Sherwood
Headphoneus Supremus
[size=large]Cavalli Compact Tube Hybrid[/size]
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[size=small]DIY[/size] tube hybrid amps are gaining popularity, and it’s not surprising. Capable designers like Alex Cavalli, Ti Kan, Pete Millett and Kevin Gilmore keep coming up with excellent designs, and talented builders on this site keep prototyping them. The appeal lies in the fact that they can have the bass of a solid-state amp with the midrange and tweakability of a tube amp. It’s nice to be able to have the best of both worlds, isn’t it?
The amp I had the fortune of spending the last two weeks with is a great example of all these characteristics. You can stop reading right there, if you like. If you wish to continue, though, there’s a whole 40-page thread on this very amp, including how to build your own, right over here. This is a DIY (Do It Yourself) amplifier, so there are no commercial builders at this time, but Wiatrob built this one for me (well, for me to briefly borrow), and other builders will happily build it for you. That’s enough to qualify it for the main amps page in my view. If you wish to discuss DIY aspects of the amp, please do so in the established thread. If you have end-user questions, here’s the place.
3 things set this amp apart from the competition, and any one of them justifies building one of these, or having one built.
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[size=small]1)[/size] It is really tiny. Almost exactly the same size as the Firestone and Travagan’s family of products.
[size=small]2) [/size] It runs on a single tube, making tube rolling less than half as expensive. “Less than half” because many sellers have wised up, and started charging more for matched pairs of tubes. Take that, opportunism!
[size=small]3)[/size] An innovative tube servo allows this amp to be run off a huge variety of affordable, excellent 9-pin tubes. My review sample came with an RCA 5963 Black Plate, an ECC88 Bugle Boy, a Sylvania 12BH7A, A gold-pinned Amperex 8416, and a 12AU7A clear top. It can also evidently run BQ7A's and 6N1P's. End users are spoilt for choice.
---------------------------------------------------------------------------------
This is just incredibly fun. A wealth of cheap n’ cheerful tubes available to anyone who wishes to find their sound is a real boon, in my opinion. I sincerely enjoyed it, though I tended to find a favorite, and stick with it. For me, I spent most of my time listening to the 5963 and the 12BH7A.
These tubes, unsurprisingly, run at varying voltages. That’s why the amp includes a switch to shift the heater voltage from 12.6v to 6.3v, and a nice protection circuit to allow the tube to warm up before signal is sent through it. Pretty swank, especially for a DIY amp.
That's perhaps enough about the build for a non-DIY forum. The real measure of an amp is never bench tests, it is sound. In deference to this forum’s various musical tastes, I tried to listen to a wide variety of music to ascertain that sound. Of course, it’s all music I enjoy, because I’m doing this for fun. Here's the majority of what I spent my time with:
All songs were ripped in either Flac or 320 kbps Lame, which ran out of my iMac’s Toslink into an Electrocompaniet ECD-1, then directly out of the analog outputs into the CTH, then out to a pair of Grado RS 1 (w/out buttons). This is a rig anyone would be happy to have, and I certainly was.
I’ve always felt that the real virtue of tubes, especially inexpensive tubes, was in their realistic portrayal of acoustic instruments and voices. The CTH really shines in this department. Voices didn’t poke out, as they sometimes do on tubes with accentuated midrange, but rather blended very well into the mix. Nickel Creek’s “Jealous of the Moon” sounded superb, and placed the most emphasis on the standup bass without letting the mandolin overwhelm the 3 part vocals. When Chris Thile moves into his upper registers and his voice starts to break up, it was rendered so sharp as to be almost uncomfortable, but the fiddle above him was as smooth as silk. This is how live music sounds, and it’s wonderful to hear it reproduced. Well done.
The CTH handled male and female vocals equally well, showing a great frequency range throughout the entire vocal range. Ryan Adams sounded every bit as good as Allison Krause, and Troy Sanders (of Mastodon) sounded every bit as gnarly as Cedric Bixler-Zavala (of At the Drive-In).
A common historical complaint against tube amps is anemic bass. I’ve never agreed with it entirely, and I certainly don’t agree with it here. Bass was taut and round-sounding, with fantastic weight. I happen to particularly enjoy the way Grados do bass, however, and the CTH and the RS 1s were clearly meant for each other. The CTH clearly rendered the pitch-shifted didgeridoo and the modified timpani drum on the beginning of Phillip Glass’ Orion. My eyes shook when I turned it up. Does that sound like a tube amp to you? Test tones through a sine-wave generator sounded extremely close to the published frequency chart of the headphones, which leads me to believe that this little amp is capable of putting out far more than the Grados can take. The builder had it configured for his HD650s, and told me that it capably drove them.
