Bottlehead Forum
Bottlehead Kits => Mainline => Topic started by: Doc B. on April 30, 2013, 01:53:26 PM
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Last year we retired the Smack headphone amp kit due to sluggish sales. There were a lot of really good aspects to that kit - adjustable output impedance to handle a wide range of headphones, both single ended and balanced headphone output, a single gain stage circuit with active loading and hybrid shunt regulation, and very good transformers. And very good sound - I thought it was clearly our best sounding headphone amp at the time. Unfortunately for Smack we revamped the S.E.X. kit and in doing so came up with an amp that pretty closely matched Smack sonically and offered enough power (2W!) to run tough cans like LCDs, HEs and K1Ks.
Smack's lower gain and 1/10 the power output was a compromise in the name of greater resolution and speed and more quiet operation. And we somewhat compromised the kit with a very functional but standard stereo volume pot to keep the price down. These things worked against the kit and our customers were buying S.E.X. instead for the same price.
So I decided to rethink the concept of a more premium headphone amp. I wanted to keep the positive aspect mentioned above, and I wanted a bit more gain and more power, and a better attenuator up front. We also had heard a lot of folks ask for extra inputs and express a dislike for our impedance switching setup that required turning the amp off and going inside to adjust output impedance and balanced/SE output.
And so here you see the prototype of Mainline, our new premium headphone amp. It uses 6C45pis as the power tubes and a 12AU7 as the two channel hybrid shunt voltage regulator. The 6C45s and the shunt reg are both loaded with C4S active loads. Zero global negative feedback as usual and parafeed transformer output using the same OT-3 we used in Smack. There is a switch which sets the output impedance for low or high impedance headphones, one that sets the output to single ended or balanced, and a source selector for two sets of single ended RCA inputs. Output jacks are both from Neutrik - that kinda obnoxious but very fancy locking TRS jack that tweakers seem to fancy for their Crack kit, and a four pin XLR wired in the standard AKG K1000 pinout for the balanced jack. The attenuator is the same as used in our Submissive 36 step attenuator with six coarse 9dB steps and six fine 1.5dB steps for a total of 56 dB attenuation. Output power is about 600mW. Input impedance is 25Kohms minimum.
I'm using it with HD800s with both balanced and single ended cables. It is clearly more resolving and much more quick and punchy than the very good sounding Smack amp that I kept for myself when we retired that kit. Bass is tighter and the top end is more open while the natural midrange is at least as good.
Kit pricing is expected to be around $1000 - just about what one would have paid for a Smack kit and a Submissive kit if they had coexisted, plus the step up to a 6C45pi configuration.
I'll be showing the prototype at the Seattle Head-Fi meet at the West Seattle public library this Saturday.
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You really seem to know how to get my hard earn cash. If this does sound better than the Smack, and if I can use it for my planars, I'll be one happy man with a $1000-lighter wallet.
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Very Cool! Bottlehead has been releasing some great stuff so far this year. I might need to track down another K1000 again to pair with this amp.
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Very nice, are these going to feature Bottlehead output transformers? Any thoughts on how it performs compared to a S.E.X. with stepper and Magnequest iron? That's definitely been my go-to amp for quite a while now.
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Yes, this uses the OT-3 output transformer that we used in the Smack. That is a transformer that has been tweaked for headphone use. I think the new amp will sound better than S.E.X., with higher resolution and a more dynamic and clean presentation partly because of the single gain stage and partly because of the shunt regulation and active loads. It costs more, and our philosophy is if it costs more it it should sound better. I have not tried it with K1000s. K1000s are ultra nearfield speakers more than headphones, they want speaker type power levels. I think they sound best with Paramounts and very good with S.E.X. I will try my K1Ks at some point - who knows? maybe I will be pleasantly surprised - and I should have a report on how well the amp works with LCD2s and HEs after Saturday's meet.
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Hmmm, these are 8k primaries. I may grab one and build it it with my 8k B7s, just like keto did with a Smack. For the loaded-with-iron office system.
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In this application they are operating as 4K primary impedance. For what it's worth. It doubles the ratio of inductance to resistance giving (in theory!) better bass. The transformer was designed to work well over the range of 4K to 8K.
