ToolShedAmps

Howdy All, The "Pre-Amplifier Build Thread" is officially started! If you would like to participate in the ensuing discussion, please head on over. Cheers! Matt.

Hi Krispy Kirk, The binding posts I use are actually REAL plated Copper, as much as I'd like to use the WBT Chinese "Knock-offs" to visually make everyone feel better, I believe they use a plated STEEL core. As for the "real-deal", I doubt very much you would be willing to pay the difference. Please see the link below. http://www.partsconnexion.com/WBT-74485.html Cheers! Matt. BTW, the binding posts I use cost $26.00 ea. Any customer can upgrade anything they would like and only be charged the difference at "cost".

Ok then, here we are. For those of you that haven't been following along I have been asked, nay, invited to build Matt Renaud's "Open Source" 4S Universal Preamp for the benefit of all forum members (both DIY'ers as well as Klipsch owners wanting to "dip their toes in the water (with Tubes)" and simply purchase one of mine.) I have agreed to create this "build thread" with the express purpose of informing through pictures and text, MY process of constructing a "variant" of this pre-amplifier. DIY'ers are more than welcome to build their own and leverage this thread for help from myself as well as other knowledgeable forum members to achieve a successful outcome. I will detail my thought process (as best as possible) to provide some insight into the whys and hows of the variant I will be building. DIY'ers are welcome to build the project "as written" (the link to the original project published on DIYAUDIOPROJECTS is listed below) OR, they can "feel free" to build my variation (in fact, I hope they do, I can always use more POSITIVE feedback). Without further ado, lets take a look at the original project...... http://diyaudioprojects.com/Tubes/Universal-Tube-Preamplifier/ After you have familiarized yourself with the circuit and design elements, we will look at what I propose to build instead... Stay tuned.... Matt.

Honestly, I believe it to be a function of operating point. Rarely is it a specific tubes fault. Almost EVERY tube has a linear region on it's data sheet that allows for low distortion. Some tubes respond better to loading and type of bias than other tubes as well. It more or less becomes a function of what the "chef" is doing with the ingredients than the ingredients themselves. BTW, I know this sounds vague, but, in reality there is no better way to explain it. Short story; awhile back I had the opportunity to pick up a pair of WE 437a's for not terribly that much money. So I proceeded to design a single-gain stage with it (bread-board). I think EVERYONE would agree that this tube is exceedingly linear with as close to zero distortion based on it's curves and plot. Well, it was NON-MUSICAL. Sterile, Dry, let me be perfectly clear, I tried everything I could think of trying to get it to sound good, inductive loading, inductive-parafeed, 9v battery, LED's, you name it. BLAH. My point is, without a "little" 2nd order distortion, it may as well be a transistor..... Cheers! Matt.

This is the pre-amp I was asked to build, and, many who have built it, like it. Like I said before, I am going to "do my thing" with it and I suspect my changes will make it better.

Later on this evening when I've "hit the wall" from woodworking and milling Aluminum I will start the new build-thread in the Talkin' Tubes section. Matt.

BOM? Bill-Of-Materials,

Good Morning William Good Morning William, I intend to list the suggested "Changes" to the original circuit for the DIY'ers. I agree with you 100%, as the "noval" small-signal "triodes" go, the 12AU7 is a fantastic sounding tube. The additional gain provided by a 12AX7 in this design is going to remain "un-used" anyway, so, we might as well tailor the circuit to optimize the lower gain 12AU7. Matt.

Good Morning Carl, Heavens no! I will adjust the BOM to include at least a Mini-DPDT toggle and Two Pairs of inputs for the DIY'ers who intend to build the Pre on their own. Both versions of my Line-Stage will have FOUR pair of inputs on a rotary switch. Matt.

Good Morning All, I've got to get some work done today, however, I did want to post the open source Line-Stage design that we will use as the basis for the new build thread. http://diyaudioprojects.com/Tubes/Universal-Tube-Preamplifier/ Giving credit where credit is due, we would like to thank Matt Renaud for this great design. All of you DIY'ers out there should be able to get yourself into this pre-amp for as little as $500 as designed. I'm not one to leave "well enough alone" so, I will be building two variants that will be offered for sale both on my website (at a higher price to non-Klipsch Forum members) and directly to forum members via private messaging. The target pricing for these variants will be: $800.00 for the "standard" version ($999 on website), and $1500.00 for the "Reference/Custom" version ($1999 on website). I will provide a breakdown of the differences between the two versions in the build-thread. So without further ado, take a look at the linked design and get ready to rumble... Cheers! Matt.

