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Little Sweetie Forum amplifier project


henry4841

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1 hour ago, Area 51 said:

 

And, not particular to Sweetie but regarding tubes in general; Where can I find some sort of guide to tell me what tubes are acceptable replacements for tube "rolling" or experimenting in search of different sounds or tones or flavors or ... whatever you call it? How do you know what's interchangeable and what is not?

 

 

I just do a search and use tube equivalent.

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14 minutes ago, Area 51 said:

Can do for Sweetie, thanks - I like the long life and affordability aspects but I was asking a more general question about tubes in general.

 

 If the tubes provided were new they will likely need some break in time at least 100 hours 

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49 minutes ago, jjptkd said:

 

 If the tubes provided were new they will likely need some break in time at least 100 hours 

That is what is said on the net. Sound good to me when brand new but most what you read on net say best after 100 hours on them. In a tube there are some impurities in the materials inside that have burn off and be caught by the getter.  

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If any of ya'll think you may want to make electronics a hobby should take a good look at the scope and signal generator I just bought. For less than $200 you will have as good equipment of some the electronic repairmen I watch on youtube. I am talking guys that do repairs for a living, not for play. What you find on their bench will often by a 30 year old 20mgz scope and signal generator. These were not hobbyist items but for the working man. They are old and there is always a chance that the school they came from were not honorable and throwed in a non working one when they were sold as all working in bulk. The seller seems to be straight and if you get good ones chances are they will last a long time. A friend I helped online get into the hobby of building amplifiers bought a new scope and signal generator and he really knows very, very little about electronics. The reason being his kids think he's is a genius now. For $200 they will make some of your in-laws believe you are smart.  

 

https://www.ebay.com/itm/265864241373?hash=item3de6be60dd:g:2LwAAOSwlOpi~865

https://www.ebay.com/itm/265862712323?hash=item3de6a70c03:g:rmYAAOSwUU1i~8x~

 

Just to add I bet the seller will sell them for $70 each buy it now if you contact him. I know, unless things have changed. 

 

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To do any tube swapping with the Sweetie you are going to have to find another tube that will be operated at the same voltage and current rating as the tube you are going to replace it with. Right off the top of my head I do not know any other tubes to substitute for the ones in the Sweetie. There are likely some pre-tubes that could be used but the ones that Area51 has in his amp have engraved on them "Made in England." I would almost bet money they are Mullard tubes and if they had the Mullard name on them they would be $100 apiece or more. In other words a highly respected brand of tube. Believe me there was a strong temptation for me to keep those tubes but I bought them for Area51 one's amp and that is where they went. 

 

You can get away with trying different types of tubes in an EL34 amplifier. My SET EL34 amplifier was designed for the EL34 tube. Other tubes such as the 6L6, KT-77,KT-88 and others that belong to the family of the EL-34 can be swapped in without doing any harm to experiment some, but. The but is my EL-34 is optimized for the EL-34 tube and any other family  of the EL-34 will work but the amp is optimized for the EL-34. Voltage and cathode resistor changes need to be made for it to be optimized for any of the other tubes in the family of EL-34 tubes. That is if you want to get the best out of a specific tube. That being said with that amplifier it can be done and it is fun swapping the many different offerings of the EL-34 family of tubes in it. Personally I like the sound of the 6L6 tube. Maynard has said to me in the past that it is not his favorite tube. The 6L6 has a sound much like the 6Y6 to me in tone, probably the reason I like that sound. 

 

By the way the 6L6 tubes I have are not exactly 6L6's but a Russian version of it called the 6N3C. This is an old audio Russian tube and not one of the new production ones being sold by JJ or Sovtek etc. Use to buy them cheap but have not priced them lately. Big and sound good to me. By the way some consider bigger is better when it comes to tubes. If you notice bigger tubes are bigger priced. A few nights ago I was doing some swapping of tubes in the SET EL-34 of mine. Three different types. The Gold Lion KT-77's sound really good. The 6N3C's sound somewhat better to my ears. A pair of JJ EL-34's not so much to my liking. Sound good mind you but a little touch of harshness to my ears in the vocals. Probably just me. 

