tube fanatic

I had planned on a better antenna. I will make sure I buy one with good isolation charicteristics. I was pretty sure it was either the FM front end or the multiplex circuitry. I am the type of guy who really enjoys learning. I learn by doing. I am content listening to mono, but I really want to know why she's only fireing on 7 cylinders. I had an electronics repair shop test all the tubes and they tested OK. I don't know how good the tester he used was, or if it was properly calibrated. He said an old timer gave it to him, and he only uses it occasionally. I am going to get a better antenna, and we can see if that extra signal helps. While I was cleaning potentiometers, I sprayed those fins. They didn't look at all dusty. This receiver is actually very clean. Nicely said. In answer to my question above, the consensus seems to be signal improvement( in case the side bands aren't quite strong enough), FM front end alignment, and then multiplex alignment. I can easily do the antenna part. That may be the only problem. As for the rest, I would have to build, buy or borrow an FM signal generator, an Oscilloscope and a VTVM at the very least. Or try to find a qualified tech in my little town. This is not the type of equipment on which to learn how to do an FM stereo alignment! You will need to buy (building one is an extremely advanced project) an FM multiplex/sweep generator. That isn't going to be inexpensive. In addition, you will need to have a good understanding of how to use/interpret what you see on the 'scope. Where are you located? I may be able to help you find someone qualified to do this for you.

I haven't heard either of the bookshelf speakers. I use RF-15s which are a predecessor of the RF-52 II and they are absolutely amazing in terms of smoothness, imaging, and bass output. A description of the room in which they are used is in my profile. Given the size of your room, either speaker type should work just fine (the bookshelf speakers will, of course, need to be elevated on stands.) So, it will probably be more a decision about appearance and location than anything else.

So what SET amplifier is Pass making these days? Is he currently making any tube amp? What I saw were solid state designs, mostly FET based, both single ended and PP. Did I miss something? Yes- i.e. design preference. Pass prefers/likes solid state. I prefer tubes to solid state. Why does Craig build tube amps and not solid state amps? I don't see the relevance of your statement Don.

The problem is not in the preamp or amplifier sections. To troubleshoot and properly align the front end and multiplex circuitry you need to have some fairly sophisticated test equipment. Unless you are experienced in doing this, I suggest that you refer it to a qualified repair person. It's easy to mess things up very quickly! That said, you could try replacing the 6CW4 and 6AQ8 in the front end. Even though the stereo light is illuminated, you may still not have sufficient signal to get a really good lock on the station.

Bingo ...I'm thinking that there are a lot of garage-shop and slightly better tube electronics shops that honestly believe that they are fully set up to produce high quality, tested, and well-designed tube amps and preamps, etc., but they're really not even though they will tell you that they are. I really don't see any large manufacturing businesses dealing in tube electronics, such as the big multinational U.S. and Japanese firms, although I haven't been looking thoroughly at this market since my Bottlehead experience. The best that I've read about is the Silver Seven series from Bob Carver, but few can actually afford those exquisite units--even used--and they have a lot of power headroom that I don't think that I need to drive my 110 dB/W TAD drivers in a biamped configuration. Some of the issues that I've read about regarding the products from these type of mom-and-pop tube shops (and I apologize in advance if I step on anyone's toes here, because I know that I probably will...), is that their products are not being designed and tested using any kind on large-business standards or "regression test checks" with other commonly used interfacing hi-fi gear, and therefore only work under certain conditions, both upstream and downstream of the amp or preamp in question. Most of the product testing is occuring in beta, i.e., by paying customers, which is a really bad business model for hardware for the customers (but not the business owners), IMHO. And these tiny firms often do not stand behind their gear in terms of money-back guarantees if the customer is not satisfied. Note that First Watt/Reno Audio does have a money-back guarantee. So, you might get what you pay for with these tube designs, but you are actually taking more than a bit of a risk. I took the risk and lost. Worst than that, I've got people trying to tell me that I'm not "using them correctly". Please don't ever try to lay that kind of line on me: it's quite insulting. No offense taken to any of our discussions on this subject Chris. I thoroughly enjoy point/counterpoint conversations on almost any topic. In regard to the garage shop and mom/pop tube equipment builders, much depends on the individual business philosophy. Although not formally "in the business" at this point, I still do design/build amps and sundry other tube stuff for friends, friends of friends, etc. But, in almost all cases they get to hear the amps in their system before buying since I keep many prototypes of all kinds on hand for just that purpose. Using the prototype for say a week gives folks an ample opportunity to "try before you buy." When I build a clone of the prototype they have the assurance of knowing exactly how it will sound while getting to choose the kind of enclosure or chassis that they want and so on. Yes, on occasion someone finds some tubes at a garage sale or hamfest and asks me to build an amp around them; however it's with the understanding that they are taking a bit of a gamble since the exact sound won't be known until it's in their system. Usually, it works out fine. There are people all over the country who operate small, custom tube amp businesses whether they are for home audio systems or guitar enthusiasts. Many do terrific work and build to "battleship" standards. So, one really can't generalize. And, from what I've read, a perfect example of what I'm saying is the forum's own Craig! In the time I've been on here, no one has ever had anything but high praise for his amplifiers which some have apparently purchased without even hearing them. Regards-- Maynard

