Hopefully you'll never experience this, but when a rectifier is badly suited for its application or aging. . . or whatever just sometimes . . . When powered on there's a little arc, a tiny lightning bolt if you will, that flashes within the tube--I usually see it happening at the top as I turn the amp on either from the regenerator (main system, amp on lowest shelf) or switching on while standing over the amp or preamp which is low down on a stand in my other two systems, and I'm looking right down on the rectifier.

It's not a good thing, a scary thing if you have an expensive fuse in the amp!

An AC heater will alway have more noise than a DC heater and can be seen on an oscilloscope or heard if you have very high sensitivity speakers. Some people say that AC sounds better if the design has a relatively low hum, and based on your speakers and seating distance...and sensitivity to it.

That's what I've read too Junker. I'm not sensitive to hum as far as a tiny bit of it bothering me, but I can hear hum pretty clearly even at very low levels. That's been my experience with tube amps ever since my Dad's Dynaco set-up of the early 'sixties through the early 'nineties. I almost always here a tiny bit. The notable exceptions being my CSP3 and Taboo IV with the Anniversary mods--with headphones those are dead quiet. The Monoblocks are pretty darn nearly hum-free with the HR-1 speakers.

It may well be that the Sophia Electric Classic 300B (which were bought as a demo pair, so not brand new, unbroken in entirely) are the source of the hum. I don't have any other 300B to compare. Either way I'm perfectly fine with the tiny bit produced.

Referring to Sarah's hum, Ghostship said

I'm not sensitive to hum, so long as it's not annoying from my listening position, I'm fine. It's just that Steve made mention earlier in the thread that we could expect a slight amount of hum from 100dB speakers...and that prompted people in other forums to conclude that the Sarah is a poor design that hums...

I would not think of design flaws, but this report concerns me as one who is sensitive to hum. After 12 months of waiting in line and another 12 to 18 months to go, I would be crestfallen if I could hear a hum from the listening position. I have had three Decware amps, and they all have some hum, but not from the listening chair. In one case, it took a lot of room treatment, but it quieted down.

Good to hear that it might be managed by tube choice. Thanks for the report. For me, an important topic to follow.

Junker wrote on 07/25/23 at 22:04:28:


They may. They are just copper-plated though, not entirely copper, not sure how much would make a difference.

I’m pretty sure it’s cosmetic only.  That said, I’m having a change of heart (the copper has grown on me) after looking at endless pictures and I’m planning on upgrading.

On the subject of hum, is the hum pot making any impact?

Well, I'm not the definitive word, perhaps Steve will set us straight. I had assumed it was copper made but when this was first discussed the consensus here seemed to be that it was electro-plated. But I agree that it is expensive for that. . . though I have to say beautifully done, no question there. And no matter, I'm very glad to have them on mine.

Copper plate top. . . not sure. I actually think this top plate is my favorite of all those offered by Decware. Looks great in person.

I'm about to go to bed so I'm not going to or able to search the thread for what may be there. I bet you can find it one way or another. See you on the other side.

Quote:

Yes, the hum pot knobs work. With the economy tube set I had zero hum, even with my ear right up against the speakers. When I swapped in the WE300Bs there was a hum, and the hum pot adjustments reduced the sound significantly, but not entirely.

Then again, hum can be caused by many sources. You can induce hum with these knobs to hear what it sounds like, then remove it again. The hum I was getting from tubes is clearly at a different frequency.

JBzen wrote on 07/26/23 at 08:30:54:

Thanks John.

That's a huge tranny and big end caps. Looks so formidable!

Quote:


No, the hum could not be heard from my listening position, which is less than 9 feet from the speakers.

I believe good quality cables, such as those sold by Decware, will decrease the chance of noise reaching the speakers, and contribute to a blacker background/lower noise floor. Of course, these aren't made by Harry Potter, so you have to do your part to eliminate sources of noise as much as possible too.

I was thinking a little more about the power transformer, and actually I think I understand why they did it the way they did. While copper would be a good RF (Gaussian) shield, I believe they need good magnetic shielding in that application which would require mu-metal or soft steel. So, the way they did it probably provides good magnetic shielding with the attractive appearance of copper.

P.S.: Also just FYI the Western Electric End User Guide recommends using an AC heater as it prevents electromigration, electrolysis, and potential voltage gradients that can affect transconductance performance.

Quote:


Not just Sarah. Given the hundreds of amps Decware has shipped in the last year or so there aren't very many new faces anywhere. I suppose they are too busy listening to music to bother with a message board.

Wow, when I first got this amp I didn't hear much difference between the two speaker ohm switches on the amp and just decided on one.  

Today, on a lark, I decided to try these switches again. Immediately the other position sounded more laid back and the sound became easier, relaxed. That's how I like it! It's going to stay that way. I tried the "bias" switches in the front of the amp and still prefer the "back" position.

This amp is sounding better every day. If you're in the queue for this one I would be very surprised if you didn't immediately feel it was worth the wait.

Yes, I know you're zest is in the other direction. I can't handle the treble energy there, unless I can sit much further back than the nine feet I'm forced to in my house.

