Erik Mandaville

Bruce: Well, I suspect I should qualify that 'classic' evaluation. To me they are very simple, straightforward designs (meaning of course the circuit), and do not seem to get old in terms of looks. I considered selling mine at one point, and held back knowing I would regret it later if I did. On top of that, yours also have the MQ transformers, and those seem to less common than those with ElectraPrint power and OPTs. I have been running all filaments with AC, too. I don't know why I like the sonic results of that, but I do -- maybe one of those 'mental' things. Maybe I just like the idea of it, but it does sound good. Phillip: Sure, I'd be happy to share some photos via email. The pink dyna 70 was actually something I jokingly suggested to Will, and the next thing I knew he had one built -- with pink powder coat. I imagine the Edgar Horns are very nice, indeed! Erik

Neat job! There a very nice people at Decware. As Mike said, this circuit is kind of classic, and no doubt similar to the one I built below. I wasn't happy with the factory wiring layout in the instructions, so rebuilt entirely. Uses two 6BQ5s single-ended and a 12AX7. I really like your wooden chassis, though! It reminds me of the old bread board Atwater Kent Radios from the very early years. The little amp shown is now my headphone amplifier, although it sounds huge through the Klipschorns, and in fact was once reviewed with Klipschorns. Erik

And Bruce: Wish I could take credit for the faceplate. My only contributions to it were the holes I punched for the RCA jacks. I think it's neat you still have the Moondogs, by the way. I'll never sell mine; they are classics! Erik

Or these sort of Bauhaus-tech Dynaco MK III interpretations. It's essentially the stock version, although I have seen for years modifications that use triodes in the front end, which many like, and I'm sure also sound very good. These are different from other MKIII he's done, which are also aesthetically, IMO, very appealing.

I actually do know how to separate paragraphs -- don't know why it's not showing as such when I post. Here's one of Will's more brightly colored amps. Erik

Hi, Phillip: Sure, no problem at all on the pictures. Credit on the amplifier color scheme and face plate belong to Will, However (though I did tell him I preferred something less bright than the picture of another one of his scratch-built amps shown below -- which some people love, of course) The powder coating is considerably more durable than spray paint of any kind, and is extremely resistant to abrasion and scratching. The modifications I did had to do with relocating the RCA jacks to the front, and changing the positions of the power switch, LED, and engraved logo. The Lowthers are in the Medallion II cabinets from Lowther America. I purchased them in unbuilt form, along with the Moondog kit from Welborne Labs in the late 90's. As shown, efficiency has been measured to be in the 103 to 106dBs (driver dependent). I have the PM2As. They are often described as 'full-range,' although I think that term might be just a bit optimistic. Like any component, despite associated measured response, they have their strengths and weaknesses. For much of the music we have, they are astonishingly good -- electrostatic like midrange, but rolled off somewhat at the frequency extremes. A newer version of this same speaker, the Medallion III, includes a very fast tweeter, which I'm sure helps the HF response. I've used several different high efficiency tweeters on top of the cabinets, but none that were ever satisfactory. Having tried a couple of subwoofers, I found a 10" sealed design from Parts Express that seems to integrate quite well. I had tried our larger SVS sub, and it seemed to be alright for awhile, but the more I listened, the more I began to sense a slight disconnect between the two. What I like most about these speakers, and something that is unlike any others we own, is the fact that they don't use a crossover. They have remarkable speed and presence, but do, in fact, have a mild coloration due to the horn loading. It's a coloration I'm willing to accept, just as every single component -- CD, vinyl, tube, transistor, capacitor, resistor, etc., -- contributes subtle alterations to musical signals. The game for me has been finding which colorations are my cup of tea and which are not. Sometimes the less expensive whatever-it-happened-to-be turned out to be what sounded 'right' in a given design or circuit. I choose the rightness of sound over everything else. This ST70 is not configured for triode operation, but that's an easy modification. Here's one of Will's bright yellow amps just for fun: Regards, Erik

And a closeup of the amplifier: You'll see other Dyna 70s of his with the power switch on the front and the LED placed differently. Shown were changes I made for front installation of the jacks. Erik

Hi, Phillip: Apologies for this slightly tardy picture, but I was just enjoying listening to music yesterday. This is a shot of a slightly modified version of Will's Dynaco ST 70 rebuild. I made some changes which mainly had to do with punching holes in the powder-coated faceplate for front installation of the RCA jacks. I have always tried, if possible, to install jacks as close to the input stage as possible, but that's just been my own M.O., as it were. I took advantage of the subsequent available hole to the rear of the chassis (where the RCAs had been) for another pair of binding posts to make use of the 16 ohm tap on the output transformer. The noise floor of this amp is extremely low, even with the very efficient Lowther horns seen below. These speakers are even more revealing of the quality of upstream components than the Klipschorns, and I found a very interesting modification of the input ground arrangement that resulted in a wonderfully quiet backdrop for music. So. Here is just one of Will's MANY Dynaco interpretations: Have a good Sunday, Erik

