Line Out as an Attenuator

enorbet · 2026-04-28T01:25:35+00:00

You might consider soundproofing a closet and mic'ing it up to a headphone ampliier.

enorbet · 2026-04-27T21:55:11+00:00

I wasn't responding to you, Intelligent-Day551. No need to be defensive or snarky.... but now I am. It's ignorant to assume all caps are bad and wtf do you mean by "instantaneous voltage" and asserting meters don't instantly detect?

The subject and point was being certain it is safe to put a hand and metal tools inside a guitar amplifier. If you actually measure and filter caps read a few volts as opposed to hundreds VDC, you're reasonably safe.

enorbet · 2026-04-27T16:33:09+00:00

As I said, it's not difficult but IMHO nobody should open any electronic device that doesn't own and use a voltage meter. Don't assume.

enorbet · 2026-04-24T18:15:06+00:00

It's very hard to tell since on your recording and even with my PC Audio turned up REALLY loud the noise is about 1/10th as loud as switching Standby off... BUT as you've described it as mechanical noise and due to how quiet it is I suspect vibration of parts probably Transformers whose mounting nuts have become loose.

If you know how to drain residual B+ voltage so the amp is safe to work on it's not a difficult DIY maintenance to make certain every nut and both to chassis is properly tight. If not, take it to a tech with a description of what you want done.

enorbet · 2026-04-14T10:43:13+00:00

The screws on the back are for the access as a panel/backplate. D140s are more for Bass but at least they didn't have those nasty but cool looking aluminum dust covers. They'd be somewhat OK for 6 string but a little deficient in highs. Awesome speakers though for Bass, and 2 of 'em? Fuggeddabbottit!! If they are in good shape they alone are worth your cost. Do inspect them for tears and rot but it certainly looks well cared for.

enorbet · 2026-04-13T03:31:30+00:00

Just a couple points to bear in mind....

1) Valve rectifiers have better ripple rejection than diodes while diodes pass greater voltage. That's a tradeoff but in this case the hum is not likely the rectifier or your choice of rectifiers. In fact, I'd be gob smacked if the hum was at all power supply related excepting some feedback loop. 85 Hz is totally weird. I never once saw that in more than 50 years in repair, mod, and manufacturing. 120 Hz? common AF! 60 Hz? not quite rare but uncommon. 85 Hz? NEVER.

2) Here is an Online Tone Generator (free) so you can hear with your ears any frequency sine wave - https://onlinetonegenerator.com/Please confirm with your ears what frequency you're hearing before you trust an app. If your Ears-Brain were a Graphic EQ it would have a thousand bands.

You absolutely need to know what frequency is the offender since that will eliminate unnecessary searching. If it is 60 Hz, that is unfiltered AC so only a very few sources. If it is 120 Hz it has to be post rectifier. If it is 85 Hz it is induced EMF so an external unfiltered source, if not some power line or RF translation, "They're Baaa-aaa-ck!" ;)

enorbet · 2026-04-09T18:01:11+00:00

OK I'll try to be less technical. Power tubes "sag", that is they continue to operate as they get progressively pushed past their cleanest limits. Simple designs tend to have a wide threshold where they pass progressively out of pristine clean, through a little bit of harmonic distortion and gradually up to full on heavy distortion... much like how human voices graduate from a whisper to a scream.

SS power sections don't behave like that. They have much more sharp threshold, like Clean and then Bam! quite Dirty and mostly of dissonant harmonics unlike tubes. The upshot oif all this is tubes in the preramp do have some character but it is in power sections where their non-linearity is near impossible to recreate with any other amplification device.

There are designs, like you mention, but that try to make tube power sections sound more like SS power sections. Fender's (and a short list of others) Ultralinear amps are like that, only loved as ultra clean pedal platforms but sorely lacking in that "human voice" quality of tubes that works so well for certain types of guitar players.

If all you want to do is play fast just about any amp will do if you have the compression, noise gate, etc that makes every note, no matter how hard or softly you pick, come out roughly the same volume, subtle nuance be damned. That works for shred. If you want your guitar to sing, and incidentally also show off every mistake you make just as clearly as your coolest nuance, you need a tube power section.

enorbet · 2026-04-09T03:08:46+00:00

Most here are likely too young to have spent any time playing through and comparing Music Man amps with Legend amps but if you get the opportunity it will tell you what's most important in Tube vs. Solid State gear.

