[skeptic]

Supplementing my impressions above, here are the further comments I posted in the crack, sex, mainline comparison thread:
 

 
The mainline retains what I have come to think of as bottlehead's house signature (fast, dynamic and engaging - making your toes tap - with a hint of tube fullness and warmth - the tubes, in a sense, filling in for the room effects you don't get with headphones), but it is just incredibly clean and refined, particularly in its excellent bass response and handling of transients, compared to my modded crack.  This is no doubt the result of its ultra highly regulated single gain stage topology and excellent custom output transformers.  Based on my recollections from CanJam - I would analogize that mainline is as fast, detailed and dynamic as a Zana Deux (leaving slower "tubier" flagships like the Woo 5 in the dust), but with a slightly sweeter top end.  Trumpets still scream when the source material calls for it, but I can't imagine this amp will ever be characterized as even slightly harsh or piercing - which criticisms are occasionally aimed at the Zana.  (I imagine this may mean that mainline has really low high order distortion - sort of the antithesis of the disproportionate glare folks complain of in SS amps with lots of global feedback?)  In any event, these positive qualities essentially mean that the mainline is a perfect match for hd800's to my ears.  Even when listening to very simple music (i.e. the Wailin Jenny's - the Parting Glass), the incredibly clean separation between voices is an obvious improvement over other amps with which I am familiar and makes vocal harmonies that much more enjoyable.  The same obviously applies to fast complex music as well, where the mainline's control and handling of transients is consistently impressive.  The more I listen, the more enamored I become.
 
Hope more of you will have a chance to hear this amp in the near future. If possible, I will bring mine to the So. Cal. meet in March.
 

 
And this was Doc's gracious and highly informative response, as mentioned above:
 

  Thanks so much for your kind words, skeptic! I would agree with what you are describing of the sonics. Mainline was a joint design effort of PJ, PB and myself. In some of our designs I let the guys pretty much dictate the way the amp will end up, for example PB's Crack circuit, or PJ's Quickie. However I kinda fussed and poked and prodded at this one to get exactly what I had in mind. I wanted an amp that was capable as a tool in a critical listening environment, that is to say something I could use for evaluations on my job whether they be equipment or recording quality evaluations. 
 
The OTL approach is very attractive because of its potential for great bass peformance. However OTL headphone amps tend to use cathode followers (including Crack). The CF is a great circuit, you get rid of the potential issues you have with transformers (expense being a big one) but I hear a certain quality to it that is identifiable as cathode follower sound. Same story for multiple gain stages like S.E.X. has, transformer outputs, etc. This also applies to DHTs vs. IDHTs and a lot of other things. Any design is a compromise, and what you are really doing in any design is deciding which compromises are acceptable to your personal taste. Hopefully one can find someone else out there who has the same taste...
 
In this case I felt that we could overcome the potential shortcomings of a single gain stage and having to use an output transformer more effectively than dealing with the sonic artifacts of cathode followers or multiple gain stages. This is the kind of thing you only pick up with experience, you gotta build 'em all and critically listen. I also knew from experience that - though I am still not sure why - the attenuator has a huge influence and needed to be the best we could find. We couldn't find what we wanted so we designed our own, as we did the transformers. Because of that kind of approach to the design Mainline will never be inexpensive like Crack or versatile enough to drive speakers like S.E.X., but I do think it is our best sounding headphone amp.

 
In any event, I aspire to continue updating this thread and cross-posting relevant info to the extent it relates specifically to the mainline (in the event that future readers and potential builders lack the time to read through the entirety of the bottlehead comparison thread).  I continue to soak up as many listening hours with mine as I can squeeze in on any given evening.  It is simply outstanding with hd800's.  

 

[dsound]

Thanks for the impressions Skeptic.  Especially the comparisons with the Crack.  Time to start saving my pennies for a Mainline 

 

[A2029]

Anybody know the current wait time to get the mainline kit??

 

[Doc B.]

Delivery of our products in general runs about three to four weeks. We have a bit of a backlog on Mainlines at the moment as we await a tube delivery from Moscow, so that is probably a fairly accurate estimate at the moment. If you wait a while to orders others will typically have ordered in the meantime, so the wait period tends to remain pretty consistent. It is the nature of a business where we have a lot of different kit products, the more premium of which are not in as high demand as others and thus pretty much packed to order.

 

[A2029]

Cool, a month is not too bad. Ordered

Question: I was thinking of spending some time wrapping a bunch of the cables along the signal path with shielding (and grounding the shielding of course). Do you think this would make any difference? Would it be worth spending the time doing this to eliminate any EMI? If I don't spend the time to do a lot of the wires, are there certain ones that I should focus on that could potentially make the biggest difference? I'm thinking of using a braided shield, and covering it with shrink wrap to prevent any possibility of shorts.

 

[skeptic]

Congrats swich! Rest assured, this amp is as good as it gets.

In reference to your question, I haven't observed any EMI issues with mine (runs dead quiet), and all the main signal wire (a 10 base T variant) and the twisted pair used for the psu wiring are already shielded. Suppose you could add shielding to the two signal wires running from the submissive attenuator to the tubes, but doc or someone else knowledgeable would have to weigh in on whether this would have any audible impact.

