tube fanatic

Nice looking amp which, on a quick glance, looks to be stock. The red plate does suggest the possibility of improper bias. No reason not to buy it because of that. How much is the asking price for this unit, and where are you located?

Hi Marty- Email sent. Will chat with you later on. Maynard

Hi Marty- I'll have the schematic some time this afternoon. Will be in touch after I take a look at it. It's a bit too "new" for my database, but one of my radio buddies has it!!!

Marty, if that's an AC/DC radio there are some very definite electrical safety concerns which you should be aware of (especially if you're going to do an kind of testing or measuring while it's powered up.) Feel free to email if you want me to explain the concerns and how to address them.

Marty, do you have the model number? If not, tell me what the audio output tube(s) are and I can help you out-- Maynard

Well, she already has her other half and they both have tattoos and are planning on having some more done. He also thinks they're cool, and he's almost 38!!! I jokingly told my wife that I should have a tube imprinted on my butt and she told me to go ahead if that's what I want. Guess I'm just not "with it!!!!!"

Somehow, at my age, I don't think it would be appropriate!!! http://www.flickr.com/photos/tattooculture/4037519369/in/set-72157622647926510

Hey Sterling! You will be amazed at how loudly the LSs can play with such little power. For a first project, this looks like a good bet imo. Best regards-- Maynard

Craters & Freighters is wonderful. I've shipped large, heavy speakers across the country with them and they do an amazing job. Their packing would survive an airplane drop! All it takes is a phone call and they do the rest. Worth whatever they charge!

It's amazing just how nice a single tube "spud" amp can sound. I have a friend who built one a long time ago when he got bored one weekend (his usual designs are complex variants on the single ended theme.) Tubes like the 50EH5 or 60FX5 are great choices in that the voltage output of the typical CD player is sufficient to drive them to near full output. And with some negative feedback applied between the plate and grid, the frequency response can be tailored to suit one's listening taste.

Erik, I sent you an email regarding an AK10A breadboard with a Model L speaker, etc. Please post if for some reason it didn't reach you. Maynard

Thankfully, I haven't gotten into clocks!!! Given how much I spend on the amplifier and radio stuff I'd get brained with the frying pan if I even brought it up. Vintage communications receivers are amazing and I've restored dozens over the years, mostly for ham operator collectors, many of whom keep at least one vintage station set up. The modern digital ham equipment can of course do many things that the old "boatanchors" can't, but their performance is still breathtaking especially when considering their age (The Hammarlund HQ-180 is still one of the best receivers ever made imo.) I have a friend who has a huge collection of radios from the 20s, including many breadboards, which he's slowly liquidating. If he has an AK breadboard with the 01As for sale, I'll email you with the particulars. And to me nothing compares with the smell of an old wood cabinet radio on a cold winter night when the tubes are nice and warm (my wife has caught me many times with my nose near the back of the radios inhaling the fragrance!!!) Guess I really am nuts.................

Tell your wife that she isn't the only one who has had to live with the insanity that you outlined above! My wife won't even go near the equipment that I use as she doesn't want to be responsible if something blows up (we have a small system in the living room which she uses- tube amp with 1 switch, a tuner, and a pair of KLH 20s.) And I won't even get into the antique radio insanity which is almost as bad. At least she's not afraid to use those. Perhaps a new forum can be started for spouses of insane audiophiles.................... Regards-- Maynard

I think on the brand names its a smart thing to do. Reason is that I find different brands of tubes have different internal resistance and as a result, behave differently..and sometimes are even difficult to bias correctly. For example I have an amp that was designed around the Sovtek 6550, american 6550's are to hot for it, asian 6550's are too hot for it. It will run any EL-34 and only EI KT-90's, EH KT-90's are too hot for it. Interesting point. I haven't run into all that much variance among the US made NOS tubes. I've never used modern replacements (too stubborn not to stay with what I have always used!), but have read that they can perform quite differently. Guess from a marketing standpoint it's a plus in case someone happens to have any of the tubes Deckert mentioned.

Not sure I understand why Deckert is mentioning brand and year of manufacture?????

