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45 tube based amp, comments/opinions ?

post #1 of 51
Thread Starter 
Hey guys,
I have a friend who wants to build a dedicated headphone amp for me, based on two 417a as Pre/Gain tubes, and two 45 for the output, they are intended to suite my low impedance and high sensitivity Audio Technica cans. (W11PN & W5000).

He has some rectifier tubes in mind, I forgot the model name :/

What do you think of this combo and particularly on the 45 tube as output ?

I would also like to know if you know any amp that uses the 45 as output tube, there are probably some for speakers, but I wonder if there were any for headphones
I remember there is a 300B amp, which his quite exclusive, or am I wrong ?

My guy is a true tube guy who is mainly influenced from Sakuma and Kundo from AudioNote Japan, he plans on utilizing as much transformers as possible and as less caps as possible (sakuma style).
He likes using 300B and 845 tubes but he said the 45 is more linear but has 1/3 of the 300B output, therefore is great for headphones (which requires a low wattage) but not that good for speakers.

The amps is planned to cost around 1300$, the cost is mainly parts cost.

I got too much into technical, which is not my strongest part, I leave it to my friend

I would really appreciate your comments.

Thanks
post #2 of 51
Quote:
Originally Posted by Mr.Shadow View Post
He likes using 300B and 845 tubes but he said the 45 is more linear but has 1/3 of the 300B output, therefore is great for headphones (which requires a low wattage) but not that good for speakers.
That's an incomplete statement and should read "not that good for speakers IF speakers are not very efficient." 45 SET will make an average of 1.5 watts per channel, so for realistic dynamic range and headroom, the speakers really need to be in the 98-100dB sensitivity range with stable impedance.

If those conditions are met, 45SET will simply rock your world with speakers. After you spend some time with 45SET/right speakers, you will likely not be able to go back to the colorations of 300B/845SET. One can get away with 93-95dB speakers by using the 45SET to biamp the treble/midrange only, which is what I used to do with my Kornef 45SET.

You are lucky you have this "friend," but it is kind of risky as far as resale value since your friend is likely not famous. On the upside, he sounds like he knows what he's doing. Input transformers, interstage transformer coupling, GREAT output transformers will usually lead to great sound. He's probably using some kind of directly-heated rectifier like 5U4G, which he should.

Hey, maybe you should build a small "run" to reduce parts costs and offer some to head-fier's
post #3 of 51
Quote:
Originally Posted by Jon L View Post
That's an incomplete statement and should read "not that good for speakers IF speakers are not very efficient." 45 SET will make an average of 1.5 watts per channel, so for realistic dynamic range and headroom, the speakers really need to be in the 98-100dB sensitivity range with stable impedance.

If those conditions are met, 45SET will simply rock your world with speakers. After you spend some time with 45SET/right speakers, you will likely not be able to go back to the colorations of 300B/845SET. One can get away with 93-95dB speakers by using the 45SET to biamp the treble/midrange only, which is what I used to do with my Kornef 45SET.

You are lucky you have this "friend," but it is kind of risky as far as resale value since your friend is likely not famous. On the upside, he sounds like he knows what he's doing. Input transformers, interstage transformer coupling, GREAT output transformers will usually lead to great sound. He's probably using some kind of directly-heated rectifier like 5U4G, which he should.

Hey, maybe you should build a small "run" to reduce parts costs and offer some to head-fier's
Nevermind .... Jon beat me.

$1300 in parts typically translates into $5000 retail. The only downside is 45's are getting rarer by the day and already run about $100 or so per tube.
post #4 of 51
You’ve described a Yamamoto A-08S but it’s not for headphones.

“two 417a as Pre/Gain tubes, and two 45 for the output,”

http://www2.117.ne.jp/%7ey-s/A-08S-NEW-eng.html

“45's are getting rarer by the day and already run about $100 or so per tube.”

You can get nice pairs of ST type 45’s for less than $100. The Ballon tubes from the 1930’s are going for about $250-$300 a pair.


“$1300 in parts typically translates into $5000 retail”

Maybe but not the Yamamoto, I think I can identify $1300 in parts alone on that $2600 amp- the ebony legs are worth $50 each, the Yamamoto Teflon tube sockets are about $50 each. Ebony encased capacitors, custom C-core transformers. Amazing value for the money.

I believe the DIY kit is about $2100.


Good Luck. Some one else was working on a 45 based headphone amp? Len maybe?

Mitch
post #5 of 51
Thread Starter 
Quote:
Originally Posted by Jon L View Post
That's an incomplete statement and should read "not that good for speakers IF speakers are not very efficient." 45 SET will make an average of 1.5 watts per channel, so for realistic dynamic range and headroom, the speakers really need to be in the 98-100dB sensitivity range with stable impedance.

If those conditions are met, 45SET will simply rock your world with speakers. After you spend some time with 45SET/right speakers, you will likely not be able to go back to the colorations of 300B/845SET. One can get away with 93-95dB speakers by using the 45SET to biamp the treble/midrange only, which is what I used to do with my Kornef 45SET.

You are lucky you have this "friend," but it is kind of risky as far as resale value since your friend is likely not famous. On the upside, he sounds like he knows what he's doing. Input transformers, interstage transformer coupling, GREAT output transformers will usually lead to great sound. He's probably using some kind of directly-heated rectifier like 5U4G, which he should.

Hey, maybe you should build a small "run" to reduce parts costs and offer some to head-fier's
Many answer for me now, here goes:
You are more than right Jon L, when I said that 45 is not that good for speakers, I meant to say that it's not that practical for speakers, they need to have very high efficiency and stable impedance as you said.

According to my friend, he said 45 tube can produce about 3W per channel, it is more than enough for headphones.