Brian: Despite certain advantages (which are ultimately also subjective in terms of perceived improvements) afforded by the use of higher order passive crossovers, the problem one may encounter has to do with the associated insertion losses. This has simply to do with the fact that higher order crossovers have a greater number of passive components -- coils (aka inductors) and capacitors. Each of those parts contribute a certain 'obstructions' for the amplifier; and lower powered amps such as the Moondogs (I know, I have a pair) are less able to overcome the difficult load of more complex crossovers because of power limitations. They simply do not have much headroom to work with. That's the reason many SET owners have found very good results with extremely efficient single-drivers in Lowther or Fostex-based horn, bass reflex, or tuned pipe designs. Or, Klipsch Heritage. The La Scalas I had were driven beautifully well by a pair of parallel-feed amplifiers I built some years ago. In fact, I think that system provided some of the best sound we have had here. However, the crossovers used were very simple in order to permit a better power transfer between amp and speaker. See picture below of this system. One thing I believe should be mentioned about the Moondogs or other amps that use directly AC heated triodes has to do with the fact that they contribute a small amount of 60Hz hum. This is ameliorated somewhat by the use of a hum balance potentiometer, but with very quiet program material, it's possible this inherent component of AC heated triodes may be bothersome. This is a known and well-documented characteristic of this type of amplifier, and it's equally well-known and documented that push-pull output amplifiers are inherently more quiet in this respect. The Moondogs are superb 2A3 amplifiers, but as Kevin mentioned above, they may not be the best choice for everyone.

Jim: I'm sure your dad is very busy -- understood there. But gosh, what a true talent he is. The radio he did for us is a prized possession -- along with a very similar and very tiny SS version of something very similar my dad made, which runs off of a small battery pack. They are both so different, and both really cool. I'm sure he'll be able to check it out. The symptoms you describe could be many things, but are not serious. Things happen in the best of cases. Phillip: Your observation about La Scalas in the near(er) field is interesting. Something I have thought about the big Klipsch Heritage designs has to do with just that point -- listening in a smaller room at lower to moderate levels. I have to say that that 'personality trait' of the speaker is one of the aspects we particularly appreciate: performance at lower volume levels is great, IMO. The monitors pictured above tend to need some energy/wattage to get them going, while both LaScalas and Klipschorns have a sort of hair-trigger-like sensitivity that enables them to perform very well with such small amounts of power. In a smaller room a good SET amp can be incredibly good. I have an interesting VTV article, which includes an interview with PWK as well as a review of the K-horn coupled to small (meaning power) amplifiers. As such the speaker was rated very highly. I have to say, though, that the first Baldwin I had here absolutely fit wonderfully with Klipschorns and Heresies alike. When others say single-ended amps are dull, lifeless, distorted, etc., they are offering their own opinion -- which is totally fair. That description is not shared by others, which again is yet just another opinion. I suspect what's nice about the Baldwin is that it works well at both higher and lower volumes, and, perhaps moreover, is not expensive to experiment with in terms of input and output stage tube rolling. Many of the 2A3s I have for my SET amps cost more than the entire Baldwin (or Dynaco ST70 amplifier -- complete WITH tubes). I could be very happy with another pair of La Scalas. The seated listening height for me is actually better than the Klipschorns. Take care, Erik

Hi, Jim! Have you tried just checking/cleaning the tube sockets and pins? Make sure high voltage has drained off before you do anything -- and give that a try. If that doesn't help, and you still need help, I'd be happy to have a look for you. We'd consider this warranty work! ....no getting away from the fact that those amps are kind of heavy to ship, though. Erik

I agree with Bruce as well. I've used SET amps for many years, and really like what they can do with the right speakers (right = very efficient, appropriate impedance). I also do most listening at low to moderate levels, although I have driven my Moth integrated 2A3 amp into clipping with demanding source material played at high volume. I built my pair of Moondogs in the late 90s, and have also configured them for use with the 300B triode. I suspect I didn't really perceive that much of a difference between the 300B and 2A3 in terms of power, but both can sound good with the Klipschorns -- or even Heresies. Moondogs are IMO classic 2A3 single-ended amps, but it would be good to try something similar, if at all possible, to see if they are right for you. If not, nothing lost; there are so many amplifiers available that would be worth considering. As others have mentioned, there are some really outstanding push-pull amplifiers. For home theater I use 30 watts/channel, and it is much better for dynamics of movie soundtracks. One consideration with an SET amp has to do with the loudspeaker crossover. Many have found good results with more simple, lower order designs, just because of the lower insertion losses. Very high order networks, which require many passive parts, have not, in my experience, been particularly well-suited to amps in the 1.5 - 8 watt power range. Again, that's been my experience. Everyone is different. Have fun, Erik

