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 Post subject: Re: 6V6 / 6AQ5 PP Stereo Amp
PostPosted: Mar Sat 28, 2015 4:49 am 
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Btw, if you guys are just dead set on blowing up your computer, preamp, or whatever is connected to the input, and potentially electrocuting yourself the Paraphaser can be built with a hot chassis power power supply too.


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 Post subject: Re: 6V6 / 6AQ5 PP Stereo Amp
PostPosted: Mar Sat 28, 2015 5:00 am 
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Flipperhome wrote:
Btw, if you guys are just dead set on blowing up your computer, preamp, or whatever is connected to the input, and potentially electrocuting yourself the Paraphaser can be built with a hot chassis power power supply too.



Hey John... how's it sound NOW?
Image

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 Post subject: Re: 6V6 / 6AQ5 PP Stereo Amp
PostPosted: Mar Sat 28, 2015 5:09 am 
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john8750 wrote:
Forgot to ask if I need the 10 or 8K OPT's.
I want to get them on order.
Is there a standard ID just for transformers with the UL taps?
Changed my mind about the 1019 with a built in amp. I think I will have only the RIAA preamp on board.
That should make things easier to work with.

Hi John:
Flip advised that 8K is best if we are going to be using Ultra Linear.

So that's either of these. They all have UL taps:
1.) XPP10-8-8k
$17.00
https://www.edcorusa.com/xpp10-8-8k

2.)GXPP10-8-8k
$27.00
https://www.edcorusa.com/gxpp10-8-8k

3.) CXPP25-MS-8k
$58.00
https://www.edcorusa.com/cxpp25-ms-8k

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 Post subject: Re: 6V6 / 6AQ5 PP Stereo Amp
PostPosted: Mar Sat 28, 2015 5:59 am 
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Pbpix wrote:
Flipperhome wrote:
Btw, if you guys are just dead set on blowing up your computer, preamp, or whatever is connected to the input, and potentially electrocuting yourself the Paraphaser can be built with a hot chassis power power supply too.



Hey John... how's it sound NOW?
Image



MORE POWER CAPTAIN>>>>>>>>>>>> :shock:

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If I did something right, I made a mistake.


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 Post subject: Re: 6V6 / 6AQ5 PP Stereo Amp
PostPosted: Mar Sat 28, 2015 6:01 am 
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Flipperhome wrote:
Btw, if you guys are just dead set on blowing up your computer, preamp, or whatever is connected to the input, and potentially electrocuting yourself the Paraphaser can be built with a hot chassis power power supply too.



I already have all the transformers Flip. So I want mine just like you did it. Coming soon....

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 Post subject: Re: 6V6 / 6AQ5 PP Stereo Amp
PostPosted: Mar Sat 28, 2015 6:02 am 
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Pbpix wrote:
john8750 wrote:
Forgot to ask if I need the 10 or 8K OPT's.
I want to get them on order.
Is there a standard ID just for transformers with the UL taps?
Changed my mind about the 1019 with a built in amp. I think I will have only the RIAA preamp on board.
That should make things easier to work with.

Hi John:
Flip advised that 8K is best if we are going to be using Ultra Linear.

So that's either of these. They all have UL taps:
1.) XPP10-8-8k
$17.00
https://www.edcorusa.com/xpp10-8-8k

2.)GXPP10-8-8k
$27.00
https://www.edcorusa.com/gxpp10-8-8k

3.) CXPP25-MS-8k
$58.00
https://www.edcorusa.com/cxpp25-ms-8k



Thanks Peter. The $27 one it shall be.

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If I did something right, I made a mistake.


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 Post subject: Re: 6V6 / 6AQ5 PP Stereo Amp
PostPosted: Mar Sat 28, 2015 6:12 am 
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Hey John... here's a regulated version ofthe supply. I put the LR8N3-G HV regulator to work.
But I had to set the B+ back 5v to +230v ... to keep the output at least 15v below the input for optimal ripple reduction as well as regulation: Works nicely with a heatsink on the TIP50. It's only regulating about 20v @ 115ma ... so that means it has to dissipate about 2-1/2 watts.

As a side note:
This regulator is nice.. but I'm not sure it's really worth the bother .... after all we're only replacing one 120 ohm resistor and a 470uf cap .... and even though the ripple is next to nothing... it wasn't bad before at 100mv. So the choice is up to you.

