@ezliz
das habe ich hier gefunden
[IMG]https://live.staticflickr.com/65535/...094f837c_o.jpg2 by cgn- dt-n, auf Flickr[/IMG]

Thanks for the welcome happy to be here. Quite new to hobby so please forgive my ignorance.

I saw that image saying it will fit without a adapter so will I will order some K150 or KT120 and give those a try looking for a more neutral and detailed presentation. My current tubes sound warm velvety but lack instrument separation and a tad rolled off. I am comparing it to my Luxman SS amp.

Can a 274B rectifier be used in an Inspire 300B-v?

There are some threads on DIYaudio and Audio Karma discussing the KT120 in particular. The consensus seems to be that recent production needs to be run at a much lower rates than expected to avoid red plating, at least in single ended.

Edit to add: Thinking about it, I doubt that the KT120 would be run at anywhere near their limit on your amp so you'll probably be ok.

This is an absolute beauty. Any idea when it will be available for purchase? Would it be available with a volume control knob like the one in the Fire-Bottle 300B SET? How much will it be?

@Analog Addict

send you pm

Hey all,

Been lurking as a non-member for a while and learning a lot from reading this forum.

Currently running Ayre and Vandersteens. I have never owned a tube amp, but would like to get into it. (I have friends who run 300B amplification.) Any guidance on where to start with a tube amp? I like the idea of learning the ropes with a simple amp and being able to tube roll. I messaged with Dennis when he had a KT88 amp up on ebay a week ago, but I missed out on purchasing. Dennis said it would be a good match for a pair of Vandersteen VLR-CT bookshelf speakers that I have in storage. (Eventually I'd switch to more efficient speakers, Devore, possibly.)

Any thoughts/suggestions on if the KT88 Fire-Bottle would be a good first tube amp? I would likely opt to get it with a volume control knob. (Would a 300B Fire-Bottle be a better way to go?)

Any insights would be appreciated. Thanks in advance.

The KT88 Firebottle is a great amp, especially if your speakers aren’t super efficient. If you want to roll tubes there are few better amps for it. I have an entire thread on this forum dedicated to that topic.

A 300b amp really is a different beast. Unless you have a lot of money 300b rolling is prohibitively expensive. No, 300b amps are designed to listen to, not fiddle with. Dennis’s 300b amps are amazing. The stuff he did with Cary over the years was amazing and by all accounts his new stuff is even better. Triode amps, whether 300b, 2a3, or even super low power 45 based amps have their own vibe and approach. You’re more likely to roll capacitors than output tubes in those kinds of amps.

I think the KT88 Firebottle is a tube hobbyist amp. You can get a lot of different sounds out of it depending on what tubes you use. Purists shudder over that kind of listening but I think it is a lot of fun and very rewarding.

If you want an amp you build a system around and not mess with it then get one of Dennis’s 300b amps. If you want to fiddle and listen to different tubes and/or just don’t want to spend the money on the 300b then by all means get the kt88 Firebottle, it’s a hell of an amp!

Thank you for all this great info. Your post (and a number of others) have me thinking that the 300b Firebottle might be the way to go.

"Triode amps, whether 300b, 2a3, or even super low power 45 based amps have their own vibe and approach."

Can you expand on this a little more?

I've heard the Feliks Audio Arioso 300b Integrated, and compared with a Primaluna (running EL34s) in the same system. Love the 300b amp.

Anything I should know beforehand about running a 300b Firebottle?

Any drawbacks to the KT88 amp?

Thanks again.

ursus… Welcome to AA! :wave:

Thanks! Happy to be here.

(Can you tell me how to PM? Do I need to hit a certain number of posts before I can PM, visit profiles, etc.?)