Hi, Phillip: Absolutely no apology needed regarding pictures. It was quite awhile before I ever posted any at all, and it was actually through help from others on this forum that that started happening. My slow brain understands vacuum tubes and transformers much better than computers, although I learn everyday how little I actually know about the former! Okay, I think I remember the Edgar system you have. Thanks for the information on that. La Scalas were the first pair of Klipsch Heritage we owned, and I sold those to upgrade (if that's the most suitable term) to the Klipschorns. With the 2A3 amps I had at the time, the La Scalas were awesome, though they didn't hit dungeon depths in the bass dept. I actually think they were among the best sound overall that we have had here. I've actually considered selling the Klipschorns for another pair of La Scalas, as odd as that may sound (perhaps to some). I'll take a picture of the Dyna 70 amp for you. It's also on those small monitors seen above. Those little speakers (sealed system) are not very efficient and really need some extra muscle, although I know their are schools of thought that wouldn't consider 35 watts/channel too terribly powerful. Erik

Hi, Phillip: I'm glad this was helpful. For fun I hooked up one of Will's ST70 modifications which, whith a very interesting ground scheme I discovered for it, is extremely quiet. As you know, a quiet background is always a good thing! I can take a picture or two of that if you like, as well. I have been aware for years of the many dynaco modifications available from different sources, and I was just interested in Will's interpretation and tank-like, powder coat build quality of the original circuit. I'm sure the MC-240 was a marvelous amp. I wanted to ask you about your Edgarhorns: Which were these? Do you happen to have a picture of them? I hope things are going well, Erik

VacuumTube 1954: I agree that these old organ amps are a very economical way to 'get into tubes.' To me the frequency response is balanced well, and there are no bias adjustments. Not to say that resetting bias voltage over time is necessarily a negative thing, just that the fact that the Baldwins are very much plug-and-play affairs, along with outstanding price/performance value. Tube rolling is obviously also very easily done. For those interested in a little DIYing or modification, the circuit again is really very simple. Minor changes in coupling cap value, for example, can have an influence on perceived frequency response and overall voicing. The sonic character of components is such a highly personal and subjective aspect of this hobby, and the big Baldwins are built in a way that gives the user a certain degree of input as far as input-output tube choice, rectifier type, etc. The "Winged C" 6L6s (from AES) do sound great, and I also recently purchased a pair of 5V4 rectifiers. You asked about the 12AX7, and I believe they are original Baldwin branded tubes. As mentioned before, this 6L6 amp worked great with Klipschorns. However, the Klipschorns can be pretty amazing on even a very, very low-calorie diet of less than a watt (in my opinion, in my room, with our music, and how we listen). I've been using them alternately with the Moth Audio 2A3 integrated amp I built several years ago (I purchased the parts and schematic from Moth) and an extremely good sounding little amp from Sophia Electric called the 'Baby.' Both the Moth and Baby have their own volume control, so along with a good source, the system is very simple to use and encourages listening over obsessive tweaking. Still, even with considerable headroom, the Baldwin is just fine for the big horns, and would be fantastic as part of an HT setup. If you haven't seen one before, here is the direct-coupled (no coupling caps in the signal path!!!) 2A3 Moth. Erik

"I have never even seen a discussion where anyone seriously considering the reverse. " I have done this many times with great success, and am doing it right now. I know of many who use a solid state preamp with a valve amplifier. CD players offer considerable gain, and in most cases are able to drive amps into the clipping range, making the use of ANY preamp (valve or SS) not really necessary. Preamps are actually used to attenuate strong source signals (like CDPs), and offer certain benefits like impedance buffering/matching between stages. I also use non-tube Lexicon processor in our Home Theater system, and it works extraordinarily well with the push-pull and single ended tube amps. I have also used many different tubed preamp designs, including the one shown below which I built several years ago and used a great deal. Same with the Foreplay preamp, of which I built probably half a dozen different versions -- AC filaments, DC filaments, tube rectified, SS rectfied, and so on. I still use it sometimes.

