Erik Mandaville Posted January 28, 2003 Share Posted January 28, 2003 There has been a considerable amount of information recently provided regarding a very well-made and designed 6SN7 preamplifier. It is also being offered at a price-to-parts-to-peroformance ratio that would be difficult but not impossible to beat. I would like to encourage some of you looking at tube preamplifiers to consider the possibility of building a kit preamp, where you will end up with a very capable unit, plus give you the pride of having put it together for yourself. I have no hesitation whatsoever in suggesting at least an investigation of the Bottlehead 'Foreplay' 12AU7 kit. For just a little over $100, this cathode-follow, low output impedance preamp is an absolute giant killer. It has gotten extremely good reviews from many who have built it and use it, as I did for year. It was so good, I even completely rebuilt it from scratch using a tube rectifier instead of modern SS diodes. Moreover, and much more imporantly, you will gain an insight into tube audio electronics that will help you better understand and appreciate this fantastic hobby. The kit can be built by an absolute beginner; the instruction manual is very well written; and the Bottlehead website has an excellent support forum as well. It must be a given, though, that there is the possibility of needing to rewire or re-solder a part or two, but that is where the fun and education are! And when you are done, you will have a great preamp that cost a fraction of practically anything else available. But you invested in an education that is much harder to put a price tag on. Study the schematic as you go along, and you'll begin to see how things work -- and it will start to make sense. This way, you will begin to be able to make your own, better-informed decisions regarding 'available' circuits, and perhaps might not be so easily taken on looks, alone. It's inside that counts, just like with all of us! I have no connection whatever with the Bottlehead company, and rarely post there anymore. The kit comes complete with a wood chassis (of a much younger vintage than the Pantheon -- one is paying for an outstanding preamp, not antique wood -- and an aluminum, pre-punched top plate). Once you start building, looking forward to soldering together your own preamp can get to feel like Christmas (if you happen to celebrate that -- or other exciting child-time holiday). You won't need to rely so much on the opinions of others -- which are nothing more than opinions. In short, you will know enough to make important choices and decisions on your own. More than anything else, building a relatively simple kit is just plain tons of fun! Sure it's great to get an already assembled piece that is brand new, but making something for yourself -- even when you make a mistake or two -- takes the experience to an entirely different level. And regardless of what others might say about Transcendent Sound, Bruce Rozenblit is an extraordinarily good designer, and has an equally supportive and helpful website. His 'Grounded Grid' preamp (available as a complete kit and high quality chassis for around $400, I think). There were times recently where someone posted that they very much wished they had the understanding to make sense what some other forum members might have been talking about. What a respectable thing for them to say! But have some confidence in yourself! Even if you've never picked up a soldering iron, you won't believe how easy soldering is to do -- I mean, really easy! There are also tube amp kits available for very little over $100, that would take advantage of LONG BEFORE buying a vintage, already made piece. But just if you want to learn something more about your hobby. If it doesn't matter, than it doesn't matter. I'm going to stop posting here for awhile, mainly because I want to focus on a couple of amplifier designs I have been thinking about. I don't have all the math at the tip of my finger, and it takes research to do. And although it's tons of fun to share with others here -- and many have been really helpful -- I'm going to be off here for a bit. Just for the hell of it, go check one of these things out! ...and have lots of fun! Erik Quote Link to comment Share on other sites More sharing options...
AndyKubicki Posted January 28, 2003 Share Posted January 28, 2003 Wow, I think you've said a mouthful here. I went the vintage route because I did want integrated, but will definately consider a kit in the future. I wonder if building a spreadsheet would help you with the math in your amp design... Quote Link to comment Share on other sites More sharing options...
Tom Mobley Posted January 28, 2003 Share Posted January 28, 2003 Erik, I'll build it if you will help me convert it to tube rectification. I might not use their kit, though. I live near AES in Tempe, Az, so it's easy, cheap and fast for me to get stuff from them. I have two NOS Mullard 12AU7's on hand. Can this be done with a 5AR4? I can get one of those for the asking. I'll go look at the kit, try to post back here tomorrow. Tom Quote Link to comment Share on other sites More sharing options...
