The DynaGrid Rectifier Design Log

New Product from Decware coming this fall.

UPDATE: 6/27/2025

After a year of reading the STR thread on this forum, I wasn’t surprised to find the sound can be noticeably better than a good 5U4G using the right tubes. Getting the ideal tubes for a specific amp or preamp kind of turns it into a power users game vs., something for someone newer to tubes.

Rectifiers, such as the 5U4G, introduce a natural voltage drop and nonlinear impedance, creating a "sag" that softens dynamics and adds a warm, musical quality to the sound, often perceived as richer and more engaging. This sag enhances harmonic richness and provides a smoother response to transients, complementing complex music with a pleasing compression effect.

Solid-state diodes, while more efficient and precise, deliver a stiffer, linear power supply that can sound clinical or harsh in some systems, lacking the dynamic interplay and tonal warmth that tubes impart. The exception would be something like the ZMA where you use capacitors that are 1000 times larger than normal.

To improve upon the average 5U4G rectifier meant exploring more and more exotic $$$ rectifiers until you end up with something like the STR.  


The natural voltage drop and sag of a rectifier is factored into the amplifier design and especially the amplifier voicing. But even with the factory original rectifier tube, as the voltage at your wall outlet changes up and down, the B+ voltage of your tube rectified amplifier will also change. This can be why your amp sounds a little different from session to session in some homes or apartments.

The rectifier tube will also drift over time. There is no way to know this, because there is no high voltage meter on amplifiers.  It would be nice if there were, and you had a way to adjust the B+ to not only the amplifiers design center, but outside of the design center to experience how that affects the sound so long as it is limited to a safe window of operation.

Another minor problem with rectifier tubes is that tubes do in fact drift and diminish over time. Since a rectifier has two plates inside they both have to be precisely matched.  If one drifts away from the other, there will be reduced performance and likely increased hum.  Using two separate tubes, or more, for rectification requires that they be matched and stay that way for optimal results.

Anyway, I wanted a single device, with a single tube to prevent having to match tubes, that would work for everything be it an amplifier or preamp. Basically anything that can use a 5U4G or similar. Say from 30 mA to the 5U4G max rating of 225 mA, one product that does it all.

I’ve taken a unique approach to this that has many advantages.  

This is what I’ve done:

I've replaced the rectifier with a pair of 3 amp solid state diodes that drives an 845 triode with adjustable grid bias to replicate the 5U4G voltage drop and sag characteristics but with infinite adjustability within a safe operating window so the voltage drop can’t be decreased or increased too much.

Additionally a soft start is built-in using this approach which is particularly nice for directly heated triode amplifiers.

The 845 tube was chosen because there are so many different brands available that it drives the price to as low as $50 a tube.  Also, rated at 100 watts the tube will rarely see 11 watts in this design and operates at well below half it’s rated voltage so I would expect it to last possibly for the life of the product.  This takes a lot of the cost out of ownership because the infinite adjustability eliminates the need to roll different tubes.  You can just dial it in, watching the meter as you go, and hearing the results in real time.

As an example; You might decide that a Sarah 300B amplifier sounds better at 380 volts rather than 405 volts with the particular tubes you’re running.  With the meter you can always see what the voltage is so if the wall voltage drops and your amp is reading 370 volts, you can raise it to your magic number.  Or if it’s too high, you can drop it.

So here are some bullet points of sorts:

Hybrid Approach: Hi current solid-state diodes eliminate tube rectifier failure modes, while the 845 triode provides tube-like sag and warmth, controlled via adj. bias.

Adjustable Voltage Drop: Allows real-time tuning of B+ voltage, avoiding the need for tube swapping and ensuring compatibility across all tube rectified amplifiers and preamps that would use anything from a 5Y3GT, 5R4G, 5AR4, 5U4G, 274B.

Monitoring: Both amplifier current and B+ voltage meters let you see how much current your amplifier draws with the tubes that are in it, and what the high voltage is at in real time.

