Review: Classe Five preamplifier

 
Introduction:
Given my heavy valve past going with an upscale solid-state preamplifier was a difficult choice.  Though certainly not a heart-wrenching one as I do have more recent experiences with Threshold, Adcom, and even some homebrew gear.  And since I was considering going all separates, different preamps for both phono and line, my choice to buy a full-function Classe 5 may also be a puzzling one.

Classe, however, is one of those companies that have been on my radar ever since I was a twenty-something reading Absolute Sound and Stereophile.  Back then Classe was considered very "tube-like" and warm, completely opposite to the common complaint of much solid-state gear: harsh or strident, especially in the treble region.  Such descriptions, like the warm sound of early Mac SS gear, piqued my interest.  But since I was a poor college student, living on a diet of vintage tube amps, Mac 'n' Cheese, and $2.99 records, anything in the price range of a Classe DR-5 or DR-6 preamplifier was unthinkable. So instead I soldiered on with DIY gear, plenty of Dynaco PAS preamps, and an Eico HF-85.

Well doesn't time fly?  Perusing through the Audiogon ads, I saw a recently listed Classe Five preamplifier.  It had a phono stage, switchable from MM or MC cartridges, and even a remote control.  Their isn't much information out there on the Five but some search engine sleuthing and I found it is essentially an upgraded 1990s version of the original DR-5.  It also features balanced (XLR) or single-ended (RCA) outputs; a single set of balanced inputs too if I ever needed them.  The XLR outputs will come in very handy for my planned bridged ACA amplifiers that are being built sometime very soon.

With the price being right, I put an offer in and it was accepted.  Given the proximity of the seller, I received the preamplifier the next day.  Unpacking the Classe Five and I found myself with a very heavy duty unit that was nearly flawless.  The switches, which have a wonderful tactile feel, worked perfectly, as did the remote control and the various knobs.  The wireless remote has buttons that causes little motors on the volume and balance to physically turn the knobs.  Very neat (I'm still an adolescent at heart!).  This is also great for adjusting the gain to get that perfect playback level from the comfort of my favorite listening chair.

Initial Impressions:
It is always exciting to listen to something new - but the Five wasn't exactly earth shattering.  The sound was dark, a bit muffled, and seemingly missing some bite on the top end.  Bass, however, was controlled and the overall sound was smooth.  With only an hour or so of time, I went to bed, leaving my new preamplifier in standby mode since there is no power off button.

The next day, after work, I heard an improvement in sound.  The smoothness was still there but everything sounded a lot more cohesive.  I fought the urge to do any serious listening, waiting for a quiet Sunday afternoon where I could experience the Classe Five without any familial distractions.



In my doddering middle-age I've become a bit of a Chet Baker fanatic, even exploring his musical output beyond his 1950s heyday.  Nonetheless I still have an appreciation for his signature album, Chet.  It's a brooding masterpiece that has the fingerprints of Bill Evans all over it.  Listening to this album - 1980s Riverside pressing - reveals a lot more detail than I was hearing through the Adcom GFP-555.  The Classe Five does a better job of revealing the light cymbal work, which sounds deeper in the soundstage but with the attack and decay being more apparent as is the metallic nature.  Too many systems turn cymbals into a hard SHHHH noise, instead of the shimmering, complex sound it should be.

Instrument - piano, the brass instruments, and drum - have a more natural body than my old preamplifier.  The overall sound is very smooth but doesn't inhibit the more aggressive tones of the music.  It is a different type of smoothness than I ever heard; not imbued with a golden hue like a vintage tube preamplifier but more as if the sonics were cut from a single, grain-less cloth. 

Willie Nelson has a rich and immediately familiar voice.  On Stardust, the vocals come across as completely natural with just a hint of studio reverb added.  The instruments remain firmly behind the singer, reproducing the very intimate nature of this album.  Tonality is some of the best I heard, exceeding my expectations given the budget nature of the speakers and my turntable and cartridge. Cohesiveness is another word that came to mind, and one that kept popping up as made notes.  No single instrument seemed crowded out while another took the center of attention.



