Erik Mandaville

I second Kelly's apology. I feel I was the one who compromised proper forum etiquette. It won't happen again!

Due to the inappropriate nature of this post for a public forum, it has been romoved. I feel I was the one who compromised proper forum etiquette. It won't happen again!

Sure! www.bottlehead.com ...maybe wait until you're at home to have a good look!

Hi Tony: You CAN build one of these! You must understand that it is as easy as following a recipe for beef stew! Once you know how to solder (just try it, and you'll see how simple it is), all you do is follow the steps in a very well written construction manual. It's kind of like a 'paint-by-numbers' affair, where you're told exactly what needs to be connected where. check off each step as you go along, and you'd be done in a couple of days, if not sooner! I'm more than happy to help any way I can, from building to testing voltages (that's where you have to be a bit more careful), etc. Erik

Feel much better soon, Justin!

Well, the cost of the preamp kit has gone up a bit since I last looked at the price. The kit is now selling for $149. Still a bargain, nevertheless!

I appreciate your way of offering some comment on this subject, RB. Thanks for including the websites addresses for the Bottlehead sits, as well. In all my bantering (and attempt at defending), I managed to forget to include that information for those forum members who think they might like to have a look. By the way, there are other products available, such as a number of SET amplifiers, from the Bottlehead corporation. Athough highly regarded, some haven't gotten quite the same reviews as perhaps the Moondogs and George Wright amps. The Moondogs are pretty tough to beat, but they are no longer sold as kits. As you all know, however, Welborne Labs is offering a new line of amps and preamps -- the 'ultrapth' output equipment. If you are able to afford more than the Foreplay, and desire subjectively better parts, chassis, etc., Welborne Labs sells products that are built like tanks! Very good looking, as well! I would venture to say, though, that my experience is that the Bottlehead site is perhaps a bit better in terms of feedback and technical assistance. That notwithstanding, It can't be denied that Ron Welborne affers products for the DIYer that are very likely at or near the top. I think the Transcendent Sound preamplifier (the 'Grounded-Grid') is around $400 for the kit. I know a couple of people who built the GG from scratch, and they are extremely happy with its performance. They say it's incredibly fast and agile, with astonishing clarity and detail. The kit GG some with a very sturdy chassis, and uses PCB circuit construction. It is also said to be very quiet due to the use of isolation transformers, which would be a benefit to very efficient horn speakers such as....let me think....what company hosts this forum again.....???? oh yeah, Klipsch! And then there is AES, which sold my current preamp (which I like very, very much)the AE-1. Erik gee....having a bad cold and staying at home from work for a day does have some small advantages!

Kelly: Isn't this pretty obvious??? The Foreplay doesn't cost anywhere near what you are comparing it to. But you're are really missing the point, which surprises me. You have admitted that you haven't gotten into any kit-building, and you are one of the people I have in mind as being among those who might benefit from the process. The Foreplay wasn't designed as an end-in-itself preamplifier. Think what you will about 12AU7 tubes, it will not change the fact that they are extremely good audio tubes. And I'll say this again: My point in bringing the Foreplay into the picture has more to do with the process than the product. For such a very small cost, one is investing in what can lead to a life-long enjoyment of DIY tube audio. Buying a pre-built component is absolutely, unquestionably, undeniably a perfectly valid and legitimate thing to do -- especially if one doesn't have the time (although there are wasy to find the time if one might take a close look at how one spends a very significant amount of it...). My mentioning the Foreplay and Bruce Rozenblit's designs was geared toward those who are interested enough in learning more about electronics and vacuum tube technology -- both historical and contemporary -- to maybe have a 'go' at building and constructing a piece of very decent sounding equipment for a very modest cost. The Foreplay does not come with a pile of fancy-*** resistors and insanely priced capacitors. It is a very basic design, that encourages and allows the individual user/builder to implement changes on his or her own -- and learn from the process of undertaking those midifactions, as good or bad as they may turn out to be. I don't have the slightest doubt that JF's Pantheon is a first-rate design. My point was that there were several posts made by genuinely inquisitive forum members who expressed an interest or a desire in gaining the ability to build an audio kit. Jean-Francois' preamp is not sold as a kit (is it?), so I tried to think of some designs of which I am familiar that I could suggest to those curious few. Nothing will change the fact that the Bottlehead Foreplay and Transcendent Sound Ground Grid preamplifiers are truly excellent ways to begin the joy and pride that can come from building something for one's self. There are other kits available, but those I mentioned are the only ones I can speak about from experience. What one gets for a rounded figure of $100 is very much a giant killer! Know why? ...but wait, you already mentioned that you had doubts about that. So let me explain: Once those two 12AU7s are glowing and making music that would have normally cost alot more to obtain, the person sitting there listening in the dark can smile and think (or even say out loud!)"Cool! I built that myself!" It's a neat feeling, and I hope you get to experience it sometime. Erik

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

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

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

It's been a long day...