Simple Design: A single 845 triode that almost never wears out with two meters a power switch and a knob to adjust the voltage drop.

Thermal Efficiency: External heat management and diode efficiency lower amplifier temperatures, enhancing component longevity. For example, the Sarah amplifier temperature dropped from 128’F to 110’F.

Dynamic Response Control: Adjustable bias mimics tube rectifier “sag” or provides a stiffer supply, offering tonal flexibility not possible with the 5U4G or fixed aftermarket rectifiers.

As you can see, this design log (unlike previous ones) jumps into the design after it has already happened.  I’ve been testing it for 6 months or so, and it took about that long to design it to function the way I wanted and be completely safe.


I can confidently say that no rectifier tube I own can touch it sonically, it's sooo meaty and holographic... even my collection of high dollar 274B’s do not sound as good. And to even have a collection of high dollar rectifiers means you have also had some blown ones because so many come from eBay and China.

This will be the rectifier tube that can’t be bested at any price and lasts for life.  Additionally it will likely increase the life of all the tubes in the amplifier, show less stress to the transformers, increase capacitor life, and lower the heat of the amplifier, so again if you run exotic tubes in your amp, this could easily increase the usable lifespan.


I’ll post some pictures of the prototype in here eventually and the production units as they come along. I’m on the very tail end of the design process so I expect it to go into production this fall. There could be two models, I haven't decided yet. Pricing is still up in the air, but it would be competative.

The  (C) 2025 name DynaGrid comes from Dynamic Grid Controlled Rectification. As far as I can tell, nothing like it exists in the world making it a world's first!

-Steve

Very interesting.

Sounds so interesting Steve. Other than price, my other question is will the wait time for this device be less than four years once ordered.

Fascinating Steve! I'd much rather consider this than the STR. (Though I am still not sure that I am wanting this sort of device, nor that I will be able to afford it).  Will be so interesting to see the final model(s) and pricing.

Very cool! This brings up a question:

CA, with monoblocs, how would this be connected? Would you need one for each channel? How is the STR setup with dual amps?

MM wrote on 06/28/25 at 15:05:38:


It's just a (hopeful) guess. . . but this may be on the accelerated list rather than the amplifier list. Time will tell.

Lon says;
"It's just a (hopeful) guess. . . but this may be on the accelerated list rather than the amplifier list. Time will tell."
     

Or place order now for anything and then switch to DynaGrid when time appropriate ??

I knew it! Deposit down and back on the list!

Mental Notes:

1) Given the popularity of the STR, I was wondering when Steve would offer something similar? I would much rather get something from an outfit that is well oiled and established, from an engineer that I know and respect, and a customer service situation that doesn’t involve being dependent on the whims of one individual. Not meant to be disrespectful of Al and what he has achieved — you know what I mean.
2) Missing/Craving a new development thread!
3) Amused that the two biggest STR holdouts just perked up!

How Steve kept quiet for six months is beyond me! Looking forward to more updates!

Kamran said, "How Steve kept quiet for six months is beyond me!”

So, note to self (and all of us) - don’t play poker with Steve.

Randy

This is very interesting for sure. Hopefully not a 3 year wait but it surely don't look like a black box!
What happen to the ZCA Steve?

I would want to know what you are hearing when used with amp x. I am interested in use with SE84UFO25 and Torii Jr V2. Hopefully, you will share more over time.

Do you limit development in short term to single rectifier products for ease of manufacture and product launch? It seems to me that you would benefit in the short term to limit the product initially to Decware products. You obviously know the safe operating window of your products.

Your comment about a 300mA meter in the production model. Will this fit the operating range of your amps/preamps? Do premium meters matter? Power supply design considerations? If I am running a preamp and amp, where would I get the most benefit from a DynaGrid?

I only see one knob. What does it adjust? Are amplifier current and B+ voltage related as you adjust? You made comments (as an example) of running a Sarah at 380 volts instead of 405 volts? Based on your comments of wall voltage dropping reading to 370 volts. I think wall power stabilization could be an issue. How should owners tackle this issue? It seems like something more than a ZLC is needed. What are your thoughts?

