Dennis Had Inspire Amps

[BearCityUSA]

Dennis has had my 2013 KT amp to do some mods. New OPTs, Coupling Caps, added a bias circuit (in 2013 he was not biasing each channel separately). Cannot wait to get it back but it seems he has taken it home and his wife likes it so much she wants him to build another one just like it before letting it go. Makes me think I have something extra special in store.

[straitwire]

Well I finally got back to work on Analog's preamp, I painted the electrolytics and installed the RF remote volume control unit and its power supply.

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I took a bunch of pictures of this remote control build.
This is not an Inspire product, but it is a fun project that is cheap and not too hard to build with a few basic tools.
The remote unit itself I buy from eBay for less than $10, so I buy a few of them.
The AC adapter is 12V at 1A they cost around $2 on eBay.
The vol pot is a motorized Alps Blue Velvet 100KAX2 they cost $35-$45 on eBay.
The people who make our front panels make the overlay for the key fob remote.

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This is the remote control unit removed from the black box.
You have to do a few things to it to make it control a motorized volume pot.
First you remove the bus bar if you want to make solder connections, but you can build it without removing the bus bar if you want.
You can also remove the antenna wire and replace it with a longer wire if you need to, (I do).

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On the side of the board near the antenna connection there is a solder bridge, take the soldering iron and melt it apart.
This programs the unit to jog.

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On the back of the board where the relays are there are two solder bridges you need to make.
The relays are single pole double throw, but are being used as single pole single throw.
When you bridge these lands you connect the normally closed poles to ground making the relays single pole double throw enabled.

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Power for the motorized vol pot comes from the 12V supply thru a 33 ohm resistor.

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Connect your 12V power supply wires=Red/Black.
Connect the vol pot control wires=Orange/Black.
Connect the antenna wire=Gray.

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Now the power supply, open the wall wart with a small straight screwdriver.

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Remove the wires from the power supply and keep the plug wire for later to use as an antenna.

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Snip this plastic standoff out of the black box and use it to house the power supply.
This is one of the reasons why I buy more than one remote unit, so I have a box for the power supply.
Go ahead and connect AC wires too.

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The plug wire antenna is plugged into a plastic body 2.5 mm DC jack mounted on the back panel.

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There are several ways to mount the black boxes to the chassis, for this build I am using gel super glue on the bottom plate of the black boxes, this way I am not drilling holes in the chassis and the covers can be removed if necessary without having to remove screws to open the boxes.

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I tack soldered the AC leads for a test, and it works great.
You have to connect it to the vol pot correctly so it will turn in the direction you want it to.
The cap on the motor is a bipolar .01 mfd, it's for noise.

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Well I hope that made sense, if you have any questions feel free to ask...straitwire

[oldtech0]

Originally Posted by bwilson51

Does anyone know how high the tubes are bias on Inspire Sep amps,I was wondering how much stress is put on the output tubes

Hi,

That depends on the Line voltage, Power Transformer, the B+, the rectifier tube and output tubes (Rp) being utilized.
My 5/2016 HO Firebottle uses 360 ohm cathode bias resistors. My 3/19 PSE monobocks have 750 cathode bias resistors.
There are so many flavors of these amps that the only way to know is flip it over and stick a voltmeter on the cathode resistor.
For instance the HO with 122.7 line voltage.
OUTPUT RECTIFIER B+ BIAS

EL34 5U3C 351 47 ma

6F6 5Y3 319 33.05 ma

I have sheets of similar data for various alignments for both type amps.
BTW the HO has regulated screen voltage while the monos do not (YET)

Sorry for the column alignment this text editor has issues

[straitwire]

This one is shipping to the customer today.
The color is called Red Illusions clear coat...so Dennis decided to call it Delusional Red...


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[FloridaBoy]

Originally Posted by BearCityUSA

I’m running 6L6 metal in mine. Outstanding.

I'm running a pair of EL84's with a pair of 6L6GA's and 5Y3G rectifier. Nice.

[BearCityUSA]

Originally Posted by FloridaBoy

I'm running a pair of EL84's with a pair of 6L6GA's and 5Y3G rectifier. Nice.

