Hi All,
I recently took the plunge on a pair of TAD 1601a woofers and the TH-4001 horn that popped up for a good price. So now I find myself committed to a build..
It's always been a dream to replicate the exclusive 2402, but purchasing the TD-4001 drivers is out of reach right now. I was considering a pair of JBL 2450H's, as I've seen them recommended here as a good match for the TH-4001?
I plan to go active, with a digital crossover via minidsp flex. I have an Elekit tu-8900 for the horn. And an Amp Camp amp for the woofers at the moment- I realise this is probably a bit underpowered, but have to work with what I've got until I can buy or build something with a bit more grunt. To compensate for this, I planned to cross the woofers at 80hz or so to a ported Rythmik 12" sub I have.
I was thinking of crossing horns at about 600hz. Tips on crossover for this combo also appreciated.
Frying the compression drivers is probably my biggest fear with the digital crossover, so was thinking 33 or 47µF film capacitor in series - need some advice on this especially.
Eventually I'd like to build full size cabinets in the style of the originals, but for the time being (due to space constraints and the amp/sub situation above) I was thinking of building a temporary 120 litre sealed cabs for testing, since I'll not be asking too much in the bass department of 1601a's.
Anyway just thought I'd put this out to the brains trust for some opinions on the approach and any considerations I may have missed. Realise there is a lot to learn/consider so not in any rush, and flexible with the plan, these are moreso just initial thoughts. Thanks in advance!
I recently took the plunge on a pair of TAD 1601a woofers and the TH-4001 horn that popped up for a good price. So now I find myself committed to a build..
It's always been a dream to replicate the exclusive 2402, but purchasing the TD-4001 drivers is out of reach right now. I was considering a pair of JBL 2450H's, as I've seen them recommended here as a good match for the TH-4001?
I plan to go active, with a digital crossover via minidsp flex. I have an Elekit tu-8900 for the horn. And an Amp Camp amp for the woofers at the moment- I realise this is probably a bit underpowered, but have to work with what I've got until I can buy or build something with a bit more grunt. To compensate for this, I planned to cross the woofers at 80hz or so to a ported Rythmik 12" sub I have.
I was thinking of crossing horns at about 600hz. Tips on crossover for this combo also appreciated.
Frying the compression drivers is probably my biggest fear with the digital crossover, so was thinking 33 or 47µF film capacitor in series - need some advice on this especially.
Eventually I'd like to build full size cabinets in the style of the originals, but for the time being (due to space constraints and the amp/sub situation above) I was thinking of building a temporary 120 litre sealed cabs for testing, since I'll not be asking too much in the bass department of 1601a's.
Anyway just thought I'd put this out to the brains trust for some opinions on the approach and any considerations I may have missed. Realise there is a lot to learn/consider so not in any rush, and flexible with the plan, these are moreso just initial thoughts. Thanks in advance!
The TH-4001 has a minimum dimension of 24cm. Polars would confirm whether crossing below 2kHz is suitable for your configuration.
When you use a capacitor close to the crossover frequency, there are benefits to keeping it installed for the measurement set used to create a crossover for it. That's not to say you might not choose to measure without it while doing your initial acoustic assessment.
Hi @AllenB
Thanks very much for the reply. Good point, I'll do some polars to confirm, but was thinking around there would be a good starting point if I'm shooting for a similar result to the original design? Although I'm not using the TD-4001, so not sure how significantly differently another compression driver would behave.
That's a good tip re: keeping the capacitor in place when designing the crossover. I'll most likely just leave it in until I'm more comfortable with the setup - it's a bit too easy to accidentally switch crossover presets with the remote on the minidsp..
Thanks very much for the reply. Good point, I'll do some polars to confirm, but was thinking around there would be a good starting point if I'm shooting for a similar result to the original design? Although I'm not using the TD-4001, so not sure how significantly differently another compression driver would behave.
That's a good tip re: keeping the capacitor in place when designing the crossover. I'll most likely just leave it in until I'm more comfortable with the setup - it's a bit too easy to accidentally switch crossover presets with the remote on the minidsp..
You can use the TD-4001, TD-4002 with adapter, JBL 2450H,
DAS ND-8 and K-8 should also "fit" but can't confirm it, never had one.
