henry4841

I mentioned Roger Modjeski at least once on this thread. For those that do not know who he is he taught electronics at one of the Ivey League schools before starting is own company. Unfortunately for us tube lovers he passed away in Dec 2019. Two of his presentations are on youtube at the BAF conference. Below is a link for those interested in his accomplishments. https://www.ramtubes.com/about

I knew an old man once when I was young who said him and his wife of 50 years had never had a fight. But he went on to say "yes they have been known to wake up the neighbors discussing things on a few occasions."

Thanks for posting pictures. Nice to have another tube electronic geek ,tech, on this forum. I've built a couple of those Chinese kits and was well pleased with the sound for what they cost. What surprised me most on those kits was the iron, not bad at all.

Toe tapping is a good indicator you like what you hear. Best if you do not realize you are doing it.

I am in your camp myself now. Quit chasing my tail like a dog who will never catch it.

You need a DC voltmeter to determine that.

Use a piece of wire and solder it to the connections. Common problem, easy to fix.

The song "Nothing Compares 2 U" was one of my favorites way back then. Strange woman though in appearance and actions. RIP

I just want to add about the comparison of this amp and tubefanatic's (Maynard) Little Sweetie. As the suggest the Sweetie's sound is sweet. The Sweetie uses a tube the 6Y6 tube which predates the 6V6 tube and from the research I have done on the web was introduced around 1937. If you want to hear the sound I am sure some of our ancestors heard way back then well the Sweetie is the one to build to hear that sound.

Pictures of amps would be appreciated in the tube section under the title "Pictures of your Tube amps."

Those that have been keeping up with this build may notice an improvement in distortion in this build vs the original one I also checked before taking apart on page one. No parts were change other than new resistors and better layout and technics learned from years of diy. Much cleaner signal. Notice a 60db difference between primary signal and PS noise. I may have misspoken and said 50db is quite on another thread, subject, but 60db is what I know to be quite enough on my 103db LaScala's. If I put my hear inside my bass cabinet I do hear a tiny amount of hiss but nothing a ft. or two away.

Different but same sound. Contradictory statement but both are SET's with the Little Sweetie being more lush I guess is a good word. Little Sweetie has more personality that many would like. I do at least. That 6Y6 tube in the Sweetie has personality. This 6P15P amp is more what one is used to hearing from a SET amp.

I would like to comment on the accessary mods which are extra on the Decware Zen. Steve adds some small value film caps across some of the electrolytic capacitors. This is a common addition for many designers thinking adding a .1uf across a large electrolytic cap is going to improve the sound. It could very well change the texture of the sound to some degree. Some may well call it an improvement. They are very inexpensive except for the time it takes adding them in the circuit. Personally I thing it a waste of time adding a small value film cap across an electrolytic. I've seen designs where the main electrolytic cap can be 1Kuf and designers add a .1uf film cap. Just how can 1/10 of a uf can improve the sound of a 1,000uf one no matter the type. The thing most do not consider is there is nothing sonically wrong with the sound of an electrolytic capacitor. Nelson Pass of Passlabs recently used a large 10Kuf cap on the output of one of his projects. This was common in the early seventies in amplifiers and receivers, a large cap between the amplifier and the speakers blocking the DC. I first heard of an electronic sounding fine from Roger Modjeski in one of his lectures at the Burning Amp Festival in San Francisco. He even went on to say if it were not for the slight amount of leakage all electrolytics have he would use one for a coupling cap, in the signal path in a tube amplifier. He went on to say call me a heretic for saying this. Just use a good Nichicon cap and forgo all the trouble installing film caps across an already great sounding electrolytic cap. There are electrolytic caps called audio grade for those wanting the best which I will assume are better made ones. If one wants to build a SET EL84 such as this on a budget I say use an electrolytic in place of the 3.3uf film caps on the input tube. I do not believe it will hurt the sound in the least. In fact one could use a larger value electrolytic cap which may improve the sound a touch over the small 3.3uf film cap.

Steve adds two switches on the Zen he sells. One for changing the resistance of the cathode on the input tube changing the texture of the sound and another for two source inputs. This amp is for my personal use and I have no need for either. I consider the switch on the input tube as a gimmick, some may like it though, but the other most will appreciate having the option of two inputs to switch between. I do that with my B1 buffer not needing two inputs.

Do not expect an answer because I am almost sure the original poster has moved on. At least I have not seen him in months. As far as CBH, well let's just say he is no longer here either. I miss Curious George but I am sure he has his reason for not participating lately. Very knowledgeable guy.