For something more dynamic, I turned to one of the greatest live blues albums ever recorded: Drinkin' TNT 'n' Smokin' Dynamite which has an all star backing band behind Buddy Guy and Junior Wells.  The Classe Five captured the audience background noises allowing me to place them in location and distance from the stage.  The dynamic shifts, given the limitations of the Wharfedale Denton speakers, were impressive; never sounding bloated or blurred.  An example of this is the stuttering starts and stops of the lead guitar, along with the deep bass foundation.  Each instrument had its own space but jelled together as one whole, making for a very toe-tappin' experience.


After that good time, I needed a melancholic change of pace.  Richard and Linda Thompson deliver this in spades with their album Shoot Out the Lights.  Linda's voice is sublime here, all barely hidden pain while the barbed wire guitar of Richard grinds away as if stripping the heart out of his troubled marriage.  His backing vocals sit separate from hers, as if he is giving his ghostly agreement.  This album, needless to say, a heart-wrenching series of songs.  The Classe Five does an excellent job of baring these emotions.





I listened to several other albums of varying quality - like The Fixx, Wardruna, The Police, and even some old 1930s-era Billie Holiday.  Poor recordings sounded like, well, poor recordings.  And mediocre ones weren't given any extra magic either.  The Classe Five appears to be rather neutral, low in coloration, and even-handed.  This one is a keeper.


Takeaways:

The Classe Five has the best treble I have ever heard from a solid-state preamplifier.  At first I thought it was rolled-off; lacking in air and excitement.  However further listen revealed that it is actually a lack of glare and edginess that is often common in lesser solid-state gear.  If a recording is bright, you will hear that.  If it is dull, or poorly recorded, that will be revealed.  There is no heavy coloration going on here.

Along with this natural treble comes the feeling, from top to bottom, that all frequency points are sonically similar; that is to say no part of the sound, be it treble or bass, sticks outs or draws attention to itself.  As I mentioned above, everything is cut from the same sonic cloth.  It's something I never quite heard to this degree with any preamplifier that I've ever owned and took some time to understand this new experience.  A similar situation occurred when I first heard the VPI Aries 1, only then did I hear the warble and background rush of lesser turntables.

Bass control is excellent - tight and dynamic without any bloat or smear.  This is essential for providing the foundation of the song.

Detail is very good; though some listeners may prefer a more hyper detailed presentation.  Perhaps this is the limitation of my front-end or the nature of the Wharfedale speakers.  Some future upgrades will see how well this holds true.

The quality of the Classe Five makes me question, to some degree, my allegiance to valves.  At least with valve gear you can roll in different tubes to find the best match with your system.  But, if you're tired of buying high priced NOS valves or even new stock, then give the Classe Five a try. You may be surprised.


System:
Adcom GFA-545 amplifier
Dual CS5000 turntable with Ortofon OM20 phono cartridge
Pioneer DVD-V7400 DVD player
Kimber 8PR/4PR bi-wire speaker cables
various budget interconnect cables

Review: Wharfedale Denton 80th Anniversary speakers

 

Introduction: I've been running with B&W Matrix 805 speakers for almost five years now.  They are good speakers but after such a long time I was interested in trying something new.  I first started concentrating on finding some KEFs, which is a speaker brand that I've always liked.  I had my eye on a pair of LS50s, Reference 1s, or even some small Q towers.  Instead I was drawn to a Wharefedale Denton review on the Steve Hoffman forums which had several fellow audio nuts being in love with this speaker.  One of them even sold his KEF LS50s and stayed with the Denton speakers. Given the low clearance price of these speakers I decided they were worth a try.

 

The Wharfedale Denton is a small mini monitor sporting a 5" Kevlar woofer and a 1" textile dome tweeter, something you would find out of an 1980s speaker.  These particular units, with an original cost of $1000USD, were created for Whardale's 80th anniversary and as a homage to the original vintage version.  Sensitivity is only 86dB so low-powered amplifiers may have trouble driving them.  The speakers can be bi-wired via the gold binding posts outback.  Bonus - prices have dropped considerably with this speaker, now they can be purchased new for $400USD.