I've heard the amplifier and had one on my workbench several years ago -- I wonder if the one you have is that very amplifier? Kevin Kennedy, who is quite well-known in many DIY circles, didn't build the one I worked on, although it was his design. I remember it having, as you described above, very punchy and tight bass response. My memory may be failing me here, but I think I found the highs just a little crisp. The circuit was built into a simple, unpainted chassis, and as I remember did have a large power transformer. Congrats! Erik

System from the front:

A closer image of the amplifier:

Hi, Rick -- I'm doing well. I've been occupied with some of my own projects, as well as staying extremely busy with school. We'll be finished in a week, so things will quiet down a bit. I hope all is well with you. Here is a picture of the Baldwin I got from Will a couple of weeks ago. I've used it with great result on our Heresies, Klipschorns, and Lowthers, although the power has been most useful with the two-way monitors shown. I had started this project with a pair of ceramic enclosures I had built for some other drivers, but accidentally dropped one. Unfortunately, fired clay breaks easily, and I haven't been able to find this particular size in Houston. In any event, these new cabinets are from Parts Express. I made the front baffles out of solid oak, and routed the driver holes to counter sink the frames. The first crossover consisted of a published circuit for the Seas woofer, and I was really unsatisfied with the performance. It was a higher order design, with impedance equalization and filter to tame a small peak; and the overall result to me was a sound that was closed in and dull. Part of that had to do with the padding of the tweeter, which I ended up removing altogether. My wife is happy with the smaller, more-decor friendly size, but the system was greatly improved by the 10" sealed subwoofer (also Parts Express). Single-ended triode amps for these monitors were a total mismatch, though the Baldwin and Dynaco 70 work very comfortably. Erik

I'll post some pictures of the current Baldwin setup later. I've only had the amp for a couple of weeks, and was very happy to be able to get another one. I have a couple of other amplifiers that have been extraordinarily good matches with Klipsch (and non-klipsch) speakers. One of those was a Transcendent Sound T-16 I recently completely rebuilt for a friend. In terms of hearing differences between amps, there are so many variables involved, but the Transcendent OTLs have always been examples where differences were more obvious. They are also incredibly well-designed amplifiers, and simply do not need exotic/extremely expensive passive parts to sound good. expensive passives can't improve a circuit design that is already inherently compromised. Erik

Lance: I understand your thinking. Audio really seems to be one of those fields where one can speculate and ponder a huge variety of possible combinations that 'on paper' should make sense. I've found over the years that really good synergy between components is something that can sometimes be hard to predict, but is obvious when it happens. Component specifications and response measurements can be grossly misleading. In my own experience, paying attention to impedance relationships between stages: (source output to pre input -- pre output to amp input -- amp output to loudspeaker load, etc.) has been helpful. Those are among the more obvious elements one might consider, but those same relationships exist within individual components, themselves, and can in part be responsible for the strength of one design over another. In other words, the design of the circuit in question rather than only the amplification device used (e.g. transistor or vacuum tube) may be a significant part of the equation. As of right now, I'm using a small solid state preamplifier that was remarkably less expensive than some tube-based preamps I have bought, built, or borrowed, and it's performance has been, as far as the actual circuit, at least equal to and often better than any of them. There is a downside to it, however: the quality of the volume pot is really rather poor in terms of tracking between left and right channels at lower rotations. For the time being, I'm accepting that compromise and making necessary balance adjustments. Turned up higher, balance is fine. I often wonder what I would do if I suddenly 'arrived' at system perfection. The search would end.................and, very probably, also much of the fun. Erik

My usual hiccup post: Will's other work sometimes takes him away from home for a few days, but he is always very good about communication. Erik

Morning, Vacuum Tube 1954: A little on the tired side last night, it would have been more accurate to have mentioned that my 6V6 amps were not redone by Will. Years ago I had purchased and overhauled a single mono 6V6 integrated amplifier to use with a vintage Eico FM tuner (also monophonic). I liked the sound so much I looked around for a bit and found another matching amp for stereo use. I'd be glad to post a picture or two of them later, but I must say that I find the sound of the stereo Baldwin a little more robust (just bigger, more palpable, maybe). Sheltie Dave: I've wondered about those amps often, and am genuinely glad they are still doing well. Those things were amazingly good with the Klipschorns, and honestly had greater clarity and seemingly more power than our Moondogs. I had made some changes to Lessard's already very good though more classical shunt feed output (aka parallel feed), and I would say that the sound of the amp was improved by the Jensen capacitors that were installed. Oddly though, I fairly recently installed a pair of the very same capacitors in the 6BQ5 headphone amp I built, and the sound was so strident and bright it was uncomfortable. A slight increase in coupling cap value and change of brand (again 630 volt Solens) were an improvement. The Jensens in the parafeed amp were really nice, though. The 5687 driver is a very significant part of the sound of that amp -- in my opinion. I have some ideas for tube pre using that same tube. Just have exams left at school, and then it's done. Thanks for the thought on that! Erik

More than anything else, Will Vincent is a gentleman. He also happens to do some of the finest audio electronics and chassis work I have ever seen. Erik