The "espresso v. Americano" analogy is great, I immediately get it. Looking forward to seeing how the Sarah plays in the real world before my order comes up. Could go either way of this but can't imagine I'll be unhappy either way.

Wathen offers cryogenic treatment for Decware products including the Sarah. When my amp is ready for shipment I’m hoping to have it sent to Don for cryotherapy. If anyone else is planning on this I would be curious of the results. It seems as if it will be long wait, maybe I’ll have a Herman to introduce to Sarah by then. His T-casters look interesting as well.
 
  Every now & then I know it’s kind of hard to tell, but I’m still alive & well,
Ralph

Can't wait to get my 300. I ordered many components in March. Was on page 64 then, and am on 34 now. Assuming this rate maintains, I'll have my hardware sometime this autumn.

Nice! I'm also saving for Cornwalls!

BlackBess,

I had my CSP3-A processed and yes it made a difference.  Simply put it disappeared.  Would I do it again???  Next month my UF025 goes in for processing.

I have had extensive experience with CryoTone and found that the ultimate results are when a full set of tubes are used.  One ore two will only give you an idea of what these can do. Sometimes the other tubes can get in the way.

I love the look of giant tubes. Is the 274b the largest, lightbulbesque tube I've seen on the Sarah? Additionally, is that the one that would utilize the full 7 watts?

Quote:


I remember a post by Steve, although I was unable to find it just now, where he said the 300B uses a filter choke that reduces the maximum capacitor requirement of the rectifier to 4 uF, so you can indeed use that WE 274B you have lying around. The big requirement is the rectifier is rated for at least 200 mA DC current.

With how long the wait is to get a Sarah & being intrigued by the cryogenic process, I’ve been wondering about Wathen’s Herman. A push-pull el84 all cryo-amp. Plus I always wanted to try one of those old Mapleshade modded Scott amps. Maybe a similar-esh experience. But the more I think, I try to remember, if you don’t think too good, don’t think too much.


I’m hoping to post thoughts on the Wathen 300B cryotone tubes soon.
BTW, old Bess has had cryogenic therapy.

Kamran, a lot of people are changing amps to the 300B I think. At one point I was #5 in the queue, now I'm #10. And the one that was in "Parts Pulled" status now is on the bench. Which I find exciting!

As of this morning 73 SEWE300B are on the list! It's already a "success" and no customer has one yet! Wow.

Will there still be an option to have the top plate oriented in a fashion, which displays the screen printing? I know Steve was having some problems with his screen printer, hope they got that sorted out. I much prefer the screen printed option. Looks awesome.

I just read in the manual for this amp that you can't use mesh 274B..

How does one differentiate between a "mesh" and not "mesh" 274B?  Is it part of the description?  

I searched eBay, and found a few offered but did not see a "mesh" reference.  

Thanks, Lon

Sadly I'm not possessing a great deal of knowledge about these rectifiers. The "mesh plate" is actually a description of the "plates" within the tube. Generally these are "solid" but several manufacturers make "mesh" plates, and they seem to have differing needs for resistors associated with them. The "mesh" seem to be most often used with 45 amps, and there are "mesh" versions of the 45 output tube.  The "mesh" will be short-lived if operated within other Decware amps, and in the manual for the SEWE300B Steve notes they are not designed for use.

A "mesh plate" 274B:



A "solid plate" 274B:

I guess so. I use the rotary head type myself when I don't use a wet blade.

They do light up and look bright in use!

Nice! I like the labeled transformer cover better than a silk-screened chassis.

Since I have to build another one I've decided to take you through this process as I go... as a nice way to complete this development thread.

So the first thing is to prep the steel plate by sanding off the powder coat in key locations so that the volume pots and input switches stay shielded and the power transformer is grounded to the plate.




These plates are 1/8th inch thick.  They are made in Addison Illinois.  The screeners are also from Addison but are a different company.

Making sure to mount it the correct way.  Nothing like finishing the amp and removing the tape to find you installed it upsidedown.

Installing sockets.  These are the best available in this form factor.  I've tested them all.  There are many sockets that look like this from a distance but the inside of these sockets have dynamic springs surrounding the tube pin for the highest contact area of any socket design.

I decided to flush mount the meters because on this amp, it makes it look more expensive.  Eventually these meters will be replaced by color coded DECWARE meters, but they are still months out so the first amps will be easily identified as being the ones with the white meters.

Adding the rest of the hardware.  Machined gold RCA jacks, and Red Copper binding posts.

Wiring the transformer wires to get them out of the way.  On the 300B socket the heater wires are soldered directly to the pins so there is no current going through the board.  Besides the current of the heater the heater is is also the cathode that draws additional current. The board is just there to keep the pin holders from moving.

The audio ground buss I have found to be one of the most crucial parts of the amplifier as it effects the sound, performance and noise. We use bare copper suspended in air.

With the audio ground buss established, it is time to bridge the audio ground to earth/chassis ground through a resistor and capacitor.  This holds the audio ground signal a few ohms above ground so that it becomes nearly impossible to have ground-loop hum.

Steve Deckert wrote on 01/08/23 at 00:20:06:

It's a unique and classy touch, fitting for this amp. Thanks for showing this assembly step by step.

A.  
Love seeing this process and love the transformer laser etching, but man, you're breaking my beard showcasing that silk-screened top plate. I love that look, it looks so sharp!

The flush-mount meters were a great call also.

Yeah, man, I get it. Sometimes a thing just wants to be what it wants to be. The Decware 300 wanted to be something different, and alas, it is. I respect it for what it is.