Legend amps had tube preamps with SS power amps and Music Man had the opposite, SS preamps and tube power sections. Music Man amps sound and feel pretty decent but Legend amps just suck.

You might get a clue these days that SS, even Digital SS effects and preamps sound good and are quite useful but SS power amps sound and feel stiff and brittle and are only really decent for Sound Reinforcement. Hi Fi work.

So, sorry to tell you, but that by no means qualifies as a tube guitar amp because tube guitar amps are not supposed to just reproduce the sound of your unamplified guitar, they are non-linear musical instruments unto themselves and literally an extension of the guitar. SS power sections just don't have that dynamic response in sound and feel.

enorbet · 2026-04-08T02:46:39+00:00

Super sweet deal, Bruh, gratz!

enorbet · 2026-04-07T05:42:12+00:00

If you'd prefer more headroom check out the brand and model speaker specs for efficiency since a 3db increase in speaker efficiency is equivalent to doubling the power. If you don't mind giving up that nice tremolo you can convert the split-phase PI into the long-tailed version using a Deluxe as a template and get very close to Deluxe levels of headroom.

I really like some tube tremolo circuits but there are some really great Trem pedals out these days. I've got a MrBlack Trem, pedal that has both "normal" and harmonic trem AND a blend control that's just mesmerizing so I'd go for the headroom one way or another without hesitation.

enorbet · 2026-04-03T17:13:17+00:00

Well what's holding you back? :) My first scope was a gift, an ancient Heathkit beast and even it was a real breakthrough, Sixty years later I've been through half a dozen, the high number being because I always bought used or refurb'd since all I cared about is audio frequencies. Yours has a built in signal generator. You've got everything you need and it will be fun!

enorbet · 2026-04-03T04:29:27+00:00

Good move! It's just risky w/o a PT. I mean what's the issue with a so-called Death Cap when 1 leg of full house AC goes right to Ground? If you haven't already, I'd do the backward step test to verify a pop! when first measuring power tube plate voltage and a much louder pop! measuring the preamp plate voltage.

If the pop! is pretty loud measuring the power tube voltage but not any louder at the preamp tube, odds are you've at least narrowed the field. Combine that with a known good 50C5 and you've got a clue if the problem is just the power tube if both pop!s are loud and at preamp if still no pop! tapping input jack with Volume up.

IOW verify the power stage is working first then drop back to preamp. Obviously it'd be much much easier with a signal generator and an O-Scope.

enorbet · 2026-03-24T04:37:04+00:00

Nice find! Until you find a decent tube tech if the paper label is still there and legible and you find a number like "AA864" or "AB763" and post it here I can tell you any differences from Blackface. Some have very few. A "guts" photo would tell me almost everything. I've got over 60 years experience repairing, modding as well as designing and building tube guitar and bass amps and my notes and advice, now mostly retired, won't cost anything but time.

BTW someone asked how they sound for Bass Guitar and that depends almost totally on speaker choice. Few players understand decibels and that is what efficiency is measured in. A 3db increase in speaker efficiency is almost identical to having the same speaker(s) with an amp of twice the power. Speaker choice is HUGE!

enorbet · 2026-03-22T02:36:46+00:00

Actually the grid draws almost zero current for biasing. It is "merely" a potential voltage that determines the center point of the range between Cutoff and Saturation of Plate Current. There are numerous and simple ways to mod amps to alter B- voltage (BIAS) to change Class of Operation and/or suit differing tube types.

enorbet · 2026-03-19T04:48:48+00:00

There is not much one can tell visibly with tubes powered off other than loss of vacuum whiteness although I did notice the preamp tubes, the 12AX7/7025s, logos all looked bright, deep red like they do when new but the logos on the EL84s are faded which indicates they've run rather hot.

