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Inspire by Dennis Had Enjoying Vacuum Tube Audio

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  #6521  
Old 08-04-2021, 07:46 AM
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straitwire straitwire is offline
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Hey Isaacc7, the power trans 6.3v filament winding can handle much more than that.
The KT88 draws 1.6 and the KT170 draws 1.75 or more.

Last edited by straitwire; 08-04-2021 at 11:14 AM. Reason: incorrect
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  #6522  
Old 08-04-2021, 12:20 PM
Kris0603 Kris0603 is offline
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First, thanks to the admins for access, and thanks to this community for this epic thread! Haven't quite read the whole thing from beginning to end yet, but i've spent many hours coming from Google on various things.

Was lucky enough to snag one of the recent Inspire KT88 SEP amps off eBay and what an incredible upgrade. I had a Elekit 8200R before in my system. Speakers are Dali Evidence 470 (90dB), DAC is an Abbas Audio 4.1SE. Sources are FLAC through a Squeezebox, as well as IPTV, an Airport Express. All toslink into an auto-switcher feeding via coax to the Abbas.

Have been rolling tubes like a madman in this amp, but right now it has the stock Genalex KT88 tubes, and a great Raytheon VT-231 that i had in stock. Tried some GEC KT88 i had, but decided to wait until i've settled on everything else. Been experimenting some with the rectifier tube, and today i finally put in a CV378 i had and it made a big difference. Had tried a Philips GZ34, as well as some 5U4 types. But the CV378 absolutely smokes everything i've tried so far. Better definition in the bass, everything sound exquisitely balanced, i feel the limiting factor now are my Dalis.

Is there any risk to the 5V winding from running this tube? After 30 mins the power tranny is barely warm to the touch. Think i'm going to try some KT150 next but i also have some 5933W i'd like to try with an adapter. Edit: Duh, same heater draw as a 5U4G, 3 amps.

Also have some type 83 MV rectifiers on hand and have been in helpful contact with Mr. Had on fitting a switch on the HT center tap but as good as these CV378 are i have a hard time believing it can truly be bettered. Maybe when i've used out the two CV378 i have.

Last edited by Kris0603; 08-04-2021 at 06:38 PM. Reason: Answered my own question :)
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  #6523  
Old 08-04-2021, 08:03 PM
Isaacc7 Isaacc7 is offline
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Quote:
Originally Posted by straitwire View Post
Hey Isaacc7, the power trans 6.3v filament winding can handle much more than that.
The KT88 draws 1.6 and the KT170 draws 1.75 or more.
Ok, good to know thanks!
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  #6524  
Old 08-05-2021, 12:01 AM
Isaacc7 Isaacc7 is offline
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Quote:
Originally Posted by Kris0603 View Post
First, thanks to the admins for access, and thanks to this community for this epic thread! Haven't quite read the whole thing from beginning to end yet, but i've spent many hours coming from Google on various things.

Was lucky enough to snag one of the recent Inspire KT88 SEP amps off eBay and what an incredible upgrade. I had a Elekit 8200R before in my system. Speakers are Dali Evidence 470 (90dB), DAC is an Abbas Audio 4.1SE. Sources are FLAC through a Squeezebox, as well as IPTV, an Airport Express. All toslink into an auto-switcher feeding via coax to the Abbas.

Have been rolling tubes like a madman in this amp, but right now it has the stock Genalex KT88 tubes, and a great Raytheon VT-231 that i had in stock. Tried some GEC KT88 i had, but decided to wait until i've settled on everything else. Been experimenting some with the rectifier tube, and today i finally put in a CV378 i had and it made a big difference. Had tried a Philips GZ34, as well as some 5U4 types. But the CV378 absolutely smokes everything i've tried so far. Better definition in the bass, everything sound exquisitely balanced, i feel the limiting factor now are my Dalis.

Is there any risk to the 5V winding from running this tube? After 30 mins the power tranny is barely warm to the touch. Think i'm going to try some KT150 next but i also have some 5933W i'd like to try with an adapter. Edit: Duh, same heater draw as a 5U4G, 3 amps.

Also have some type 83 MV rectifiers on hand and have been in helpful contact with Mr. Had on fitting a switch on the HT center tap but as good as these CV378 are i have a hard time believing it can truly be bettered. Maybe when i've used out the two CV378 i have.
Congrats on the new amp! I had an Elekit tu-8300 I think. It was quite good but the Firebottle is on another level. And it is much more fun from a tube rolling perspective.

Speaking of tube rolling. I think I'm at the end of my output tube rolling for now. I'm using an old JAN RCA 5u4g and a tall Sylvania 7n7 with all of these tubes. I really like the sound of the Ken Rad 6v6. Will try some other 6v6 and 7c5 tubes in a while. My favorite output tubes are the Firenti 807, Tungsol 6ar6, and now the Mullard El38. The 807 and 6ar6 are pretty similar sounding which shouldn't be a surprise. They are warm and thick sounding. They are my go to "chocolate cake" presentation choice.

The El38 is amazing, clarity galore, and the cleanest sound I've heard. Last night I called the bass anemic but that was only in contrast to the 6ar6. Turns out the El38 was going as deep but it is much more accurate. I was so impressed with the El38 I went ahead and bought 10 of them which should be a lifetime supply. They seem to be getting scarce so I bit the bullet and bought a bunch.

I think all of these old tubes clearly outclassed the new production tubes I tried, the Psvane kt88 treasure, the Tungsol 7581a, and the Tungsol 6v6.