There are so many possible "amps" in any of these designs. I can't imagine being locked into the sound of a solid state design again--these components are like chameleons or shape shifters and we can each find our bliss.

It's really a feature that can't be overstated, and I don't know of any other amplifier manufactured this way.

Usually, tube amps require a specific set of tubes to sound their best. Meaning, one set of tubes and it's as good as it gets, and with other tubes the sound ranges from less good to unlistenable; like putting lipstick on a pig.

Worse yet, when you purchase that amp and equip it with the Goldilocks tubes, you either like the voicing and sound quality, or you don't. Or maybe a better analogy would be you put the best shoes on her feet hoping for Cinderella, but the best you can accomplish is one of the step-sisters.

But with a Decware amp like the Sarah, it's like speed-dating Victoria's Secret models. From the settings of the ohm and bias switches, to the potential voltage drop of the voltage regulator tubes, and the rectifier, and the input driver stage, and the main input, to the brand of output tubes...every version is equally gorgeous. So you may have Behati Prinsloo in jeans and a T-shirt, or NOS Gisele Bündchen in a little black dinner dress, or Rosie Huntington-Whiteley in one of your dress shirts...you will find no room for complaint or disappointment.

The benefit is, you can be assured you will discover a combination perfect for you and fall head-over-heels, and spend the rest of your life listening in total amazement at your good fortune.

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We are already lusting after the amp and now this—-lol Ghostship—-you’re playing with our collective sanity!

On a serious note—this talk of two different settings on Sarah (laid back vs. more forward with bite) reminds of the A/B switch on the ZR2.  So my question is—how is the switch different from what the ZR2 is already providing.  To put another way—-if you like the forward switch position on Sarah, is the B setting on the ZR2 pushing things too far?

Man I am getting great sound yesterday and today. The amp is seasoning in well, and the new transport I put in place of the one that has the cd stuck within it has opened up from its long time of un-use (it sat unused a few years before I bought it according to the seller, it was not even fully broken in).

As a result I did some more experimenting with the tube complement to see what can be unfolded. I thought that the 7308s I was using as driver tubes were being a bit too "exact" for the present state and I swapped them out for the red-tipped 6N6P that I had been experimenting with early on in the process. That opened up a wide sound-field that was just a little "undefined" as far as imaging but really dynamic and textured. So I hunted through the four dozen or so 12AU7 types I had and found (stored incorrectly) one of the first 6085 tubes I had bought, an Adzam made in Holland, that was orphaned as I accidentally broke the other tube it was matched to, and I had been using 6085s as matched pairs. Well this is the warmest yet very focused of the type I have and it immediately dialed in the sound to be a rich and layered panorama . . . I'm getting the best sound yet.

Like the Monoblocks I bonded with so deeply this amp is a chameleon--it responds to every tube change. As I have only one pair of 300Bs, and a rectifier designed to work with them that does nobly, I have viewed those as anchors. I think the C751 and 2 0A2 are serving as a fantastic "foundation" for the input and driver tubes, so it's been the input and driver tubes that I have been paying most attention to. Which has proven to be rewarding--this is sound that rivals the best the Monoblocks have delivered, yet in its different, graceful way. This is one fine amp!

Two things that I have come to realize and after mulling over accept as near truths. One: this amp is seductive with its sense of power in comparison to the Monoblocks. With the Monoblocks I was always conscious that I had a limitation that I needed to work within. I did manage to do so and get exquisite sound so I relaxed into that. With the SEWE300B there seems no ceiling to worry about banging into and as a result I think I ease into the sound a bit more, rather than the sound itself has more ease. Secondly, the very nature of the Monoblocks adds a definition and precision to the sound that made an almost stereoptic vision to the sound, a bit more depth, and a more completely defined center that distinguishes itself. The SEWE300B in contrast has more center "fill" and a more blended soundstage that stretches across more than flows behind. This is not something that will hit you over the head, it's something noticed over time and it's as easy to be involved and enveloped with this "character" as it is to the Monoblocks' "character."

I love both of these forms of amplification--truly phenomenal designs.

I have about fifteen years of experience using voltage regulation tubes in Toriis and Zen Monoblocks and this guides my listening. I base my decisions on past experience and listening (which amounts to about the same thing).

Honestly it seems my experience that in general each tube type responds with some consistency to the differing voltage from the regulation tubes. So the voltage regulation tube combo seems foundational to me, and after finding that general character to the sound I can roll input and driver tubes for more refined tailoring.

The voltage regulation can impart character similar to the bias switching. If I preferred a big bold sound I'd use 0C2 for the output tubes, they would give that nature to the overall sound. I don't; I find I like the lusher, less "forceful" sound that 0A2 can deliver. In the larger voltage regulation tubes I like the sound 0B3 can deliver for power tubes, but 0B2 don't quite have the same allure for me for input and driver tubes.

