[dls123]

To continue...
   Once you get used to listening to the circuit topology used in the Raven and the Blackbirds, you find it hard to listen to anything else.  Not that there are not a lot of great amps and preamps in the world that use other sorts of circuits, but this particular fully balanced approach has a certain sound.  Actually, it is not really a sound per se, but rather a transparency that is the result of removing and cancelling distortion and feedback that is in most other designs, including many I have worked on and built myself.  When you remove all the subtle grunge and greyness caused by other circuits and approaches, cap colorations, etc... you get a very open and airy sound that is tonally correct.  It makes all the other circuits sound just a bit veiled or gray.  The piano sounds like a piano and it is in the room if the rest of your system can do it.  Lynn likes to say the tone colors are vivid. 

 There is a long 300b lovers thread on another board and also one on the Raven preamp.  You can find them if you search a bit.  I chuckle because there is a well known manufacturer who inserts himself quite often, even on the Raven thread, which is specific to the Raven preamp.  His contention is that there are modern Class D amps the are as good as the best tube amps.  I have not heard his particular class D amp, but I have heard a few quite good ones.  They do indeed rival good tube amps at most things.  But not THESE tube amps.  The class D amps I have heard cannot touch the Blackbirds, or a pair of lower powered 45 based push pull monos using the same circuit that I built as a project for a friend with very efficient speakers.  Lynn's circuit, when properly built with custom parts, produces a tonal correctness that I have not ever heard before from any amp, even the best tube amps I have experienced.  Other amps get close, but they do not get it quite right.  You don't realize this until you live with these amps for a few months and then listen to something else.  You find that the instruments and voices don't sound quite right.  This approach yields a clarity that I have never heard before.  They are totally transparent, but not bright at all.  There is subtle detail and shading you get used to.  You can listen all day long.  The Raven is the same because the circuit idea is the same.  Once heard, it cannot be "unheard" and so far, nothing else quite stacks up for me....

[jnschneyer]

To continue...
   Once you get used to listening to the circuit topology used in the Raven and the Blackbirds, you find it hard to listen to anything else.  Not that there are not a lot of great amps and preamps in the world that use other sorts of circuits, but this particular fully balanced approach has a certain sound.  Actually, it is not really a sound per se, but rather a transparency that is the result of removing and cancelling distortion and feedback that is in most other designs, including many I have worked on and built myself.  When you remove all the subtle grunge and greyness caused by other circuits and approaches, cap colorations, etc... you get a very open and airy sound that is tonally correct.  It makes all the other circuits sound just a bit veiled or gray.  The piano sounds like a piano and it is in the room if the rest of your system can do it.  Lynn likes to say the tone colors are vivid. 

 There is a long 300b lovers thread on another board and also one on the Raven preamp.  You can find them if you search a bit.  I chuckle because there is a well known manufacturer who inserts himself quite often, even on the Raven thread, which is specific to the Raven preamp.  His contention is that there are modern Class D amps the are as good as the best tube amps.  I have not heard his particular class D amp, but I have heard a few quite good ones.  They do indeed rival good tube amps at most things.  But not THESE tube amps.  The class D amps I have heard cannot touch the Blackbirds, or a pair of lower powered 45 based push pull monos using the same circuit that I built as a project for a friend with very efficient speakers.  Lynn's circuit, when properly built with custom parts, produces a tonal correctness that I have not ever heard before from any amp, even the best tube amps I have experienced.  Other amps get close, but they do not get it quite right.  You don't realize this until you live with these amps for a few months and then listen to something else.  You find that the instruments and voices don't sound quite right.  This approach yields a clarity that I have never heard before.  They are totally transparent, but not bright at all.  There is subtle detail and shading you get used to.  You can listen all day long.  The Raven is the same because the circuit idea is the same.  Once heard, it cannot be "unheard" and so far, nothing else quite stacks up for me....

I just wanted to say that I love this description of the sound of the 300B and Raven preamp.  I've never heard either - I own the Valhalla and X5s - and I'm not sure, until I can afford them, that I want to, as I'm afraid it would make me unhappy with my current setup.  But I love the simple, clear, hypeless description of the sound enough to say so.  That's it.

