SET vs OTL amps - which one offers true "tube" sound?

Most tube preamps/phono stages/headphone amps will only be dissipating a few watts. The amount of heat they give off won't be much more than a 40 or 60 watt light bulb. There are going to be exceptions to this.

jeff

 

Linear Tube Audio is making ZOTL based amps (under license). I've been wanting to try the MicroZOTL 2 headphone amp to find out what it sounds like. They also have a couple of ZOTL based speaker amps.

 

I don't think there are many if any tube phono pres or hifi pres with output transformers. Unnecessary. They might have some buffer circuit on the output, maybe coupling caps, but not output transformers. Basically all the tube preamps you're likely to run into are going to be free of output transformers. Its not really like there's a special class of OTL preamps with unusual circuitry needed to get sufficient and and sufficiently low impedance like with OTL amps. Typically they're just running a couple of small signal tubes. Use little energy and dissipate little heat.

 

Just throwing this out there ... Decware makes an OTL preamp called the CSP3 with 2 sets of RCA inputs and with an excellent headphone amp.

I would take Decware ZP3 phono and CSP3 preamp over the stuff you listed as I tend to prefer their circuit designs, tube, caps and resistor compliments over the others. IMO the chassis is better looking (subjective of course) and with a better warranty as well.

 

My custom-built preamp has transformer outputs. I heard versions of the same design with capacitor coupling and transformer coupling and the transformer version sounded best so I went in that direction (one option was to get both forms of output). Also influencing my decision was the fact that I planned to purchase (which I did) an amp that had complementary input transformers (the amp would not work well with most preamps that did not have output transformers). I don't know if too many production companies utilize output transformers, perhaps Allnic does. Theory aside, good transformers can sound wonderful, even when such is not "necessary." But, good transformers are not cheap.

 

K&K has transformer coupled tubed Phono preamps. The Maxxed-Out is the one he builds and the Trio is the kit he sells. Kevin is a peach to deal with. I see he also builds a line stage that utilizes transformer coupling.
K&K Audio | »

 

Yeah, I'm personally not opposed to transformers for voltage step up or step down, isolation, impedance matching, isolation, etc, wherever, and I know there are some hifi tube preamp designs that might use transformers on the input or on the output or both.. transformers are a good tool for the jobs that they are called on to do....and yeah good transformers are often very expensive (although relatively smaller ones that you might use on a preamp output probably need not be crazy expensive). Like anything you might use in an electronic circuit, they have pluses and minuses. But I just think the OP may be a little confused about the terminology or nature of the designs when he asks "would OTL make a good phono preamp" or refers to things like the Transcendent Grounded Grid pre and phono pre as "OTL preamps" -- they ARE, of course, output-transformerless, but it's not a phrase we would commonly use to describe them or any other common tube preamp almost all of which don't employ output transformers. OTL tube amps are peculiar, uncommon designs that go to great lengths to avoid using OTs . "OTL preamps" are basically almost all common hifi tube preamps. In that case transformer coupled preamps are the uncommon design.

 

In my 20+ years in this hobby I've found that tube amps are all about the iron and the design. Good output transformers of course are huge but so are good chokes and interstage transformers. Going OTL is not worth it in anyway to me. Too many trade offs and inconveniences for too little gain. I've only heard a handful of tube preamps with output transformers but as long as the they're designed well they will always beat cap coupled preamps in my book.

 

I like both the Transcendent Sound phono and pre-amp. Both are easy kits to build. I had a variety of phono stages, all less than $400 and the Transcendent Sound was better, but cost a little more. My Grounded Grid sounds wonderful for the price. I have had no issues with it for the eight years I have had it, and I use it every day. Starting over, I would consider the new Masterpiece by Transcendent Sound. The Grounded Grid does have three transformers though.

 

Since you're looking at single ended gear and because I'm hoping I'll finally be able to post a picture here. I'll plug the guy I'm getting my amp from. The picture that hopefully shows up is my amp burning in.

 

Maybe use a flash next time.

jeff

 

Its actually still at Tool Shed Amps. He just shot me the picture showing it all a glow.

 

Really cool.

Just curious, how much input do you have into the patterns he puts on your amp? Does he choose one, does he give you some to choose from or what?

 

Yes some interesting looking amps on the Toolshed website.

jeff

 

I think he only has a couple of wood and metal choices available for his entry level amp but you can have pretty much whatever design you want on the amp. Then from his mid level amp on up the line you can have whatever you want. Check out his Instagram. Lots of pictures of the guts of his amps too.

Matt Formanek (@toolshedamps) • Instagram photos and videos »

The appearance of mine is totally custom. The transformer cover actually has a logo from my kids favorite book series. It's polished copper and Leopard Wood. The brass and Bacote, and the aluminum and Black Walnut are my other favorite combos.

 

Power transformers though. Not signal transformers.