 

Last night I did a little comparison of one of Nelson's FW clones with the Sweetie. The Aleph J. Great sounding SS single ended amplifier. Sounds much like a SET tube amplifier. The guy can sure design a SS amplifier that has a very tube like sound. I really like the sound of the Aleph J. That being said I will give the edge to the Sweetie when it comes to vocals. Slight edge mind you, the Aleph sounds really good. The main difference is the price of a new First Watt amplifier vs a well built SET amplifier. Use to be a FW amplifier was in the neighborhood of $4000 to $5000 range. That was when Nelson was personally building the First Watt amplifiers himself. He has since given the production of the First Watt brand to his other company to build, Pass Labs. I have noticed the newer offerings price of First Watt amplifiers has went down some. The newer offerings that is. Cheaper labor it seems than the master himself building. You can find a well built SET amplifier for around 1/2 the price of one of Nelson's SS amplifiers. Better bang for buck is the way I see it. I am like many others in that when it comes to sound tubes still rule. 

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14 hours ago, tube fanatic said:


I don’t have the schematic handy, but it should be the driver screen bypass cap.  Like the cathode bypass cap, it is used to put the screen at ground potential for the AC signal voltages.  That is the simple explanation.  
 

Maynard

Sorry Maynard, I should have been more specific. The C3 cap is on the 6SJ7 pentode number 2 grid, screen grid that goes to ground. You are correct in knowing what I was asking.

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Hey guys we had an increase of 2K views yesterday. Hard to believe there has been so much interest in hearing what two old guys like Maynard and myself have to say about tubes. Maynard is actually the tube guy. I did not have a tube in my house until 10 years ago. SS had always been my interest in electronics since my youth whereas Maynard's focus has been tubes in his. I hope Klipsch let's us continue. At least until they come out with a tube amplifier of their own. Nothing ever stays the same, there is always change at every corner in life. 

 

Planning on doing a little work on the new Sweetie project this morning. I am still waiting for some parts for it from Parts Express. Shipping cost has really increased. I bought $30 worth of parts and shipping was $10, 1/4 of the money I spent there. Nothing we can do about it but complain. 

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3 hours ago, henry4841 said:

To do any tube swapping with the Sweetie you are going to have to find another tube that will be operated at the same voltage and current rating as the tube you are going to replace it with. Right off the top of my head I do not know any other tubes to substitute for the ones in the Sweetie. There are likely some pre-tubes that could be used but the ones that Area51 has in his amp have engraved on them "Made in England." I would almost bet money they are Mullard tubes and if they had the Mullard name on them they would be $100 apiece or more. In other words a highly respected brand of tube. Believe me there was a strong temptation for me to keep those tubes but I bought them for Area51 one's amp and that is where they went. 

 

You can get away with trying different types of tubes in an EL34 amplifier. My SET EL34 amplifier was designed for the EL34 tube. Other tubes such as the 6L6, KT-77,KT-88 and others that belong to the family of the EL-34 can be swapped in without doing any harm to experiment some, but. The but is my EL-34 is optimized for the EL-34 tube and any other family  of the EL-34 will work but the amp is optimized for the EL-34. Voltage and cathode resistor changes need to be made for it to be optimized for any of the other tubes in the family of EL-34 tubes. That is if you want to get the best out of a specific tube. That being said with that amplifier it can be done and it is fun swapping the many different offerings of the EL-34 family of tubes in it. Personally I like the sound of the 6L6 tube. Maynard has said to me in the past that it is not his favorite tube. The 6L6 has a sound much like the 6Y6 to me in tone, probably the reason I like that sound. 

 

By the way the 6L6 tubes I have are not exactly 6L6's but a Russian version of it called the 6N3C. This is an old audio Russian tube and not one of the new production ones being sold by JJ or Sovtek etc. Use to buy them cheap but have not priced them lately. Big and sound good to me. By the way some consider bigger is better when it comes to tubes. If you notice bigger tubes are bigger priced. A few nights ago I was doing some swapping of tubes in the SET EL-34 of mine. Three different types. The Gold Lion KT-77's sound really good. The 6N3C's sound somewhat better to my ears. A pair of JJ EL-34's not so much to my liking. Sound good mind you but a little touch of harshness to my ears in the vocals. Probably just me. 

