AudioAficionado.org - Dennis Had Inspire Amps

AudioAficionado.org (https://www.audioaficionado.org/index.php)

- Inspire by Dennis Had (https://www.audioaficionado.org/forumdisplay.php?f=184)

- - Dennis Had Inspire Amps (https://www.audioaficionado.org/showthread.php?t=24170)

Quote:

Originally Posted by straitwire (Post 963272)

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.

[IMG]https://i.imgur.com/rZYhDd6.jpg[/IMG]

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.

[IMG]https://i.imgur.com/cd3ZYi9.jpg[/IMG]

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).

[IMG]https://i.imgur.com/xmDJUiC.jpg[/IMG]
[IMG]https://i.imgur.com/k3mdhNu.jpg[/IMG]

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.

[IMG]https://i.imgur.com/C67PRCA.jpg[/IMG]
[IMG]https://i.imgur.com/vLPwOgn.jpg[/IMG]

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.

[IMG]https://i.imgur.com/6FegHXc.jpg[/IMG]
[IMG]https://i.imgur.com/UMnP1sJ.jpg[/IMG]

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

[IMG]https://i.imgur.com/xfUMx55.jpg[/IMG]
[IMG]https://i.imgur.com/0owOdUK.jpg[/IMG]
[IMG]https://i.imgur.com/pl0JO8F.jpg[/IMG]

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

[IMG]https://i.imgur.com/29pUMM8.jpg[/IMG]

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

[IMG]https://i.imgur.com/LVXniZg.jpg[/IMG]

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

[IMG]https://i.imgur.com/5QKmXW8.jpg[/IMG]

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.

[IMG]https://i.imgur.com/RCrVBHx.jpg[/IMG]
[IMG]https://i.imgur.com/cI8dYBE.jpg[/IMG]

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

[IMG]https://i.imgur.com/cA6VhKA.jpg[/IMG]
[IMG]https://i.imgur.com/N3uX8vX.jpg[/IMG]

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.

[IMG]https://i.imgur.com/ogqrQV1.jpg[/IMG]

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.

[IMG]https://i.imgur.com/I1iLKDw.jpg[/IMG]
[IMG]https://i.imgur.com/0MwwBwH.jpg[/IMG]

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

Well, the pre amp is done, and when I left town, Dennis had it over at his house in his main system (I think he likes it!) Here's what the finished product looks like...

https://live.staticflickr.com/65535/...a660f114_z.jpg Untitled by Allan Shang, on Flickr

https://live.staticflickr.com/65535/...bf07b2b2_z.jpg Untitled by Allan Shang, on Flickr

https://live.staticflickr.com/65535/...45dcabb0_z.jpg Untitled by Allan Shang, on Flickr

Here is the underneath view featuring dual 5 VDC filament supplies, Solid silver wiring in the signal path, including one set of silver input leads with hand wrapped coaxial wire, vintage medical grade Vitamin Q caps on the outputs, and of course Tony's ground breaking volume remote control.

https://live.staticflickr.com/65535/...40de7e66_z.jpg Untitled by Allan Shang, on Flickr

My first two impressions were the creaminess of the sound and the gigantic sound stage. Dennis may have tinkered with it even further, since I've been out of town the last week and he was kind enough to donate the electrons to help break it in. Realize some of those 01As are almost 100 years old...:eek2:

Here's the roll off effect of not using a cathode follower with longer cable length. One trace is 3', the other is 20'. Pretty easy to guess which is which.

https://live.staticflickr.com/65535/...5c22af7f_z.jpg Untitled by Allan Shang, on Flickr

And here is the remote control. I'll need to do some testing to determine the range, but hopefully it's at least couch distance. Click on the pic for video.
Now I just have to figure out how to reattach the bottom plate since Tony put the remote circuitry right underneath the screw holes... :D

https://live.staticflickr.com/31337/...7e19459d_z.jpg Untitled by Allan Shang, on Flickr

It's possible that you all might see a new Inspire "LP-01A" pre amp at some point in the future, but what do I know?...:smoking:

[QUOTE=Miami Ed;973811]

Quote:

Originally Posted by decooney (Post 973792)

Decooney, I ran a few preamps running the gamut from a couple of cheap Chinese preamps to my Aikido 12vdc with an Alps Blue Velvet volume control. Of these, the Aikido sounded the best.

The 3.1 is a marked improvement, in transparency and soundstage.

Ed

Hello Ed. That's great! Bet it sounds nice. I looked at the Aikido DIY units a little, circuit boards and all, hmm..., P2P for sure here on out. A friend and member here hinted at me trying his Inspire LP27 for grins, but I won't give up my remote control with my Cary SLP-98 "sweet little preamp" with huge outboard transformer; sounds great, formerly designed by Mr. Had too. I visited a buddy who compared several high $ other brand preamps to his upgraded SLP98 to units 2x to 4x the cost, both of us preferred our upgraded 98s. Perhaps it was a synergy there too. Will keep an eye out on developments here with all the Inspiring development work going on, good fun and continued progress for sure :thumbsup:

Another fine preamp is the AES AE3 MKII. It's an anode follower with a pair of 6SN7's and a 5AR4 rectifier and remote. It's totally quiet and has a full liquid sound very well suited to Jazz. Not sure the difference between anode and cathode follower but it works well with my 6f6 Inspire.

