Good question, but I have no answer yet. I will try it tonight (I'm at work right now) and let you know. It will be intersting to figure out what it is, and how to "cure" it.
Thanks
Hi Graham,
Tonight I played a bit more with some test tones, and tried to bypass the T-bass circuit to get the idea as to what is influencing what...
Without T-bass, I get less of everything below 70-80 Hz or so. I like the sound with T-bass more than without it. But, the frequency fluctuation remains similar. There is quite strong sound of 40 Hz. As the frequency is increased toward 50, it becomes quieter,and even more quiet at 60 Hz. ( and the speaker cone moves less).
Above that, it starts to rise and at 70-75 Hz comes to the (subjective) level of that 40 Hz tone. It is a very similar pattern even without T-bass, except that everything sounds weaker...
While I am aware that I may just be dealing with speaker and/or room resonance, I would like to use the T-bass circuit to lift the region of 45-65 hz so it will sound flatter..
I wouldn't like to use software EQ...
Thanks,
Vix
Tonight I played a bit more with some test tones, and tried to bypass the T-bass circuit to get the idea as to what is influencing what...
Without T-bass, I get less of everything below 70-80 Hz or so. I like the sound with T-bass more than without it. But, the frequency fluctuation remains similar. There is quite strong sound of 40 Hz. As the frequency is increased toward 50, it becomes quieter,and even more quiet at 60 Hz. ( and the speaker cone moves less).
Above that, it starts to rise and at 70-75 Hz comes to the (subjective) level of that 40 Hz tone. It is a very similar pattern even without T-bass, except that everything sounds weaker...
While I am aware that I may just be dealing with speaker and/or room resonance, I would like to use the T-bass circuit to lift the region of 45-65 hz so it will sound flatter..
I wouldn't like to use software EQ...
Thanks,
Vix
Hi Vix,
Once you T-bass balance out the dynamics of the LF driver you can give it some EQ and it will be just fine.
If you try with EQ alone it will sound much less natural.
Are your baffles too close into a corner ?
Try closer to a sidewall and further out from the corner.
Also if you are using T-bass plus a crossover, then the T-bass must be connected directly to the amplifier. T-bass cannot be driven by a crossover circuit.
Once you T-bass balance out the dynamics of the LF driver you can give it some EQ and it will be just fine.
If you try with EQ alone it will sound much less natural.
Are your baffles too close into a corner ?
Try closer to a sidewall and further out from the corner.
Also if you are using T-bass plus a crossover, then the T-bass must be connected directly to the amplifier. T-bass cannot be driven by a crossover circuit.
Thanks Graham,
No, baffles are not so close into the corners. T-bass is connected directly to the amplifier and the speaker on the other side. The crossover is active, 12 db/oct Linkwitz-Riley, cut at 120 Hz. I was against the EQ, because, when I enable the EQ on winamp, it does not sound as good...
No, baffles are not so close into the corners. T-bass is connected directly to the amplifier and the speaker on the other side. The crossover is active, 12 db/oct Linkwitz-Riley, cut at 120 Hz. I was against the EQ, because, when I enable the EQ on winamp, it does not sound as good...
Component values to avoid turntable rumble?
Hi Graham,
I've added a turntable to my T-bass system and I'm getting a bit of flutter from the cones at higher volumes.
It looks like about 5 Hz.
I'm using one Beta15 per side (2 per side later) and assembled the T-bass with the component values I had at hand (44v transformer secondaries instead of 18-40v, 10mh instead of 6.4mH, and 470uf instead of 940uF).
Now given that the Beta15 has a bit lower Fs than most pro 15s (Fs=35Hz, Re=6.3 ohm, Le=1.1mH) how should I adjust my T-bass circuit to minimize the turntable rumble? I'm thinking of ordering some 6.4mH (or whatever you suggest) inductors so that I'm starting from the preferred circuit.
Thanks,
Jeff
Hi Graham,
I've added a turntable to my T-bass system and I'm getting a bit of flutter from the cones at higher volumes.