When you are only using a few milliwatts of power even with a 2 watt amplifier you have plenty of headroom for transients. Anyway oscilloscopes show transients and Nelson has proved in his lab multiple times to non believers using his conventional speakers that the signal stays in the one watt window and it is loud in a big listening room. The fact is in this discussion of needing tons of power with our speakers is plain BS by those selling those big amplifiers. Auditoriums were filled with sound with horns and 5 watt tube amplifiers for decades before SS was even heard of. With the transients others on this forum always bring up. I do not care to convince anyone knowing the truth myself but it is annoying hearing this over and over. All this said if someone wants to shell out money for high power amps I say go for it. If the first watt sounds great all is good but you will be wasting money on watts that will never be used. One of the best amps on my speakers I have heard was with a 1 watt amplifier.

That is the volume pot. This amp has enough gain not needing a pre. You could always turn the pot wide open and use a pre though. In fact that is the way my system is but not an active pre but rather a Firstwatt B1 buffer. I probably have a better looking knob but at the time I just put on what was handy. This amp will not get much use, not that it does not sound good but because have other SET's I like better. It is nice though when this amp becomes a topic on the forum I can pull it out and hear the sound it makes again.

I just realized that I have not shown some better pictures of the finished amp. Probably look better if I painted the awful blue PS transformer black but I was too lazy to take the time to do so. Can always be done in the future if I decide to.

Scott working on old equipment myself, but only as a hobby, I have found when the capacitance increases it is a sign of the cap being tired but can still check within tolerance. I would replace them myself even if they have some limited time left. And I am not a fan of replacing caps in a crossover network just because one can. I would not give the magnetism thing another thought if they are not alnico magnets.

Guys with those high powered amps, our speakers only need a couple of watts. Most listeners never exceed the 1watt window. Easy to check with VOM if you disagree. If you perceive a better sound with an amplifier with more watts it is not the quantity of watts but the quality of the first few watts that is making the difference in sound. Those with an electronic lab can verify wattage used with a scope easily. Nelson Pass of Passlabs and Firstwatt has proven this in his lab with an oscilloscope set for a 1 watt window for years with less efficient speakers than our horns. The hype spread by manufacturers of more is better is just that, a fallacy to promote their products. Now if you have some of those old Bose 901's you will notice a difference in sound going from a 100 watt amplifier to a 200 watt one. I know this from experience and not theory but with speakers that exceed 100db with a watt, gobs of power is just wasted. With our speakers we are able to use those quality built SET tube amplifiers other speakers cannot reach their full potential with along with the better sounding low wattage class A SS amps. To put it another way, how is 100 watts or more over what what you are actually using going to make the sound better? Just last week I measured an average use with my LaScala's at what most would call loud music with less than 1/3 watt. Never exceeding 1 watt on peaks.

I want to say after rebuilding this amp and more closely looking at the schematics Steve Deckert has published I like what I see. Steve has overbuilt this amp to the extreme if he is still building as per the previously published schematics with the parts list. For instance the EL84 cathode resistor. It is shown as a 5 watt one where a 2 watt one would be overbuilding being the resistor is only dissipating .66 watts on my amp. Another example is the choice of 450V power supply capacitors where a 400V or possibly 350V one would work satisfactory. If built like the schematic I can see how he can give a lifetime warranty. At a price of $1200 and hand built with quality parts I can honestly say it is a good deal for someone wanting a quality built amplifier you can pass on to your kids when the time comes. For diy'ers it is a easy relatively easy amp to build and if on a budget can use good satisfactory parts and still get amazing SET sound. I highly recommend this amp even with the long waiting period.

I was thinking the 510 was a horn from another vendor and not a Klipsch horn. Is the 510 a 1" horn? A 1" driver that will go from 500hz to say 18kz is few and very expensive to be able to make a two way speaker.

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Being 74 he was somewhat before my time but since getting old and listening to some of his music the last few years one has to admit the guy could really sing. His recordings with Lady Gaga are some of my favorites and I am not a big fan of Gaga. Her music is just not my taste but like Tony Gaga has a great trained voice. RIP

To make it simple, if you see 1.62V average with your digital voltmeter you have reached 1/3watt assuming you have 8 ohm speakers. As stated in most all speaker spec's it takes 2.83V's into 8 ohms for 1 watt. When listening with my new amp checking usage the other night I never saw a full 1V of use. In the neighborhood average as loud as I normally use I saw an average of less than .5V usage. Most are shocked just how little power our speakers actually need. While checking this amp I noticed Steve is just running around 2ma of current through the input tube 6P1, not much. Looking back at Maynards Little Sweetie I saw much the same from his input tube. I reached out to Maynard and confirmed just a few milliamps is all that is needed for this tube as well as his build. Learn something everyday playing with electronics trying to learn more about circuits.