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The long awaited "Little Sweetie" mono SETs

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3 hours ago, Deang said:

I once had a pair of the highly touted Wright Monos (2a3), and thought they were the most anemic, flat sounding amps I'd ever heard.

 

Something wasn't working properly (I know it couldn't have been the crossovers!).  There are guys running as little as 1/3 wpc from triode strapped radio output pentodes into La Scalas or K-horns in small rooms and the sound quality is beyond exquisite.  As Richie pointed out, listening level is the key point.  But, given how much acoustic output one can get from the above mentioned speakers, it doesn't take much to get blown out of the room. 

 

Maynard

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The preamp was a Quad, which used a single 6n1p. Output wasn’t issue so much as quality - which was lifeless. I understand synergy all to well - so it could have been the preamp (which worked really well with the Quad two-forty monoblocks). 

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Guest wdecho
9 hours ago, Deang said:

The preamp was a Quad, which used a single 6n1p. Output wasn’t issue so much as quality - which was lifeless. I understand synergy all to well - so it could have been the preamp (which worked really well with the Quad two-forty monoblocks). 

Something was not right for sure. I can understand your disappointment better now that you mention quality rather than quantity. I have a number of builds that just did not cut the mustard as well. I tear them down and recycle the parts for a better design. When mentioning my flea watt amplifiers I forgot about my Decware  EL-84 type tube SET I built. I am using it for my Kitchen 85db cheap Dayton speakers. Plenty of power and excellent sound in my not small kitchen. Rated at 2.3 watts. Not large but not tiny kitchen either. A popular amplifier offering with many happy customers by Decware. Excellent retail choice by a reputable seller at a reasonable price. Lifetime warranty. 

 

http://www.decware.com/newsite/SE84CKC.html

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Hello Tube Fanatic, (or someone else familiar with these designs)

Trying to resurrect this topic... in addition to the Little Gem, you also have the "Little Sweetie" SET.  In comparing Little Gem with Little Sweetie, what are strengths of each?  And do you have a drawing of the stereo version of Little Sweetie? ... I have drawing of the mono version.  For me to have a successful build I need to keep it simple!  

 

Pete

 

 

 

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The Gem and Sweetie sound different as the former is pentode based, and the latter is a triode strapped pentode.  There are many online articles which highlight the differences between the two. 

 

It is far simpler to build the Sweeties as individual mono amps than to put both on a single chassis due to differences in lead dress when doing them as mirror images.  I definitely recommend staying with the mono arrangement.

 

 

Maynard

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13 hours ago, Jeffrey D. Medwin said:

 If you can DIY, P.M. me, and I will offer ideas for you to consider as  a circuit re-do.

 

Thanks for the offer, but I'm not re-doing anything to the circuit. 

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On 1/31/2020 at 12:35 PM, Jeffrey D. Medwin said:

 

 

Yep, the Wright amp was terribly designed, he had no clue.  He had a terribly high DCR power supply, low fi at its worst.  Look at the DCR of the choke leading to the 2A3s, I seem to recall 254 Ohms.  It needs to be 20 Ohms or less,..... I use two chokes at 6 Ohms each.   NO dynamics in the Wright amp, plus it was a three stage amp ( high signal losses) with a stupid cathode follower driving the 2A3 grid.  OMG, that is typical for the uninitiated public. 

 

 

     415111853_AnnotatedGeoWright2A3ampEDGilfus2.thumb.JPG.4df77279de9ea594638b804ebc0b8a1d.JPG

 

EDIT Holy smokes.  Let us look at this.

 

Power supply He had 480 Ohms, perhaps divided by 2 or 240 Ohms, PLUS a 180 Ohm B+ choke, feeding the 2A3s.  You are not kidding that amp will sound anemic.  Its got 240 + 180 Ohms of added resistance, that the power transformer must power through, before ever feeding the 2A3 tube.  In 2019, we use two 6 Ohm chokes ( Hammond 159ZAs) of resistance.  Totals 12 Ohms VS:  420 Ohms !!! 

