You can eliminate the expensive L-pads for purposes of testing. Get an assortment of the Dayton Audio grade 10w white cement resistors. They are about $0.7ea and sound fine for 98% of speaker duties. Get several (4) of each value like 0.51R, 1R, 2R, 3.3R, 4.7R, 6.8R, 10R, 20R. You should be able to make any value you want to adjust the padding. It will sound better than an Lpad too. Use something like Wago quick connectors to make and swap connections.
For $200, I made myself essentially a complete XO development kit from inductors, caps, and resistors from PE’s inventory. My inductors range from 10mH (iron core) to 4mH air core down to 0.1mH all air core in nice increments and multiple ones of certain values to build any value I could reasonably need. Same with caps - I have film caps as large as 38uF, and down to 0.47uF. Multiple values of 1uF, lots of 2.2uF, 3.3uF, 4.7uF, lots of 5uF, 10uF, 22uF, 33uF, etc. a few 50uF BP’s , and big fat 60uF I got from Vunce as a gift. I also have a few 50uF motor run caps (not shown). And the R’s I already mentioned.
Now with this kit, I have been able to tackle 5 different custom crossover designs from scratch. That is, once I have the rough design in Xsim, I can immediately prototype the actual one from this $200 kit in minutes. No waiting for the parts to arrive, no wondering which part sounds better. I can hear it and measure right away. Make changes in real time and re-measure. It’s awesome.
Once I am happy, I order dedicated (possibly higher quality parts of needed) and return the items used for development back to their case for the next project.
Take for example my latest passive Harsch XO. I designed, built and tested this speaker in one night after I received the new PTT6.5 driver.
Prototype assembled in 15 minutes from the XO Dev Kit:
It sounds awesome! The permanent crossover parts are on their way, and I upgraded to a 0.68mH flat copper foil inductor that was on sale for $10ea! I used a $7 Mills resistor in 1 place only: the 2ohm attenuation (pad) for the tweeter. But total cost was well below $100 for stereo pair of XO’s.
Here is the XO Dev Kit:
For $200, I made myself essentially a complete XO development kit from inductors, caps, and resistors from PE’s inventory. My inductors range from 10mH (iron core) to 4mH air core down to 0.1mH all air core in nice increments and multiple ones of certain values to build any value I could reasonably need. Same with caps - I have film caps as large as 38uF, and down to 0.47uF. Multiple values of 1uF, lots of 2.2uF, 3.3uF, 4.7uF, lots of 5uF, 10uF, 22uF, 33uF, etc. a few 50uF BP’s , and big fat 60uF I got from Vunce as a gift. I also have a few 50uF motor run caps (not shown). And the R’s I already mentioned.
Now with this kit, I have been able to tackle 5 different custom crossover designs from scratch. That is, once I have the rough design in Xsim, I can immediately prototype the actual one from this $200 kit in minutes. No waiting for the parts to arrive, no wondering which part sounds better. I can hear it and measure right away. Make changes in real time and re-measure. It’s awesome.
Once I am happy, I order dedicated (possibly higher quality parts of needed) and return the items used for development back to their case for the next project.
Take for example my latest passive Harsch XO. I designed, built and tested this speaker in one night after I received the new PTT6.5 driver.
Prototype assembled in 15 minutes from the XO Dev Kit:
It sounds awesome! The permanent crossover parts are on their way, and I upgraded to a 0.68mH flat copper foil inductor that was on sale for $10ea! I used a $7 Mills resistor in 1 place only: the 2ohm attenuation (pad) for the tweeter. But total cost was well below $100 for stereo pair of XO’s.
Here is the XO Dev Kit:
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More history Dean. As an SFB/3 fan, I hope you will appreciate it:
British Industries Corporation (BIC) was the US agent for Wharfedale products, Garrard turntables and Leak amplifiers and was known as the 'Atlantic Pact' hi-fi firm.
BIC set up the subsidiary Wharfedale Audio Products to facilitate the marriage of Wharfedale drivers with locally sourced and styled enclosures.
In 1957, BIC produced its own versions of the SFB/3. The 'Warwick Custom' model was similar in appearance to the UK model but less austere, while the 'Windsor Deluxe' version appears to have the baffle contained in an ornate, open-backed cabinet. The two versions sold for $199 and $249 respectively.
(Information extracted from 'A Pair of Wharfedales' by David Briggs.)
British Industries Corporation (BIC) was the US agent for Wharfedale products, Garrard turntables and Leak amplifiers and was known as the 'Atlantic Pact' hi-fi firm.
BIC set up the subsidiary Wharfedale Audio Products to facilitate the marriage of Wharfedale drivers with locally sourced and styled enclosures.
In 1957, BIC produced its own versions of the SFB/3. The 'Warwick Custom' model was similar in appearance to the UK model but less austere, while the 'Windsor Deluxe' version appears to have the baffle contained in an ornate, open-backed cabinet. The two versions sold for $199 and $249 respectively.
(Information extracted from 'A Pair of Wharfedales' by David Briggs.)
I was looking at the - Dayton Audio grade 10w white cement resistors , you must have bought yours awhile ago , most are 1.41 ea. .... LOL
- I have a question how do i know that 10 watts resistor is enough for the tweeter? -
- And then the same question for the L-Pad that is on the eight inch Midrange.... the L-Pads are quite a bit more than 10 watts. The recommended size was 50 or 100 watt L-Pads , I'm sure part of that is to better dissipate the heat but......