I tried to test it on my Stax, but the plug didn’t fit.
Grados are famous for a very intimate soundstage, and so it is no surprise that the CTH and the RS 1s fared very well with combo jazz – in this case, the excellent album Holon by Nik Bartsch’s Ronin. The presentation was spacious, but in a way that put you close to the instruments in a very large room. To me, that means a lot. Decay is long, and background noise is soft enough to allow the notes room to breathe. The flipside of this is that the attack is also very quick, allowing for a wide dynamic range in songs that require it. All of this speaks to an overbuilt amp. Now, it’s not too tough to be overbuilt for Grados, but it’s still delightful to hear. I didn’t have any K701s on hand to test something more difficult, but I have every confidence that the CTH would fare extremely well.
Regardless of what I threw at this amp, it handled it very much to my liking. Massed choral voices, like I tested with Nico Muhly’s album Mothertongues, suffered somewhat. Multitudes of voices had a tendency to slightly smear together, rather than standing out individually.
So what.
Everything I’ve heard anywhere near this price range does exactly the same thing, and it’s likely how people are used to hearing that kind of music. Some tubes also tended to hum somewhat, though since it was equally loud in both ears it was fairly benign. It was audible in extremely quiet passages, but nowhere else. Other tubes were whisper quiet.
The point is, this amp imparted very little character of its own, and sounded like a substantially different amp depending on the tubes used. The tubes I like tended to impart a slightly bassy character to the amp, which is what I enjoy. Different tubes made a different amp, and that is the brilliance of this whole thing. If you want a “straight wire with gain”, put in a tube like the 12BH7A. If you want detail, throw in an 8416. This is really ideal, and is a testament to the quality of this design.
Bottom line, this amp is reasonably cheap, very cheerful, has no need of expensive or matched tubes, has enough power to drive difficult loads, is well-designed enough to benefit from tuberolling, and is small enough to be paired with portable sources. That's an awfully complete package. That it sounds great to boot really seals the deal.
----------------------------------------------------------
[size=small]DIY[/size] tube hybrid amps are gaining popularity, and it’s not surprising. Capable designers like Alex Cavalli, Ti Kan, Pete Millett and Kevin Gilmore keep coming up with excellent designs, and talented builders on this site keep prototyping them. The appeal lies in the fact that they can have the bass of a solid-state amp with the midrange and tweakability of a tube amp. It’s nice to be able to have the best of both worlds, isn’t it?
The amp I had the fortune of spending the last two weeks with is a great example of all these characteristics. You can stop reading right there, if you like. If you wish to continue, though, there’s a whole 40-page thread on this very amp, including how to build your own, right over here. This is a DIY (Do It Yourself) amplifier, so there are no commercial builders at this time, but Wiatrob built this one for me (well, for me to briefly borrow), and other builders will happily build it for you. That’s enough to qualify it for the main amps page in my view. If you wish to discuss DIY aspects of the amp, please do so in the established thread. If you have end-user questions, here’s the place.
3 things set this amp apart from the competition, and any one of them justifies building one of these, or having one built.
---------------------------------------------------------------------------------
[size=small]1)[/size] It is really tiny. Almost exactly the same size as the Firestone and Travagan’s family of products.
[size=small]2) [/size] It runs on a single tube, making tube rolling less than half as expensive. “Less than half” because many sellers have wised up, and started charging more for matched pairs of tubes. Take that, opportunism!
[size=small]3)[/size] An innovative tube servo allows this amp to be run off a huge variety of affordable, excellent 9-pin tubes. My review sample came with an RCA 5963 Black Plate, an ECC88 Bugle Boy, a Sylvania 12BH7A, A gold-pinned Amperex 8416, and a 12AU7A clear top. It can also evidently run BQ7A's and 6N1P's. End users are spoilt for choice.
---------------------------------------------------------------------------------
This is just incredibly fun. A wealth of cheap n’ cheerful tubes available to anyone who wishes to find their sound is a real boon, in my opinion. I sincerely enjoyed it, though I tended to find a favorite, and stick with it. For me, I spent most of my time listening to the 5963 and the 12BH7A.
