henry4841

When younger I put a lot of emphasis on numbers. Not any more. Designers, I am talking renown designers who are respected in their field, design a component with the emphasis on what they consider as best sounding hoping there are enough buyers that agree and buy their product. On higher end components, none would be considered bad, it comes down to the sound you prefer. Being a Nelson Pass follower I remember him saying, "For decades I designed amplifiers with great numbers, now I build amplifiers that sound good to me" not forgetting decent numbers with most times some 2nd harmonics and a touch of 3rd thrown in. I have not heard Nelson's higher end products but from his sales many must agree with his statement. It is funny to me that his main market is not the USA. Waiting list for many of products says a lot. Selling them as fast as they can make them. I try and respect everyone's opinion on this forum. Very knowledgeable and devoted followers of Klipsch. At least most of them.

There are million dollar amplifiers out there, at least Nelson Pass says so. Do they sound that much better than a $5k amplifier? I will never know. 🙂 But why worry about such, if someone has the money and wants a touch, %, of what they consider better good for them. Heresy's sound mighty fine from what I hear but it appears the Jubilee is selling well for those that can afford them.

Yes I do, many of both in fact but I do most listening with SET tube amps. Why, simple answer is I can. I've not found a big difference in sound with higher end SS vs tube PP amps. With SE SS vs SET tube amps I favor a really well made SET tube amp over transistors. As many on an audio technical forum say, tubes still rule when it comes to sound. Reason for tube vs SS PP amp? Price, you can buy a PP tube amp for less money than a SS PP amp, but I am talking serious audiophiles searching for best bang for buck. Honestly some of the cheaper amps, run of the mill consumer offerings, sound really good these days if one is not too picky. Much like a little car will get you where you want to go much cheaper than a Mercedes.

You may want to check your home town for an audio shop. There is one, Classic Audio, that has a tube tester one can use for free in my local.

I would not put to much faith with sellers offering matched tubes. All depends on how they are matched and if you ask the inevitable will say yes on whatever you ask. Roger Modjeski on one of his presentations at BAF commented on this.

Not sure if you have electronic skills but a far better way to match tubes is to measure dissipation of the tubes using ohms law in your amp. Old tube testers are very suspect unless refurbed by qualified tech. I can explain how if anyone interested.

Tube depot has 3 pairs at different prices. From 3K to 10K for NOS. I have seen others on the net claim you have never heard a SET 300B until you hear it with NOS Western Electric tubes. Personally I doubt I would hear that much difference myself but since we cannot say what someone else hears that I do not does not mean it is not true. I will never know at the prices those things are bringing now. https://www.tubedepot.com/products It appears the link does not work so one must got to their site and search for 300B. https://www.tubedepot.com/

And at your house, room.

SS PP amps definitely produces better bass at the expense of the best mids, vocals, sound stage.

My experience as well comparing SET300B to SET EL34 family of tubes. Bigger sound, better bass and holographic imaging with bigger tube especially at low volume. The thing is a SET has the best mids one can ever hear that puts the singer in the room with you as well as the instruments. As PWK was often quoted as saying, "music lives in the mids" and there is no better mids than horns and a good SET. A decent sub fills in the bass where a SET compromises somewhat in the sound. Not to say a good SET does not make decent bass it is that many have over emphasized bass reproduction in music desiring more bass than actually necessary. I most often never turn on my sub with an SET and LaScala's myself but many are bass crazy and that is what subs are made for. A SET is definitely for someone looking for the best in sound and the mids are the first place to start.

When you find a tech just replace those old power supply capacitors instead of trying to bring them back to life. Labor is going to be the big cost and not the parts. As far as Bottlehead gear, probably best to bring up on a variac but my guess no problem just plugging them in. But it is your gear.

Kinda expensive comparing SET 300B amps. I have not priced a well made 300B's in a few years but back then they were around $2,500 and since inflation I would expect the price to increase. From my limited understanding the output transformers play a big part in getting quality sound from a SET and especially a 300B. My only experience is with well reviewed Edcors, Hammond and Electron One iron which are middle of the road when it comes to OPT's. The technical side of me thinks OPT's are no more than wire wrapped around an iron core but many put a lot of emphasis on them. I am sure cost cuts were made in the iron on the Willseton but on the two Chinese kit amps iron I have built they looked and sound really good to my old ears even if made in China. Positively not name brand iron but decent for what the kits cost which I am sure applies to the Willsenton as well. The Willsenton wound probably benefit from some Nichicon capacitors throughout as well as some modifications on the design but who knows where the design came from. A SET is so simple in circuits it should not be a problem for a decent technician to understand the schematic it is built from.

And I bought both being young and trusting specifications. Both pieces DC300A and IC 150 pre were highly reviewed and praised for their great spec numbers. None better with either piece. Better specs than the test equipment the labs used. Now I mostly just use SET tube amplifiers with the worse specs of all the classes of amplification. Got caught up in the hype of all the rags that praised gear according to numbers at that time in audio history

Like CCG I believe every serious music lover should have both, a really good SET and a really good PP amplifier whether one prefers tubes or SS. Single ended amps in SS are few but out there. The biggest difference in sound I notice is between the sound of an SET and a PP amplifier. As far as a SET 300B, there is a reason some pay $25K for a Japanese SET 300B and it is not because they like throwing away money. I presently have over 20 working amplifiers and my SET 300B is my favorite. I can still enjoy others, none I have kept sound bad, and all sound excellent in their own way or I would not keep them. Having built an EL84 from Decware's schematic it is a very good introduction to the SET sound but way overhyped by a colorful guy on Youtube. There are better sounding SET's out there including Decware's other offerings I'm sure. No doubt Steve Deckert builds and sells a quality product and should be considered when purchasing a new amplifier. Hats of to him. And for the money the Zen is a good introduction to tube sound and could well satisfy many and be their last amplifier purchase. Then there are us that or always looking for the extra % of excellence in sound. And that cost money. Also I bet I could improve the sound of the Willenston for not much money if the iron is somewhat decent. There has to be cost cut considerations for a 4 tube 300B SET at that price even coming from China.

