erik2A3

All very good points regarding directly driving an amp like the Dyna from a source with volume control. I've done that here with our squeezebox Touch, and there is quite.honestly not much I would change. As Rongon mentions, no other circuitry to get in the way. As also explained, the input sensitivty and high impedances of these great old amps are very sympathetic loads for present digital sources, and don't really need voltage gain of line amplifiers -- unless of course one happens to like what the insertion of a line stage, tube or ss, does for the end result. All up for grabs in that respect.

I agree with the vintage options mentioned above. I gave my dad a pair of Heresies and Dynaco ST70, and the two work virtually ideally well, and can play loud and clean (if that's what's wanted) without distortion. Not that an integrated wouldn't be as good (a subjectively determined thing), and an integrated does not need a separate preamp. In addition to the Dyna 70 that I found to be such a great match for Heresy IIs, was an amplifier from a company on the east coast called Sophia Electric. Some of their products are expensive, but my wife bought me a Sophia Electric 'Baby' as a Christmas present a few years ago, because she thought it was 'cute.' It is a neat (and very heavy for it's size) little amplifier, but its sound quality reaches well beyond what one might expect from an amp of such diminutive proportions. Honestly, it's an extremely good amp for its type, and was a good match for every Klipsch speaker with which I tried it -- Heresy Is and IIs, La Scalas, and Klipschorns. One Caveat: output tubes seem to be only available from the company. I bought several quads to have on hand, though the driver stage amplifier is common. Vintage, as Mark and Craig expressed, is always cool. The Dyna 70 I had took a bit to quiet down, but I figured out a completely new grounding scheme that worked so well I thought I had forgotten to connect the speakers. It was that quiet compared to the stock setup. The input impedance of the Dyna 70 is quite high at around .5 meg ohms, and can work with a passive attenuator in front of it.

It's possible to make (or in some cases buy) a stand alone (or along side?) switch box that has the number of inputs you want suitable for the number of positions of the switch you're using on one side, and a single pair of outputs on the other. These would be connected to just one of the existing inputs on your preamp. Switching takes place on the swtchbox, not the preamp. A make before break switch works best for something like this. Erik

Craig: I was just explaining that I knew they were metalized when I got 'em. I know you weren't telling me to change anything, just explaining your take on things, and that you know I know enough in terms of messing around with salt and pepper and spice effects of seasoning with different cap types, and that I'll use what I want despite the prevailing audiophile reputations of whatever cap, resistor, OPT, or hook-up wire type that might be under consideration. I'm stubborn like that, and in most cases it will be the less expensive part that gets the tap. That said, I won't reveal what I spent last year on OPTs for those 300b amps. I can't help but admit that they are really, really good though. Fifteen to twenty years ago, capacitor crazy was in high gear with me, as was the ludicrous number of DIY interconnect and speaker cable experiments. I loved the cables I once made from the power cords I found on a couple of discarded garbage disposals! ;o. Then there was the Romex, twisted pair shielded coax, thermostat, ethernet, low voltage sprinkler (actually very good and cheap!!) etc., etc., etc. All is good. Stay cool; it's sweltering-humid down here like it is in so many places. And thanks again for the reminder about those caps from AES. Seems every time I order from that place, I submit the order and then six hours later remember two other things I needed even more than what I had ordered the first time. Lousy planning! Erik

I know the Audience caps are metalized, and I was not comfortable with the cost/performance aspect. I've used far less expensive metalized types of more humble lineage that sounded good from the very start and stayed that way. These amps have just a single cap in series with the grid of the 300B, so it would be nothing (other than mildly boring) to snip the things out and experiment. Just spent too much time on that sort of thing in the past, and what's in there now sounds good.

Craig: I have seen those caps at AES. They are neat looking, too. Price is good. I've been considering Multicap, which I've looked at for years and always liked in terms of design philosophy, lower resulting ESR values, stuff like that. This was for coupling in amps, but might be interesting for crossover use.....just kind pricey right now. I've got some Auricaps in 1uf, though, and could parallel those. I tried .1 Auricaps in my 300B amps, and took them out after a couple of days. Just didn't like it.....too strident, and to me kind of course sounding. Maybe after they had broken in, but I just still haven't wrapped my head around caps and wire breaking in. Just slow on the uptake on that I guess. Really good construction on those things, just not right in terms of tonal quality to me. Actually, I've been using some really well-made (IMO) Russian PIO types for a few years that I really, really like, and got a bunch for lots less than the usual, more common sources. That's what I replaced the Audience caps with. Not saying they're bad, just a matter of finding the flavor and voice I was looking for in a pair of 300B monoblocks I did last year. Thanks for the reminder about those MKP caps at tubesandmore, I had forgotten about them. Erik

