Pass Amps- JUst insensitive or is something wrong with my ideas and builds?

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mpmarino

mpmarino

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Joined 2004
I went straight to R-K's hand drawn from many years ago

http://www.diyaudio.com/forums/atta...-ns10-lineamp-pcb-threshold_ns10_original.pdf

I used MPSA18 for NPN and BCxxxx (the right way around :)) for PNP. There is no problem substituting.

You'd have to keep in mind that this is an old design and it's not a 'hot topic' right now. You'd probably be alone in the build and would have to roll your own PCB. Little support. I had some trouble at first but ended up getting it going on my own. I am not an ace like some of these other guys. I'm happily using a SMPS :devilr:

http://www.diyaudio.com/forums/pass...gh-end-off-topic-thread-2226.html#post4949761

I did end up building the RIAA section, and use it every day.

I mentioned it as it probably meets the criteria you stated. I was gone from the forum for many years and missed a lot - so there are likely better options out there, but this is a piece of audio history so I went for it.
 
Nelson Pass

Nelson Pass

The one and only
Joined 2001
Paid Member
VictoriaGuy said:
The loudest passages from the music CDs I tested (I checked a few more after my previous post) were about 0.9 volts rms at the CDP output jacks.
Click to expand...

I don't think you want to be talking in terms of rms for this - the peak to
average ratio for music is usually somewhere in the 10 to 20 dB range.

What you want to look for is peak voltage, which for 2 V rms output rating
translates to 2.8 V peaks, or 25 watts peak into 8 ohms if you have 14 dB
amplifier gain.

I have seen enough wav files to note that 0 dB (max) is routinely hit, not
that it's always a good thing.
 
6

6c4c

Member
Joined 2011
Nelson Pass said:
the peak to
average ratio for music is usually somewhere in the 10 to 20 dB range.

2 V rms output rating translates to 2.8 V peaks, or 25 watts peak into 8 ohms if you have 14 dB amplifier gain.
Click to expand...
So, what is the "average listenning power" must be to avoid clipping 25 watt amp (with 14dB gain)? From 0,125 to 1.25 watt? Because if I know "average listening power" and sensitivity of my speakers (and distance from speakers to me) I can understand (calculate) is rated power of amp enough or not.
 
V

VictoriaGuy

Member
Joined 2008
juma said:
VictoriaGuy,
if you decide to go for that pink/green NS10 schematic (post #99) please have in mind that R10/R11 ratio sets the gain of that preamp and, as drawn, the gain will be way over 20dB. To lower it to reasonable value raise the R11 to 1k - 1k5.
Click to expand...

Thanks for that tip.

mpmarino said:
I went straight to R-K's hand drawn from many years ago

http://www.diyaudio.com/forums/atta...-ns10-lineamp-pcb-threshold_ns10_original.pdf

I used MPSA18 for NPN and BCxxxx (the right way around :)) for PNP. There is no problem substituting.
Click to expand...
Thanks for that info - most helpful!
I discovered (after my last post/questions about the NS10) the 'original' info from R-K. That definitely looks like the way to go - and you agreed.
Most of the NS10 threads are in the style of "I've got a secret" ... lots of reverse engineering back-and-forth with not a lot of usable information for a beginner, so I was happy to find the info from R-K.
mpmarino said:
You'd have to keep in mind that this is an old design and it's not a 'hot topic' right now. You'd probably be alone in the build and would have to roll your own PCB. Little support.
Click to expand...
That's not a huge problem for me -believe it or not - when I'm making a low-budget 'breadboard' project with 'off the shelf' cheap parts, most of which I have here. It's playing with 'unobtanium' parts and blowing them up (avoided so far) that gets me nervous!

There are some PCB ideas published in the NS10 threads, so I'm pretty confident I can work from those or even wire something up on perfboard.
I built up my F6 (with the Hammond 850G) using a scrap of fiberglass from my boat building hobby. I don't get much pleasure in stuffing a PCB I've bought, though I know that's usually the best path to a circuit that works without problems. I made the BOSOZ PCBs with toner transfer, so I can do that pretty easily.

I'll let y'all know if I build an NS10 or something similar....

Thanks again for the quick replies to my questions.
 
V

VictoriaGuy

Member
Joined 2008
Dennis Hui said:
I stumbled upon this site:

Album list - Dynamic Range Database

They have quite a lot of info on peak vs rms, something even at
the track level.
Click to expand...

Dennis-
Thanks for that link.
Is there an 'explanation page' there that explains the details?
All I found was listings of albums with 'ratings' (apparently the greater the dynamic range, the better?), and clicking on the album title gave a track listing with dB numbers for each track. Still, quite interesting stuff...
 
V

VictoriaGuy

Member
Joined 2008
VictoriaGuy said:
F6 has a published gain of 14 dB and maximum published output of 25 watts into 8 ohms.
That's about a 5-times voltage gain?

So the very loudest possible output from my CDP -from a 0 dB CD recording - 2 volts rms- would produce 10 volts at the speaker terminals of the F6, with no attenuation or preamp gain between the CDP and the F6 - a 'straight in' connection.. Into an 8 ohm load, that would be 12.5 watts power to the speakers.
Click to expand...

