[jrebman]

Kevin,

I dare say that this just may be the most fun I've had with audio in a long while.  It runs a close second to being out in the woodshop or sitting at the bench, but ultimately, the music is where it's at.

I'm still planning on a weekend getaway -- assuming Linda's foot doesn't hurt too much to drive.  The Doc told her yesterday that we really have to start thinking very seriously about a car with an automatic transmission because her left foot can't take clutching for much longer.  We hadn't planned on getting a new car for a long time, so throw one more large unexpected expense into the works .

-- Jim

[Len_Dreyer]

Jim,

For what its worth, early this month at my brother's request, I tested my Carina with my Tyler Acoustic Taylos (89db, two way speakers) and they played amazingly well together. I've had my Carina for about 10 months.

Also, in September, my brother brought his Carina down to our NJ beach rental and we swapped out input tubes, each day for four days, using his NOS collection. At that point, I had no NOS tubes in my collection.  I listened blind and when I was done, I chose the Bugle Boy 6DJ8 as my favorite followed by a Siemens 6922. He said they were his favorites too. He had an RCA/Mullard rectifier and I think Mullards were the power tubes. Needless to say, I now have seven Bugles Boys 6DJ8s at home.

[chrisby]

 Chris, as Bud is making your iron, be sure to have the primary wound for 3.5K. I also like the flexbility of an 8- and 16-ohm secondary (the D5nf is a 16-ohm driver). I've done a ton of testing with over 30 2A3 tubes (all NOS) and I tend to get 4-watts minimum... the better ones 4.5-watts and very low distortion, generally less than 0.5% at 1-watt.

 I think you're retrofitting a pair of existing amps, right??

 Regards, KM

thas rite - sorry, Paul ,  the format is designed for major mods, while the Wright Mono7's far less so.

[jrebman]

Another update...

Toolk a chance on a new amp.  I knew I was going to get another amp sooner or later, but was undecided between a number of options.  I decided to take a chance on a PP amp that seemed to me to be somewhat different from your typical PP amp.  This one uses EL34, KT-77, KT-88 and 6550 types runs full class a1, and has no NFB, is a true dual mono design and uses a 0D3 voltage regulator tube on the poer tube grids for linearization, and is tube rectified.

So, what is it?

It's the Decware Zen Torii II, and it is leaps and bounds ahead of every other amp I've tried on the F120As -- slam as one would expect from a PP amp, but airy highs, very nice tonal balance across the range, detail, excellent tone and prat, and extremely good soundstage and localization.

It is like the best of everything else I've tried, with an extra bit of something that I can't quite describe.  Well, how about total effortlessness?  It makes these 88/89 dB speakers sound more like 98/99 dB speakers in their ability to react to transients and recover without the slightest hint of overhang.  It's a keeper.

Right now it's running with JJ KT-88s, some NOS RCA 0D3s, some cheap Ruby 5u4g rectifiers, and some new production 6n1ps for drivers.  I can only imagine what a bit of tube rolling will bring.  Source is the still breaking in RWA Isabellina (soon to go in for the full upgrade to Isabella and headphone amp.)

What a beautiful amp this is -- like no PP I've ever heard, and like the best of SET with all the slam you could want.

And the fact that I got it used for half or more off the price of the other amps I was looking at, makes me just that much more delighted in the choice.

Back to the music...


-- Jim

[floobydust]

 Hi Jim,

 Congrats on finding a good match with the F120A Fonkens... 25 watts is certainly enough to twist 'em around a bit. The Decware also sports a very low damping factor, less than 3, so (like a zero-feedback SET) does not provide a high degree of braking on the driver. Let us know how this setup fares in the long term.

 Regards, KM

[JLM]

Like floobydust said.  I tried the original Decware Torii with my F200A based MLTL's.  As you stated Jim, lots of good came from the pairing, but the bass was exagerated and very loose.  OTOH my speakers are room rated flat below 30 Hz, so may not be a problem for you.

[jrebman]

The low damping factor was a concern, but somehow, between the alnico driver, and the aperiodic cabinet, it just works.  Bass is more articulate than with even the RWA 30.2, which sounded a bit overdamped to me at times, and was something I thought might be the case even before the speakers had arrived.

