[Carl]

Quote:

Originally Posted by pftrvlr /img/forum/go_quote.gif Isn't 45 a overkill for headphone? Headphone is usually sensitive enough to work with a 300mw amp. And it will never be able to compete with speaker in terms of sound stage no matter what you do. I think that is why we rarely see 45/2a3/300b tubes even in the most expensive headphone amps.

It doesn't matter if they're overkill. Tubes like the 45, 10, 26, 71A, 20, etc sound really, really good, potentially enough to blow your mind. If you enjoy listening to something, then it is worth it.

 

[pftrvlr]

Quote:

Originally Posted by Mr.Shadow /img/forum/go_quote.gif pftrvlr, you basically say that tubes which are good/excellent to speakers are not necessarily as good for headphones ?

What I am trying to say is that headphone might not be able to take full advandge of 45 tube. Who know if 45 can beat EL84 on a headphone?

 

[braillediver]

“What I am trying to say is that headphone might not be able to take full advandge of 45 tube. Who know if 45 can beat EL84 on a headphone?”

The EL84 is something like a 4 watt tube where the 45 is 2 watts max output.

The EL84 is a Pentode where the 45 is a Triode.

The 45 is legendary for its acoustic properties. Just not usable to many people because of it’s low power output.


Dang- even more so why hasn’t anyone built a 45 based headphone amp?

Mitch

 

[tennisets]

I've got a push-pull 2A3 speaker amp sitting partially assembled at home (took it apart because I didn't do such a hot job on the point-to-point layout first time around). It uses a 76 and a 6A6 driver tube on each side, 5AR4 rectifier.

I can tell you that when I had it assembled, it sounded fantastic. If you've got high enough efficiency speakers 2A3s (and 45s, which are almost the same tube, but less powerful and better sounding according to most) are much better than 300Bs. Headphones are a perfect application for these low powered tubes too, so I'd expect the amp you described to sound very, very good. Interstage coupling is also a great asset. I didn't utilize it in my amp due to cost and size constraints, but it definitely improves the sound even more, as long as you use good iron. Good output transformers are a must as well.

 

[Mr.Shadow]

Ok Guys, I have talked to my guy today.
One thing for sure, I am going for it without blinking, the potential is huge according to most opinions here, and according to him(my friend) too.

The design is as follows:
6 transformers: 1 for power, 2 for interstage, 1 for chock and 2 for output.
The output transformers are suited to 40 ohms, it should be the best match

The decision about the rectifier has changed, now he decided to use 5Y3

All in all, I am pretty happy about this opportunity.

The only one thing we haven't decided yet, is the volume;
He wants to start with a simple but good potentiometer.
I am considering to go with a Goldpoint or DACT 24 level volume attenuator.
Maybe I will upgrade later, in case I'll feel any need.

My friend has a nice collection of RCA 45 tubes from the 40s-50s, they should be good to start with.

Distortion is not much of an issue, as at max, the can will draw about 400-500 mW which is about 1/4-1/3 of the max output.
it should also increase the life of the 45 tubes, which will last about 10 years more or less, it's quite some time if you ask me.

Thanks for all the info and supportive opinions, it means much to me =)

Updates will follow

 

[braillediver]

“He wants to start with a simple but good potentiometer.
I am considering to go with a Goldpoint or DACT 24 level volume attenuator.”

Justin of Headamp hand matches the Alps Blue Velvet pot and he speaks highly of it. I currently have the DACT 24 stepped attentuator in my Aristaeus. A problem with the stepped attenuator is sometimes it’s hard to get the right volume setting. The steps can be larger than desired increment.

It’s supposed to be less of an issue with electrostatic amps and I’ll have to agree there.

I would personally got with a screened Alps Blue Velvet or similar quality volume control or custom build a Goldpoint Stepped Attenuator with the majority of the steps in the range I would normally listen. I don’t think the 24 step DACT would have the resolution you’d like- useful steps in the desired volume range.


Please keep us posted on the progress of your amp?

Mitch

 

[pftrvlr]

Quote:

Originally Posted by Mr.Shadow /img/forum/go_quote.gif Ok Guys, I have talked to my guy today. One thing for sure, I am going for it without blinking, the potential is huge according to most opinions here, and according to him(my friend) too. ... Updates will follow

We are all eager to know the outcome.

 

[recstar24]

Quote:

Originally Posted by pftrvlr /img/forum/go_quote.gif Isn't 45 a overkill for headphone? Headphone is usually sensitive enough to work with a 300mw amp. And it will never be able to compete with speaker in terms of sound stage no matter what you do. I think that is why we rarely see 45/2a3/300b tubes even in the most expensive headphone amps.

I think the general stigma about headphone fidelity in general is that it does not compare at all to speaker fidelity. So a lot of sonic trends with gear that follow speakers, it appears that applying that same trend with headphones would be a "waste."

With headphones, the transducers are essentially directly coupled to your ears, only a couple of millimeters away, bypassing any effects from the room that may be incurred. Therefore, headphone listening is truly very high resolution, and there are aspects to fidelity such as microdynamics, tonal shifts and subtleties, timbre quality as a whole, background details, ambiance, etc., that headphones simply have an easier time picking out and laying on the table then speakers do.

In terms of an amp, the requirements for a noise free/hum free headphone amp are MUCH more demanding than a noise free/hum free speaker amp. Take in point my moth s2a3. Dead quiet on speakers, but on headphones, they pick up the tiny bit of .15 mV of hum that is present. We are talking about 90ish db's for a mere milliwatt of power, compared to 90ish db's for a watt of speaker power, essentially headphones require such a tiny percentage of speakers require it really plays into that theory that the "first watt" is the best and most important watt.

