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Old 29th July 2009, 02:37 PM   #1
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Default Brines FT-1600 Mk2 Build

Hi there

I have almost finished building a pair of Bob’s FT-1600 Mk2 speakers. In preparation I decided to wire up an inductor and a resistor to one of my FE167E drive units.

When I turn on the amp the cone slowly moves back and holds its position, then plays music. When I turn the amp off the cone returns to its normal position. Is this ok, or is it an indication the driver is wired out of phase?

Here is a sketch of the wiring…

Click the image to open in full size.

Thanks

Richard
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Old 29th July 2009, 03:56 PM   #2
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Hi Richard

looks like there might be some dc on the output. If you have a dmm you could set it on low dc volts and measure whats across the speaker terminals at idle. if possible measure both both speakers and report back.

its best not to have any dc on your amp output, but sometimes it can be found in small amounts.

Ed
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Old 29th July 2009, 03:58 PM   #3
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You have wired the BSC filter correctly. What I suspect is that your amplifier is putting out a DC offset. Try another amplifier and report back.

Bob
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Old 29th July 2009, 04:00 PM   #4
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Quote:
Originally posted by vitalstates
Hi Richard

looks like there might be some dc on the output. If you have a dmm you could set it on low dc volts and measure whats across the speaker terminals at idle. if possible measure both both speakers and report back.

its best not to have any dc on your amp output, but sometimes it can be found in small amounts.

Ed

Hi

I measured for dc offset a little while a go and only had about 50mv per channel. I'll check again!

Thanks

Richard
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Old 29th July 2009, 04:14 PM   #5
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OK, here are the readings

Right Channel

- Power on peaks for a split second at 194mV
- Idles at 15mV
- Power off peaks for a split second at 122mV

Left Channel

- Power on peaks for a split second at 189mV
- Idles at 19mV
- Power off peaks for a split second at 122mV

The amp has no source or speakers connected.

Richard
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Old 29th July 2009, 07:56 PM   #6
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Quote:
Originally posted by Tripmaster
OK, here are the readings


The amp has no source or speakers connected.

Richard
ideally need to measure with a load, i.e with speakers connected, or better with a power resistor if the amp is suspect.........

anyway, it looks like you have some dc on the output, which is not the best way to go......I think I would try another amp as Bob suggests.

Ed
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Old 29th July 2009, 08:25 PM   #7
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Quote:
Originally posted by vitalstates


ideally need to measure with a load, i.e with speakers connected, or better with a power resistor if the amp is suspect.........

anyway, it looks like you have some dc on the output, which is not the best way to go......I think I would try another amp as Bob suggests.

Ed

Hi Ed

Duh, I forgot about that! I suppose I could use one of the 6ohm speaker resistors between positive and ground for each channel.

I have connected an 8ohm speaker to each channel and here are the readings again.

Right Channel

- Power on peaks for a split second at 128mV
- Idles at 14.6mV
- Power off peaks for a split second at 133mV*

Left Channel

- Power on peaks for a split second at 40mV
- Idles at 20mV
- Power off peaks for a split second at 120mV

I like your amp reviews on your website BTW.

Richard
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Old 29th July 2009, 08:31 PM   #8
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Hi Bob

Is there a reason for using silicon sealant to fix the supra baffle to cabinet, rather than the flexible adhesive used to attach the cement board? And do you avoid applying Danish oil to the veneer behind the s.baffle?

Thanks

Richard
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Old 30th July 2009, 01:24 AM   #9
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Quote:
Originally posted by Tripmaster
Hi Bob

Is there a reason for using silicon sealant to fix the supra baffle to cabinet, rather than the flexible adhesive used to attach the cement board?

If you use Liquid Nails to attach the supra baffle to the baffle and it oozes out onto the baffle, you will find it next to impossible to get the NL off of the baffle without screwing up the finish. If you use clear silicon seal, you can correct the error with no damage. Really, just a safety measure. One of those little 6" tubes should be enough.


Quote:
And do you avoid applying Danish oil to the veneer behind the s.baffle?

Finish the entire baffle. The silicone seal sticks to the finish just fine.

Bob
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Old 30th July 2009, 10:47 AM   #10
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Hello

I have three amps, an Incatech Claymore, Alchemist Kraken and a dual mono LM3886 chipamp.

The figures supplied so far are from the Kraken, but the Claymore also has readings within similar range. Are the start-up and power down readings a problem bearing in mind the voltage only peaks for a split second?

Thanks

Richard
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