So how did the "ToolShed" measure up ??? - Matt is building me a custom G6 now, paid for sight unseen... After a nice long session with my SS yesterday, those tubes have some serious competition!!! This inquiring mind is chomping at the bit My guess would be that you won't be disappointed. where are you located at? you can't be too far if you went to an amp meet in st. louis. A 'Burb of Milwaukee, Wisconsin. It WAS a nice drive, there and back in the same day.

So how did the "ToolShed" measure up ??? - Matt is building me a custom G6 now, paid for sight unseen... After a nice long session with my SS yesterday, those tubes have some serious competition!!! This inquiring mind is chomping at the bit My guess would be that you won't be disappointed.

Good Morning All, I just wanted to give a "Shout Out" to Sheltie Dave who was the most gracious of hosts, and the guys at the St. Louis event. These guys could not have been more welcoming and open-minded. I had a fantastic time and I hope to be invited back to the next event. Additionally, I also wanted to give a special thank you to "Mark" and his VERY SPECIAL 6B4G Push-Pull Amplifier. For those of you who think that ONLY DHT SET's can sound great, Mark, Myself, and Marks AMP beg to differ. Bravo! I'll look forward to hearing it again. Again, Thank You Gents so much! Cheers! Matt.

Howdy All, Some wonderful news this morning. I have been asked (Invited) to build someone else's Pre-Amplifier design for the purpose of getting a great-sounding, entry level, TUBE Line-Stage into the hands of Forum Members who would (if so inclined) have to otherwise source one from China. The beauty of the design is that it is "open source" and widely available to all. So, if you are a DIYer and would like to build your own, you are more than welcome to do so. We will start another thread in this section to use as a "build example/forum help" thread. This Pre-Amplifier will mate well with many Solid State amplifiers that forum members currently own. So either build your own, or, purchase one of mine. I am taking the liberty of deviating from the published "open source" schematics to better suit my style. These deviations will be extensively documented on the thread so that potential buyers and DIYers alike have equal understanding of the choices I am making during the construction phases. This Line Stage is a simple grounded cathode design with enough flexibility to have fun with it. It will have two switchable inputs, a single pair of outputs, and a stereo volume control. This is an ALL TUBE design using a tube rectifier and a single triode output tube section per channel. More details to follow. Cheers! Matt.

I beg to differ, do you drink Coke? Do you use an iPhone? Do you really think the owner of your favorite Bar-B-Que joint is going to tell you what is EXACTLY in his rub? I've had it with you. I am no longer going to respond to your attacks. FYI, my customers LOVE their amplifiers....period.

Which one is it? It just seems odd you changed your operating point after Maynard pointed out it exceeds the tubes max ratings. And of course by some magical device "bypassing" a zener. In every picture you have posted there is nothing bypassing the zener. I circled the diodes in green, there is an orange wire going to pin 4 on the octal sockets and nothing else. I also see you don't use any insulation on component leads that have high voltage present, and to make things worse they are in close proximity to one another, hopefully nothing touches. You, guy, are specifically the individual intent on attacking me. What have I done to warrant your disdain? I will give you one last chance to be civil. Please read the 1st sentence of post #68. BTW, the turrets that I use have a hole that goes all the way through the turret. You cannot "see" the underside of the two items you have circled in green. So, if you REALLY want to dissect my work, buy one of my amplifiers. Better yet, will I see you at the event in St. Louis tomorrow? If so, then you can actually HEAR one of my amplifiers. Matt. Oops, almost forgot, I am very sorry for the quality of the photo you are using to point out my deficiencies, all of the leads on every single item is passed through CLEAR TEFLON TUBING. Although I'd prefer to use "air" or Chinese Silk, or virgin Egyptian cotton as a dielectric, none of them is as SAFE. Matt.