[rfluongo]

Only been a few hours but can't help posting a teaser. I had been without a preamp running DAC's analog VC straight into LTA ZOTL40 with (I thought) very good results. Speakers are GR Reasearch NX-Otica. Adding the Raven proves that more is more in this case - clarity, body, space. More to come...

[dls123]

@rfluongo
Glad you like the Raven.  I have done numerous experiments over the years building little passive preamp experiments with killer attenuators, and running DACs direct to amp.  My preamp sounds better every time.  The Raven is the best preamp I have built or heard to date.   I have to laugh when people argue with me that less is more and running your DAC directly to the amp sounds better.   It has never sounded better to me.  But perhaps they are using lesser preamps.  The Raven can take your XLR DAC output and run it directly XLR to your amp if your amplifier is fully balanced and has xlr inputs.   Anyway, have fun.  Your Raven will improve for about 50 hours or so as the big cathode bypass caps run in.  Usually by 20-30 hours things really open up.

Wish I could swap the Blackbirds in there instead of the LTA for an hour:)

[dls123]

I just wanted to say that I love this description of the sound of the 300B and Raven preamp.  I've never heard either - I own the Valhalla and X5s - and I'm not sure, until I can afford them, that I want to, as I'm afraid it would make me unhappy with my current setup.  But I love the simple, clear, hypeless description of the sound enough to say so.  That's it.

I hate hype and audiophile mumbo jumbo.  Honestly, I built this preamp and 300b amp combo on a dare from Lynn, and as I said above, it was a 3 year odyssey.  I basically did it to hear what was possible and get the best stereo I could in my living room.  It has a space and ease and musicality that I have not heard even in $100K+ rooms at audio shows.   Except in the Spatial room where the Raven and Blackbirds were driving Sam's Q3.  I just wish more folks could hear it.....

[rfluongo]

Wish I could swap the Blackbirds in there instead of the LTA for an hour:)

Would love to hear the Blackbirds but my amp real estate is limited to what you see in the pic. Any chance of a stereo "Blackbird Jr." with more of a Raven footprint? 

[dls123]

Would love to hear the Blackbirds but my amp real estate is limited to what you see in the pic. Any chance of a stereo "Blackbird Jr." with more of a Raven footprint? 

There will most likely be a stereo amp in the 25 watt/ch range that borrows a lot of the ideas in the Blackbirds.   It will have compromises in terms of power supply and will run your typical indirect heated output tubes, most likely a KT88 in triode, and it will certainly be a fully balanced design.  You cannot fit 4 big DHT output tubes in a stereo amp without a lot of heat, or compromises in the power and filament supplies.  That is why most of the stereo 300b amps you see are either very large, or they use small signal tubes in the driver section, or they just aren't very good amps. 

 Don't expect to see a finished product before next summer or fall though.   I would expect it to be a very good amp.  It will not be the Blackbirds, but should sound very good, especially with a Raven in front of it.  It will happily drive any of Spatial's speaker offerings.  But there is no exact timetable.  It is in very early prototyping now, as in Lynn and I know the design, but I haven't built a prototype yet!

[sonicboom]

I've been wanting to build Lynn's Karna amps for the last 15+ years, but it's not an easy project to undertake. I am glad that you took on the challenge and by all accounts it seems you have succeeded - so congrats to all involved for bringing both amp and preamp to market.

As concerns the amp, I will admit that I did not expect the KT88 to prevail as the driver of choice. Not that I am doubting the results or second guessing the design choice as I'll assume that many types were tried in this position before settling on this tube.

The only thing that I would've liked to have seen here, is the inclusion of damper diodes for rectification as in the original design. Especially since these are mono blocks with a bit more real estate inside the chassis.

[dls123]

I've been wanting to build Lynn's Karna amps for the last 15+ years, but it's not an easy project to undertake. I am glad that you took on the challenge and by all accounts it seems you have succeeded - so congrats to all involved for bringing both amp and preamp to market.

