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Dr.db
09-19-2017, 01:22 PM
Can you recommend a L-Pad that is better sounding than the simple L-Padīs from partsexpress for 15$ ?

I have found some serious L-Padīs from Fostex, but they are only available in 8ohms...


Thanks a lot,
Olaf

Chevelle
09-19-2017, 11:33 PM
Hallo Olaf,

I use these heavy duty l-pads from Monacor: https://www.monacor.de/produkte/components/lautsprechertechnik/selbstbau/at-62st/

You can wire the stereo 8 ohms l-pad to a mono 16 ohms l-pad.

Gruß
Hjalmar

pos
09-20-2017, 12:31 AM
If autoformers are an option for you then I can definitly recommand Bob Crites' ones.
3dB steps version: http://www.ebay.com/itm/382061369270 (the one I used for fixed attenuation, with all the taps on one side)
1.5dB steps version: http://www.ebay.com/itm/371932355023 (more suited for a variable attenuator)

Dr.db
09-20-2017, 03:58 AM
Thanks a lot both of you!

I would like to stick with L-pads, as I have no experience with autoformers at all...
Rewire a stereo 8ohm L-pad to 16ohms seems to be an option, thank you. Are there any sonical drawbacks compared to a factory 16ohm l-pad ?

Odd
09-20-2017, 11:52 AM
I have bought these;

Speaker L-Pad Volume Attenuator AT-50H 50W RMS, 16 Ohms (http://www.ebay.com/itm/Speaker-L-Pad-Volume-Attenuator-AT-50H-50W-RMS-16-Ohms-potentiometer/112545385997?_trkparms=aid%3D222007%26algo%3DSIM.M BE%26ao%3D1%26asc%3D47507%26meid%3Def7b4ed556b045a 7ad7ed30c78553b6d%26pid%3D100011%26rk%3D2%26rkt%3D 4%26sd%3D122615975842&_trksid=p2047675.c100011.m1850)

They seem good quality.

pocketchange
09-23-2017, 08:15 PM
Keep in mind there are options that will do a better job.. pc

pos
09-24-2017, 12:16 AM
Can you please elaborate?

Dr.db
09-26-2017, 04:38 AM
Keep in mind there are options that will do a better job.. pc


And these would be...??

DogBox
06-11-2019, 10:15 PM
Hi All,

Seems as though L-Pads in 16 ohm impedance with a '1" Shaft' are as hard to find as obsolete JBL Recones! So builders of 43xx systems, "What are you using

for your L-Pads" in your build? Are the 50W ones capable enough when it states "100W"??

If anyone can Help or direct me to their availability - I would be most grateful!! :applaud::applaud::applaud: Even just to know if you're getting the 3/8" Shaft and extending it...?

What to do? :dont-know: :crying:

DogBox
[Steve]

dn92
06-21-2019, 12:04 AM
Can you recommend a L-Pad that is better sounding than the simple L-Padīs from partsexpress for 15$ ?

I have found some serious L-Padīs from Fostex, but they are only available in 8ohms...


Thanks a lot,
Olaf

take the r82b, it is a dual 16 ohm, just use one of the channels

Dr.db
06-21-2019, 07:59 AM
take the r82b, it is a dual 16 ohm, just use one of the channels

Are you shure?
On the fostex-website they claim 8 ohm...

JoeNelis
06-23-2019, 01:40 PM
I have used the TKD top of the range silver switches in my JBL DD 55000 project and although expensive they are stunning and worth the money.

Dr.db
06-25-2019, 12:40 AM
Could you please share a link of this particular product?

dn92
06-25-2019, 03:49 AM
Are you shure?
On the fostex-website they claim 8 ohm...

8ohm when connected in parallel as in the provided schematic. Each pad of the r82b is 16ohm.
I’ve a pair of them and measured this some time ago. You can go ahead with them.

dn92
06-25-2019, 03:52 AM
Otherwise you can search for Noble RPH25 (model used by TAD and Rey Audio) some of them used by Yamaha are 16ohm while the majority of them on second hand market are 8ohm.
I’ve two of them in stock in 16ohm that I’m not using, MP in case of interest.

Dr.db
06-25-2019, 11:37 AM
Thanks, now I understand how to use the R82b to operate at 16ohms!
I expect the Fostex R82B to be of much better quality than the simple parts-express l-pads. But the way they work is the same, isnīt it?
Whereas the Fostex R100T is different, they call it transformer type attentuator... but these are only 8ohms...

Thanks for your offer of the Noble RPH25, but I would prefer new ones.
But I suspect these arenīt available, are they?
And again, are these functioning like the usual l-pads and just of better quality?
Or are these something special like the Fostex R100T ?

dn92
06-25-2019, 12:01 PM
Fostex r100 are autotransformer which is different from usual Lpads. Noble RPH25 is not available anymore, only on second hand market.

https://m.review33.com/forum_msg.php?db=1&topic=92100413141952&number=11&sort=1

Dr.db
06-25-2019, 12:22 PM
Ok, so R82b and Noble RPH25 are usual lpads.

Are you aware of any other autotransformers on the market today?

dn92
06-30-2019, 02:02 PM
Ok, so R82b and Noble RPH25 are usual lpads.

Are you aware of any other autotransformers on the market today?

There are nice autotransformers from Germany ;-) on eBay.
I'll try to find the link. I had the opportunity to measure two of them, and they work well. You can use them directly with Compression driver/Horn (with a power resistor in parallel to the input) like in the TAD DN2404 crossover. Distorsion only rises below 600Hz.

Note: it is there, with explanations in German special for yourself: https://www.ebay.fr/itm/Autotransformer-passend-fur-Altec-and-other-Horn-Projekte/223474615931?hash=item340820067b:g:wRQAAOSwLjRa6v0 N

Dr.db
07-01-2019, 01:02 PM
Thanks a lot for providing this very useful link! ;)

I have to ask this silly question; do autoformers sound better than usual resistors e.g. l-pads?
Some people dislike resistors/l-pads in crossovers... But than again, JBL got rid of these in their crossovers years ago. Especially Greg Timbers wasnīt a big fan of autoformers anymore...

But Iīm still wondering why they used autoformers in the past rather than using resistors. Autoformers must have been of some advantage, if not why use these more expensive autoformers when you could use cheaper resistors instead?

Kay Pirinha
07-02-2019, 07:08 AM
Hi,

the main advantages are that autoformers per se don't dissipate heat and that output impedance, as seen by the driver, won't increase when turning ccw. In contary it will decrease then. But there's also a big disadvantage: Input impedance, as seen by the filter, will increase when turning ccw. Xover designers have to cope with this, as otherwise the frequency reesponce depends on the attenuator setting.

Best regards!

dn92
07-02-2019, 03:04 PM
Input impedance variation is compensated by the resistor placed in parallel to the autotransformer input. With the apropriate resistor value, circuit input impedance will be the one of the resistor. For the model I provided the link I used a 8.2 ohm power resistor.

toddalin
07-07-2019, 11:40 AM
Just have to know where to look. I used these on the Ethyl Mermans for the 16 ohm 2251Js. You can also get them on ebay if you look for Fender L-pads. Ebay doesn't list the impediance, but uses the same part # and IIRC, that's where I got mine.

https://www.guitarpartsfactory.us/index.php?route=product/product&product_id=5172

Dr.db
07-11-2019, 12:02 PM
@Kay Pirinha & dn92:

In laymans terms; what is the difference in sound? :)

@Tod:

I bet not many are aware of these, great ;)