Can you tell us more about the power in your listening room? Do you run dedicated circuits? Use ZLC?

Monitoring is a benefit, but how does one take action based on what one is seeing from a amplifier current or B+ voltage perspective?

Is the cord to the rectifier port detachable? Do different cables even make a difference?

I do not understand a lot of technical speak about how some 'things' work. But there is no doubt in my nowadays 'dented' mind, that when Steve has his mind set on something, it's obviously going to be a winner. So fn talented. I will try not to get too personal on the internet, but I got in on Decware when the Zen UFO2.1 amp I ordered (my pretty wife made me get it! She saw me reading about them several times) wound up being a wait time of 2 years. I had already been through 2 very serious, more recent hospital stays, 3 years apart and a total of 3 'episodes' in my life, so because of this, I was paranoid about ordering. I was SO blessed to even ~BE~ at all and no one understands how I am still here. Especially me.   Other than my family and friends, this wait on this amplifier was so exciting to me. There are some things I can no longer do, but listening to good music.... always so important to people like us too. Our little Zen amp IS the best electronic music purchase in my lifetime. For those of you that are financially able and healthy etc, order what you want here. The wait is sometimes the pits, but weirdly exciting too at the same time. How do you explain this? I am currently getting ready to fire up the music in here for a bit. This happens a LOT. All the very best to Steve and ALL staff over there. As well as this forum that has such wonderful and helpful people too. It's not about me, it's about YOU folks waiting to order, like I did....if you can swing it~ think a bit more about it and just do it. I told my way better half to be glad I was once as sharp as a rocket scientist...pretty sure she never bought it though...  Always~  Mike

Mike, Hock--I'm with you both. Music is what keeps me going, looking forward, get through the morass of insanity in the world. And Decware components have been with me for nearly 30 years now, they've gone through the changes in life and fortune that I have and I have reached a plateau of beautiful sonic playback that sustains me and calms me. I owe a lot to the Decware family and to this community of forumites.

Are we going to be able to listen to this at this years Decfest?
Bob

The unit is designed very specifically for the 845 tube ONLY.  If you want to roll tubes, there are probably 50 or more different brands ranging from $50 to $1900.

I am doing all of the testing with $100 Linlai 845 tubes, which is what it will ship with.

Steve

Wow, this is really exciting. As someone who recently acquired an STR I would love to hear how this pairs with my SE84UFO and compares to the STR. I'm sure competition for those first 10 will be stiff, but here's hoping.

I also love the idea of a single 845 tubes but there is something truly magical about the STRs 866A both visually and sonically that would be hard to give up.

and for us two 5U4G per amp users, i.e. a Torii, do we need two of these, or will there be a "dual" model?

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I like this idea. Imagine a premium version of SE34I.6 with DynaGrid built in. Put in the 845 instead of a rectifier. Add two more meters and eliminate headphone and four input option. Maybe use a Torii chassis? Make it an all out assault on what SET could be. Probably too good to be true….

How about a SE84UFO25 in a bigger chassis with a DynaGrid and other tricks or options that could not be done in current chassis? Dual power cords?

I guess my question is what is next for Decware? What else is in the design queue? How about a 150 watt solid state amp with a DynaGrid build in or tube rectification?

Solid State Amp at Decware? Gasp!!! Blasphemy 😁

From a manufacturing perspective, making a single Dynagrid just makes sense. Will have to buy 2 for my Torii just as I had to buy 2 STRs.

Sign me up..............

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I expect these are the same diodes he uses in the power amps.

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This is something I've always wondered about. Is the "rectifier sound" just due to the voltage drop in different rectifiers, or is there more going on? I suspect it is the latter, but it will be very interesting to hear everyone's experience.

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I think it would have to do that. The difference between the voltage for a power amp and preamp seems like it would be too much for the DynaGrid to have a fixed voltage built in.

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Appreciate the encouragement!

