Help Figuring Out Tannoy Autograph Mini crossover

[Zaiden]

Hey Zaiden,

Did you ever get around to making the crossovers?

Not yet! Life's been pretty busy as of late.

If I do get around to it, I think I'll probably replicate the older Tannoy Autograph Mini crossover, because that's the one we've had the most comprehensive information about.

 

[Howard B]

Ok i might be able to get access to the crossover in a couple weeks, had a pair i sold to client and realised how much i loved the drivers after they left me and didnt take the crossovers out.

What are the specifics you didn't find out so i know exactly what im looking for?
I might need to buy a good lcr meter then i could measure the values.

 

[Zaiden]

Ok i might be able to get access to the crossover in a couple weeks, had a pair i sold to client and realised how much i loved the drivers after they left me and didnt take the crossovers out.

What are the specifics you didn't find out so i know exactly what im looking for?
I might need to buy a good lcr meter then i could measure the values.

Oh maaaaaaaaaaaaan. That would be incredible!

For the Autograph Prestige Mini, the ones I'm missing now are information on the top left L1 inductor and top right L2 iron core inductors, as well as specs for the C4 Richey A18C.

I have a feeling it should say the values on the components themselves, just I can't get the existing photos zoomed in enough to tell.

For the Autograph Mini, it would be the upper half of rdale's photo of the crossover, as well as any inductors that do not have written values on them.

 

[Howard B]

Ive ordered an LCR meter which ill test before the job, so hopefully will get a full list.

Warmest,

 

[Zaiden]

Ive ordered an LCR meter which ill test before the job, so hopefully will get a full list.

Warmest,

 

[Howard B]

tested the meter bits its a cheapish one and its giving readings 5-10% off but that may just be the tolerance in the components...

Amazon product

 

[Zaiden]

tested the meter bits its a cheapish one and its giving readings 5-10% off but that may just be the tolerance in the components...

Amazon product

Couldn't get back sooner because I was away for the weekend. That's not a problem, and I would be happy to hear how components measure because it gives me something to figure stuff out with.

 

[Howard B]

Actually got it working now within 2%ish, please send the values you have so i know if anythings off while running through, i wont have long with them.

 

[Zaiden]

Actually got it working now within 2%ish, please send the values you have so i know if anythings off while running through, i wont have long with them.

These are the values I got for the Prestige Autograph Mini

Capacitors: C2: 100V 200uf NP(G) / C1: 100V 15uf NP(G) / MPT 2.5 uf J 100V / MPT 2.2 uf J 100V

Ceramic Resistors: R1 and R2: 5W 1R J / R3: 5W 3.9R J / R4: 10W 10R J

Air Core Inductor: L3: 0.5mH (Bottom left) | L4: 0.15mH (bottom right)

Only ones missing now are information on the top left and top right iron core inductors, as well as specs for the C4 Richey A18C

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If you have the Autograph Mini crossover on hand, I do not have enough information for any of the crossover schematics in that - although from what little I've seen there's a lot of similarities with the Prestige edition. I was primarily deriving values of the Prestige edition by reading them off the images. What I'm lacking is especially the upper section as the picture we have is from one that is still attached to the driver, so wasn't pulled out all the way.

 

[Fatmarley]

It's also important to have the inductor DCR.

 

[bencat]

Okay give up what is DCR ?

 

[Lawrence001]

Okay give up what is DCR ?

DC resistance? It's also helpful to know the ESR of caps if you don't replace like for like as it can also change the crossover values although maybe not as much. That's effective series resistance I believe.

 

[Fatmarley]

DC resistance? It's also helpful to know the ESR of caps if you don't replace like for like as it can also change the crossover values although maybe not as much. That's effective series resistance I believe.

Yes, DC resistance.

As for ESR, I would replace like for like - Electrolytic for electrolytic, and film for film. Not that you want to try and fit a 200uf film cap in those tiny speakers.

 

[Zaiden]

Been a new development.

Found a picture which has given me the value on the top right ferrite core inductor as 6.0mH

As for DCR I'd imagine generic old Chinese stuff would work given that's what Tannoy seems to have used. We'll have to see!

 

[Zaiden]

Been a new development.

Found a picture which has given me the value on the top right ferrite core inductor as 6.0mH

As for DCR I'd imagine generic old Chinese stuff would work given that's what Tannoy seems to have used. We'll have to see!

The person on Facebook kindly provided me a picture of the label for the top left iron core capacitor - 1.0mh!

With that I'm only missing one component to figure out the whole crossover - the identity of the C4: A18C Richey Capacitor. I think this single component could potentially be reverse engineered given the known crossover value point is 2.3khz.

 

[Zaiden]

I've unscrewed the bottoms of both the right and left speakers, but the crossovers won't come out fully - it feels like there are some wires which I can't see. Here is a picture with some of the capacitor and resistor values:

The values of the inductors aren't printed, but they may be on the reverse of the circuit board. I might be able to use a mirror and a torch to see the values of the yellow capacitor at the end of the board. The resistor at the top right is labelled '5W 1RJ'.

Actually looking at picture of the circuit board you've posted, it is a different design. I have the mk 1 autograph minis, and it looks like they redid the design for the mk 2 version.

Using deduction based on this image which was kindly provided to me, I would wager an educated guess that the final unknown capacitor should have a value of 15uf 100V as well, as there are two of them in a similar arrangement on the crossover for the original Tannoy Autograph Mini.

I think I'm about ready to proceed - just need to figure out how the circuit would be arranged to provide a 2.3khz crossover point.

 

[Beobloke]

The person on Facebook kindly provided me a picture of the label for the top left iron core capacitor - 1.0mh!

With that I'm only missing one component to figure out the whole crossover - the identity of the C4: A18C Richey Capacitor. I think this single component could potentially be reverse engineered given the known crossover value point is 2.3khz.

De-solder it. The value will be printed underneath.

 

[Zaiden]

De-solder it. The value will be printed underneath.

I don't think I'd be able to convince the person on Facebook to do that.

On another note, would I be able to figure out the crossover circuit using educated guesses?

Or would it only be possible by seeing it for what it is by removing the binding post panel on the back?

 

[Beobloke]

I don't think I'd be able to convince the person on Facebook to do that.

On another note, would I be able to figure out the crossover circuit using educated guesses?

Or would it only be possible by seeing it for what it is by removing the binding post panel on the back?

Ah, sorry - didn't realise they weren't yours!

However, the words "educated guess" and "crossover design" never end well.

 

[Zaiden]

The words "educated guess" and "crossover design" never end well.

Fair point. Would similar Tannoy crossover circuit schematics (e.g. XT Mini) help or not really?