Another thought, not fair comparing a Chinese SET 300b against the Zen. I am sure if you compared Decware's SET 300b against the Zen you would hear a remarkable better sound from Decware's 300b. Output transformers make a lot of difference in the sound of a SET. Steve has stated he uses Edcor iron which are excellent OPT's and there is no telling where the OPT's are made in the Wellsenton. Decent I am sure but probably not the best for those tubes.

Here is one of the schematics published on the Zen. https://www.decware.com/newsite/ZKIT1.pdf Very few parts and I can see nothing spectacular about the circuit. As stated previously it is almost impossible to improve on SET amplifiers that the old timers got right decades ago. The data sheets of tubes are very thorough and one can depend on the guys knowing what they were doing and the figures are accurate.

Nothing special in the published schematics I have seen. In fact Deckert took a few what I would call shortcuts, just one cathode resistor for both channels. There is a recent thread here with the schematic. Does not matter because your ears are the only thing that matters and if you favor the Zen over others that is all that matters. Enjoy both of your recent purchases. In my world my SET 300B with just two 300b tubes is the one of many I own and is the last amplifier I would want to part with. My experience, all things being equal the bigger the tube the better the sound and sound stage. There is no way of telling the iron you have in your Chinese amplifier but from my experience with Chinese tubes the iron is really decent.

Interesting being having an EL84 amp, which is very good sounding, I was not that impressed. Great sounding, do not get me wrong, it is a SET tube amp but I have many tube amplifiers I like better. Perhaps Deckert puts some magic in his builds but with so few parts I do not see it. Tube circuits were perfected almost 100 years ago. Not much has changed since.

I gave that some thought as well, the nfb having some bearing but figures do not lie and the current you measured going through the two resistors is going to be constant no matter. If you use the distortion analyzer, Artar, or something similar you will have a better view of the changes you made. I assume no hotspot on the plates after changes, so you are safe for sure. Not sure how you decided value of resistance, through calculations or just data sheet but I used the calculator and put in the desired dissipation of the tube, 1.25W and the plate voltage and came up with the resistance needed. The data sheet does suggest 470 ohms so calculations were spot on. Running the 1.7W tubes at 1.25W is a conservative rating. I was hoping Maynard, our tube go to guy on this forum, would put his 2c's in this thread. I value his opinion.

I get only .0045W on that tube that is rated for 1.7W. Like you I think you could lower that values of those resistors. Om my calculations those resistors could be 250ohms each with a 1.25W on the tubes. https://ohmslawcalculator.com/ohms-law-calculator Check it your self with the value of the desired W of 1.25 and a total of 500 ohms. Like you I do not understand why such high value resistors.

What is the voltage drop across both 1K cathode resistors? That and what is the accurate resistance from ground to cathode of tube of the two resistors. With both those figures using ohms law you can determine the current. Knowing the current and the voltage at the anode will give you the wattage of the tube to determine how you are biasing the tube. The plate dissipation of the tube is 1.7 watts and 80 percent of 1.7 watts is the target value most designers shoot for biasing a tube.

I did not answer entirely correct on replacing those to resistors with wires. You cannot do that with the 470K resistor. You can just take it out and the stray electrons on the grid will find ground through the volume pot. You can just solder a wire across the grid resistor that can be easily removed to see if you really need that resistor. The designers I like try and take out all unnecessary parts they can. I do not see how it makes much difference where you put the grid resistor. There is no current on either resistor. The schematic does not show what rectifier tube is used and what I said was in general terms. If the data sheet for the specific tube used for the 5Z4 says 4mf that is what you need to use. But from what I see on the RCA data sheet for the 5Z4 it calls for less than 40uf so the designer of the schematic seems to know what he is talking about using a 35uf cap. https://frank.pocnet.net/sheets/049/5/5Z4.pdf. But if your amp is quite with just 4uf of filtering for the first cap you are good to go. I just have not seen such a low value used before but the 5Z4 is an old tube and back then caps were expensive so they relied more on a choke for filtering. One has to be careful on what to believe on internet sites. Data sheets usually are what you depend on when working with active components and not what someone says on a forum. Not all advice is accurate or good. One has to learn who to trust on forums before believing all that is said. That includes me as well. 🙂

I do not see anything wrong where the grid stopper is at or the first cap on the schematic. The first filter cap being 33UF is right, nothing wrong there. You do not want the first a with a higher value than 50uf with a rectifier tube or the Voltage surge on startup would be too much. Most use a 1K ohm resistor as a grid stopper. Modern designers are removing the grid stopper and the 470K resistor as well thinking any stray electrons on the grid will find there way back to ground through the volume pot. You only need the grid stopper resistor if one has oscillation, squeal. If you want to play some remove those two resistors and put in wire on board and give it a listen. Less is best in my world. I've built a couple of those Chinese kits with some issues but after solving they sound really good. Iron appeared to be really nice as well.

Edcor OPT's are bought with just one setting for speaker impedance unlike the ones I am currently buying, Hammond, which have many options one can use. In general terms any of the multiple taps can be used on any speaker, it just increases power with a lower setting with slightly more distortion and lowers power out with the higher taps. Whether the OP will notice a difference changing OPT's is debatable but IMHO subtle at best. One can change the impedance of the speaker by adding some resistance in series or parallel but it is not something I would do permanently but it is something one may want to play with.

You have a taste of what tubes can do. Now you can wonder what a really good tube amp would sound like with your speakers. 🙂