About
Well, as you can see, lots of stuff has changed.
I have decided to migrate towards a wordpress-based website for ease of management. You’ll likely see a lot of alterations to the style/theme of the site as I settle on one and customize it to my liking.
There WILL be growing pains, I am sure, but it’s time for a change, damnit!
Though lots of stuff is in flux, there is very much that remains the same… my likes are still guitars and tube guitar amps, tube hi-fi amplifiers, my Subaru WRX, my wife Kristen and my daughter Charlotte. Slowly but surely you’ll see more posts and articles on those things, plus the other varied things that take my time.
Thanks for your patience during the upgrade. Hell I don’t completely know where the site is going, long term–photoblog, or whatever–so check back often and send me a nasty email if you hate it.
-Ken
Ken, I read your review on the Sovtek Mig 100H. Recently my 100H started having a very noisy hum when my guitar is plugged into either the low or high gain input. When there is nothing plugged into the input jacks, the noise does not exist. I’ve tried changing instrument cables, but nothing changed. The power tubes are new. I recently have been running the head with a THD Hotplate. Would this have harmed any internal component of the head? Could something be wrong with the capacitance multiplier transistor circuit that feeds the first tube? Any suggestions would be much appreciated.
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Ken Reply:
February 5th, 2009 at 7:25 am
jason,
the fact that the amp is dead quiet with no input leads me to believe that the problem is external to the amp.
first try plugging in the cord, no guitar. you should hear a minimal increase in hum/buzz/noise due to the fact the cord is an open circuit and is acting like an antenna.
if the hum/buzz/noise is substantially increased then look at the cord itself. swap it with another. if the noise persists then look at the grounding of the input jack inside the amp. if the noise decreases with the new cord, you had a bad cord.
next, plugging in the guitar with the volume rolled all the way down should actually DECREASE the noise level compared to the open circuit, since the volume control would be shunting the + conductor to ground, shorting out the “antenna.”
IF your noise levels get even higher at this point, look carefully at the internal ground path in the guitar itself. check the jack, check the volume control, check the ground to the bridge/strings, etc.
basically take it step by step “upstream” from the amp’s input jack.
hth
ken
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Dude, Call me. (774) 451 6799
bacchus@megabroadband.net
bacchus.brule@yahoo
Lost of stuff has happened in the long period of time we spent apart. I miss you…
LOL
No but really…. contact me
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dave hafner Reply:
February 10th, 2010 at 7:28 am
Ken
You say 300b will put out as much as 40 watts, can you steer me toward a schematic with a circuit that will do this.
Dave
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Hi Ken, this is a great site (USEFUL).
I’m in need of the Service Manual for 2002 WRX. The service manual part 5 (5-chassis) file seem that is not complete. I’m unable to open the file. Can you please check and replace the file (if corrupted). Thanks !!
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alberto–give it another shot. i reuploaded the source file.
you might try it from another computer too.. sometimes the browser tends to cache downloaded files and instead of re-downloading it just pulls from the cache instead.
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please send the 300b pp schematic.
thanks!!!
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he i see you have manuals of impreza
is it of a jdm i need one of a jdm sti v7 is it the same
can send me a mail
greetings johan
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Hey dude nice website and thanks for the tutorial on slew rate.
btw you used photoshop right for the design? I like the effect of the photo being stuck on via the sticky tape looks neat.
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oh btw is the theme available to use on wordpress? The re-hacked theme i just noticed.
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Hi Ken - great stuff, esp on how to build a tube amp from scratch. I’m just learning about electronics, and can you provide some tips on how to pick up enough skills to repair and build tube amps? Thanks!
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Hi Ken good information for me. Please sent schematic diagram all tube guitar preamp
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Hi there! Awesome site!
Do you have any manuals for an EZ30D or R engine?
Thanks,
James
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Hey Ken, I was just browsing your site, and I noticed that you listed a DIY remote map selector for the UTEC. I was considering making one while I have some time off for the holidays…would you be able to help me? Maybe provide some pointers and some info on how YOU did it? Any help would be greatly appreciated!
