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Little Sweetie Forum amplifier project


henry4841
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16 minutes ago, henry4841 said:

Just some rambling thoughts this morning. If we put our heads together I bet we could design an amplifier around the EL84 tube as good if not better than the Decware Zen. His design is nothing unique or special. I would like to see it built with one of those Antek Toroidal transformers. Cheaper and shielded. We would have to have a design without using a center tap transformer. Also SS rectifier power supply. We could call it "Forum EL84 Amplifier". Be something to do and I would more than likely build it. Lets keep the cost down much like the Sweetie and not complicate it too much. Team effort will produce a fine sounding little amplifier. 

I know for a fact that an amp can be designed as good or better than the Zen and less expensive. In triode mode, the EL84 and 6V6 are similar. You could also use a 6BQ5, but those are probably more expensive than your pedestrian 6V6. 

 

Decware has very creative marketing which has worked well for them. If I were in business making electronic products, I would be doing the same thing. 

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36 minutes ago, henry4841 said:

Just some rambling thoughts this morning. If we put our heads together I bet we could design an amplifier around the EL84 tube as good if not better than the Decware Zen.

 

If you don't mind push-pull and PC boards, the PC board used by Audio Note https://ankaudiokits.com/product-category/el84-amps/ and tubes4hifi http://www.tubes4hifi.com/ST35.htm is available as a bare board https://www.aliexpress.com/item/3256801585807617.html.

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22 minutes ago, Edgar said:

 

If you don't mind push-pull and PC boards, the PC board used by Audio Note https://ankaudiokits.com/product-category/el84-amps/ and tubes4hifi http://www.tubes4hifi.com/ST35.htm is available as a bare board https://www.aliexpress.com/item/3256801585807617.html.

I just finished collecting parts to build an ST-35 clone. Edcor transformers, PC board, EL84, 12AX7, 12AU7 tubes, parts from Mouser and Digikey. I'm pushing $1K without a chassis yet. So much for budget build! The days of cobbling stuff together like my grandpa did, are over!

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13 minutes ago, capo72 said:

I just finished collecting parts to build an ST-35 clone. Edcor transformers, PC board, EL84, 12AX7, 12AU7 tubes, parts from Mouser and Digikey. I'm pushing $1K without a chassis yet. So much for budget build! The days of cobbling stuff together like my grandpa did, are over!

Expenses for a PP ST-35 build does add up. But look what you will have when finished. Poor mans McIntosh is what they use to say back in the day. 

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If we work together and do design a SET EL84 amplifier I will give considerable thought to building it. But it is not going to be like the last build where cost was a big consideration. I want to get a pair of those NOS RCA EL84 tubes at $120 apiece and build a pretty wood case much like this one. That and stick the Hammond OPT's underneath where they cannot be seen. They sound really good but not the best looking OPT's as far as appearance. They are built and sold to be hid. I would want to use Nichicon 105C caps and Dale resistors. In other words building like I would for myself using what little knowledge I have learned the last 10 years building tube amplifiers. I would like to sell it after building the reason being there is no way I need another tube amplifier. Last count of tube and SS amplifiers I have now was like 22 or 24. It will not be a labor rate of $10 an hour either but more in line for what it's worth. In other words a premium hand built amplifier. If there are no buyers that will be fine. It is being hard for me to sell this Sweetie after I have finished it. Like one of your kids leaving for college. Never done it before, selling an amp I have built. But the plan is to pack it up and send it on it's way first of next week. 

P1030824.JPG

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1 hour ago, Edgar said:

 

If you don't mind push-pull and PC boards, the PC board used by Audio Note https://ankaudiokits.com/product-category/el84-amps/ and tubes4hifi http://www.tubes4hifi.com/ST35.htm is available as a bare board https://www.aliexpress.com/item/3256801585807617.html.

It is a thought but the only time I tried building a tube amplifier on a board was not successful. I was using expensive, for me, 300B tubes and was afraid of trying to fix it damaging those tubes. Point to Point is more fun for me as well. More of a challenge. That is all that matters to me, to have fun. Something constructive for an old man to do to pass the time. 