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The B7 step down ratio is pretty shallow compared to the OT-3 we designed the amp for. The Mainline is heavily regulated and is just DEAD quiet with HD800s on the high impedance switch setting, that is 64 ohms output impedance. But I don't know if the S/N ratio with a B7, even at the 150 (or is it 125?) ohm tap will be as good. By the way I prefer the OT-2 (4/8/16/32) in the S.E.X. over the OT-3 (16/32/64/128) for the same reason - on the highest impedance configuration (128 ohms) some hum comes through the S.E.X. That tap is hardly necessary with a 2 watt amp anyway, the 32 ohm tap will blow your ears off with 300 ohm cans. If you are using your Sonys I think the OT-3 will be a better match than the B7 anyway.
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I'm thinking of it as a pre. For the Sonys I have the very first Mainline which was modified for 437A, remember that one? The B7 is 600 ohm on the secondary. In any case I have other projects before and I'll just put the B7s in the, since today, idle fp3.
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My experience indicates that BeePre is a better preamp, and Mainline is a better headphone amp. Headphones require an OT. A preamp does not. If you can avoid a transformer without having to use a cathode follower instead - i. e. you can create a plate follower with low enough output impedance for line level use - that will work a wee bit better. As for the 437A amp, yup, mainline is a close relative. Would be interesting to compare. That amp has some really great parts. Mainline doesn't have the exotic tubes/iron/caps/etc. but has a couple of tricks (balanced output, a very competitive attenuator) that might get it pretty close.
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Oh, I'm sure that the BeePre is a better preamp, just by concept. But for my office I'll be using cds and the more iron I can put in there the better. In my main system I'm enjoying a Beepre already.
I have not used the 437A amp with its matched repro yet as I had some trouble with the Ampex 300. But that deck is working now and I'm sure I'll starting enjoying it a lot very soon!
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I get the concept you are shooting for. But I don't know that the OT-3 would help smooth the sharp edges of a digital system. They are really open on the top end. Where the 300B as plate follower beats out the transformer output preamps is on the bottom end, it's tighter and more punchy. That's not just vs. the OT-3, every transformer I have tried at line level is a little softer on the bottom end than a plate follower.
BTW if you are going to put 8K B7s in your FP3, why not convert it to a tube that is a better match for them? You don't need the extra triode for the CF, and you really want a tube with a lower plate impedance than a 12AU7. Maybe try 417As?
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It's funny, I'm just not a headphone guy. I have tried a few times to get into it, but end up with the regular set up with speakers each time. The odd part is, headphones offer the greatest detail one could ever want, AND there are no room acoustics and such to mess with. When I see designs like the one described here, I get tempted. I mean when it's done right, there really isn't an equal.
My curiosity would be greatest to hear a headphone system that was balanced, all the way from the phono cartridge to the headphones themselves. That's a little out there, I know, since the resolution is already incredible, but I just can't help the 'what if' gene.
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Nice name :) more "reference" sounding...
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Yeah, but reference to what?
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fphotos.foter.com%2F103%2Fmainlining-cocaine_l.jpg&hash=859943773935294ec1f826bd89c8cd51c56224a6)
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BTW if you are going to put 8K B7s in your FP3, why not convert it to a tube that is a better match for them? You don't need the extra triode for the CF, and you really want a tube with a lower plate impedance than a 12AU7. Maybe try 417As?
Hmm,
I'll post in another thread (More "how to add transformers" questions) to stop hijacking this.
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Is that a Larry Clark?
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Dunno, just grabbed the first pic I spotted on a google search.
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Hmmm, just after I sold my hd-800s and considering selling the Crack, and as I'm listening to the new Fostex T50 RP "alphadogs" this looks very, very tempting!
I am really absolutely loving these new cans -- different than the hd-800s, but truly beguling in their own right, and at significantly less than the 800s. So much so that I jusst also got a pair of the balanced version. And man, are these comfortable to wear as well. Could very well be my new personal reference headphones, and this new amp looks like just what they need. :-).
Don't get me wrong, the Crack/HD-800s is one of the great pairings ou there and I'll never say anything bad about either, or the pairing, but in a total about face in my headphone journey, the planars just feel even more *right* to my ears.