- I have a question how do i know that 10 watts resistor is enough for the tweeter? -
- And then the same question for the L-Pad that is on the eight inch Midrange.... the L-Pads are quite a bit more than 10 watts. The recommended size was 50 or 100 watt L-Pads , I'm sure part of that is to better dissipate the heat but......
Only a small percentage of the total system power goes to the tweeter, typically 10%. Therefore, in the context of your W70 system, a 10W tweeter resistor is perfectly adequate.
A higher percentage of the total system power goes to the midrange and, for effective heat dissipation purposes, the L-Pad attenuator should be at least 50W.
A higher percentage of the total system power goes to the midrange and, for effective heat dissipation purposes, the L-Pad attenuator should be at least 50W.
A good 50watt potentiometer is $25.00 you can use a 2 to 10ohm 25watt resistor if saving money is important, a good foundation for a homemade crossover can be found by looking up B&W 802 DIAMOND .....as a matter of fact THIS is the midrange setup id use....its very great sounding........this is NOT what id use on woff or tweet although its close. Possibly To be continued
- thank you ... that makes sense about the tweeters that they would only see a few watts I guess , but is that because of the 4 uF ... or the 6.5 uF capacitor that is on them?....... ( that's all that is between them and the L-Pad)....
- Is there a way to measure , or make a good guess on what the amount of watts the resistors on the Midranges will need to be to replace the L-Pads there if I want to try that ?
- Hi Topping , are you saying that you would use the crossover design for the B&W 802 Diamond speaker midranges, on the 8 inch midranges in my Wharfedales? --
Is there only one year of B&W 802 diamond speakers? .... if not how will I know which is the right midrange crossover ? - Do you have a copy of it?Thank you
- Is there a way to measure , or make a good guess on what the amount of watts the resistors on the Midranges will need to be to replace the L-Pads there if I want to try that ?
- Hi Topping , are you saying that you would use the crossover design for the B&W 802 Diamond speaker midranges, on the 8 inch midranges in my Wharfedales? --
Is there only one year of B&W 802 diamond speakers? .... if not how will I know which is the right midrange crossover ? - Do you have a copy of it?Thank you
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1. Yes, only high frequencies reach the high frequency speaker because of the capacitor action.
2. Fixed resistors of 20W will be more than adequate for the midrange L-Pad.
Remember that the maximum power input to the W70 is in the order of 40W and the mid driver will only see a fraction of the maximum power, say 20W at the most.
You can confirm this by using the calculator which follows. Enter 20W where it asks for Amplifier Power/Channel. L-PADS
......XRK971 yes i agree you dont have to have L PADS at all.AND a cheap sand cast resistor is fine on a midrange.
....YUP B&W 802 s3 crossover upgrade ...plain as day layout....stick with the regular 802 ....not the upgrade.
Hi Topping , I looked up B&W 802 Diamond - 360,000 results, could you narrow it down a little Please?????? -- like a a link to click on -- or an specific page to look up ??????
--Also What I don't understand is why that crossover would work for the Wharfedale 8 inch Midrange, don't crossovers have to be specific to a driver ?? and Also what other drivers are in that crossover , and doesn't each crossover have to match the frequencys that the other drivers are crossing over at???
- The other problem is if I don't use the L-Pads , then I am changing the design of the speaker and might make it hard for resale.
- Topping - are you talking about Troelsgravesen's crossover upgrade?
--Also What I don't understand is why that crossover would work for the Wharfedale 8 inch Midrange, don't crossovers have to be specific to a driver ?? and Also what other drivers are in that crossover , and doesn't each crossover have to match the frequencys that the other drivers are crossing over at???
- The other problem is if I don't use the L-Pads , then I am changing the design of the speaker and might make it hard for resale.
- Topping - are you talking about Troelsgravesen's crossover upgrade?
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I guess I could make two crossover boards, one with the L-Pads , and one with the resister set up for me after I try and figure out which resisters to use ...
- or a switch to engage either the L-Pads or the Resisters ........
- I'm not sure what that would look like wiring wise ...
- You know what would be Really Nice and that would sound better - and make the crossover variable for the Resale is to set up the Midrange and Tweeter crossover with the same kind of simple Board design that Pure Audio Project is using , where they can just swap out components by using Screw terminals - - -
-- I'm not sure how to do the Layout for the Boards - Sure would be Nice though!!!
"We have then designed a unique Circuit Board with gold plated screw terminals that all components are mounted on. This audiophile-grade circuit board is made by Mundorf in Germany.
This tool-less swapping of components allows customers to carefully voice the crossover to the specific listening environment, the sonic signature of their equipment, and their personal sonic taste."
- or a switch to engage either the L-Pads or the Resisters ........
- I'm not sure what that would look like wiring wise ...
- You know what would be Really Nice and that would sound better - and make the crossover variable for the Resale is to set up the Midrange and Tweeter crossover with the same kind of simple Board design that Pure Audio Project is using , where they can just swap out components by using Screw terminals - - -
-- I'm not sure how to do the Layout for the Boards - Sure would be Nice though!!!
"We have then designed a unique Circuit Board with gold plated screw terminals that all components are mounted on. This audiophile-grade circuit board is made by Mundorf in Germany.
This tool-less swapping of components allows customers to carefully voice the crossover to the specific listening environment, the sonic signature of their equipment, and their personal sonic taste."
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If you looked at my link L-PADS you will have observed that an L-Pad consists of two resistors. The fact that the two resistors are variable is a distinct advantage in your case - no calculations and no experimenting with fixed resistor values. I'm afraid that I do not see the logic in switching between fixed resistors and a good quality L-Pad in the context of your vintage W70 speakers..
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