Hi, Craig I'm doing good, thanks -- I hope you are too. I think you're really right about the preference issue. The OTLs really aren't for everyone, but as you suggested, neither is anything else. The higher power T16 (still flea watt by many standards) has been tons better suited to the La Scalas in a larger listening space. They are the Industrial, fiberglass-covered, clad in aluminum armor variety, and are pretty cool-looking (to me) in an otherwise pretty tame-looking interior. They came with the infamous AL network (which I at times in the past liked in some cases and not others -- mostly didn't care for) that sound pretty decent with my vintage 100 watt/channel SS Hafler. With SET 2A3s and the the Transcendent SEOTL, that AL network sounded honestly really horrible. What's nice about these La Scalas is that they are very easy to bi-amp, and I've got the networks outside so I can try a couple of different things out. So, I cobbled together an instant type A with what I had on hand: please don't tell anyone that for right now I have an 10uf NP electrolytic paralleled with a 3uf film for the input to the autoformer. Even with the NP electrolytic, the sounded opened up in a huge way with these little SET amps. I've made the decision to go ahead and splurge on some really fancy caps -- SOLENS! (wink) in the near future. I'm building a T16 right now and want to get that out of the way first. Erik

Seti: Very interesting horn! what is that cabinet in the background without the driver? A single, full-range 'something or other'? Appears that the mouth of the horn is just below...just curious about it.

Sure! Have fun with the Dynaco! Erik

Hi, Bruce I love my Moondogs. It's good you got the manual from Ron; he's never been anything but helpful to me. Moondogs are in use with the K-horns in our combined HT/music system upstairs. I've made some modifications to the seotl amp in order to use it with my Grado phones. I had been using the Moth amp for headphones, but the 1.5 watt OTL is better in every way. Erik

And I should add (Erik Mandaville here, by the way -- I had some trouble logging on, and just tried this other handle quickly, and it took. Seems the system has changed a bit....). that the SEOTL because of its lower output power is (probably) better suited to more simple crossover types as in 6dB-12dB/octave designs. With these lower order slopes, there isn't the same level of insertion loss as steeper designs, and with an admittedly pretty strong sounding 1 watt or so, 1 watt is still 1 watt and physics is....

In my totally subjective opinion, they are great sounding amplifiers, from low power to high. I own both the SEOTL and T16, both of which sound very similar (to me), but rather different from any transformer coupled amplifier I have made, of which I have many. The kits are extremely intuitive, though I would not recommend one of the amplifiers as a first time project, at least without some thorough practice first. If you need an extremely good tube linestage, the Grounded Grid makes for a more suitable first time project (or a Bottlehead Foreplay, or something else) Alternatively, you could by some passive parts -- resistors, caps, solder terminal strips, some wire, and a piece of wood, and just hook some of the parts together. If you may need a new crossover or want to refresh caps, crossovers make for excellent first time projects due to comparatively much lower parts count, like four or five parts for the Heritage line (the AL excluded from that): couple of capacitors, an inductor or two, a multitapped choke (if your choke is multitapped), or L-pad of some other type. While some have found the SEOTL outstanding in terms of overall sonic qualities, the same 'some' was not satisified with its output ability in very large spaces (I am one of those 'some'). When I say large space, I'm referring to the entire first floor of our open house plan. Listening near field with our La Scalas or Lowther horns, the SEOTL was more than adequate. When turned up quite a bit higher, there were signs of stress, congestion, etc. With the klipschorns in an upstairs listening room (about 16 X 20), it was planty. For a 1.5 watt amp, I was utterly not prepared for the kind of bass control this thing could produce. Better than any conventional 45, 2A3, or 300B amp I've used (which still have something very satisfying to offer for music less heavily laden with bass). The SEOTL is also a great amp for Heresies. Where high power is an issue, the so-called BEAST has been really well received so far, and there is, as mentioned above, the new Mini-Beast. So, something for everyone from a designer who is really bringing something different to output transformerless tube amplification. If you can have a chance to listen before a purchase, that would be great; you might not care for the sound. They use a certain amount of feedback, which does not have the best reputation for some -- I actually thought the same until I understood it better. Sometimes one just has to take a chance and hope for the best, keeping in mind there are piles of alternatives if it doesn't work out. It's just 'stuff,' after all......