The "snoutless" versions are identical" to the JBLS's.
This is why if you were wondering.
JBL 2450H/J, 2450J-1, Meyer Sound MS2001A ,
TD-4001, TD-4002,
Throat diameter [mm] 49.2
Throat angle [deg] 10
Equiv. Fc (Exp) [Hz] 217
Equiv. Fc (Hypex T=0.7) [Hz] 290
Equiv. Fc (Hypex T=0.6) [Hz] 320
JBL 2450H/J, 2450J-1, Meyer Sound MS2001A ,
TD-4001, TD-4002,
Throat diameter [mm] 49.2
Throat angle [deg] 10
Equiv. Fc (Exp) [Hz] 217
Equiv. Fc (Hypex T=0.7) [Hz] 290
Equiv. Fc (Hypex T=0.6) [Hz] 320
JBL 2450J (or H) is a great choice.
I'd recommend retrofitting a Radian Al diaphragm, though (https://radianaudio.com/products/1245-diaphragm)
The ribbed-Ti one that comes stock with the driver sounds a bit harsh in the upper treble (and this is shown as "hash" in the waterfall plots, too).
I'd recommend retrofitting a Radian Al diaphragm, though (https://radianaudio.com/products/1245-diaphragm)
The ribbed-Ti one that comes stock with the driver sounds a bit harsh in the upper treble (and this is shown as "hash" in the waterfall plots, too).
Thanks @marco_gea , I picked one up yesterday - I think it was actually your original posts I was referencing for the recommendation.
Thanks for the tip on the diaphragm. I'll try the originals for a bit and see how they go - but it's great to have an upgrade path. I saw they have a Beryllium version too, but the only price I could find was $1200usd a pop - at which point it probably makes more sense to pick up a pair of td-4001's..!
What crossover parameters did you settle on if you don't mind sharing? Anything to watch out for in your experience? Could be handy to use as a starting point.
Thanks again
Thanks for the tip on the diaphragm. I'll try the originals for a bit and see how they go - but it's great to have an upgrade path. I saw they have a Beryllium version too, but the only price I could find was $1200usd a pop - at which point it probably makes more sense to pick up a pair of td-4001's..!
What crossover parameters did you settle on if you don't mind sharing? Anything to watch out for in your experience? Could be handy to use as a starting point.
Thanks again
The smooth, aquaplased 2450/2452 SL diaphragms works very well also.
So there are plenty of options.
So there are plenty of options.
Having various diaphragm options is one of the pluses of the JBL large-format drivers.
As to crossovers, I tried many configurations, passive, analogue active and DSP.
I "settled" for a relatively humble but satisfactory DBX analogue active unit, 24dB/oct LR, with front-to-back offset adjusted to obtain phase match at Fx.
As to crossovers, I tried many configurations, passive, analogue active and DSP.
I "settled" for a relatively humble but satisfactory DBX analogue active unit, 24dB/oct LR, with front-to-back offset adjusted to obtain phase match at Fx.
I played around with some simulations in Winisd to maybe help you understand what can be expected from TL-1601a.
I also included a pair of simulations with it's successor TL-1601b that is better suited for a ported design.
I think TL-1601a can be used in a ported design, but would better of in a passive radiator system or in a sealed enclosed with a sub as you are planning.
All these simulation have the gain of a 30 m2 room added so this is estimated in-room responses.
Ranged from the top at the 30Hz vertical line:
Dark blue: TL-1601a in 105 liter ported enclosure.
Light green: TL-1601b in 97 liter ported enclosure
Red: TL-1601b in 92 liter ported enclosure
Purple: TL-1601a in 120 liter sealed box
Dark green: TL-1601a in 60 liter sealed box
Personally I would select 60 before 120 liter sealed box when combining with a sub.
You will exite less room resonances and get a little peak at 100-200 Hz that will help to compensate for the dip that often occur in 100-200 Hz because of floor reflection if bass driver are placed with some distance above the floor. I assume you want to do that to not have a too low position of midrange in the soundstage.
I also included a pair of simulations with it's successor TL-1601b that is better suited for a ported design.
I think TL-1601a can be used in a ported design, but would better of in a passive radiator system or in a sealed enclosed with a sub as you are planning.
