Replacement Hi-Mid driver for Tecamp Puma 110 combo

[pete.young]

My Tecamp Puma 110 combo has developed an annoying buzz from the hi-mid 4" driver, so I think it is on the way to complete failure.

 

There are no identifying marks on the driver and nothing useful except '8Ohms' . I can't find a specification for the existing driver apart from some marketing speak: "The combos feature the new NTM-1 middle-high cone speaker with a Neodymium double magnet system. Working in a sealed enclosure it impresses with a low roll-off frequency and a very flat frequency response, thus delivering a smooth top end far beyond 10 kHz at astounding sound pressure levels."

 

I've tried a couple of emails to [email protected] but haven't had a response, so I don't have high hopes of either a replacement NTM-1 or the CT1 which they now fit.

 

I have found this B&C driver, which has a range of 110 - 8000 Hz which seems to be in the right range. https://www.bcspeakers.com/en/products/lf-driver/4/8/4NDF34

Would this be a suitable replacement driver, or can someone propose something better?

 

 

[Bill Fitzmaurice]

Post a picture of the original driver.

[pete.young]

I knew I should have done this before putting it back together.

 

That serial number string doesn't bring up anything useful in searches.

 

 

 

I just recalled that the original woofer was made for Tecamp by Sica, and I wonder if the hi-mid driver was too. It looks similar in spec to the 4 C 1,5 C P but I'm not sure where I can get one in the UK. https://sica.it/wp-content/uploads/2021/05/Z001920-1.pdf

[stevie]

It's not part of Sica's standard product range. I did a reverse Google Image search and came up with nothing. It looks very much like a cheap Chinese car audio chassis. It doesn't look like a neodymium driver, by the way.

 

@Bill Fitzmaurice might be able to suggest something, but it's difficult to do so without knowing how the system has been designed. I'd expect this to be a midrange driver with a higher efficiency than either the Sica or B&C drivers the OP mentioned.

 

Perhaps try phoning Eich or contacting one of their UK dealers.

[Bill Fitzmaurice]

That looks like a generic low end driver. The small dome indicates a small diameter voice coil. It's not neo, so I suspect a previous owner replaced it. That B&C you linked should be fine if it comes in 4 ohm, as would be  https://faitalpro.com/en/products/LF_Loudspeakers/product_details/index.php?id=401005101

[stevie]

I'd be wary of replacing an 8-ohm driver with a 4-ohm one. It will change the crossover frequency and you could end up with a 4-ohm cab. You also run the risk of dragging the impedance below 4 ohms and killing your amp. There are too many unknowns here. An original replacement driver shouldn't be expensive - if you can find one.

Edited June 3, 2024 by stevie

[Pea Turgh]

So the original blew, now the replacement is on its way out.  Maybe a problem somewhere else, too?  Could a duff component on the crossover be the original problem?

[Bill Fitzmaurice]

It could be a poorly designed crossover. It's common to cheap out on those.

[pete.young]

43 minutes ago, Pea Turgh said:

So the original blew, now the replacement is on its way out.  Maybe a problem somewhere else, too?  Could a duff component on the crossover be the original problem?

This is the original. As far as I know, I'm the only owner of this combo.

 

Ah, I see what you mean. It's possible that the original blew and was replaced before I bought the combo, but it was supposed to be new at the time and wasn't described as B Stock. I can't explain how they wouldn't have fitted an original part.  If it's been in there all the time I've owned it, it's lasted 15 years, if I get another 15 out of the replacement I'll be 81 and long-retired from gigging!

Edited June 3, 2024 by pete.young
Penny dropping.

[pete.young]

22 hours ago, Bill Fitzmaurice said:

That looks like a generic low end driver. The small dome indicates a small diameter voice coil. It's not neo, so I suspect a previous owner replaced it. That B&C you linked should be fine if it comes in 4 ohm, as would be  https://faitalpro.com/en/products/LF_Loudspeakers/product_details/index.php?id=401005101

 

As far as I know, I am the only owner of this combo. I bought it in October 2009 when guitarguitar gave up the distributorship. A lot of basschatters bought discounted Tecamp gear at that time.  Unless it was a return before my ownership or gearformusic fitted it, I don't know how this driver got in there.

 

The only people who have worked on this combo since I bought it are Tecamp themselves, who replaced the woofer when it failed in 2011. It's been fine since then, until a few weeks ago.

 

Thanks everyone for the assistance and @Bill Fitzmauricefor the link to that Faital driver, Blue Aran have them in stock so I should be able to get one without any trouble.

Edited June 4, 2024 by pete.young
guitarguitar, not gearformusic

[Bill Fitzmaurice]

It appears to be a replacement because it's not neo, and the cone is polypropylene, which is typical of auto sound drivers. For that matter so is the 3 ohm impedance, and the thin metal frame. The soldered connections are also unusual, they usually use spades, and those of different sizes to insure the polarity. Of course it wouldn't be the first time that the advertising didn't match up with reality. 

