hi there,
I am currently working on a ATC SCM100A clone.
I've got everything sorted except tweeters.
I am torn between Seas T25CF001 (which ATC originally used in their line before they started making and using their own tweeters)
or a Seas 27TBCD/GB-DXT
(http://www.seas.no/images/stories/prestige/pdfdatasheet/H1499_27TBCD_GB-DXT_Datasheet.pdf)
The latter one has a waveguid and hence I expect better dispertion and I know this tweeter from Grimm and Kii Three speakers, which I both really like.
The T25CF001 however was originally used by ATC .. BUT it used ferrofluid!
I really don't like ferrofluid tweeters as the ferrofluid can dry out over the years and change its frequency-response.
So any suggestions?
Further I was wondering if anybody here has seen a original ATC SCM100Asl from the inside.
Since its a ported cabinet design I wouldn't know how to dampen the inside correctly.
Well I guess bitumen and/or eggfoam to all plain surfaces, for sure.
But then should I also fill the whole void with wool?
What do you suggest?
Thanks in advance
I am currently working on a ATC SCM100A clone.
I've got everything sorted except tweeters.
I am torn between Seas T25CF001 (which ATC originally used in their line before they started making and using their own tweeters)
or a Seas 27TBCD/GB-DXT
(http://www.seas.no/images/stories/prestige/pdfdatasheet/H1499_27TBCD_GB-DXT_Datasheet.pdf)
The latter one has a waveguid and hence I expect better dispertion and I know this tweeter from Grimm and Kii Three speakers, which I both really like.
The T25CF001 however was originally used by ATC .. BUT it used ferrofluid!
I really don't like ferrofluid tweeters as the ferrofluid can dry out over the years and change its frequency-response.
So any suggestions?
Further I was wondering if anybody here has seen a original ATC SCM100Asl from the inside.
Since its a ported cabinet design I wouldn't know how to dampen the inside correctly.
Well I guess bitumen and/or eggfoam to all plain surfaces, for sure.
But then should I also fill the whole void with wool?
What do you suggest?
Thanks in advance
I know you are building a clone but I just want to share abit of my experience.
After hearing various models various times, the mid is the real star of the show with the rest being incomparable co-stars.
I lived with both seas tweeters you ask about and found both to be uninteresting.
Two friends owns the ATC mid (non SL) and are now debating between Raal ribbon or SB Satori beryllium for highs and SB WO24 or MW19 for bass.
Since the mid also takes care of the off axis response transition between tweeter to a woofer you could technically use anything you wish for both highs and bass, go nuts, try all sorts of different parts. Being active makes this a cakewalk to do.
After hearing various models various times, the mid is the real star of the show with the rest being incomparable co-stars.
I lived with both seas tweeters you ask about and found both to be uninteresting.
Two friends owns the ATC mid (non SL) and are now debating between Raal ribbon or SB Satori beryllium for highs and SB WO24 or MW19 for bass.
Since the mid also takes care of the off axis response transition between tweeter to a woofer you could technically use anything you wish for both highs and bass, go nuts, try all sorts of different parts. Being active makes this a cakewalk to do.
Just for the record and to make things straight:
There is no SL ATC mid-dome.. its called just the S-versions which has a larger magnet than the non-S version..
I don't see a reason for SB Satori beryllium over ScanSpeak or Seas beryllium tweeters.
ScanSpeak and Seas just do the best tweeters in my opinion..
Besides super hi-end stuff like Accutone or RAAL of course 🙄
Hi Hugo, I don't subscribe to a philosophy that ferrofluid is anyhow bad, and I would not advise to worry about a potential ferrofluid failure since it may pass good 2-3 decades to develop as such. Don't worry about it, and if you still are not convinced, you can wipe the new ferrofluid out of the gap and voice coil if it'll bring you a peace of mind. I have worked with less expensive Seas KT28F which is a high quality performer so a classier excel can probably only excel on that one.
On the stuffing topic, stick to a universally good rule of good practice. Not overly dense, stuff the entire enclosure chamber with wool natural or poly and leave the space around woofer and vent free not to impede the airflow. This will kill the airborne resonances in the box. Bitumen pads may not be necessary but can't hurt things if you fancy having some. Can you upload some photos of this project of yours?