Great article which I'll show to some of my inveterate push-pull amp designer buddies with whom I constantly argue the virtues of single ended designs. I certainly agree with the statement, "As a result of its single-ended nature, the harmonic content of air is primarily 2nd order, and most of the distortion of a single tone is second harmonic. Air's distortion characteristic is monotonic, which is to say its distortion products decrease smoothly as the acoustic level decreases." Makes a great case for near field listening using a SET!

It's difficult for someone to tell you which speakers you will prefer. One consideration, however, is where you are going to position them. The RF42 II and RF52 II are rear ported. To get a good soundstage, etc, they need to be positioned 1-2 feet from the wall behind them. The RB61 II and RB81 II are front ported which allows positioning against the wall if necessary. Have you any way to audition the speakers before you purchase them?

It would be helpful if you describe your listening room (size, listening position relative to the speakers, furniture, carpets, etc.), type of music you listen to, and how loudly you listen. All of this will help determine how much power you will need which will, of course, determine the price range for satisfying that requirement.

At some point, I believe that engineers will simply say , and walk out of the room, no matter what the PC answer is.My observation: If you want soft clipping, buy a SET (personally, I don't want clipping at all, and I don't have to put up with clipping). If you like listening to even-order harmonics that aren't in the source material, you can buy a synthesizer that does that (such as an Aphex Aural Exciter), or you can buy a SET. If you want a reverb unit, you can buy a reverb unit, or you can buy a high-output-impedance SET. If you want EQ, you can buy an active digital crossover, or an EQ unit, or if you like the "canned EQ" that a SET brings (i.e., high and low end roll-off), you can buy a SET. If you want all of these "features" at once, then buy a SET: it might be cheaper (...or it might not be...). It also glows in the dark, heats the room, and gives you something to do (rolling tubes) when you are looking for something to do with your spare time... ...but please don't call it "high fidelity", because it isn't...it's a sound synthesizer/processor that has a small amount of forward loop gain. Chris Wow Chris, you sure don't like SETs!!!!! What's your take on people who use vintage integrated amps and make very definite use of the tone controls to create the sound that they want (like severely rolling off the top end to make modern recordings listenable through their K-horns)? I don't see that there's much difference. And as far as the distortion of SETs, did you look at the measurements that George came up with on those budget transformers (http://www.tubelab.com/BudgetOPT.htm)? That's more in line with my experience and certainly not anywhere in the range of being unacceptable imo. Cheers-- Maynard

Hey Pat! These are equalization standards which were used for playback in the old days. Here's a whole history of the systems: http://en.wikipedia.org/wiki/RIAA_equalization

This is a "rubber yardstick" as PWK coined the term, and I'm a little bothered by it as being a bit cavalier... Chris The "rubber yardstick" term has also been debated since before I became involved. It brings to mind many blind listening tests in which I participated where solid state amps with vanishingly low distortion were auditioned against tube amps with more dubious distortion figures. What would be your conclusion when the listeners kept choosing the higher distortion tube amps as having the best sound? Why do so many solid state amps, including many with superb measured performance, sound like crap? As far as triode amps having rotten distortion figures, take a look at some of the budget output transformer measurements done by Tubelab some years back when driven by a 300B: http://www.tubelab.com/BudgetOPT.htm Makes you wonder what all the fuss is about. Regrettably, I no longer have my journal in which I had recorded the data for many of the designs I implemented over the years (thanks to Hurricane Floyd attacking my normally dry basement!), or I could present definitive data on many of the single ended designs that I've utilized. In any event, these questions will be debated indefinitely imho and unless someone comes up with a way to quantify exactly what the brain is doing when processing auditory information, there will be no answer. Maynard