The room boom is no worse than with the Carina, so next big project is to get the room treatments going.

Also, the JJ KT-88s do a strange thing with the lowest frequencies in that it pinches them off a bit, giving the impression of better control -- at least that how some other Torii II owners describe it.  There are rectifiers, power tubes, and driver tubes to roll though, plus the high frequency adjustment to tailor the sound, but I'm going to wait until I have the active gain stage in the system before doing too much of that.

There is always room for improvement, but at this point I'm happy that the amp/speaker synergy just seems to be there.

The switch from silver to copper speaker cables also made a big difference, and copper is the clear winner here, so again, as so many other owners of this amp have said, cabling really makes a difference.

Next tweak is to put the amp on a trio of HRS Nimbuses.

-- Jim

[nature boy]

Right now it's running with JJ KT-88s, some NOS RCA 0D3s, some cheap Ruby 5u4g rectifiers, and some new production 6n1ps for drivers.  I can only imagine what a bit of tube rolling will bring.  Source is the still breaking in RWA Isabellina (soon to go in for the full upgrade to Isabella and headphone amp.)

Jim,

I have a Decware Zen SE84CS EX Mod amplifier that is paired with a pair of Hornshoppe horns.  The amps voicing is easily changed by tube swapping, particularly the rectifier tube.  The Ruby 5u4g rectifier tube is nice, but I encourage you to listen to a RCA 5u4g tube in it's place.  Much more musical and cleaner presentation IMHO.  Just some food for thought.

Enjoy your new Decware Zen Torii II, Steve Deckert makes a very nice amplifiers as does Eddie Vaughn with his Carina.  You also don't have to take a 2nd mortgage out to buy one either.

NB

[jrebman]

NB,

I've been thinking of just that -- the RCA 5u4s -- a buddy of mine has a fairly large stash of them and I'm sure he'll let me borrow a pair for a little while.  I also have a nice pair of Mullard/Blackburn GZ34s, which will also get a try.

When I originally encountered this amp back last Spring, I really didn't give it a second look.  I just assumed that it was a compromise that was offered for the existing Zen amp customers who wanted more juice, and that it would basically be just another ho-hum  PP EL34 amp, and I've had one of those in the past, well, actually 2.  They were decent amps, but not what I was really looking for.

Thanks for the tip.  How's the little guy with the Horns?

-- Jim

[nature boy]

Thanks for the tip.  How's the little guy with the Horns?

Jim,

One of the best amp - speaker combination's I have ever heard in my small dedicated listening room.  The SE84CS Ex Mod and a Fostex 126E in Ed's corner loaded design is very special pairing.  Keeps me happy.

NB

[planet10]

The low damping factor was a concern, but somehow, between the alnico driver, and the aperiodic cabinet, it just works. 

Fonkens tend to like anm ps with higher output imprdance...

dave

[floobydust]

The low damping factor was a concern, but somehow, between the alnico driver, and the aperiodic cabinet, it just works.  snip...

-- Jim

 Actually, I was not suggesting a high damping factor for the F120A, I don't think the F120A needs a high DF, better without it as the combination of the driver's suspension, motor and enclosure all contribute to well damped cone movement.

The low DF may (partially) explain why it (Tori II) has some characteristic sound of a SET amp, along with the lack of feedback. There is still one specific difference however, the push-pull design still "flips" the magnetic direction of the OPT core when it crosses between a negative and positive signal level. Keeping the output stage in class A mode does eliminate the effect of one device going into cutoff however, but that's not the same thing.

 I would be interested to hear your impressions after doing some listening with the T2 and then go back to the Carina.

 As for tube rolling.... (okay, my opinion comes out here), I'm not a big fan of it (unless it's just different brands of the same type). I would caution swapping the GZ34 for the 5U4... it will result in a higher B+ voltage. As the GZ34 has an indirectly heated cathode, there are some options on how the (5U4) rectifier may be wired.... so probably worth checking before you swap it. Swapping output (tubes) between different types can also result in different bias points (and operating curves), so unless you can adjust the operating point, it's not a faithful comparison. The same applies to input/driver tubes... just my $0.02.

