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-   Inspire by Dennis Had (https://www.audioaficionado.org/forumdisplay.php?f=184)
-   -   Dennis Had Inspire Amps (https://www.audioaficionado.org/showthread.php?t=24170)

cgn-dt-n 07-28-2022 10:25 AM

Quote:

Originally Posted by Isaacc7 (Post 1064329)
A while ago I had asked about modifying my amp so that I could use 12v tubes on the input. Got some helpful responses but in the end I decided against modding the amp. There was just too much chance of really screwing it up. I found someone on Head-Fi that had the answer. It's an external power supply just for tube heaters and a custom adapter.

https://www.isaharr.com/wp-content/u...7/IMG_0480.png

Here's what it looks like in action. Using a 14n7.

https://www.isaharr.com/wp-content/u...7/IMG_0482.png

https://www.isaharr.com/wp-content/u...7/IMG_0483.png

This is a variable supply. I spent a little extra on that instead of a dedicated 12.6v supply in case I wanted to try some 4v tubes in the future. The adjustment knob is really touchy. 12.5 is as close as I've been able to get without overshooting. It's close enough. He originally designed it so that folks could use gu50 tubes. It cost me a little over $100, would be less if I just got the 12.6 version. If I had thought about it I probably could have arranged it so that the wire would be routed towards the back of the amp instead of the front. Oh well.

Now I can use all of my fancy 12sn7 tubes like the coveted Tungsol round plate with black glass and even 12v only versions like the 12sx7 and the 2c50. This lowly 14n7 with angled plates sounds awfully good. Think I'll let that ride for a while.

Hi Isaacc7

in principle, I find the idea of using 12 V tubes interesting and the implementation with the additional device good.
There are certainly many great ways to find your personal sound with the tubes.

For me personally, the variable supplay would be too uncertain. with a mismatch to cause damage to the tubes or amplifier.

Do you have experience with the SRS551, F3a ; RS1003 tube?
One Uf 6.3 Volt / If 2.1 Ampere Pentode

Isaacc7 07-28-2022 11:28 AM

The supply seems to be very stable with restarts. Since I'm only using one voltage right now I'm not worried about damaging any tubes.

I have not heard of those, please tell me more. I'm always interested in learning about new tubes:)

cgn-dt-n 07-28-2022 01:31 PM

Hi,

unfortunately I don't know much about this tube.
It should be able to transmit frequencies up to the megaherz range.

Rike Audio model Romy 20SE uses the tube.

Isaacc7 07-28-2022 11:25 PM

Does anyone know what voltage the input tube is run at? I love my cv1102 but it's max voltage is 250v and is designed to be run at 180 normally. I love the sound but I worry that I'm burning them up.

Edit: Nevermind. I see Dennis said in a much earlier post that the input tube is regulated at 250v. So yeah, guess it's not a great idea to run a tube there if its maximum is 250v.

Isaacc7 08-07-2022 08:03 PM

Looks like some posts were lost in the weirdness with the site the other day. Oh well...

My current tube combo is the Tungsol round plate black glass 12sn7 with KenRad 6f6 output tubes. Very natural and easygoing kind of sound. Very well balanced.

For those of you that have enough space on your amps for and adapter, or if your preamp is compatible, I can highly recommend the Raytheon 6j5gtw tubes. I've been using the 12j5gtw in my preamp. Super open and deep sound. I've switched over to using National Union 12j5gt. They seem a bit more closed in but a little richer sounding. Haven't heard a twin triode with the same kind of sound combo.

Isaacc7 08-10-2022 08:10 PM

Finally listening to the Sylvania 6k6gt. These look like later versions with the small top silvering. Combined with the 14af7 and Tungsol 5w4gt they are making sweet music.

Well, sweet as compared to the Ken Rad 6f6, Tungsol round plate 12sn7, and RCA 5y3gt. That combo was a bit brighter and a little more "hifi" sounding to me. Also, I think I'm giving up on RCA 6f6, they just sound flat and a bit tinny regardless of the driver tube I try.

Analog Addict 08-11-2022 10:41 AM

Another day at the toy shop....
 
A couple of fellows, Dave and Dan stopped by the shop to do some listening, and after we picked their jaws up off the floor, they decided to do some shopping as well. The 2A3 is now gone along with the first production 7C5 amp and the first pair of Inspire speakers to leave the showroom floor.

