Ultrapath for Moondogs

[leok]

I've installed the "Ultrapath"mod that Erik suggested. It's very impressive. If you can believe it, detail takes another step up. Ambience is more evident. Strings are cleaner. I have some burn-in and tweaks still pending, but this is a very promising approach that I'll probably keep.

My only planned addition is to keep the original C4 where it is and add Erik's mod (45uF from the hum balance pot wiper to B+ at the power transformer). The reason is to keep the 2A3 cathode ckt. referenced directly to gnd. I'll know tomorrow if adding the original C4 back in makes a difference.

leok

[Deang]

SET amps are for people who understand the mysteries of the electrical universe.

As for me, I will be content if I can once again move the universe with some air.

I simply could not deal with the restricted nature of the dynamics at the levels I prefer to listen too. My musical tastes require unbridled dynamics, and the wondeful transparency of SET would only take me so far.

I'm very happy however that this is working out for you!

[Audio Flynn]

Dean,

You bone crushing headbanger you!

I am done with assessing the strong points of your character.

Hope the family is well.

Rick

[Erik Mandaville]

Dean:

With all respect, I must beg to differ. I have done nothing but scratch at the "electrical mysteries of the universe," and enjoy single-ended amplifiers for the very characteristic with which you seem less comfortable. Into La Scalas or Lowthers, the otherwise very modest output of a 2A3 can be painfully loud. But who wants that kind of potentially dangerous volume? I certainly don't. It is the directness and almost uncanny sense of realism and immediacy that fascinates and captivates me. Like colors in a painting, dynamic contrasts are, for me, one of the elements of music that give it life, breath, and substance. No system I have ever owned has been able to recreate the emotion and impact of live music better than the Moondogs and extremely efficient horn speakers. I have built several pair of loudspeakers using some of the best drivers and passive crossover components available, and they just don't have the magical qualities of the La Scalas or horn-loaded Lowthers. And that, I think, is the significant and in my opinion absolutely correct aspect of your statement: Low-power amplifiers (3 watts or less)must be used with speakers of extraordinary efficiency and sensitivity in order to produce a believable illusion of live music. Crossoverless Lowthers have truly amazing speed and transparency, but lack just a bit of the foundation needed for truly comprehensive reproduction. The La Scalas, on the other hand, handle lower octaves far better -- but may or may not (I can't make up my mind!)have the midrange articulation of Lowthers. Poor me, right!? So this is the reason I'm working on a system that combines the best qualities of both. The search is of course part of the fun, but the appreciation of music is ultimately what matters most to me. Moondogs and horns have just brought me closer to the essence of live, present music than anything I have heard!

Erik

[Deang]

"...the otherwise very modest output of a 2A3 can be painfully loud."

What output? It's 3 watts. The pain comes once you get them out their power band and you're listening to 20% or more of harmonic distortion. Dynamics roll up like a scroll, and the treble sounds like it's being etched into concrete. SET amps are like any other amp. When the power is gone -- it's gone. I do believe SET amps probably sound the best -- as long as you don't drive them out of their power band.

As everyone here knows, I've owned quite a few amps over the last two years, and I never ONCE experienced this with any of them.

Also, keep in mind that both the RF-7's and Cornwalls come in around 98-99 db/w.

[mobile homeless]

Perhaps this last assessment misses the mark a bit, Dean. Actually, that is the SET amps STRONG suit as it exhibits the most sublime clipping characteristics of any amplifier, although most tube amps are far better with clipping compared to solid state. While the SET amp might run out of steam at a certain point, the treble RARELY hardens and becomes overbearing, despite your claims.

Erik's point is entirely correct in that one really does need an appropriate speaker with a benign load that does not dip too low not to mention high efficiency in the 100dB and above area. Combine these two aspects with a very well matched front end, including an excellent source and a preamp that does not do damage (very hard to find, sadly enough), and even a 3.5w SET can bring amazing dynamics, especially in the micro area.

I still don't think you have heard a good SET amp, despite the flirtation with the Apollos. This design was more on the high power side of the SET equation, something that just doesn't offer the magic of the low watt brethren. To this day, I have not heard a high power SET amp offer the same experience as the low power choices.