Attachment:
6aq5 supply reg.jpg
6aq5 supply reg.jpg [ 64.87 KiB | Viewed 3085 times ]

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 Post subject: Re: 6V6 / 6AQ5 PP Stereo Amp
PostPosted: Mar Sat 28, 2015 6:38 am 
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Pbpix wrote:
Hey John... here's a regulated version ofthe supply. I put the LR8N3-G HV regulator to work.
But I had to set the B+ back 5v to +230v ... to keep the output at least 15v below the input for optimal ripple reduction as well as regulation: Works nicely with a heatsink on the TIP50. It's only regulating about 20v @ 115ma ... so that means it has to dissipate about 2-1/2 watts.

As a side note:
This regulator is nice.. but I'm not sure it's really worth the bother .... after all we're only replacing one 120 ohm resistor and a 470uf cap .... and even though the ripple is next to nothing... it wasn't bad before at 100mv. So the choice is up to you.

Attachment:
6aq5 supply reg.jpg



What about the CCS's? I will do it the way you suggest.
You are doing a lot of fun work there.
Thank you.

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If I did something right, I made a mistake.


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 Post subject: Re: 6V6 / 6AQ5 PP Stereo Amp
PostPosted: Mar Sat 28, 2015 6:51 am 
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john8750 wrote:
Pbpix wrote:
Hey John... here's a regulated version ofthe supply. I put the LR8N3-G HV regulator to work.
But I had to set the B+ back 5v to +230v ... to keep the output at least 15v below the input for optimal ripple reduction as well as regulation: Works nicely with a heatsink on the TIP50. It's only regulating about 20v @ 115ma ... so that means it has to dissipate about 2-1/2 watts.

As a side note:
This regulator is nice.. but I'm not sure it's really worth the bother .... after all we're only replacing one 120 ohm resistor and a 470uf cap .... and even though the ripple is next to nothing... it wasn't bad before at 100mv. So the choice is up to you.

Attachment:
6aq5 supply reg.jpg



What about the CCS's? I will do it the way you suggest.
You are doing a lot of fun work there.
Thank you.

What about the CCS? You make it same as the 5902 amp except use a 51 ohm resistor.
For 25ma current:

1.25/.025a = 50 ohms

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 Post subject: Re: 6V6 / 6AQ5 PP Stereo Amp
PostPosted: Mar Sat 28, 2015 10:00 pm 
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Flipperhome wrote:
Btw, if you guys are just dead set on blowing up your computer, preamp, or whatever is connected to the input, and potentially electrocuting yourself the Paraphaser can be built with a hot chassis power power supply too.

Hi Flip:
That's interesting. It seems a bit complex.
Why don't you add that schematic now too over at the Paraphaser thread... and I'll go over there and look for it.

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 Post subject: Re: 6V6 / 6AQ5 PP Stereo Amp
PostPosted: Mar Sun 29, 2015 3:30 am 
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Joined: Dec Mon 29, 2014 9:39 pm
Posts: 5159
Location: Los Angeles
Pbpix wrote:
john8750 wrote:
Pbpix wrote:
Hey John... here's a regulated version ofthe supply. I put the LR8N3-G HV regulator to work.
But I had to set the B+ back 5v to +230v ... to keep the output at least 15v below the input for optimal ripple reduction as well as regulation: Works nicely with a heatsink on the TIP50. It's only regulating about 20v @ 115ma ... so that means it has to dissipate about 2-1/2 watts.

As a side note:
This regulator is nice.. but I'm not sure it's really worth the bother .... after all we're only replacing one 120 ohm resistor and a 470uf cap .... and even though the ripple is next to nothing... it wasn't bad before at 100mv. So the choice is up to you.

Attachment:
6aq5 supply reg.jpg



What about the CCS's? I will do it the way you suggest.
You are doing a lot of fun work there.
Thank you.

What about the CCS? You make it same as the 5902 amp except use a 51 ohm resistor.
For 25ma current:

1.25/.025a = 50 ohms



Roger that Professor. I was wondering that if the B+ is regulated, will the CCS still be needed.
I guess I was mixing voltage regulation with current regulation.

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If I did something right, I made a mistake.


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 Post subject: Re: 6V6 / 6AQ5 PP Stereo Amp
PostPosted: Mar Sun 29, 2015 3:39 am 
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Pbpix wrote:
Flipperhome wrote:
Btw, if you guys are just dead set on blowing up your computer, preamp, or whatever is connected to the input, and potentially electrocuting yourself the Paraphaser can be built with a hot chassis power power supply too.
Hi Flip:
That's interesting. It seems a bit complex.
Why don't you add that schematic now too over at the Paraphaser thread... and I'll go over there and look for it.
No need. Mine is built and John has the transformers. Just imagine yours with a negative supply added.