Which one is it? It just seems odd you changed your operating point after Maynard pointed out it exceeds the tubes max ratings. And of course by some magical device "bypassing" a zener. In every picture you have posted there is nothing bypassing the zener. I circled the diodes in green, there is an orange wire going to pin 4 on the octal sockets and nothing else. I also see you don't use any insulation on component leads that have high voltage present, and to make things worse they are in close proximity to one another, hopefully nothing touches. You, guy, are specifically the individual intent on attacking me. What have I done to warrant your disdain? I will give you one last chance to be civil. Please read the 1st sentence of post #68. BTW, the turrets that I use have a hole that goes all the way through the turret. You cannot "see" the underside of the two items you have circled in green. So, if you REALLY want to dissect my work, buy one of my amplifiers. Better yet, will I see you at the event in St. Louis tomorrow? If so, then you can actually HEAR one of my amplifiers. Matt.

Hi Jim, I'm glad that you have asked the question. Don't worry, I won't be "Chased Off" that easily. To answer your question, I pretty much "gave away the goose" at the end of post #68. You are "right" (and so is Maynard) when you stated that pretty much everything has been done before. The topology is a fairly standard grounded cathode amplifier, the differences are minor, but, important. As in all things (such as "Pitching"), the difference between a dirt-ball and "painting the corners", at the mound, may only be a fraction of an inch on the release. So, I'll say it again, I reserve the actual operating points for myself and my customers. I understand that someone may want to buy one of my amps and then proceed to "reverse-engineer" what I've built. That's fine, unfortunately, going forward I guess I will have to "deface" all of the resistors, capacitors, etc., in an effort to protect my time investment and prevent someone from just looking at a "gut-shot" and duplicating my work. BTW, the "lifetime warranty" is void the moment someone "drills-out" the safety screw every one of my bottom-plates is attached with. OK, the power question regarding Matt's amp. His amp yields nearly 6 watts running a pair of 6L6GC's, while, running a pair of my "fav's" the 6W6GT, the power output will be a hair over 3 watts. I'm NOT running grid #2 at red-line because I'm dropping B+ through a 100v Zener bypassed with something which is only allowing 173v to reach that grid. G3 is tied to ground rather than the cathode or (God forbid) the plate. I'm using CCS biasing at 40mA. The OT is a 5.7K to 8 Ohm unit with a DCR which I will NOT specify. The Pentode drivers (EF86's) are wired as pentodes, NOT strapped, I LOVE this as a driver, it can swing nearly 60v P-P and doesn't require a follower to lower the impedance. Well, truth be told, I actually prefer the E80F I hope I've answered your question? Thanks, Matt.

Howdy All, I forgot to mention who I draw inspiration from; Thomas Mayer is probably my favorite living circuit designer. He has the technical "know-how" and "balls" (can I say that on a forum?) to think outside of the box...I love that. Secondly, I really admire Steve Deckert, the guys at Zu Audio, Mike Morrow, Zach at ZMF headphones, Mike Moffat (whom I know from when I sold Theta) from Schiit Audio, for providing me a sound business model to follow. Dennis Had, for his truly excellent CAD-300SEI that has pushed me to build something I could be proud of. There are others, you know who you are. But, at the end of the day, I build EVERY SINGLE AMPLIFIER, myself... God Bless, Matt.

Hi Maynard, Thank you so much for the clarification. I felt that being misleading early on was the best way to preserve my true operating points. For that I apologize. I am not Nelson Pass, nor Lew Johnson, nor Dennis Had. I have however, sold ALL of their designs (to some degree or another). If you haven't been to my website then you don't know my background. I am an "Industry Insider", having sold the bulk of the "High-End" for more than 25 years (I turn 50 in a couple of weeks). So, I know these guys personally, along with several others; Eve Anna, Dan D'Agostino, Paul Hales, David Wilson, etc... Anyway, my business partner passed away from cancer a few years ago. Having a distinct "bad taste in my mouth" regarding the condescending nature of the "High-End", and knowing the "truth" relative to low-powered single-ended amps driving efficient speaker loads. Coupled with my wife having gained a full-time position as a teacher in a public school system (health care ) I decided to "pull the trigger" on my lifetime dream (built my 1st "Knight" amp kit when I was 12, amongst many others was Nelsons Aleph 1). So here we are. To answer your question more specifically, I'm actually dropping B+ through a 5 watt 100v zener to G2, the "trick" is figuring out what I'm bypassing it with. Matt.

