's bright enough to be really grateful for the tone knob so you can dial back that brightness a bit.
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OK, back at it. The circuit's definitely amiss:
1. Very dark, quite boomy.
2. Reverb response is there, not great. I need to crank dwell and mix pretty much all the way up to get the same reverb response I'd get on say, a Deluxe Reverb at 1 or 2.
3. It's also very gainy. The Princeton Reverb I'm playing through at the moment is much louder and broken up, at same volume setting, with Revibe in vs. Revibe out.
Here are some voltages:
V1A
P: 206
K: 1.5
V1B
P: 207
K: 1.5
V2A
P: 160
K: 2.1
V2B
P: 160
K: 2.2
V3
P: 354
K: 28
K resistor: 1000 ohms
V4A
P: 313
K: 3.2
V4B
P: 332
K: 3.2
V5A
P: 125
K: 1.1
V5B
P: 260
K: .7