Chrome Magnum

Gorgeous interpretation of a Maynard design! You do yourself and him Proud!!

Annnnnnnd We're off!!! Looks like a very cool build!! Thanks for the pre-view!

I approve and thanks! I did want to do the post but I'm very happy that you did it already. The internets confuses this old guy sometimes. I hardly know how to Kindle someone on my Apple-Pod! =D (seriously, though, thanks) Also, Maynard sends his best!

Thanks! The amp circuit is a Maynard original. It uses 6SJ7's and 6BG6's I built it into the chassis first and tested it, so that I'd know if any of my add-ons were causing any issues once they were installed and powered up. Maynard's design is hum-less and noiseless and fortunately, my enhancements did not add any noise either. He designed it to accommodate those gorgeous NOS Coke can caps that I so wanted to use. That made it necessary to marry them with equally impressive OT's for aesthetic's sake. The good news is that those OT's bring a lot of base to the show, which Maynard's design powers through with ease. So, at around $400.00 total, the (4) Hammond X-frmrs represent just under half of the parts cost for the whole build. No surprise there. The chassis is a Bud Box from Mouser and the hardest part of the construction was making the various holes and cut outs perfect. I measured 4 to 6 times before cutting once. The analog meters were literally the only ones available that looked good/right. They are from e-Bay (Chinese) and even though this really isn't typical in my experience (even though there is reason to believe it should be), two out of four of them had minor problems which I did not discover until they were installed. (sigh) I took them out and fixed both (luckily) and re-installed. There are a lot of little extras, too numerous to mention but to name a couple, there's the pin-point leds that I used for the volume and tone knob markers and the tiny little chassis holes that you can just make out between each tube pair are access holes for the feedback pots. The small black knobs beside each output tube USED to be for cathode resistance adjustment. But Maynard's opinion was that that was unnecessary and it added potential for drift and etc. I bowed to his experience and replaced them with fixed resisters. However, that left me with some nice mil-spec 100 Ohm, 3-watt pots installed that were not doing anything. I ended up using the one on the left for the analog meter back-light dimming and the one on the right for the marker led dimming. Yay, mindless, harmless tweaking! Of course the feature that makes the whole thing pop is the integrated waveform and performance display. I wish I could take credit for it but the truth is, those are widely available as complete functional modules. This one was around $100.00. The user has only to power them up and supply a properly scaled input to them. They come in many styles and configurations, so finding one for your application is not a problem. The same goes for the signal generator. I considered making one from a dedicated chip but I found what you see here for $40.00,,, FORTY DOLLARS! For that I got a great looking, perfectly sized, digitally synthesized, drop it in the hole and you're done, audio generator... No brainer. You'll notice there are no through holes or bolts or rivets, etc in the deck. This gives the top side of the chassis a very clean look. Maynard always cuts some very neat little vents for his power resisters to cool through but I could/would not consider that for this build. What I did was install a 12 volt muffin fan inside which circulates air over those resisters. It seems to do a fine job as they stay cool and the deck thermometers stay below 90 degrees. I'm guessing that spreading the heat around inside the aluminum chassis allows it a lot of surface area to wick off through. That's the ten thousand foot view. I hope it helps but please contact me with any more questions/comments you may have. Cheers, Stu

Thanks for noticing! =D And thanks to everyone else who left positive comments!!

Many of you know Maynard the "Tube Amp Designer" and fortunately, so do I. In one of our talks, I mentioned to him that I had some NOS Coke Can capacitors that I really wanted to incorporate into an amp build. I said I thought it was time to build not only an impressive sounding amp but an impressive looking amp as well. Anyway, be careful what you wish for when Maynard is listening because within the week, he had designed and sent me the print for this dual mono SEP amp with truly impressive specs. He knew my love for tweaking, so he included a special front-end tone control circuit as well as an adjustable feedback network in the output section. That was last Summer. I have never before committed this kind of time to a build but I figured it was about time to see how high I could set the bar for myself. I must admit that my respect for Maynard's design was the genesis for that. A half year later and the "Tech-Amp" was born! Not only is it littered with displays and diagnostics for assessing it's operational status and performance but it also has it's own built in audio signal generator. No more finding my sig-gen and hooking it up. With this amp, I just hit the "TEST" button and the input to the amp switches from the front panel jack to the generator's output for immediate use! I hope you agree that it is an impressive looking amp and as for the sound, like I say in the you-tube video; "This amp plus the Klipsch KF-28's, make sure that my neighbors are listening to good music too!" And yes Maynard, I CAN blow out a match with the bass ports! =D I've attached some still pics and here is a short but entertaining You-Tube of it in action: (Sorry for the "Shaky Cam" in some of the transitions.)

