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Multi-Way Conventional loudspeakers with crossovers

Refurbishing PSB Image 6Ts - sanity check!
Refurbishing PSB Image 6Ts - sanity check!
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Old 15th April 2019, 11:20 PM   #31
Cori is offline Cori  Australia
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Quote:
The original crossover (or a replacement stock one) will have to be modified in all cases
Yes I realised my stupidity on this comment last night in bed. Of course the crossover will have to be modified because I can't get the identical drivers as in the original cab, and the response will be different. I don't know what I was thinking.

I think this is good advice. I'll gather my thoughts and post a plan for the way forward in the next day. I'm really very grateful for all the help!

Last edited by Cori; 15th April 2019 at 11:22 PM. Reason: typo
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Old 16th April 2019, 11:33 AM   #32
Cori is offline Cori  Australia
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OK here's the plan.

1. Order the following parts from Parts Express or similar
  • 2 x BC25SC08-04 (4 Ohm) tweeters
  • 2 x Resistor 22 Ohm
  • 2 x Capacitor 33μF
  • 2 x Capacitor 3.9μF
2. Dismantle the crossover, take photographs. Clean up with isopropyl.

3. Solder the new components on to the board.

4. Reassemble crossover and test with multimeter.

5. Soft install crossover and connect to drivers. Test. Jump for joy if it works.

6. Repeat for second speaker.

My only question is whether it would be worth my trying to find 8 Ohm tweeters rather than the 4 Ohm versions listed above. Otherwise, I think I'm good to go!
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Old 16th April 2019, 12:07 PM   #33
Cori is offline Cori  Australia
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Edit: Resistor 2.2 Ohms, not 22!

Oh, but what wattage?
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Old 17th April 2019, 02:58 AM   #34
DonVK is offline DonVK  Canada
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Default Suggested parts 3way mod

A suggested parts list, based on schematic V4 post #25, making a 3way using Jaycar drivers. The midrange driver does not require a ported cabinet and you can seal the pipe at inside opening (paper towel plug wrapped in plastic).

R2=2.2R (2.2 ohm)
this 5w or the 10w below : 2.2 Ohm 5 Watt Wire Wound Resistor | Jaycar Electronics
R3=R4= 1.5R or 2.2ohm and Jaycar does not have 1.5R in 10W
only Jaycar option : 2.2 Ohm 10 Watt Wire Wound Resistor | Jaycar Electronics

C2=3.3uF bipolar 100v
better : 3.3uF 100V Electrolytic Crossover Capacitor | Jaycar Electronics
acceptable : 3.3uF 50V Bipolar Electrolytic Capacitor | Jaycar Electronics

C3=33uF bipolar 100v,
better : 33uF 100V Electrolytic Crossover Capacitor | Jaycar Electronics
acceptable : https://www.jaycar.com.au/33uf-50v-b...citor/p/RY6818


Recommended to use quick disconnect spade M+F same size as your new speakers or crossover. Like these, but check your sizes.
https://www.jaycar.com.au/female-spa...-pk-8/p/PT4507
https://www.jaycar.com.au/male-spade-red-pk-8/p/PT4509

The modifications can be done by inserting the mod resistor or cap with M/F spade lugs between the a) speaker wire and crossover board or b) speaker wire and speaker terminal. This allows you to make adjustments easily when you listen (or measure preferred) and need to correct a problem. When you are happy then try to find room on the board and make it more permanent if you want.

Last edited by DonVK; 17th April 2019 at 03:03 AM. Reason: missed tweeter selection - update schemtic needed
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Old 17th April 2019, 03:34 AM   #35
DonVK is offline DonVK  Canada
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Default schematic v5

Well, I missed by edit window so I'll add the updates here. I noticed you want the 4 ohm tweeter. So I included a 4 ohm tweeter in a quick sim using a Dayton RST28a-4 to see the effect. Your BC25SC08-04 seems like it's a bit more sensitive than RST28, and you may decide to tone it down once you listen to it. The speaker impedance is still good.

R2 = 4.7ohm 4.7 Ohm 5 Watt Wire Wound Resistor | Jaycar Electronics
Attached Images
File Type: jpg PSBimage6T_XO_v5.jpg (328.5 KB, 12 views)

Last edited by DonVK; 17th April 2019 at 03:36 AM. Reason: typo
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Old 20th April 2019, 12:31 AM   #36
Cori is offline Cori  Australia
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Don thank you so much for your careful and thoughtful work here - this will be very helpful to me. Thank you also for the M/F spade lug tip! I'm about to go shopping (the tweeter will take longer to arrive, from sunny Springboro, Ohio). I'll report back with updates.
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