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 Post subject: Re: Philco amp re-build.
PostPosted: Aug Thu 31, 2017 9:59 pm 
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john8750 wrote:
No 60hz hum at any level. A bit of IM distortion with no input. Some at different volume levels.

Hi John:
With no input you might want to short the input leads together to avoid picking up noise.

IM distortion????

Are you sure you know what Inter-modulation distortion really is?

You would need to have at least two separate input frequencies that are interacting/mixing to get a third (harmonic) for IM "distortion".
So if you have no input.. you cannot possibly have ANY IM since you don't have any signals to interact together


"IMD results when two or more signals of different frequencies are mixed together and additional signals are formed at frequencies that are not, in general, at harmonic frequencies (integer multiples) of either source signal"


Please go here and read this:
http://www.digitizationguidelines.gov/t ... rtionaudio

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Last edited by Pbpix on Sep Fri 01, 2017 3:29 am, edited 1 time in total.

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Fri 01, 2017 1:51 am 
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Looking at the schematic the treble control should work as it is supposed to, but the bass control given it's connected to the volume control tap may not be very responsive as the volume control is turned CW past the tap.

What I don't know is if the tone controls are the boost/cut type or just cut.

I'll finish the schematic tomorrow without the tone controls then I'll make a separate one with the tone controls.

I could even make one with the Motorola tone controls if so desired. With the bass channel there would otherwise be no control over the bass aside from a level control if only the Philco tone controls are used. Would require dual gang controls, but Mark Oppat should have or be able to make what you need if you cannot find the proper controls.

When I finish the schematic Either I or you can run it by the forum members to see if there's anything wrong with it or if there's things that aren't needed.

Now if you do desire to keep the Philco tone controls I can add a bass control to the bass channel if so desired.


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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Fri 01, 2017 5:33 am 
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Pbpix wrote:
john8750 wrote:
Starting my resistor storing system. Same as you suggested Peter.
http://www.ebay.com/itm/UNIVERSAL-Kraft ... Sw3YNXaj6X

Those are a bit too small.
I use either the 3-1/2 x 6-1/2
or 3-3/8 x 6

https://www.ebay.com/sch/i.html?_from=R ... 2&_sacat=0

https://www.ebay.com/sch/i.html?_odkw=c ... 2&_sacat=0



Ok peter.
http://www.ebay.com/itm/UNIVERSAL-Kraft ... 1438.l2649

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Fri 01, 2017 5:54 am 
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john8750 wrote:

Now all you'll need is a very sturdy flat cardboard box (trayilike) to store all your resistor packets.
All those with a value with a leading "1" first and then those with a leading 2 and so on.

I arrange mine in two rows with a cardboard separator in the middle.
The left side goes from 1 ohm and up to about the 3 s.
The second row starts around the 3s and goes to the 9s.
Image

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Fri 01, 2017 6:28 am 
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Tube Radio wrote:
So the tone controls of the philco have to be there for the feedback circuit or is it just something you want?

Concerning the tone controls not doing much it is because of a lower source impedance



I just want the amps to stay original. Am sure the sound will improve when I put in the proper 6au6, and have the speakers in a box. Wont be long till the other amp is completed and I have some good test speakers.

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Fri 01, 2017 6:30 am 
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Pbpix wrote:
john8750 wrote:

Now all you'll need is a very sturdy flat cardboard box (trayilike) to store all your resistor packets.
All those with a value with a leading "1" first and then those with a leading 2 and so on.

I arrange mine in two rows with a cardboard separator in the middle.
The left side goes from 1 ohm and up to about the 3 s.
The second row starts around the 3s and goes to the 9s.
Image



That's just how I will do it. I like it.

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Fri 01, 2017 6:39 am 
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Here is my Zenith 6X9 speakers. Full range
Attachment:
zenithspeaker fr.jpg
zenithspeaker fr.jpg [ 130.78 KiB | Viewed 2966 times ]

Attachment:
zenithspeaker back.jpg
zenithspeaker back.jpg [ 115.76 KiB | Viewed 2966 times ]

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Fri 01, 2017 12:01 pm 
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john8750 wrote:
I just want the amps to stay original.



Ok I'll incorporate the tone controls in the schematic.


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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Fri 01, 2017 7:49 pm 
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I now have the 6AU6's, so after a little speaker work, I can go on with testing.
Peter said to short the input when no signal is applied. I guess that a signal will always be there
when amps are powered, so no problem.