You are a national treasure Maynard! And so are your designs! Thanks for making them as well as yourself available for us to build them... =] Transistors and chips?! I don't need no steenking transistors and chips!

Mouser's great! So's Maynard... Flawless design and execution as usual Maynard! You're designing 'em faster than I can build 'em! (Not complaining) =]

I'd request that you guys speak English but you're writing it so,,,, the trouble is surely on my end... Carry on... I'll be in the back seat, listening to the grown-ups. =]

Pretty! The more filaments the better. Makes me wish those metal tubes,,, weren't =] Thanks for the pic...

Thanks for that Sloth. Yeah, I thought your comment hit the "bit-bucket" too. My explanation looked a little weird without your question.

Thanks Carlooch!!!

So yeah, the first thing I installed was the amp and ran it for a base line so that I'd be able to hear if any of the stuff I added had any effects on the noise. All that stuff behaved and did not add any noise. So it's all amp noise, but not really that bad either. Stu

Apologies for the multiple posts of this one article. I had a heckuva time getting this thing to load (been trying for a day) and this resulted as part of that. Stu

Apologies for the multiple posts of this one article. I had a heckuva time getting this thing to load (been trying for a day) and this resulted as part of that. Stu

Apologies for the multiple posts of this one article. I had a heckuva time getting this thing to load (been trying for a day) and this resulted as part of that. Stu

Firstly, thanks to all for your comments on my inaugural post of me and Maynard's Little Gem. If I missed answering some of you that's on me. Your comments are all appreciated. What is "THE 99%" ? Recently, while showing one of my tube amp builds to my sister, I noticed her eyes glazing over. WHAT!?, NOT INTERESTING?! (I asked) Yup, I found from talking to her that not only did she not know what she was looking at, she really wasn't interested in finding out either.... She's a great gal but,,, REALLY? =/ I then realized that she as well as hoards of disinterested others, make up about 99% of the population. That's a lot of potential converts but as Cartman said in Southpark "How do I reach these kids?!" Since the merits of tubes amps alone aren't enough to impact the 99%. I figured I'd make one that would compel them to take notice and maybe even ask a question or two about it. (Check and Mate!) Enter, the P.T. Barn-Amp. It's as much a spectacle as it is an amp, The 5 channel light show is from XKITZ and is the main feature but I put in some stuff for us 1%'rs too, such as: Through chassis forced air cooling. The chassis holes for the 11BM8's are over-sized and air is forced past them from below. This air flow also cools the interior of the case. Auto soft-start. Upon power up, the orange light illuminates to show the soft-start circuit has engaged.. 15 seconds later, the orange light goes out and the blue one goes on to indicate full heater voltage is being applied. DC power supply for the filaments. Speaks for itself... Overheat indicator Shouldn't ever need it but I had some holes to fill... See below. The chassis is from an old piece of medical test gear. As such, it came with a pretty sweet ac input module with all kinds of filtering and de-spiking, which I left in and put to good use. The amp circuit itself is the popular George Fathauer kit that uses (4) 11BM8's. While I wanted to use a Maynard design, I had a lot to put in the case that wasn't amp, so I chose this one for it's compact footprint. Happily, I also found it to be quite listenable with lots of volume. My only two notes are that there is a small bit of background hum that's not affected by the volume control; small enough, that I haven't even bothered to look for it yet and the bass rolls off sooner than you'd expect it to. The former may just be B+ ripple and the later is probably due to the modest OT's that come in the kit. A number of on-line chats seem to support that notion. No worries though because an equalizer and two Klipsch RB-61's make it sound tasty. As expected, the 0A3's put on a great show in subdued lighting and they even show up in daytime. What I didn't see coming is that even though the 0A3's are from the same batch, they can differ noticeably in the amount of light they put out. What you see in the You-Tube is the best matching I could do with the 0A3's I had on hand. I prefer to use the amp with the Coke bottle gas regulators because,,, COKE BOTTLE GAS REGULATORS!,,, but I am considering retrofitting some 40W Edison bulbs with octal plug bases for insertion directly into the 0A3 sockets. That should satisfy anyone's brightness needs. Lastly, you'll notice some empty real-estate to the right of the light show controls. That area was planned to host VU meters but I ended up needing that space for the light show cpu board, plus as the amp came together, meters seemed superfluous. I guarantee you don't even notice it when this thing gets cranking. Maybe a nice logo could go there. Maybe not... Anyway, that's it. Show it to some 99%'rs and let me know what they say... Next up: A pedigreed Maynard design with built in real time diagnostics, status and waveform monitoring. To be dubbed; The Tech Amp (a Winter project so it'll be a while.) Thanks for looking and have a great Fall y'all, Stu

