After looking thru some of Broskie's stuff I came up with the attached schematic for a line stage. (my PC sound card had extremely low output).
Can anyone tell me what to expect for gain on this?
I was looking at his similar design Phono Stage, anyone have experience with any "Simple" Phono stages?
I would like to stay "Octal" but could also go with 9pins and switch up my schema to 6FQ7/6CG7. (more for looks and consistancy)
BTW MM cartridge in both my turntables.
Can anyone tell me what to expect for gain on this?
I was looking at his similar design Phono Stage, anyone have experience with any "Simple" Phono stages?
I would like to stay "Octal" but could also go with 9pins and switch up my schema to 6FQ7/6CG7. (more for looks and consistancy)
BTW MM cartridge in both my turntables.
Attachments
ADDITONAL ??? please look
Thanks!,
I am pretty sure the Schematic is OK, just I am confused as to how to calc the gain since it is a screwy topology. Broskie's explanation was pretty clear as to the advantages but "thin" on the math.
I looked at the cornet but there are SO many poles in the B+ I am assuming it is part of the EQ network, Looks too complicated for what I am trying to do. (I have very little vinyl and play it rarely) I just have a lot of extra mA's in the PS for the preamp and figured I would put it to use.
Not to "HIJACK" my own thread but I have been pondering a question maybe this is an appropriate forum to ask it.
Here's the scenario:
I am laying out my next few projects based upon the eventual system configuration that I want to achieve. I am currently out of work so funds are limited but I have a LOT of free time.
I am preparing a "listening room" in my basement, which will also double as my home office and computer room.
Since I spend a LOT of time on the computer and love all kinds of music my collection of MP3's has grown to the point that I have needed to upgrade the hard drive 3 times (120+GB now).
I have a very nice sound card but it has VERY low output. Thus the need for the preamp even though my 6V6 PP "workhorse" amp has plenty of gain it still can't drive the power section to beyond about 1/2 full output.
So (after the long winded explanation) I would like to achieve the following.
Using the 6V6PP amp I already have (about 8W/Channel) and another PP amp (TBD) I would like to "Bi-Amp" my Yamaha's
I addition I would like to add a "subwoofer" or "bass channel" for this I will tackle the challenge of getting about 20 Watts from 829B's in SET. Since I plan for this to be about 140hz and down @ 6db/octave and most sound below 400 is non directional I plan for it to be "Mono" with a single driver.
SOOO....
I need to "SUM" the L/R channels for this "mono" LP filter.
Oops Forgot to mention I plan to also insert an "Active Tube Crossover" between the preamp and the power amps.
Maybe I am missing something but I can't get a "grasp" on how to sum the signals without messing with the "stereo" separation of the signals for the rest of the system.
IE simply "connecting" them together would work backwards also?
What I am getting at is I need some sort of "buffer" correct?
Any suggestions from anyone would be appreciated.
Thanks!,
I am pretty sure the Schematic is OK, just I am confused as to how to calc the gain since it is a screwy topology. Broskie's explanation was pretty clear as to the advantages but "thin" on the math.
I looked at the cornet but there are SO many poles in the B+ I am assuming it is part of the EQ network, Looks too complicated for what I am trying to do. (I have very little vinyl and play it rarely) I just have a lot of extra mA's in the PS for the preamp and figured I would put it to use.
Not to "HIJACK" my own thread but I have been pondering a question maybe this is an appropriate forum to ask it.
Here's the scenario:
I am laying out my next few projects based upon the eventual system configuration that I want to achieve. I am currently out of work so funds are limited but I have a LOT of free time.
I am preparing a "listening room" in my basement, which will also double as my home office and computer room.
Since I spend a LOT of time on the computer and love all kinds of music my collection of MP3's has grown to the point that I have needed to upgrade the hard drive 3 times (120+GB now).
I have a very nice sound card but it has VERY low output. Thus the need for the preamp even though my 6V6 PP "workhorse" amp has plenty of gain it still can't drive the power section to beyond about 1/2 full output.
So (after the long winded explanation) I would like to achieve the following.
Using the 6V6PP amp I already have (about 8W/Channel) and another PP amp (TBD) I would like to "Bi-Amp" my Yamaha's
I addition I would like to add a "subwoofer" or "bass channel" for this I will tackle the challenge of getting about 20 Watts from 829B's in SET. Since I plan for this to be about 140hz and down @ 6db/octave and most sound below 400 is non directional I plan for it to be "Mono" with a single driver.
SOOO....
I need to "SUM" the L/R channels for this "mono" LP filter.
Oops Forgot to mention I plan to also insert an "Active Tube Crossover" between the preamp and the power amps.
Maybe I am missing something but I can't get a "grasp" on how to sum the signals without messing with the "stereo" separation of the signals for the rest of the system.