Nelson Pass said:
I don't think you want to be talking in terms of rms for this - the peak to
average ratio for music is usually somewhere in the 10 to 20 dB range.

What you want to look for is peak voltage, which for 2 V rms output rating
translates to 2.8 V peaks, or 25 watts peak into 8 ohms if you have 14 dB
amplifier gain.
Click to expand...

So, is there some 'standard' for audio power?
When I looked on 'the internet' plenty of explanations talked about Vrms and Irms and even Prms (sic)..
So, for input levels it's Vrms ( 0dB, 2v rms from a CDP, for example) but for output it's Vpeak that should be used?
 
S

stocktrader200

Member
Joined 2008
OPA2134 is a great op amp, so any circuit with it will be really good
your F6 requires about 12 db of gain ( 4x ) to get 5 watts output from your CD.
A tube preamp sounds better due to the tube distortion added.
Tubes can also drive higher p-p voltages into 20 kohm loads such as a passive tone control stack.
 
B

Bare

Member
Joined 2001
Erm.. Whatever You believe.
MY George Wright tube pre of long service and considered decent by most.. including myself (hey! I paid $$ for it)
Sounded like Shite when fitted to MY F6.
No need to perpetuate unsubstantiated folklore.. there's more than enough in this seemingly endless thread.. already.
 
S

stocktrader200

Member
Joined 2008
I built mine from scratch with 6922 , makes the music and vocals sound as if they are in the room. I am a Solid State guy, but this thing really is that tiny missing piece.
my System: input > OPA 2134 > volume control > 6922 tube pre Gain = 15 > tone controls > Honey Badger mosfet amp > speakers
Bonus ** it fades the music in when first turned on **
 
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P

plasnu

Member
Joined 2011
J

JimT

Member
Joined 2004
VictoriaGuy said:
So, is there some 'standard' for audio power?
When I looked on 'the internet' plenty of explanations talked about Vrms and Irms and even Prms (sic)..
So, for input levels it's Vrms ( 0dB, 2v rms from a CDP, for example) but for output it's Vpeak that should be used?
Click to expand...

Not a direct answer to your question, but you do need to figure out how much power you need. Pano has a nice test for this and there are lots of people who have run the test and provided their info.

http://www.diyaudio.com/forums/mult...much-voltage-power-do-your-speakers-need.html

PS: I find these Pass DIY amps to have the right amount of gain for their output power.


Jim
 
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R

Russellc

Member
Joined 2003
Paid Member
fabrice63 said:
VictoriaGuy , why dont you give your F6 an nice pair of wonderful < 95 db speakers , no need of any preamp .

and the all thing will sing as you like .....LOUD :D

make it simple ;)


.
Click to expand...

Yup, makes a huge difference. Anyone here that isnt wise to the combination of First Watt amps and high efficiency speakers has missed the main point in my opinion. Or, like /need low volume listening.

There is a good reason why people are willing to pay 3-4k on the commercial units. The majority of folks here use high efficiency speakers, horns or whatever, Altec etc. I have used Altec, classic JBL horn/waveguide stuff, econowaves, and lately, Tekton speakers, which I can not recommend strongly enough...Enzo pair in my case. A F6 will be capable of blowing you out of your listening room.


Russellc
 
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D

Dennis Hui

Member
Joined 2002
Paid Member
Russellc said:
Yup, makes a huge difference. Anyone here that isnt wise to the combination of First Watt amps and high efficiency speakers has missed the main point in my opinion. Or, like /need low volume listening.

There is a good reason why people are willing to pay 3-4k on the commercial units. The majority of folks here use high efficiency speakers, horns or whatever, Altec etc.


Russellc
Click to expand...

I'm in a small room so even lower efficiency speakers (90dB) have worked fine for me. For a few months, I was using an F6 driven
directly from an Oppo player (2.1V RMS max output) and trimming the volume using the player's digital control. I did not find the
volume lacking across the materials I played even though I could get at most 14W or so vs the F6's max 25W.

Recently I tried a 10dB gain preamp with an F4. Now the power is limited to less than 6W and volume was a bit low on some materials.
So for me it seems 14dB of gain is adequate but 10dB is not quite enough.

Cheers,
Dennis
 
V

VictoriaGuy

Member
Joined 2008
fabrice63 said:
VictoriaGuy , why dont you give your F6 an nice pair of wonderful < 95 db speakers , no need of any preamp .
.
Click to expand...

You probably mean >95dB?
I do have some sensitive speakers.
But, that's not the point.

You've changed your ideas?
fabrice63 said:
VictoriaGuy , you choose the wrong trafo , your implementation is rather poor , components are cheapy ones , power supply is NOT what it should be , what else .... :rolleyes:

F6 is an great amp , but it has to be build the right way , and this way is the BETTER way , not the cheapy one ...

if you want the best from your (any) device give it the best , in every way ;)

.
Click to expand...
 
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