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1 hour ago, capo72 said:

I just finished collecting parts to build an ST-35 clone. Edcor transformers, PC board, EL84, 12AX7, 12AU7 tubes, parts from Mouser and Digikey. I'm pushing $1K without a chassis yet. So much for budget build! The days of cobbling stuff together like my grandpa did, are over!

Yep. Even parts for a mid-quality 300B build will run $1k and that is with a Hammond chassis w/ wood side panels. But, considering the alternative, DIY is much less expensive than buying a completed unit. 

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44 minutes ago, henry4841 said:

If we work together and do design a SET EL84 amplifier I will give considerable thought to building it. But it is not going to be like the last build where cost was a big consideration. I want to get a pair of those NOS RCA EL84 tubes at $120 apiece and build a pretty wood case much like this one. That and stick the Hammond OPT's underneath where they cannot be seen. They sound really good but not the best looking OPT's as far as appearance. They are built and sold to be hid. I would want to use Nichicon 105C caps and Dale resistors. In other words building like I would for myself using what little knowledge I have learned the last 10 years building tube amplifiers. I would like to sell it after building the reason being there is no way I need another tube amplifier. Last count of tube and SS amplifiers I have now was like 22 or 24. It will not be a labor rate of $10 an hour either but more in line for what it's worth. In other words a premium hand built amplifier. If there are no buyers that will be fine. It is being hard for me to sell this Sweetie after I have finished it. Like one of your kids leaving for college. Never done it before, selling an amp I have built. But the plan is to pack it up and send it on it's way first of next week. 

When Pentodes or Tetrodes are wired in triode mode, there is less of a sonic signature in my opinion. Not a bad thing, but just making an observation. You could use JJ EL84 or NOS EL84's and probably not notice much difference. 

 

Except for the JJ5AR4, I've had good luck with a lot of their tubes and the price is nominal. 

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7 minutes ago, tube fanatic said:

For those who like the 6BQ5 or EL84 go with a 6GK6 which can be purchased NOS for about $8.  It is electrically identical but with a different pinout and was used in many tvs.  You can even go with a 16GK6 for about $3!

 

Maynard

Good idea from my teacher of tube circuits. Too much to ask for a circuit with the 6GK6?

 

https://www.diyaudio.com/community/threads/6gk6-great-tubes.312301/

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34 minutes ago, henry4841 said:

Good idea from my teacher of tube circuits. Too much to ask for a circuit with the 6GK6?

 

https://www.diyaudio.com/community/threads/6gk6-great-tubes.312301/

We could redesign the Little Sweetie to match the power output of the Zen. A new name could be BAMF. I'm not into eastern religions nor western religions for that matter. 

 

I'm sure everyone can figure out my acronym. 

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As a matter of history, if my memory serves me correctly, back when the original Zen amp came out, I believe it was Nelson Pass who coined the term unofficially. Around exactly the same time, Deckert used the name and I remember Nelson mentioning in a forum post how someone "used" that name too and he was a bit upset about it, but let it go. 

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14 minutes ago, Curious_George said:

As a matter of history, if my memory serves me correctly, back when the original Zen amp came out, I believe it was Nelson Pass who coined the term unofficially. Around exactly the same time, Deckert used the name and I remember Nelson mentioning in a forum post how someone "used" that name too and he was a bit upset about it, but let it go. 

 

Good memory.  Nelson was the first that I recall using that name.  In fact, here's the issue that I have about it:

 

IMG_2751.png.537f71b47dbeb15f52f25f6d47d1cc0a.png IMG_2752.png.c283360922f08b5e0be7db9d46a8c780.png

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I think the biggest challenge is finding a SE output transformer that has good bandwidth (and other specs) for a DIY project that are reasonable priced. Sure, they are out there, but prices are super high. James Audio Transformers were the best kept secret. Very similar to Tango and Hashimoto transformers. Supposedly, they share the same DNA if you will. 

 

If we could find a company (maybe Matt @ musical power supplies) to make a line of nice transformers with Hi-B core material, decent inductance and wide frequency repsonse, similar to what James was offering in there JS-6112HS or JS-6113HS we would be in business with some serious DIY amp builds. 

 

I have a set of James JS-6112HS and they are easily my favorite transformers in the 10 watt range. 

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