Hello MAD COW ... I have a Classic 50 head, never been serviced. Love the amp, been "my sound" for 20+ years... However, it has become really harsh and ice-picky, super midrangey/honky and seems to wave in and out of bad > to worse. It's pretty much unplayable at this point. Wondering if you'd consider servicing and "modding" the amp for me, to bring the amp back to life?? Can I send you a DM to discuss??
Don't ask for exclusive EF86 input mod if you don't want whole video disappear. They say EF86 is too noisy for guitar inputs, despite Vox, smaller companies, diy crowd and others using it with great success in a typical 18W or 30W combos, others too. Shock mount with O rings.
ciao nice tone , congrats !! what kind of diodes your head has for bridge rectifiers in the power supply ? if i remember correct xtc used 1n539 series but i could be wrong Thanks in advance
How exactly are you measuring the current? I saw another video where he calculated the current using ohm's law, measuring the transformer's resistance and voltage difference on red and blue/brown wires, which are connected to your probes... Thanks.
I repair electronic musical instrument gear and as part of this I modify tube amps. This series of videos was posted to highlight the amp after mods for potential customers.
Sounds great!I just purchased this amp in the head version.I am very happy with it except for the very weak reverb.I have to put the reverb on 10 to get the level of reverb i get on my PRRI and DRRI at about 5 or so.I have heard that the reverb circuit is a different circuit being that this is a higher gain amp.Is your reverb weak?
I have the combo version of this amp and the reverb is quite huge sounding. The cable going to the reverb tank is extremely short and can pull off easily which happened to mine during shipping. The pin actually broke so I had to replace it and I used a longer cable as well to prevent further issues. It’s a pretty easy check to do and you won’t need to break into the upper chassis.
I took my logo off this head as well In 91 and I still use it with out that logo on a vintage Marshall 412 cab -- the logo was just to metal pointy vibe for me - looks nicer with out it and grabbed me when I saw this video … just like mine
I am most active on Instagram...which is not very active. Too busy fixin and modding cool music gear. Please Email info@madcowamplification.com with any questions.
The clarity of the drive channel is greatly improved with the mods as well as a more balanced EQ. The gain is much less “fizzy” after the mods as compared to a stock Classic 50. More organic, dynamic and responsive while being less harsh and compressed.
@@Rainman66 yep, these are mods I developed for a customer several years ago and have repeated many times. Please email info@madcowamplification.com and I’ll reply with pricing, details how to ship, etc.
Hey there, I have been having quite the time trying to locate a proper schematic on this head; all the ones posted on the web list having five preamp tubes. Any direction would be greatly appreciated.
www.thetubestore.com/lib/thetubestore/schematics/Peavey/Peavey-Classic50-Schematic.pdf You may be confusing each half of the 12AX7 dual triode as being an individual single triode tube. In which case, you should not be inside the amp in the first place.
@@racmusiccom pfff. Let the guy discharge his caps and figure it out. You techs act like nobody has business learning how to work on their amps. It's not like people can just easily go to tech school or find a mentor.
I bought a brand new pair of gt el84s grade 5 for my blues jr but when I put them on and turned on the amp I noticed quiet hum that wasn't there with the older tubes so I checked the grade o f the old tubes and they were number 1. Is this bad? Did i damage the amp or tubes?
Sorry for the slow reply. I obviously don’t check RU-vid account often. There is a chance you have a damaged resistor in the filament supply that is causing the hum. You should really have a qualified tech check it out. And these amps routinely average 90-110% max plate dissipation at idle. IE wayyyyy to hot. The short of it is that every Blues Jr really needs to have the negative bias voltage increased so the tubes will run cooler and not flame out like they often do.
Hi mate im looking to replace stock ruby el34bht from my 2010 diezel vh4. Diezel now recommend jj kt77 but i want to stick with el34. Am i best trying the tad el34bstr? I heard the bhts are for higher plate voltage so would this cause an issue if i try those TAD?
Just bought one, love it. It is what I've been looking for. This time around Marshalls aren't doing it for me. Had a 27 year break from guitar playing. What I like is it sounds great with various guitars. Like Joe I switch guitars often. I've been doing the impedance mismatch thing for many years with stereo equipment, sometimes it works other times it don't. This Z-master mismatch made in heaven. Everyone is talking about a 1957 Bandmaster, I believe it was a 1959. Anyways an original Bandmaster goes for $6000 and the Zmaster goes for less than half that and it's a new amplifier. This was the first brand new amplifier I have ever bought was a little scared from the new smell of it burning off some paint or chemicals. I had that smell from new ham radio amplifiers too. That's another thing look up to Joe for. Mike
One more reason I am glad that I moved my tweed blues junior down the line. The first reason was pots soldered to a pc board without nuts on the face of the control panel.
