Brines FT-1600 Mk2 Build

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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…

SpeakerInductor.jpg


Thanks

Richard
 
vitalstates said:
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
 
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
 
Tripmaster said:
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
 
vitalstates said:


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
 
Tripmaster said:
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.


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
 
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
 
Bob Brines said:



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.





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

Bob


Hi Bob

Thanks for letting me know.

I’ve changed my mind again regarding finish! I was going to apply Danish oil followed by a clear wax, but after some considerable thought I might apply a satin varnish with a UV additive to help prevent the wood from oxidising. Decision paralysis! ;)

Richard
 
Tripmaster said:



Hi Bob

Thanks for letting me know.

I’ve changed my mind again regarding finish! I was going to apply Danish oil followed by a clear wax, but after some considerable thought I might apply a satin varnish with a UV additive to help prevent the wood from oxidising. Decision paralysis! ;)

Richard

Well, I wouldn't.

I do a lot of things with my demo boxes that I wouldn't do with a customer's cabinets. I put satin acrylic on a pair of FB-20's. The finish is dull and lifeless. It looks like plastic. Don't ever, EVER put satin anything over a good piece of wood.

Wood is photo reactive. All wood will darken with time, some more that others. Cherry and maple are good examples of woods that take on a patina rather different from the raw wood. Natural cherry, BTW is my favorite finish. It takes a couple of years for the wood to take on its final color.

You will have put a lot of time into your speakers. Take time to do a decent finish. I've used three different oil finishes: Minwax Tung Oil Finish, Watco Danish Oil and Fornby's Tung Oil Finish. Of the three, Fornby's is easiest to apply, as it does not need to be rubs off while wet. Just wipe on four thin coats with a light rubbing with 0000 steel wool. Of the other two, the Minwax is hardest to rub off, but builds faster and I like the finish better than Watco. A lot of personal preference here. I am currently using the Fornby's for production.

Hint: The best applicator for wipe-on finishes is Bounty brand paper towel. I've tried everything I can think of and tried all of the recommendations and the Bounty towel are the most lint free.

Bob
 
Bob Brines said:


Well, I wouldn't.

I do a lot of things with my demo boxes that I wouldn't do with a customer's cabinets. I put satin acrylic on a pair of FB-20's. The finish is dull and lifeless. It looks like plastic. Don't ever, EVER put satin anything over a good piece of wood.

Wood is photo reactive. All wood will darken with time, some more that others. Cherry and maple are good examples of woods that take on a patina rather different from the raw wood. Natural cherry, BTW is my favorite finish. It takes a couple of years for the wood to take on its final color.

You will have put a lot of time into your speakers. Take time to do a decent finish. I've used three different oil finishes: Minwax Tung Oil Finish, Watco Danish Oil and Fornby's Tung Oil Finish. Of the three, Fornby's is easiest to apply, as it does not need to be rubs off while wet. Just wipe on four thin coats with a light rubbing with 0000 steel wool. Of the other two, the Minwax is hardest to rub off, but builds faster and I like the finish better than Watco. A lot of personal preference here. I am currently using the Fornby's for production.

Hint: The best applicator for wipe-on finishes is Bounty brand paper towel. I've tried everything I can think of and tried all of the recommendations and the Bounty towel are the most lint free.

Bob

OK, thanks for the tips!

Back to plan A…I just popped into my local hardware store and picked up a tin of Liberon Danish Oil (now with an added UV filter!) I’ve used their finishing oil before and loved the results.

I took your advice and purchased a pack Bounty kitchen towels (Recently renamed to ‘Plenty’ in the UK)

Don’t worry…I plan to take my time with the finish. It’s taken a while to get to this stage with work and family commitments. My wife will soon have a husband again!

Richard
 
I don't suppose you blokes have Cabots branded Danish Oil over there? It's polyurethane based, takes on a lovely luster, brings out the grain as oil should and is longer lasting due to the poly.

Very easy to apply with 0000 steel wool and actually rubs off very well, even when its gumming up. If the timber is finished well then 2 coats is enough for a lovely finish. Of course more is better, but it becomes marginal.

If you have some gloss lacquer (or semi-gloss) laying around and some off cut timber, paint a few strokes on one half of the wood without stirring the pot. Then stir the pot and paint a few strokes beside the first strokes.

Once cured this should show the difference between gloss and satin as the compounds that create the shine settle at the bottom of the paint tin and must be stirred in. The same applies to spray-cans.
 
lazyfly said:
I don't suppose you blokes have Cabots branded Danish Oil over there? It's polyurethane based, takes on a lovely luster, brings out the grain as oil should and is longer lasting due to the poly.

Very easy to apply with 0000 steel wool and actually rubs off very well, even when its gumming up. If the timber is finished well then 2 coats is enough for a lovely finish. Of course more is better, but it becomes marginal.

If you have some gloss lacquer (or semi-gloss) laying around and some off cut timber, paint a few strokes on one half of the wood without stirring the pot. Then stir the pot and paint a few strokes beside the first strokes.

Once cured this should show the difference between gloss and satin as the compounds that create the shine settle at the bottom of the paint tin and must be stirred in. The same applies to spray-cans.

Hi

It sounds a little bit like Patina. I used this on a dining room table I made a few years ago. It has a gel like consistency, is really easy to apply and produces a semi gloss finish. I decided against using this product because it develops a slightly orange colour. Its a good product.

Richard
 

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Out of interest I measured the offset on my LM3886 Chipamp and the readings are much lower than my other two amps.

Right Channel

- Power on peaks for a split second at 0.2mV
- Idles at 0.2mV
- Power off peaks for a split second at 4.6mV

Left Channel

- Power on peaks for a split second at 5.5mV
- Idles at 0.4mV
- Power off peaks for a split second at 4.6mV
 
If the Patina product is as its name suggests then its target it to attain a patina finish, that is, antique. A deep luster only years of aging and polishing over that time will bring. Premature aging if you will.

Cabots Danish oil is just an oil product with a hardening compound added to give a more durable finish to the timber. It's wet whereas you say patina is gel-like, which also gives the impression its aim is a 'patina' finish.

Those offset measurements are very very low. Good stuff!
 
Tripmaster said:
Out of interest I measured the offset on my LM3886 Chipamp and the readings are much lower than my other two amps.

Right Channel

- Power on peaks for a split second at 0.2mV
- Idles at 0.2mV
- Power off peaks for a split second at 4.6mV

Left Channel

- Power on peaks for a split second at 5.5mV
- Idles at 0.4mV
- Power off peaks for a split second at 4.6mV


what about the cones?, do the cones move with the chipamp at startup?
 
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