Being new to Decware, and the forum, I’ve only been privy to the thrill of reading the design log for the ZCA somewhat live and it truly is exciting to feel like I’m part of something new and groundbreaking.

As I was contemplating purchasing a pre-enjoyed UFO25, I stumbled upon Steve’s design log for it and read every single post.  The melancholy I felt upon reading the last post was akin to finishing the last book of the Lord of the Rings trilogy. Okay, maybe not quite that profound, but the journey of discovery Steve describes is so intriguing.  I was really bummed the ride was over!  

And I really appreciate the comments and questions from you “old timers!”

Yes, this will be available in both 120 and 240 volts.

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Would that be similar to using 0C3 or 0D3 VR tubes for the power tubes on a UFO25?

I find that to be the case with my SEWE300B and I think of it as "natural compression"--more gain coming into the amp with the gain of the amp turned down, tends to damp treble energy as if the signal were "compressed" by a compression device.

Every room and every set of ears is different. I wrote it like I hear it and understand it. I'm not an engineer and I don't have an affinity for engineering. So. . . that's how and what I hear where I am upstairs here in my expanded 1918 cabin home.

Same here, Lon. Just sharing what I hear and trying to understand my audio experience more.

Thanks, James. That does help. Once I think about it from the tube perspective it makes a lot more sense.

Loving the sound coming from my system today, regardless of!

I am presently working on the DynaGrid Jr.  It is the same unit without the adjustable voltage drop.  So far it's going well, mimicking the 5u4G voltage drop pretty closely on everything from the ZP3, to a TORII JRv2 to a Sarah 300B, which I had originally determined was impossible so I'm pretty happy about that.  The sound is exactly the same assuming you have the adjustable one adjusted to match.  This unit looks identical, but would be half the price and take far less time to make.  

Yes, it works on all Decware amplifiers, and should work on all components that use a 5U4G rectifier, but I am still in the process of testing it.

Here is a list of the rectifier tubes that the Dynagrid could replace:









The exception is the 5V3A and GZ33.  While the Dynagrid can handle the current and higher voltages likely to be found in amps that use these rectifiers, I don't plan to make the voltage meter on the DynaGrid that go that high.

This is an impressive set of rectifiers and its nice to see, at the very least, there has been a lot of thought about how the DGR works across multiple rectifiers.

I wonder also how it might fit within the chain in terms of sound quality. Since it seems it will work on a phono/pre/dac/amp or wherever there is a 5U4 type tube, what might be the advantages/disadvantages or sound qualities be when you move it around to different components. I.e. does it sounds the same run from a preamp and a power amp? How does it sound if you run two? Or, if you have 5U4 rectifiers on all your components, what if you had a DGR on all of them?

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The answer involves testing links in the chain to find the weakest one.  The weakest link in the chain sets the fidelity.  If you eliminate the weakest link in the chain, you will create one or two more albeit less compromised than the first and so on it goes.

If I design or redesign any more amplifiers, this is likely to just be part of it.  I can only imagine never having to hear about blown or arcing rectifier tubes again, or having to educate people that they need to be changed regularly in higher power applications.  While an 845 tube is expensive, you'll never need to replace it.

GS, if I didn’t live in the desert, where tube heat is a consideration, I would wholeheartedly second your request to Steve.

Randy

Hey all!

...just popping in to check out the DGR thread. I just had told myself I was too tired to write a bunch about this at the moment...Iguess I couldn't help it! oh well, here it is

I haave been able to give them a listen a couple times now, and I really like what is going on with this project. My initial introduction was to the DGR Sr. on the digital rig. The smoothness was eerily impactful... when I noticed the blackness in the background and general ease of presentation of an after dark listening session during the daytime with the entire building buzzing with noise... I made note of it. But, that was the digital rig... if the digital rig sounds that good... {at this point, please envision a brilliant shaft of light shing through the Decware listening room window falling perfectly on Steve's modest turntable on the other side of the room...} [Thanks:)]

BUT WHAT WOULD IT SOUND LIKE OVER THERE!!!!