 Regards, KM

[jrebman]

Kevin,

Understood.  The tube rolling was more intended to explore different voicing possibilities, as each tube will react differently to the operating points set by the rectifiers and the characteristics of the drivers at the existing set operating point.

I'm most interested in seeing what flavor best complements the fonkens as right now I don't really have any particular allegiance to any of the compatible tube types, and only a slight prejudice against the 6n1p, which has not really floated my boat in the past, but... different amp, different speakers, different everything now.

I've got some noticeable, but nothing like annoying, hum on both channels -- barely noticeable on the right, and more pronounced on the left, so I'm suspecting the driver tubes right now.  Hum is constant regardless of volume pot setting.

-- Jim

[chrisby]

congrats, Jim - it sounds like the 'steens are finally able to show you what they're made of

[floobydust]

congrats, Jim - it sounds like the 'steens are finally able to show you what they're made of

 Hmmmm.... wood, glue, wool, funny dots, felt... oh, and a F120A.... and some wire.

 Yes, some extra power never hurts... unless you push them too hard. I would urge a bit of caution.... with a 10-watt rating he probably has enough power to damage the little guys, and that would truly be a shame.

 Back to tube rolling..... okay, more bias from me..... In my humble view, the term voicing is a nice way to say we're purposely inducing some non linearity, hence no longer an accurate reproduction of the original signal. What else could it possibly be?? The less signature any amplifying device adds to the original signal, the more accurate, or faithful, it will be. This might not always be sonically acceptable with other pieces of gear which may interact poorly together, but IMO, you should fix the weakest link in the chain, not modify the rest of the chain to compensate. For basic tube rolling, you can pick an operating point and a set of voltages/current which will work with multiple (similar) tubes, but you won't get optimal performance and linearity from the resultant circuit. Okay.... I'll step off the soapbox now... to each his/her own.

 I am happy that Jim has found a combination of gear that is more acceptable for his listening... but again, I still want to hear an update a few weeks down the road as things settle in.

 Regards, KM

[jrebman]

Kevin,

Yes, I too want to hear what happens a few weeks down the road .  The amp was designed and voiced for the el34, so I'll try some of those to see what happens.

BTW, the power rating for the F120A., according to the madisound site is 30 watts, not 10.

Just got done listening to a CD of classical and flamenco guitar and smiled through the whole thing.

There are still some upgrades and changes to the system as a whole, to come, so it could be a while yet before everything learns to play nicely together.

Kevin, yes, it doesn't have quite the  free-floating, holographic presentation of a SET, but it has a lot more of it than any other PP amp I've had.  Plus, I'd be hard pressed to find a single tube SET that can deliver the slam that this does, at least at anything near what I could affor, and the transmitter tube SETs run too hot for this little room.

-- Jim

[floobydust]

 Hi Jim,

 I'll be interested to hear (pun intended) how things progress over the next few weeks. I looked at the Decware site... some interesting design concepts for the T2. It did get me thinking... maybe find a way to use a pair of 6B4G DHTs in the amp... should be good for 10-15 watts. I recall a design in the ARRL handbook from the late 50's that used a pair of these in push-pull for a small modulator amp.

 Re the F120A rating... depends on how you read it, the PDF spec sheet from Fostex shows two ratings, 10 watts, but also gives a "music power" rating of 30 watts. The label on the driver also shows: NOM 10W, MUS 30W. So I guess mileage varies somehow.

 Regards, KM

[chrisby]

congrats, Jim - it sounds like the 'steens are finally able to show you what they're made of

snip...
 Hmmmm.... wood, glue, wool, funny dots, felt... oh, and a F120A.... and some wire.
 Regards, KM

well, I was thinking there was a little bit of craft, magik and luv involved as well (but then I guess that's to be expected  )

[floobydust]

 Chris.... I'll go with the craft and some luv... I'm a little too old to believe in magik! In any case, very nice work... you earned it.

 Regards, KM

[chrisby]

Chris.... I'll go with the craft and some luv... I'm a little too old to believe in magik! In any case, very nice work... you earned it.

 Regards, KM

I'd be inclined to agree with you on the magik too, if it wasn't for looking in the mirror every morning and wondering why my wife of 35 yrs still lets me share her life.