Thanks!
Josh
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Glad to find your site. Wondering if you could help. I just built a Vibroverb (brown 6G16) and at HIGH input peaks (striking a note hard on D through Low E strings) I get a fizzy unpleasant type of distortion (aside from the normal clipping). Could you suggest a troubleshooting approach? Any info much appreciated.
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Ken Reply:
December 28th, 2009 at 9:43 am
dave. look into the output stage. i suspect you have blocking distortion occurring. you can try reducing the final coupling cap(s) to the output tube grids, or reducing the value of the grid leak resistors, or both.
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You asked a question on my flickr site. Perhaps you were kidding. If not, and you have a serious need for the answer, write me at the email address I filled in here.
I don’t personally have what you asked about. I’m a photographer DJ and I couldn’t invent anything. But the short answer is yes.
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what equiptment do you use?
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nat..
the bread and butter items are:
canon 20d
canon 430ex2
tokina 11-16mm f/2.8
tamron 17-50mm f/2.8
some less-frequently used stuff is:
nikkor 50mm f/1.4
kenko extension tubes
canon oc-3 off camera cord
b+h 10 stop nd filter
tripod, remote shutter relase, etc.
all post processing is done in adobe lightroom and adobe photoshop.
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hi,
cool site!
i am working on a multimedia art project that includes old vacuum tubes. i love the way they glow!
i have been using old radios as a source of ‘ready to run’ tube systems, but i am wondering if it’s possible to buy the transformer, sockets, tubes and any caps/resistors etc so that i could have some more flexibility in terms of how i use these things by wiring up my own little circuit of tubes.
in essence, i’d like to be able to work with glowing tubes, as many as i want, configured how i want. and here’s the key thing: the tubes don’t have to actually do anything but glow and look cool! this is all about looks. it’s as if i wanted to build a car that had no engine, just headlights, and it sat in my garage looking spiffy. or another metaphor: houses glow at night thanks to electric lighting. but you don’t have to buy a house to get lighting. you can go to the hardware store and buy a bulb, a socket, and a plug!
same thing here: i don’t want to have to buy an old radio etc, i just want the minimum pieces required to power tubes so they glow.
does that make sense? does this seem doable? could i trouble you to send me some sort of diagram showing what parts i need and how to connect them up?
thanks for whatever you can do!
chris
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Ken Reply:
February 22nd, 2010 at 5:47 pm
chris: basically what you want to do is run the tube heaters. all the tube datasheets will show you which pins need to be connected to energize the heater. since you are not interested in fidelity you could run the heater circuits on high voltage AC and eliminate the need for a transformer, a heavy and expensive part. make sure that any heaters you connect in parallel require the same voltage, and any heaters you connect in series require the same current. mix and match until you net 120vac.
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Chris Mills Reply:
February 23rd, 2010 at 2:19 pm
thanks, ken. sounds like you’re saying that this is doable! unfortunately i have no idea how to operationalize your prescription..heh heh…though it seems sorta like connecting Christmas lights — this pin on this socket gets wired to that pin on that socket. is that right?
if i can impose upon you for more detail…where do i find the ‘tube datasheets’ and can you give me an example involving actual, rated tubes (that i can easily acquire) that illustrates either a serial or parallel connected circuit (does it matter which?) of, say, 3 tubes in sequence? i could then extrapolate from there, right?
criminy, can this be so easy as to get tubes, sockets, lamp wire and a plug? it can’t be…can it? maybe it can. i just need to know how to physically connect the right pins to suitable tubes, right?
there will be a special reward in heaven for your assistance!
chris
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Chris Mills Reply:
February 23rd, 2010 at 2:20 pm
p.s. can i pay you to make a single such circuit with, say, six sexy tubes, all ready to go, that i can use as a prototype from which to build actual pieces?
ken I wicked favor to ask of you… if at all possible to help me out please send me an E-mail thanks. (its regarding my subaru)
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Hey Ken!