I love a good surprise, so I tried not to pry too much after I saw several prototypes in and out of the room and adjustments being made... a tinker here... a tinker there...

Two Tuesdays ago my patience paid of and listening nite was a surprise introduction to the DGR Jr. onn the analog rig... I was super stoked!! Our freind Ian had brought in some real nice cuts from his collection and it made these records really vibe. Unfortunately, there was not much known (to me) material played that night, so I didnt get a real good feel for it initially, but I noticed some things I thought I might really like. So this week I came loaded for bear and really threw as much of my referance cuts at it as I could and it was very rewarding.

I meant to chime in on this a little sooner... better late than never, eh!

Cheers

Awesome to hear Steve! Looking forward to seeing this come through. I’d be super curious to hear ultimately how different the DynaGrid sounds vs. my STL-MK104s (Space Tech Labs’ entry level “Super Rectifier”).

After a brief foray with Mercury Vapor 866a tubes, now settled in with Xenon tubes 3b22 and 3b28 on each and plugged into the Torii MK V.

Can’t wait to see this one released!

Do we have an indication of the price of the full and Jr versions yet?

Thanks

... just reporting back to the thread now that I have had time to be able to hear some of my reference albums on the DGRJr. I have been able to sneak in a few sides here and there over the last couple weeks and have been very pleased (as usual).I now have had a chance to hear my current solo acoustic instrumental reference album side A of Keith Jarrett's Koln concert (Japanese Original Pressing, PA-6053-54, IIRC), along with side A of Art Pepper meets the Rhythm Section (180g, CR00491) to round things out for acoustic group recordings.

It took me at least a half hour to recover from the Keith Jarrett. It shook me. I may never be the same, actually, but at least I can focus now. Between the very real feeling of the size of the venue, which I actually have no point of reference for other than the tone of the record, and impact of the of the more punctual notes the timing, soundstage, and depth of field was completely locked in. Given a blindfold, I would have a problem betting money on if it was a live performance or not. SO stable you could almost walk around the piano.

Just looking back on it I am still a bit worked up.

That's all I have for the moment... carry on.


Modifying the post just to add... that as far as the technical aspects of the DGR are concerned I am not as intimately familiar with these things as say, for example, Steve, but from the user end experience there is nothing "Jr" about it. This is an amazing addition to already amazing gear. I am really excited for it's launch so I can hear about all of the customer experiences with it.

I have heard the jr on the analog side of the room, and the senior on the digital side of the room Both running through the 300b on their respective setups. IIRC.

I try to understand, and you know I am rather thick  [smiley=icqlite21.png]
It seems that "sag" is beneficial in tubes amp because it brings "wanted" lag and distorsion, the kind valves officionados love so much. Hard to understand but let it be.
Now this device would cancel this sag, am I right ? To me it sounds good but to the majority of tubes fanatics, it should not. I don't quite catch it.

The chassis have arrived and look great.  They are stainless steel with our standard black powder coated finish.  I hope to put the first production model together this week.  

We have been listening to the DynaGrid Jr, exclusively for the past several weeks on the Sarah 300B and the UFO25.  I have been throwing New Old Stock 5U4's, the Decware 5U4's and some $400 Chinese 274B's by Linlai and PsVane at these amps for some time.  They all sound good.  I tend to favor the 274B in the Sarah, which is what we were listening to tonight.

I frequently use the Dynagrid and then go back to rectifier tubes in a spontaneous cycle.  We have had several concurrent Tuesday night sessions using the Dynagrid so tonight I removed it and re-installed the ACME 274B without telling anyone.  This is where it gets interesting.

The night started off sounding OK but not great.  I looked around and everyone was more or less digging it, so I blamed my cold for the sound.  It was good, but not one of those 'amazing' nights that are common around here.