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

I see that now, Kelly. JF just sent one schematic, which was kind of him to do. Though he may not post here, I was confident you would provide some extra information on his preamp.

ummmmmmmmmmmm.... I was going by one of the emails he sent me. I haven't read very much about this preamp, Kelly.

Hi Leo: Yeah, the 'real' voltage on the 2A3 is taken between the plate and cathode. On my stock moondogs, the plate to ground voltage was around 375 VDC, -50 of that for the cathode. RCA Receiving Tube Manual specs on the 2A3 is 250 max. Modern 2A3s like the Sovteks and the KR (EXPENSIVE!) can handle considerably higher voltages than that. Some Moondog owner builders (with the designer approval)have bypassed the resistor between the big power supply electrolytic (R13, I think)with a wire lead, when using the KR tubes. The problem I have with that is the fact that ALL voltages, including those for the plates of the 6SN7s branch off that main B+ line. So if the B+ goes up substantially higher by bypassing that resistor, than all the voltages for the other stages go up, as well. Thanks for that reminder though, Leo! I use a 5Y3 rectifier in my amps which, while possibly not as visually appealing as the big bottle GZ37, easily supplies the needs of the tubes in this amplifier. When I lowered the 2A3 plate voltage, I changed some of the values of the resistors in the other stages in order to bring them back to the voltages on the schematic. I'm now running the Sovteks at about 275 VDC. On that C4 capacitor, common higher voltages for that type of capacitor is 400 and 600 VDC. I think, too, that one of the points of this ultrapath capacitor (a Ron Welborne term, which fits!), is that it assists in filtering away power potential influx of power supply noise. When connected to ground in the conventional cathode bypass configuration, the signal path is returned to the power supply, vs the opt in the ultrpath circuit. I'll let you know how the DC 2A3 filament supply experiment goes. It should be a fairly inexpensive thing to do! I want to use 10,000mfd filter capacitors which I will have to order. See ya! erik

Hey, Jean-Francois! Very beautiful work, and a ground buss that is great! But, I thought you said you don't use cathode bypass capacitors?? Regards, Erik

Hi Leo: I had a concern about the C4 voltage rating, as well. Mine is rated for 250 volts, and I have my B+ running just a bit over 300 VDC. I honestly don't believe there would be a problem with this, although it might be a good thing to get a capacitor with a higher voltage rating. The DRD ultrapath amp. shown in the schematic I mentioned to you has an oil capacitor connected between the 2A3 cathode and OPT. The output tube is a 300B and B+ voltage is 700VDC. The capacitor used in the ultrapath connection (for lack of a better way to describe it)is rated for 600VDC, so this encourages my thinking that capacitor specs are conservatively rated for a healthy safety margin. I read somewhere that most modern polycaps can withstand twice their voltage rating. Still, I think you are right concerning this issue. You know, I sometimes wish I would just stop experimenting! Taking out C5 was a definite improvement, and maybe I should just forget developing this utlrapath thing further. I'm just really curious about learning about the application and theory. I love a very detailed presentation (which does not mean dry and difficult to listen to), and if this helps bring more of that characteristic out, than I'm for it. Thanks for your feedback, Leo, and for taking the time to discuss this with me. Erik

Hey, Deang: I think I remember Al K. mentioning something about that break-in issue!

Hi, Leo: I've got to get out the door to work this a.m., but I thought you might be interested in this -- and wanted to at least reply briefly. Your understanding if similar to my own, actually. I think your reference to 'v+' is actually B+...is that correct? The thing with the 'actual' DRD amp and ultrapath output is that the output tube filaments use DC on the filaments, and the big capacitor (C4 on the Moondogs)between the OPT and cathode is connected to the minus side of the DC supply -- so polarity is likely important. I'm going to incorporate a DC supply (see above post)this coming weekend, which is something I've wanted to try for awhile, anyway. I tell you, the more I get into this and try to learn, the more I realize how little I really know! Talk to you soon, Erik

This is interesting, for sure! I'm hearing valves on oboes and clarinets slapping closed, which I don't remember hearing before. All my voltages are within about 5% of the schematic specs, so nothing is getting undue blasts of voltage and current. For those interested, I'll report as this develops and break-in continues. I'm honestly starting to believe that people are the things that need to 'break-in' and get used to component/cable/wire changes -- not the passive devices! Yeah, I know lots would disagree... Erik