How nice of you to come up with a great amp for them :-).
-- Jim
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Jim, are you saying the $200 Fostex are in league with the $1500 HD800s? (After some mods, I presume, but still!)
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Hi Sam, yes, I think they are in the same league. That doesn't mean they're the same -- to my ears and at this early stage, the hd-800s have the better soundstage, but the "alphadogs" are said to improve significantly in this area as they break-in. I also think the "dogs" have a somewhat warmer, but still very detailed presentation, and better bass -- very tactile bass, which seems to be one of the hallmarks of orthos. They are also closed back and isolate you from a good deal of outside noise, and likewise don't disturb others near you -- really the reason I decided to try them so I could have some closed back headphones for listening in bed. I also find them extremely comfortable and hold their adjustement well. They are a bit of a skull clamp at first, but even wearing them for the last 3 days they have already loosened up some. They are $300, not $200. Balanced version are $350 pre-order, and $400 once they begin to ship. They don't sound very good with the Crack, but the s.e.x. should be a great match. The unblanced version also comes with 2 cables -- one 1/4" and one 3.5mm -- no adaptors, two separate cables.
Bought mine from stereodesk.com -- an authorized dealer, who deals directly with the manufacturer.
This is probably a bit off topic here, so if you want to talk more about them, start a thread in the headphones forum.
I'm really taken by these, even as new as they are, which is odd for a guy who never really liked planars/orthodynamics and closed back cans. I've heard the stock and other modified verions of these and they are not at all like these. These are serious cans despite their relatively low cost.
-- Jim
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Yeah, but reference to what?
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fphotos.foter.com%2F103%2Fmainlining-cocaine_l.jpg&hash=859943773935294ec1f826bd89c8cd51c56224a6)
LOL,priceless
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Dollar for Dollar,they are probably the best closed headphone on the market
When I had the mjolnir/gungnir combo...I l;listened to them for 6-8 at a clip..
Sorry,they do not sound that great with the crack/speedball, ,,,though
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Dollar for Dollar,they are probably the best closed headphone on the market
When I had the mjolnir/gungnir combo...I l;listened to them for 6-8 at a clip..
Sorry,they do not sound that great with the crack/speedball, ,,,though
Why is it they don't work so well with the Crack?
Besides being closed-baffle, what else would distinguish them from the HD600s (which I have)?
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Not 100% sure.
Maybe its because the alphadogs are an ortho headphone,and,the Hd600 is a dynamic headphone???
Not sure the crack can drive the ortho headphones,but??correct me if I'm wrong.
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The alphadogs are only about 50 ohms or so impedance -- the Senns are 300 and the Crack was designed for high impedance headphones.
-- Jim
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Sooo, I went to stereodesk and looked at the those wonderful headphones and dam there is the balanced version that I would like. Now the question is, how do I go about powering them with BH products? Yah, maybe I'm not so much a headphone guy, BUT when I do choose to listen, I want the best that I can get.
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Dollar for Dollar,they are probably the best closed headphone on the market
When I had the mjolnir/gungnir combo...I l;listened to them for 6-8 at a clip..
Sorry,they do not sound that great with the crack/speedball, ,,,though
Why is it they don't work so well with the Crack?
Besides being closed-baffle, what else would distinguish them from the HD600s (which I have)?
I also am really enjoying the Mr. Speaker Mad Dogs with the alpha pads. They are quite smooth and very easy to listen to for long sessions, both via comfort and sound. For me, however, they a sort of a special purpose headphone. I use them specifically when I want/need a closed set of cans - ie. - when there is minor noise in the house I want to block out, late at night, and when I'm at my home desk. When I want to do more serious listening I go back to my HD600s.
The Mad Dogs suffer with an OTL amp. My desktop Schiit Valhalla couldn't drive them well at all, not surprisingly. Being orthos they really need some oomph from the amp. My new Schiit Lyr with NOS tubes makes them sing. But again, for serious listening I always go back to my Crack/HD600 combo.
The HD600s are (to me) the better headphone - more soundstage & detail, faster and better bass - but I heartily agree with the above - the MDs are without a doubt a great headphone for under $300.