Firstly, thanks to all for your comments on my inaugural post of me and Maynard's Little Gem. If I missed answering some of you that's on me. Your comments are all appreciated. What is "THE 99%" ? Recently, while showing one of my tube amp builds to my sister, I noticed her eyes glazing over. WHAT!?, NOT INTERESTING?! (I asked) Yup, I found from talking to her that not only did she not know what she was looking at, she really wasn't interested in finding out either.... She's a great gal but,,, REALLY? =/ I then realized that she as well as hoards of disinterested others, make up about 99% of the population. That's a lot of potential converts but as Cartman said in Southpark "How do I reach these kids?!" Since the merits of tubes amps alone aren't enough to impact the 99%. I figured I'd make one that would compel them to take notice and maybe even ask a question or two about it. (Check and Mate!) Enter, the P.T. Barn-Amp. It's as much a spectacle as it is an amp, The 5 channel light show is from XKITZ and is the main feature but I put in some stuff for us 1%'rs too, such as: Through chassis forced air cooling. The chassis holes for the 11BM8's are over-sized and air is forced past them from below. This air flow also cools the interior of the case. Auto soft-start. Upon power up, the orange light illuminates to show the soft-start circuit has engaged.. 15 seconds later, the orange light goes out and the blue one goes on to indicate full heater voltage is being applied. DC power supply for the filaments. Speaks for itself... Overheat indicator Shouldn't ever need it but I had some holes to fill... See below. The chassis is from an old piece of medical test gear. As such, it came with a pretty sweet ac input module with all kinds of filtering and de-spiking, which I left in and put to good use. The amp circuit itself is the popular George Fathauer kit that uses (4) 11BM8's. While I wanted to use a Maynard design, I had a lot to put in the case that wasn't amp, so I chose this one for it's compact footprint. Happily, I also found it to be quite listenable with lots of volume. My only two notes are that there is a small bit of background hum that's not affected by the volume control; small enough, that I haven't even bothered to look for it yet and the bass rolls off sooner than you'd expect it to. The former may just be B+ ripple and the later is probably due to the modest OT's that come in the kit. A number of on-line chats seem to support that notion. No worries though because an equalizer and two Klipsch RB-61's make it sound tasty. As expected, the 0A3's put on a great show in subdued lighting and they even show up in daytime. What I didn't see coming is that even though the 0A3's are from the same batch, they can differ noticeably in the amount of light they put out. What you see in the You-Tube is the best matching I could do with the 0A3's I had on hand. I prefer to use the amp with the Coke bottle gas regulators because,,, COKE BOTTLE GAS REGULATORS!,,, but I am considering retrofitting some 40W Edison bulbs with octal plug bases for insertion directly into the 0A3 sockets. That should satisfy anyone's brightness needs. Lastly, you'll notice some empty real-estate to the right of the light show controls. That area was planned to host VU meters but I ended up needing that space for the light show cpu board, plus as the amp came together, meters seemed superfluous. I guarantee you don't even notice it when this thing gets cranking. Maybe a nice logo could go there. Maybe not... Anyway, that's it. Show it to some 99%'rs and let me know what they say... Next up: A pedigreed Maynard design with built in real time diagnostics, status and waveform monitoring. To be dubbed; The Tech Amp (a Winter project so it'll be a while.) Thanks for looking and have a great Fall y'all, Stu