On the stuffing topic, stick to a universally good rule of good practice. Not overly dense, stuff the entire enclosure chamber with wool natural or poly and leave the space around woofer and vent free not to impede the airflow. This will kill the airborne resonances in the box. Bitumen pads may not be necessary but can't hurt things if you fancy having some. Can you upload some photos of this project of yours?
Thanks for your reply, I will upload some pictures as soon as the housing has been built.
But I am still hesistant wether to put the 12" ATC bass into a sealed 50L box (with DSP correction for bass response and phase) or build a SCM100 clone as close as possible.
Hence with a 100L ported housing just like the original ATC loudspeaker.
But I am not sure to what frequency I would tune a bass reflex housing.
And sealed cabinets are spoken to deliver a bass which is more accurate and dry over a BR box.. difficult decision since I am producing lots of bass heavy music
But I am still hesistant wether to put the 12" ATC bass into a sealed 50L box (with DSP correction for bass response and phase) or build a SCM100 clone as close as possible.
Hence with a 100L ported housing just like the original ATC loudspeaker.
But I am not sure to what frequency I would tune a bass reflex housing.
And sealed cabinets are spoken to deliver a bass which is more accurate and dry over a BR box.. difficult decision since I am producing lots of bass heavy music
I would base my decision on practical circumstances and what I wanted to achieve with this build. If you want to make a clone, then it's easy. Passive solution is practical for you cross your woofer higher to meet the midrange dome and by doing that you are far away from woofer impedance humps that cause headaches to passive crossover designers. I can help you decide to tune the woofer. Is there official specs for it?
I'm not a fan of sealed cabs but I do like high-passed ported ones.
Reason being that porting substantially reduces excursion and high excursion = high distortion. Porting increases headroom and decreases stresses on the driver.
Also not a fan of completely filling ported cabs with stuffing. Very much prefer just lining the cab with fairly dense damping material hoping to absorb most if not everything above 250Hz or so. I glue my lining in with a water-based, rubberized bitumen paint.
Don't use wool for a ported box or you will get moths. Been there tried that and inadvertently increased the moth population quite a bit. 🙂
Reason being that porting substantially reduces excursion and high excursion = high distortion. Porting increases headroom and decreases stresses on the driver.
Also not a fan of completely filling ported cabs with stuffing. Very much prefer just lining the cab with fairly dense damping material hoping to absorb most if not everything above 250Hz or so. I glue my lining in with a water-based, rubberized bitumen paint.
Don't use wool for a ported box or you will get moths. Been there tried that and inadvertently increased the moth population quite a bit. 🙂
With a dome midrange I woul choose a 3/4" tweeter, perhaps this one
H1280-06 22TFF
a 12" sealed bass would be my option. Sealed bass just sounds better and the speaker wants to sit near front wall. A br sould be tuned low, well below 40Hz to pass my QA. But it migt easily be too much of a room mode bomber...
H1280-06 22TFF
a 12" sealed bass would be my option. Sealed bass just sounds better and the speaker wants to sit near front wall. A br sould be tuned low, well below 40Hz to pass my QA. But it migt easily be too much of a room mode bomber...
Last edited:
@Lojzek : I forgot to mention but this build will be active either way.
I will use those new Hypex Fusion plate amps once they are out in april.
They include a DSP too, so I can phase and time align drivers and adjust their frequency response if needed and adjust to my room.
@Charles Darwin : Your points are fair regarding excursion and THD of ported vs. sealed boxes.
But fair enought to mention that sealed boxes have some advantages over ported cabinets too.. such as: tighter/faster bass response, smoother roll-of and no port-noises.
Also I am wondering if ported cabinets excite room modes quicker than sealed boxes??
@Juhazi : another good point here 🙂 I haven't totally forgotten about 3/4" .. since I will be crossing over at 3.5kHz this would definitlely work.
There is also Hiquphon tweeters which are spoken to be brilliant.
(Hiquphon 1st natural choice in 3/4" soft dome tweeters - 20mm soft dome tweeter type OWI, OWII, OW3, OW4 .... and more. Designed and produced in Denmark since 1983.)