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Thu 07, 2017 7:22 pm 
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I will install the replacement power transformer for chassis #2 today. I broke off pin 4 of the 6X4, replacement will be here by Monday. Then, testing can be done.
I am working on some test speaker boxes for the old Zenith speakers. They are to be used in my shop and are certainly not hi-fi.

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Fri 08, 2017 3:53 am 
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john8750 wrote:
Pbpix wrote:
john8750 wrote:

Now all you'll need is a very sturdy flat cardboard box (trayilike) to store all your resistor packets.
All those with a value with a leading "1" first and then those with a leading 2 and so on.

I arrange mine in two rows with a cardboard separator in the middle.
The left side goes from 1 ohm and up to about the 3 s.
The second row starts around the 3s and goes to the 9s.
Image



That's just how I will do it. I like it.


Got my resistor warehouse looking just like that. But marked only the ohm values in the top right corner.

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Sat 09, 2017 9:54 am 
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john8750 wrote:

Got my resistor warehouse looking just like that. But marked only the ohm values in the top right corner.

Great John:

I find that it helps me a bit more to put the 3 or 4 color numbers on there too... cause I like to double check when I put them back in the envelope or taking them out it helps... you'll see.
Esp these 4 colors 1% resistors... the Chinese colors against that blue is hard for me to remember.

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Sat 09, 2017 10:00 am 
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Pbpix wrote:
john8750 wrote:

Got my resistor warehouse looking just like that. But marked only the ohm values in the top right corner.

Great John:

I find that it helps me a bit more to put the 3 or 4 color numbers on there too... cause I like to double check when I put them back in the envelope or taking them out it helps... you'll see.
Esp these 4 colors 1% resistors... the Chinese colors against that blue is hard for me to remember.



I have a cool little unit I got from ebay. It is a kit for cheap, but works pretty good. It will check and identify resistore, caps, inductors, and transistors, and diodes. works on a 9 volt supply and has a digital readout. I check every component before installation.

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Sat 09, 2017 10:31 pm 
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john8750 wrote:
Pbpix wrote:
john8750 wrote:

Got my resistor warehouse looking just like that. But marked only the ohm values in the top right corner.

Great John:

I find that it helps me a bit more to put the 3 or 4 color numbers on there too... cause I like to double check when I put them back in the envelope or taking them out it helps... you'll see.
Esp these 4 colors 1% resistors... the Chinese colors against that blue is hard for me to remember.



I have a cool little unit I got from ebay. It is a kit for cheap, but works pretty good. It will check and identify resistore, caps, inductors, and transistors, and diodes. works on a 9 volt supply and has a digital readout. I check every component before installation.

I've got one of those too. It identifies ANYthing...lol
I like it for very small value pico-farad-range caps to determine correct value

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Sat 09, 2017 11:04 pm 
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Should get my new 6X4 Monday. Want to get back to the Philco project. Today I worked on the shop test speakers. Changed to a 5X7 three way car speaker. I have two of them.
I am getting an old Magnavox tuner/amp/turn table. Needs repair, tube set. More fun.

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Wed 13, 2017 11:59 pm 
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Just about finished with the shop speakers. Then back to testing the Philco's. I got the new 6X4 in and ready to go. Still building signal boards for the railroad. Should be done with them soon.
The shop speakers will be mounted to the ceiling above my work bench.

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Thu 14, 2017 1:59 am 
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Speakers, signal boards, Philcos, 300b ... yikes what a busy busy bee you are young fella!

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Thu 14, 2017 3:19 am 
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Pbpix wrote:
Speakers, signal boards, Philcos, 300b ... yikes what a busy busy bee you are young fella!



All in due time Peter. I keep the fun in it.

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Thu 14, 2017 7:07 pm 
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Here is a preview of the test speakers for the shop
Attachment:
ts.jpg
ts.jpg [ 44.96 KiB | Viewed 2803 times ]

Notice, it is not the original Zenith speaker.

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Thu 14, 2017 8:58 pm 
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john8750 wrote:
Here is a preview of the test speakers for the shop
Attachment:
ts.jpg

Notice, it is not the original Zenith speaker.

I'm sure they'll probably sound "alright" but John, how do you know what the acoustically-proper box size & shape should be for that particular speaker? Or did you just pick anything that physically fit the size? Do you know if it should be ported or not?

I am under the impression that speaker enclosures are specifically designed around each different speaker for optimal acoustical qualities.
If I were to try to make a speaker enclosure, I'd be concerned that if I made a box of any-old size that maybe I'd be reducing the qualities instead of improving it. Y'know?

So who here knows this stuff? Chime in.

Will you be using a grille cloth cover?

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