Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: dbishopbliss on November 05, 2024, 08:43:05 am
-
I have a vintage Silvertone 1482 that I modded a while ago (https://el34world.com/Forum/index.php?topic=25020.0). I had to add an extra filament transformer because there wasn't enough voltage. I also made a large number of changes similar to the ones that jjasilli detailed. Long story short, it was one of my favorite amps until is stopped making sound. The issue is the power transformer died. The extra transformer has been removed and bad one replaced with a Hammond. Also, the leaky caps on the tremolo have been replaced. It sounds glorious!!! Maybe even better than before.
However, it doesn't have quite enough oomph to hang with the loud drummer in my band. Yeah, I could mic it, but that's not happening during rehearsal. So that got me thinking... I built a Supro 1690T (https://el34world.com/Forum/index.php?topic=27432.100) amp a few years ago that I have never really been happy with. I could never get the tremolo to work and aside from that I wasn't able to achieve the tone I was looking for. I was hoping for early Jimmy Page and it just doesn't do that.
So I'm thinking I can reuse the power transformer and output transformer from the Supro to make a 6L6 1482. One difference is the rectifier; 6X4 vs 5AR4. I'm not sure how much that contributes to the sound. And then the 1482 uses two 12AX7 and a 6AU6 versus the Supro's three 12AX7s but that should be no problem for the power transformer. The output transformer is actually for a Tweed Super since nobody make Supro replacements (at least when I built it) so that can handle the 6L6s.
Assuming I start with the Silvertone 1482 layout from Sluckey (https://sluckeyamps.com/misc/Silvertone_1482.pdf) and then modify it with the circuit changes I made to my amp, are there any other circuit changes I will need to make? I realize I will have to adjust the resistors in the power supply and the cathode resistor on the power tubes, but other than that?
-
Takes more to shake a 6L6 than a 6V6.
You may need to use an red LED with the oscillator for more strength. You replace the oscillator's K R with the red LED. Red LED gives the most boost. Other colors won't be as strong.
-
Takes more to shake a 6L6 than a 6V6.
You may need to use an red LED with the oscillator for more strength. You replace the oscillator's K R with the red LED. Red LED gives the most boost. Other colors won't be as strong.
I don't see an LED at all in the circuit. It uses the 6AU6 for the Tremolo. Here's the schematic (https://www.silvertoneworld.net/schematics/silvertone_1482.pdf) I'm looking at.
-
Ah Ha 1482! Got my attention :huh: . Off hand I think installing a pre-amp out and running that to a PP 6L6power amp might be worth a try but that would require toting more stuff but that would keep yoursweet sounding 1482 intact
-
Ah Ha 1482! Got my attention :huh: . Off hand I think installing a pre-amp out and running that to a PP 6L6power amp might be worth a try but that would require toting more stuff but that would keep yoursweet sounding 1482 intact
Given that I have the iron, chassis, head cab and speaker cabs already, I think it makes more sense to try to build something that is more portable and I will use.
I was pricing out iron and chassis and that was putting me over $300 plus another $100 in parts (probably less). Whereas, if I use what I have I only have to pay for the board, caps and resistors (pots, sockets, switches, etc I can also reuse).
-
Takes more to shake a 6L6 than a 6V6.
You may need to use an red LED with the oscillator for more strength. You replace the oscillator's K R with the red LED. Red LED gives the most boost. Other colors won't be as strong.
I don't see an LED at all in the circuit. It uses the 6AU6 for the Tremolo. Here's the schematic (https://www.silvertoneworld.net/schematics/silvertone_1482.pdf) I'm looking at.
Re read what I wrote. I didn't say there was an LED in the Silvertone trem oscillator circuit.
But, that trem's oscillator doesn't have a K R. So, hopefully it's strong enough to shake the 6L6's.
-
But, that trem's oscillator doesn't have a K R. So, hopefully it's strong enough to shake the 6L6's.
What is a K R? Cathode Resistor?
-
But, that trem's oscillator doesn't have a K R. So, hopefully it's strong enough to shake the 6L6's.
What is a K R? Cathode Resistor?
Yes.
How long you been hangin' around here. :laugh:
-
Pentode oscillator has a higher Z out than hi-mu triode oscillator - Use a SS buffer IF you must bias vary modulate 6L6 power tubes - Use with forewarning of potential output stage tube meltdown. Personally, I'd push that to somewhere in the preamp path, maybe cathode couple trem osc to a preamp tube or phase inverter if its a long-tail or paraphase. Modulating the grid of a preamp tube is MUCH safer and IMO if done right sounds just as good as any other scheme devised.
Respectfully,
--Pete
-
How long you been hangin' around here. :laugh:
You are assuming I have short term memory. Seriously, I had viral meningitis that ruined it. That combined with aging, I'm lucky I know my phone number. :-)
-
Pentode oscillator has a higher Z out than hi-mu triode oscillator - Use a SS buffer IF you must bias vary modulate 6L6 power tubes - Use with forewarning of potential output stage tube meltdown. Personally, I'd push that to somewhere in the preamp path, maybe cathode couple trem osc to a preamp tube or phase inverter if its a long-tail or paraphase. Modulating the grid of a preamp tube is MUCH safer and IMO if done right sounds just as good as any other scheme devised.
Honestly, I don't ever use the Tremolo. Does the pentode, even when off, contribute to the tone? Could I just remove that part of the circuit? I know I could, rather if it contributes to the character of the sound could I replace the pots with fixed values and ground it so it never modulates? Would that have any negative impact (e.g. output stage tube meltdown)?
-
How long you been hangin' around here. :laugh:
You are assuming I have short term memory. Seriously, I had viral meningitis that ruined it. That combined with aging, I'm lucky I know my phone number. :-)
I'm sorry to hear that.
As I get older, 65 now, my memory's not what it was either. And I didn't have an illness that effected it.
-
Honestly, I don't ever use the Tremolo. Does the pentode, even when off, contribute to the tone? Could I just remove that part of the circuit? I know I could, rather if it contributes to the character of the sound could I replace the pots with fixed values and ground it so it never modulates? Would that have any negative impact (e.g. output stage tube meltdown)?
No, that pentode is just the oscillator.
You can leave the whole trem. circuit out, it won't change the sound of that amp at all.
Just have to ground the 2 @ 330K power tube grid return R's where the trem. was injected.
-
You can leave the whole trem. circuit out, it won't change the sound of that amp at all.
That's what I figured looking at the schematic.
Maybe I could add in an effects loop. I do use Reverb and Delay. Of course, that would probably alter the sound I like.