CLS said:How about hearing and feeling it?
You may even urge someone else (near you) to do it, and just have a listen when he/she's done. If you really don't want to do it yourself.
The guy might not even enjoy listening to music, have you considered that?? This is just a place to talk maths for him, which is fair enough, but it's not my cup of tea!
Hi,
I'm not looking for an argument.
I've been interested in building systems that play music
well (as opposed to being "hi-fi") for thirty years or so.
There is a lot I could say but its is simply not worth
the aggrevation (and misunderstanding of purpose)
that it would receive in this thread.
I prefer explanations that make sense to claims.
I like to understand what is in fact going on.
If your attitude is more empirical fair enough, but do
not knock mine. All good ideas stand on their own feet.
/sreten.
I'm not looking for an argument.
I've been interested in building systems that play music
well (as opposed to being "hi-fi") for thirty years or so.
There is a lot I could say but its is simply not worth
the aggrevation (and misunderstanding of purpose)
that it would receive in this thread.
I prefer explanations that make sense to claims.
I like to understand what is in fact going on.
If your attitude is more empirical fair enough, but do
not knock mine. All good ideas stand on their own feet.
/sreten.
Streten,
Sometimes your posts are interesting and/or helpful, but I can't understand your attitude towards others. I think you can come across as arrogant because you mock an idea that has worked very well for all its (vocal) users to date. I've noticed in other threads too, you can labour one technical point as if it's the only thing that matters, even when someone is happy with the benefits of a given approach. I do not wish to argue with you and happily accept that in your 30 years you've accumulated much more experience and knowledge than I could have in a much lesser time. With that said it would be nice if you could put your knowledge and experience to good use, by assisting others rather than seemingly looking for negatives in every thread you enter.
Please don't take this post as a personal attack, it's just a friendly suggestion based on my observations.
Simon
Sometimes your posts are interesting and/or helpful, but I can't understand your attitude towards others. I think you can come across as arrogant because you mock an idea that has worked very well for all its (vocal) users to date. I've noticed in other threads too, you can labour one technical point as if it's the only thing that matters, even when someone is happy with the benefits of a given approach. I do not wish to argue with you and happily accept that in your 30 years you've accumulated much more experience and knowledge than I could have in a much lesser time. With that said it would be nice if you could put your knowledge and experience to good use, by assisting others rather than seemingly looking for negatives in every thread you enter.
Please don't take this post as a personal attack, it's just a friendly suggestion based on my observations.
Simon
SimontY said:
Hi,
I don't.
My observations though are that for the fraction of threads that
the above appears to be the case there is a tacit assumption
that I'm being negative rather than it is an alternative viewpoint.
Once that starts it usually does not go anywhere sensible.
Perhaps for these cases I should just give up more often than not.
/sreten.I don't mind seeing some negative opinions, but I'd not be confused between them and my own experiences. Now I'm more than happy to have T-bass with my OB speakers, if someone tell me it is wrong, then, well, so be it. I mean, I'm not accepting I'm wrong (or who else is wrong), but accepting the fact that people can have different point of view.
In the end, I think people who love audio and diy can enjoy themselves well enough by common sense and passion. Common sense makes one educate him/her-self and helps on finding the right ways. Passion provides the motivation.
We all have common sense at least, don't we? And we all love audio and diy. What else do we need for communicating and sharing things here?
I do appreciate A LOT that there are so many pioneers here in diyaudio.com, sharing their precious experiences and knowledge. It's already a privilege to have so many supports here. I know I can not be a pioneer myself. Being a follower, learning things around, having new findings on the way, making something new and enjoyable, sharing all these... etc are SO GOOD, already. I'm grateful.
-------------
Back to the T-bass, I'd like to share some experiences in tuning the part's values.
Decreasing the C makes the boost start higher up, also move up the cut. While boost and cut occur higher, the boost on low down seems not increased all the way, but reach a 'plateau' earlier (higher in frequency). So this would increase output of midbass relatively.
Increasing the series R with C elevates the whole thing in gain and makes it somewhat broader and flatter. Again, increase in midbass would be more pronounced.
So if less midbass output and relatively more lower-end are desired, try increasing the C. But this would also decrease the overall available gain (can be brought back by some more series R). Overdoing this would yield a low gain and flat curve. This might also sound good, but a waste of drive current -- consumed around Zc and transformer, but not squeezed into woofer.
I haven't changed the value of choke yet, so nothing to say. (I guess enlarging the L should push both the cut and boost lower in frequency.) Increasing the series R makes the boost flatter and broader. Simply put, not so 'exciting'.