I bought my pair of Dentons used so they were already broken in.  The original Wharfedale box arrived quickly and without any damage.  Packing was excellent and the little cloth bags surrounding the speakers was a nice touch.  Build quality appears to be very high.  Rapping on the side of the cabinets gives a high "tink" instead of low, hollow "thunk" which reveals some heavy construction.  The veneer / wood combo and silver grille looks quite presentable in my mid-century modern furnished house.  Very high - at least in this domicile - wife acceptance factor.

After removing the Matrix 805s and associated line-level bass equalizer, I plunked the Wharfedale's on top of the speaker stands.  I then moved the speakers a little further out into the room.  Since I already had some Kimber 8PR/4PR cables in place I decided to bi-wire.  Amplification is the soon-to-be replaced Adcom GFP-555 preamplifier and GFA-545 amplifier while the front end is the Dual CS5000 with the soon-to-replaced Shure M97xe phono cartridge.  As you can tell, I'm in the middle of a system rebuild so stay tuned for further developments.  But right now this is a decent budget system, something that someone who has $400USD to spend on speakers might have.

Listening: Initial thoughts - a little boxed in sounding.  A little flat and very polite.  But these speakers were literally winter cold having sat in a UPS truck and on my doorstep for a few hours before I set them up.  After running some errands, and with a fully warmed up stereo, I finally sat down to do some serious listening.

One of the groups I've been collecting lately is The Police.  I now have all of their albums on Japanese pressed vinyl, but for this session I went with 12" British-pressing single of Wrapped Around Your Finger.  This is a really excellent sounding cut of this song, besting my LP version.  On the Wharfedales the bass had a lot of PRaT, laying down a solid foundation that only increased the enjoyment of this song.  Dynamics, considering the size of the woofer, was impressive.  I've heard similarly sized woofers in KEF and other speakers that get muddled in this part of the spectrum.  Perhaps there is some mid-bass hump here at play but it was still tight and well-done without any overhang.

The all important midrange was clean and lively with a touch of warmth.  Vocals sounded natural as did the other instruments.  Each sat in it's own space without sounding confused.  This made it easier to pick out the different threads of the song.  With the narrow front baffle, the Denton speakers also did a more than fair job at disappearing, only leaving a good left-to-right stereo spread.

The treble on this 12" cut was clean though perhaps a bit rolled-off.  Very British polite, if I do say so myself.  The brashness of the cymbals were muted, though to what degree would require further exploration.  But the first impression was of a very listenable speaker that didn't sound forward or overly bright.  That can be a difficult thing for many small speakers since the temptation for manufacturers is to make a speaker that has a lot of fake detail by having a tipped-up response.

Dan Bejar is the talented singer-songwriter that fronts Destroyer.  Kaputt may be the best realization of his vision: idiosyncratic lyrics mixed with breathless delivery, all held together by a tight multi-instrumented backing band.  It reminds me of the lighter moments of Roxy Music mixed with free form poetry.

On the Denton speakers the music jelled together very nicely, making a cohesive picture that allowed me, to repeat myself, hear the different threads of the song but experience them as a whole.  Bass, once again. was very tuneful.  The midrange was smooth as was the treble.  I also noticed some extra detail retrieval that I hadn't heard before with the Matrix 805s speakers.  With the Dentons there was some synth that was low in the mix, along with extra breathiness in the backup vocals.  I've heard this album many, many times so this extra detail came as a bit of a surprise.  Nor was it hyped up detail from a bright treble, but instead seemed a completely natural part of the song.  Color me impressed.


 It was time to try an album that I am very familiar with, one that I have heard across several systems - a British pressing of Supertramp, Crime of the Century.  The lead in song, School, is bombastic with very deep bass and explosive dynamic contrasts.  How does the Wharfedale hold up compared to my departed UREI 813A speakers, which could really deliver the goods?  In a word (or three), not so well.

