1958 Sound Projects Lectrolab R500 (REPAIR, DISCUSSION & DEMO)

[@mikemoyercell]

This amp really reminds me a bit of my Harmony H-304a only my Harmony is single-ended.

[@herbalbert]

For $250 I just scored an all original 1959 Lectrolab r200b, tones like a tweed fender champ. The biggest difference is the price--an all original ‘59 fender champ on reverb sold 4 months ago for $4300 🤯

[@zacklineman]

Thanks for the great service Brad! I love having this amp back, it has such an awesome tone!

[@matthewf1979]

Paraphrase inverters have A LOT of gain. The tone control is exactly like the GA-40, just a treble bleed. This amp is the result of a Deluxe and GA-40 having a drunken night at the bar and smelly sex in the back seat of a Chevy 150 coupe.

[@TheGuitologist]

hehe...great comment. Yeah, I know the tone is a treble bleed. It's in a weird spot in the signal chain - after the PI, before the power tubes. Don't see that much, especially from the 1950s. Weird to get this much crunch from a 12ay7 pre.

[@matthewf1979]

The Guitologist I think theres more power tube OD with weaker pre's. If not, I guess I'm hearing things!

[@waynegram8907]

What are the advantages of using a "floating Paraphase Inverter" compared to the "long tail Phase inverter" that fender and marshall used?

[@joemiller9009]

i just had this same model amp come into my shop Tuesday evening. it looks very good and intact much like the one in this video. remarkable that the cardboard cabinets have survived so well. the one in my shop has what looks like a 1950s altec speaker in it. now im eager to see what is going on with it. i wanna get it working today so i can hear it. thanks for the cool video...talk about timely.

[@TheGuitologist]

Everything is timely. We are all connected to the Oversoul, the Interdimensional Mind of God, dude. DIdn't you know? ;)

[@davemassie3726]

Nice amp, great tone. I have the R 200 B, with 8" Jensen. Great sounding Amps. Thanks for Vid. keep em coming Brad.

[@leewarren]

Sounds good, and nice picking too!

[@TheGuitologist]

Thanks, Lee.

[@BenPrevo]

Gridleak bias inputs -- some supros and early fenders too

[@TheGuitologist]

The Harmony H415 is a Lectrolab product too, and it's inputs are gridleak biased too. I think it was a thing with Lectrolab.

[@yrulooknatme]

looked like an easy circuit to replicate. like to have one o those hangin around. nice information sheet in that. you always run up on cool stuff.

[@snakehips81]

At the end of the video, you accidentally call this amp an R600 (when it's an R500). I have an R600. It has also got 12AY7 preamp valves and uses two 6V6's. It's got 2 channels, with 2 inputs per channel, AND a Tremolo, and a 12" alnico speaker. Sounds completely awesome with the Kay pancake/zippo pickupb on my Silvertone 1361 guitar, here : soundcloud.com/richard-odonnell-2/home-schoolin-blueswav

[@1991stratplus]

Looks like it's covered in wallpaper.

[@bigfootingermany]

nice sounding old amp, and looks pretty easy to reproduce a modern version today. But when the hell did Gibson start making can openers? And people were surprised with the Gibson bankruptcy....

[@bucyruserie1211]

Hi Brad, glad to have another listen to this really interesting amp. A few things I am curious about that maybe you can clear up. 1st, do you think the speaker is original? It looks like a mid 60's Jensen to me. 2nd, when looking at the 6V6 output tubes on the schematic, you initially pondered over them being P-P or Single ended (parallel) I assume? Wouldn't the center tapped primary on the output transformer tell you immediately that it was Push-Pull? 3rd, I know the 12AX7 has a high Mu of 100, but isn't the crunchy, creamy distortion sound most of us love, actually produced by the tube NOT being able to reproduce and amplify the original cleaner signal accurately? Thus in some instances a lower "gain" tube, like the AY or AT or AU, being that you need to turn the signal volume to the grids up more, maybe start to inaccurately amplify (or distort) sooner? I am sure you checked the the tubes to confirm they were the 12AY7's, you just didn't video it. I don't remember if you said or not, but some of the brown face Fender's used a 12AY7 for V1. Sorry this is so long, just the things that went through my head while watching it. Great video as always, I'm still very much a newbie with understanding amps, sorry if any of my questions seem dumb.. I'm just trying to learn more. Thanks, Tom

