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ALK xover - DIY for Forte II schematic


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Having spoken with him directly I can easily see where all of you are coming from with ALK. Being I came on here well after the fact it was my nature to give him the benefit of a doubt when I read his comments on his web site. Luckily I was able to find his design for the  Forte II.

 

 

As on the coils, I will look at the cost difference and if it amounts to a sizable dollar savings I would go down to "regular" parts.  Aside from cost and possible size is there any reason not to replace an iron core with an air coil inductor?

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2 hours ago, Alexander said:

Having spoken with him directly I can easily see where all of you are coming from with ALK. Being I came on here well after the fact it was my nature to give him the benefit of a doubt when I read his comments on his web site. Luckily I was able to find his design for the  Forte II.

 

 

As on the coils, I will look at the cost difference and if it amounts to a sizable dollar savings I would go down to "regular" parts.  Aside from cost and possible size is there any reason not to replace an iron core with an air coil inductor?

 

Hearsay is that it matters less on the low end.  

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8 hours ago, Alexander said:

As on the coils, I will look at the cost difference and if it amounts to a sizable dollar savings I would go down to "regular" parts.  Aside from cost and possible size is there any reason not to replace an iron core with an air coil inductor?

 

Iron core inductors don't radiate their inductance as much as air core, so if you use an air core inductor first it will be larger and second it may interfere with other inductors on the board.

I take it that you are going to use ALK's layout as detailed in the original thread and so you will have to alter the layout to accommodate the larger coil . ALK always tests his layouts to ensure the inductors do not interfere with each other and skew the response.

Here is a primer on inductor layout - http://www.troelsgravesen.dk/coils.htm

My advice would be to stick with the iron core and ALK's layout.

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Thanks, I could have follows the schematic but this will make things much easier for these old eyes :) 

 

Haven't decided on what to use as a common ground, like the braid but just can't find any without getting a crazy amount/price. Also thought of buss wire but again the same deal with the braid, money is very much an issue so I will most likely make the spine out of 14 or 16 gauge wire from my junk box. 

 

Any more thoughts of using smaller gauge inductors? Looking at #18 2.0 iron & #20 (18?) air for the 1.6,.20 and .30. As thorough as ALK seems to be using a smaller gauge can and will change (increase) the DC resistance values so it raises the question if this would be a factor in the design enough to require other changes.

Edited by Alexander
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revised price list, the original list had prices with a few things on sale.

 

      Price each Per Sspeaker Source Part #      
Caps               Caps Total  
1 33uf Mylar   $- $- solen PEMT-   $36.73  
1 27uf   $14.23 $14.23 solen pb2700      
1 18uf np   $1.30 $1.30 solen B05A100K186      
1 7.5uf   $5.00 $5.00 meniscus S7.5      
2 2.2uf   $2.77 $5.54 meniscus S2.2      
                   
                   
                   
Inductors               inductor total  
1 2.0 mh iron   $13.23 $13.23 meniscus SL2   $40.93  
1 1.6mh soildw   $7.65 $7.65 solen S201.6      
                   
1 .20mh16Litz   $9.07 $9.07 solen L16.20      
1 .30mh#16Litz   $10.98 $10.98 solen L16.30      
                   
                   
                   
Resistors               resistor total  
1 30ohm   $1.27 $1.27 meniscus L30   $5.08  
1 9.1ohm   $1.27 $1.27 meniscus L9.1      
1 6.8ohm   $1.27 $1.27 meniscus L6.8      
1 39ohm   $1.27 $1.27 meniscus L3.9      
                Total per speaker  
                82.74  
Edited by Alexander
fixing errors
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Boards, pair of transformers, terminal strips, solder lugs, screws, wire, ground strap, cap fasteners, tie wraps..........just a few more items.  Those should turn out nice.

 

I would also consider a pair of the ALK tweeter attenuator transformers, so you have a totally adjustable network.  The tweeters are going to be a little hot without them.

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I got some 8-10 gauge solid copper at an armature / motor rewinding shop. It wasn't expensive. Purchased by the foot... you could do the same at Lowe's/HF/Menards, etc.

