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 Post subject: Re: 6V6 SE HiFi amp (new project)
PostPosted: Jan Fri 12, 2018 9:21 pm 
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glue_ru wrote:
A straight through amp, no knobs to play with?
I found an interesting twist to a single knob tone control, the AMZ Presence circuit, I want to try this in an upcoming project.
http://www.muzique.com/lab/tone3.htm
Thank you. Nice article interesting circuit.

For my way of thinking, I belive that a tone control such as that one, may have great benefit for a guitar amp where the player is an artist and wants the modified and "distorted" output to have certain characteristics for his performance as he is "creating" the modified and peculiar, unique sound as part of his art.

I on the other hand look to my HIFI amp with high hope of getting exact fidelity to the original recorded sound as delivered (such as it is on whatever media).
So I have played a bit with add-on tone controls, yes, .... but I really don't like the idea of ME altering the sound of a song ... mostly because i keep wondering if it might have been more enjoyable w/o the tone control.
And normally I listen to hours of recorded music and I don't want to have to get up and tweak the tones for every different song.
And I also, fundamentally, feel that if my amp "needs" to have a tone control to compensate for its shortcomings...then the amp has a flaw in fidelity.
And so I would always just want a TRUE HiFi amp where it does not "need" tone tweaking.

But that's just me.

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 Post subject: Re: 6V6 SE HiFi amp (new project)
PostPosted: Jan Fri 12, 2018 9:36 pm 
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john8750 wrote:
I love it when you talk amp stuff.


oooh... Just shut up a kiss me!
Image

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Last edited by Pbpix on Jan Fri 12, 2018 10:41 pm, edited 1 time in total.

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 Post subject: Re: 6V6 SE HiFi amp (new project)
PostPosted: Jan Fri 12, 2018 9:53 pm 
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Ok peter, enough of that love stuff. The music you like was recorded with analog equipment. Then it was converted to a digital signal. And then it is 'daked' back to analog. So how do you know how it should sound? The only way you could get a true resemblance is from original vinyl.

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 Post subject: Re: 6V6 SE HiFi amp (new project)
PostPosted: Jan Fri 12, 2018 9:55 pm 
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Pbpix wrote:
glue_ru wrote:
A straight through amp, no knobs to play with?
I found an interesting twist to a single knob tone control, the AMZ Presence circuit, I want to try this in an upcoming project.
http://www.muzique.com/lab/tone3.htm
Thank you. Nice article interesting circuit.

For my way of thinking, I belive that a tone control such as that one, may have great benefit for a guitar amp where the player is an artist and wants the modified and "distorted" output to have certain characteristics for his performance as he is "creating" the modified and peculiar, unique sound as part of his art.

I on the other hand look to my HIFI amp with high hope of getting exact fidelity to the original recorded sound as delivered (such as it is on whatever media).
So I have played a bit with add-on tone controls, yes, .... but I really don't like the idea of ME altering the sound of a song ... mostly because i keep wondering if it might have been more enjoyable w/o the tone control.
And normally I listen to hours of recorded music and I don't want to have to get up and tweak the tones for every different song.
And I also, fundamentally, feel that if my amp "needs" to have a tone control to compensate for its shortcomings...then the amp has a flaw in fidelity.
And so I would always just want a TRUE HiFi amp where it does not "need" tone tweaking.

But that's just me.


My project is for a guitar amp! which is why they may like the distortion effects it could do.
I'm the same way, I believe music artists have very carefully designed their music to be played "as-is"
Bass and treble controls mainly make up for a bad speaker choice or other equipment deficiencies
I play mostly at neutral settings on bass and treble, if anything I may bump bass up 1 or 2 to make
up for low freq hearing loss. (I hung around 40mm Bofors AAA guns as a kid with no hearing protection)

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 Post subject: Re: 6V6 SE HiFi amp (new project)
PostPosted: Jan Fri 12, 2018 10:50 pm 
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john8750 wrote:
Ok peter, enough of that love stuff. The music you like was recorded with analog equipment. Then it was converted to a digital signal. And then it is 'daked' back to analog. So how do you know how it should sound? The only way you could get a true resemblance is from original vinyl.

Well... even vinyl recording equipment wasn't/isn't "perfect" ...
And going from analog to digital and back again doesn't necessarily have to change the fidelity.
remember... the digital file is sampling the analog file at many points, hundreds maybe, and saving that p;oint on the analog line as a digital number of volts or whatever.... and it saves it and then later it replaces that digital number again with an analog voltage of that value.
So unless it is broken... the same signal going in replicated ( depending on how many sampling points) on the way out.

But in either case... I can't know or control that part.
So I have to take the music file presented to me as "original" as well as can be done.
So I don't want to CHANGE that because... why? I don't like the amount of bass? Who says there was more bass originally? Right?
So all I want is for my amp to reproduce EXACTLY as possible the signal I feed it from vinyl or CD or whatever.
HiFidelity is what that is called.
Fidelity means truth.
So hi truth.

As an example:
If your wife told you something that she says your sister said.
You don't know if your wife got it accurately or not.
.. but it is YOUR job to only ever retell the story exactly as your wife told you so as to not distort the truth beyond what you were given... Right?

Your wife's story represents the ORIGINAL "music" as best you know.
And you as the re-teller (amplifier) must not change her story as she told it.
You must be a high truth reteller.

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 Post subject: Re: 6V6 SE HiFi amp (new project)
PostPosted: Jan Thu 18, 2018 11:45 pm 
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Today I received a couple 820uf filter caps for the power supply.
I'm still waiting for a little warmer weather to go out in the garage to stain and finish the wood project box I've selected for this amp.
So I will add more as soon as more stuff arrives and then when that box is ready.. things will start moving quickly.

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 Post subject: Re: 6V6 SE HiFi amp (new project)
PostPosted: Jan Fri 19, 2018 2:37 am 
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Hi Peter. I have seen a .01 disc cap right across the filter caps. Is this just an idea from some, or is there a reason for it?
Seems like those big caps would be enough filtering.

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 Post subject: Re: 6V6 SE HiFi amp (new project)
PostPosted: Jan Fri 19, 2018 3:25 am 
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Hi all. That 6SL7 can drive a 6V6 into overdrive. If the B+ for the triode is 300v the 6SL7 can deliver 65v if the 6V6 has a grid leak resistor of 470k. With a plate resistor of 220k and a bypassed cathode resistor of 3200 ohms though a standard 3.3k will work well this from the 1964 rca tube manual. It will have a voltage gain of 46 so if you need more lash up the other half and get all the gain you can stand and more. If you do not bypass the cathode resistor the gain will drop but so will distortion and you can insert negative feedback at the cathode from the output. I would bypass the input stage cathode and put a gain control between the two stages. The frequency response as well as distortion will be better too with the feedback. Should make a good 4 watt amp that sounds good. Hope these suggestions are helpful.

Bob


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 Post subject: Re: 6V6 SE HiFi amp (new project)
PostPosted: Jan Fri 19, 2018 3:40 am 
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john8750 wrote:
Hi Peter. I have seen a .01 disc cap right across the filter caps. Is this just an idea from some, or is there a reason for it?
Seems like those big caps would be enough filtering.

The smaller cap in parallel is for short duration noise spikes.

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 Post subject: Re: 6V6 SE HiFi amp (new project)
PostPosted: Jan Fri 19, 2018 4:07 am 
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Audioman wrote:
Hi all. That 6SL7 can drive a 6V6 into overdrive. If the B+ for the triode is 300v the 6SL7 can deliver 65v if the 6V6 has a grid leak resistor of 470k. With a plate resistor of 220k and a bypassed cathode resistor of 3200 ohms though a standard 3.3k will work well this from the 1964 rca tube manual. It will have a voltage gain of 46 so if you need more lash up the other half and get all the gain you can stand and more. If you do not bypass the cathode resistor the gain will drop but so will distortion and you can insert negative feedback at the cathode from the output. I would bypass the input stage cathode and put a gain control between the two stages. The frequency response as well as distortion will be better too with the feedback. Should make a good 4 watt amp that sounds good. Hope these suggestions are helpful.

Bob

Hi Bob:
Thank you very much for the ideas.

The original print came from the Lacewood amp Ver 2. which used 6SN7

I'll be using his basic design but with the 6SL7 instead.

So I'll initially build it this way and see how it goes and then refer to your hints for any changes.
How do you feel this semi-final design will work?
Attachment:
lacewood 6sl7 - 6v6.jpg
lacewood 6sl7 - 6v6.jpg [ 58.11 KiB | Viewed 233 times ]

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 Post subject: Re: 6V6 SE HiFi amp (new project)
PostPosted: Jan Sun 28, 2018 7:55 pm 
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Peter, don't forget the tube rectifier :lol:

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