To the matter affect, he likes transformers so much because he makes them himself.
He buys the cores and than calculates and makes all the lapping, I actually think he is good at it, well, at least he sounds like he knows what he is doing, when he speaks to me, I get about 20-30% of what he speaks,

according to him he talked about Underict heating, I don't remember if he was talking about the rectifiers or the output tubes them self.
he also mentioned fixed bias he wants to use compared to auto bias.

He already built 2 amps based on 300B, he is definitely not a rookie

I actually can't really be losing here, as he said he wants to built it and it will probably be way better than all the stuff in the price range, as they will never use so many transformers and some other methods/tubes, it will cost way more than 1000-2000$.
About resale, I believe it will be a good amp and even if I won't like it, I think it will be sold able pretty easily.

When he started to talk about the design (cosmetically) I just couldn't help myself from desiring it
Black brushed aluminum with some red cherry wood on the sides to match my W11JPN, damn, it will look top notch !

He really likes music and amps/tubes, he is not just a person who knows a thing or two about electronics and tubes, he is a good guy.

Earl, the prices of the tubes are not that bad, compared to 300B, they are in the "reasonable" realm, IMO.

braillediver, thank you very much for the link, I will show it to my friend, I'll see what he has to say about it, he is very excited to try this out
post #6 of 51
The 45 is indeed something special. There are plans for a 45 DIY amp in the Glass Audio Project Book (http://www.audioxpress.com/bksprods/products/bkaa62.htm, $7.95) that I've been toying with. I think it'd sit well with the K-1000.

Only thing is, the 45 ain't cheap and I'd imagine the NOS supply will dry up and make the prices skyrocket in a few more years. I don't know if I'd want to be put in the position of either not using the amp or dropping $1k to retube it. That's why I've been leaning more towards building a 2A3 amp. They also sound very good and I'd be able to affordably lay away a stash of tubes for the future. Not so with the 45.

Do any of you think the 45 might go back into production, like the 2A3 or the 300B? Or is it too much of a niche tube for a manufacturer to make a buck from? Then again, a healthy supply of them would reignite interest. Does anyone have thoughts on that?
post #7 of 51
“Do any of you think the 45 might go back into production”

Already has and is getting Rave reviews. It might be $400 a factory matched pair but I believe it comes with a years warranty.



http://www.emissionlabs.com/datasheets/EML45.htm

They also make a mesh plate 45. The tubes have been discussed or reviewed by 6moons.


"Only thing is, the 45 ain't cheap"

Any of you guys actually buy a 45 tube in the last 6 months? I have. I've bought 8 recently. The most expensive was $280 for a matched pair of Radiotron UX-245's, balloon shaped from the 1930’s. The rest averaged $40 each for matched pairs and matched quads. And a pair of those were RCA Cunninghams with engraved bases.







A question with out any basis is- “why hasn’t anyone made a 45 based headphone amp yet”? I think I’ve seen just about everything else so I wonder if there’s any technical issues in producing a 45 based headphone amp?


Mitch
post #8 of 51
Thread Starter 
Quote:
Originally Posted by braillediver View Post
A question with out an basis is- “why hasn’t anyone made a 45 based headphone amp yet”? I think I’ve seen just about everything else so I wonder if there’s any technical issues in producing a 45 based headphone amp?
Mitch
Mitch, good question...
I don't think so, but it makes me even more tempted to try

Thanks for all the info about the tubes.
If I will go for it, I will start with so cheapo (about 40$) tubes just for the heck of it, if I'll like it, I don't care about buying some good and reliable tubes.
post #9 of 51
Quote:
Originally Posted by Mr.Shadow View Post
Mitch, good question...
I don't think so, but it makes me even more tempted to try

Thanks for all the info about the tubes.
If I will go for it, I will start with so cheapo (about 40$) tubes just for the heck of it, if I'll like it, I don't care about buying some good and reliable tubes.
If you are for sure going for the 45SET, you might want to just buy a pair of EML 45 solid plate tubes now and have your builder do a couple of things to take advantage of this tube, which is capable of more power if the circuit is optimized to it.

Most people quote 1.5 wpc to 2 wpc for 45SET, but even at 2 wpc, we're talking pretty high distortion numbers. 3 watts are "possible," but out of a normal 45 tube, we are talking 5-10% distortion! NOS Globe 45? Even less clean power. Clean 3 watts are possible if the amp is built around the EML solid plate. Maybe your friend can install a switch to flip between 2 operating points, one for "normal" 45 and one for EML solid plate. I would recommend this if you were going to use this amp with speakers also (or K1000, which needs more power than from normal 45 tube BTW). For usual headphones, there is no need to get 3 wpc.

Yes, I did use the EML solid plate 45 tubes in my amp, and I consider it one of several tubes EVER produced that truly defines tube greatness. My eyes are welling up with mist just thinking about it
post #10 of 51
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

post #11 of 51
I heard the 45 tube for the 1st time today in a Moth si2a3/45H. It sounded fantastic with my Grado HP-1000's
post #12 of 51
45s are sexy tubes, they'll make you a very happy man.

I'm not sure 417As are the best choice of driver for it (not to say they aren't nice sounding tubes, of course), if it was me I'd use a 47 (which is pretty much a pentode version of the 45) instead. 47s are still (for now at least) pretty cheap.
post #13 of 51
Thread Starter 
Thanks for all the info, I will try to consult with my friend and see what he has to say about it.

This sounds jolly good
post #14 of 51
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.
post #15 of 51
Thread Starter 
pftrvlr, you basically say that tubes which are good/excellent to speakers are not necessarily as good for headphones ?
It might be, who knows.
High End is trial and error until reach the extreme.

I can't see how they are an overkill, it's about 2W at max, you will need about about 1/4 of the power, makes sense to me.

But hey, I'm just the messenger
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