ChrisK Posted January 28, 2003 Share Posted January 28, 2003 Don't know if anyone has suggested this site yet, try http://www.tubecad.com/ A fabulous site that I have been getting lost in lately. Go to the GlassWare website listed on the home page of the Tube Cad Journal. They have software that might be helpful to DIY tube audio designers. Regards, Chris Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted January 28, 2003 Author Share Posted January 28, 2003 Thanks for your responses Andy, Tom, Chris. 12AU7s are a very common tube, and a long-life, good-sounding one at that. Doubtless there may be posts that will be contrary to this, but I have built a couple of really nice sounding preamps using it. Tom: The main reason I built a tube rectified versions of the Foreplay was the experience. Tube rectifiers tend to be a bit easier on downstream components since they have a sort of built-in soft start mechanism. I had gotten to the point where everything I used my system had to be 'tubed' and I just wanted to try a tube rectifier. It worked well, and I used parts that I had on hand. I would honestly build the kit as it comes stock, first. Perhaps allow yourself to become familiar with the sound, and then maybe make one change at a time. That way you can have a much more educated (gee, I'm using that word alot tonight) idea of what is going on, and whether something changed for the better. The solid state, full-wave bridge rectifier the Foreplay uses work incredibly well, Tom. Bass response may in fact be faster and overall better than with tube rectification. The latter can always be tried later, though. I would say that a 5AR4 could be used, but is really much more robust of a tube than what the Foreplay requires. a B+ of only 157 VDC is used on the plate, so what a 5AR4 can bring to the table would be used mostly in heating heavy power resistors that would be needed to drop the voltage. I'm using a 6X4 -- again which I had on hand -- which is a more moderate rectifier, and even that is a little too much. If put together carefully and neatly, the Foreplay is remarkably transparent and good sounding. It also incorporates direct coupling between the two sections of the 12AU7, and the cathode follower output offers excellent matching with lots of amplifiers. It can drive even long lengths of interconnect very well. With sensitive speakers, you may experience a little bit of hum, but steps can be taken to fix that -- mainly building a very simple DC supply with parts from Radio Shack. Visit the Bottlehead website, Tom. People there are very helpful, and many are very, very well versed in a technical sense. Many built the inexpensive kit, and then rebuilt a hot-rodded version of it in much nicer chassis, heavier chassis plate, nicer wood, etc. The circuit is outstanding, and easily worthy of those changes. It was originally designed by George Wright. Take care, Erik Quote Link to comment Share on other sites More sharing options...
Dale W Posted January 28, 2003 Share Posted January 28, 2003 erik , this is the second run you've taken at the pantheon. Is there some underlying issues here ?? I have neither the time or intrest in building a pre-amp , not that i could'nt. You don't have to build something yourself to understand how it works or make you a better audiofile. I've read so many books on tube amps and pre-amps that i'm personally sick of the topic , not to mention that no two authors ever seem to agree on anything. The time it takes you to assemble 1 pre-amp, i can go to work and buy 2 !!! It's got nothing to do with skill or money but everything to do with " time " . I hope your not upset that some board members are using craig and jeff to build them gear , if your intent is the same then pipe up and offer some services. Theres lots of room for more players on the field. Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted January 29, 2003 Author Share Posted January 29, 2003 Hi Dale: I'm trying to finish the thread, but I'll briefly respond to your questions. If you go back and read some of the comments I have made about the Pantheon, they are all positive, and I said the JF does outstanding work, and that he is a friendly and very helpful individual. I am not taking a 'run' at the Pantheon, if you are meaning that I am criticizing it. I am simply saying that many pictures of outstanding quality (care of KH)have been provided for it, and that it is easy to get carried away on looks, alone. An interior of any electronic device has the potential of looking incredible, but unfortunately that isn't what matters. In the case of Jeff's preamp, however, I'm pretty confident that his obvious wiring skill reflects an outstanding circuit design. Of course there is nothing wrong with having someone else build one's equipment -- that should be a 'given.' It all depends on the individual, and what he or she would like to spend their time doing. My point is that there are lots of outstanding preamps available for quite a bit less, wich is NOT to say the Pantheon isn't worth its reasonable price. My intention is convey the fact that many people have the skills needed to construct a simple kit on their own -- a personal challange that will reward the builder with exceedingly good sound for an extremely modest price. I hope there is nothing wrong with my making that disclosure. I am trying to encourage a little bit of an education in audio electronics. If this isn't important to you, than that is completely fine with me. I'm sure there are others who feel the way you do, and I respect that entirely. Please be confident that I understand the question of time! Again, though...in the time it took you to log onto your computer, hop on the internet train, jump off at the Klipsch Forum station, and write a couple of paragraphs concerning an increasingly rare commodity we refer to as 'time'...you could have soldered in a couple of resistors and capacitors in a preamp kit. So, I would argue that a certain amount of time is in fact available. The issue has really more to do, I think, with the manner in which you choose to use that window of minutes or hours. If my earlier post is not of interest to you, than you should not worry about my explanation that there is very good sound available beyond the Pantheon; and that easy-to-put-together kits can be bought at a substantial savings. Again, I hope there is nothing wrong with my wanting to help save some people a little bit of money, where they can also learn something very valuable at the same time. speaking of time.................................. Erik Quote Link to comment Share on other sites More sharing options...