If I will go with a BR housing, I'd stick to ATCs specs and use a 10cm diameter and 20cm long tube which would put a 100L cabinet to a tuning frequency of circa 29Hz.
Do you think that would work well or should I tune it even deeper to lets say 23Hz (Fs of the 12" ATC driver btw)
I am still torn
I will use those new Hypex Fusion plate amps once they are out in april.
They include a DSP too, so I can phase and time align drivers and adjust their frequency response if needed and adjust to my room.
@Charles Darwin : Your points are fair regarding excursion and THD of ported vs. sealed boxes.
But fair enought to mention that sealed boxes have some advantages over ported cabinets too.. such as: tighter/faster bass response, smoother roll-of and no port-noises.
Also I am wondering if ported cabinets excite room modes quicker than sealed boxes??
@Juhazi : another good point here 🙂 I haven't totally forgotten about 3/4" .. since I will be crossing over at 3.5kHz this would definitlely work.
There is also Hiquphon tweeters which are spoken to be brilliant.
(Hiquphon 1st natural choice in 3/4" soft dome tweeters - 20mm soft dome tweeter type OWI, OWII, OW3, OW4 .... and more. Designed and produced in Denmark since 1983.)
If I will go with a BR housing, I'd stick to ATCs specs and use a 10cm diameter and 20cm long tube which would put a 100L cabinet to a tuning frequency of circa 29Hz.
Do you think that would work well or should I tune it even deeper to lets say 23Hz (Fs of the 12" ATC driver btw)
I am still torn
hugo agreed.
It is all a compromise, I'm just stating where my preference lies.
Those Fusion amps look very interesting (at last!), let us know what you think of them once you used them and remember that Hypex states output into 4Ω, not 8.
I'm thinking if ATC tunes theirs to 29Hz in 100L they probably have a jolly good reason.
Have you considered to use a waveguide on the tweeter?
PS: Just noticed that you said you are producing music. In this case I would advise against using dsp to prop up the bass response of a sealed cab.
That eats headroom (excursion) like it is going out of fashion and sufficient headroom is vital in a studio environment IME.
It is all a compromise, I'm just stating where my preference lies.
Those Fusion amps look very interesting (at last!), let us know what you think of them once you used them and remember that Hypex states output into 4Ω, not 8.
I'm thinking if ATC tunes theirs to 29Hz in 100L they probably have a jolly good reason.
Have you considered to use a waveguide on the tweeter?
PS: Just noticed that you said you are producing music. In this case I would advise against using dsp to prop up the bass response of a sealed cab.
That eats headroom (excursion) like it is going out of fashion and sufficient headroom is vital in a studio environment IME.
Last edited:
Yes, that's what I was thinking.. but I have read contradictory things.
My calculations lead to 29Hz.. some others say they tune their housings to 23Hz which is the Fs of the 12" driver.. dunno 😕
I did! Thats why I asked about the Seas DXT tweeter.. it has a waveguide built in 🙂
H1499-06 27TBCD/GB-DXT
Yes those speakers are for mixing purposes.
There are more and more manufactures which use DSPs in their design in order to get bass response of closed cabinets right.. such as Kii Three, Barefoot Sound and Grimm LS1 to name a few
I was thinking Scanspeak R2604/833000 or Peerless/Vifa XT25BG60 which seems to be eminently suitable for waveguides although it does not come with one and so would need a bit of fiddling.
I'm fairly sure a member here once posted files to 3D print an adapter.
Somebody else measured it in a guide and it approached amplifier-like low levels of THD!
I don't think I'll ever make my peace with bass boost eq.
I'm fairly sure a member here once posted files to 3D print an adapter.
Somebody else measured it in a guide and it approached amplifier-like low levels of THD!
I don't think I'll ever make my peace with bass boost eq.
"bass boost eq" shoud actually be attenuation of upper frequencies! Then there is no risk of clipping distortion with digital signal. 24bit or floating 32bit dynamic scale used in studios (or even most dsp processors) gives enormous scale to play with.