IE simply "connecting" them together would work backwards also?
What I am getting at is I need some sort of "buffer" correct?
Any suggestions from anyone would be appreciated.
you can easily calculate the gain of a grounded cathode design (with or without a cap) using this guide :
http://www.aikenamps.com/CommonCathode.htm
http://www.aikenamps.com/CommonCathode.htm
why is the output from your soundcard so low? what make is it?
a SET is a poor choice for a dedicated subwoofer channel. a mono sub is a bad choice anyway (long thread in the loudspeaker forum right now, i think)
if you decide to do mono anyway, solid state is a good choice, don't be afraid
yes, you need to buffer before summing, or do a stereo sub filter and sum afterwords. what is your preamp/filter choice (or future idea)?
a SET is a poor choice for a dedicated subwoofer channel. a mono sub is a bad choice anyway (long thread in the loudspeaker forum right now, i think)
if you decide to do mono anyway, solid state is a good choice, don't be afraid
yes, you need to buffer before summing, or do a stereo sub filter and sum afterwords. what is your preamp/filter choice (or future idea)?
here's a good thread on why not to use a mono sub (it' wasn't in the loudspeaker forum afterall, sorry). it's a mastering forum - those guys who use high end system to evaluate and/or tweak records before they're put out to the public :
http://www.gearslutz.com/board/mastering-forum/368901-2-1-monitoring-mastering-possible.html
http://www.gearslutz.com/board/mastering-forum/368901-2-1-monitoring-mastering-possible.html
After reading the post I came to a conclusion.
My initial theory is actually the CORRECT answer.
Here is how I got there.
I have read (can't remember where but published and reputable sources) that typical human hearing cannot differentiate sound sources below about 400hz this is also exponential to the octave so at 200hz were about 4 times less likely to identify the source location.
Example: Aside from left right front or back can you tell WHERE the "boom" of thunder came from? Maybe the "crack" (higher frequency) but the BOOM is hard to tell.
So making the assumption that the track was recorded and is being played back in "Acoustically perfect and identical rooms" (just to eliminate room acoustics) I see no reason why a "mono" sub woofer would be an issue. I agree with some that "summing" electrically the 2 channels will result in some "lost" information, ie something that "cancels" from L/R.
BUT, that would have to have been recorded directly to the track or with "stereo" mikes. Either way had I PERSONALLY been in that room the sounds would have "cancelled" before they got to my ears anyway and if they didn't I would not know whether they were from the left or right.
Since that is a SMALL portion of the sound information I can live with it being "lost" altogether in exchange for not pushing my speakers to the limit with long excursion @ low frequency. Remember no drivers suspension is perfect. Therefore, excessive low frequencies into the driver can "muddy" up the sound.
Also, relatively speaking (no pun intended) I can afford a much higher sensitivity in a woofer than I can the full range drivers. This leaves me with more room to play with a lower power "sub amp"
Example a 94 db@ 1W sub will allow me to use 1W for the equivalent output of my 88Db Speakers @ 4Watts or going backwards my 8 watt Fullrange setup gives me roughly 94DB SPL.
I can drive a single 94DB sub with 1 watt and have the same SPL.
Just "food for thought"
My initial theory is actually the CORRECT answer.
Here is how I got there.
I have read (can't remember where but published and reputable sources) that typical human hearing cannot differentiate sound sources below about 400hz this is also exponential to the octave so at 200hz were about 4 times less likely to identify the source location.
Example: Aside from left right front or back can you tell WHERE the "boom" of thunder came from? Maybe the "crack" (higher frequency) but the BOOM is hard to tell.
So making the assumption that the track was recorded and is being played back in "Acoustically perfect and identical rooms" (just to eliminate room acoustics) I see no reason why a "mono" sub woofer would be an issue. I agree with some that "summing" electrically the 2 channels will result in some "lost" information, ie something that "cancels" from L/R.
BUT, that would have to have been recorded directly to the track or with "stereo" mikes. Either way had I PERSONALLY been in that room the sounds would have "cancelled" before they got to my ears anyway and if they didn't I would not know whether they were from the left or right.
Since that is a SMALL portion of the sound information I can live with it being "lost" altogether in exchange for not pushing my speakers to the limit with long excursion @ low frequency. Remember no drivers suspension is perfect. Therefore, excessive low frequencies into the driver can "muddy" up the sound.
Also, relatively speaking (no pun intended) I can afford a much higher sensitivity in a woofer than I can the full range drivers. This leaves me with more room to play with a lower power "sub amp"
Example a 94 db@ 1W sub will allow me to use 1W for the equivalent output of my 88Db Speakers @ 4Watts or going backwards my 8 watt Fullrange setup gives me roughly 94DB SPL.
I can drive a single 94DB sub with 1 watt and have the same SPL.