Hi Erik- Just wondering if you have poked around under the chassis to see if Deckert is using variable degeneration for the treble roll-off feature that he discusses in the promotion: "Finally there is a treble control that has been carefully crafted to take edge off the top end, from barely detectible to substantial so that you can enjoy listening to sub-par recordings or internet streams without going nuts as well as trim the shout right out of your single driver crossoverless speakers in bright rooms." Also, have you by chance measured the filament, bias, plate, and screen voltages if tubes like the 6Y6 are swapped in as he says is reasonable to do? As you know, the filament draw of those is far greater than that of the 6V6, so I'd imagine that the voltage to the filament string sags a bit if they are used. I'm also scratching my head about the different impedance requirement of the 6Y6 vs. the 6V6 as well as the fact that the tube can't be run at the same voltages as the 6V6. Anyway, enjoy the amp! It sure is gorgeous. Hope you can indulge my curiousity. Regards--- Maynard

The typical "receiving" tubes used in amps like this are not prone to cathode stripping from having plate (and screen with pentodes) voltage applied before the cathode is up to temperature. Even tubes like the 6V6, 6L6, and so on are not prone to this effect either. Amps which use rectifiers such as a 5U4, 5Y3, etc. (which ramp up the B+ well before the other tubes are at opeating temperature) do not demonstrate a higher rate of tube failure than amps which use a cathode type rectifier which heats at a rate similar to the other tubes in use.

I don't know where they are located, but even if it's China, delivery can be fairly rapid. For the price though, even a 2 month wait would be worth it. A Hammond aluminum chassis for an amp like that runs around $25, and the transformers alone would push the cost well above what's being offered. Also, even if someone messes things up while building it, the financial loss isn't huge.

A friend sent me this link. Even if it doesn't sound that terrific, for the price it's an unbeatable way to gain some experience with building your own tube amp: http://www.siliconray.com/6n2-6p1-hifi-tube-amplifier.html

Totally agree about the varying speaker impedance issues (wish I had access to some Audio Precision equipment)! However, with speakers that dip to say 3.2+ ohms, the amp can be kept very "happy" by using its 4 ohm tap. The dip of a few tenths of an ohm isn't going to cause anything objectionable at the frequencies at which it occurs, assuming that its output impedance isn't nuts (again, I've never encountered output impedances of 15-30 ohms as you indicated in a previous post.) The higher speaker impedances at other frequencies will then, to a certain point, actually lower the amp's distortion somewhat. Granted, this must be considered in view of the somewhat reduced output power which goes along with it. Anyway, this discussion is fun. Hopefully, those following along will come away with some sense of what this insanity (and being an audiophile tweaker definitely fits the profile imho- this statement is not directed at you Chris; I'm as guilty of the syndrome in my own way!) is about and be able to draw their conclusions from more of a scientific viewpoint. Be glad to continue babbling if that's the prevailing consensus. A nice day to all--- Maynard

Just to put in a few more cents worth of my thoughts Chris. Your comment above about SETs which minimize negative performance issues being extremely expensive is absolutely wrong. It should be obvious that it doesn't cost a huge amount at all to build triode amps using excellent quality output transformers. What's wrong with an almost totally flat audio band frequency response, with low distortion, as George demonstrated in the example I cited previously? The cost of duplicating such an amp is in the hundreds, certainly not extremely expensive by audiophile standards. Sure, the performance may change incrementally as the tubes age, but is that going to be audible in most cases? Definitely not! And why do you think that extremely long warm up times are needed? It takes all of 1-2 minutes for tubes to come up to operating temperature and stabilize. I have spent a large portion of my life servicing tube type radios and TVs as well as tube type audio equipment, and have never encountered the need for hours long warm up for circuits to stabilize and perform as desired. Can you explain the basis of your assertion about this? I'm not trying to be ornery (although my wife says that such behavior is natural for me!!!), but would like to know the basis of your thinking. Regards-- Maynard

Yeah, but they're like $1k a quad, or maybe even a PAIR as I recall. Redonkulous. You are sure right about that! I read an interesting article about the factory around a year ago. Talk about hand crafting taken to the ultimate degree. The folks building these tubes are true artisans. Quality does have its price..............

These are supposed to be the best of the modern KT88s: http://www.euroaudioteam.com/en/eat-kt88-diamond-valve-000011.html

Your point is well taken which is why I recommended trying a new 6CW4 and 6AQ8. In my experience nuvistors didn't have an incredibly long service life and sometimes tested "normal" but were inadequate for the job. Mixer tubes also can test ok but need replacement. Regrettably, both of these tubes are a bit costly.

I am in Parkersburg, WV. I will likely just ship it off to http://www.radioxtuners.com/. They were recomended by forum member USNRET in another thread. He has been very satisfied with his results. I'm not familiar with them but looking at their site, they're just what you need. Another alternative is Bob Eslinger: http://www.oldradiodoc.com/main.html He's an ace at doing this stuff also and has a lifetime of experience to draw from. Good luck and be sure to post the results after you get it back!