Various short video clips I have made in my workshop describing my hand-built guitars, amplifiers and guitar effect pedals. Custom electric guitars, guitar repairs and modifications, tube amplifier and speaker construction, are all part of the activities here in my workshop.
Thank you Jason. In my rush to wrap up these vids I didn't drag the EAR copy down to the workshop. It is presently feeding into a source switcher and then the Mcintosh 2105 or Dynaco Mk3s into Pioneer Hpm100s.
I have one of these in my basement that I have been considering refurbishing. I look forward to watching your videos on this. Thank you very much for taking this project on.
I'm glad, you are my target audience. I think your project will go well, as long as all the parts are present. I think the only hassles that would hinder a restoration would be if the platters are damaged. Even the motor can be completely rebuilt easily and all parts are available.
All caps need some burn-in time, and it varies widely. I would have left the amp turned on for 10 to 20 hours before making a judgement and replacing them.
Crosstalk seems to be a common issue with the PASs. I was recently asked to see if I could remedy this on a friend's PAS that I had serviced. I found two things: 1) leads from different inputs are tightly run in parallel together to the selector switch. This looks tidy but causes signal from one input to be induced into the other. Re running these individual wires randomly (it can be done neatly) did help but not completely. 2) The grounds for line level inputs are lifted by a 10 ohm resistor at the inputs. So, although the selector switch shorts the unselected inputs to ground, the 'shorted' inputs are seeing 10 ohms. This will effectivley short high impedance input devices but on something like a cathode follower output with low impedance, it will happily drive signal into a 10 ohm load. Shorting these ground-lift 10 ohm resistors in conjunction with 1) will pretty much take care of the crosstalk. Still, for critcial listening it is best to shut off inputs not being listened to.
I completely understand your hate for complex Marshall designs like the JCM2000 and TSL series and so on. I am on the same page. I am not a guitar amp tech but I do soldering jobs on a daily basis and I am learning guitar amp designs. However I got myself a DSL100H (Vietnamese version) and the design is quite good in comparison to those multiple PCB designs. Definitely not the simpliest design like the JCM800 but nonetheless very workable. Only 1 big PCB that can be flipped to work under it. I am not sure why yours failed (the one you've shown on the video which seems to be the same model) but I would be interested to know what issue it has and why it made you hate it please. Thanks!
This one is a mystery, it came to me with what seems to be two previous episodes of arcing around the power tubes. I.e. previous arc repairs on the board + fresh arcing soot and damage. I did my best to remove arc damage and restore circuit traces, and redo poor work from some mystery previous tech. At the point it was still blowing fuses. I told the owner we need to purchase at least a new set of powertubes and a new main board + labour to have a RELIABLE amp (this came from a rental company and has no value to them if it isnt trustworthy). They then declined any further work and just abandoned it for salvage. In my last looks at it I could not say exactly what caused its problems, it may have been from the known board flaw regarding bias, or it may have been run without a speaker connected numerous times. At this time of writing I do not know for sure that the transformers are undamaged.
You know... I also have a deadish DSL100H here sitting right next to it. Owner has abandoned it at my workshop, who knows it may come to a similar fate.
Hell yea, will watch that one too if you record that project. Took me about 3 months since it was my first build with a lot of help. The transformers were long gone so the power supply had to be redesigned to run what we had. Now it's what the DSL should have been, stock plexi on channel 1, footswitchable extra gain stage in front of the plexi for channel 2. Dual master volume to balance the channels. May try to add a footswitchable solo boost eventually. Might be biased since I built it but holy shit it's the sound I've been chasing for the 15 years I've been playing.
That was very nice of your customer ! This will be a rewarding project I'm sure. I love gutting fender hot rod amps and making 5f6a bassman or plexis or jcm amps. Sure beats buying transformers , speakers , chassis etc etc. One of my upcoming amps will be converting an origin 50 mashall to a 1987 ..
Hello Jules, what do you use them with? In a surprising twist, I recently ran this preamp into a Mcintosh mc2105 and the result was not nice at all. I need to keep my PAS + Mk3s dynacos setup intact.
Dyanco ST-70 series II and an old SCA-35. Obviously it was designed for this use and sounds great. Might not be a good pairing for a McIntosh amp... I will add that in the regular preamp stage (right pcb) I'm running 60's nos Tung Sol 12ax7 's and in the other unit the original dynaco west germany tubes. Might want to experiment with putting in gold lions or something to pair better with the McIntosh@@jothanankrogh
@julesl6910 the mcintosh mc2105 has a stated input impedence of 200k. I am not sure how much of what I hear is an impedance mismatch or sensitivity mismatch or excess gain? But together they do sound nasty.
Yep that's about twice the standard input impedance of most amps, it will require a mcintosh preamp or something like that lol. I envy your "problem" and hope to have something like it some day.@@jothanankrogh
Nice job on the restore, it looks really nice. How does it sound? Did the new three conductor power cord remove the residual voltage on the case? Now you have an amp that will last another 50 years. Enjoy.
Yes it certainly did, with the 3 prong cord I am much safer and there is ZERO hum, and the added 3 prong cord has not created any ground loop issues as some may fear. The sound is great, there is a beautiful dynamic, especially in the bass and mids, I can see why people call these warm sounding amps.
