605-ALTEC N-1600-C Crossover help!!
Hi to all,
i have a pair of 605a altec speaker with the n-1600-c crossover.
The problem is that someone "modified" the crossover by taken out the hf-attenuator.
So what i have in the crossoverbox is a 12db slope (1mh+20uf) for the woofer and a 6db slope (5ohm+5,3uf+4ohm) for the tweeter.
Do have someone the original schematic or can advice me to complete the hf section?
Or,what crossover do you use with your 605?
Thank you very much,
frank
1 Attachment(s)
Type B_Installment__Series_Crossover_#1
Hi Frank
Well here's what I think your crossover does based on your latest info.
( I would love to actually measure those components - that way I might really have a clue as to what's needed ! )
I seems the circuit design is qute a hybrid. Most of it is acting in a series crossover topology . But that single 5.3 uf capacitor isn't part of the series circuit. It's acting in the "normal" manner as a high-pass filter. It's actual turnover frequency is likely in the 1600 hz area - but I need to know more about the AC impedance curve of the compression driver to really "know" that .
The 5 ohm resistor "pads" the driver a little bit but obviously not nearly enough. Together with 16 ohm value ( just guessing ) of your compression driver in the crossover area they form the 21 ohms that my little Crossover Calculator used as the working impedance for the HF section .
The 15 ohms for the woofer vale at the crossover frequency is just a "convenient" guess for the calculators sake .
Here's a jpg of your circuit as I understand it .
regards <> Earl K
1 Attachment(s)
Type B_Installment__Series_Crossover_#2
Hi Frank
Here's what I believe is a workable solution.
Remove that 5 ohm resistor and wire in one 8 ohm Lpad into it's place - placed ( according to my included jpg). I've never wired a Lpad into a series crossover circuit before so I spent sometime this afternoon checking out where that Ground/ Drain-Wire works best. Wire it in as I have shown on the jpeg. If you are tempted to attach the ground/drain, say to the standard ground side of the circuit ( as I was ), it does quite bizarre things . Everything is fine " full-up" but as you attenute or turndown the tweeter - the "self-balancing" nature of this circuit type rises up and bites one in the proverbial behind: :biting:
- Frequencies below the HF cutoff are actually significantly BOOSTED into the compression driver at full Lpad attenuation. :no: :scold:
This would of course, drastically shorten the lifespan of the diaphragm and it really thows the spectral balance out of whack when the Lpad is used in the middle of it's rotation area .
The position I've shown gives stable attenuation without moving the crossover point ( blasted self-balancing circuits !)
If it was my compresson driver - I'd play around with the value of that 5.3 uf capacitor. Making it smaller has the "realized" effect of slowing a drivers topend roll-off by starting its' highpassing action at a higher frequency. I'd play around with values between 3 uf to the stock 5.3 uf value . Because this alters the balance of "Midrange to HF" frequencies you would have to do this ( if at all ) to suit your own particular musical tastes .
Here's the jpg
If anyone out there sees a "train-wreck" occuring here, please speak up.
( Afterall - I electronically crossover everything - so what do I really KNOW ? ) :yes:
regards <>Earl K :)
1 Attachment(s)
Softwares'Optimal Damping ( values )
Hi Frank
Here's the pic as promised with a damping factor of .707 . This is what the software defaults to when opened up. The suggested LC values appear in the picture.
regards <> Earl K