Descriptions above are my own observations on listening tests, impedance scans, and RTA readings, nothing fancy. If anything wrong, please correct me.
Meantime, within some extent, I found additional EQ works OK (or maybe quite well) with T-bass. Here EQ includes all kinds of filters, especially LP or notch for bass. During the process of my recent tunings on T-bass, more or less I need EQ for helping on leveling things, almost all the time.
In my latest setup on T-bass, L is 4.2mH without R, C is 800uF with 2.2R. And my upstream active xover was set f3=80Hz / 1st order LP; HP section is the same 1st order and has been fixed at 160Hz, which is also the acoustical xover point (maybe not very precise, but more or less around here). In this 80Hz LP setting, the midbass output was still too much. I needed about -4dB ~ -6dB of EQ adjustments in the 50~100Hz rang to suppress the boom.
So, I also tried lowering the LP section by an octave to 40Hz. This pretty much eliminated the requirements of EQ. In the end, frequency responses of both settings were nearly identical by RTA readings, and also very similar by ears. So alike they were, but I preferred the 40Hz LP without EQ version. It sounded cleaner to my ears. (maybe the acoustic phase responses were different)
I think to myself, the ideal situation should be: LP the bass section right at the acoustical xover point ¡V 160Hz, and then tuning the response by T-bass. I¡¦m not able to achieve that, yet. I imagine that¡¦d be very difficult. Like Graham once mentioned, the slope of compensation is important. After all, many things to be done here: cutting the dipole peak, compensating the baffle loss, and counteracting the driver¡¦s own response which is not so good¡Ketc. There might be 15~20dB of variation across only a few octaves here. It¡¦s so crowded and busy.
Now the bass seems work like this: cutting part is mostly done by active xover (40Hz LP), and the low down is boosted by T-bass. It¡¦s now working pretty well to my ears, very much improved compared to the previous system (already mentioned many times). However this must still be less than ideal. I can¡¦t imagine how good it can be, if fully ¡§tuned¡¨ by T-bass.
In the end, I think people who love audio and diy can enjoy themselves well enough by common sense and passion. Common sense makes one educate him/her-self and helps on finding the right ways. Passion provides the motivation.
We all have common sense at least, don't we? And we all love audio and diy. What else do we need for communicating and sharing things here?
I do appreciate A LOT that there are so many pioneers here in diyaudio.com, sharing their precious experiences and knowledge. It's already a privilege to have so many supports here. I know I can not be a pioneer myself. Being a follower, learning things around, having new findings on the way, making something new and enjoyable, sharing all these... etc are SO GOOD, already. I'm grateful.
-------------
Back to the T-bass, I'd like to share some experiences in tuning the part's values.
Decreasing the C makes the boost start higher up, also move up the cut. While boost and cut occur higher, the boost on low down seems not increased all the way, but reach a 'plateau' earlier (higher in frequency). So this would increase output of midbass relatively.
Increasing the series R with C elevates the whole thing in gain and makes it somewhat broader and flatter. Again, increase in midbass would be more pronounced.
So if less midbass output and relatively more lower-end are desired, try increasing the C. But this would also decrease the overall available gain (can be brought back by some more series R). Overdoing this would yield a low gain and flat curve. This might also sound good, but a waste of drive current -- consumed around Zc and transformer, but not squeezed into woofer.
I haven't changed the value of choke yet, so nothing to say. (I guess enlarging the L should push both the cut and boost lower in frequency.) Increasing the series R makes the boost flatter and broader. Simply put, not so 'exciting'.
Descriptions above are my own observations on listening tests, impedance scans, and RTA readings, nothing fancy. If anything wrong, please correct me.
Meantime, within some extent, I found additional EQ works OK (or maybe quite well) with T-bass. Here EQ includes all kinds of filters, especially LP or notch for bass. During the process of my recent tunings on T-bass, more or less I need EQ for helping on leveling things, almost all the time.
In my latest setup on T-bass, L is 4.2mH without R, C is 800uF with 2.2R. And my upstream active xover was set f3=80Hz / 1st order LP; HP section is the same 1st order and has been fixed at 160Hz, which is also the acoustical xover point (maybe not very precise, but more or less around here). In this 80Hz LP setting, the midbass output was still too much. I needed about -4dB ~ -6dB of EQ adjustments in the 50~100Hz rang to suppress the boom.
