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The "Ultimate Gem" SEP is here!


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Maynard,  Good chance I will have some questions for you.  I will be building in spare time on saturdays so it will be a number of months at least before complete.  I also will be ordering xformers from Edcor which, I understand, could take 6 weeks.   

 

I do not have high efficiency, Klipsch speakers. I do have a number of speakers I can use... some "transmission Line" speakers that are 90.5 db efficient and other less efficient, single-driver speakers I would use with a powered sub.  I am curious to see how these will do with the 1.7 watt Ultimate Gem.    

 If needed, I may need to build more speakers. :D) 

 

Pete

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  • 3 months later...

Sir Maynard,  in the Ultimate Gem power supply,  what is the benefit of the “Manual soft-start” feature?  I am leaning towards omitting this switch and resistor for the sake of simplification... I gather it is not critical? 

 

Thank You,

Pete

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Sir?  I work for a living so the title is not suitable!  Yes, you can eliminate the soft start. Its function is to reduce the initial surge to the driver filament, but in actuality it won’t make all that much difference with tube longevity.  
 

 

Maynard

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Jeff, I appreciate your input regarding speaker efficiency vs amp wattage.  I should be be finished with Maynard’s Ultimate Gem amp within the next few weeks and am anxious to hear how the combination of this amp and my speakers perform.  ... Near-field listening might be the only option.  Speaking of higher wattage amps,  Maynard’s 6aQ5 based amp has also caught my attention for a possible future build but first I need to see if I followed Maynard’s Ultimate Gem drawing well enough so, when powered up, it outputs music, not smoke. My fingers will be crossed.  

Pete

 

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Maynard,  This evening I finished the power supply enough to power it up.  I am measuring 171vdc output.  Before I plug into the Ultimate Gem amp,  is this voltage in the ballpark of what it should be?  I still need to install the output transformers but I am very close to at least thinking this amp is complete.

 

Pete

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7 hours ago, Pdlu said:

Maynard,  This evening I finished the power supply enough to power it up.  I am measuring 171vdc output.  Before I plug into the Ultimate Gem amp,  is this voltage in the ballpark of what it should be?  I still need to install the output transformers but I am very close to at least thinking this amp is complete.

 

Pete


 

The voltage is perfect and will drop to the upper 150s when loaded by the amp.  Verify that the bleeder is functioning in the power supply by noting a slow and steady drop after power is removed.  When connected to the amp, the tube filaments will discharge the caps very rapidly.

 

 

Maynard

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Success... another Ultimate Gem is playing tunes!  Thanks again, Maynard, for sharing your hard-earned knowledge and expertise, creating this design.  I can see that the biggest weakness I have going on with my new low-wattage system is my 90.5 dB desktop speakers.  Set to max output, these 4fe35, faital, 4 inch single drivers speakers are loud enough for some good, relaxing listening but I won’t be rockin’ The house. (Maynard’s and Jeff’s earlier comments on speaker efficiency were spot-on).   These faital drivers only have a few hours break-in and they have a reputation for being light on bass and sometimes “shrill” on the top.  Playing music with piano instrumentals, some of the notes are definitely overly shrill.  Playing other music, the U Gem is VERY nicely detailed.  I can hope, with some more break-in, these speakers will improve somewhat.  I still need to try some of my other speakers with the U Gem, but my other speakers are even less efficient. 

 

 As has been said the U Gem has very little background noise. With volume at max and ear up to the speaker I hear zero hum.

 

Silly me, when I ordered tubes for the U Gem I didn’t order extras for rollin’... I only have the three GE tubes.

 

that’s all for now... I have more ‘sperimenting and listening to do.

 

Pete

 

FCDF1F83-31B1-4386-B99F-7AC21AE9E4E8.jpeg

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Maynard, As you can see in the attached pic, l tried to follow the layout in your photo however, because I didn’t place tubes close enough and also because I ordered components with different construction than what you used I needed to add wire length to a number of resistors and caps.  I had to deviate a lot from your design to get those large “high frequency” pots to fit where you used those small blue pots.  

C4870483-FD66-4364-85DC-FDAE4E046171.jpeg

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