You will need to become a Subscriber to have full benefits. Here is the link for your convenience;

https://www.audioaficionado.org/payments.php

I think the only disadvantage to the KT88 amp is if you’re looking for a 300b sound it doesn’t have it:) On the other hand, 300b amps can sound very different from one another. If you compare an old Western Electric 300b amp with a new design with something like a newer pentode driver or mosfet follower along with a modern high quality output transformer you will hear very different things. Old triode amps are old and tend to have more of a classic “tubey” sound. Warmish, flabby bass, possibly euphonic. Modern designs tend to lean into the inherent linearity and sound much more “accurate” but in the way only tube amps can be.

Anyway, like I said before, I think 300b amps in general, and Dennis’s in particular are really designed to be used as-is. The KT88 Firebottle is aimed squarely at people that like to fiddle with their stuff. I have… a lot of tubes now because of that amp lol. I think its flexibility allows you to tune it to find the best combo with your speakers.

When I mentioned that triode amps have a different approach I mostly meant that folks that like them tend to get the amp with the tube they like first and then figure out the best speakers for the amp. You’ll end up rolling speakers instead of tubes lol.

[QUOTE=ezliz;1080883]That makes sense I see Dennis is selling his preamps on ebay might have to pick one one up. Hoping to maybe see one on USAM but haven't yet so might have to buy new.

Question I want to try KT150 or KT170 but don't know if they will even fit...currently running quad of KT88 GV Golden Voice output tubes, a Shuguang Treasure CV181-Z, and an RCA 5U4G rectifier.

https://img.usaudiomart.com/uploads/...dennis-had.jpg[/QU

The KT150's envelope is 59mm in diameter.
I laid out this chassis with enough room to accommodate the KT150.
The KT170 was not around when I made the template.
The KT170's envelope is 68mm, so it will not fit.

[QUOTE=ezliz;1080883]That makes sense I see Dennis is selling his premaps on ebay might have to pick one one up. Hoping to maybe see one on USAM but haven't yet so might have to buy new.

You may want to check with Dennis, sometimes he has preamps or amps that have been traded in and he resells those.

I'm not sure if there is room for a volume pot.

[IMG]https://i.imgur.com/QT2cp7e.jpg[/IMG]

Dennis is working on the matching prototype preamp now.
Once he is done with that, we will have a better idea as to when we will be offering them.

Ha! "Rolling speakers," that is funny. (And expensive!) Thanks for the very coherent answers and info. Very helpful. BTW, your "tube rolling" thread is fantastic.

You are looking at Apples vs Oranges in some respects inside the tube world.

Part of this is the SEP vs SET debate, where Triodes would be typically described as more warm and lush while Pentodes would be described as more precise with perhaps some greater presence on the bottom end.

The 300b amp (non PSE) would be good for about 7-8 wpc while the KT-88 amp would be a little north of 10wpc, at least with KT-88s/6550s. The KT-88 amp is typically described as the "universal" amp, with it's ability to play all sorts of different output tubes by changing the rectifier. The 300b is one output tube only but some would argue that with WE 300bs, who needs any other tube?

Of course it's your choice, but the KT-88 amp offers a lot more in the way of experimenting via tube rolling, although it's not hard to change the final stage coupling caps as well. The 300b is dialled in and optimized.

You can't go wrong with either. If you do develop the urge to pull the trigger, PM me and I'll get you set up with Dennis...:thumbsup:

Wonderful. Thanks very much. And, this is a helpful breakdown describing the two different types of amps. I really appreciate the warm welcome and all the great information you guys share on this forum. Very cool.

The Inspire 45 seems to be offered not that frequently. Right now I have an ANK 300B am, however, I‘m still interested in a 45 tube amp since some say their sound is special.

Anyone who has had a chance to listen to music with the Inspire 45?
And: My speakers are the Unison Max 2 speakers (96db). Are they enough for a 45 amp?

Take a look at this page.
This explains in detail performance, volume and efficiency of the loudspeaker.

https://www.jacmusic.com/techcorner/...in-a-watt.html

Thank you. So according to this website, it could my speakers could be efficient enough. Now, the 45 inspire seems to be very rare. Anyone who could compare it to a 300B amp for example? What to expect?