This is in your PSE? When I got mine I tried for a while mixing power tubes but without much luck. I seemed to gravitate back to quads. As I recall, trying to add clarity with low powered tubes to the punch of higher powered tubes yield less punch but no discernible increase in clarity. Now el84 with 6l6ga’s. Theres an interesting combo. Lower power for both. May try some combos like that. 6v6 -6f6 maybe. I have lots of pairs.

Is yours tube rectified? You mention the 5y3. Mine is SS. Rect is for IIPS and I have not hear a difference as long as the tube is direct heated. Running a Tubestore 274b now because I like the big st shape.

[Comzee]

Originally Posted by BearCityUSA

Rect is for IIPS and I have not hear a difference as long as the tube is direct heated. Running a Tubestore 274b now because I like the big st shape.

Tubestore 274b is actually a rly nice new production rectifier, and I generally dislike almost all the new production rectifiers I've tried.
Even with my KT88 firebottle with IIPS I notice changes with rectifiers tho. I think somebody said earlier in this thread that the tube rectifier is still what supplies the B+.

I've used type 80 rectifiers with IIPS, and they don't give enough power, really kills dynamics, but apart from that they have insane clarity. Probably why Dennis uses type 80 rectifiers in his 45 amps as 45 tubes don't need nearly as much power as pentodes. Err, power, more like voltage drop. Idk something like that.

I bought some 6f6 glass (I know many people were raving about the metal ones here). Even tho they work with my kt88 firebottle, not enough power for my speakers. Going to be using them in the pentode 6v6 headamp I have coming. Excited to see how they compare to kt66/6v6/6l6.

I generally have the same problem with 5y3 as type 80 tho (5y3 is actually electrically very similar to type 80, it evolved from that), low dynamics. I prefer gz34/5r4, maybe a 5u4 if the mood is right. Then again I mostly use kt88 in mine because my speakers need that power. 5y3 probably mesh better with the lower power pentodes such as the 6f6.

[Bombadil]

Originally Posted by Comzee

Tubestore 274b is actually a rly nice new production rectifier, and I generally dislike almost all the new production rectifiers I've tried.
wer. 5y3 probably mesh better with the lower power pentodes such as the 6f6.

Mine came with the Tubestore Preferred Series 274B. It has worked like a champ. Very pleased with it. I've run many other rectifiers in it too and have liked several of them. I generally use a new production Genalex Gold Lion GZ34 but I have no qualms with swapping the Tubestore in at any time.

[FloridaBoy]

Originally Posted by Comzee

Tubestore 274b is actually a rly nice new production rectifier, and I generally dislike almost all the new production rectifiers I've tried.
Even with my KT88 firebottle with IIPS I notice changes with rectifiers tho. I think somebody said earlier in this thread that the tube rectifier is still what supplies the B+.[/B]

I've used type 80 rectifiers with IIPS, and they don't give enough power, really kills dynamics, but apart from that they have insane clarity. Probably why Dennis uses type 80 rectifiers in his 45 amps as 45 tubes don't need nearly as much power as pentodes. Err, power, more like voltage drop. Idk something like that.

I bought some 6f6 glass (I know many people were raving about the metal ones here). Even tho they work with my kt88 firebottle, not enough power for my speakers. Going to be using them in the pentode 6v6 headamp I have coming. Excited to see how they compare to kt66/6v6/6l6.

I generally have the same problem with 5y3 as type 80 tho (5y3 is actually electrically very similar to type 80, it evolved from that), low dynamics. I prefer gz34/5r4, maybe a 5u4 if the mood is right. Then again I mostly use kt88 in mine because my speakers need that power. 5y3 probably mesh better with the lower power pentodes such as the 6f6.

Changing rectifiers appears to change the B+ voltage so the sound changes. I'll try a 5R5GY with the EL84's. I don't seem to have a dynamics issue with the 5Y3G and EL84's but my speakers are 99db and dip to 4.2 ohms.

[nhparrot]

What are folks using as a rectifier with the 6F6 metal tubes? What does Dennis recommend?

Thanks
Glenn