 

What do you think delivers pulsed energy on demand better to the 2A3 tube??  420 Ohms resistance or 12 Ohms resistance. ???  A 35 to 1 improvement .  His use of a P.U.ny 5Y3 needs to be changed to a 5U4GB, a much more powerful rectifier. 

 

And notice the yellow highlighted negative feedback loop ( out of time ) from the plate of the second tube, BACK to the cathode of the first triode.  Its got a 522K resistor in it. Negative feedback is bogus, un needed with a 6SN7GT triode tube. 

 

And he runs the 2A3 plate dissipation too high for long term life.  It doing 14.16 Watts of plate dissipation, and has a 15 Watt rated Maximum dissipation.   Running it so hard at 94.4% of maximum is un necessary.  No wonder Deang, you were disappointed. 

 

 

 

Couldn't disagree more. Have you listened to it? I've spent a massive amount of time listening to George Wright amplifiers and preamplifiers. I've owned just about all of his 2a3 amplifiers especially these monos and they sound superb. As they say if it measures wrong but sounds right your measuring the wrong thing.

 

 

 

 

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55 minutes ago, seti said:

 

 

 

Couldn't disagree more. Have you listened to it? I've spent a massive amount of time listening to George Wright amplifiers and preamplifiers. I've owned just about all of his 2a3 amplifiers especially these monos and they sound superb. As they say if it measures wrong but sounds right your measuring the wrong thing.

 

 

 

 


 

} Having owned a complete Wright amp/preamp kit (2a3) I agree they did sound very, very good. Enjoyed them waay more than another popular push pull KT88 amp often lauded around here. And while obviously far less power they packed quite a punch for 3.5 watts.

Did they run out of steam pushing Jubes to above average volumes, of course they did. While having absolutely zero design/circuit ability I do have ears and know how and what I hear and they sound great. I believe the audio community familiar with George’s products feel the same. I have yet and never will “listen” with a circuit diagram in front of me, I use my ears. Seems looking at drawings and graphs is popular around here and takes the place of evaluating with your senses. 

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This is my version of the Little Sweetie.  I'm a ham operator.  The output transformer is a military salvage unit which is likely very broad response, originally built for military aircraft.  Basically I had all the parts on hand,  but cost likely runs to about $30 for me.  I have all the components mounted and wil complete the wiring in the next few nights, give a full report soon on my "aural" impressions.  I decided to go with a tube rectifier so I can say there is no solid state component in it...I also replaced R10 with a true filter choke with a 200 ohm value, which is more typically how a vintage power supply would have been set up.  The tubes are quite common and inexpensive or free.  My rectifier is a 5V4 but many would serve the purpose. Put the input jack close to the 6SJ7 to keep the signal path short.  Volume control on the left, tone range center, on/off left.  The outpout transformer has taps for 4, 8 and 16 ohms so I will be able to run options out to the speaker connect terminal.  I will eventuually give an aural comparison of this thing to a Cornwall vs. my McIntosh solid state amp, at least in mono.  Since the output transformer is a unique I probably cannot build another one identically, but if this works well I may build matched mono amps.

IMG_0655.JPG

Edited by AB3CX MIke
better text
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2 hours ago, Jeffrey D. Medwin said:

 

 

I so much enjoyed seeing where you positioned the RCA input jack. 

 

I have found the quality of the RCA jack, can also effect the sonics of a component considerably.  Look into Neutric RCA jacks, available widely, and about $2.00, gold plated directly over brass, sound decent.

 

If you want to go stereo, you could sell that output XFR easily on eBay.  Then order two Softone RW-20 R-Core SE output transformers from Japan, about $120 each.   VERY low in distortion - VS the best E- I XFRS, and flexible ( 2 primary taps).  SEE their extensive published on-line specs.   Takes up to 400 hours to fully break - in.  

 

Jeffrey Medwin

I have been building cables since 1988 and have used a lot of expensive high end to ultra high end connectors and I have been using Neutric Rean connectors for a long long time now, they are sturdy durable inexpensive and best of all they sound VERY good. Hard to beat!