Awesome...thanks Straitwire for your feedback. I'll be watching to see the final EL84/preamp design that Dennis will present. I'm sure it will be a master reference combo.

Fantastic comparisons and explanations. Thank you. When my trigger finger gets itchy I'll shoot you a PM.

I emailed Dennis on ebay no response. However this new preamp you posted interest me for my Inspire power amp. Any details you can share?

Introducing the RB-84...
 

Did something a little different yesterday and went over to Dennis house to listen to the new RB amp and preamp, and also the Inpsire 3.1 speakers. Dennis has continued to fiddle with the 3.1s, until he recently told me he had found the magic sauce, which necessitated me coming by the house to hear them.

The RB-84 pre amp and amp are the new entry level pieces in the Inspire family...

https://live.staticflickr.com/65535/...e099624c_b.jpgUntitled by analog addict, on Flickr

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The RB preamp uses anything from the 6DJ8 family of tubes, such as the 6DJ8, 6922, 7308, 6N1P, 6H1P, 6N2H, 6H30, and also can use a 6CG7 along with a 5Y3 rectifier. There are two input channels, giving the selector switch a "null" position, and of course the volume pot.


And then there's the new RB-84 amp...

https://live.staticflickr.com/65535/...e1b4bbb9_b.jpgUntitled by analog addict, on Flickr

https://live.staticflickr.com/65535/...88e230c9_b.jpgUntitled by analog addict, on Flickr


The RB-84 amp also uses a 6DJ8/6CG7 input along with a pair of 6BQ5s. The rectifier is flexible, with a 5Y3 producing 3 wpc, while a 5U4 produces 5 wpc and a 5AR4 produces 5,5 wpc. Dennis really likes the 5Y3 and my guess is that will be the rectifier it ships with. And no, there's really not enough room to add a volume pot to the Amp.

The pre amp and amp are $2000 each, not including shipping, and will be available in about 6 weeks. PM me for pre orders.


Lastly, the Inspire 3.1 speakers...I don't know where to start. :eek2:

How about the fact that they blew the Tannoys away? That they made Dennis' living room sound like a concert hall. How about that Dennis thinks that they are the best speakers he's ever designed and that he now considers them "World Class"!?! He's now decided to build outboard crossovers for them to prevent altering the inside geometry in any way.

I don't know how we're going to proceed with them because Dennis has soured on the whole outsourcing the manufacturing process, but I am determined to find a way to make these happen. I've never heard such a small pair of boxes produce such an amazing amount of sublime sound. They have to be heard to be believed.

https://live.staticflickr.com/65535/...5603b452_b.jpgUntitled by analog addict, on Flickr

Lastly, for chuckles and grins I brought the Slammer over and we hooked it up in the system...

https://live.staticflickr.com/65535/...d94f79b3_b.jpgUntitled by analog addict, on Flickr

Dennis says it's the best amp I've built so far. I'm inclined to believe him.
I did also drop the welded and sanded chassis off for the 8417 PSE build, of which I have high hopes for. I'm hoping it will be even better than the Slammer.

I'll leave a tease of the 3.1s on the Slammer.(click on the last pic for video/sound) Dennis is listening to it even as I type. Obviously the phone mic is subpar, but perhaps the sense of the air in the music is evident. It truly did sound like we were in a concert hall...:music::music::music::thumbsup:

https://live.staticflickr.com/65535/...c497a21b_b.jpgUntitled by analog addict, on Flickr

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Nice news/photos
The small amplifiers are definitely combined with a single driver or a small horn
an entry level system at a very high level.
I would be curious about the new speakers and would like to hear them, but at the moment there are other priorities.

Great pictures! Is it a point-to-point wiring, auto bias design (RB-84 amp/preamp)? It would be interesting to see what the amp and preamp look like inside.

Inspire RB series...
 

As requested.