All these simulation have the gain of a 30 m2 room added so this is estimated in-room responses.
Ranged from the top at the 30Hz vertical line:
Dark blue: TL-1601a in 105 liter ported enclosure.
Light green: TL-1601b in 97 liter ported enclosure
Red: TL-1601b in 92 liter ported enclosure
Purple: TL-1601a in 120 liter sealed box
Dark green: TL-1601a in 60 liter sealed box
Personally I would select 60 before 120 liter sealed box when combining with a sub.
You will exite less room resonances and get a little peak at 100-200 Hz that will help to compensate for the dip that often occur in 100-200 Hz because of floor reflection if bass driver are placed with some distance above the floor. I assume you want to do that to not have a too low position of midrange in the soundstage.
Yes, obviously putting a rather "fragile" driver in a tiny closed box ,and applying some EQ boost to feed it some more power, is probably the best solution for it. Especially as it's problems with heat buildup and demagnetization is so widely known.
There is no chance that someone like Kinoshita who built a large number of monitors with them, and worked on the development along with Locanthi would know how to better use them. Or TAD's research and development lab.
The TL-1601B (and 1603 even more so), is the direct result of needing more thermal capability in the drivers to avoid the issue.
That is why you find fx. vented VC former, and vented motor structure under the spider on the 1601B/1603.
If you do so do be mindful of what kind of power you put into the drivers over long sessions.
There is no chance that someone like Kinoshita who built a large number of monitors with them, and worked on the development along with Locanthi would know how to better use them. Or TAD's research and development lab.
The TL-1601B (and 1603 even more so), is the direct result of needing more thermal capability in the drivers to avoid the issue.
That is why you find fx. vented VC former, and vented motor structure under the spider on the 1601B/1603.
If you do so do be mindful of what kind of power you put into the drivers over long sessions.
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Hi all, many thanks for the replies and apologies for the lateness of mine - life got in the way a bit this week.
As per original post, given current space constraints (and for simplicity - not sure I'm confident getting a port tuned properly yet), I thought I would shoot for a roughly 103 litre sealed cabinet based. I'll cross to the sub around 50-80Hz.
Given the TAD TL-1601a parameters (Fs=28Hz, Qts=0.34, Vas=307L), I've roughly calculated the below design:
- External Dimensions: 612mm (W) x 612mm (H) x 378mm (D)
(Width matches the TH-4001 horn; depth was adjusted to hit the target volume and space constraints)
This alignment seems to offer reasonably flat response within the range, and good damping. The TADs would not be responsible for deep sub-bass, so should hopefully help alleviate any heat/stress concerns in the smaller than usual cabinet.
Would appreciate any thoughts or considerations for this approach, and if I'm missing / miscalculated anything important.
Thanks again for all the help.
rough mockup for reference:
As per original post, given current space constraints (and for simplicity - not sure I'm confident getting a port tuned properly yet), I thought I would shoot for a roughly 103 litre sealed cabinet based. I'll cross to the sub around 50-80Hz.
Given the TAD TL-1601a parameters (Fs=28Hz, Qts=0.34, Vas=307L), I've roughly calculated the below design:
- External Dimensions: 612mm (W) x 612mm (H) x 378mm (D)
(Width matches the TH-4001 horn; depth was adjusted to hit the target volume and space constraints)
- Material Thickness: 25mm
- Calculated Gross Internal Volume: ~103.6 Liters
- Estimated Net Internal Volume (Vb) (after ~5L driver & ~6L bracing): ~92.6 Liters
- Resulting System Qtc: ~0.706
- Calculated Anechoic F3: ~58.2 Hz
This alignment seems to offer reasonably flat response within the range, and good damping. The TADs would not be responsible for deep sub-bass, so should hopefully help alleviate any heat/stress concerns in the smaller than usual cabinet.
Would appreciate any thoughts or considerations for this approach, and if I'm missing / miscalculated anything important.
Thanks again for all the help.
rough mockup for reference:
PS for the compression driver protection, I was thinking of going with 100µF ClarityCap PX rated for 250VDC. From what I can figure this gets me:
- 200 Hz: -3 dB
- 100 Hz: Approx. -7 dB
- 50 Hz: Approx. -12.3 dB
- 25 Hz: Approx. -18.1 dB
Hi All,
So received the TAD TL-1601a's today - good news, they measure 7.0 and 7.1 ohms each, so resistance seems to be within spec.
The JBL 2450H's not so much luck - one measures 4.5 and one measures 8.2 ohms. The one measuring 8.2 looks a bit rougher inside, and they seem to have mismatched diaphragms. I thought perhaps one of them was fitted with a 16ohm diaphragm and that could explain the large discrepancy?
From what I understand an 8 ohm diaphragm should have 4ohm DCR, and a 16 should be 8.
Here is the one measuring 4.5ohms:
Here is the one measuring 8.2ohms:
Not quite sure what to make of the part numbers. But I guess the plan now is to buy replacement diaphragms. It's safe bet to say they would be the only part to have a fault right? Just hesitant to pour too much more money into them if they might be cooked..
Thanks again
So received the TAD TL-1601a's today - good news, they measure 7.0 and 7.1 ohms each, so resistance seems to be within spec.
The JBL 2450H's not so much luck - one measures 4.5 and one measures 8.2 ohms. The one measuring 8.2 looks a bit rougher inside, and they seem to have mismatched diaphragms. I thought perhaps one of them was fitted with a 16ohm diaphragm and that could explain the large discrepancy?
From what I understand an 8 ohm diaphragm should have 4ohm DCR, and a 16 should be 8.
Here is the one measuring 4.5ohms:
Here is the one measuring 8.2ohms:
Not quite sure what to make of the part numbers. But I guess the plan now is to buy replacement diaphragms. It's safe bet to say they would be the only part to have a fault right? Just hesitant to pour too much more money into them if they might be cooked..
Thanks again
The lower driver is missing a gasket?
And looks like it has been exposed to some moisture.
Cover the gap with masking tape, and scurb off the corrosion with solvent etc.
Anf after clean the VC gaps with som folded over tape etc.
You can find some basic videos on how on youtube.
Fx satria speaker on YT, or one of the american repair shops( name escapes me right now).
And yes you likely have 1x 8 and 1x 16 ohm diaphragm.
For use all the way up, you will be much better off with a pair of Aquaplased JBl (2450sl /2452hsl), or Radian AL diaphragms as explained.
And looks like it has been exposed to some moisture.
Cover the gap with masking tape, and scurb off the corrosion with solvent etc.
Anf after clean the VC gaps with som folded over tape etc.
You can find some basic videos on how on youtube.
Fx satria speaker on YT, or one of the american repair shops( name escapes me right now).
And yes you likely have 1x 8 and 1x 16 ohm diaphragm.
For use all the way up, you will be much better off with a pair of Aquaplased JBl (2450sl /2452hsl), or Radian AL diaphragms as explained.
@Arez - Fantastic thanks very much for the info.
Apologies it does have the gasket, but I removed it when inspecting.
Yeah that one has some pretty bad corrosion - thanks for the tips, I'll give that a try.
Is light sanding and then vaccuming or blasting some air through ok? Looks like there could be a bit rough in the voice coil gap also.
Obviously some care needs to be taken when centring the voice coil - but not sure how in depth I need to get. On the channel you mentioned he seems to be using a signal sweep when centring - is that to listen for any noticeable distortion?
Then there's this thread where he's using a depth gauge jig https://www.audioheritage.org/vbull...-2451-D8R2450SL-diaphragm-installation-method
Just to confirm, this is the aquaplas version you're referring to? The radian does look good also, but if I have that right it's quite a bit more expensive so may start with these.
https://reconingspeakers.com/product/jbl-d8r2450sl-diaphragm/
Apologies it does have the gasket, but I removed it when inspecting.
Yeah that one has some pretty bad corrosion - thanks for the tips, I'll give that a try.
Is light sanding and then vaccuming or blasting some air through ok? Looks like there could be a bit rough in the voice coil gap also.
Obviously some care needs to be taken when centring the voice coil - but not sure how in depth I need to get. On the channel you mentioned he seems to be using a signal sweep when centring - is that to listen for any noticeable distortion?
Just to confirm, this is the aquaplas version you're referring to? The radian does look good also, but if I have that right it's quite a bit more expensive so may start with these.
https://reconingspeakers.com/product/jbl-d8r2450sl-diaphragm/