In the case of the SEWE300B I'm hampered by the fact that I don't have one tuning tool I've relied on, the Treble Cut Circuit, and I need to combat the over-ripe treble that I find to be the easiest frequency balance to find. (That's the reason I avoid Wathen tubes because the input tubes I did try had far too much treble energy for me.) I can't do room treatment or change my ears so these other adjustments are what I can rely on. Certain voltage regulation and bias settings are de rigeur for me, and also settings on the P15 regenerator.

My personal cross to bear is this reaction to high frequencies. It is one reason I am so happy to use Decware systems which allow for tailoring of the sound. I am able to do without the Treble Cut Circuit on this amp--which Steve says he cannot provide--by careful choice of tubes and settings. And years of experience help me to get "in the zone" quickly.

Interestingly in this thread Steve said at one point he favors the 0C2/0A2 x 2 combo of voltage regulation and he also settled on the 6N6P tubes, those are where I found the foundation for voltage regulation and driver tubes. I'm sure you'll have fun finding your tube complement.

Shake it up!

The amp seemed to move to another level of sonic clarity and with talk of voltage regulation tubes and their effects I did a little rolling and reversed the set up, an Amperex 0A2 for the input tubes and a pair of Mullard 75C1 for the driver tubes. And I swapped the 6N6P for a pair of Amperex Holland 7308. This allowed me to use the "Lifted Ground" setting on my DAC which yields a glowing resonant sound to the playback that is just a shade bass-light. These voltage regulation tubes and the 7308s almost eradicate this bit of lightweight bass sound. I'm letting this simmer in as I listen to wonderful music I'm familiar with as well as a few new acquisitions that have arrived lately.

This amp really delivers with its flexibility and it's dynamic signature. And it's thoroughly a Decware amp, the house sound is unmistakable.

Present combo:

1 each Amperex Holland 12AU7
2 each Amperex Holland 7308
2 each Mullard 75C1
1 each Amperex 0A2
1 each Sophia Electric Aqua 274B
2 each Sophia Electric Classic 300B

I have over 300 hours on the amp and I've a better handle on its operation and sound and it is sounding very very good.

As is my source, the PS Audio DSD DAC Mk2, which was given a new firmware update that not only improved an already excellent sound quality but has offered new settings that improve the sound quality, such as powering off all inputs but one in use and turning off the Wifi.

As a result I experimented a bit yesterday morning and swapped out the voltage regulation tube for the input tube to a Mullard 0B2. This just dialed in the frequency balance right where I want it to be. For now it's a great choice and is dishing out the goods.

Tube complement:

1 each Amperex Holland 12AU7
2 each Amperex Holland 7308
2 each Mullard 75C1
1 each Mullard 0B2
1 each Sophia Electric Aqua 274B
2 each Sophia Electric Classic 300B

It's going to be some time before I try more 300B tubes. I've had a summer full of appliance and component problems from oven, dryer, transport and last week my laptop had to be replaced. I'm enjoying a brand new laptop that is better than I've ever had, but it cost me more than a pair of WE300B and took away all that money and more from my audio budget, which already shrank in May when my wife stopped working. That said, I'm very very happy with these Sophia Electric and my tube-rolling shows me that it isn't hooey when the brand says they were designed to work with the Aqua 274B--these two tube types fit hand in glove. My next tube will likely be the WE300B, so quite a way down the road from now. I'm too gun-shy to try the Wathen.

There have been a lot of variables in play since the amp arrived: new tubes mixed with old, another transport in play, new firmware for my DAC. It does seen that most of the "shifting" of sound characteristics has slowed and I'm very happy where they have slid into right now, though I do have the feeling from past Decware "Anniversary modded" components that there are going to be subtle changes ahead a few hundred hours or so, probably another month.

Overall this does not seem to sound like the only two 300B amps I heard before--it's a Decware amp, no question, has that clarity and speed. It also does have a bass heft and smooth treble and open midrange that I know the 300B tube is contributing to and that allows me to do without the treble cut circuit, though I'm nearly maxed out on ZROCK2 adjustment.

I've been playing a lot of material relatively new to me, and also material that is very familiar and I have to say I don't really hear shifts between dull and open this far into the break-in and that the character of the playback is accurate in comparison with the also accurate Monoblocks. I haven't gone beyond putting a ceramic fuse in when the glass one blew in the first seconds, so I know a fuse will be another territory to cross and map. In time. I have a relatively inexpensive fuse to try first, and then I'll try a heavier one if I feel the itch. . .and when the funds have slowly stacked up enough.

I do think the preamp stage is part of why I am getting the tonal results that are pleasing me, and I'm sure that the ZTPRE is a great feeder to the amp from my source. All in all, I'll miss my Monoblocks but I can't keep both them and the SEWE300B, and the SEWE300B is going to stay.

Yes. . . it breaks my heart though. But I can't use both, my two other systems are just right and there's no physical room for Monoblocks there.

What they said. Glad you and Sarah are so happy together.

Kamran, I thank my lucky stars Steve developed the ZROCK2, I have one in each of my systems, two fully loaded and one with just the Jupiter 2 caps as an option.

Don't look to me as an answerer as I can emphatically say I don't get the sounds that I do (and prefer and enjoy) without the ZROCK2 and as I have balanced sources the ZBIT. Others may not need these. I do.