Preamp...

https://live.staticflickr.com/65535/...4d9e79e2_b.jpgUntitled by analog addict, on Flickr

Amp...

https://live.staticflickr.com/65535/...f780f5b8_b.jpgUntitled by analog addict, on Flickr

And the "inspiration" born of Dennis listening to a Magnavox console, and drinking Dad's root beer....

https://live.staticflickr.com/65535/...27a1b7f3_b.jpgUntitled by analog addict, on Flickr

https://live.staticflickr.com/65535/...727dc268_b.jpgUntitled by analog addict, on Flickr

Production will begin in a couple of weeks. Get 'em while they're hot!

Revisiting a tube I haven’t used in a very long time for the input on my KT88 Firebottle, the BL63. It is a great tube if you want what I always associate with the the MOV/Marconi/GEC/Osram sound. Rich, warm, and creamy. I’ve got it paired up with some 5b/254m output tubes. They are a smaller, loctal based version of the 807 made by STC, also a great British tube!

The bl63/vr102/cv1102 has gotten kind of expensive but it is still the least expensive way to get that GEC sound with these amps. The GEC b65 is their 6sn7 version and the prices on them will make you weep. The bl63 has a higher heater draw than most. The KT88 Firebottle can handle it no problem but you might want to check if you want to use it in other amps. You’ll need an adapter. It uses the same one as the 6f8g/gc8g.

Speaking of the 807, I wonder what kind of power can be gotten out of them in SE pentode? what about a pair in parallel SE? The anode in pentode mode can take a lot of voltage thanks to the top cap. Would it give up the amazing (IMO) sound it gets in the Firebottle if it got cranked up? If Dennis ever made an amp like that I’d be sorely tempted. Being who I am I would probably request it with regular octal sockets so that I could adapt them to 807, 5b/254m, and 6gb6.

Huh, looks like Gordon Rankin already tried a higher power 807 SE amp with mixed results. https://www.fidelity-online.de/wp-co...ractices-2.pdf

The resulting power isn’t all that much more than what we can get with the KT88 Firebottle. I am also curious if the 20lb output transformers are really necessary. The extra handful of watts requires that much of a jump? I know both Gordon and Mike were both experienced designers but I dunno, seems like the OT could be smaller and less expensive.

Here we go again...
 

Time to get started on my new build, the PSE 8417. I doubt this will ever be an official Inspire offering, since Dennis doesn't like to build commercial offerings featuring hard to source tubes, and 8417's are not just lying around everywhere.

But, I have been looking at this tube for awhile. One might consider it one of the final culminations of the tube designer's art, as it was one of the last developed power pentodes developed before germanium and silicon made tubes "obsolete".
Yes there have been newer tubes developed, like the KT-90/120/150/170, but in my mind these are mere iterations of an earlier design, and not something new and different like the 8417. And since I have a reasonable stash of 8417s, I decided to see what this tube was capable of...

I decided to reuse the Slammer's power supply, albeit upgraded to provide the B+ voltage the 8417 is capable of handling.

However, first order of business was getting the corners welded up and then prepped for cutting/powder coating...

https://live.staticflickr.com/65535/...566844af_b.jpgUntitled by analog addict, on Flickr

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And after a lot more sandpaper mixed with elbow grease, here's one of the welded corners ready for cutting.

https://live.staticflickr.com/65535/...285cd703_b.jpgUntitled by analog addict, on Flickr


However, once I had the chassis ready, I found out that Straitwire was just too busy to cut my chassis, so I was going to have to do it myself. Ugh...The job I like the least when building amps from scratch. So be it.

Next was getting the design laid out for cutting. Dennis gave me a push by getting the first couple of sockets laid out, and then I finished it out.


https://live.staticflickr.com/65535/...2800f97d_b.jpgUntitled by analog addict, on Flickr


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Here's what the topside will look like once put together.

https://live.staticflickr.com/65535/...2be18104_b.jpgUntitled by analog addict, on Flickr


Unfortunately, in the next five weeks, I'll be out of town for three of them, so it will be slow going for awhile.

Stay tuned.