My new Supratek preamp came today but it's stuck upstairs! I'm partially disabled and rely on my housemates to bring heavy thing to me. I waited 4 months for it and now it's just out of my reach! Gah! Anyway, I will leave the el38 tubes in while I try to dial in the Cabernet preamp.
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  #6525  
Old 08-05-2021, 07:37 AM
Leew Leew is online now
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I currently have the Lp27 and the 45 Set amp.
The 300B is haunting me it's something that I have wanted since hearing one with Klipsch Cornwall's 20+ years ago. What am I losing or gaining by skipping the preamp and using the 300B as an integrated amp (is it designed to be used without a preamp ?).

If nothing else it might appear to my wife that I was downsizing.

Thanks,

Lee
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  #6526  
Old 08-05-2021, 08:06 AM
bearcity bearcity is offline
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Quote:
Originally Posted by Leew View Post
I currently have the Lp27 and the 45 Set amp.
The 300B is haunting me it's something that I have wanted since hearing one with Klipsch Cornwall's 20+ years ago. What am I losing or gaining by skipping the preamp and using the 300B as an integrated amp (is it designed to be used without a preamp ?).

If nothing else it might appear to my wife that I was downsizing.

Thanks,

Lee


Lee,

Dennis is installing a volume control on the 300b so yes it can be used w/o a preamp. In fact, I recall that is how Dennis listens to vinyl in his home/reference setup. As to what you gain or loose? You will gain clarity and loose gain. With sensitive enough speakers you will be fine.
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  #6527  
Old 08-05-2021, 08:28 AM
Leew Leew is online now
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Quote:
Originally Posted by bearcity View Post
Lee,

Dennis is installing a volume control on the 300b so yes it can be used w/o a preamp. In fact, I recall that is how Dennis listens to vinyl in his home/reference setup. As to what you gain or loose? You will gain clarity and loose gain. With sensitive enough speakers you will be fine.
I think my Belle Klipsch are 104db, the volume at 9:00 on the preamp is almost to loud.

My phono preamp has a variable 0-47 gain

Thanks,

Lee
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  #6528  
Old 08-05-2021, 09:47 AM
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Analog Addict Analog Addict is offline
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Quote:
Originally Posted by Kris0603 View Post
First, thanks to the admins for access, and thanks to this community for this epic thread! Haven't quite read the whole thing from beginning to end yet, but i've spent many hours coming from Google on various things.

Was lucky enough to snag one of the recent Inspire KT88 SEP amps off eBay and what an incredible upgrade. I had a Elekit 8200R before in my system. Speakers are Dali Evidence 470 (90dB), DAC is an Abbas Audio 4.1SE. Sources are FLAC through a Squeezebox, as well as IPTV, an Airport Express. All toslink into an auto-switcher feeding via coax to the Abbas.

Have been rolling tubes like a madman in this amp, but right now it has the stock Genalex KT88 tubes, and a great Raytheon VT-231 that i had in stock. Tried some GEC KT88 i had, but decided to wait until i've settled on everything else. Been experimenting some with the rectifier tube, and today i finally put in a CV378 i had and it made a big difference. Had tried a Philips GZ34, as well as some 5U4 types. But the CV378 absolutely smokes everything i've tried so far. Better definition in the bass, everything sound exquisitely balanced, i feel the limiting factor now are my Dalis.

Is there any risk to the 5V winding from running this tube? After 30 mins the power tranny is barely warm to the touch. Think i'm going to try some KT150 next but i also have some 5933W i'd like to try with an adapter. Edit: Duh, same heater draw as a 5U4G, 3 amps.

Also have some type 83 MV rectifiers on hand and have been in helpful contact with Mr. Had on fitting a switch on the HT center tap but as good as these CV378 are i have a hard time believing it can truly be bettered. Maybe when i've used out the two CV378 i have.
Find some old stock US made Tung Sol solid plate 6550s. They don’t have to be new, but should test strong. Your ears will thank you.
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  #6529  
Old 08-05-2021, 12:24 PM
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straitwire straitwire is offline
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Quote:
Originally Posted by Isaacc7 View Post
Hey straitwire, do you know how much current the heater circuit can handle in the firebaottle kt88? I'm looking at some tubes that pull 1.5 amps on the heater.
The 6.3v winding is 6 amps.
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  #6530  
Old 08-05-2021, 05:48 PM
Bombadil Bombadil is offline
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May be too early comparison, but after running in the metal RCA 6F6 / VT-175 for a few days, I took the opportunity to compare them to new production Gold Lion KT66 which have 200-300 hours on them.

This is in an Inspire Parallel Single Ended amp. The 6F6 produce 8 wpc vs the KT66 16 wpc. Volume levels were moderate so I don't think the extra power was a significant factor. Speakers 91db efficiency. Used the same 6SN7 and 5Y3GT rectifier for both.

Used songs very familiar to me, as performed by Rebecca Pidgeon, Nancy Bryan and Holly Cole.

To my ears the KT66 were the clear winners. Big open, natural sound. Vocals sounded much more natural, more like they were in the room with me and well separated from the instruments. Stronger acoustic bass. Midrange & vocals were less forward, sounded "more right." Same for piano.

The 6F6 produced a smaller soundstage, with vocals, strings, and piano pushed more forward in the recording. Deeper bass was okay but not quite as full.

Maybe if I had darker sounding speakers the forwardness I heard from the 6F6 would be more appealing. I listened to a couple of Cat Stevens songs and my impression was that he was shouting at me. Although those songs are not first rate recordings.
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