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On 2/5/2020 at 8:06 PM, moray james said:
On 2/5/2020 at 8:06 PM, moray james said:

I have been building cables since 1988 and have used a lot of expensive high end to ultra high end connectors and I have been using Neutric Rean connectors for a long long time now, they are sturdy durable inexpensive and best of all they sound VERY good. Hard to beat!

Hi Jeff,

         

  I think I may have bought this output transformer years ago on eBay thinking of a future project. May have paid $15 plus shipping then. Literally every part for this was on hand in the  shop.

 

           So I wired it up last night and tested it today.  Basically I ran the output of the CD player right into the phono input jack, and fed the output 8 ohm tap to an old Large Advent speaker.     Honestly it sounds great  I initially had some hum, which was eliminated when I made the connection at point B on the schematic.  Originally I did not get why it was designed that way, but following the instructions can't hurt!!  I used electrolytics 22 ufd/450 volts because that's what I had on hand,  which does not seem to hurt it at all.    As far as volume, it's plenty loud at about 25% rotation of the volume control. I happened to try a 6L6GA I had on a shelf, I think it sounds better than the 6Y6. I  am going to play around with it a little more, I could have done a neater job under the chassis. I'd recommend this to anyone to try...

Edited by AB3CX MIke

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With the 6Y6 you should have 200V plate to cathode and bias should be around -30V.  The second harmonic distortion of the 6L6 will be considerably higher which could explain why you found it more pleasing.  In any event, glad you like it!

 

 

Maynard

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I had so much fun with the Little Sweetie, I built this push pull 6L6 a few days later. The chassis was originally the amp/power supply from a Scott 510.  Construction was easy. This one really is a step up, but to get an identical looking twin I need to find another Scott 510 to cannibalize.

 

 

IMG_0672 (2).JPG

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This is the schematic to the amp pictured above.  Easily driven by a CD player alone. The cool part of the adaptation is that a Scott 510 has two rectifier tubes.  The 25Z5 was pulled, the filament voltage rectified with a diode bridge to get one bias voltage. That is in the little octal plug on the left side.  The other bias voltage was generated with a very small transformer giving 150V.  Most builders would more easily use a typical antique radio transformer to generate the plate B+, and the required filament voltage.  These big old battleship vintage radios which used two chassis have lots of room under the hoods, all the iron plus nice output transformers.  I have my eye on a Facebook Marketplace Capehart Panamuse M-FM which would yield the needed parts for my twin, but is too expensive at the moment....

IMG_0666 (2).JPG

Edited by AB3CX MIke

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Jeffrey,  your friend’s preference of his own amp over the Wright doesn’t make him right!  Apparently, some folks have praised the sound of the Wright amps:

 

http://www.audioreview.com/product/amplification/amplifiers/wright-sound/wpa-3-5-monoblocks.html

 

Are you saying that those owners didn’t  know what to listen for?

 

 

Maynard

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The comments were made at the time of ownership, not from memory.  The bottom line here, is listener satisfaction.  These folks liked what they heard!  Would they have liked your amp better?  Who knows?  It would be instructive to go back and read the goals of the nascent hifi industry to put this in its proper context.  Basically, if someone is happy with the sound they are hearing, no one will convince them that they are incorrect for doing so.  And, I must restate what I posed to you previously- if person A says the system sounds wonderful, and person B says it sounds like crap, who is correct???  
 

 

Maynard

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9 minutes ago, Jeffrey D. Medwin said:

Its a function of their experiences, over their lifetime, listening.

How come it can't be a function of how one person hears things differently than another?

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Thank you for finally conceding the point that I've been trying to make here!  So, while your suggested modifications to George Wright's amp design may have some degree of technical merit, to some listeners it will result in what they perceive as poorer sound!  The first paragraph of the following states the case better than I can:

 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3578393/

 

Time for dinner......

 

 

Maynard

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24 minutes ago, Jeffrey D. Medwin said:

 

 

Thats fine with me, Maynard.  I would't modify the Wright 2A3.   I'd just dump it on someone whop would be pleased to have it.


Too bad Mr. Wright isn’t here to defend his design/circuit for better or worse. But alas, he passed several years ago — 

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