The actual problem is spl vs distortion in the driver. This is mainly of concern in small 5-6½"monitors already below 200Hz, but a 3-way with 10-12" bass you must play really loud to hear problems. Doubling bass drivers is a good choice but the volume of the cabinet should be doubled too.
In the attached graphics there is a 6½" vs 10" sealed bass speakers in same outdoor measurement session. Compare spl vs distortion below 100Hz. AINOgradient has dsp and this measured response is straight down to 30Hz in the room. AW-7 is passive, it must be placed near the wall in the room.
One of the most important issues in loudspeaker design is to determine the maximum countinuous spl level required. Second is speaker placement, will the bass be helped by boundaries? These both affect bass max spl requirement, midrange and treble will not have similar problems, unless we start discussing PA systems.
The actual problem is spl vs distortion in the driver. This is mainly of concern in small 5-6½"monitors already below 200Hz, but a 3-way with 10-12" bass you must play really loud to hear problems. Doubling bass drivers is a good choice but the volume of the cabinet should be doubled too.
In the attached graphics there is a 6½" vs 10" sealed bass speakers in same outdoor measurement session. Compare spl vs distortion below 100Hz. AINOgradient has dsp and this measured response is straight down to 30Hz in the room. AW-7 is passive, it must be placed near the wall in the room.
One of the most important issues in loudspeaker design is to determine the maximum countinuous spl level required. Second is speaker placement, will the bass be helped by boundaries? These both affect bass max spl requirement, midrange and treble will not have similar problems, unless we start discussing PA systems.
Attachments
Last edited:
I am still hesistant.. a 3/4" tweeter is a decent suggestion.
but on the other hand smaller tweeter means more distortion when going lower and burnt out voice coils. The crossover is 4th order symmetrical (IIRC). So 3.5Hz is the -3dB point but it is generating below that. In addition, dispersion will be more spherical.
I think for now I will stick with the Seas DXT 1" waveguided tweeter.
Seem a good choice to me
@Juhazi:
Regarding my built I have decided to go for a BR cab.
done and tuned corrently it just seem as tight as a sealed cab would be.
despite the steeper roll-off below Fs I see no disadvantages
but on the other hand smaller tweeter means more distortion when going lower and burnt out voice coils. The crossover is 4th order symmetrical (IIRC). So 3.5Hz is the -3dB point but it is generating below that. In addition, dispersion will be more spherical.
I think for now I will stick with the Seas DXT 1" waveguided tweeter.
Seem a good choice to me
@Juhazi:
Regarding my built I have decided to go for a BR cab.
done and tuned corrently it just seem as tight as a sealed cab would be.
despite the steeper roll-off below Fs I see no disadvantages
^Low-tuned BR is a solid performer. Cabinet must be quite big, partly because the reflex channel must be long.
DXT is a nice tweeter, I have a pair as MarkK's ER18DXT. Don't get scared when looking at on-axis response! Still, LR4 above 3kHz should not be a problem for a 3/4" dome tweeter.
DXT is a nice tweeter, I have a pair as MarkK's ER18DXT. Don't get scared when looking at on-axis response! Still, LR4 above 3kHz should not be a problem for a 3/4" dome tweeter.
Attachments
Last edited:
In terms of woofer excursion vs SPL it makes no difference if you boost bass or cut everything else.
Not sure why you bring a 6.5" 'woofer' into this since the here the driver is a 12" which can do 30Hz at a given SPL either in a sealed cab (and possibly needing boost eq*) with high excursion or a ported cab with substantially lower excursion.
*couldn't find the T/S so didn't model
attatched you find the datasheet to the 12" ATC driver I will be using.
I already modelled in BassCAD .. giving a net volume of 100L I'd need a BR tube with 37cm length and a diamater of 10cm to archive 23Hz...
seems reasonable to me 🙂
http://www.diyaudio.com/forums/attachment.php?attachmentid=664705&stc=1&d=1519563337
IME when you use a calculator to model they all agree on box size, F3 etc but none seem to agree on port dimensions.
Something to bear in mind may be...
Something to bear in mind may be...
This clone from Wimslow Audio is excellent, very, very close of the original, you can use the same twetter:
K100 Monitor
K100 Monitor