Firstly, thanks to all for your comments on my inaugural post of me and Maynard's Little Gem. If I missed answering some of you that's on me. Your comments are all appreciated. What is "THE 99%" ? Recently, while showing one of my tube amp builds to my sister, I noticed her eyes glazing over. WHAT!?, NOT INTERESTING?! (I asked) Yup, I found from talking to her that not only did she not know what she was looking at, she really wasn't interested in finding out either.... She's a great gal but,,, REALLY? =/ I then realized that she as well as hoards of disinterested others, make up about 99% of the population. That's a lot of potential converts but as Cartman said in Southpark "How do I reach these kids?!" Since the merits of tubes amps alone aren't enough to impact the 99%. I figured I'd make one that would compel them to take notice and maybe even ask a question or two about it. (Check and Mate!) Enter, the P.T. Barn-Amp. It's as much a spectacle as it is an amp, The 5 channel light show is from XKITZ and is the main feature but I put in some stuff for us 1%'rs too, such as: Through chassis forced air cooling. The chassis holes for the 11BM8's are over-sized and air is forced past them from below. This air flow also cools the interior of the case. Auto soft-start. Upon power up, the orange light illuminates to show the soft-start circuit has engaged.. 15 seconds later, the orange light goes out and the blue one goes on to indicate full heater voltage is being applied. DC power supply for the filaments. Speaks for itself... Overheat indicator Shouldn't ever need it but I had some holes to fill... See below. The chassis is from an old piece of medical test gear. As such, it came with a pretty sweet ac input module with all kinds of filtering and de-spiking, which I left in and put to good use. The amp circuit itself is the popular George Fathauer kit that uses (4) 11BM8's. While I wanted to use a Maynard design, I had a lot to put in the case that wasn't amp, so I chose this one for it's compact footprint. Happily, I also found it to be quite listenable with lots of volume. My only two notes are that there is a small bit of background hum that's not affected by the volume control; small enough, that I haven't even bothered to look for it yet and the bass rolls off sooner than you'd expect it to. The former may just be B+ ripple and the later is probably due to the modest OT's that come in the kit. A number of on-line chats seem to support that notion. No worries though because an equalizer and two Klipsch RB-61's make it sound tasty. As expected, the 0A3's put on a great show in subdued lighting and they even show up in daytime. What I didn't see coming is that even though the 0A3's are from the same batch, they can differ noticeably in the amount of light they put out. What you see in the You-Tube is the best matching I could do with the 0A3's I had on hand. I prefer to use the amp with the Coke bottle gas regulators because,,, COKE BOTTLE GAS REGULATORS!,,, but I am considering retrofitting some 40W Edison bulbs with octal plug bases for insertion directly into the 0A3 sockets. That should satisfy anyone's brightness needs. Lastly, you'll notice some empty real-estate to the right of the light show controls. That area was planned to host VU meters but I ended up needing that space for the light show cpu board, plus as the amp came together, meters seemed superfluous. I guarantee you don't even notice it when this thing gets cranking. Maybe a nice logo could go there. Maybe not... Anyway, that's it. Show it to some 99%'rs and let me know what they say... Next up: A pedigreed Maynard design with built in real time diagnostics, status and waveform monitoring. To be dubbed; The Tech Amp (a Winter project so it'll be a while.) Thanks for looking and have a great Fall y'all, Stu

Hey look! Three posts in a row! Sorry folks, still getting used to this interweb whozitz.

Clean and tight as always! BTW, how closely do you have to match tubes that are running in parallel? Assuming there are problems with running unmatched tubes in parallel. There's gotta be...... right?..... Huh?

Clean and tight as always! BTW, how closely do you need to match tubes that are running in parallel and what, if any is the downside if you don't?

Thanks! I see you have some impressive equipment like Jim. I don't know what you think of your Carver stuff but Bob Carver was my hero in the '80's. I ran two M-400's in mono configuration into Magnepan MG-1's. When I opened it up all the way, it dimmed my house lights in time to the music. yup. Stu

You sound like another guru I have yet to meet. It looks like you are very prolific as well. Thanks for the comment! Stu P.S. My avatar pic is the head of a six foot tall stainless steel robot I built. Note his "brain" is tubes! I mention it because you commented on my improvisation.

