It's the preamp causing that as with the Schiit Saga S preamp the treble sounded better. I noticed the change in sound when I substituted the Sony preamp for it before redoing the crossover.
The sound has to travel through a lot more active devices inthe Sony, whereas the Schiit I ran in passive mode, but sounded equally as good in active mode.
The sound has to travel through a lot more active devices inthe Sony, whereas the Schiit I ran in passive mode, but sounded equally as good in active mode.
So I'm thinking of taking this speaker and redoing it as an open baffle design given I recently did an open baffle with a pair of RCA woofers a Midax and a tweeter that sounds very good.
I'll use 3/4" plywood for the baffle and I'll mount the drivers from the front.
Would a 2' X 4' piece of plywood be large enough for a 15" woofer, three tweeters arranged in a triangle configuration and a ribbon tweeter? The height will not be exactly 4' as I'll trim it down to size, but the width will be 2'.
All I need to do is figure a good way to cut the holes for the three Jensen tweeters. I originally used a 4" hole cutter which I think was moreso made for drywall and it didn't do too good of a job. The hole for the ribbon tweeter may be harder to do given the ribbon is square, although if I cut it to the exact size I can wedge it in there and mount it similar to how I have it currently mounted.
The woofer will be at the bottom. The Jensen tweeters will be right above it and the ribbon will be right above the Jensen tweeters.
The only issue then is that I will need to find something to put my 32" HDTV on.
Now should I do it like I did the other open baffle and use two triangular pieces on the side to secure it to the base or is there a better way for a person who normally does not work with wood and has only a few tools?
I would make the base as deep as the current box and likely will need to figure out a way to weight it down so it doesn't tip over forward. I might set the Magnavox amp on the base which will provide plenty of weight.
However if I do that I'll need to figure a way to make the milliammeters and the bias adjustments visible and accessible. I might see if I can move the bias pots to right beside the meters instead of on top of the chassis. That way I can cut a little square hole in the bottom of the baffle and have easy access.
I'll use 3/4" plywood for the baffle and I'll mount the drivers from the front.
Would a 2' X 4' piece of plywood be large enough for a 15" woofer, three tweeters arranged in a triangle configuration and a ribbon tweeter? The height will not be exactly 4' as I'll trim it down to size, but the width will be 2'.
All I need to do is figure a good way to cut the holes for the three Jensen tweeters. I originally used a 4" hole cutter which I think was moreso made for drywall and it didn't do too good of a job. The hole for the ribbon tweeter may be harder to do given the ribbon is square, although if I cut it to the exact size I can wedge it in there and mount it similar to how I have it currently mounted.
The woofer will be at the bottom. The Jensen tweeters will be right above it and the ribbon will be right above the Jensen tweeters.
The only issue then is that I will need to find something to put my 32" HDTV on.
Now should I do it like I did the other open baffle and use two triangular pieces on the side to secure it to the base or is there a better way for a person who normally does not work with wood and has only a few tools?
I would make the base as deep as the current box and likely will need to figure out a way to weight it down so it doesn't tip over forward. I might set the Magnavox amp on the base which will provide plenty of weight.
However if I do that I'll need to figure a way to make the milliammeters and the bias adjustments visible and accessible. I might see if I can move the bias pots to right beside the meters instead of on top of the chassis. That way I can cut a little square hole in the bottom of the baffle and have easy access.
So I got the speaker done and am well pleased with the sound.
I listened to the speaker a bit late last night streaming NPR from my PC as they have a jazz program late at night. The speaker sounds quite good.
One thing I noticed is the speaker sounds more clear which is likely because the open back box was coloring the bass making it sound darker.
What I may do is paint the area of the amp chassis around the meters so that it blends in better.
I listened to the speaker a bit late last night streaming NPR from my PC as they have a jazz program late at night. The speaker sounds quite good.
One thing I noticed is the speaker sounds more clear which is likely because the open back box was coloring the bass making it sound darker.
What I may do is paint the area of the amp chassis around the meters so that it blends in better.
Listened to this speaker and for the most part it sounds great, however when listening to the song Magic by Olivia Newton John there's a drum part in the chorus that goes from barely noticeable to easily heard based on how the lower midbass is reproduced by the speaker and on this speaker the drum part doesn't sound quite right, however this speaker is not for critical listening so that doesn't matter as much.
If I really wanted to fix it I could build an open baffle sub. I found this driver.
https://www.madisoundspeakerstore.c...udience-bianco-15ob350-15-open-baffle-woofer/
and I have a 2' X 2' piece of wood left over. I'd add a passive 12dB/octave high pass on the Magnavox amp and whatever amp I'll use for the added woofer I'll add a passive 12 dB/octave low pass. Any gain lost due to the high pass can be made up by turning up the level control on the stereo to mono summing box I made using a single tube.
I could use another 4' X 2' panel then cut it to the same height as the existing panel and use the 2' X 2' panel for the bottom. I'd likely use either 70Hz or 80Hz for the crossover frequency.