Excellent question, as far as I've seen the Ear834 has no capacitors at its input circuit and relies upon the turntable cables capacitance, mine measured 220-240pf.
I ASSUME you know that a leaky electrolytic does NOT just mean electrolyte physically leaking from its pins or end. You should measure every section for value and ESR, equivalent series resistance. Often is the case, aging electrolytic caps start exhibiting internal resistance and start acting more like a resistor than a cap. I generally toss electrolytics older than 30 years unless it's a Nichicon, Rubicon or other high quality caps. Those I still check and if the value and ESR are good, maybe, allow more like 40 years. Bottom Line, electrolytic caps don't last indefinitely. While on the bench and under the hood is a good time to do this work. AND keep in mind, there are a lot of fake caps with brand names like mentioned. DigiKey and Mouser are a good source for quality parts.
Note: it was some "Audiophiler" 1uf capacitors that seemed to ruin the sound, further use with the stock, orange drops or solen capacitors in that position all sounded good.
Great video thanks for sharing,I've been through much the same experiences,trying to minimise hum and noise,actually found it to sound very nice,have used better low noise valve's but haven't changed any Capacitors yet,I have put power supply board in different enclosure and my next step is to add Chokes and Capacitors on the Heater and B+ supplies to hopefully reduce noise and hum further,one of best things I've found and would advise trying if you can put your hands on one is feed it via an Mains Isolation Transformer.
O dear, now I was starting to entertain the idea of socketed capacitors as well. But unfortunately the sockets probably would mess up the actual capacities seen electrically. This looks like a fun project kit. Hopefully something similar can still be had these days here in Europe, and if it is with pre-drilled stand-off holes (I don’t have a drill press). Cheers
That is a great idea! One problem is that all these capacitors have different thickness lead wires, but a raised turret or pin could work as a much easier solder point for faster swapping
@@jothanankrogh yes, it is a great idea until you realise how much capacitance a socket spring and some unavoidable oxide layers might add (uncleanly) to the system. But then again, maybe it won’t be that bad. Only one way to find out… 😉
Thanks for the video! Ihave one just like that that I bought new in high school. It was my first pedal. I was putting the Stewmac 9v center plug mod in and a wire in the board broke off and I couldn’t see where it went. Found this video and saw where it attached to. The old Small Stone’s like this need the adapter plug wired different than the Stewmac directions show. Got it figured out on my own.
Your through explanation encouraged me to challenge my first diy project of tube amplifier. The first result was very discouraging, but I was lucky to figure out a few mistakes (in a week time) and the sound was fantastic; more than I expected!! I am already dreaming my second project. BTW, do you have measured data (VDC) at each stages of the music line? Although I cannot hear any sound differences between right and left channels, I measured the B+ voltages differ significantly; 244/281VDC. Without the load (disconnect the main board), the B+ voltages for both channels are similar; 294/301 VDC. This difference continues, so the plate voltages at V1, V2, V3 are 73/79, 94/110, 242/279 VDC. I have no idea whether the measured voltages are within expected range or the differences are acceptable or not?? Anyone can share the valuable experience?
Nice work. I have made the same piece but from the competition. I found Mundorf PIO caps after seeing Skunky use them and they are very nice sounding. She also does not trust the supplied resistors on another project and I agree. I purchased some along the lines of mid-range Vishay's None of this is super expensive and you can get a good reward
Hi Jonathan, I have Pas 3 and with a HK Citation I Ithat I have had since the mid 80's. Both was completed rebuilt by a Micheal Fraser in Los Angeles. His design is based off Herbert Keroes from the 50's. In the Pas 3 he has added two 12au7's, not sure why. In the phono section there are two small vertical boards added, maybe for the RIAA. The tone controls are removed. He needed the area for two 450V, 100 MF's each, two zener are added on top of the selenium rectifier. A choke has been added. Numerous capacitors are stacked on the phono and output borads. A couple friends brought their PAS3 over for comparison and the Fraser kill them. The Citation II is completed changed. No more 6 volt TV tubes in it
Hello Tara, sorry for the late reply. I would GUESS that the added 12au7s are for cathode follower stages for the line output, maybe even for the phono too. They probably did something with the power supply to address the extra current needed also. Very interesting to see how complex or how simple mods of this platform emerged.
Does this fix the issue where this pedal kills or deadens the highs when it's bypassed? If this is the fix for that problem I need to get mine done. Mine sounds fine when it's in operation but sucks the tone when not in use, so if I don't need it for the full song it has to come out of my signal chain to keep my tone. Does this fix that
Stephen I hadn't experienced that problem. What you mention could be remedied with a full bypass switch mod, which would require one of those 9 pin stomp switches. I could look into it and maybe do a vid on that.
@@jothanankrogh The original EAR 834P specifies the fuse as 0.1/ 0.2A; assuming 0.1A fuse for 240V and 0.2A for 120V?? I'm using 0.2A/250V fuse (my house gets 230V electricity) without any problem.
Please suggest an alternative! I'm willing to try others, and I was horrified by how much I noticed signal cap differences in hifi compared to their use in guitar amps.
@@jothanankrogh in my experience metal poly caps have flavors and ive never found any that i particularly dislike, except Solen. WIMA, Panasonic, Cornell Dubilier should be a safe bet. Many small (esoteric) brands out there, RelCap has been good.