The master at work....:thumbsup:

https://live.staticflickr.com/65535/...f2a98b59_b.jpgUntitled by analog addict, on Flickr


The line up...

https://live.staticflickr.com/65535/...b133197d_b.jpgUntitled by analog addict, on Flickr



The new prototype phono preamp, my phono pre amp (no cathode follower) and a CJ5 preamp, (chosen for it's high/100Kohm input impedance)

https://live.staticflickr.com/65535/...ebbc010b_b.jpgUntitled by analog addict, on Flickr


The new 7C5 amp. The cost of the rectifier is probably 3-4 times that of all the rest of the tubes...

https://live.staticflickr.com/65535/...4a77aa2e_b.jpgUntitled by analog addict, on Flickr

https://live.staticflickr.com/65535/...86b4d7e8_b.jpgUntitled by analog addict, on Flickr


Getting ready to head off to their new home....

https://live.staticflickr.com/65535/...e75b7a86_b.jpgUntitled by analog addict, on Flickr


Both these gentlemen were essentially unaware of this thread, so I gave them the info. Hopefully they will join up and post their impressions.

The Ziracote veneered pair of Inspire speakers will soon be for sale as well. Look for an ad in the Marketplace. We will be making more of these to order as well, in whatever veneer your heart might desire...

https://live.staticflickr.com/4485/3...1ea23b78_b.jpgUntitled by Analog Addict, on Flickr

https://live.staticflickr.com/4453/2...f3e01b02_b.jpgUntitled by Analog Addict, on Flickr

https://live.staticflickr.com/4463/3...800fa575_b.jpgUntitled by Analog Addict, on Flickr

cgn-dt-n 08-11-2022 01:01 PM

Quote:

Originally Posted by Isaacc7 (Post 1064764)
Finally listening to the Sylvania 6k6gt. These look like later versions with the small top silvering. Combined with the 14af7 and Tungsol 5w4gt they are making sweet music.

Well, sweet as compared to the Ken Rad 6f6, Tungsol round plate 12sn7, and RCA 5y3gt. That combo was a bit brighter and a little more "hifi" sounding to me. Also, I think I'm giving up on RCA 6f6, they just sound flat and a bit tinny regardless of the driver tube I try.


Hi Isaacc7,
I can confirm the good sound of the Raytheon 6j5gtw. they are almost as good as my Fivre and cost significantly less.

try the Phillips 6j5 mil. tube. looks like a 6sn7, but only 1Triod system is active inside.

Very balanced sounded, and absolutely quiet. no rustling and humming.

I have no experience with the 6f6, but I don't like the RCA 5y3gt.
I find these a bit flatter and slightly metallic, try a phillips or slvania instead of this one

cgn-dt-n 08-11-2022 01:11 PM

the speakers in the d ́appolito design look great with the bright veneer.

what specifications will they have?

a 45 or 46 pse amplifier or better still mono blocks in QMB-25 style could still be a temptation for me, but the 300b djh that drives my horns is already pure madness. it would probably just be different but not really better.

eagerly waiting for the phono amp I ordered....

Isaacc7 08-11-2022 07:30 PM

Quote:

Originally Posted by cgn-dt-n (Post 1064802)
Hi Isaacc7,
I can confirm the good sound of the Raytheon 6j5gtw. they are almost as good as my Fivre and cost significantly less.

try the Phillips 6j5 mil. tube. looks like a 6sn7, but only 1Triod system is active inside.

Very balanced sounded, and absolutely quiet. no rustling and humming.

I have no experience with the 6f6, but I don't like the RCA 5y3gt.
I find these a bit flatter and slightly metallic, try a phillips or slvania instead of this one

I am loathe to spend much money on rectifiers. It isn't clear to me how different diodes feeding a capacitor can have all that much impact on the sound especially since the entire idea of the power supply is to provide DC to the circuit. DC, whether brought about via fancy tube rectifiers or solid state diodes, should always be the same. If different rectifiers do change the sound then that would imply that the power supply has some AC, noise, or something else that isn't DC going into the circuit.

If I were going to test that belief, the 5y3 would be a good one to do it with. They aren't all that expensive compared to 5ar4 or 5u4. Maybe the next time I put in a tube order I'll try one.


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