So, I also tried lowering the LP section by an octave to 40Hz. This pretty much eliminated the requirements of EQ. In the end, frequency responses of both settings were nearly identical by RTA readings, and also very similar by ears. So alike they were, but I preferred the 40Hz LP without EQ version. It sounded cleaner to my ears. (maybe the acoustic phase responses were different)
I think to myself, the ideal situation should be: LP the bass section right at the acoustical xover point ¡V 160Hz, and then tuning the response by T-bass. I¡¦m not able to achieve that, yet. I imagine that¡¦d be very difficult. Like Graham once mentioned, the slope of compensation is important. After all, many things to be done here: cutting the dipole peak, compensating the baffle loss, and counteracting the driver¡¦s own response which is not so good¡Ketc. There might be 15~20dB of variation across only a few octaves here. It¡¦s so crowded and busy.
Now the bass seems work like this: cutting part is mostly done by active xover (40Hz LP), and the low down is boosted by T-bass. It¡¦s now working pretty well to my ears, very much improved compared to the previous system (already mentioned many times). However this must still be less than ideal. I can¡¦t imagine how good it can be, if fully ¡§tuned¡¨ by T-bass.
There appears to be some fuss at the moment. I don't know what it is, and thus I am not distracted from the core of this thread. I have enough problems of my own to cope with without unproductive man-made friction.
http://uk.youtube.com/watch?v=iG9CE55wbtY&feature=channel_page
Hi BZ,
Christmas means I'm doing other things at the moment, but some aspects of your questions were answered in my replies to CLS, and as CLS has pointed out, there is much to this circuit which can be appreciated only when you actually run it.
Explicit crossover ?
Well surely this must depend upon the choice of driver. Some woofers start to cut off at little around 150Hz, some still have increasing response way beyond 1.5kHz.
The huge peaks of drivers can be dealt with mechanically, as per reversing the driver to reduce the cone's forward focussing effect, also by bra-strap mounted damping material on the voice coil axis.
Don't expect the electronics to be able to cure unwanted mechanically induced peaks and room corner reflections, these act in different time frames (dynamics).
T-bass is a useful circuit, but cannot do everything for all drivers, in all situations, and what any individual says works well for them in THEIR situation will not necessarily work well for everyone else.
How I blend mids - yes shallow if I can, with a simple C with damping R across the driver, or Q limited notch at Fs across the driver. Provides a well damped simple phase/slope to be matched by LF phase/slope, but again depends upon individual drivers.
Of course you can use LR4 if you wish, but I find a simple crossover less intrusive upon reproduction. This especially being where the T-bass has advantage because the LF remains integrated for small OB reproduction, better than I have heard before unless using something like say a full-range 12" driver on a large baffle, which of course simply cannot go as loud.
You say that you get huge peaks in the mids and a dipole peak around 250Hz. This clearly is not the best starting point for any dipole, and needs to be tackled before you go any further. OB woofers need to be large diameter, but don't need much enclosure depth. You might need to reflect rear waves along walls to prevent the development of reflective peaks. Try reversing your LF driver(s) and aim it into centrally positioned cushions in the corner.
Hi CLS.
Good to read your 'tuning' experiences.
Clearly you too understand why it is not possible to answer purely theoretically based questions about this circuit, for all aspects interact and the optimisation must be completed on a 'per use' basis.
A level balancing act must be performed which must be optimised for driver/room/baffle, but the woofer still needs to be suitable to start with in order to not require considerable EQ/LP which cannot sound right when used alone - different time frames for original waveforms and those which develop due to driver storage characteristics. You can however judiciously use some EQ ahead of the T-bass due to the way it reduces driver energy storage, and you will likely end up with a reasonably 'flat' system capable of good dynamics LF integrity. I though, prefer to run with non EQ drive, even if this means losing out on ultimate bandwidth extension.
Increasing the value of the choke will give a slight 'stretching' of the T-bass characteristic. It sets the low lift reference against which the unwanted mid-high bass level can be lowered to optimise the dynamic response.
Another aspect of course if loudness, for reproduction can be optimised for one level only. At lower listening levels the bass will be weak unless a loudness compensation or 'tone' controls are used.
Cheers ......... Graham.
http://uk.youtube.com/watch?v=iG9CE55wbtY&feature=channel_page
Hi BZ,
Christmas means I'm doing other things at the moment, but some aspects of your questions were answered in my replies to CLS, and as CLS has pointed out, there is much to this circuit which can be appreciated only when you actually run it.
Explicit crossover ?
Well surely this must depend upon the choice of driver. Some woofers start to cut off at little around 150Hz, some still have increasing response way beyond 1.5kHz.
The huge peaks of drivers can be dealt with mechanically, as per reversing the driver to reduce the cone's forward focussing effect, also by bra-strap mounted damping material on the voice coil axis.
