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Author Topic: BSS FDS-340 Crossover Frequency Card Information?  (Read 8966 times)

ryansupak

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BSS FDS-340 Crossover Frequency Card Information?
« on: February 10, 2015, 12:56:40 AM »

Hi, I was wondering if anyone could point me in the direction of a table/diagram that shows how to change the crossover points in a BSS FDS-340 crossover. (For those that don't know, it has a few cards inside and you can change the resistors/capacitors on these cards to select the high pass/low pass frequency for a given output band.)

Anyway, I can say with certainty that the FDS-360 cards are NOT the same. There is a different amount of pins and the components are oriented differently. I have Googled like crazy for an FDS-340 manual and cannot find one. So...any help appreciated; I hoped maybe somebody could snap a few pics from a manual they had in a filing cabinet or something!

Thanks,
rs
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Keith Broughton

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Re: BSS FDS-340 Crossover Frequency Card Information?
« Reply #1 on: February 10, 2015, 08:39:06 AM »

Hi, I was wondering if anyone could point me in the direction of a table/diagram that shows how to change the crossover points in a BSS FDS-340 crossover. (For those that don't know, it has a few cards inside and you can change the resistors/capacitors on these cards to select the high pass/low pass frequency for a given output band.)

Anyway, I can say with certainty that the FDS-360 cards are NOT the same. There is a different amount of pins and the components are oriented differently. I have Googled like crazy for an FDS-340 manual and cannot find one. So...any help appreciated; I hoped maybe somebody could snap a few pics from a manual they had in a filing cabinet or something!

Thanks,
rs

I suspect the freq cards for the 340 and 360 are the same.
Check the chart in this manual...
http://bssaudio.com/product_downloads/User_Manuals/fds360um.pdf
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ryansupak

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Re: BSS FDS-340 Crossover Frequency Card Information?
« Reply #2 on: February 10, 2015, 12:00:03 PM »

Thanks for the reply.

No, the frequency cards are unfortunately not the same. (Also there are a few weird typos in the PDF version of that chart, which I only realized after looking at it for a long time).

rs
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Keith Broughton

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Re: BSS FDS-340 Crossover Frequency Card Information?
« Reply #3 on: February 11, 2015, 01:12:54 PM »

Thanks for the reply.

No, the frequency cards are unfortunately not the same. (Also there are a few weird typos in the PDF version of that chart, which I only realized after looking at it for a long time).

rs
Worth a try.
Contact the company directly and see if they can help.
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Chris Hindle

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Re: BSS FDS-340 Crossover Frequency Card Information?
« Reply #4 on: February 12, 2015, 08:22:43 AM »

I've got 360 manuals around somewhere. Geez, I think I pulled them out of service a good 20 years ago. But, you know us old sound dudes never throw away anything. Never saw a 340. If you say the cards are different, I guess I am of no use to you. Ours were customized for an Adamson MH-225 / B-218 rig.
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James Cotton

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Re: BSS FDS-340 Crossover Frequency Card Information?
« Reply #5 on: February 12, 2015, 08:50:18 AM »

Worth a try.
Contact the company directly and see if they can help.

Your best bet would be to contact George McKechnie at dba.
George was with BSS from 1984 to 2002 running the test and technical support departments.
What he doesn't know about BSS kit from that era isn't worth knowing.

http://www.dba-uk.co.uk/
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Riley Casey

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Re: BSS FDS-340 Crossover Frequency Card Information?
« Reply #6 on: February 12, 2015, 10:56:21 AM »

It's been a long time since I had any FDS340s in hand but  I do seem to remember that there was an identity between the component values for various frequencies in the R/C charts between the 340 & 360.  This would indicate that the circuit topology was the same and only the card form factor had changed.  If the component layout is different then it would probably take a fair amount of work to identify what's what, probably way more work than tracking down the user docs but if you do want a project you can probably user the values in the 360 chart.

Guy Morris

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Re: BSS FDS-340 Crossover Frequency Card Information?
« Reply #7 on: February 12, 2015, 12:45:30 PM »

I have some FDS 360 units and when purchased they just came with a preset card mine were labeled as x/o 250hz but I did not know you could do component value swaps on them!

I did come acoss the manual for the 360 only last year in a dusty file but if it is a different beast to the 340  then maybe no use.
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ryansupak

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Re: BSS FDS-340 Crossover Frequency Card Information?
« Reply #8 on: March 01, 2015, 02:35:15 PM »

Good people,

I got some info on this by calling a Nashville-based company called Creation Sound, who used to be the BSS Service Center for their region before BSS was sold. A man there said he lucked out and found this info on an old CD-ROM, as most of their paper documentation was taken out by a major flood a few years ago.

***

Firstly, here is the table that shows which values to use for which crossover frequency.