Saw your comments on my blog a while back. Good to see you’re still keeping the geekfires burning.
steve
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Hi Ken, I’m looking into the world of building an amp - and I’m a little scared.
Could you send me the schematic that you first built (By Gary Dahl)? Mentioned your ‘Building Your Own Tube Amp’ article.
Thank you.
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Hi Ken !
For the past 10 months, I’ve been working to build a tube amp…After a lot of reading, I’ve decided to go with a separated preamp and two KT88 monoblocks. I’m almost done with the soldering now but I’m not really sure about how I should connect the female RCA connectors…
The central pin is the signal pin, which is positive. How about the negative pin of the connector ? Maybe you can help me to understand more about this :
1- Should I connect the negative pin of the RCA connectors to the negative bus of the preamp / amp ? At first though, I would connect it to the grounding pin (third pin) of the AC socket since the negative lead of an RCA cable is like a shield…There should be not current or signal through it, right ?
However, on many schematics, the negative pin of the AC input connector seems to be connected to the negative bus (the same bus to which we connect the negative pins of the power supply filter capacitors and the center tap wire of the power transformer). What would happen if we only connect the positive pin of the AC connector ? Would it still work ?
And what if we connect the negative pin of the RCA connector to the negative bus, for both the amp and the preamp, and that, for some reason, the negative buses in the preamp is not at the exact same voltage level of the negative buses of the amps, would there be a current flow in the through the negative wire of the RCA cable ?
As you can see, I’m not quite sure to understand this, even if at first look, it might seems quite simple
Finally, should I connect the metal frame of the preamp and amps to the grounding pin of the AC socket ? I’ve been told to not do this because there could be ground loops resulting from this. Since tube deals with pretty high voltage, I think that it’s still the best decision to ground the metallic parts of the chassis.
Thanks !
By the way, the first site I’ve look to 10 months ago for tube amps is yours…I found it really interesting and this is why I’ve decided to build my own amp…
So, keep up the good work !
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Ken Reply:
July 15th, 2010 at 4:28 pm
matt,
sorry it’s taken so long to get back to you.
one trick that i have done in the past is to connect two high current solid state diodes in parallel, with anode to cathode. a “loop” if you will. then use the common leads to connect amplifier signal ground to chassis ground.
chassis ground must ALWAYS be connected via the ground conductor to mains power.
the diodes have a small voltage differential that must be overcome in order to conduct. this forward voltage is ~0.5-0.7vdc. so by using them to connect chassis and signal grounds together you accomplish two goals: 1) provide a safe path to chassis/mains ground in the case of a circuit fault, and 2) allow for some low level of isolation between the two so that MOST ground loop issues can be avoided.
you can extend the idea with additional diodes. each SERIES diode will add another half volt or so of isolation.
MAKE SURE the diodes are rated for the full fuse rating of your device! if you’ve got a 10a mains fuse, make sure those diodes will hold 10a. grounding stuff is nothing to take lightly. pretend that your life depends on your work, because it just might. a cold solder joint here could be deadly!
also make sure that you practice good soldering technique–namely that a SOLID mechanical connection is in place (ie, by twisting the leads together tightly and to their respective nodes) BEFORE the solder is applied. the primary reason for that in this case is because circuit faults can VERY quickly cause 10s of amps to flow, and this will make connections hot in a hurry… hot enough to melt solder! obviously not the way you want it to play out.
using these techniques i have seen ac voltage differentials exist between the chassis ground and the circuit ground–WITHOUT causing noise in the output. effectively your circuit becomes semi-”floating,” with many of the benefits of lifting a ground and none of the fairly drastic safety compromises.
finally you might want to parallel your diode string with a high value cap, say 1uf or so, to ensure that high frequency crap is drained to chassis ground.. your real enemy with ground loops is 60/120hz (or whatever your mains cycle is).
hth! let me know how it turns out!
ken
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Ken,
Can you please send me the schematic for the most powerful stereo and mono black amps. Also schematic for the best preamp.
Thanks
Greg
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