Don't expect the electronics to be able to cure unwanted mechanically induced peaks and room corner reflections, these act in different time frames (dynamics).
T-bass is a useful circuit, but cannot do everything for all drivers, in all situations, and what any individual says works well for them in THEIR situation will not necessarily work well for everyone else.
How I blend mids - yes shallow if I can, with a simple C with damping R across the driver, or Q limited notch at Fs across the driver. Provides a well damped simple phase/slope to be matched by LF phase/slope, but again depends upon individual drivers.
Of course you can use LR4 if you wish, but I find a simple crossover less intrusive upon reproduction. This especially being where the T-bass has advantage because the LF remains integrated for small OB reproduction, better than I have heard before unless using something like say a full-range 12" driver on a large baffle, which of course simply cannot go as loud.
You say that you get huge peaks in the mids and a dipole peak around 250Hz. This clearly is not the best starting point for any dipole, and needs to be tackled before you go any further. OB woofers need to be large diameter, but don't need much enclosure depth. You might need to reflect rear waves along walls to prevent the development of reflective peaks. Try reversing your LF driver(s) and aim it into centrally positioned cushions in the corner.
Hi CLS.
Good to read your 'tuning' experiences.
Clearly you too understand why it is not possible to answer purely theoretically based questions about this circuit, for all aspects interact and the optimisation must be completed on a 'per use' basis.
A level balancing act must be performed which must be optimised for driver/room/baffle, but the woofer still needs to be suitable to start with in order to not require considerable EQ/LP which cannot sound right when used alone - different time frames for original waveforms and those which develop due to driver storage characteristics. You can however judiciously use some EQ ahead of the T-bass due to the way it reduces driver energy storage, and you will likely end up with a reasonably 'flat' system capable of good dynamics LF integrity. I though, prefer to run with non EQ drive, even if this means losing out on ultimate bandwidth extension.
Increasing the value of the choke will give a slight 'stretching' of the T-bass characteristic. It sets the low lift reference against which the unwanted mid-high bass level can be lowered to optimise the dynamic response.
Another aspect of course if loudness, for reproduction can be optimised for one level only. At lower listening levels the bass will be weak unless a loudness compensation or 'tone' controls are used.
Cheers ......... Graham.
Graham Maynard said:
Sure.
My system has always been optimised for low level listening. I've mentioned I'm a bass freak. Yes, I go for bass all the time but not SPL
In this regard, I think it's harder to get right. I like it gentle but firm, punchy but quietly, detailed but effortlessly. And T-bass helps a lot in these requirements
Graham,
Happy new year and thank you, Sir, for sharing this great idea with us all !
I did it a try - and was not dissapointed, quite on the contrary.
The T-bass circuit has replaced the active shelving low pass circuit on my 1 per channel Aplha 15A. To my first suprise, T-bass managed to EXCEED the low frequency extension of the around 8-9 dB equalization at about 30 Hz ! This was shown by ARTA measurements during set up of the circuit.
For now, I had to let the active LR4 crossoverin place just as before. The second surprise was the sound: clean low bass ! I had no chance to listen very much by now, but I have actually noticed that my current version of the circuit (it's very close to your original schematic, but no Zobel/notch after the transformer) seems to cut too much from the 100Hz bass: I will try to increase the R in series with the capacitor(680uF) to some 4.7 ohm (currently 2.2 ohm ) to get some midbass back.
Another interesting thing that still puzzles me is that apparently the excursion on the Alphas has been reduced(!) - in spite of the response being well extended ! Previously I was able to see the Alphas moving quite stressed at very low bass and high volume: it might be just an impression, but now the movement seems to be more controlled ! This might just be due to better control below the Fs - or again just my impression.
Next steps would be to play with replacing the LR4 crossover with something shallower: I do have the feeling that the integration with the midbass could be smoother.
For now, I am using 2 different transformers for the 2 channels: 200VA 2x29V and 150VA 2x18V. Measurements have not shown any significant differences in response, but I might want to buy another 200VA for symmetry.
Thanks again for this great idea !
Happy new year and thank you, Sir, for sharing this great idea with us all !
I did it a try - and was not dissapointed, quite on the contrary.
The T-bass circuit has replaced the active shelving low pass circuit on my 1 per channel Aplha 15A. To my first suprise, T-bass managed to EXCEED the low frequency extension of the around 8-9 dB equalization at about 30 Hz ! This was shown by ARTA measurements during set up of the circuit.