Hallo RACMusic Thanks for the the video. Could you give one mor information how you exactly conect the Multimeter for current and the ohter one for voltage.
This may be the best c50 demo i have ever seen to show the dynamic range of the classic series. Hope nobody else sees this video, or used value will skyrocket on these VERY underrated amps!
" The Blues Jr is a fixed, non-adjustable bias amp (like Mesa). This means that the bias supply was set at the factory, and changing it requires removing and replacing a resistor on the PCB to adjust it (or modifying the amp to make it adjustable).'
Phillip Holmes yep, factory circuit in the Blues Jr is fixed negative bias. And my preference is to mod the bias circuit and add a 10k bias pot to the chassis so it is easily adjustable in the future. But adding a resistor parallel to R51 or R52, depending if more or less negative bias voltage is needed, will get it done without having to pull the main pcb.
My roommates Blues Junior is bias very hot stock , it can eat tubes so I put the toughest sovtek tubes that can survive the bias ! I think the different versions vary , there are 3 different ones now !
@@racmusiccom I have a hot rod blues jr iv with a black pc board. It seems to be built much better than the previous versions. I have had it a little over a year now & I play it average 2-3 hours a day, everyday since I ordered it from fender. Never changed anything on it yet & it plays & sounds better each & everyday. When I decide to replace the power tubes, I will order the same tubes from fender & I shouldn't have to adjust the bias. So many people trying to reinvent the wheel.
@@MAP448 spending a few extra dollars on the “correct” tubes will not address the fact that the non-adjustable fixed negative bias design of the Blues Jr sucks. The circuit design is at a fixed point that is too positive and the vast majority of the time biases the output tubes at or beyond 100% idle plate dissipation. Fender didn’t set this voltage as most Boogie amps so they run cold and can safely operate with any grade output tube. It is the exact opposite. Which is why so many Blues Jr amps with the stock bias supply fail catastrophically. btw Groove Tubes are simply rebranded EH and JJ for a 60%+ price increase to have the GT name applied.
@@MAP448 “if the tubes that came with the amp go bad then u can replace those tubes with the proper replacements and not have to bias your amp”. In most circumstances with a tube amp that has a fixed negative bias voltage applied to the output tubes… this statement is FALSE. And in regards to a stock Fender Blues Jr, this statement is always FALSE 100% due to the detailed explanations in my prior comments here. The reason I am not letting this go is because you are spreading false information in my comment thread that was intended to share factual information about the operation of a stock Fender Blues Jr. I listed my credentials to underscore that you are not having a difference of “opinion” with someone like yourself with no technical knowledge, understanding or experience in this field. This is what I do 40+ hours a week 52 weeks a year, in part, as an authorized agent for Fender …the company who manufactures the amp that is the topic of this video. You could have several PhDs in medicine, philosophy, music, etc…you could even have a degree in Electrical Engineering…but only your lack of knowledge in the operation of a fixed negatively biased push/pull output circuit is what is relative to this post. And again, the reason for my unrelenting corrections is because you continue to insist your blatantly false “opinion” is correct. For everyone else reading this thread I’ll leave it like this, all Fender Blues Jr units (with the exception of the most recent revision to a cathode biased output section) should have the fixed negative bias voltage adjusted to ensure safe operation and optimal performance.
Do you like the Sovteck preamp tube. I currently have the Chinese Groove tube. Just ordered off ebay and old Sylvania Baldwin tube to replace V1. Have no idea whats going to happen.
I wish I lived closer to your shop. You did some warranty work on an Egnater for me a while back. It was a couple hour drive to get it to you. Top notch amp tech! I appreciate your skills!
That's not a block logo. Block logo refers to the Eddie Van Halen signature on the front of the chassis. This is still an excellent amp but they do contain different components and so have slightly different sound.
Eric Gutierrez Nope!!! It was that the block letter had Sylvania tubes in them that made a world of difference...all the way to 6505 are the same exact amps!!! Try the Sylvania tubes!!!,,got them in my 5150 ll and let me tell ya.........