These tubes, unsurprisingly, run at varying voltages. That’s why the amp includes a switch to shift the heater voltage from 12.6v to 6.3v, and a nice protection circuit to allow the tube to warm up before signal is sent through it. Pretty swank, especially for a DIY amp.
That's perhaps enough about the build for a non-DIY forum. The real measure of an amp is never bench tests, it is sound. In deference to this forum’s various musical tastes, I tried to listen to a wide variety of music to ascertain that sound. Of course, it’s all music I enjoy, because I’m doing this for fun. Here's the majority of what I spent my time with:
All songs were ripped in either Flac or 320 kbps Lame, which ran out of my iMac’s Toslink into an Electrocompaniet ECD-1, then directly out of the analog outputs into the CTH, then out to a pair of Grado RS 1 (w/out buttons). This is a rig anyone would be happy to have, and I certainly was.
I’ve always felt that the real virtue of tubes, especially inexpensive tubes, was in their realistic portrayal of acoustic instruments and voices. The CTH really shines in this department. Voices didn’t poke out, as they sometimes do on tubes with accentuated midrange, but rather blended very well into the mix. Nickel Creek’s “Jealous of the Moon” sounded superb, and placed the most emphasis on the standup bass without letting the mandolin overwhelm the 3 part vocals. When Chris Thile moves into his upper registers and his voice starts to break up, it was rendered so sharp as to be almost uncomfortable, but the fiddle above him was as smooth as silk. This is how live music sounds, and it’s wonderful to hear it reproduced. Well done.
The CTH handled male and female vocals equally well, showing a great frequency range throughout the entire vocal range. Ryan Adams sounded every bit as good as Allison Krause, and Troy Sanders (of Mastodon) sounded every bit as gnarly as Cedric Bixler-Zavala (of At the Drive-In).
A common historical complaint against tube amps is anemic bass. I’ve never agreed with it entirely, and I certainly don’t agree with it here. Bass was taut and round-sounding, with fantastic weight. I happen to particularly enjoy the way Grados do bass, however, and the CTH and the RS 1s were clearly meant for each other. The CTH clearly rendered the pitch-shifted didgeridoo and the modified timpani drum on the beginning of Phillip Glass’ Orion. My eyes shook when I turned it up. Does that sound like a tube amp to you? Test tones through a sine-wave generator sounded extremely close to the published frequency chart of the headphones, which leads me to believe that this little amp is capable of putting out far more than the Grados can take. The builder had it configured for his HD650s, and told me that it capably drove them.
I tried to test it on my Stax, but the plug didn’t fit.
Grados are famous for a very intimate soundstage, and so it is no surprise that the CTH and the RS 1s fared very well with combo jazz – in this case, the excellent album Holon by Nik Bartsch’s Ronin. The presentation was spacious, but in a way that put you close to the instruments in a very large room. To me, that means a lot. Decay is long, and background noise is soft enough to allow the notes room to breathe. The flipside of this is that the attack is also very quick, allowing for a wide dynamic range in songs that require it. All of this speaks to an overbuilt amp. Now, it’s not too tough to be overbuilt for Grados, but it’s still delightful to hear. I didn’t have any K701s on hand to test something more difficult, but I have every confidence that the CTH would fare extremely well.
Regardless of what I threw at this amp, it handled it very much to my liking. Massed choral voices, like I tested with Nico Muhly’s album Mothertongues, suffered somewhat. Multitudes of voices had a tendency to slightly smear together, rather than standing out individually.
So what.
Everything I’ve heard anywhere near this price range does exactly the same thing, and it’s likely how people are used to hearing that kind of music. Some tubes also tended to hum somewhat, though since it was equally loud in both ears it was fairly benign. It was audible in extremely quiet passages, but nowhere else. Other tubes were whisper quiet.
The point is, this amp imparted very little character of its own, and sounded like a substantially different amp depending on the tubes used. The tubes I like tended to impart a slightly bassy character to the amp, which is what I enjoy. Different tubes made a different amp, and that is the brilliance of this whole thing. If you want a “straight wire with gain”, put in a tube like the 12BH7A. If you want detail, throw in an 8416. This is really ideal, and is a testament to the quality of this design.
Bottom line, this amp is reasonably cheap, very cheerful, has no need of expensive or matched tubes, has enough power to drive difficult loads, is well-designed enough to benefit from tuberolling, and is small enough to be paired with portable sources. That's an awfully complete package. That it sounds great to boot really seals the deal.
