Deluxe Reverb Build Problem!

[pdf64]

Well spotted, expect maybe x10 that value!

[Penguin]

Hoping isn't the same as checking. Did you check that there isn't a connection to ground at the back of the bulb assembly that would short out one of your hum balance resistors?

BINGO! There was a tiny amount of solder that was connecting one of the bulb wings to ground! Excluding the hiss from the carbon composition resistors, she’s quieter than I am when trying to sneak a piece of cheesecake at 3AM!

I’d like to SINCERELY thank everyone who contributed their time and knowledge. It means a lot, friends.

[SoulFetish]

Nice work Mick

[1ampman]

Cheesecake? I'll be right over.....

[Jazz P Bass]

Cheesecake? I'll be right over.....

I'll bring the strawberries!!

[Penguin]

Cheesecake? I'll be right over.....

You’ll have to make it by Moose first...


Now that I’ve had a chance to really play it, I’ve noticed a few things. First, the amp doesn’t make a sound until “3” on the volume knobs! It’s literally silent up until that point. Second, it doesn’t overdrive. It basically sounds like a Twin, haha. Someone mentioned that my bias appears to be too hot but it seems too cold to my ears. Thoughts?

[pdf64]

The volume control thing seems fairly normal, bear in mind that it starts at 1.
The correct BF Fender taper for volume controls is ~35% audio; regular 10 or 15% audio taper pots may seem to come up too slowly.

Your plate current measurement of 42.8mA seemed wonky; 1 ohm resistors in the power tube cathode returns may be beneficial to making a good reading.

[Mick Bailey]

I noticed a few years back that some pots - CTS especially - have a dead zone up to around 2 1/2. This appears to coincide with the beginning of rotation if a switch is fitted. So if you have a combined 'on' switch and volume the amp (or whatever) is just about at zero volume at the point where the switch operates. It's nothing more than a personal theory, but I think there's a production rationalization going on to make the same track fit switched or unswitched pots. For this reason I moved to the large Alpha pots and get a more even volume increase.

Your original bias method is correct, but your readings are wrong - take another look at your OT primary resistance, the voltage drop, and recalculate. Rebiasing is perhaps unlikely to give you much drive improvement, especially if it is already optimally set. There are subtle gains to be had at high volume levels if you play around, but often at the expense of shortened tube life. You may need to tweak the preamp side to get earlier breakup.

[Penguin]

Thank you for clarifying the pot issue. I just found it strange how the DRRI’s volume started at “1” and started to distort around “6” or so. The rebuild is nothing like that.

I imagine I should take all the readings again now that one of the heaters isn’t grounded, haha.

[pdf64]

I thought ‘1’ was and is fullcounter clockwise, so the sound should be muted at that setting?
ie have to turn it to about ‘2’ before any sound gets through.

[Penguin]

Rather than start a new thread, I'll ask this question here since it's related to the same amp.

I'm currently in the process of modifying my Vibrato. I'm going to replace the 1M resistor under the optoisolator with a 220K resistor in order to deepen the Vibrato. Is this the correct mod?

I plan on replacing both 0.01uF disc capacitors with 0.02uF capacitors in order to slow down the Vibrato. However, the Orange Drop capacitors I found are only rated for 200V. The stock ones are rated at 400V. The pin that connects to these capacitors only carries 177V. Can I get away with these?

[Enzo]

Hi Penguin, welcome to the forum.

really, it is best to start a new thread for your amp. it may be the same model, but is not the same amp. New threads don't cost anything. We prefer not to work on two identical amps in the same thread. gets confusing, especially for old people like me.

I usually slow down my Fender trems as well, and doubling those caps is the way I go about it. But why cram huge orange drops in there? That oscillator circuit is not in the signal path, so plain old disc ceramics work just fine. They fit well, and easily found in high voltages.

When the trem is off, do your voltages rise?

[Penguin]

Hi Penguin, welcome to the forum.

really, it is best to start a new thread for your amp. it may be the same model, but is not the same amp. New threads don't cost anything. We prefer not to work on two identical amps in the same thread. gets confusing, especially for old people like me.

I usually slow down my Fender trems as well, and doubling those caps is the way I go about it. But why cram huge orange drops in there? That oscillator circuit is not in the signal path, so plain old disc ceramics work just fine. They fit well, and easily found in high voltages.

When the trem is off, do your voltages rise?

Hey, Enzo. Thanks for the reply. I apologize for the confusion but this is related to the same exact amp that I started the thread about, haha.

I haven't seen the voltages rise when the vibrato is off. However, I'll double check before I install them. I picked these capacitors up because the store I was at didn't have the discs. I may go for a drive and see if I can find some.

[g1]

I'm going to replace the 1M resistor under the optoisolator with a 220K resistor in order to deepen the Vibrato. Is this the correct mod?

What 1M ? I don't think a schematic has been posted yet, so can you post the correct one?
Any references for this 'deepen' mod?

[Penguin]

What 1M ? I don't think a schematic has been posted yet, so can you post the correct one?
Any references for this 'deepen' mod?

I apologize for the lack of information on my end, haha.

The 1M resistor connects to one leg of the optoisolator.

Schematic:
http://www.mojotone.com/BF-Deluxe-Reverb-WD.gif

I found that "deepen" mod on a thread about Princetons. I know they use a bias vibrato but apparently, it works with the Deluxe Reverb style vibrato as well. Unfortunately, I can't find the thread!