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Analysis Of Little Sweetie Amp


Curious_George

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As a separate topic for those interested in design or just how those funny looking plate curves mean anything, I have plotted some preliminary info on the 6Y6G/GA/GT plate curves. 

 

An additional tube is also posted (Courtesy of Matt from diyaudioprojects.com); 6EM7 with design data to illustrate how much info can be extrapolated from the plate curves.

6EM7-Plate-Load-Line-Triode2.jpg

6Y6GT Load Line.pdf

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  • 7 months later...

Well, thanks guys for the kind words!

There is nothing at all wrong with Maynard's "LITTLE SWEETIE" A really splendid design, I might add.

Without his inspiration, I would have had nothing to build on.

I like to build my way, and he likes to build his way. I'm sure both work and sound very similar.

If there's enough interest, I could supply CNC machined Hammond 6X9X2" aluminum mono-block chassis (as used by Maynard)

They would be ready to use, without any metal-working, just bolt on the parts.

I might at a later date, offer a partial parts kit that has tube sockets, IEC socket, on-off switch, fuse holder, mounting screws, etc.

Builders could then choose their favorite resistors, caps, and tubes.

I like to drill & tap all the mounting holes #6-32, which makes it very easy to mount all the parts from the outside of the chassis.

It's so much easier than holding a heavy transformer in one hand, and then trying to insert a screw and nut with the other hand from underneath.

Yeah, I'm a retired tool & diemaker that has my own wood-working, and CNC machine shop on the property.

I started building Knight Kits in high school, ca. 1962, and DIY around 2000.

A nice forum; fun to read and learn from!

Rgds, <JNL>

IMG_2667-1.jpg.a7ab83250262384b68ec908a30daa4a6.jpg

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17 hours ago, John N. Lumley said:

If there's enough interest, I could supply CNC machined Hammond 6X9X2" aluminum mono-block chassis (as used by Maynard

Rgds, <JNL>

IMG_2667-1.jpg.a7ab83250262384b68ec908a30daa4a6.jpg


 

That is a wonderful offer John.  I used the 9x7 chassis which allows ample room for maneuvering underneath.  One of the biggest deterrents for prospective diy-ers is the chassis prep.  I hope you get lots of interest!

 

Maynard

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OK, Mouser has 36 of these in stock; with the cheapest UPS-ground shipping, the cost is $41.75 for a pair.

https://www.mouser.com/ProductDetail/546-1444-972

Hawk is cheaper, but why buy there, when you can combine shipping of the electronic parts at Mouser, and save on shipping?

(one vs. two shipping costs)

I can ship a pair of CNC machined enclosures for $17.10, via a USPS flat-rate medium box, in the USA 48 states.

So, we are at a total of $58.85.

BTW, I have not marked up any the costs!

Now, I just need to estimate the CNC machining costs.

Perhaps a group-buy of 10 pairs might be a good idea to lower costs?

 

Rgds, <JNL>

 

 

 
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10 hours ago, John N. Lumley said:

Hi again, here's current NOS tube prices at https://vacuumtubesinc.com/

A reliable seller in Orlando, Florida, USA, that I've used for many years.

 

6SJ7         $7.50 ea.

6Y6GT      $3.50 ea.

6W4GT     $3.00 ea.

 

Rgds, <JNL>


 

I totally agree that Jim Cross, the owner, is honest and reliable.  I have bought all my tubes from him for more years than I can remember.   
 

Maynard

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On 4/19/2023 at 5:54 AM, henry4841 said:

Hard to beat the prices of the tubes for the Sweetie. Tube prices have risen dramatically in a relatively short time. Most know the reasons so I will not elaborate further. 

Hi Henry, thanks for posting.

If you look at current tube prices (NOT NOS), you might find that the old tubes are a bargain!

and in most cases, better sounding. YMMV

 

https://www.tubedepot.com/products/sovtek-6sj7     ($49.95)   

 

https://www.tubedepot.com/products/genalex-gold-lion-6v6gt-cv-511-power-vacuum-tube     ($59.95)     

 

https://www.tubedepot.com/products/sovtek-5y3gt-rectifier-vacuum-tube     ($35.95)

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  • 3 months later...
On 4/17/2023 at 3:59 PM, John N. Lumley said:

Well, thanks guys for the kind words!

There is nothing at all wrong with Maynard's "LITTLE SWEETIE" A really splendid design, I might add.

Without his inspiration, I would have had nothing to build on.

I like to build my way, and he likes to build his way. I'm sure both work and sound very similar.

If there's enough interest, I could supply CNC machined Hammond 6X9X2" aluminum mono-block chassis (as used by Maynard)

They would be ready to use, without any metal-working, just bolt on the parts.

I might at a later date, offer a partial parts kit that has tube sockets, IEC socket, on-off switch, fuse holder, mounting screws, etc.

Builders could then choose their favorite resistors, caps, and tubes.

I like to drill & tap all the mounting holes #6-32, which makes it very easy to mount all the parts from the outside of the chassis.

It's so much easier than holding a heavy transformer in one hand, and then trying to insert a screw and nut with the other hand from underneath.

Yeah, I'm a retired tool & diemaker that has my own wood-working, and CNC machine shop on the property.

I started building Knight Kits in high school, ca. 1962, and DIY around 2000.

A nice forum; fun to read and learn from!

Rgds, <JNL>

IMG_2667-1.jpg.a7ab83250262384b68ec908a30daa4a6.jpg

Allied Radio. , ftw. 😀

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