[QUOTE=decooney;973914]

Quote:

Originally Posted by Miami Ed (Post 973811)

Decooney, I agree with you that point to point wiring is best practice. The Aikido boards are very high quality though.

I remember looking at your preamp years ago. I would be interested to hear the difference between the Cary and the most recent designs out of Dennis’ fertile imagination.

I bet your setup sounds great with the 6f6 tubes. I like these tubes but I just don’t have speakers that mate well with them.

[QUOTE=Miami Ed;974032]

Quote:

Originally Posted by decooney (Post 973914)

...

I bet your setup sounds great with the 6f6 tubes. I like these tubes but I just don’t have speakers that mate well with them.

While I use the SLP on the front-end, I actually use a different set of mono amps with massive transformers and larger output tubes on the back-end for that same reason. My particular custom build speakers require more than a wee bit more power/drive for the added dynamics and larger-room filling sound I'm looking for. Tube rolling with a few more NOS Mullard input tubes soon and getting closer. I still enjoy reading and learning about the Inspired progress here too though :)

Not sure what color I would choose if I were having an amp or preamp built. My two Inspire amps are gloss black and ivory. Both of those are okay but wouldn't be my first choice.

I'm assuming there are a wide range of choices. Is there a finite list of choices or almost anything that one can buy down there?

I might go with a metallic blue. Either medium or dark. I've also always liked metallic dark orange, but not sure I'd go in that direction. There is a bicycle company near me which has a custom color where they first paint the bike in metallic silver and then an orange layer over it. Beautiful.

The dark metallic grays common in new cars are a nice color too.

My current gear is a mish-mash of colors. Black, white, silver, gold, ivory. I've never made a purchase based upon color matching.

General question for those with fire bottle amps and relatively high output sources; am I missing anything by running my dac straight into an inspire 45?

Dennis built my amp (like some others) with a volume pot on the front. My dac also has a remote control that can adjust volume. I can play way louder than I ever would want but not sure if I'm missing out on something a preamp would give. Obviously I could buy and try but would like to get a few opinions first so I don't end up with something I don't need. I know one person here who skips the pre stage and goes straight to the amp from his turn table.

Speakers are a set of Omega Junior 8s at 98db.

From my limited experience with headphones I know loudness is not a good measure of performance, but not entirely sure this situation is applicable since the speakers are already getting amplification/power.

Appreciate any input the collective has for this newby.

Quote:

Originally Posted by pechelman (Post 974365)

I use a Cary 303T SACD player into a 6SN7 preamp into 6f6 Inspire. The 303T has a switchable tube or solid state output. With the tubes switched in it sounds a lot better. More musical and full, big difference in the sound of voices and horns. The 303T feeds into a 6SN7 preamp. This allows you to tune the sound to your liking by rolling tubes. The 6SN7 tubes come in many flavors from fast and detailed to mellow and full. Makes listening fun when you can try various tube combinations. Bet you would enjoy adding a preamp.

Quote:

Originally Posted by pechelman (Post 974365)

Appreciate any input the collective has for this newby.

pechelman,
Similar to Maro, the results were similar w/wo adding a tube or solid state preamp. Often a tad bright or not as smooth as I would have preferred when not having a good preamp (with the added ability to fine tune tone) before the amp.

In addition, just for grins several times I've also connected direct from various volume-controlled sources direct into my former Cary & Inspire tube amps as a test. In each of those cases the listening sessions did not last too long losing interest. Yes it was nice, clean, but not as smooth, often times a tad dry and not as musical in my particular systems.

Today for digital sources, now running a tube ladder DAC with a vintage NOS tube, into a tubed preamp with NOS tubes, into tube amplifiers with NOS input/driver tubes linked with specific types/lengths of RCA interconnect cables to achieve (passive EQ) to a particular tone that serves the speakers and ears well. The end results is so much nicer than without a nice preamp. :chillin:

Quote:

Originally Posted by pechelman (Post 974365)

Appreciate any input the collective has for this newby.

pechelman,
Similar to Maro, the results were similar w/wo adding a tube or solid state preamp. Often a tad bright or not as smooth as I would have preferred when not having a good preamp (with the added ability to fine tune tone) before the amp.

In addition, just for grins several times I've connected direct from various volume-controlled sources direct into my former Cary & Inspire tube amps as a test. In each of those cases the listening sessions did not last too long losing interest. Yes it was nice, clean, but not as smooth, often times a tad dry and not as musical in my particular systems.

Today for digital sources, now running a tube ladder DAC with a vintage NOS tube, into a tubed preamp with NOS tubes, into tube amplifiers with NOS input/driver tubes linked with specific types/lengths of RCA interconnect cables to achieve (passive EQ) to a particular tone and sound stage that serves the speakers and ears well. The end results is so much nicer than without a nice preamp. :chillin: