Lab 12 Based Offset Driver - Mass Loaded - Transmission Line (OD-ML-TL) Design by Bj

[tb46]

Post #280 - Felt and Damping

Hi NWCgrad,

David McBean has added the ability to add stuffing to the simulation, and it clearly indicates, that this enclosure would be best build w/ very little absorptive material, if any at all.

For the first test build I would not use any stuffing at all, or just a little around the S1 end of the duct. Remember, we really squeezed the last little bit of volume out of this box.

The reduction in cross-sectional area caused by the 1/4" felt would probably not hurt anything, but stuffing the duct should be done very lightly (and go for the less expensive stuff).

I wish bjorno would take a look at this, he knows so much more about this subject than I do.

Regards,

 

[NWCgrad]

Hi NWCgrad,

David McBean has added the ability to add stuffing to the simulation, and it clearly indicates, that this enclosure would be best build w/ very little absorptive material, if any at all.

For the first test build I would not use any stuffing at all, or just a little around the S1 end of the duct. Remember, we really squeezed the last little bit of volume out of this box.

The reduction in cross-sectional area caused by the 1/4" felt would probably not hurt anything, but stuffing the duct should be done very lightly (and go for the less expensive stuff).

I wish bjorno would take a look at this, he knows so much more about this subject than I do.

Regards,

Thanks Oliver

Interesting...if I can get by without the felt I would be pretty happy as they don't give it away. Will try some light stuffing with fiberglass or pillow stuffing near the S1 end. Would be nice to reduce some of the calculated ringing above the LPF that could be audible. However don't want to reduce output.

 

[NWCgrad]

and so it begins....

Finally picked up two sheets of 13 ply Baltic birch from a local vendor. Its grade A-1 and looks pretty solid. After forever I will make sawdust this weekend.

 

[qu1cks1lver56]

PLEASE tell me you've built this and have heard how it sounds. I have a pair of LAB12's dying for an enclosure. I've been a fan of transmission lines for quite a while and have been wondering how I could do one that would fit in my car for these drivers. 2 of these side by side in my SUV would be a perfect fit.

 

[DrDyna]

PLEASE tell me you've built this and have heard how it sounds. I have a pair of LAB12's dying for an enclosure. I've been a fan of transmission lines for quite a while and have been wondering how I could do one that would fit in my car for these drivers. 2 of these side by side in my SUV would be a perfect fit.

Stick a Fosgate R1200d on a pair of them and you should be in for a serious "ear plugs necessary" type of good time.

 

[qu1cks1lver56]

I actually have a silver face Fosgate T10001bd waiting for some subs to hammer on.

 

[Etocynned]

Ahh the BD1000, good times, good times.

Those amps were sooooooo good, used to sell them.

pics?

 

[qu1cks1lver56]

I can get some, I had a pair of them in my old truck on a pair of 15's in a 4th order.

 

[DrDyna]

Ahh the BD1000, good times, good times.

Those amps were sooooooo good, used to sell them.

pics?

Not to wander too far off topic, but I remember the Fosgate amps that were referred to as "cheater" amps..I think they were designed to run from 24v, but they were labelled like "50M".. which was actually a 500w if you cranked the voltage and ran it into half-ohm loads.

Then Harman took over.

 

[Etocynned]

they_were_high_current_unregulated_amps.

Stable_to_.25Ohm,load_em_up!

Our_installer_had_6_running_30_DVC12's_in_his_blazer,WOOMP!

 

[BP1Fanatic]

I have 2 Punch 45HD's!

 

[kees52]

I did read this, and tought I go try such box for sub, it go low and have decent efficienty.

But I did see also the port problems of bjorno design who are drawn in hornresp but the flares on the gegin and end off that port to minimixe noise and losses can not properly be drawn in hornresp, I have the martin sheets bought some time ago for the open baffles and U frames . there are also ml-tl sheets who can input the complicated port design.

Nice designs here, not so big and good respons, thread is old but I gess it wil be read.

 

[tb46]

Hi kees52,

Post #292: "...the flares on the gegin and end off that port to minimixe noise and losses can not properly be drawn in hornresp..."

You could use the OD driver arrangement to simulte a OD MLTL w/ a normal straight port, then use the Nd driver arrangement to simulate a standard vented box w/ a similar internal volume and port, and then convert that simulation into a jet port simulation. You could then transfer that jet port design into your drawing for the OD-MLTL. Or you could just go to AkAbak.

I'll attach a Hornresp export file for a jet port example.

Regards,

 

[kees52]

Hi kees52,

Post #292: "...the flares on the gegin and end off that port to minimixe noise and losses can not properly be drawn in hornresp..."

You could use the OD driver arrangement to simulte a OD MLTL w/ a normal straight port, then use the Nd driver arrangement to simulate a standard vented box w/ a similar internal volume and port, and then convert that simulation into a jet port simulation. You could then transfer that jet port design into your drawing for the OD-MLTL. Or you could just go to AkAbak.

I'll attach a Hornresp export file for a jet port example.

Regards,

Hi TB46

Thanks for your help, I did read somewhere that simulate a jet port is not easy because there is not much data, I can use the sheets from Martin, I have bough these past year but also here it is not rounded but flare, best was een straight pipe and software who translate that in a jet of so.

thanks again ik go look at it. Akabak is a little to difficult, I can work with if if I have ready made input, then martin sheets are more easy for me..

Here a sim with isobaric wsp 25s visaton woofers who already have seen some differend homes, not a problem because she have not to pay rent.

And a picture of the open baffles left and a T-TQWT on the left in corner, this do sound very good, I like ripole bass a lot, see last picture the measurement of the open baffle/T-TQWT.

First picture is of a OD-ML-TL, I did like the efficienty, this photo is the visatons in isobaric, it is ugly afcourse a pointing out speaker in such system other then the T-TQWT.

regards

kees

 

[kees52]

TB 46

I have done the sub like you say, I have tune the pipe on the same low point as te original ML-TL, and put it together in the sub itselfs giving it that noiseless port.

Do you have somewhere also a akabak example?

see text so you can see if I are oke.

thanks

kees

 

[tb46]

Hi kees52,

Sorry, but I have some things coming up that'll leave me very little time. I'm attaching the Hornresp AkAbak Export for the Hornresp simulation in Post #293. It seems to work fine in AkAbak (after you change the extension back to .aks).

Regards,

 

[kees52]

Hi kees52,

Sorry, but I have some things coming up that'll leave me very little time. I'm attaching the Hornresp AkAbak Export for the Hornresp simulation in Post #293. It seems to work fine in AkAbak (after you change the extension back to .aks).

Regards,

Thanks TB46 for the script, now I can play with akabak a little, I did see that martins sheets also are usable, I do have this sheets.

Burt first to the dentist, the toothpain is not so nice, I had a visite to the dentist past week, but he did something not good, drilling to deep and now it is infected, and believe me it hurt.

regards

kees

 

[kees52]

Can akabak give a schematic like hornresp do?

 

[Zero D]

@ kees52

Nice LF extension you got there Plus good upwards too

 

[kees52]

@ kees52

Nice LF extension you got there Plus good upwards too

It is even better with isobaric high vas speakers.

visaton wsp26s example.

regards.