Starting a project with a pair of Thiel CS3.5 cabinets

[Thannytoes]

I picked up a pair of Thiel CS 3.5 cabinets from craigslist for $135. They came with the crossovers, but all of the drivers were parted-out. Also, I just found out that these speakers originally came with an external bass equalizer, which I don't have. (I've emailed the seller but I am not hopeful.)

I need to find appropriate replacement drivers. The Dayton Reference line is looking good and they will fit perfectly in the original holes. The speakers were originally 4 ohm, but I wouldn't mind making them 8 ohm. (Is this ok with the original crossovers?)

I'm looking at:
Woofer: Dayton RS270-8
Mid: Dayton RS125-8 (This is a 5" instead of a 4" like the original, but it fits the hole perfectly.)
Tweeter: Dayton RS28F-4

Are there any concerns about the original crossover (400Hz, 3kHz.) working well with these drivers? If I don't have the equalizer, would there be an issue? Any way around it?

I'm a hobbyist and not a true expert, thanks for any and all advice!

Here are the original specs:

Description: Three-way, sealed-box loudspeaker with line-level bass equalizer.

Drive-units: 1" soft-dome tweeter, 4" paper-cone midrange unit, 10" plastic-cone woofer.

Crossover frequencies: 400Hz, 3kHz.

Frequency response: 20Hz–20kHz ±2dB. Sensitivity: 88dB/W/m.

Nominal impedance: 4 ohms. Minimum amplifier power: 40W.

Dimensions: 41" H by 13" W by 13" D. Weight: 75 lbs each.

Internal volume is about 2085 cubic inches.

[Thannytoes]

Re: Starting a project with a pair of Thiel CS3.5 cabinets

Another pic..

[Pete Schumacher]

Re: Starting a project with a pair of Thiel CS3.5 cabinets

I picked up a pair of Thiel CS 3.5 cabinets from craigslist for $135. They came with the crossovers, but all of the drivers were parted-out. Also, I just found out that these speakers originally came with an external bass equalizer, which I don't have. (I've emailed the seller but I am not hopeful.)

I need to find appropriate replacement drivers. The Dayton Reference line is looking good and they will fit perfectly in the original holes. The speakers were originally 4 ohm, but I wouldn't mind making them 8 ohm. (Is this ok with the original crossovers?)

I'm looking at:
Woofer: Dayton RS270-8
Mid: Dayton RS125-8 (This is a 5" instead of a 4" like the original, but it fits the hole perfectly.)
Tweeter: Dayton RS28F-4

Are there any concerns about the original crossover (400Hz, 3kHz.) working well with these drivers? If I don't have the equalizer, would there be an issue? Any way around it?

I'm a hobbyist and not a true expert, thanks for any and all advice!

Here are the original specs:

Description: Three-way, sealed-box loudspeaker with line-level bass equalizer.

Drive-units: 1" soft-dome tweeter, 4" paper-cone midrange unit, 10" plastic-cone woofer.

Crossover frequencies: 400Hz, 3kHz.

Frequency response: 20Hz–20kHz ±2dB. Sensitivity: 88dB/W/m.

Nominal impedance: 4 ohms. Minimum amplifier power: 40W.

Dimensions: 41" H by 13" W by 13" D. Weight: 75 lbs each.

Internal volume is about 2085 cubic inches.

Crossover won't work with the drivers. They're very specific to the units they were designed for.

However, you could part out the XOs and perhaps use them in the new XOs.

For those drivers, I'd shoot for 350 and 2000.

[DE Focht]

Re: Starting a project with a pair of Thiel CS3.5 cabinets

If you can fit it in the budget, use an active crossover for the speaker.

The PE reference speakers will make an excellent replacement and the 3.5's box is excellent, but you may want to damp the rear panel a little more.

The active crossover will allow you to take advantage of most of the features made available by the CS box.

The EQ was a bandaid for a woofer that played significantly in the midrange and needed to be controlled and extended in the bass to balance the speakers sound....plus a basic room eq.

[johnastockman]

Re: Starting a project with a pair of Thiel CS3.5 cabinets

I picked up a pair of Thiel CS 3.5 cabinets from craigslist for $135. They came with the crossovers, but all of the drivers were parted-out. Also, I just found out that these speakers originally came with an external bass equalizer, which I don't have. (I've emailed the seller but I am not hopeful.)

I need to find appropriate replacement drivers. The Dayton Reference line is looking good and they will fit perfectly in the original holes. The speakers were originally 4 ohm, but I wouldn't mind making them 8 ohm. (Is this ok with the original crossovers?)

I'm looking at:
Woofer: Dayton RS270-8
Mid: Dayton RS125-8 (This is a 5" instead of a 4" like the original, but it fits the hole perfectly.)
Tweeter: Dayton RS28F-4

Are there any concerns about the original crossover (400Hz, 3kHz.) working well with these drivers? If I don't have the equalizer, would there be an issue? Any way around it?

I'm a hobbyist and not a true expert, thanks for any and all advice!

Here are the original specs:

Description: Three-way, sealed-box loudspeaker with line-level bass equalizer.

Drive-units: 1" soft-dome tweeter, 4" paper-cone midrange unit, 10" plastic-cone woofer.

Crossover frequencies: 400Hz, 3kHz.

Frequency response: 20Hz–20kHz ±2dB. Sensitivity: 88dB/W/m.

Nominal impedance: 4 ohms. Minimum amplifier power: 40W.

Dimensions: 41" H by 13" W by 13" D. Weight: 75 lbs each.

Internal volume is about 2085 cubic inches.

Unfortunately, unless you can get the OEM drivers, the stock XO will not work for anything other than the original drivers. There's way too many variables at work and the different characteristics and performance specs between drivers won't allow any drop-in solutions. Theil is one of very few commercial designs that I find to be very well designed and with superb SQ. A lot of designing expertise went into those, especially with the stock XO. Maybe try to source some OEM drivers? Theil might be able to assist with that. Otherwise, you can try to find a proven DIY design that is similar in configuration, or someone here might be able to work up a XO that will work with those drivers you listed. Theil also makes some excellent cabinets, so keeping them is a good idea. Nice find! A well-designed XO will make or break a speaker. Textbook formulas and pre-made XO's will lead to a SQ that you won't enjoy listening to. Good luck and let us know if you have any other questions or concerns.

John A.