The 300b stand alone in sound no doubt, but as for amp type I believe you are right.
The (Un)Official Amp Thread For ZMF Headphones
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bpiotrow13
1000+ Head-Fier
I have even seen 300b, SET OTL amp
Add ZOTL to the list. It’s a different beast altogether. It’s like Pokémon, “gotta catch ‘em all.”
I have an SS and a ZOTL so far. Still need an OTC, hybrid, and OTL.
I have an SS and a ZOTL so far. Still need an OTC, hybrid, and OTL.
I've been super busy lately so haven't been on here much, but I have to clarify amp topologies.
Both SET and OTL are sort of blanket terms for a lot of different types of amplifier circuits.
OTL of course just means there is no output transformer. These are typically single-ended amplifiers too (like SET), most common output stage is a cathode follower, but there are other possible topologies. GOTL, for example, uses an SRPP output stage.
SET can mean a lot of things, but it generally refers to single-ended tube circuits that are transformer coupled. The most common type is called series feed, this is the quintessential SET design. However, other output topologies like parafeed also fall under the SET umbrella.
A 300B amplifier is a SET design, typically series feed, but certainly can be made parafeed as well.
SS and hybrid speak for themselves, most often hybrid circuits use a tube front end gain stage then a solid state buffer output stage. Given the very high transconductance of transistors compared to tubes, they usually do not require transformers for impedance matching.
ZOTL is its own unique architecture.
Both SET and OTL are sort of blanket terms for a lot of different types of amplifier circuits.
OTL of course just means there is no output transformer. These are typically single-ended amplifiers too (like SET), most common output stage is a cathode follower, but there are other possible topologies. GOTL, for example, uses an SRPP output stage.
SET can mean a lot of things, but it generally refers to single-ended tube circuits that are transformer coupled. The most common type is called series feed, this is the quintessential SET design. However, other output topologies like parafeed also fall under the SET umbrella.
A 300B amplifier is a SET design, typically series feed, but certainly can be made parafeed as well.
SS and hybrid speak for themselves, most often hybrid circuits use a tube front end gain stage then a solid state buffer output stage. Given the very high transconductance of transistors compared to tubes, they usually do not require transformers for impedance matching.
ZOTL is its own unique architecture.
What Wes said.The 300b stand alone in sound no doubt, but as for amp type I believe you are right.
One of the nice things about the Woo WA6 & WA6-SE is you really only need to upgrade the rectifier tube and rectifiers last a long time. Yes, you can upgrade the driver tubes, but it impacts the sound less than the rectifier.
Re efficiency: all the amps in your price range will perform best with efficient headphones. ZMFs are plenty efficient to work with any of them. The WA6 and WA6-SE have output transformers which give you more flexibility on driving lower impedance headphones. The WA6-SE puts out a lot more power than the WA6, which gives you the option of powering some not particularly efficient headphones. That said, in my experience both the WA6 and WA6-SE perform best with either very high efficiency planars (like the Audeze LCD-X) or dynamic headphones with an 80 ohm or higher output impedance. I prefer a fairly neutral sound though and if you like it warmer, you can go to lower impedance dynamic driver headphones.
I guess the biggest reason you might consider a transformer coupled amp is they tend to be more neutral and they can handle a wider range of headphone impedances. Amps with no output transformer (like the WA2) tend to be warmer, but they also tend to be more 3D sounding with more detail.
Another exotic topology out there is the Schiit Folkvangr. No longer made and above the O.P.’s price target, but it’s an unusual OTL amp that uses a total of 10 tubes and some electronic magic to support a wide range of impedances. It’s not the most powerful amp out there (1.4 W max) but it’s good enough to power all my phones and has some OTL sound characteristics like excellent imaging and detail.
bpiotrow13
1000+ Head-Fier
I do not know if this is always the case but this is exactly my experience and the reason I stongly prefer OTL apms. I really feel there is some magic behind OTLs
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Guarddawg30
Head-Fier
It isn't that it kills, but when you take that first blast you want to chase that dragon forever
AudioDuck
Headphoneus Supremus
Folkvangr, aka “The Tube-Eating Unicorn”.
AudioDuck
Headphoneus Supremus
While I don’t mean to start debate on this, I will point out that some people [cough- like me] would also recommend a fuse change as well.
I respect all points of view on this, just wanted to add that it’s a possible upgrade path , similar to cable upgrades, that is available- whether you feel inclined to use it or not.
jonathan c
Headphoneus Supremus
^^ Not necessarily. I have found that the Woo headphone amplifiers that have tube rectification (WA2 otl, WA6 otc, WA6SE otc, WA22 otc) are greatly affected by the choice of rectifier tube. With WA2, for example, there is to me an audible difference in ‘warmth’ when using Mullard EZ81s versus using Tesla EZ81s. EDIT: I would also add that the Linear Tube Audio ZOTL MZ3 is not inherently warm. It can be made so with RCA 12SN7s and RCA 12AT7s.
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yeah, the difference between the Airmid and La Figaro 339, for example, is night and day, both of which are OTLs
The 339 is uber gooey and warm, whereas the Airmid is well, airy, clear, transparent and revealing. Probably the most revealing amp Ive ever heard, tube or otherwise.
The 339 is uber gooey and warm, whereas the Airmid is well, airy, clear, transparent and revealing. Probably the most revealing amp Ive ever heard, tube or otherwise.
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While I don’t mean to start debate on this, I will point out that some people [cough- like me] would also recommend a fuse change as well.
I respect all points of view on this, just wanted to add that it’s a possible upgrade path , similar to cable upgrades, that is available- whether you feel inclined to use it or not.
I’m game to learn anything, but want to understand the science and theory behind it - what does changing fuse do to the audio signal path?
Thanks
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