On the other hand, if you are looking to rock out with Journey, a band that was never recorded well or without massive use of studio production, looking to shake the rafters, it would probably be safe to say SET amplification in general is not for you. Yet, I play a host of rock bands (I have more rock and indie recordings than Jazz in actuality) and all on the 2A3 Moondogs and Cornwalls. As a drummer in bands for over 25 years, I appreciate dynamics as well. I also appreciate great "JUMP" factor, something the SET amps can do like no other. As I stated elsewhere, I have been rocking to some great vinyl the last few days. Early mono Beatles recordings played at VERY high levels have been amazingly open and alive sounding, with no compression and a sense of tactile realness that surpasses most of the PP amps, although I have loved a few vintage for different reasons.

So be careful of assumptions here. Ironically enough, it is in the midrange and treble that I think the SET amps just plain runs over almost all other amps, even a very high levels if matched with the right speaker. And the 2A3 actually has an amazing low end, that betters the 300B in tautness and tone. As of now, the very bottom of my 2A3 Moondogs betters any amp I have on hand (although the EICO has a more full lower midrange).

kh

[NOSValves]

I for one really wonder what the 3 watt rating really relates too ? Is it 3 watts continuous with much higher peaks ? If so what are they capable of peaking at ? If they hit a brick wall at 3 watts I just don't see how I could ever live with them ! I have tested the Wattage output needs for my taste and the absolute least I can deal with is 10 watt peaks and that with some music still can leave me wanting more. Mind you this is with Lascalas. When using my 299B as it sits right now strapped in triode it is about 10 watts peak output when playing at about a 3 watts in the relax or laid back area's of a given song. When the heavy transients hit it peaks a 10 watts. I find this barely fills the bill and leaves me wanting just a little more !

I think the thing that most of the 3 watt camp needs to understand is that some of us don't have ears that have been treated with kid gloves are entire life and we may need more volume to get the same level of detail and involvement out of are music. Just like all other aspects of this hobby its all subjective what's good for one is not good for all. I have many customers that never push there amps as high as I do when I have them here. There ears are more sensitive then mine. Does it mean I can't hear what's going on with the music I think not ! It just takes a little more volume for me to hear and enjoy it. I have continually used my 15 year old daughter as a test to confirm what I hear is indeed what she hears and it always comes out the same I do !!

Craig

[leok]

My ears are 55 years old, like the rest of me, and I do have to handle them with kid gloves. Seated 20' from a string quartet + piano, I found the volumes, on the fortes to be all I could tolerate. On the other hand, I've had no trouble hearing a single baroque guitar, when I was seated halfway back in a large, church. Also, seated in the first row, balcony, in most concert halls, i find the amplitudes comfortably betwen the previous two extremes.

When I listen to music, I try to match the amplitudes I would experience in the settings chosen by the recording engineer. That way I'm hearing the instrument(s) at their intended (by instrument designer and musician) amplitudes.

I do know that others can tolerate, and enjoy louder sounds than I can. A live, unamplified drum kit can drive me from the room.

In this context, The Moondogs have plenty of power and the RF-7s are certainly in a sweet spot. Although I understand that that sweet spot can extend much louder. I think if I wanted much more acoustic power, more watts would be in order. I've measured 4w peaks (not rms) feeding (come to think of it, that was the Forte-IIs) the Forte-IIs. The peaks were on snare rim shots on a James Taylor song.

What I really wanted to mention is that I added the original C4 back into the Moondogs. The combination of the added "Ultrapath" cap and original C4 is, for me, by far, the best solution. Strings are fabulous now. Detail and ambience better than ever. Tomorrow I'll change to the RCAs for a real treat.

One point concerning the RF-7s, is that their performance, when treated with a good signal, is quite remarkable. Maybe their worst sin is that, as originally voiced, when subjected to less than clean electronics they produce a crisp, hi-fi sound. With a little voicing tweak and some good electronics they're very impressive and natural sounding.

some theory:

I believe the original C4 carries 2A3 grid currents and the "Ultrapath" cap carries 2A3 output currents. This way The output electrolytic, C3, is out of the AC output current loop, C4 is not subjected to high output current and resulting esr affects that would distort 2A3 grid/cathode voltages. (an added inductor between C3 and the "Ultrapath" cap might further isolate output currents from C4, but i'm not in a real hurry for improvement)

Thanks to Erik for the Moondog "Ultrapath" mod.

leok

[Erik Mandaville]

These are excellent posts!