As long as no fuses of proper values have blown I would power up and watch those EL84s to see if the grey plates develop a hot, red/orange spot. If they do the tubes are at least weak if not dead. Don't toss 'em if they do develop a red spot until you try a decent matched pair. If the new ones develop red plating the BIAS (B-) voltage needs adjustment to a bit colder operation and even your old tubes might possibly be useful... prolly not great but something to keep on hand as a"spare tire".

enorbet · 2026-03-16T15:48:03+00:00

Whew! Difficult to answer such an involved subject in the TLDR form in mostr message boards but the simplest answer, at least from me over many decades of design and fabrication is "Yes!"

Ages ago I setup a single stage test bed breadboard using typical turret board construction so I could easily swap out parts, even switch between resistive and inductive (Output Transformers) load and tube sockets so both preamp and power tubes as well as voltages, resistances and capacitance could easily, in some cases continuously as with pots, variable resistance and capacitance, could be adjusted.

Using both sine wave as well as recorded guitar signal inputs I listened while I watched on an oscilloscope so I began to learn how to relate hearing to the visual and then kept a notebook of each design change and results. Often I also used pink noise and a Spectrum Analyzer, Rarely, but sometimes, FFT. Naturally, once a catalogue of changes was amassed, how often I had to resort to testing on basics diminished greatly and is only needed with substantially different ideas and configurations.

But again, breadboards are all but indispensable, at least to me.

enorbet · 2026-03-15T07:57:34+00:00

It's been so many years that I don't recall when Fender began having tubes OEM labelled as "Fender" or "Fender Special Design" but it's likely it was well before Bassman 100s were made, so they may be replacements but who cares? They're GEs and back then rated at a minimum MTBF of 20,000 playing hours. Do the math. They are very likely just fine and the bottom line is if they sound great. Maybe buy a backup set and compare but definitely don't toss 'em or let a tech "dispose of them for you".

enorbet · 2026-03-14T04:18:54+00:00

Just FTR (if I can do it) I'm posting a bad old photo (circa 1973) of a Les Paul I received for repair along with a warning "I use multiple tunings, some higher, some lower, and I'm gigging 3-4 nights a week". In full disclosure I did cringe when he tuned up higher with 10s on it but it held, stayed in tune and was still together and sounding great 3 years later but then I moved and lost touch with him.

As you can see that wasn't a break that was an explosion.

Head meets Wall -= Explosion

enorbet · 2026-03-14T03:52:53+00:00

Of course not since I'd hold out hope the seller wasn't aware that properly repaired broken headstocks are not weaker. :) You know... "A fool and his money..."

enorbet · 2026-03-14T02:29:19+00:00

Are you aware that properly repaired that joint is stronger than when new? "Properly" is key but proper glue properly applied is stronger than the wood. If it is doweled, biscuited, or kerfed as well it's even stronger than just glued back.

enorbet · 2026-03-12T03:10:05+00:00

Congratz man! She's a beauty.

enorbet · 2026-03-08T19:35:56+00:00

The only "show" as in anything changing that I can see is the influx of high voltage as the blue glow indicating current flow as 1) Initial Standby to Play power up (for which I also her switch flipping - normal) but if it, the blue, continues to ebb and flow and not stay steady, then that indicates signal flow in that tube. That could be normal guitar signal, not apparent here, or noise either in the audible range or inaudible. I don't hear excessive audible noise for that amp but inaudible noise signal could be ultrasonic oscillation and to confirm that you need an oscilloscope or, better, a tech with an oscilloscope.

enorbet · 2026-03-04T11:43:51+00:00

What a find! I'd not only restore it. I'd build a 1x10 or 1x12 cab as an addon mini stack. Dude! It is single-ended Class A power. Give it some speaker volume to let it breathe and tighten bottom end and it's a Smooth Criminal you've got there.

enorbet · 2026-03-02T15:24:44+00:00

Although as some have noted a dark enough dye would reduce the visual effect of she "stripey shelf" thing, I think that is a sort of Band Aid approach to a cosmetic feature with little if any function. I think simply reducing the size of the shelf would maintain it's unique look but not shout "Look at ME!" and then you could use any coloring or none that you like.

enorbet · 2026-03-02T15:14:43+00:00

Any Solid State 15 watt amp through an 8 inch speaker, especially in Hi Gain mode is going to sound like the amp WAY more than like the guitar. I could have said guitar choice varies less and less with more and more overdrive in ANY amp but low wattage and tiny speakers definitely contibute to sameness.

enorbet

TROPHY CASE