Edited June 3, 2024 by Bill Fitzmaurice

[stevie]

It could be 3 ohms impedance but it's also possible that it's 8 and that part of the number has rubbed off.

[pete.young]

I thought I'd better take the woofer out and have a look at the crossover. Turns out that there isn't a crossover as such: the mid driver is parallel-ed off the woofer and has a 4.7 µF capacitor in the positive line. Picture attached. I haven't a clue what effect that has, I'm hoping someone here can enlighten me.

 

I think it's a partially rubbed-out 8Ohm rather than 3, which would match the woofer impedence.

 

 

 

[stevie]

I'll let Bill comment on this. 😁

[Hellzero]

Still the auto sound design here with that filtering cap. And it's typical from Eich really poor design. I had to work on a few Eich designs (I mean Tech, Tecamp and Eich by this) and they are all made on the cheap. 🫣🤦

[Bill Fitzmaurice]

1 hour ago, pete.young said:

I thought I'd better take the woofer out and have a look at the crossover. Turns out that there isn't a crossover as such: the mid driver is parallel-ed off the woofer and has a 4.7 µF capacitor in the positive line. Picture attached. I haven't a clue what effect that has, I'm hoping someone here can enlighten me.

That's the problem. The protection it offers is almost nil. It also has a knee frequency that's at least an octave too high, around 4kHz, so it might as well be a tweeter. A proper crossover at 800 to 1.2 kHz would give a much better result.

[pete.young]

So looking on the bright side, an actual crossover and a decent hi-mid driver could be a huge improvement. If anyone can recommend a crossover product or a circuit I will fit one. Thanks once again to @Bill Fitzmaurice and @stevie for sharing your knowledge. It is much appreciated.

[Bill Fitzmaurice]

I can provide that if you're comfortable building it.

[pete.young]

12 hours ago, Bill Fitzmaurice said:

I can provide that if you're comfortable building it.

 Yes please. I have built a few effects pedals so I am confident I can do this.

[LeftyJ]

Paging @pepe1001

 

Edit:  Works for Eich, but hasn't been here in almost 3 years. Maybe not so effective. 

Edited June 4, 2024 by LeftyJ

[Bill Fitzmaurice]

I suggest you use the 8 ohm version of the Faital. These are schematics for 800 Hz 8 ohm high pass and low pass filters for midrange and woofer respectively. The capacitors are poly or mylar film, rated for at least 100 volts. The coils are solid core, of the smallest available wire gauge with no more than 0.4 ohms DCR (resistance). You can find these at Blue Aran. A plus/minus 10% tolerance of the component values is permissible.

 

Build each filter on its own thin plywood board. Secure the components with hot melt glue and plastic zip ties to they can’t vibrate loose. All connections are soldered.

 

To test for correct polarity download a pink noise generator to your laptop. Get this app on your phone:
https://play.google.com/store/apps/details?id=com.dom.audioanalyzer
Set it to Spectrum Analyzer, 1/3 octave, C Weighting, Slow Response.

Wire the low pass filter to the woofer. Place the speaker face up. Connect the high pass leads to the midrange but don’t screw it down yet. Connect the laptop to your amp, play the pink noise. Look at the response in the region of 800 Hz. There should be no response dip. If there is reverse the leads to the midrange and test again. That should eliminate any dip.

 

 

Edited June 4, 2024 by Bill Fitzmaurice

[Bill Fitzmaurice]

BTW, why 800Hz? That's where the beam pattern of the woofer begins to narrow. The reason why mids are smaller than woofers and tweeters are smaller than mids isn't just response, it's also dispersion. The smaller the cone the wider the dispersion as frequency increases. The Faital is rated for 60w at 100Hz, but the power density of music halves with each octave increase in frequency, so with an 800 Hz crossover it should take 240w thermal with 3dB headroom. Mechanically it can take at least twice that.

[pete.young]

I'm pleased to say that there is a happy ending to this tale. I replaced the driver with a Faital 4FE32. I was having difficulty sourcing capacitors for a reasonable price so I ended up going with an 800Hz crossover from Blue Aran. The difference is like night and day - not only has the annoying buzz gone, but the sound is much improved and there is much more clarity in the higher frequency. Thanks everyone for your suggestions.

 

I did recieve an email from Eich, asking me to send photos of the driver because "we are unsure what is in there." No response so far to the email I sent back.

[BassAdder60]

That makes a satisfying read and good news you fixed it and for the better it seams 

 

I have a new EICH T900 amp which is very nice but EICH are terrible replying to emails or FB messages 

 

Great amps but terrible after sales support it would appear. 

 

Edited June 22, 2024 by BassAdder60

[Phil Starr]

That 4" driver is shocking but It's really good to see you have an outcome that has given you a better speaker. Kudos to @Bill Fitzmaurice for his help to you.