And to Leo and the ultrapath output connection: With C4 back in the cathode resistor bypass position, what value are you using for C4A? Your idea of providing an improved ground reference for C4 makes sense, and I am very curious to add C4A between cathode and the OPT. I can't remember what value you said you used for it, Leo. Was it the same as the stock C4, or a little higher -- 50 or 60 mfd. maybe?

Great work!

Erik

[leok]

Erik,

I found a Solen film/foil polyprop. 50uF 400V at Madisound. Price was reasonable (I'm glad a Jensen wouldn't fit). As it is the Solen just fits between C4 and the 6SN7 heater rectifier wireball. There's a terminal srip, most of which is unused, that will have to be truncated so the new cap sits low enough that I can get the bottom covers attached.

The Ultrapath cap makes the output circuit so much tighter .. no looping through ground and the B+ supply. Really nice upgrade to an already great amp.

leok

[Triode Pete]

Jack Elliano's Ultrapath circuit certainly is interSETing! Are you using a regulated power supply? That would be the ultimate tweak!

As far as SET dynamics goes, my current SET (low powered 2A3 - a whopping 3.5 watts!) dynamics blows away my old McIntosh SS amp, my Fisher 500C receiver and countless other amps I've tried with my K-horns. Certainly sounds illogical but I can't explain it! Possibly it's the fairly high gain pre-amp that I use. My push-pull 2A3 has more slam & authority in the bass, but it's less accurate & after close listening, it's a bit bloaty & flabby! The tonality with the 2A3 SET rules!

Had numerous audio buddies over to listen in the past & they cannot believe the dynamics & tone from a 2A3 SET! I played Patricia Barber's tune, "Company" (CD version from "Modern Cool"). The drum kit, bass & trumpet puts you "realistically there", very loud (can't communicate without shouting) and the pre-amp volume controls are at 11 o'clock, approaching 12 o'clock. The SET amps aren't even running out of gas! This is much louder than I normally listen to!

Many of the audiophools in my club have huge egos & when they say my system sounded better than anything they heard at the Home Entertainment Show (Stereophile Show in NYC), I take it as a great compliment! But I believe you really need super efficient speakers that can go low (like K-horns). Not to bash LaScala's or Belle's, but I think you need more power to reinforce the bass on these speakers since the bass is an octave higher than K-horns. I have not experienced this with Cornwalls, however, although my brother-in-law prefers 2A3 push-pull amps vs. 2A3 SETs on his Cornwall system. As everything, I guess it's a matter of taste. Isn't audio fun?

Enough rambling; Audios,

Pete

[leok]

Triode Pete,

No regualtion on the PS. The logic behind using one is not lost on me, but I haven't any idea how to make one that wouldn't insert more regulation noise than the unregulated problems it removes. So far I've just resorted to big caps or cap farms. Not a lack of interest, just lack of capability.

I continue to enjoy pp amps (now on the Forte-IIs). In a note, Erik mentioned the Sovtek 6A3 and the KT66s in my amps all began saying "we're linear, don't replace us." A little Ultrapath work there and 6A3s all around might give the Moondogs a run. And, if I do want to blast .. the pp is available.

leok

[Cut-Throat]

Deang

----------------

SET amps are for people who understand the mysteries of the electrical universe.

As for me, I will be content if I can once again move the universe with some air. I simply could not deal with the restricted nature of the dynamics at the levels I prefer to listen too. My musical tastes require unbridled dynamics, and the wondeful transparency of SET would only take me so far.

---------------

With as often as you change gear, maybe it's time you slowed down a bit and give Audio by Van Alstine a try. You may think the equipment is ugly, but after you have been in this hobby for a while, you tend to use your ears instead of your eyes.

If dynamics are what you strive for, Maybe 250 wpc. with a tube driver stage is what you are craving. I own SS, Push-Pull, SET and Hybrid. - and AVA Hybrid is the Best! I have been an AVA Customer for 17 years. I doubt you have owned an amp for more than 17 days!