As concerns the amp, I will admit that I did not expect the KT88 to prevail as the driver of choice. Not that I am doubting the results or second guessing the design choice as I'll assume that many types were tried in this position before settling on this tube.

The only thing that I would've liked to have seen here, is the inclusion of damper diodes for rectification as in the original design. Especially since these are mono blocks with a bit more real estate inside the chassis.

Hi
Thanks for your comments!  Damper diodes just are not practical in the amp as you would need many of them.  There are two full wave power supplies.  The preamp only has the one supply.  The regulated supplies isolate any nastiness from diodes quite well.   As for the drivers, the KT88 in triode was easily the best.  A 45 tube is impractical because they are $1000+ per pair for the really good modern production ones, and there are only one or two reliable manufacturers.  There are other DHTs that would work, but they are old stock tubes.  So again, supply is not guaranteed.  We wanted to build a preamp and amps that used tubes in current production.  The 6SN7, KT88, 300b are all easily obtained and there are fine examples of each being made by multiple manufacturers.   The damper diodes and VR tubes are not in production, but there are thousands for sale for very low prices, and they last for years.  So that won't be a problem for an owner.

So again, if I were building a single pair of amps for myself, and I didn't care about a reliable supply of tubes because I had enough of a stash for a lifetime... well then maybe other choices.  But in a commercial product.....   I am happy the way both pieces turned out:)

[dls123]

Also... the KT88 is a superb tube.  It is often misused, in UL circuits with lots of feedback.  So you never really hear what it can do.   If you run them in triode, class A balanced pair, they really shine as a driver. 

[sonicboom]

Hi
Thanks for your comments!  Damper diodes just are not practical in the amp as you would need many of them.  There are two full wave power supplies. 

So again, if I were building a single pair of amps for myself, and I didn't care about a reliable supply of tubes because I had enough of a stash for a lifetime... well then maybe other choices.  But in a commercial product.....   I am happy the way both pieces turned out:)

It's understandable, commercial considerations often dictate design choices. Having eight damper tubes per chassis for the two FWB rectifier circuits is a bit much, also compounded by the fact that their filaments are quite heavy on current draw.

Also... the KT88 is a superb tube.  It is often misused, in UL circuits with lots of feedback.  So you never really hear what it can do.   If you run them in triode, class A balanced pair, they really shine as a driver. 

That's good to know as the '88 being a large 40W plate dissipation tube, is not what first comes to mind as the driver for another 40W dissipation tube, i.e. the 300B. Thanks for pointing this out, I'll keep it in mind going forward.

[Mr. Big]

@rfluongo
Glad you like the Raven.  I have done numerous experiments over the years building little passive preamp experiments with killer attenuators, and running DACs direct to amp.  My preamp sounds better every time.  The Raven is the best preamp I have built or heard to date.   I have to laugh when people argue with me that less is more and running your DAC directly to the amp sounds better.   It has never sounded better to me.  But perhaps they are using lesser preamps.  The Raven can take your XLR DAC output and run it directly XLR to your amp if your amplifier is fully balanced and has xlr inputs.   Anyway, have fun.  Your Raven will improve for about 50 hours or so as the big cathode bypass caps run in.  Usually by 20-30 hours things really open up.

Wish I could swap the Blackbirds in there instead of the LTA for an hour:)

I have never heard system that sounds better without a good preamp and I've tried several times to run direct to my amp bypassing the preamp. Nada not once was it better and not even close.

[Early B.]

I have never heard system that sounds better without a good preamp and I've tried several times to run direct to my preamp bypassing the preamp. Nada not once was it better and not even close.

Me, too. Not sure how some people can say a preamp isn't necessary. If that were true, most hard-core audiophiles would eliminate them. These new all-in-one streamers are trying hard to replace separates based on sound quality, but it won't happen.

[dls123]

Me, too. Not sure how some people can say a preamp isn't necessary. If that were true, most hard-core audiophiles would eliminate them. These new all-in-one streamers are trying hard to replace separates based on sound quality, but it won't happen.

Hence the Raven:)