Just "food for thought"
human hearing and music reproduction is two very different things. a lot is explained in that thread i linked to. while your thoughts are valid, it's really not a subject for this forum. i can say that i've never heard a mono sub fully integrated in any setup and very few stereo subs that did any good. and those that did where cut at 40-50Hz (and steep!) and helping out what was essentially fullrange speakers
1V (RMS?) should be enough for most (power) amps
my advice it to put some money into a decent DAC before doing a SET for your sub(s)
1V (RMS?) should be enough for most (power) amps
my advice it to put some money into a decent DAC before doing a SET for your sub(s)
also, a high sensitivity woofer needs a VERY large enclosure to do any good. depending on design it may not even do any real sub'ing. a high Z ouput SET is a rather poor choice for this
while you may need 1W _average_, you'll still need some headroom (i like 20dB) for real music (<-- yes yes modern music is compressed like crap, i know)
while you may need 1W _average_, you'll still need some headroom (i like 20dB) for real music (<-- yes yes modern music is compressed like crap, i know)
Off the top of my head, 3 types are candidates for the 1st gain block position: the 'SL7, the 'SJ7, and the 'AC7. You'll get a better price buying "12" V. heater versions and regulated 12 VDC supplies are very easy to build.
While the pentodes might be marginal in the noise factor dept., you don't have worries about adverse Miller capacitance/cartridge interactions.
With approx. 20 dB. gain in the line stage, a 'SN7 seems feasible in the 2nd gain block position.
makeb4break said:also, a high sensitivity woofer needs a VERY large enclosure to do any good. depending on design it may not even do any real sub'ing. a high Z ouput SET is a rather poor choice for this
while you may need 1W _average_, you'll still need some headroom (i like 20dB) for real music (<-- yes yes modern music is compressed like crap, i know)
Make,
I just got in to the group buy for Pete Millet's Xover boards. They are 24db/Octave.
You are correct though,
1: Probably going to need about 20Watts
2: Probably going to go PP pentode w/???
3: 3/db down point will be more like 80hz and it will be a BIG box and bandpass at that to be REALLY STEEP.
To move back to the threads original topic:
I think what I am going to do since I have the PS for it is adapt the cornet schematic for the phono section and then add 2 more channels to the preamp. From there I can then decide what to do with the xover board.
I had being playing with the idea of the tube xover for like a year now. When the group buy came up today I am starting to "rethink" the whole setup.
Maybe I will just have to look at a "bi-amped" speaker project.
Any suggestions as to "affordable" drivers that can play down in the 20hz range?
I have pretty good skills with enclosure design & construction so a DIY set of speakers is not an issue. It's just that drivers can get up into some hefty cost.
MB4B,
The group buy on the Millet Xover board came up out of nowhere. I had always been toying with the Idea of building an all tube crossover. So this "throws a wrench in the works" so to speak.
I think what I will do now is look into building my own Speakers. I have a LOT of experience with box building and passive networks etc after years in Car Audio. What I am thinking is to build a "3 Way" system. I would Bi-Amp a set of monitors using the Millet Board 2-Channel 2-Way.
The low pass channel would then be split 1/2 would be summed mono after a passive Xover to whatever F3 I choose for the sub, and the other half 6db Passive High pass at the input of the "mid" amp.
What I am wondering is if anyone has a suggestion for decent drivers, where to buy and a good starting point for driver size and type based upon a smallish (11x14) room? Power for would be in the 8-10 watt range PP.
The group buy on the Millet Xover board came up out of nowhere. I had always been toying with the Idea of building an all tube crossover. So this "throws a wrench in the works" so to speak.
I think what I will do now is look into building my own Speakers. I have a LOT of experience with box building and passive networks etc after years in Car Audio. What I am thinking is to build a "3 Way" system. I would Bi-Amp a set of monitors using the Millet Board 2-Channel 2-Way.
The low pass channel would then be split 1/2 would be summed mono after a passive Xover to whatever F3 I choose for the sub, and the other half 6db Passive High pass at the input of the "mid" amp.
What I am wondering is if anyone has a suggestion for decent drivers, where to buy and a good starting point for driver size and type based upon a smallish (11x14) room? Power for would be in the 8-10 watt range PP.
Speakers
I currently use a B&C 8PE21 8" midrange. I run it full range and get a fairly flat response in a small sealed box. Low enough to crossover to a good sub and high enough to crossover to a small format compression driver (~3 to 4kh). For the compression driver I like the small BMS drivers and a simple round horn.
I currently use a B&C 8PE21 8" midrange. I run it full range and get a fairly flat response in a small sealed box. Low enough to crossover to a good sub and high enough to crossover to a small format compression driver (~3 to 4kh). For the compression driver I like the small BMS drivers and a simple round horn.
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