The deepest bass here - and there is a lot of it - becomes rather one-note and plodding, missing out on the subtle shadings I hear on much larger speakers.  The same was true with the dynamics which did not have the swell and force it should have had.  This is hardly a surprise given the physics of a 5" woofer; after all there is only so much air that it can move.  An added subwoofer would really help out here.  It really was surprising how nice the bass sounded on the Police cut versus the Supertramp track, showing the physical limitations of the small woofer on some material.

The midrange and treble, however, were still very pleasing but the muddiness of the bass did distract from the overall presentation.  Depth was foreshortened compared to the best I've heard, but the left-to-right stereo spread was marvelous.

A non-audiophile favorite of mine is John Moreland's High on Tulsa Heat.  The simpler tracks, which feature John's emotional voice and guitar, sounded pretty satisfying.  I was reminded of the time I saw him play live at the Ark in Ann Arbor.  The full band songs, however, were dark sounding and lacked air and detail.  I put the blame on the home studio recording equipment and microphones used, but just to be sure I listened to some brighter albums to see if they were noticeably rolled off on the top end.

The Stranger Things Volume 2 soundtrack is nothing but synth music made in a retro-70s style.  The higher frequencies were well-controlled and didn't display any massive roll-offs.  I would expect this to be a tad brighter than what I heard but not by much. 

Next up was The Blue Nile - A Walk Across the Rooftops, which features swooping synths and austere guitar work.  The top end was prominent but a small touch of top end loss was still apparent to these middle-aged ears.  It is obvious that this treble roll-off was an intentional design decision, made to replicate the sound of more vintage speakers.  So the Dentons are not the most accurate of speakers but a flaw that I can live with given the rest of the system budget.

Conclusion: In the sub-$1000USD range, the Dentons are the best that I've heard - period.  Highly recommended.

Life is about compromise, and speakers are among the worst in this regard.  The reality is that when dealing at this price range, it takes a lot of first-class engineering and careful listening to make a speaker work this well.   These are transducers that carry the music in an engrossing, melodic fashion.  Poised is the word that comes to mind, making lesser speakers in this cost bracket sound positively brash and unsophisticated.  The toe-tapping enjoyment I get from the Wharfedales make their sins ones of omission, which though are many, mostly fade into the background.

Limitations?  Many.  These are not party speakers. If you want something that rocks and plays harder, I would suggest you research any number of larger brands and models; especially something with a bigger woofer.   Another option is to add a subwoofer.  If you need even more finesse or bandwidth, then you're looking at spending more money.  The Denton speakers are well-balanced for their size, drivers complement, and price point but there are a lot of possibilities out there for better sound.  We shall be exploring these as my system changes.  But for now I will stick with the Denton speakers and see how they respond with tube amplification and a better phono cartridge.  Stay tuned!

System:
Adcom GFP-555 preamplifier
Adcom GFA-545 amplifier
Dual CS5000 turntable with Shure M97xe phono cartridges
Pioneer DVD-V7400 DVD player
Kimber 8PR/4PR bi-wire speaker cables
various budget interconnect cables

Update: The replacement of the Shure cartridge with an Ortofon Super OM 20 really broadened the bandwidth of the Wharfedale speakers.  Treble no longer sounds rolled off and bass -within middling listening levels - has a lot more composure.  It's a nice little match.  See the Ortofon review for more details.

Review: Nagaoka MP-110 phono cartridge

Since my Audio Technica AT95E phono cartridge mysteriously suffered a cantilever bend, and, even after adjusting for this minor metal tweak, began to suffer from bothersome inner-groove distortion, I thought it was time for something new.  With the B&W speakers and the very nice (for the price) performance of the Nakamichi SR-3A receiver, I wanted a decent jump up in sound quality.  In the sub-$100 category, there are several popular choices - the Ortofon OM10 and 2M Red, the Audio Technica AT-100E and AT-110E, the Shure 97xE, the Sumiko Oyster, and two Grado cartridges.