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Listened to LCD-2s with the Mainline at the Seattle Head Fi meet today. Works great.
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Sooo, I went to stereodesk and looked at the those wonderful headphones and dam there is the balanced version that I would like. Now the question is, how do I go about powering them with BH products? Yah, maybe I'm not so much a headphone guy, BUT when I do choose to listen, I want the best that I can get.
You could use the SEX amp, the Mainline, or Paramounts...
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So excited for this amp. Can't wait for its release. Just sold my W3000ANV's and my LCD-2's so plenty of fun money ready for it.
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Sooo, I went to stereodesk and looked at the those wonderful headphones and dam there is the balanced version that I would like. Now the question is, how do I go about powering them with BH products? Yah, maybe I'm not so much a headphone guy, BUT when I do choose to listen, I want the best that I can get.
Might be time for an amp upgrade..??
Sex Kit..???
I went through this when I bought the HE-6's..ended up buying an emotiva mini 100 amp ,just for those cans...
Good luck.
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I'm pretty sure this amp will drive at least the fostex maddogs and the he-400s no problem, and probably the he500s ass well. Others I'm much less confident about, but if doc said they did fine with the lcd 2s, then I wouldn't worry about anything but maybe he-6s.
Dan,
How closely matched will the 6c45pis have to be? The Russian firecracker is a ggreat tube, but they measure all over the place and it can take some work to get a nicely matched pair.
This is sounding a lot like your old primo headphone amp!
-- Jim
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Heck, Jim, that's kinda like asking how closely matched a woman's breasts need to be. If it's a pair that gives you pleasure, then I think it's a good match. I used to think this forum was kind of like a car forum, i.e., what mod will give me the fastest 1/4 mile. But I have come to realize it's kind of like a wine forum, or maybe a wristwatch forum. So many of the choices are a taste thing.
So I'm sitting in the listening room this afternoon, spinning a nice minty mono pressing of Jimmy Smith's Organ Grinder Swing. From the sweet spot the image is dead center. From the rear seat it seems to pull right. PB comes up to the room and I ask him to sit in the rear seat and tell me where the image is. He finds it dead center. Who's right!?!?! Like fingerprints, everyone's ears are a little different, and things like tube matching are pretty tough to generalize. FWIW part of the reason we use a C4S is that it helps to make tube tube try to hit the maximum mu specified in the manual.
Hopefully folks who want to tweak the amp to the last degree will find the price of 6c45pis reasonable. I haven't owned more than a few pair myself, but they never failed to impress.
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That is my favorite Jimmy Smith LP Dan. Great dynamics and swing!
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Actually one of my favorite albums, period. The opening phrases of Organ Grinder Swing is my ring tone. I've been diving headfirst into soul jazz lately. Actually I have loved it since I was a kid, but now I have the reason and means to dig deep. Aside from all the B3 gods like JOS and Groove Holmes and Dr Lonnie Smith and Jimmy McGriff and Jack MacDuff and Papa and Joey D, one obscure jewel of a B3 player I have discovered is a guy named Bobby Floyd out of Columbus, OH. Last couple of tracks on Notes to and from My Friends are smokin'.
And there are some major B3 talents who have been around for years but maybe not too well known in the US. One who knocks me out is Rhoda Scott.
And another obscure track I love is Paul B. Allen, Omaha Nebraska from Buddy Miles' Them Changes. Andre Watts was the B3 player on that, and it really grooves. Killer soul jazz right in the middle of a classic 70's R&B album.
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Thanks Dan, I've been wanting to explore B3 artists further. I have to agree with you, it's one of my all time favorites also and Kenny Burrell on guitar doesn't hurt :) My favorite track is "Oh No Babe", man oh man can he make that organ sing! I had hoped you would pick this recording instead of "Sermon" for the TP release. Glad to know there are a few other B3 fans around :)
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Thanks Dan, I've been wanting to explore B3 artists further. I have to agree with you, it's one of my all time favorites also and Kenny Burrell on guitar doesn't hurt :) My favorite track is "Oh No Babe", man oh man can he make that organ sing! I had hoped you would pick this recording instead of "Sermon" for the TP release. Glad to know there are a few other B3 fans around :)
If we could get it I would campaign for it. It's a Verve (as is a lot of great JOS stuff), a label we simply haven't yet had the opportunity to work with. Whereas The Sermon is from Concord's vault, who have been exceptionally supportive of the Tape Project from the start. And yeah, getting Kenny Burell on an album is obviously something we like too. And Jimmy and Wes would be awesome too. OGD, baby, anyway you spin it that's a serious way to do some blues.