I've seen examples of tube amps with 15-30 Ohm output impedance, all of them are SET amps with no feedback. I've never encountered output impedances that high! The questions about why SET amps do what they do have been raging for longer than I've been in the field (and that's roughly 5 decades!) It brings to mind a review of the Cary 300B which Stereophile ran back in the 90s (just found it- here's the link: http://www.stereophile.com/integratedamps/398) In spite of the horrible measurements, the amp sounded wonderful. If you get the chance, read the whole review, and especially take a good look at the measurements. I can't explain why so many SET amps sound amazing. I've designed/built dozens of SETs (without any negative feedback), and SEPs (with enough negative feedback to keep the distortion very low) for people over the years and frankly, given the right choice of speaker, I prefer the sound of the SETs. It's a question which is unlikely to ever be answered and gives a great deal of credence to the often quoted statement, "if it sounds good to you, it is good!"

never have I seen such beauty!!! Here's a review of the CS300 from Stereophile: http://www.stereophile.com/content/leben-cs300-integrated-amplifier

It isn't unusual for SET amps, which typically don't use any negative feedback, to have an output impedance of 2 or 3 ohms. With speakers which have a large variation in impedance across the audio band this is potentially significant. I say potentially because much depends on how loudly you listen (which determines just how much voltage the amp is called upon to produce.) Adding some negative feedback can reduce the output impedance thereby creating a better match with such speakers. Many users of single ended tube amps enjoy listening with single driver speakers which have a fairly constant impedance across the audio band. My experience with SETs and K-horns, Cornwalls, and La Scalas is that they work quite well if the levels at which they are listened to don't tax the amp too heavily. Under those conditions the sound they produce can be magical in terms of soundstage size, imaging/detail, and the bass, while not the same as what is produced by a solid state amp, is full and rich without being boomy or in any way objectionable.

This part of NJ is one of the most affluent areas in the country (wish I could say that I fit in, but I'm just one of the old country folk from days gone by.) But, new home construction is virtually dead and resales aren't moving unless they are being given away for far less than the assessed value. The box stores (Lowes, Home Depot, Walmart) are doing so-so. Restaurants, however, are packed to the rafters every day at lunch time and every evening. And I'm talking about every parking spot occupied.

How about insufficient power for many applications? Don, you have taken me out of context. I was answering the statement about SETs being lacking in bass. The required power, or actually voltage, for a given spl or visceral impact is another matter entirely. The solution which Mr. Bryan implemented is a fine way to have the best of both worlds.

Any SET amp which doesn't make bass isn't using the proper output transformers (the same could be said about single ended pentodes also.) There's nothing about SET design itself which prevents amplification of bass frequencies.

Yes, I've seen them before. Truly amazing and well worth seeing again as it has been many years! Thanks for posting it- very enjoyable!!!

Neither did the guy "singing" it apparently!!! Considering that my young relative likes it, perhaps that explains why high end audio is of no interest to most people in their twenties. Can you imagine listening to that on K-horns at 100+ db?

This link was just sent to me by a relative in her twenties (she thinks its cool.) Not sure what to make of it but couldn't resist contrasting it with Marty's excellent selection!

Is it an S-5000 or S-5000II. I ask because the latter uses fairly expensive output tubes. The asking price is reasonable if the amp is in really good cosmetic shape and if it is truly and fully restored.

While amps like the miniwatt will get you started in the realm of tube amplifiers, it's not likely to compare with a properly restored vintage amp. If you have the knowledge to do the restoration yourself, that's a good way to proceed. Or, if you can go for a little more money, the Decware Zen is a proven design which has gotten extremely good press over the years both in terms of its sound and its reliability. Where are you located? http://www.decware.com/newsite/SE84C.htm

In the context of the power consumption of the typical home, a tube amp represents a very small percentage which can be easily recovered by simply shutting off the lights in unoccupied rooms and so on. It's not something worth worrying about.

Thanks! I'll try Firelands Radio this week. I'm not too far from Sandusky. I forgot that Dayton is in another part of the state when I posted Tom's site!!! Glad to be of help. Most of the antique radio repairers/restorers that I know also do the same for tube amps. After all, a radio is simply a "tuner" coupled to an audio amplifier. They are a terrific source for amplifier work on a local level, and their work is often above and beyond what is needed (some of the guys even open up the old paper caps, install modern replacements inside, and reseal them to preserve the original underchassis appearance!)

http://tomsradiorepair.bizland.com/ http://www.firelandsradios.com/