One brand, however, begin to stick out, Nagaoka.  They offer several models ranging from the $80 MP-100 to the $655 MP-500.  Since this is a budget rig, I decided on the MP-110 with its strong 5mV output, a reputation for tracking and low noise, and the replaceable stylus.  The cartridge came in a funky little UFO-shaped container along with screws and even a little screwdriver.

A quick visual inspection showed a cantilever that was mounted straight without any slop to the left or right.  Construction quality was high - it felt more substantial than the budget Audio Technica AT95E - though some threaded holes would be nice instead of juggling with tiny nuts and screws (please no sexual jokes).  Installation on my Dual CS5000 removable headshell wasn't too bad, provided my big Norgie cat stopped getting in the way.  Apparently she likes shiny things.  After that a protractor was used for alignment and digital gauge to determine the stylus force, which was set at 1.8g.

With no break-in, the sound was a little strange - diffuse and with some minor midrange suckout.  Tracking, however, was very, very good.  With some cartridges, the MFSL re-issue of Frank Sinatra - Nice 'n' Easy, the last track could start to show some serious inner-groove distortion.  Listening intently with the Nagaoka I had a hard time hearing any mistracking or added grittiness to the vocals.  Very impressive considering the low price point of this cartridge.

A few hours and many records later it was time to do some serious listening.

Listening to the re-issue of Dead Can Dance - The Serpent's Egg revealed a cartridge that sounded surprisingly refined for this price level.  The midrange was on the warm sound of neutrality and the treble was slightly forward with a bit of a metallic sheen, but the music was reproduced without any of the roughness or congestion that I normally associate with cheap cartridges.  Bass definition - at least through the small woofers of the B&W Matrix 805s - was very good.  It was also easy to pick out the different instruments in the mix. 

One of my rarer records is the album Turquoise Fields from the French Coldwave act Little Nemo.  My copy isn't exactly mint and normally has some offending ticks and pops that distract from the music.  The Nagaoka MP-110, however really reduces this noise quite a bit.  I also found this to be true with my beat up Japanese copy of This Mortal Coil - It'll End In Tears.   In short, the cartridge is a godsend for vinyl collectors of obscure music who can't always find the cleanest copy.

My second system is mainly used for background - not for serious listening.  The speakers are too far apart and too close to the wall for good imaging.  The soundstaging, therefore, is not a strong point.  I can't comment too much on the Nagaoka MP-110 here, but the imaging is a bit diffuse and a little less solid than my CD player.  I am, however, too lazy to install this cartridge in my main system, replacing the Dynavector 10X5.  Maybe someday once the Dynavector needs to be re-tipped.

Nonetheless, I can highly recommend the Nagaoka MP-110 within the confines of a budget system.  That refinement I mentioned earlier gives a real "taste of the high-end".  In comparison, my memory of the Ortofon 2M Red (on a different table, mind you) was of a rougher sound.  This finesses of the MP-110, and the ability to reduce vinyl noise while tracking the inner groove makes it a budget winner.

Second System:

Dual CS5000 turntable

Pioneer DVD-V7400

Nakamichi SR-3A receiver

B&W Matrix 805s on stands

Wire: Various brands

Dividebytube's Guide to Building an Audiophile System

I've been into this hobby for a number of years and have gone down several dead ends.  This little article is a sort of "lessons learned" piece, which may be of some benefit to a beginner - or even an experienced - audiophile.

Consider the Source:
Like Linn, I believe having a good signal source is the most important part of any good stereo system.  Some others will tell you to spend the majority of the budget on speakers, or even the amplifier.  However, I've found a cheap CD player or turntable will just lead to heartache, making the listener chase their tail trying to find the best speaker or amplifier to match with the inferior sound quality.  Is the speaker too bright or is it the cruddy op-amp in the digital-to-analog converter?  Is the amplifier muddy or does the turntable poorly constructed, picking up vibration?  A fairly neutral source provides the foundation for good system building.