 

Bruce

 

 

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Litz has less loss, but it's not audible. 

 

Put your money into film and tin foil capacitors - an improvement you can hear and appreciate. 

 

Iron core and steel laminates are fine in the low pass section, but keep DCR close to stock or below. 

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6 hours ago, mark1101 said:

I would order everything from Solen in Canada.  Prices are all in Canadian dollars.

 

https://solen.ca/orders/

 

 

Already have a spare set of T7A's, would love to get everything from one place but Solen doesn't have everything needed. Besides all the ancillary fees add up quickly, as simply as adding eight resistors adds over $4 to shipping

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4 hours ago, Marvel said:

I got some 8-10 gauge solid copper at an armature / motor rewinding shop. It wasn't expensive. Purchased by the foot... you could do the same at Lowe's/HF/Menards, etc.

 

Bruce

 

 

Great idea, I will get a few feet of 3/12 or 3/10 wire and cut out the ground. Thanks 

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2 hours ago, Deang said:

Litz has less loss, but it's not audible. 

 

Put your money into film and tin foil capacitors - an improvement you can hear and appreciate. 

 

Iron core and steel laminates are fine in the low pass section, but keep DCR close to stock or below. 

film & tin foil caps? Could you give me a few venders that offer them? Also are we saying that the DCR of the 1.6, .20 & .30mh coils are not a factor to be concerned then? I believe the #18 2.0 steel laminate was below .4 ohm but will confirm this.

 

Just checked, it is .26 ohms

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In the high pass. 'Q' dominates - I just can't hear the difference between Litz and normal air cores if DCR is kept close to the same. 

 

I like the Jantzen air cores from Parts Express. 20 gauge for the 1.6mH, and 15 gauge for the .20 and . 30. 

 

AudioCap PPT Thetas in the high pass - can be found at www.soniccraft.com and www.partsexpress.com. 

 

AudioCap at the primary position- can be found at www.partsconnexion.com.

 

Vendors are often prone to voodoo nonsense, however, the aforementioned parts are excellent.

 

Eat the meat and spit out the bones. 

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1 hour ago, Alexander said:

Already have a spare set of T7A's, would love to get everything from one place but Solen doesn't have everything needed. Besides all the ancillary fees add up quickly, as simply as adding eight resistors adds over $4 to shipping

 

My point was that the US Dollar is buying about $1.35 Canadian.  The Solen prices are all in Canadian and there is no duty or tax.  That's like 35% off right there.

 

You mentioned saving money.

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1 hour ago, Alexander said:

Great idea, I will get a few feet of 3/12 or 3/10 wire and cut out the ground. Thanks 

 

They have bare wire for grounds (water heaters, etc.) No need to buy other and strip.

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I stand corrected, I could not find any mention on their site about any exchange. I went forward in placing an order and it wasn't until we were in Papal did the exchange rate was shown. It is currently at 1.30 which works out to .77us per $1 can. Thanks, I did order everything I could from them.

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11 hours ago, Deang said:

In the high pass. 'Q' dominates - I just can't hear the difference between Litz and normal air cores if DCR is kept close to the same. 

 

I like the Jantzen air cores from Parts Express. 20 gauge for the 1.6mH, and 15 gauge for the .20 and . 30. 

 

AudioCap PPT Thetas in the high pass - can be found at www.soniccraft.com and www.partsexpress.com. 

 

AudioCap at the primary position- can be found at www.partsconnexion.com.

 

Vendors are often prone to voodoo nonsense, however, the aforementioned parts are excellent.

 

Eat the meat and spit out the bones. 

Thank you Dean, I found the price difference between the Litz vs non was about $6 total for the four coils so I went ahead and got them. Wow, those AudioCap PPT Thetas are way out of my present price range. But the way the layout is setup it would be very easy to change out the caps at a later date.

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11 hours ago, Marvel said:

 

They have bare wire for grounds (water heaters, etc.) No need to buy other and strip.

Lowe's (my only choice around here in Murphy) is scaling back their bulk wire so I will see what they still have available.

 

 

 

 

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