As for 'complex', fixed bias is superior to any cathode bias and worth it for the improved bass from line transformers.


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 Post subject: Re: 6V6 / 6AQ5 PP Stereo Amp
PostPosted: Mar Sun 29, 2015 4:46 am 
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Flipperhome wrote:
Pbpix wrote:
Flipperhome wrote:
Btw, if you guys are just dead set on blowing up your computer, preamp, or whatever is connected to the input, and potentially electrocuting yourself the Paraphaser can be built with a hot chassis power power supply too.
Hi Flip:
That's interesting. It seems a bit complex.
Why don't you add that schematic now too over at the Paraphaser thread... and I'll go over there and look for it.
No need. Mine is built and John has the transformers. Just imagine yours with a negative supply added.

As for 'complex', fixed bias is superior to any cathode bias and worth it for the improved bass from line transformers.

I was using the term "complex" about the pwr not the amp.

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 Post subject: Re: 6V6 / 6AQ5 PP Stereo Amp
PostPosted: Mar Sun 29, 2015 4:53 am 
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john8750 wrote:

Roger that Professor. I was wondering that if the B+ is regulated, will the CCS still be needed.
I guess I was mixing voltage regulation with current regulation.

Well... there two areas of concern:
1.) ....overall system "power supply" regulation
and
2.) Audio output amp area ... "signal" current regulation through the tubes and OT.

The LR8N3 is a (3-terminal) HV voltage regulator meant to adjust the overall system power supply voltage.
The CCSs on the other hand are used in the output signal loop area to keep current fixed for improved "self-bias" regulation.

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 Post subject: Re: 6V6 / 6AQ5 PP Stereo Amp
PostPosted: Mar Sun 29, 2015 6:19 am 
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Pbpix wrote:
Flipperhome wrote:
Pbpix wrote:
Hi Flip:
That's interesting. It seems a bit complex.
Why don't you add that schematic now too over at the Paraphaser thread... and I'll go over there and look for it.
No need. Mine is built and John has the transformers. Just imagine yours with a negative supply added.

As for 'complex', fixed bias is superior to any cathode bias and worth it for the improved bass from line transformers.

I was using the term "complex" about the pwr not the amp.
I know. You need the 'power' negative rail for the fixed bias.


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 Post subject: Re: 6V6 / 6AQ5 PP Stereo Amp
PostPosted: Mar Sun 29, 2015 6:28 am 
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Sorry guys. I am just a little confused, as usual, about the B+ supplying plate voltage, and Cathode current being regulated.
This is a great learning experience for me and appreciate your help..

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 Post subject: Re: 6V6 / 6AQ5 PP Stereo Amp
PostPosted: Mar Sun 29, 2015 7:40 am 
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Flipperhome wrote:
I know. You need the 'power' negative rail for the fixed bias.

Sure.
Depends, I guess, on how one chooses to do it.

When I tested "fixed bias" for my 5902 amp I did it a little differently:
... since fixed bias requires almost no current, I just borrowed some of the 25.2 volt AC filament voltage. At that point I taped in with a 1N4007 (reversed) and a little pi-filter with a cpl caps.
I fed that to a variable resistor arrangement. So no extra "negative rail" needed.
Voila! Worked like a champ.
Image

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 Post subject: Re: 6V6 / 6AQ5 PP Stereo Amp
PostPosted: Mar Sun 29, 2015 7:59 am 
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Pbpix wrote:
Flipperhome wrote:
I know. You need the 'power' negative rail for the fixed bias.

Sure.
Depends, I guess, on how one chooses to do it.

When I tested "fixed bias" for my 5902 amp I did it a little differently:
... since fixed bias requires almost no current, I just borrowed some of the 25.2 volt AC filament voltage. At that point I taped in with a 1N4007 (reversed) and a little pi-filter with a cpl caps.
I fed that to a variable resistor arrangement. So no extra "negative rail" needed.
Voila! Worked like a champ.
I hate to break it to you but -21 V is a negative rail.


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 Post subject: Re: 6V6 / 6AQ5 PP Stereo Amp
PostPosted: Mar Sun 29, 2015 8:20 am 
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john8750 wrote:
Sorry guys. I am just a little confused, as usual, about the B+ supplying plate voltage, and Cathode current being regulated.
This is a great learning experience for me and appreciate your help..