For now, I had to let the active LR4 crossoverin place just as before. The second surprise was the sound: clean low bass ! I had no chance to listen very much by now, but I have actually noticed that my current version of the circuit (it's very close to your original schematic, but no Zobel/notch after the transformer) seems to cut too much from the 100Hz bass: I will try to increase the R in series with the capacitor(680uF) to some 4.7 ohm (currently 2.2 ohm ) to get some midbass back.
Another interesting thing that still puzzles me is that apparently the excursion on the Alphas has been reduced(!) - in spite of the response being well extended ! Previously I was able to see the Alphas moving quite stressed at very low bass and high volume: it might be just an impression, but now the movement seems to be more controlled ! This might just be due to better control below the Fs - or again just my impression.
Next steps would be to play with replacing the LR4 crossover with something shallower: I do have the feeling that the integration with the midbass could be smoother.
For now, I am using 2 different transformers for the 2 channels: 200VA 2x29V and 150VA 2x18V. Measurements have not shown any significant differences in response, but I might want to buy another 200VA for symmetry.
Thanks again for this great idea !
Hi BZ,
Yes Happy New Year, then let's hope we can start to see the making of a better future, and if not for everyday life then at least for audio.
I'm so pleased you find the circuit to be worthwhile, it gives us back what has been missing for so long, maybe with the increase in LF SPL being greater with higher Qes drivers. I often comment that low Qes drivers are more accurate, but all drivers can be improved when the leading edge impulse compensate for driver weakness. The T-bass circuit has capability to spare in this regard no matter what the driver Qes.
Unfortunately transformers now cost so much, but the natural nature of reproduction cannot be acheived any other way no matter how powerful an amp or how large a driver.
I wish you luck in fine tuning your combination, and don't forget that something like a large fluffy paint roller mounted in front of the Alpha can act like an extra MF filter as it reduces axial beaming.
Re the apparently decreased cone excursion - when the reproduction is more correct at all frequencies it does not need to be louder at some in order to compensate.
Cheers ...... Graham.
Yes Happy New Year, then let's hope we can start to see the making of a better future, and if not for everyday life then at least for audio.
I'm so pleased you find the circuit to be worthwhile, it gives us back what has been missing for so long, maybe with the increase in LF SPL being greater with higher Qes drivers. I often comment that low Qes drivers are more accurate, but all drivers can be improved when the leading edge impulse compensate for driver weakness. The T-bass circuit has capability to spare in this regard no matter what the driver Qes.
Unfortunately transformers now cost so much, but the natural nature of reproduction cannot be acheived any other way no matter how powerful an amp or how large a driver.
I wish you luck in fine tuning your combination, and don't forget that something like a large fluffy paint roller mounted in front of the Alpha can act like an extra MF filter as it reduces axial beaming.
Re the apparently decreased cone excursion - when the reproduction is more correct at all frequencies it does not need to be louder at some in order to compensate.
Cheers ...... Graham.
So I tried T-bass on my Beta15s with the component values I had (44v secondaries instead of 18-40, 10mh instead of 6.4, and 470uf instead of 940uF). WOW, pretty much as Graham described, evening out the dipole roll-off but with more ‘punch.’ Stand-up bass has more texture and drums have more impact—sweet!
Just for fun I ran the Beta15s full open all the way up to ~2k and topped it off with some KSN1188s I have lying around. Hmm, not bad! I did a quick measurement with my Ultracurve + ECM8000 mic and noticed that the 1.6k peak was still there. The notch missed a bit and was centered at 1k with the 1.6k peak still prominent.
I played with some sims in Ucap and changed the 10uF cap in the 1.6k notch filter to 2.8uF and that killed the peak more effectively both in sim and measurement. Wow, I couldn’t believe I was getting such good sound going through a transformer and huge coils!
Just for laughs I tried using my simple gainclone—not as much impact as my bigger amp but as long as the volume’s not too loud, not bad! Then for giggles, I tried my 1.5 Decware Zen tube amp—again not as much impact but more bass than I’ve ever gotten out of the little beast! I may try to make a T-bass system based on it for my basement room.
I’m now trying some different tops for the Beta15s; Audax PR170MO, Fostex FE164, Eminence Beta12LT, FE103, FE83 … we’ll see which one sounds best. I’m noticing a big shelf below 400Hz on all of them (baffle step on a 16” baffle?!?) so I may try to crossover there.
I’m sold on the T-bass! I may try fancy DSP later but for now this is where it’s at! So what’s the process for tweaking the T-bass circuit? Would you suggest free air or in-room/listening position measurements? How do you model the transformer (I can’t seem to find transformers in parts list for Ucap)? Are they just two massive coils? Which parts to upgrade/change first?