 

Last night I did a little comparison of one of Nelson's FW clones with the Sweetie. The Aleph J. Great sounding SS single ended amplifier. Sounds much like a SET tube amplifier. The guy can sure design a SS amplifier that has a very tube like sound. I really like the sound of the Aleph J. That being said I will give the edge to the Sweetie when it comes to vocals. Slight edge mind you, the Aleph sounds really good. The main difference is the price of a new First Watt amplifier vs a well built SET amplifier. Use to be a FW amplifier was in the neighborhood of $4000 to $5000 range. That was when Nelson was personally building the First Watt amplifiers himself. He has since given the production of the First Watt brand to his other company to build, Pass Labs. I have noticed the newer offerings price of First Watt amplifiers has went down some. The newer offerings that is. Cheaper labor it seems than the master himself building. You can find a well built SET amplifier for around 1/2 the price of one of Nelson's SS amplifiers. Better bang for buck is the way I see it. I am like many others in that when it comes to sound tubes still rule. 

 

It would be interesting to know that actual tubes the Russians did invent versus cloning western tubes. I'm sure I could Google it, just haven't. 

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Some questions have come up about R1/C1 at the input to the Sweetie.  I termed it the “ear bleed filter” after hearing complaints from a guy that many modern recordings contain so much high frequency boost that they make his ears “bleed!”  
 

The components form an adjustable low pass filter which allows the high frequencies to be attenuated to suit listening preferences.  It is quite useful and is standard in all of my builds.  I initially included a bypass switch which allowed its total removal from the circuit, but no one used that feature so the switch was eliminated.

 

Eventually, I may have to head south so Henry and I can sit on the porch in rockers as he suggested.  For now, on the very rare occasions that my wife gets me to stop working and relax, I sit at the old unused railroad station with other old farts and watch the freight trains go by………

 

Maynard

 


 


 

 

BABD9BF5-43CF-4AA1-BC43-1F5D245D012E.jpeg

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3 hours ago, tube fanatic said:

 

Eventually, I may have to head south so Henry and I can sit on the porch in rockers as he suggested.  For now, on the very rare occasions that my wife gets me to stop working and relax, I sit at the old unused railroad station with other old farts and watch the freight trains go by………

 

Maynard

 


 


 

 

BABD9BF5-43CF-4AA1-BC43-1F5D245D012E.jpeg

Can't think of a better way for us to pass the time at this stage of our life. 

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1 minute ago, Area 51 said:

 

I am grateful to Henry for building Sweetie. And I am grateful to you, Maynard, for designing Sweetie.

 

Whatever our age, you guys ROCK !

The best compliment ever from you about the Little Sweetie. I hope you enjoy it for many years to come. As many amps as I have now I would not want to be without one Sweetie in my collection. 

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9 hours ago, henry4841 said:

By the way the 6L6 tubes I have are not exactly 6L6's but a Russian version of it called the 6N3C. This is an old audio Russian tube and not one of the new production ones being sold by JJ or Sovtek etc. Use to buy them cheap but have not priced them lately. Big and sound good to me. By the way some consider bigger is better when it comes to tubes. If you notice bigger tubes are bigger priced. A few nights ago I was doing some swapping of tubes in the SET EL-34 of mine. Three different types. The Gold Lion KT-77's sound really good. The 6N3C's sound somewhat better to my ears. A pair of JJ EL-34's not so much to my liking. Sound good mind you but a little touch of harshness to my ears in the vocals. Probably just me. 

I decided to check Ebay for the price of the 6N3C tube now and as I thought they are not cheap anymore. I have a number of them in my box of tubes that I bought years ago for practically nothing considering the price of tubes. The word must have got out how good they sound increasing the price. As previously stated they are Russian NOS tubes, made in Russia when tubes ruled. Probably still a good deal at todays prices. A quick check of a NOS American made 6L6 reveals you can purchase a 6L6GA for $40 at Tube Depot. Most of time the GA or other similar designation on the end of a tube number is the physical way it looks. We knock gear made in Russia now but one must remember Russia sent a missile into space before we did. Like a lot of stuff they did they got the info on how to do it from the west in secret. Not such a deal to purchase now but still it is a good sounding tube to my ears. 

 

https://www.ebay.com/itm/394201461586?hash=item5bc83cf352:g:LQwAAOSwMMJiLTFs&amdata=enc%3AAQAHAAAAkJDdHlxi0LM1I4mD8PofUazIwR9NVnUvq2aTDQM4oKq7%2FU8U2FPkCDSqETqUPfTdANMCXLfi4Sr2MEUdMTF1yhGIPtifhkiA87OqIuPyUQuCWDn%2BT8ofLsskyZSKUCzqtdKsiCOOmzhFHJejTJQEkm62GnC3pMlpJkUqARRTGWD6d4NblCSnX%2FqoVRfCsOEzHA%3D%3D|tkp%3ABk9SR9C0r8TiYA

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