 

I'm not confused, but rather - ignorant. I'm just starting to learn about all this stuff, and I learn by reading. Reading internet resources, forums such as this one, and reviews. I am a strictly "consumer-type" audiophile, if I can call myself that at all. I know I love music, and God knows I have a lot of it, and I also love good audio equipment, at least to the tune of my budget. But - none of this technical stuff you guys seem to be so comfortable with. I cannot, like some of you, look at a schematic of an amp and understand anything from it. Neither do I pose as a knowledgeable techie. All I know is I'm shopping around to upgrade my system, and every manufacturer's website I visit has nothing but superlatives to describe their wares. Every one of them claims their amp provides "best sound for the price" and that "nobody else can possible even come close at this price", and similar pet phrases. SET manufacturers praise SET designs, OTL makers - OTL. Others - accordingly. I read it all, and it seems that everyone is "best". We all know that cannot be the case. That's why I decided to go directly to the end-users, and gather some opinions and experiences, and maybe learn something from it.

For the most part - that's the case. But you seem to especially enjoy rubbing my nose in it every time. I already know that I know very little, you don't need to remind me of it every time with phrases like "OP is confused" and alike. I came here to ask from people who do know, not to be reminded that I don't.

Thanks for your input, but I believe I've had as much of it as I can digest.

 

I'm not disparaging you in anyway. You're taking me all wrong.

 

Tube amps can be intimidating if you don't understand them. I don't understand them and I've shied away from considering a full tube amp for my headphones because of that. I've dipped my toe in with hybrid amps. But hybrids are a different sort of thing than the full tube amps. So I understand and can appreciate Benzion's trepidation and uncertainty about tube amps and how to choose what tube amp.

For the past year or two I've been looking for a second very good headphone amp to pair with my hybrid Cavalli Liquid Fire amp. Something with a different sound but still with a sound style that suits me. I thought, OK a good SS amp will do it. Except I haven't heard one yet with the sound I'm after. The Schiit Ragnarok has come the closest. The more tube amps I hear the more I realize that a full tube amp is probably what I'm after. But I'm still intimidated and unsure because I don't understand the things well enough.

Fortunately since I go to local headphone meets I've been able to hear very good tube amps of various designs. I've heard some very very good OTL headphone amps. Some very nice SET amps. And some very nice tube amps of other designs. But I still don't understand what's all going on and what would be best for me. And then once I get the amp, how do I deal with it? It's the sort of thing that can cause paralysis by analysis.

 

The one that best suits the impedance of your headphones, and sounds right to you.

There's really nothing to deal with, other than turning it on and off. Most tubes will last for years before they need to be replaced.

jeff

 

Unfortunately I have multiple different headphones. Low impedance, high impedance, ortho magnetic, and others that I'll have in the future. I need an amp that is able to drive all of them with the sort of sound that I want. I don't want an amp that is only good with one of my headphones or some of my headphones.

Some amps require bias adjustments. I don't want to have to deal with that. If I have to buy a special insulated screwdriver, a multimeter, and other tools to maintain the amp then that is not an amp for me. The voltages inside those amps is frightening. I ain't going anywhere near that sort of voltage without knowing exactly what is going on and how to do it safely (what does it mean to drain a capacitor and how do you do it?). I don't know how to do that and I don't want to have to know how to do that.

Tube rolling isn't rocket science, but does require some knowledge and experience. The first recommendation for many tube amps is to change from the stock tubes. Yikes! If you don't have a big stock of tubes on hand to try that means buying new tubes and trying some. That gets to be expensive and full of mystery and black magic as you try to learn what tubes will work and what won't and which ones will sound best of what you can get for a reasonable price.

I understand how this tube amp thing can get intimidating. It doesn't need to be. But it can be. And when you're new to it, it will be intimidating.

 

I take it back then. Had a bad moment. Sorry.

 

They look good, are well priced, and am sure they sound great, but their ad copy really puts me off:

"Removes Digital Harshness. Adds Lushness to Vinyl."

Sorry, but my digital front end doesn't sound harsh, and my vinyl rig doesn't need any lushness adding... I'd be looking for far more transparency in a tube amp, than what they are stating here.

 

Sorry if you took any kind of offense to my comments. Not my intent at all.

Of course every maufacturer is going to tell you their designs are the best. Not only are they trying to sell something but they probably believe that their approach IS the best, that's why they used it. But there's such a range of types of circuits out there -- and most commonly encountered production hifi tube amps are neither single ended triodes nor OTLs but rather push-pull amps using pentodes or tetrodes. Each design has advantages and disadvantages and each probably has adherents who have some near religious faith that one or the other approach is the only path to audio nirvana. In truth though you won't find unconditional consensus about what's best because there are great amps of each type and as many opinions about them as there are listeners. It's always a series of compromises -- more power or less power, lower measured distortion vs no negative feedback, ability to deliver power into tricky loads, and of course price (retubing an OTL can cost a lot and they're so inefficient that they use a lot of electricity; quality output iron costs a fair amount of money). Enjoy the search and take any any assertion that one or the other type of circuit is the only true way with a grain of salt.