Looking forward to making this even better!
Cheers and thanks for the help,
Jeff
Just for fun I ran the Beta15s full open all the way up to ~2k and topped it off with some KSN1188s I have lying around. Hmm, not bad! I did a quick measurement with my Ultracurve + ECM8000 mic and noticed that the 1.6k peak was still there. The notch missed a bit and was centered at 1k with the 1.6k peak still prominent.
I played with some sims in Ucap and changed the 10uF cap in the 1.6k notch filter to 2.8uF and that killed the peak more effectively both in sim and measurement. Wow, I couldn’t believe I was getting such good sound going through a transformer and huge coils!
Just for laughs I tried using my simple gainclone—not as much impact as my bigger amp but as long as the volume’s not too loud, not bad! Then for giggles, I tried my 1.5 Decware Zen tube amp—again not as much impact but more bass than I’ve ever gotten out of the little beast! I may try to make a T-bass system based on it for my basement room.
I’m now trying some different tops for the Beta15s; Audax PR170MO, Fostex FE164, Eminence Beta12LT, FE103, FE83 … we’ll see which one sounds best. I’m noticing a big shelf below 400Hz on all of them (baffle step on a 16” baffle?!?) so I may try to crossover there.
I’m sold on the T-bass! I may try fancy DSP later but for now this is where it’s at! So what’s the process for tweaking the T-bass circuit? Would you suggest free air or in-room/listening position measurements? How do you model the transformer (I can’t seem to find transformers in parts list for Ucap)? Are they just two massive coils? Which parts to upgrade/change first?
Looking forward to making this even better!
Cheers and thanks for the help,
Jeff
Graham Maynard said:
I have changed the C series resistor to 4.7 and indeed I got the missing balance back(s. below) - after some more listening I can tell that this is definitely the best bass I have ever heard from my system !
The change is also definitely a qualitative one: I have now pretty much the same frequency response as before, but it sounds so much different !
So in my case:
- Alpha 15A mounted in shallow Y-dipoles(depth about 25 cm, largish rear opening - close to U)
- C=680uf, series R=4.7 ohm
- L=Intertechnik ferrite 6.8mH, 0.26 Ohm, series R=1 ohm
- trafos:2x29V 200VA
Here's a frequency response measurement in room - measured in the middle of the room, you can also see the difference between 2.2(dark) and 4.7(lighter) resistors:
Attachments
bzfcocon said:
and isn't this exactly what I have been saying for so long.
The frequency response tells you nothing about the reproduction -
this because the steady sine response arises after all changes have passed and settled down to a measurable level.
Steady amplitude measurements tell you nothing about the coherence of dynamic amplitude , phase and thus timing responses which are so relevent within music reproduction !
Those who don't hear this difference simply cannot appreciate it !
( Horse - water ? )
Nor am I trying to be big headed here either, because I had been as taken in as everyone else by all of the text book write-ups about how to 'do' bass reproduction - the proven ways of getting 'best' bass from a particular cabinet volume etc. !
Cheers ....... Graham.
PS. My monitor does not show any lines on your response chart.
Oh, where to start?
I started in OB and hifi about 6 months ago due to the DarkStar thread and have not looked back since. Well, almost. I love the open and effortless sound I'm getting but have tried not to be discontent with the bass from my single alnico 12" Coaxials in modified JE Labs baffles (24").
Enter TBass. Thank you Graham for sharing this. I have followed your posts on this subject from the beginning with great interest. I haven't implemented the circuit yet but I am working on getting the parts together. Today I bought an amp capable of handling 2ohm loads with damping factor of >300 @ 8ohms. Soon I will buy the toroids and inductors(expensive stuff!!).
My QuandaryIf this is inappropriate I'll delete this post but since it builds on Graham's circuit I thought it might be OK)
I will plan on using my 12" Coax or my soon to be arriving 12" Coral Triaxials in a small OB down to 100Hz or so. The problem is what to use for the bass support with Graham's TBass. Here is what I have and I would really appreciate any help and advice. 2 each of Coral 12" ceramic magnet woofers, Qts .6 inverted roll surround, about 93db. 2 each 15" coral ceramic woofers, Qts unknown, efficiency unknown but very similar in build to the 12"s. 4 Goldwood 18" woofers, Qts 1, 93db, Fs 30.
The plan? I would like to use my PP 8wpc tube amp to run the Coral FRs (~95db) magnet mounted and the SS amp to run the bass with a DBX active XO(MJK copycat) to divide things.