[@TheGuitologist]

1: Yes, I think the speaker is a replacement. Can't remember for sure. I did not look at the code, but I think I remember it being a 60s one. 2: Yes. It's obviously PP. I got myself distracted staring at the PI and trying to figure out what it was.The CT is a quick way of determining that, I was just having a brain fart moment. 3: The hairy, creamy overdrive in amps like this is usually a function of the output tubes being driven to the point of saturation. I would have thought a 12AY7 (which these were confirmed to be) would not slam the 6V6 pair with as much signal. But I am of the mind the overdrive in this one is due to the gridleak bias of the V1 tube and the style PI used.

[@bucyruserie1211]

Wow, I must have caught you at the right time, thanks for responding so quickly.... I was actually watching your other video of the Magnatone 260A... Your making it difficult for me to decide what amp to build next, that 260 sounds amazing. I have never heard of a varistor, so I guess it will just have a tremolo! No matter what schematic I use I think your going to dig it, I picked up a 1966 Lowery organ amplifier cabinet with a 12" Jensen C12N speaker in the normal position and a Jensen10" horn pushing out the side. There was no amplifier in it (it was a solid state unit anyway), but Gibson put out the same unit under there name.. It's mint so should come out nice.. I still have a Hammond AO-43 chassi I could use.. I will send you a link when done. Thanks again, Brad, I will look at the Grid Leak bias and that PI a little closer, Take care, Tom

[@andrewgillis8572]

wow OK now we have enough tube & transformer & ceramic (rather modern) speaker - ready to throw to a room - so what about a dummy box, real wood, floor standing, which this whole amp could sit inside at gig & thus raise position & increase Jensen volume - maybe hang it inside by the handle - just an idea, never seen such a thing

[@chokkan7]

The paraphase driver got a bad rap as 'distorting' too much (can't have that now, can we?) compared to a long-tailed driver, but if you compared the two circuits using the same tube (e.g., 12AX7), the para would have a gain of approx. 100 vs. 25 for the same components in the LTD set-up. Since the para leaks back part of the boosted signal to invert for the pull of the push-pull driver circuit, there is a higher chance that the resulting signal will fall short of the hi-fi standard...sob....leading to its preferred use by perverted degenerate guitar chokers in creating all manner of sick noises...bet Link Wray would have loved this... The chassis construction seems very diligent in most respects, and despite the choice of inferior materials, the cab seems to have been well executed...I can think of worse investments...

[@TheGuitologist]

Great comment and I agree 1000%.

[@Robert-xn3jb]

Love your channel! I am amazed by the simplicity of your workbench. Do you use a scope and signal generator or just the multimeter? If you ever see a Sencore PR570 for a good price it would be a great upgrade over the variac you are using. Thanks for sharing! Robert

[@TheGuitologist]

I have a signal gen and a scope, but they stay on the floor behind the bench and never see use.

[@Robert-xn3jb]

The Guitologist You seem to do just fine with the multimeter. My repair mentor is an engineer at HP and he told me years ago that the best piece of text equipment was your eyes. Keep the great videos coming. Robert

[@davidringo1399]

just bought a 700c Lectrolab......

[@TheGuitologist]

Cool. How you like it?

[@douro20]

Are those light brown resistors precision ones? A bit expensive to be putting into a guitar amp.

[@TheGuitologist]

Not sure about the tolerance on those.

[@jeanettemurphy5748]

I have one of these but a R200. How can I get ahold of you to talk about servicing it?

[@TheGuitologist]

I'm not currently taking in new work. Maybe down the road.

[@SalLopez3Babaganoosh]

Holy crap I just got a 100B and it doesnt work LOL