This is my inaugural post of what I hope will be a series of posts chronicling my tube amp builds as well as my new found appreciation of Klipsch... It started last year when I retired from my career in solid state and digital electronics and got back to my first love... tubes. I stripped out an old 40's intercom desk box (pictured) that had always been a favorite of my son and installed a hand built Morgan tube amp in it. I tweaked it for more gain and when it first (gently) hummed to life, I was instantly transported back to my childhood. You folks who are around 60 or so know that sound... Sigh I then found an engraver who made the all in one face plate for it (note that I disguised the input jack as the old "Press to Talk" lever) and I presented it to my son. He likes and uses it but he does not share my nostalgia for the soft hum it produces when idling. Kids! =\ Enter Maynard "The Tube Amp Designer". I met him on-line and if you don't know his body of work, make it a point to. His contributions to this forum are invaluable. He suggested that if I wanted a tube amp with clean sound, I should build a stereo tube amp of his design that he had dubbed the "Little Gem". I built it and just as he promised, it is NOISELESS. You can't tell that it is on until you provide a signal to its inputs. When you do, the music just leaps out of the previously silent speakers like a tiger springing from the underbrush! Naturally, I wanted the amp to look as good as it sounds but even so, I had a problem with paying $100+ for a ready- made, chassis/ box. You fellow builders know what I mean. Fueled by that frugality, I drew on my first amp, the (intercom conversion) which inspired me to find and re-purpose another ready made enclosure for the Little Gem. After 40 years in the electronics industry, I have plenty of pieces of disused equipment to pick from and as you can see below, an old '90's Ethernet hub filled the bill nicely. I stripped out all the original electronics except the AC input module which left it with some very nice built in power line filtering. Another bonus is that this chassis is aluminum, so no eddy currents. I then built the Little Gem into it. (Pictured) BTW, even if you don't have a basement full of old equipment, there's always e-Bay. I just saw the exact same model that I used for the "buy it now" price of $20.00! I then housed the whole thing in an early 40's Philco home entertainment cabinet and added a few bells and whistles to make it even more eye-catching. The old phono bay is where the Little Gem now resides and it now opens electrically with the touch of a button. Also I couldn't resist putting lit VU meters on the amp chassis as well as a modest light show in the old 8" speaker location. BTW, I re-purposed the old phono turntable. It now hangs above my desk with two ten watt led's hidden where the cartridge used to be. The knob that used to switch the needle from '78 to LP is now a brightness control for the led's. Also, it's a great way to show case old picture disks. I take some flak for re-purposing as opposed to restoring old pieces but as I see it, their are a lot of well restored pieces out there and they all have one thing in common: they are all just as BORING as the day they were new. Here is a 60 second long video of the Little Gem it in action (yes, ACTION!) Bear in mind, I posted it before the Klipsch RB-61's arrived, (Read on) Enter Maynard (again): By now, I was very aware that he is a BIG proponent of not only single ended tube amps but Klipsch as well. He gently nudged me towards the RB-61's and since he hadn't steered me wrong yet, I confidently ordered them. As I hoped, they worked out VERY well and I have nothing but praise for them. Even though the RB-61's provide a sonic-ally accurate room filling sound even with a low power amp, I am the sort who without fail, eventually ends up turning it to 11. As such, am always looking for more volume. So months later when I saw the +98dB sensitivity spec of the Klipsch KF-28's which is a full +3 dB more than the RB-61's, I ordered them, with Maynard's blessing of course but that was out of respect for him as I am now a full blown Klipsch believer. I met the UPS truck in the driveway and I think it was under 5 minutes before I had them unpacked and hooked to the Little Gem! I was immediately struck by the extra volume and bass they provided. I know they aren't top-of-the-line Klipsch but wow, they look and sound great with the Little Gem. In short, believe the reviews. They do indeed present " A Wall of Sound"... They are what I now use with the Little Gem exclusively. The RB-61's are still GREAT sounding and more technically advanced, (as I believe) but I have decided to pair them with my next, more powerful amp. =] I am calling that amp the "P.T. Barnamp" because of its built in showiness and gimmickry. It is well on it's way to completion at the time of this writing. I hope to show it in another month or so. Thanks for the chance to get to know you and you,,, me! Stu