Tannoy Dual Concentric DC1000 big mid range hump in response. Characteristic?

bondospecial

Active Member
Hello all. My newly acquired Tannoy DC1000's work well but sound like they have a big midrange peak right in the vocal range. I measured all caps to be around +10% from nominal and I also measure a +6db peak in the 900-1200 hz range which falls back to nominal by 1500 hz.

Question: Did these Tannoy 8" dual concentrics w/ horn loaded HF units have this big midrange peak from the factory, or were they much flatter and I need to repair the crossovers?

Would the caps being close to +10% from nominal move the crossover point higher or lower from the factory crossover point?

Here they are. I paid several hundred bucks for these things, I know I'm probably insane and I am probably going to single handedly inflate the market on these but I was really curious what a Tannoy dual concentric speaker sounded like and how they would compare against my similar sized DM602s and Q60s. And Tannoy DC speakers are not exactly common in the US so when I saw these on Ebay I got excited and bought them.

I re hot-glued the components in place while I was in there measuring cap values and re soldering. Tannoy's circa 1990 hot glue had all failed when I got them. Not the most secure factory mounting of the components...
 
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Bump. I edited my first post to make it shorter and more to the point, and to pose a question towards the beginning rather than burying it. Sorry I tend to ramble. -Steve
 
Your crossovers use non-polarized electrolytic caps. These are the cheapest possible caps for crossover use and don't age well. Replace them with some good film types, such as Solens, or paper in oil types and things will most likely be MUCH better.
 
Hello, thanks! I will do just that. Excuse my noob-ishness, but can anyone tell me what order this crossover appears to be, so I can play with #s and figure out whether the +10% cap values would make the crossover point too low or too high?
 
Thanks! Apart from the resistors, capacitors, and inductors that I can identify from looking at my pic, can you please tell me what type of component the yellow part is that is on the middle left and appears to have a "PW" on it which reads upside down in the pic?
 
That looks like it's POSSIBLY a film type cap. If you scrape off some of the hot glue very carefully you might be able to get the value off of it. Or, you can take a look at the other crossover. Most likely Tannoy combined caps of different values to get the precise value they wanted.
 
Done, here it is in its less-gluey glory. PW1U5J160...currently googling to figure out what this is.

It is measuring 1.58 microfarads so it does appear to be a capacitor. Should I replace this too when I replace the other caps?

Tannoy-Crossovers-001-XL.jpg
 
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Looks like it's a 1.5uF, 160 volt capacitor. Due to the fact that it's 20 years old and we have much better capacitors available today for reasonable cost, I would say without a doubt go ahead and replace it also. Does your tester also measure ESR?
 
Trying to trace the wiring from the picture, I'm coming up with something different. The low pass side (right side in your picture) looks to be a standard 2nd order with a zobel for the woofer.

The tweeter side looks like the input goes through the yellow cap, then the resistor (padding the level to match the woofer) to the output with the cap on the top left going into the coil on the bottom left to ground to form a trap (notch filter) in parallel with the tweeter.

According to this brochure the crossover point is supposed to be 2.3kHz. Things would have to be waaaay out of spec for that to be causing a hump in the 900-1200 range.
 
Trying to trace the wiring from the picture, I'm coming up with something different. The low pass side (right side in your picture) looks to be a standard 2nd order with a zobel for the woofer.

That must be what they meant by "heavily damped first order" on the woofer section.
 
I have no idea what they meant, just what I'm seeing on that circuit. It sure looks like the woofer input goes through the coil to a junction of capacitor, resistor, and output lead to woofer. The first cap looks to go to ground, the resistor goes to the other cap and to ground. The inductor in series and cap in parallel would be a 2nd order crossover and the resistor and cap in series that is in parallel with the woofer would be the Zobel.
 
Thanks for the literature. Would the crossover function the same with respect to the tweeter if I disconnect the bi-wiring jumpers and power only the tweeter, then test to see if it is outputting significantly below its crossover point? Or would removing the load of the woofer from the crossover make the tweeter side of the network behave differently?

Here are links to much larger pictures of the crossover network

http://bondospecial.smugmug.com/House/Steve-room/i-M2xtmX8/0/O/Tannoys-007.jpg

http://bondospecial.smugmug.com/House/Steve-room/i-vxXJjD2/0/O/Tannoys-008.jpg

Thanks!

Steve
 
I have no idea what they meant, just what I'm seeing on that circuit. It sure looks like the woofer input goes through the coil to a junction of capacitor, resistor, and output lead to woofer. The first cap looks to go to ground, the resistor goes to the other cap and to ground. The inductor in series and cap in parallel would be a 2nd order crossover and the resistor and cap in series that is in parallel with the woofer would be the Zobel.

I found an old review of these speakers and the author described the crossover in the manner I posted previously. However, I think you're correct in your description. Indeed, I'm betting Tannoy called the Zobel network "heavily damped".....It sounds better!
 
Two things to check:

First off, what kind of, and how much, stuffing is in the cabinets? Not having the proper lining in the cabinet, can cause standing waves... which could do what you're experiencing.

Secondly, I'd check the bond of the surround to the cone on both. A compromised glue joint there can wreak havoc with the frequency range mentioned (around 1000-1500 Hz)...

Regards,
Gordon.
 
Thanks for the literature. Would the crossover function the same with respect to the tweeter if I disconnect the bi-wiring jumpers and power only the tweeter, then test to see if it is outputting significantly below its crossover point? Or would removing the load of the woofer from the crossover make the tweeter side of the network behave differently?

You should be fine doing that. That's what the separate inputs are for.
 
I have the same speakers but no crossover. It is helpful for me to watch the jpegs, but I cannot read the values of the high pass cap and resistor. Is anybody able to draw a schematic?

Thanks, Gero
 
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