It looks like about 5 Hz.I'm using one Beta15 per side (2 per side later) and assembled the T-bass with the component values I had at hand (44v transformer secondaries instead of 18-40v, 10mh instead of 6.4mH, and 470uf instead of 940uF).
Now given that the Beta15 has a bit lower Fs than most pro 15s (Fs=35Hz, Re=6.3 ohm, Le=1.1mH) how should I adjust my T-bass circuit to minimize the turntable rumble? I'm thinking of ordering some 6.4mH (or whatever you suggest) inductors so that I'm starting from the preferred circuit.
Thanks,
Jeff
Hi Jeff,
Hope you got sorted on that.
Sounds like your phono stage does not roll off as per RIAA. I once built a phono stage where the roll off was 25Hz instead of 50Hz, but it had additional high pass to cut steeply below 20Hz.
Hi Peter.
Are they different batches ? What about resistances ?
Have you tried powering them from the mains supply and measuring the voltages in case one is wrongly labelled.
Cheers ......... Graham.
Hope you got sorted on that.
Sounds like your phono stage does not roll off as per RIAA. I once built a phono stage where the roll off was 25Hz instead of 50Hz, but it had additional high pass to cut steeply below 20Hz.
Hi Peter.
Are they different batches ? What about resistances ?
Have you tried powering them from the mains supply and measuring the voltages in case one is wrongly labelled.
Cheers ......... Graham.
Hi Graham,
Serial number is the same. I was told that they have to produce these as Tipo, (manufacturer) does not keep them in stock.
I have not checked if they have correct voltage, only measuered inductance and resistance. Both have 0.2 Ohm
Logical question is, how can they have the same voltage if the inductance is ~66% off? If half of eastern europe have a shortage of power, you know who to blame....
Peter
Serial number is the same. I was told that they have to produce these as Tipo, (manufacturer) does not keep them in stock.
I have not checked if they have correct voltage, only measuered inductance and resistance. Both have 0.2 Ohm
Logical question is, how can they have the same voltage if the inductance is ~66% off? If half of eastern europe have a shortage of power, you know who to blame....
Peter
The tranformer in my previous post -- http://www.diyaudio.com/forums/full-range/130679-t-bass-drive-ob-lf-drivers-13.html#post1683582 is 110V / 28-0-28, 400VA. It has an inductance of 415.6 mH across the whole secondary.
I got another transformer with unkown spec (but physically bigger than the above), measured 170.2 mH across the winding I used.
I measured them with WT3 and no current through them except the tiny measuring current provided by USB interface which I don't how much.
Those 2 types of transformers above gave me excellent results.
I got another transformer with unkown spec (but physically bigger than the above), measured 170.2 mH across the winding I used.
I measured them with WT3 and no current through them except the tiny measuring current provided by USB interface which I don't how much.
Those 2 types of transformers above gave me excellent results.
Does this not suggest the transformers are not the same ?
For stereo they should be the same or you could have non original music signal induced differential LF components within the room.
Try this method: Film capacitor (C) of known value, range 10 - 50 uF in series with Inductor (L). Drive this with power amp, with a sweep generator at its input.
Attach a ac voltmeter over the capacitor, sweep the generator and look for a peak voltage. Write down the frequency (F) at this peak point and you have the inductance from:
L =((1/6.3xF)x(1/6.3xF))/C
You can use your computer as a sweep generator with this program.
Audio Tools - from David Taylor, Edinburgh
Attach a ac voltmeter over the capacitor, sweep the generator and look for a peak voltage. Write down the frequency (F) at this peak point and you have the inductance from:
L =((1/6.3xF)x(1/6.3xF))/C
You can use your computer as a sweep generator with this program.
Audio Tools - from David Taylor, Edinburgh
Well, something is wrong for sure.
That sentence went over my head, and ceiling also for that matter
@Jonas,
Thanks, I will try this method when I have more time. For now I will try to talk with the store I bought them in. Wish me luck, there are no guarantees for service minded people in stores here. Getting better, though have a long way to go.
Peter