 FDS-320/340 and MCS-200 FREQUENCY CARD COMPONENT SELECTION                               
                                
             (and BSSO3B-MCS only)                   
                                
 Freq    R1A    R1B    R2A    R2B    C    CLA    CLB
                            
 50    43k    47k    82k    100k 100n 470n 470n
 60    36k    39k    75k    75k    100n 470n 470n
 63    33k    39k    47k    150k 100n 470n 470n
 70    16k    -    39k    180k 100n 470n 220n
 80    15k    220k 39k    100k 100n 470n 220n
 100    18k    30k    24k    330k 100n 470n -
 110    12k    68k    39k    43k    100n 470n -
 125    18k    18k    18k    -    100n 220n 220n
 150    7k5    -    15k    -    100n 220n 220n
 160    8k2    47k    15k    220k 100n 220n 220n
 180    6k2     -    13k    330k 100n 220n 220n
 200    18k    330k 39k    270k 33n    220n 100n
 220    18k    100k 100k 47k    33n    220n 47n
 250    15k    150k 27k    -    33n    220n -
 280    13k    180k 43k    56k    33n    220n -
 300    15k    47k    27k    150k 33n    220n -
 350    15k    27k    39k    39k    33n    100n 33n
 400    10k    56k    18k    330k 33n    100n 22n
 500    6k8     -    15k    150k 33n    100n 22n
 600    6k2    68k    15k    47k    33n    100n -
 800    39k    2k    39k    100k 10n    33n    33n
 1k0    12k    180k 47k    43k    10n    33n    22n
 1k2    10k    150k 27k    62k    10n    47n    -
 1k3    10k    68k    18k    470k 10n    47n    -
 1k5    7k5    -    15k    -    10n    47n    -
 1k6    8k2    47k    22k    39k    10n    47n    -
 2k0    8k2    18k    12k    180k 10n    47n    -
 2k5    18k    56k    27k    -    3n3    33n    -
 3k0    15k    47k    24k    470k 3n3    33n    4n7
 3k5    10k    330k 24k    100k 3n3    33n    -
 3k7    39k    12k    27k    56k    3n3    33n    -
 4k0    10k    56k    39k    30k    3n3    33n    -
 4k5    8k2    10k    18k    100k 3n3    33n    -
 5k0    6k8    -    18k    56k    3n3    33n    -
 5k5    6k2    -    13k    270k 3n3    22n    4n7
 6k0    6k2    68k    15k    47k    3n3    22n    4n7
 6k3    27k    6k8    27k    18k    3n3    22n    2n2
 6k5    22k    6k8    12k    82k    3n3    22n    -
 7k0    39k    5k6    13k    39k    3n3    22n    -
 7k5    10k    8k2    18k    18k    3n3    22n    -
 8k0    10k    7k5    10k    62k    3n3    22n    -
 8k5    4k7    27k    8k2    330k 3n3    15n    -
 9k0    3k9    120k 8k2    100k 3n3    15n    -
 9k5    15k    56k    82k    33k    1n0    15n    -
 10k0 15k    47k    43k    47k    1n0    15n    -
 12k0 12k    43k    27k    62k    1n0    10n    2n2
 15k0 7k5    -    15k    -    1n0    10n    2n2
 18k0 6k2    -    15k    82k    1n0    10n    -
 20k0 5k6    -    13k    82k    1n0    10n    -
 22k0 56k    5k6    12k    68k    1n0    10n    -
                            
                            
 All other frequencies can be obtained by suitable scaling of resistor values. Note R1a                           
 and R1b are in parallel as are R2a and R2b. CLa and CLb are also in parallel and a                           
 suitable value can be found by inspection. This component determines the limiter                           
 dynamic response, and is not as critical in value as the filter values are.                           
                            
 The above tables will produce 24dB per octave filter responses with corner frequency                           
 at  -6dB down when used with a BSS crossover system.                           
                            
 These values can also be use to produce 12dB per octave -3dB filters by removing                           
 the post limiter filter section. Please refer to your dealer or direct to the factory.                           
                            
 For 18dB per octave  -3dB filters please refer to your dealer or direct to the factory.                           
                            
 Other types of filters, mixed frequency overlaps, or any other arrangement can be                            
 obtained but please refer to factory for advice.                           

***

Using this chart, I was able to reverse-engineer how the component values relate to positions on the cards (so I would know what values to put where):

If an FDS 340 card is facing you, board connector pins down, and components side forward, there are (4x) vertical columns containing (6x) components each. Then, rightmost on the card, there is a 5th section of (3x) components arranged in a horizontal row.

Here is how the components on a card translate to what is on the chart you provided. The components are listed from leftmost section to rightmost section, listed from top to bottom. The fifth section is listed from left to right. The example I provide here contain the example values for a 1K2 card:

1K2 Card: (read from component side...lines 1-4 top to bottom...line 5 left to right)

Line1 ............
Cap 10n [C]
Res 10K [R1A]
Res 150K [R1B]
Cap 10n [C]
Res 27K [R2A]
Res 62K [R2B]

Line2 ............
Res 10K [R1A]
Res 150K [R1B]
Res 27K [R2A]
Res 62K [R2B]
Cap 10n [C]
Cap 10n [C]

Line3............
Cap 10n [C]
Cap 10n [C]
Res 10K [R1A]
Res 150K [R1B]
Cap 10n [C]
Cap 10n [C]

Line4............
Cap 10n [C]
Cap 10n [C]
Res 10K [R1A]
Res 150K [R1B]
Res 10K [R1A]
Res 150K [R1B]

Line5.............
Res 150K [R1B]
Res 10K [R1A]
Cap 47n [CLB]

Total Components Per Card.............
(6x) R1A
(6x) R1B
(2x) R2A
(2x) R2B
(10x) C
(1x) CLB

****

Hope this helps the next person seeking this info.
rs
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Keith Broughton

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Re: BSS FDS-340 Crossover Frequency Card Information?
« Reply #9 on: March 01, 2015, 03:47:20 PM »

Good find!
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Re: BSS FDS-340 Crossover Frequency Card Information?
« Reply #9 on: March 01, 2015, 03:47:20 PM »


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