So, should I use a completely separate and isolated baffle for the 12" FRs? Should I try to use the two disparate pairs of Coral woofers(4 woofers total on baffles)? Or should I pull out all the stops and use all four of the Goldwood 18"s? Then what baffle alignment to use? W frame for the goldwoods or flat baffle(Grahams choice)? I'm open to ideas, I'm just chomping at the bit to implement the TBass after all I have read of it. And I've got a full sheet of 3/4" Birch, double sanded, sitting in my shop waiting to be used.
I really wanted to keep this thread active as I have learned so much from all the contributors. Thank you all so much.
Erik
I started in OB and hifi about 6 months ago due to the DarkStar thread and have not looked back since. Well, almost. I love the open and effortless sound I'm getting but have tried not to be discontent with the bass from my single alnico 12" Coaxials in modified JE Labs baffles (24").
Enter TBass. Thank you Graham for sharing this. I have followed your posts on this subject from the beginning with great interest. I haven't implemented the circuit yet but I am working on getting the parts together. Today I bought an amp capable of handling 2ohm loads with damping factor of >300 @ 8ohms. Soon I will buy the toroids and inductors(expensive stuff!!).
My Quandary
If this is inappropriate I'll delete this post but since it builds on Graham's circuit I thought it might be OK)I will plan on using my 12" Coax or my soon to be arriving 12" Coral Triaxials in a small OB down to 100Hz or so. The problem is what to use for the bass support with Graham's TBass. Here is what I have and I would really appreciate any help and advice. 2 each of Coral 12" ceramic magnet woofers, Qts .6 inverted roll surround, about 93db. 2 each 15" coral ceramic woofers, Qts unknown, efficiency unknown but very similar in build to the 12"s. 4 Goldwood 18" woofers, Qts 1, 93db, Fs 30.
The plan? I would like to use my PP 8wpc tube amp to run the Coral FRs (~95db) magnet mounted and the SS amp to run the bass with a DBX active XO(MJK copycat) to divide things.
So, should I use a completely separate and isolated baffle for the 12" FRs? Should I try to use the two disparate pairs of Coral woofers(4 woofers total on baffles)? Or should I pull out all the stops and use all four of the Goldwood 18"s? Then what baffle alignment to use? W frame for the goldwoods or flat baffle(Grahams choice)? I'm open to ideas, I'm just chomping at the bit to implement the TBass after all I have read of it. And I've got a full sheet of 3/4" Birch, double sanded, sitting in my shop waiting to be used.
I really wanted to keep this thread active as I have learned so much from all the contributors. Thank you all so much.
Erik
Hi Simon,
Thanks for the reply. Well, I would say that space isn't an issue as long as I build them with castors so that they could be rolled into the back room when not listening. In fact, that would pretty much be true with everything. Not because of WAF but because of some pint sized people who get a bit wild around the house. As it is now I carry everything back and forth, except for my amps, which I put on a piano dolly which rolls rather nicely. It is a cumbersome task to repeat almost daily though.
I don't doubt that the 4 18"s would be up to the task, but perhaps I could be satisfied with a combination of the 12"s and 15"s? Only I would know, I guess. I've got a lot of sand amp here now that I made a good score off of Craigslist.org. I know that the Qts and Qes of the Goldwoods are rather high according to Mr. Maynards ideals for his circuit. Still not sure. I am quite willing to learn from the experience here. And would the 18's be able to 'hand off' to the 12's as he says? Perhaps an incremental approach, starting off slowly with a small 18" baffle, the Corals 12"s on top and the 15"s under them. It might make for an interesting development. All part of the path.
I might say, as an aside, that I am using an active xo simply becuase I am a bit intimidated by passive xo's and what seems to be quite an involved process to integrate slopes, drivers, etc. Perhaps one day, with a bit of reading and research...
Erik
Thanks for the reply. Well, I would say that space isn't an issue as long as I build them with castors so that they could be rolled into the back room when not listening. In fact, that would pretty much be true with everything. Not because of WAF but because of some pint sized people who get a bit wild around the house. As it is now I carry everything back and forth, except for my amps, which I put on a piano dolly which rolls rather nicely. It is a cumbersome task to repeat almost daily though.
I don't doubt that the 4 18"s would be up to the task, but perhaps I could be satisfied with a combination of the 12"s and 15"s? Only I would know, I guess. I've got a lot of sand amp here now that I made a good score off of Craigslist.org. I know that the Qts and Qes of the Goldwoods are rather high according to Mr. Maynards ideals for his circuit. Still not sure. I am quite willing to learn from the experience here. And would the 18's be able to 'hand off' to the 12's as he says? Perhaps an incremental approach, starting off slowly with a small 18" baffle, the Corals 12"s on top and the 15"s under them. It might make for an interesting development. All part of the path.