Do you think?

[NOSValves]

Cut ,

You sound like a commercial dude !! Dude your getting a AVA !

Craig

[mobile homeless]

And AVA Hybrid is The Best!

The Best is the new AVA 2 Channel Mantra! Stock is going up...This has been your coming out party!

kh

[Cut-Throat]

Geez kh,

Did anyone count the number of times you recommended the moondogs? Or maybe your friend Jean-Francois, that you're always pimping. So how is my recomendation different than yourself?

So my coming out party is spoiling your forum? You get a little touchy when someone recommends a product different than yourself?

Does this mean your Stock is going down?

I thought you were bigger than this? Or which rule on your forum did I break?

[Randy Bey]

There are many rooms in my Father's house, and many roads lead to it.

Kelly's humor is a bit... dry... sometimes. I sincerely doubt that he is doing much more than pulling your leg.

As far as SET and dynamics go, I found that my 8 watt tubes were a bit louder than my 25 watt SS NAD receiver. And as mentioned before, clipping is far more benevolent than with SS. I do manage volumes that get my ceiling tiles shaking and dust drifting down; the Romex house wiring starts vibrating against the inside of the walls; but I guess other people like it LOUD. It's early and I don't have a head for numbers before about 12AM but the geometric progression of speaker volume v. amplifier power makes the difference between 8 watts and 800 watts not all that much.

But whatever floats your boat. The fewer freeks into SET, the more tubes there are for the rest of us.

[NOSValves]

Its different to give a recomendation when someone asks then to bring your favorite stuff up on every occasion ! This thread is about moondogs and mods to them not about how great AVA products are !

Craig

[Cut-Throat]

"Its different to give a recomendation when someone asks then to bring your favorite stuff up on every occasion ! "

NOS440,

Well, I have made a grand total of 3 posts in all of the Klipsch Forums Recommending this Line of gear, since I have been posting. If this is over the top for you, I'd guess you are in the audio business. I am not. I have nothing to gain.

Explain to me how 3 posts of recommendation (When no-one asked) is "on every Occasion" - This sounds over the top!

[Erik Mandaville]

Morning Cut-Throat:

Just wanted to mention I recently visited the AVA website, which is well done. I honestly really like the way their products look, in that they sort of reflect a certain historical, 'receiving radio' lineage. I've got a couple of old receivers (Hammarlund) that I like to listen to shorwave on, and the AVA stuff reminded me of that -- granted the Hammarlund is about 5 times the size!

However, the main reason I'm writing here has to do with Kelly's post. I honestly don't think he was intending anything unkind or antagonistic. It was more of a sort of tongue-in-cheek sort of thing, I think. He spent some time describing merits of the Pantheon, as I have also done with my own Moondogs, Bottlehead Foreplay preamp, and a few products by other small audio electronics companies. So It's understandable that you should or would want to share something about the AVA equipment. I was familiar with their Dynaco Stereo 70 upgrade kit, but didn't know they also had quite a range of SS, tube and hybrid amps and preamps. They seem reasonably priced, too.

You know, we often go to lengths describing the sound of different components, but I am starting to really believe that the receiving apparatus (apparati?)-- namely our ears and associated sound processing structures -- is as equally or even more important. In otherwords, the differences in individual physiology and perception must have some influence in all of this. And heck! With all the different choices available, how can anyone audition everything in order to find the very best, much less afford whatever 'the best' happened to be?! So this is another reason I like the simplicity of single ended, point-to-point wired amplifiers: They are much easier to 'season-to-tast,' if you will. An oil cap in position; a poly or ceramic cap in another...carbon comp. resistors instead of metal film, etc. etc. This is my point. We all have different tastes and likes. I joke with my wife about how much salt she puts on her food, and some have kidded me about my heavy use of bright-sounding capacitors and interconnects.

Thanks for sharing that AVA stuff -- they look really pretty good, and seem to use high quality toroidal transformers and other parts. I also noticed they use ceramic bypass caps across the AC input jack. That is absolutely a trick that was also used many years ago to help snub and filter line transients and RF grunge. Cool!

Erik