Which now brings us to using esoteric tubes for headphones. I think it's fantastic, and I wish there were more SET amps specifically for headphones, or SET amps that had a headphone jack. The low power of a watt or two is PERFECT for headphones. And due to the high resolution nature of headphone listening in general, that is like taking a 300b or 45 or 2a3 and injecting it right into your ear system, and trust me, man does it sound good! Those tubes just sound so good tonally, so liquid, even and balanced across the whole spectrum, and all the difficulties and quirks with using those tubes with speakers is practically GONE when driving headphones. A 45 tube drviing headphones at 1-2 watts is PERFECT headroom for most headphones out there.

So the question that really needs to be asked is, "Why aren't there more SET type headphone amps out on the market?" I believe there definitely is an interest out there

 

[phergus_25]

Although it is probably one of the cheaper SETs out there I find that my amp really gives me alot of sound for the money. I can only guess at the level of sound that could be achieved with a true 2 grand in parts.
Looking forward to how it goes.
-greg

 

[Mr.Shadow]

Quote:

Originally Posted by braillediver /img/forum/go_quote.gif “He wants to start with a simple but good potentiometer. I am considering to go with a Goldpoint or DACT 24 level volume attenuator.” Justin of Headamp hand matches the Alps Blue Velvet pot and he speaks highly of it. I currently have the DACT 24 stepped attentuator in my Aristaeus. A problem with the stepped attenuator is sometimes it’s hard to get the right volume setting. The steps can be larger than desired increment. It’s supposed to be less of an issue with electrostatic amps and I’ll have to agree there. I would personally got with a screened Alps Blue Velvet or similar quality volume control or custom build a Goldpoint Stepped Attenuator with the majority of the steps in the range I would normally listen. I don’t think the 24 step DACT would have the resolution you’d like- useful steps in the desired volume range. Please keep us posted on the progress of your amp? Mitch

I know how is it to use a 24 steps volume attenuator, I currently have one installed in my MPX3.
I know the problem when one notch is too low, and the one above it is too high, it's tricky, especially when your cans don't require a lot of juice, like now with the MPX3 SLam and the AT woodies...

I will address the options you suggested to my friend, though I think he wanted to use 50K, but I only see the blue velvet in 100K.
he has some brand in mind, I need to recall what was it.



Quote:

Originally Posted by pftrvlr /img/forum/go_quote.gif We are all eager to know the outcome.

I'm sure you all are, maybe even more than me

I will sure do some head to head sessions with my MPX3 Slam once it will be alive

Basically, my friend says he got it all figured out in his head, a guy with a master plan

Quote:

Originally Posted by recstar24 /img/forum/go_quote.gif So the question that really needs to be asked is, "Why aren't there more SET type headphone amps out on the market?"

Your questions summarize a very well explained post, I agree with all of it and I cant wait to get the purity and beauty of the 45 tubes injected directly into my head

I think the reason no amps like this were made before is probably because of the requirements to operate these tubes properly, which is costly. I may be wrong though...

To all of you guys, I promise to update on any change/outcome with the amp

 

[donunus]

Quote:

Originally Posted by mourip /img/forum/go_quote.gif I built a WE417a-Cunningham 371 tube amp a couple of years ago. Tango OPTs, Lundahl interstages, battery bias for the driver, directly heated rectifier. It sounded wonderful with the headphones I had at the time, some Beyerdynamic Dt990pros. The 71 tube only put out about half what the 45s will. I sold the amp and still regret it but I recently bought a SinglePower Extreme and now have the sound back Here is a photo of of the 371a amp.... Anyone out there own it? Best, Paul

hey my cousin owns an amp that looks exactly like that. he has 2a3s on them now. he uses his 45 tubes and it blows me away!

 

[braillediver]

"Why aren't there more SET type headphone amps out on the market?"

Mr. Paul Joppa (P) November 29, 2006 at 20:43:19:

“Re: "the fringe of the fringe", it's true - audiophiles are the fringe, tube audiophiles are the fringe of the fringe, and SET audiophiles are the fringe of the fringe of the fringe. Most of us are seriously wacko - that's why we hang out at the Audio Asylum, not the Audio Mall. :^)”


Mitch

 

[cotdt]

Tell us how it works out! Too bad I'll never get to audition and compare your amp against my single-ended EL84 =(

Anyways, couldn't you just get a 45 speaker amp and change the transformers to work better with headphones? I know plenty of guys who can make the transformers.

 

[Roam]

Quote:

Originally Posted by braillediver /img/forum/go_quote.gif Dang- even more so why hasn’t anyone built a 45 based headphone amp? Mitch

I suspect the problem has to do with hum & noise control, being a DHT they are rather susceptible to these issues which is a major problem especially with sensitive headphones such as Grados. The other thing is the 45 isn't as well known as say, the 300B or 6SN7, at least not here in North America, it's not widespread enough for a company to capitalize on the market. Which is a great pity since the 45 is one of the best tubes around, and it's in current production (the EML 45's are about as good as any NOS tube).

Sidenote: I was going to have my headphone amp built with 45's, but I have a huge stash of 50's so I chose those instead.

 

[cotdt]

People seem to have already solved the hum problem of DHTs with better power supplies. So I still think a 45-based headphone amp would be a great idea!