We are using Class AB:
( for explanation ... lets start with a typical cathode bias resistor of 540 ohms.)

Cathode current we want (25ma) is initially set up for zero signal input. That's the bias point.
In this case about +13.5v on the cathode. [13.5v / 540 ohms = 25ma]

The grid has a reference through a 220k resistor to ground.
So the grid is essentially at 0v.

But since the cathode is +13.5v more positive.... that makes the grid actually -13.5v negative with respect to the cathode. ok?

OK... With -13.5 volts on the grid, the tube can only conduct about 25ma current.
So it's "on" but not a whole lot. ( it's initially in class-A state)

When signal comes along the grid goes MORE positive, turning on the tube current more .( it modulates the plate voltage and current in the tube .....and those current variations are felt in the OT... producing sound in the speaker.
When a signal comes in and the tube current varies into more or less it goes into class B.
So it goes from A to B and so it's called AB.

But the problem is that... as the signal turns on the tube more or less... the extra current variations go trough the cathode resistor too.

That extra current in the resistor changes the voltage drop across it and that changes the 13.5 volt bias point in direct opposition to the input signal... out of phase.
So it's like stepping on the gas and brake at the same time.
So part of the input signal gets canceled ... reducing it. It's a form of negative feed back.
To avoid this ... we use a cathode by-pass cap giving the input signal a lower impedance signal path right around the resistor. So the current changes can occur in the tube but some is set by the resistor and some is developed through the by-pass cap.
This allows the resistor to keep the bias point at -13.5 volt and the signal current variations go through the by-pass cap and the voltage across the bias resistor doesn't change.

So we are using a CCS instead of a cathode resistor. ( our CCS just acts as a variable resistor):
We want a variable cathode resistor (CCS) because:
.... as I explained above...a fixed resistor works fine for bias as long as all tubes are the same. When they are all perfectly equal... then we can count on the 540 ohm cathode resistor creating -13.5 v for each tube because each tube at -13.5 volts will turn on exactly 25ma of current.

But all tubes age and vary.

So we could use a different resistor for each tube.. or a pot. That works fine... as long as you set it with a meter as the tubes change or age.

That's not perfect. But a CCS is automatic.
We set the CCS for 25ma .... and it adjusts it's internal resistance to look like 540 ohms to hold the current at 25ma... great.
Even if the tube gets old the CCS can vary inside to STILL get 25ma... even if it has to vary it's resistance say ... up to 565 or down to 520 or whatever it needs to gets 25ma through the tube.

That's it!

An "auto-magic" variable cathode bias resistor ... and it's called a CCS. Constant Current Source.

The by pass cap HAS to be used around a CCS too.
In fact... without it... no sound can happen.
This is because the CCS is so fast that every tiny change in input signal is offset completely by the CCS ... ( it's always doing this so perfectly in order for it to try keep the bias point at 25ma)... so essentially nothing can happen.

True gas and brake at the same time.

So we must put a nice big cap to bypass the CCS....
Now ALL the signal variations can go around the CCS.
So the CCS acts to hold the bias point perfectly at 25ma... and the signal current variations flow through the by-pass cap. The larger the cap.. the lower the impedance to low freq signals.

Nice.

_________________
To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
-Emerson


Last edited by Pbpix on Mar Sun 29, 2015 8:47 am, edited 2 times in total.

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 Post subject: Re: 6V6 / 6AQ5 PP Stereo Amp
PostPosted: Mar Sun 29, 2015 8:39 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 23829
Location: Haledon, NJ, usa
Flipperhome wrote:
Pbpix wrote:
Flipperhome wrote:
I know. You need the 'power' negative rail for the fixed bias.

Sure.
Depends, I guess, on how one chooses to do it.

When I tested "fixed bias" for my 5902 amp I did it a little differently:
... since fixed bias requires almost no current, I just borrowed some of the 25.2 volt AC filament voltage. At that point I taped in with a 1N4007 (reversed) and a little pi-filter with a cpl caps.
I fed that to a variable resistor arrangement. So no extra "negative rail" needed.
Voila! Worked like a champ.
I hate to break it to you but -21 V is a negative rail.

Duh.. yes I know ...of course.. but I just meant I could tap a little off the filaments without having to build a typical full, mirror-image "classic" type +/- dual power supply.
But it's semantics.

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