Hmmmmm....Dennis has a BIG pile o 807's lying around the shop. Wonder if he'd consider a PSE 807?

Perhaps.

If you are really interested and he isn't, I could put one together at some point, of course with Dennis' guidance...:thumbsup:

The 807 has become one of my favorite tubes. Well, them and their “equivalents” like vt60, 6bg6, and 5b/254m. I mostly run them in push pull these days. Have been very, very impressed using c3m tubes in triode as drivers. Running the 807 in ultralinear 350v 60ma per tube.

I have gone back to the KT88 Firebottle recently. Right now I am using 6ar6 outputs with a bl63 driver. Wonderful open and warm sound with plenty of bass. You have to use an adapter with the 6ar6 but the tubes are still cheap. Remarkable considering how high a quality tube it is.

Think Globally, act now....
 

Dennis has recently gotten a bee in his bonnet to start playing around with the "old man" tubes again after someone ordered a 45 or a 2A3 amp from him. He has modified the circuit once more and has come to the conclusion that Globe 45's are the best thing since sliced bread.

Gee, I wonder who told him that 5 years ago...:D

Anyway, this is his new amp. The (globally inspired) Fire Bottle SET 45...

https://live.staticflickr.com/65535/...20f864bb_b.jpgUntitled by analog addict, on Flickr


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I believe there will be a small production run of these until they're gone. The 45 SET with ST shaped tubes will be $2750 +S/H and the same amp with globe 45s will be $3150 + S/H and is available in either Inspire Red or High Gloss Harley Black.

PM me to order yours today!!!

I’ve always been intrigued by a 45 based amp but have never had speakers that could even use 2a3 let alone the 45. You must need an incredibly sensitive speaker to use this.

If my status as a tube hipster wasn’t obvious, I have now cemented it with my current combo in my KT88 Firebottle. I am using a Marconi b36 (via an external heater supply) and GEC cv4062 outputs.

I’ve been told that these are related to or in the same family as the el84 but with a different pin out. There was an upper midrange glare with several input tubes but this metal based b36 seems to have mostly tamed that. It is still giving me a very clear sound. I’m not used to sound like this from a single ended amp. It has a precise, clear sound. Still a bit of a metallic sound on some recordings though. I will try the n78 soon, another GEC tube with the same specs.

These particular tubes are another case of the adapters costing more than the tubes. Not sure it’s going to work out for this amp. There are plenty of other tubes I prefer over these and with much less exotic drivers. I’m hoping they will sound better in my push pull amp.

6actually no. Dennis is able to drive all these speakers with his new 45...

https://live.staticflickr.com/65535/...a37c8256_b.jpgUntitled by analog addict, on Flickr

As long at the speaker's efficiency is 90db/w/m, this amp will drive them fine...

Meanwhile Dennis is hoarding all the globe 45s he can find. Toobs are better than money, cause they'll print more money....

https://live.staticflickr.com/65535/...2576a850_b.jpgUntitled by analog addict, on Flickr

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3 of those look like they would be pretty high sensitivity. My speakers are around 90db sensitive and I have gone as low as 4w with decent results. I do think one of the reasons my push pull amp can sound better (depending on tubes) is just having more power.

One of the best systems I have ever heard used a push pull 300b amp. It was a custom amp made by Deja Vu Audio in the DC area and hooked to a pair of Quad ESL63 speakers. Would love to hear some other triodes like the 2a3 or 45 like that.

I have run triode wired 12av5 in my push pull amp. The *av5 tubes have the reputation of being very similar to a 2a3 in triode. Sylvania even sold some wired internally as triodes to the government as 6b4ga which is supposed to be a directly heated tube very similar to a 2a3. They were probably being used in power supplies in measurement equipment or something. Anyway, they sounded really good in my amp both in triode but especially in ultra linear. It would be cool to see what magic Dennis could wrangle out of them both in all the output modes. I'd probably trade my KT88 firebottle towards that if he got something he thought was great.