Don't overlook all the other great B3 players. Lonnie Smith comps like nobody else, and Groove Holmes didn't get the nickname Groove just because he liked to listen to vinyl. There's a whole universe of great organ jazz out there if it's yo' thang. And yeah, I think I can guarantee it will all sound good on a Mainline.
And you know I have Hammond in the music room at home, yes?
http://m.youtube.com/watch?v=40mHviJFEyw&feature=plcp
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Just stumbled over the cuatro de mayo thread on head-fi and was thrilled learn about the mainline - as well as to read all the positive feedback on the bh dac prototype!
Sounds like I'm going to have start saving my pennies (and buttering up the wife) ;)
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"Yeah, but reference to what?"..... hahaha great photo!... spot on...
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Doc, with these 2k plus dollar amps out there from manufacturers... would it be safe to say that if you designed and machined a fancy aluminum chassis, boutique caps etc... and sold it through the same circles that the mainline would probably be in the 2k plus range also?? I imagine it would be..
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It's hard for me to say "it would cost in the $2K range" without looking at the possibilities. My hunch is it would cost more, as we have paid as much as $1000 for a cabinet once or twice. What I can say is that the circuit is basically the same as a statement headphone amp that I built 10 years ago, that sold for $7500 (though we have learned a few new tricks since I built that one). Obviously the parts are not as exotic as in that big amp, which had Daven attenuators, MQ autoformers and power transformers, a huge copper vein coated aluminum chassis with a custom lacewood front panel, vintage Dakaware knobs, custom Jupiter parafeed caps, EL84s for shunt regulators, etc. etc. But the design is quite similar.
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That amp had a "forever service policy" though :)
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fwww.bottlehead.com%2Fsmf%2Findex.php%3Faction%3Ddlattach%3Btopic%3D3607.0%3Battach%3D2545%3Bimage&hash=6364dd98d12056d56d2e223838b057dc9e70da0d)
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And man, did it sound fantastic! Eh, Xavier ;-).
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Yes, and the forever service policy allowed us to incorporate some of the things that we learned in the ten years following.
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Plus the change to exotic we437a to match the other exotic parts!
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Ok great stuff.. thank you Doc.... Yes, i would imagine more than 2k also, i was trying to be on the low side.. this is very cool news and shows again just what an incredible value BH gear is.... Cant wait to get building the FEW kits i have on my list after i get settled again somewhere....
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What are the optimum impedance for headphones being driven by the Mainline? I have found my SEX to wonderful with a variety of headphones from 50ohms up to my K240DF which is 600ohms, but the best synergy is with lower impedance headphones where the Crack weaker with my lower impedance headphones.
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It can handle any headphone from 32 ohms up. I would say the sweet spot is more a matter of what headphone you prefer than a particular impedance. So far everything I have tried has sounded quite good - Grados, ATs, Senns, Audeze.
I would say it's a more neutral amp than SEX or Crack. So if you have a headphone than needs some fattening up in the bottom end to get it balanced those might be better choices. But the Mainline will give the best resolution and sense of dynamics.
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Plus the change to exotic we437a to match the other exotic parts!
would the we437a work in the mainline?
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We have not sized the chassis holes to accept the sockets for the WE437A, but you could punch out the 9 pin socket holes and install larger sockets (I have first hand experience doing exactly this in roughly the same circuit).
The Mainline has lots of room under the chassis, so I wouldn't expect one to run into any issues with a mod like this. Other than the different pinout, the circuit will not need any alterations.
-PB
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Thanks... I gotta start saving for the mainline now!
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Hey Doc - I was just curious what 6C45pi's you recommend for the mainline and what the kit will ship with. Are EH goldpins the tube of choice or are the Sovteks just as good/better? Do any other manufacturers make them? Thanks!
