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 Post subject: Re: Another Little Prince- tube preamp
PostPosted: Jun Mon 03, 2019 6:59 pm 
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OK Flip. I am getting 26.5v and B+ is 278v.
Is that voltage an ok elevation?
If this doesn't work, I will look for a different power transformer.

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 Post subject: Re: Another Little Prince- tube preamp
PostPosted: Jun Mon 03, 2019 7:04 pm 
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Flip, if you can remember a while back we worked out a circuit using a cap dropper from 120v to 12v.
It was very simple but I forgot the values.
I actually need 9v at about 100ma. It is for the remote volume control box.
Thanks.....

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 Post subject: Re: Another Little Prince- tube preamp
PostPosted: Jun Tue 04, 2019 2:03 am 
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Well, believe it or not, that fixed it. Yup. Now totally noise free.
When I powered back up, I was waiting for the hum. No hum, wait, the hum was in the phono input controlled by volume.
Flipped to phono, just a whisper of a hum. Played a record. Beautiful fidelity. Yet just a little hum. But wait, the hum pot.
Adjusting the hum pot fixed it. No hum at all.
Thanks Flip
That most logical solution was so illogical.

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 Post subject: Re: Another Little Prince- tube preamp
PostPosted: Jun Tue 04, 2019 4:42 am 
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Joined: Nov Sat 26, 2011 4:09 am
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john8750 wrote:
Well, believe it or not, that fixed it. Yup. Now totally noise free.
When I powered back up, I was waiting for the hum. No hum, wait, the hum was in the phono input controlled by volume.
Flipped to phono, just a whisper of a hum. Played a record. Beautiful fidelity. Yet just a little hum. But wait, the hum pot.
Adjusting the hum pot fixed it. No hum at all.
Thanks Flip
That most logical solution was so illogical.
Hot diggity dog. That's great news.

I wish I could take credit for it but I was just borrowing an idea done long ago.

I'd never personally used that trick before, opting instead for the common practice nowadays of just powering the heaters off DC, but it's nice to know "the old fashioned way" still works. :wink:

I'm curious, where in the pot's travel did it null?


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 Post subject: Re: Another Little Prince- tube preamp
PostPosted: Jun Tue 04, 2019 5:30 am 
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Joined: Dec Mon 29, 2014 9:39 pm
Posts: 5159
Location: Los Angeles
Flipperhome wrote:
john8750 wrote:
Well, believe it or not, that fixed it. Yup. Now totally noise free.
When I powered back up, I was waiting for the hum. No hum, wait, the hum was in the phono input controlled by volume.
Flipped to phono, just a whisper of a hum. Played a record. Beautiful fidelity. Yet just a little hum. But wait, the hum pot.
Adjusting the hum pot fixed it. No hum at all.
Thanks Flip
That most logical solution was so illogical.
Hot diggity dog. That's great news.

I wish I could take credit for it but I was just borrowing an idea done long ago.

I'd never personally used that trick before, opting instead for the common practice nowadays of just powering the heaters off DC, but it's nice to know "the old fashioned way" still works. :wink:

I'm curious, where in the pot's travel did it null?





The pot is about 30/70. But the dwell is wide, at least 5%
It sure is a good trick.

I mean the amp is just remarkable and so is the 807 Williamson/Flip.
The treble now responds to the pot movement. before, it did not.
It is for sure hi-fi.

I left the gain pot in the circuit in the 807 amp. It is set at about 80%. Don't want to get into any possible high end distortion.
But have plenty of volume.
And the MP3 boost is just perfect.

You should build this amp Flip. I have many leftover parts, yours if you want them.
I will even bend you a chassis.

Thanks Flip 8) Not a bad guy, for a Vulcan :lol:

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John Smith, over and out.
If I did something right, I made a mistake.


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 Post subject: Re: Another Little Prince- tube preamp
PostPosted: Jun Thu 06, 2019 9:26 pm 
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Joined: Nov Sat 26, 2011 4:09 am
Posts: 9517
Location: Texas. USA
john8750 wrote:
Flipperhome wrote:
john8750 wrote:
Well, believe it or not, that fixed it. Yup. Now totally noise free.
When I powered back up, I was waiting for the hum. No hum, wait, the hum was in the phono input controlled by volume.
Flipped to phono, just a whisper of a hum. Played a record. Beautiful fidelity. Yet just a little hum. But wait, the hum pot.
Adjusting the hum pot fixed it. No hum at all.
Thanks Flip
That most logical solution was so illogical.
Hot diggity dog. That's great news.

I wish I could take credit for it but I was just borrowing an idea done long ago.

I'd never personally used that trick before, opting instead for the common practice nowadays of just powering the heaters off DC, but it's nice to know "the old fashioned way" still works. :wink:

I'm curious, where in the pot's travel did it null?





The pot is about 30/70. But the dwell is wide, at least 5%
It sure is a good trick.

I mean the amp is just remarkable and so is the 807 Williamson/Flip.
The treble now responds to the pot movement. before, it did not.
It is for sure hi-fi.

I left the gain pot in the circuit in the 807 amp. It is set at about 80%. Don't want to get into any possible high end distortion.
But have plenty of volume.
And the MP3 boost is just perfect.

You should build this amp Flip. I have many leftover parts, yours if you want them.
I will even bend you a chassis.

Thanks Flip 8) Not a bad guy, for a Vulcan :lol:
Do you think this version is better than the 20EZ7 one or the same?

Yeah, I'd like to build it and the power amp too. I forget off hand, what power transformer did you use for the preamp?


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 Post subject: Re: Another Little Prince- tube preamp
PostPosted: Jun Thu 06, 2019 11:56 pm 
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Joined: Dec Mon 29, 2014 9:39 pm
Posts: 5159
Location: Los Angeles
Don't know witch one is better. I can assure you that both is well into the hi-fi zone 8)
I am totally amazed and so proud to display them to my friends. :lol:

The preamp power transformer is Edcor-XPWR218 $50.91
Will ship you the chassis and many leftover parts.

Here is the finish photo. See the remote volume control on the second shelf. Works fine. Gets 9vac power from the 12v filament power in the Little Prince through a 33ohm resistor.
I need to label the controls yet.
And see the 807 on the bottom. That's not a knot hole on the side wall, must be one of those spirit orbs. :roll:
Attachment:
lpfinal3.jpg
lpfinal3.jpg [ 231.1 KiB | Viewed 105 times ]

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If I did something right, I made a mistake.


Last edited by john8750 on Jun Fri 07, 2019 12:04 am, edited 1 time in total.

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 Post subject: Re: Another Little Prince- tube preamp
PostPosted: Jun Fri 07, 2019 12:03 am 
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Joined: Dec Mon 29, 2014 9:39 pm
Posts: 5159
Location: Los Angeles
BTW
I built that cabinet from an old WW2 ammo case. It was made with some very fine pine. It held 12 large shells. Of course the shell were missing.
Was painted a very old and wiped out OD. I kept the green but lightened it up a bit.
Lots of fun.

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John Smith, over and out.
If I did something right, I made a mistake.


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