 

[A2029]

Another question: Would it be ok to anodize the aluminum plate in this kit? Will probably go with a baby blue or deep red

 

[skeptic]

Anodizing is fine provided that you either do only the top of the top plate or plan to sand it off the bottom side in the various places where grounding tabs are installed (there are quite a few of those). PB discussed this at some point, maybe in the mainline sub-forum on bh's site?

I know Loquah anodized his, as discussed in this thread and depicted on page one: http://www.head-fi.org/t/683012/bottlehead-amplifier-discussion-comparison-thread-crack-sex-mainline/480_30#post_10429737

 

[Sonido]

I've decided this is gonna be my next purchase. I thought about getting a second Questyle to go balanced but I don't think the difference justifies another $1000-1500. Also thought about a better DAC but the Emotiva DC-1 works fine for me. As for headphones, my one-two punch of HD800 and K812 will keep me from anything else for a long time. The Questyle is ideal for my HD800, but not so much the K812. Even the Crack works better for K812, but I know the Crack is less than ideal for low impedance headphones. I'm looking for a good amp for the K812 now, but why not get something that works well with both HD800 and K812. Having great experience with Bottlehead products in the past (Crack and Quickie), I've decided on the Mainline. But I'm in no hurry though, the Questyle is amazing for my HD800 and the Crack has surprisingly played well with the low impedance K812. I'm gonna jump on this next time there's a sale. I think there was a sale back in January for $1000 and should that come up again, I'll pick it up. Otherwise hopefully there will be a 15% off sitewide sale on Black Friday again.

 

[koiloco]

I've decided this is gonna be my next purchase. I thought about getting a second Questyle to go balanced but I don't think the difference justifies another $1000-1500. Also thought about a better DAC but the Emotiva DC-1 works fine for me. As for headphones, my one-two punch of HD800 and K812 will keep me from anything else for a long time. The Questyle is ideal for my HD800, but not so much the K812. Even the Crack works better for K812, but I know the Crack is less than ideal for low impedance headphones. I'm looking for a good amp for the K812 now, but why not get something that works well with both HD800 and K812. Having great experience with Bottlehead products in the past (Crack and Quickie), I've decided on the Mainline. But I'm in no hurry though, the Questyle is amazing for my HD800 and the Crack has surprisingly played well with the low impedance K812. I'm gonna jump on this next time there's a sale. I think there was a sale back in January for $1000 and should that come up again, I'll pick it up. Otherwise hopefully there will be a 15% off sitewide sale on Black Friday again.

You are just looking for justification.  

  Do it now before the better half kicks in.  

 

[skeptic]

I've decided this is gonna be my next purchase. I thought about getting a second Questyle to go balanced but I don't think the difference justifies another $1000-1500. Also thought about a better DAC but the Emotiva DC-1 works fine for me. As for headphones, my one-two punch of HD800 and K812 will keep me from anything else for a long time. The Questyle is ideal for my HD800, but not so much the K812. Even the Crack works better for K812, but I know the Crack is less than ideal for low impedance headphones. I'm looking for a good amp for the K812 now, but why not get something that works well with both HD800 and K812. Having great experience with Bottlehead products in the past (Crack and Quickie), I've decided on the Mainline. But I'm in no hurry though, the Questyle is amazing for my HD800 and the Crack has surprisingly played well with the low impedance K812. I'm gonna jump on this next time there's a sale. I think there was a sale back in January for $1000 and should that come up again, I'll pick it up. Otherwise hopefully there will be a 15% off sitewide sale on Black Friday again.

 
From your various past comments, I think the mainline is an amp you will really love Sonido - with your hd800's as well as k812's.  I will look forward to your impressions, particularly as to the pairing with you DC-1 and comparison to the questyle, once you have her built!  The DC-1 is super tempting, but Bottlehead's dac appears to be nearing its release, and I think I can hold out.  

 

[Sonido]

Oh man idk if Mainline is my next amp anymore. Heard my HD800 through the Cavalli Liquid Glass at a meet and it's something else. To simply put it, it seemed to make normal recordings sound binaural. It's a completely different presentation, akin to going from closed headphones to open headphones, or comparing two channel speakers to a surround sound setup. I didn't find any other setup like this at the meet, and they had some great setups like GS-X mk2 and SR-009 with BHSE. To me, the HD800 and Liquid Glass was by far the best setup there, more so than the Stax. Perhaps I'm just so taken aback by this new presentation where the subtle background details are not only there, but have their own space in the soundstage that I never knew existed, hence sounding binaural. I must admit after hearing this new presentation, I stopped focusing on fundamentals like tonality or transparency, for I was looking to replicate this experience from any other setup. It's quite possible other setups like the Stax are better technically and fundamentally, but they did not give the same experience. Normally things hit that diminishing returns curve quickly and hard by this point, but I can say the differences between say the Crack and the Liquid Glass is quite profound, perhaps even that 10 times in price difference is justified. This was not merely comparing a GT-R and a Veyron where diminishing returns hit hard. This was more like comparing the GT-R to a fighter jet, where the jet does something the car could never do: fly.

 

[koiloco]

^Oh my.  You have found your new love. 

 

[Sonido]

  ^Oh my.  You have found your new love. 

Well first sight (sound?) anyways. Like I said I admit disregarding more conventional metrics when judging the sound after I was wowed.

 

[A2029]

Hi all,
 
Has anyone tried the Audeze LCD-X with the Mainline? Does the Mainline have enough power to drive the LCD-X well?