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Just got some EH's in. Internally they seem to be identical to the tubes we have been getting from Russia and Ukraine.
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Thanks Doc! If and when you get a chance, I'd be curious to know whether you perceive any audible differences between them?
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I must correct myself. We got Sovteks not the goldpins. They sound just the same as the other 6C45pis we have. IME the gold pin EHs are different only in that they have gold pins.
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My pre-amp died, I have read here that the Mainline is tailored to headphones and the BeePre to amps but will the Mainline drive a power amplifier with this input?
INPUT SENSITIVITY: 0.8V RMS for rated output at 1kHz.
INPUT IMPEDANCE: 47kΩ.
It is a SS Plinius SA-100 100W/ch class A power amp driving Magnepan speakers. I used a headphone amp (the one that died a The Max Headroom) as a preamp for years and it did a very fine job. I had people dead keen to sell me a preamp that would bring out a demo model of something costing twice as much as The Max and they knew instantly on hearing my setup that they could not touch it.
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Yes, the Mainline will drive a power amp, quite well, even with very long interconnects.
During our investigation of better preamps, the Mainline configuration (shunt regulated, current source loaded, single ended triode with parafeed output transformer) would probably have won, if Doc B had not kept pushing for a 300B. The BeePre circuit with other triodes was not quite cutting the mustard. Because a headphone amp needs an output transformer, we went back to that configuration for the Smack, and eventually refined it as the Mainline.
I love the sound of the BeePre, but if I didn't have one I'd use a Mainline, or a Smack, in a heartbeat.
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Yes, the Mainline will drive a power amp, quite well, even with very long interconnects.
During our investigation of better preamps, the Mainline configuration (shunt regulated, current source loaded, single ended triode with parafeed output transformer) would probably have won, if Doc B had not kept pushing for a 300B. The BeePre circuit with other triodes was not quite cutting the mustard. Because a headphone amp needs an output transformer, we went back to that configuration for the Smack, and eventually refined it as the Mainline.
I love the sound of the BeePre, but if I didn't have one I'd use a Mainline, or a Smack, in a heartbeat.
So if one wanted to get a great headphone amp AND a great pre-amp, would the Mainline be an option?
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If you want our best preamp get BeePre. If you want our best headphone amp get Mainline. If you want both, mainline can do it but will require an adapter from the headphone jack.
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If you want our best preamp get BeePre. If you want our best headphone amp get Mainline. If you want both, mainline can do it but will require an adapter from the headphone jack.
That is great to learn - I definitely want to buy or build an adapter. Are details of an adapter to connect a power amp to the Mainline available?
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If you want our best preamp get BeePre. If you want our best headphone amp get Mainline. If you want both, mainline can do it but will require an adapter from the headphone jack.
Interesting. But the BeePre couldn't have a headphone jack added? How close is the design of these two? You should make a Mainline/BeePre hybrid with three inputs and headphone jack.
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The designs are different. Mainline is optimized to run headphones and has a high gain tube with an output transformer. BeePre is optimized to drive amps and has no output transformer. Because of this the BeePre has too high an output impedance to drive headphones of less than 600 ohms impedance. But it has a little bit better resolution and realism. The adapter to go from a stereo 1/4" headphone jack to a pair of RCAs from the Mainline is like 90 cents from Monoprice.
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Looking as you have Neutrik SE input connectors on the Mainline, how easy / hard would it be to build a balanced input? You just need to swap out standard Neutrik D XLR female jacks in place of the RCAs. Of course you'll probably need another circuit board to handle a transformer-less or transformer balanced input.
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Looking as you have Neutrik SE input connectors on the Mainline, how easy / hard would it be to build a balanced input? You just need to swap out standard Neutrik D XLR female jacks in place of the RCAs. Of course you'll probably need another circuit board to handle a transformer-less or transformer balanced input.
You can always ground the cold pin on the XLR and use it that way.
There may also be room to mount a pair of input transformers on the Mainline to handle the balanced interface as well.
-PB
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You can always ground the cold pin on the XLR and use it that way.
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Only if the source uses a transformer output without a grounded centertap. Otherwise you will short one phase of the balanced source, and probably short it to chassis ground, not signal ground, as well.