Thanks for you feedback, Leo. Well, I've been studying the schematic for Jack Eliano's DR amp., which I've had since it was published in Vacuum Tube Valley sometime ago. I even started to slowly purchase parts to build it, but ran out of funds for four expensive transformers -- which is basically the primary cost for the project, of course. The secondaries for the DRD OPTs are, according to Jack E's design, also wound with silver wire, and I didn't even bother to ask the price of those. I was going to try it with copper, which would have been cheaper, but probably not as 'detailed'. So I started thinking of ways to possibly apply some of the circuit design into the Moondog, which as you know is a fairly conventional SET circuit. And a good one it is, too. I think Ron W. mentioned somewhere that he used two 6SN7s in the input and driver stages because that's what the chassis plate (used for other amps, as well)was already set up for. This is getting off the point, though. In general, the Ultrapath approach (I'm sure you already know this!)returns the signal path from the OPT to cathode v.s. the more usually-seen power supply to cathode. On the Moondog, it looks as though the cathode bias is incorporated into the hum/null pot circuit. Since a large poly cap is used in that position rather than an electrolytic, it might be simple as removing the grounded end of that capacitor and connecting it the juncture of T2 and R8. I was looking at this late last night when I was tired, and I'm going to study it some more in a bit -- the whole thing was sort of a fleeting idea that I thought might be possible. On top of this, the DRD amp uses rectified AC on the 300B filmts., and that would be a very quick thing to incorporate into the the Moondog, as well. This would involve the addition of a small filament transformer, which could be installed inside the amp on the side wall -- with primaries wired in parallel with those of the main power transformer. A simple full-wave bridge and subsequent filter capacitor (say a 4,700mfd. or two paralleled)and a dropping resistor are all that would be needed to complete the job -- and almost all the parts can be bought at Radio Shack. As you can see, the idea is not tightend up yet, but just a thought right now. I tell you, there are times I wish I had a scope where I could see, as well as hear what was going on! My pop in AZ. has three of those things, and maybe I can get him to sell me one! Anyway, thanks again for your focused work on that C5, Leo. The change for me has been a very positive one. Time to get the other side finished, so I can listen to music the rest of the day! I have the Glenn Gould Goldberg CD, too. The guitar version By Kurt R. is very, very different! Regards, Erik

The capacitor I'm talking about is C5 on the Moondog schematic. It is called a 'bypass' capacitor because it is installed across the cathode resistor, which is referenced to ground. For anyone else who may read and be at least slightly interested, Jean-Francois L., who designs and build the recently profiled Pantheon preamp, encouraged this modification heartily. Thanks to him, as well! This is such a simple modification, which won't hurt the amp, but may reduce bass response for some, depending on listening tastes and preferences. By the way, I type really fast, and sometimes repeat words...so I apologize for combining the the wheat and chaf together! Erik

Caps off to Leok! I completed one side of the cathode bypass early this morning. This gets to be kind of a long story, but in brief, the change required removal of the volume control I installed previously on the the Moondogs. Gain went down slightly after the cap was taken out, and things were just much better with the volume pot out. The signal now sees a fixed input of 100k (referenced to ground), which is in front of a 1K grid stopper to the 6SN7 grid. With the volume control (100k log taper), the output impedance to the input stage was probably around 60k, or so, which assisted in making the amp. less sensitive. For sake of comparison, the volume control on the other amp. is still in place. The difference with the cathode bypassed vs unbypassed is considerable -- so far for the better for me. There is a 'jump factor' and clarity that is not nearly so prominant in the amplifier still using the bypass capacitor. If I can use certain art terminology to describe the difference: presentation without bypassing has excellent contrasts in value -- meaning dynamic changes are more pronounced. High frequency characteristics are, gosh, just really wonderful -- like highlights of sunlit crystal in a Vermeer painting. Classical guitar was especially note-worthy. I listened to performancs throughout the day by Julian Bream, Pepe Romero, and an absolute knockout (all of you should get this CD if you don't have it!): Kurt Rodermar's guitar transcription of Bach's Goldberg Variations (Sony Classical). This last CD is incredibly good played through the La Scalas. The piano version of this great work is good but the guitar version is to me more engaging. Since piano is obviously capable of lower octaves than standard 6 string guitar, Rodermar had guitars custom built to be able to hit the lower notes. Please get this if you don't have it! Driving my Lowther horns, the modified cathode circuit maybe sounds just a bit thinner, but hardly so. Through the La Scalas, I don't notice any lack of bass response the the capacitor taken out. In fact, gain has gone up considerably due to the removal of the volume control; so much so, that I'm going to have to take the 250K pot out and replace it with either 100 or 50 k ohms. Alright, I'll close my mouth on this now. If you've got Moondogs, you might want to give this a try. I appreciate the work Leo did on this, and his sharing it with all of us! How does the idea of an Ultrapath Moondog sound?! Erik

"Beautiful"??? Another example of how our aesthetic sensibilities strongly differ.