Amplifier Envy:
This idea is closely related to the first concept of source quality - don't go crazy with finding "the right" amplifier until you have nailed down your front end.  Yes, just the right amplifier does make a big difference, especially tubes versus solid-state or Class A versus Class AB, but don't worry about this aspect as much until you have sorted out the source and the speakers.  There are plenty of budget models out there that will do the job until the time is right for an upgrade.

Boom and Sizzle:
Speakers are like luggage - easy to buy and almost impossible to sell.  Before buying any speaker, consider your listening room, environment, and music likes.  For example, a small space will require a small speaker - there is no reason to excite room nodes and get a muddy sound with a monster speaker crammed inside of a tiny space.  If you have little children - a Quad Electrostat or a mini-monitor on a slender stand - may not be the best route.  And small speakers may not reproduce bass all that well, which won't work for head-banging levels, unless a subwoofer is used.

Picking an Amplifier:
I like tube amps, especially single-ended and/or low-powered ones.  Good sounding amplifiers of a higher wattage are few in number, but they do exist.  The Eico HF-60 and (rebuilt correctly) Dynaco Mark III monoblocks come to mind.  However one has to be smart enough to realize that tube amplifiers may not always be the best match for the speaker, especially if low-efficiency, wild impedance curves, or a large listening space is being used.  In this case, perhaps a bigger tube amp or a good solid-state unit is in order.  For example, matching a 20W 6BQ5 amplifier to a pair of Magnepans will lead to nothing but frustration, unless incredibly low playback levels are your thing.

The Good, The Bad, and the Feedback:
Zero Negative Feedback and single-ended was quite the rage for awhile.  However, these types of amplifiers require efficient speakers with higher impedance curves - think Altec-Lansing horns, Klipsch, or (modern) Zu speakers.  Pairing a single-ended 2A3 amplifier to a 4-ohm nominal speaker can result in some strange effects: muddy, underdamped bass or perhaps a rolled-off treble.  Some listeners may like this effect, but it isn't fidelity since the "romantic" tubey sound can dominate the music to the point where the differences between recordings becomes almost negligible.  That is to say, if every record or CD sounds the same, then you're listening to a pleasant distortion machine, not a high-fidelity amplifier.  In this case feedback - if judiciously applied - can actually help, providing speaker damping and extending frequency response.

Short Circuit:
Another strange audiophile fancy is the love for boutique parts.  Now don't get me wrong, I've personally heard differences between coupling capacitors, resistors, and wire.  But I also know that the circuit itself is the most important part, not the parts supporting it.  For example, a poorly design SRPP tube linestage isn't going to be greatly improved by slapping in a Teflon capacitor.  The circuit itself needs to be corrected, or an alternative and improved preamplifier needs to be purchased.

Flash in the Pan:
The high-end audio scene is filled with hyped products and broken dreams.  I could name company after company that have failed since the 1980s, and some of them even produced well-reviewed winners that should have seen these start ups to the road to success.  However, the audiophile market is a niche one and it's apparently quite easy to fail.  Unless you are handy with a soldering iron, my advice when purchasing equipment is to buy from established brands that have been around for awhile.  This will lead to easier service, possible product updates, and better resale value.  Some of the classic brands: Audio Research, Conrad-Johnson, Mark Levinson, KEF, Quad, etc have a long track record and the quality of their gear, plus the resale value shows this.

Vintage Madness:
I love old tube gear and vintage speakers.   However, in the world of amplifiers, only a few of the old designs really stand the test of time.  These were usually the expensive pieces back then  - Marantz, Fishers, the top-level Eicos, Fishers, Dynacos, Grommes, Fairchilds, etc.  On the other hand, the more budget integrated and console amplifiers suffer from poorer circuits, cheaper parts, and output iron with less bandwidth and smaller cores.  The same holds true with speakers - only some have really held up to the test of time, while the majority of the vintage units sound rolled-off and not very detailed.  Sure, these old-timey pieces can sound enjoyable, but they ain't hi-fi.