Dale W Posted January 29, 2003 Share Posted January 29, 2003 No worries erik, i'm not criticizing you or your view point. There is value in what you say and a great chance for some to aquire knowledge of there own gear. My comments were just about me and not meant to shoot down what you have to say. I find your posts just as intresting as kellys, craigs, deans and so on. I was fishing as much as anything, sounds like you enjoy burning a bit of tin . If so maybe you could offer some assembled kits for those how are intrested ? I've been a mechanic for 21 years and also hold several welding tickets along with a 4th and 3rd class power engineering certificate. Now that i have a young family on the go, my olny free time is spent BSING with you guys.I'm just to a point in my own life that i no longer enjoy working with my hands but quite enjoy streching my knowledge on a wide range of topics. So i appoligize if my comments sounded like a gereralization of others, i was just commenting on myself. I look forward to your future threads with intrest. DALE Quote Link to comment Share on other sites More sharing options...
sunnysal Posted January 29, 2003 Share Posted January 29, 2003 I have a double whammy that keeps me from taking the plunge to build somehting myself. time and 10 thumbs. LOL. I truly would love to build my own equipment in the future, but for now the results, cosmetically and audibly, favor a purchased unit. I really do dream of the day when retied or semi-retired I can focus on buidling some of my own equipment to add yet another facet to the audio hobby. for now I try to buy reasonably priced, great sounding (and great looking if I can find it) equipment and enjoy the music. Try to keep in touch here Erik, your contributions have always been valued by this b-boarder for one. Tony Quote Link to comment Share on other sites More sharing options...
Deang Posted January 29, 2003 Share Posted January 29, 2003 I sure wish I could understand what the hell you guys are talking about. Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted January 29, 2003 Author Share Posted January 29, 2003 Dale -- No offense taken! I totally understand. It DOES take time away from family to do this kind of stuff -- as well as to Bull-doo-doo on this forum. I grew in a family where practically all my dad did was build tube radios. I've learned lots from him, but he's the reason I learned to solder when I was 5 years old -- that's how I could spend a little time with him in his 'shack'. So I understand 100%. I usually get up on Saturday mornings at 2:30 or 3:00 (when some haven't even gone to bed yet!) in order to work on my electronics and antique clock repair hobbies. I don't want to take the daylight hours away from spending time with my wife and our children (all four of them bark and have tails!), 'cause I watched my mom and dad's relationship fall apart because of his doing nothing but sending out 'CQ' messages in his home built radios and receivers. Geez....I just heard my pot of spaghetti (how the hell is spagetti spelled???) boil over........................ Take care you all and enjoy! In Friendship and with Regards, Erik Quote Link to comment Share on other sites More sharing options...
dkbks Posted January 29, 2003 Share Posted January 29, 2003 Thanks, guys, for an interesting thread and the leads to www.bottlehead.com/ and tubecad.com. Hadn't known about these and Bottlehead looks especially good. Used to solder together radios and ham gear a number of year ago & these might get me involved again. Quote Link to comment Share on other sites More sharing options...
sprocket Posted January 29, 2003 Share Posted January 29, 2003 Erik Great post regarding the Bottlehead Foreplay. I've heard about half a dozen differently configured Forplay preamps from completely stock to well tweked. They all perform surprisingly well. There are meetings here in New England and throughout the country (check the Bottlehead Fourm) for tube amp fans where kit builders and builders from scratch show their creations. When I have attended, I have found enthusiastic and helpful folks and lots of cool gear. Dale, the Forplay kit is a medium skill level kit and could be assembled in a day. Many upgrades are also available from www.bottlehead.com directly and also from the members of the Bottlehead forum. Best of all their probucts are inexpensive and yet give a full measure of the tube/SET experience. RB Quote Link to comment Share on other sites More sharing options...
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