I might say, as an aside, that I am using an active xo simply becuase I am a bit intimidated by passive xo's and what seems to be quite an involved process to integrate slopes, drivers, etc. Perhaps one day, with a bit of reading and research...
Erik
I get by just fine with 4 x 7" woofers per side in a tiny room. From what I've experienced a 12" and 15" playing together should do some wonderful things.
How much displacement you really need depends on various factors, such as:
* Expectations and preferences
* How much EQ is used
* SPL typically used
* Distance from listener to speakers
* Music type typically played
* To a tiny extent watts on tap
* Overkill and headroom desired
If you want the bass to physically shake you, I can say that the displacement I have on offer with my current speakers is insufficient. I'm doing 2 x 12" per side next and will be sure to report here (500VA transformers for T-bass).
I can also make an educated guess that if using the Goldwoods you'll need very little EQ, and would be using the T-bass purely as icing on the cake.
You need also to consider that what may work for Graham might be overkill in your home or not your cup of coffee.
One thing is for certain here: T-bass can make a very large audible difference (so far everyone's saying improvement only) and change to measured response (EQ - less relevant as it doesn't correlate to sound quality very well in my measurements).
I'm sure Graham would love to add to what I've said as I have only limited experience with this type of speaker, and all speakers!
BTW, active could and should be a positive thing, so don't be so keen on going passive - not in a 2-way crossed over in the bass range.
Simon
How much displacement you really need depends on various factors, such as:
* Expectations and preferences
* How much EQ is used
* SPL typically used
* Distance from listener to speakers
* Music type typically played
* To a tiny extent watts on tap
* Overkill and headroom desired
If you want the bass to physically shake you, I can say that the displacement I have on offer with my current speakers is insufficient. I'm doing 2 x 12" per side next and will be sure to report here (500VA transformers for T-bass).
I can also make an educated guess that if using the Goldwoods you'll need very little EQ, and would be using the T-bass purely as icing on the cake.
You need also to consider that what may work for Graham might be overkill in your home or not your cup of coffee.
One thing is for certain here: T-bass can make a very large audible difference (so far everyone's saying improvement only) and change to measured response (EQ - less relevant as it doesn't correlate to sound quality very well in my measurements).
I'm sure Graham would love to add to what I've said as I have only limited experience with this type of speaker, and all speakers!
BTW, active could and should be a positive thing, so don't be so keen on going passive - not in a 2-way crossed over in the bass range.
Simon
Hi Simon,
Thanks for the advice, I'll try to respond to what you have said.
I have used quite a bit of digital EQ with iTunes, up to 10dB boost for the bass regions. Getting away from that would be a blessing.
I don't generally listen very loud, but then that depends on the mood and time of day.
If I am sitting to listen then I am about 6-8 feet away from the speakers. I find that the nice thing about OB is that you can be working in another room and the instruments sound very real and live. I like it.
I love to listen to Baroque, but then my tastes range all the way to Reggae(No rap for me please).
I would love to be able to capture the dynamics I witnessed at a friend's house with his just acquired Altec A7's. Truly amazing. So, I don't know about overkill but I would like to be able to reproduce the dynamics of a live concert. Perhaps a bit much to ask, but still...
Thanks for the comment about xo's. Makes me feel a bit more justified in my general ignorance on the subject.
Erik
Thanks for the advice, I'll try to respond to what you have said.
I have used quite a bit of digital EQ with iTunes, up to 10dB boost for the bass regions. Getting away from that would be a blessing.
I don't generally listen very loud, but then that depends on the mood and time of day.
If I am sitting to listen then I am about 6-8 feet away from the speakers. I find that the nice thing about OB is that you can be working in another room and the instruments sound very real and live. I like it.
I love to listen to Baroque, but then my tastes range all the way to Reggae(No rap for me please).
I would love to be able to capture the dynamics I witnessed at a friend's house with his just acquired Altec A7's. Truly amazing. So, I don't know about overkill but I would like to be able to reproduce the dynamics of a live concert. Perhaps a bit much to ask, but still...
Thanks for the comment about xo's. Makes me feel a bit more justified in my general ignorance on the subject.
Erik
From my own experience and from what Graham has said, losing that EQ in favour of T-bass will gain some dynamics and a new-found quality of bass. T-bass doesn't sound forced and bloated, it just makes deeper, louder, more articulated bass.. even when using the full 6dB of gain as I do.
I will be waiting to hear about it
Simon
I will be waiting to hear about it
Simon