I'd prefer a tube amp, however the Magnavox amp already serves double duty as a room heater and another tube amp would heat up the room more.
If I really wanted to fix it I could build an open baffle sub. I found this driver.
https://www.madisoundspeakerstore.c...udience-bianco-15ob350-15-open-baffle-woofer/
and I have a 2' X 2' piece of wood left over. I'd add a passive 12dB/octave high pass on the Magnavox amp and whatever amp I'll use for the added woofer I'll add a passive 12 dB/octave low pass. Any gain lost due to the high pass can be made up by turning up the level control on the stereo to mono summing box I made using a single tube.
I could use another 4' X 2' panel then cut it to the same height as the existing panel and use the 2' X 2' panel for the bottom. I'd likely use either 70Hz or 80Hz for the crossover frequency.
I'd prefer a tube amp, however the Magnavox amp already serves double duty as a room heater and another tube amp would heat up the room more.
So it looks like the zobel on the Jensen tweeters is needed.
I'll need a 2.9uF cap and a 7.1 ohm resistor. I have a 2.7uF cap which should be close enough and I think I have a 7 ohm resistor.
Here's the data with the zobel
Here's the speaker without the zobel.
Here's the speaker with the zobel
I'll need a 2.9uF cap and a 7.1 ohm resistor. I have a 2.7uF cap which should be close enough and I think I have a 7 ohm resistor.
Here's the data with the zobel
Here's the speaker without the zobel.
Here's the speaker with the zobel
Would it be better if the Zobel network equalized the impedance over a wider frequency range? The "data with the zobel" impedance plot shows a still-large peak in the impedance between 1kHz and 10kHz.
I love your passion for the continued use of some old/classic drivers. 12 dB oct. for the old tweeters is a must as they are probably quite delicate.
No shame in using a 'Super Tweeter'.
However, in the last picture, the placement of the amp. will lead to vibration of the vacuum tubes > and hence, 'microphonics' over time 😕
The issue there was the zobel for the woofer was wrong.
Here's the data with the correct zobel. The only thing I question is the dip down to 2.39 ohms at 12.18kHz. .
When the Emerson console was being parted out, I couldn't pass up the drivers as there's no telling what would have happened to them.
They originally had a 6dB/octave crossover, but I've found 12dB/octave sounds better.
I usually cross over a dome or ribbon high when using a vintage cone tweeter and woofer as it preserves as much of the drivers original sound as possible while allowing the upper treble that most cone tweeters don't reproduce well to be properly reproduced.
Hadn't thought of that, however so far I haven't noticed any microphonics. I suppose maybe I could get some rubber bushings for the chassis to sit on which would help decouple the amp from the speaker.
Here's the crossover with the proper zobel values. Normally the drivers would be connected reverse polarity, however I had to build a one tube preamp that has a stage of gain and a cathode follower in order to have a real low impedance (eliminates miller capacitance issues with the first 12AX7 stage in the amp), make the stereo signal mono and step up the signal some given the phase splitter of the amp was redesigned for better operation and requires more signal. The Schiit Saga S preamp has a low enough impedance in active mode, but it has a gain of one.
The only thing I might do later on is look into building an open baffle subwoofer. The plan will be to make it a passive two way 12dB/octave crossover so that I do not need another amplifier which means the driver will need to be efficient. I'll make it to where the crossover has a 1/4" jack on the high pass output so that the speaker can plug into it. That way I can use the speaker with the sub or without the sub relatively easily. I'll need a good 15" 4 ohm driver that can handle at least 25 watts and I figure a 2' X 2' piece of wood like what I used for the speaker would be fine. Will likely use 70Hz for the crossover frequency. Will require a large inductor though along with larger value caps. Those will not be cheap as I will use film caps, however I do already have some larger value film caps from other projects I did in the past and later dismantled.
Concerning vibration and microphonics, if I use an open baffle sub that will likely reduce the vibration of the main speaker.
Here's the sources. I use one of those IR extenders for the preamp given it's in the closet. The nice thing is I can point the remote most anywhere in the room and the sensor of the extender picks it up, whereas without the extender I had to point the remote right at the preamp fairly precisely in order for it to work.
When it comes to high value caps. used in a low frequency sub. crossover, it is ok to use X quantity of 100V bipolar electrolytics +
a decent amount of higher quality film caps. in parallel, substantially reducing the cost. [ many say bipolar electro's are all that is needed for sub ]
@Tube Radio
I have an off-topic question >
What program are you using to present your circuit diagrams? They look good > is it free and does it include semiconductors?
PS.
I'd be happy to hear recommendations from other people also 🙂
I have an off-topic question >
What program are you using to present your circuit diagrams? They look good > is it free and does it include semiconductors?
PS.
I'd be happy to hear recommendations from other people also 🙂
I draw them up in Microsoft Paint. The symbols I use I find online using a Google search.
Also I decided to move the speaker and got better bass response so I will not need a sub or a larger baffle.
Also I decided to move the speaker and got better bass response so I will not need a sub or a larger baffle.