As the night progressed we put the third album on and the band was fairly hard and complex.  It sounded a little dry and small and I thought this is going to be one of those LP's that doesn't do a lot for me.  The sound was off.  It needed help.  This kind of music doesn't work when it gets lean or dry or flattened or pinched or dehydrated.  Always blamed the recording since everything else sounded better... (foreshadowing)

It hit me that this would be a perfect LP to test the DynaGrid on and see if anyone can hear the difference.  So I cued the stylus off the record, and turned off the Sarah amp, pull the hot rectifier tube out with a cloth, inserted the DynaGrid, turned on the amplifier and then the Dynagrid.  It was basically almost a hot swap with the volume on the amplifier at 2:00.

I put the needle back down in the same place on the track and the difference was so obvious I didn't even have to ask.  It literally fixed the record.  Of the three we listened to, this one was definitely going to be the worse sounding one, and it went to the best sounding one.  I was surprised, as was everyone, that the difference was that big.  

With the original adjustable DynaGrid it was easy to attribute the improvement in sound to your adjustment of the knob and subsequent voltage drop.  With the DynaGrid Jr. there is no adjustment.  It just mimics the stock voltage drop of the rectifier tube.  So while increasing the voltage drop with the original model may add some sweetness, this time there was nothing but the design itself, a far more honest AB test.  

Anyway, this is about the third or fourth time I've made myself less than thrilled with the sound of the amplifier when running a stock rectifier tube,  even a $400 one.  Proof that everything is relative and you can't un hear things.

The best way I can describe the difference in sound between the $400 ACME 274B in a Sarah, which was one of the better sounding so far, and a DynaGrid Jr. in the Sarah, is like going from LP to a master tape.  The extra density, body, space, ease, dynamics, realism clearly demonstrates that rectifiers are a weak link in the chain.

If I build any more amplifiers, this will become the standard way it is rectified.  There isn't anything that is going to sound better, and the tube will probably last as long as the amplifier so you have double the juicy benefits of a tube rectifier without having to tube roll, or deal with arcing rectifier tubes.

I'll keep you posted.  Sarah has a list of the first 10 so we should be able to get those out this winter.

Steve  :)

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It doesn't "find" the sweet spot, Steve picked a sweet spot and hardwired the DGJr to that value.

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Technically every tube rectifier chooses a different "that" point. So "that" is one of the things you alter when you roll rectifiers. The DGR is special because it gives the user real time control over "that" point with a knob. For the DGJr Steve picked "that" point, presumably based on what he likes and typical tube rectifier performance and the only adjustment is through changing the 845 tube. It does not make adjustments on its own. Just as the only adjustment with traditional tube rectification is changing the rectifier tube.

One thing that might not be clear is the input/output voltage to/from the DGJr is determined by the component to which it is attached. So while "that" point it fixed, it is fixed relative to whatever B+ the component provides. Output B+ would not be the same for different amps/preamps/etc.

Just curious, but on the SE25, since voltage can be changed with different VR tube, does the Jr. have any effect?

Finally got some time to post…I’ve been off the “grid” (pun intended) latley due to work commitments.  Anyway… when I first started my journey into tube rolling pre Covid with my Torii MKIV…I bought a NOS rectifier and was amazed.  There is no doubt that Steve’s new DynaGrid is going to be a game changer allowing the user to make adjustments on the fly.  I could see myself buying one down the line.  I would love to use them with a pair of my SE84C+ Zen amps configured in a mono setup, but that would mean I need to buy 2 DynaGrid’s  😮. I can’t wait to hear the customer feedback once these are sent out.

Dom

Would the Elrog 300b’s be compatible with the SEWE300b using the dynagrid, since it’s easier on tubes? I’ve never wrapped my head around the Elrog incompatibility with this amp.

Maybe “incompatible” is not the correct term, but my comment came directly from Elrog. I tried to purchase a pair of their 300b’s and they said they don’t recommend them for use with Decware’s 300b.

Otherwise, yes, I have enjoyed Elrog tubes in other tube amps I have owned. Perhaps pricey, but rather clean across the spectrum, durable, and consistent. But, I also prefer generic Russian tubes in a UFO over Elrog tubes in other amps I’ve owned.