Well OK then, I have just sat down in my comfy chair, keyboard in hand. Let me be the 1st to apologize to all those affected by this negativity. I'M SORRY. Moving on, I really do appreciate the desire to learn more about what makes my amplifiers "tick", however, my initial post should have stated, "I'd be happy to answer any questions you have aside from specifics relative to operating points (trade secret)". On the other hand, I am more than happy to discuss power supply ideas, biasing topologies, the continuing debate relative to lower gain/higher transconductance vs. higher gain/lower transconductance, woodworking? Etching non-ferrous metals? Pretty much anything else.......as I think that the "Empirical" data that I have gleaned from all of the sleepless nights and time spent away from my family is worth keeping "close to the vest". I'd like to tell a short story, very short. My wife is an educator in a Middle-School. The children she teaches have a saying that up until now, I really didn't know what it meant. After all, me, being a socially awkward introverted slob really didn't have cause (nor opportunity) to be impacted by its meaning. So this morning I attached a link to this very forum (like a proud papa) and what was the response? Same as the saying that the middle-schoolers like to use: haters gonna hate. Now far be it from me to teach Civility101, but, nary a "good job" from any of you. Just sayin'. Now that I've gotten that off my chest. I would like to be abundantly clear about several things, conjecture is nice, but asking is better. Lets start with what/who has influenced my designs. Better yet, lets start with, the fact that the "INVENTOR" of the grounded-cathode amplifier is LONG DEAD. Everyone's topology is derivative to some degree. I think we can all agree on that. Beyond that there are ideas that either work or don't work well at all. Now I can lay out a load-line about as well as the next guy, get my kid to help me with a bit of the more difficult math, stick the parts in a box and wire it up. It may work, sure. But does it make music? That is an answer alluded to by another poster on this thread, it is entirely subjective, impacted by numerous variables. I think my amplifiers make music....driving Heritage Klipsch speakers at listening levels that are not going to create substantial hearing loss. I really enjoy the music, and my goal (I'll never get "rich" doing this) is to simply help others "hear what I'm hearing" for not a lot of money. Is that bad? Thanks, Matt.

Whoa....apparently this forum is for armchair physicists and DIY-ers to share ideas. I build a product/s that sound awesome, look good, AND pair exceptionally well with PWK's designs. The point is, I'm not about to discuss in detail how I manage to build an amplifier that sounds better than those available (according to the latest review) from Dennis Had, and Nelson Pass. Simply put, I listen with my ears, not my eyes. Data Sheets are all well and good, however, in most cases they provide "suggested" operating points, which were created in a time before Teflon dielectrics, amorphous-core OT's, noiseless 1% metal-film resistors, copper foil & oil coupling caps, SAND, 24/192, etc. The most important point is: By constantly insisting and suggesting their are "better" topologies, tubes, methodologies, etc., and THEN demanding raw data to support these positions, just simply serves to SHRINK the possible "pool" of enthusiasts who would otherwise enjoy what a tube amplifier can do for their enjoyment OF THE MUSIC. Nuff' said

Howdy, Howdy, Without going into to much detail, the MAX output of the Genesis6 using 6L6GC or KT-66's is 5.86 watts. Using the 6W6GT (my particular favorite for this operating point) yields a hair over 3.2 watts with 200v on the screen. MORE importantly, the "proof is in the pudding" so they say. As far as "not understanding" why builders allow for "tube rolling," one glance at a data sheet will show you that load impedance is not entirely a "fixed" parameter under EVERY operating condition. Most valves will function regardless of operating point provided one or more of the MAX conditions are not exceeded (or nearly exceeded for more than one parameter). Therefore, before making snap judgments based on data alone, what is necessary is "playing" with operating points to find the "sweet-spot" for a particular topology. I am NOT inclined to comment on other builders' topology, methodology, parts quality, aesthetic appeal, etc., I know what works for me, and I believe that one listen would confirm what many customers (such as my last post supports) enjoy about my particular flavor. Matt.

A recent customer posted a short review of one of my amplifiers that I thought I would share. http://www.audioaficionado.org/pre-amps-amplifiers/33566-toolshed-audio.html

Hi Mike, that is a very nice amp! Beautiful layout! I am a huge fan of PRP resistors, I use them on the Cathodes of my amps exclusively. Nice work!