Separated at Birth:
If you're a simple kind of audiophile who wants the minimal moving parts, then by all means go the integrated or receiver route.  Just keep in mind that this path will minimize - unless in/out RCA jacks are included - your upgrade possibilities.  Personally I prefer separates - preamplifier and amplifiers - which allows different combinations of gear to be tried.  Difficult speakers to drive?  A tube preamplifier and a hefty solid-state amplifier might just be the perfect combination.

Budget Talks:
Even if you are silly rich, every stereo system is built around a budget.  Things to consider: how much are you willing to pay and how will it match with the rest of your system?  I could, with enough bad decisions, put together a fantastically expensive system of Stereophile Class A components that would make any listener run out of the room screaming,  For example, couple a low powered singled-ended amplifier with an inefficient speaker with a low 1-ohm impedance curve.  Though painful, it's best to start with a good front-end, and then buy and sell up the chain, keeping in mind that a manufacturer's lowest priced product is not always the best place to start.  For example it will be better to save to buy a Rega P3 than the entry-level P1.

David and Goliath:
There are giant-killers out there - budget gear that punches above its low price and gives a great listening experience.  KEF and Wharfedale speakers easily come to mind, along with some of the cheaper Chinese tube amplifiers.  However, no matter what you tell yourself, they still are budget pieces that can be surpassed with something more expensive.  It's just a matter of how much you are willing to spend and if you ears really demand that much perfection.  I think it's important not to lie to yourself and accept the limitation of your system, which brings me to my final point.

Times are A-Changing:
When buying gear and bring in a new component into the system, it's all too easy to get swept away thinking that the latest change is always for the better.  It's also far too easy to think an expensive unit will always surpass a cheaper piece.  It would also be wrong to think that newer is always better than older.  Again, system matching and careful listening is required here.  It's also good to have a few audiophile friends over who don't have an emotional investment in your stereo.  If they have experienced ears - and are of an honest nature - they can also tell you what faults they are hearing, instead of just concentrating on the best parts of upgrade.

As always, comments and suggestions are welcome.

New Project: a SE 6CB5A amplifier

After the completion of my 1625 "Command" amplifier, I began to cast my eye around for another project.  This time I wanted to yet again tackle a triode amplifier, perhaps doing a push-pull 2A3/6B4G type.  However, the pesky cheapskate that lives inside my head just couldn't spend that sort of coin on a set of output tubes.  While searching around, I read a thread on diyaudio that lead me to this blog post on Vinylsavor.  Check it out for the signal schematic.

The 6CB5A is a 1950s television sweep tube that wasn't designed specifically for audio, but the curve traces in triode mode are quite good.  This cheap tube can also produce 6-8Ws in single-ended, which is pretty close to the mojo of a 300B.  I also liked the idea of using the 6N7 driver, thought I opted to not implement the expensive interstage transformer, and instead went with RC-coupling.  Hey, this is a budget build after all.

Output and power iron will be from Edcor - I really liked the quality of sound I got from them in the 1625 amplifier.  Chokes will be from Triad and the rest of the parts will be standard bog stuff you can get from Mouser, Allied, and Digikey.  I've also opted for some current meters to monitor the health of the output tubes.

Since a single 6CB5A takes a mighty 2.5A @ 6.3V to light up, I had to purchase a separate filament transformer to power the 6N7 tubes.  Other than that, this is a pretty standard power supply with a fake dual-mono separation for the two channels.

Output iron has been ordered.  Everything but the top plate metalwork has already arrived, so I will provide another post when all the parts have come in and everything has been wired together.  I'm quite curious to hear what this amplifier sounds like since the build/design approach is much different than the 1625 amplifier.  The 6CB5A amplifier will have no negative feedback, a pure triode amplification chain, and minimal parts.  In my experience this should lead to a big sound with a slightly underdamped bass.  Stay tuned to find out!