[Joe Garfield]

I'm trying to choose an amp for my digital piano and HD6xx. I started with Magni then changed to Vali and like how it affects note decay, so I want to try a full tube amp.

One of the limitations is that this will sit on a small shelf in close proximity to the piano. The shelf is 8x8 (amp can overhang front to back if absolutely necessary) and there is just under 10" between the side of the piano and the wall. I don't want to ruin the piano from tube heat (or burn the shelf!) There should be a pic attached to illustrate. I really prefer not to see electronics when I play, so I'm trying to avoid having amp on top of piano (which is 11" deep.)

*The Little Dot MKII is the best choice in terms of fit and aesthetics, is easily affordable, but it seems worst for tube selection/matching and overall sound/quality.
*Darkvoice is biggest and heaviest, maybe biggest heat concern, but it fits aesthetically and I like that it's dual triode (instead finding individual matched tubes for LD).
*Bottlehead Crack is best for sound/quality/customization, worst aesthetics, most expensive and longest lead time.
*Valhalla is widest (9") so the vent would be very close to piano, it's most expensive, might not have the same decay, but it's a nice quality amp in a nice package.

For this situation, which would you choose?

Thanks!
-Joe

 

[tomb]

As long as you don't try to put a tube amp under that shelf, you should be OK with any of them. The majority of all heat will reject above, not below. Even if an amp is designed to reject heat through the case, the shelf will be insulated by the feet.

Keep in mind that a single tube amp is a compromise and comes with its own problems. It may seem counter-intuitive to you, but matching two tubes for equal output is way easier than finding a single, dual-triode tube with matched triodes. Of course, you want the matching. Otherwise, you could have an irritating channel imbalance in the amp. I have tested literally two or three thousand tubes in the last 10 years. Unfortunately, very few have closely matched triodes within the same tube. It's the exception, not the rule.*

* With dual-triode tubes, the typical stereo two-tube amplifier connects both triodes in each tube in parallel, so you end up having the average of the two triodes per tube for each channel. That means in searching for matched tubes, you average the tested outputs of the two triodes in each tube. I don't remember my probability mathematics, but averaging the outputs from a single tube significantly increases the chances of finding matches with another tube.

 

[buke9]

HD-6XX’s and Bottlehead Crack = Awesome period. It is the best amp that I have heard for them bar none. The next one would be a Drop Cavalli Tube Hybrid doesn’t give you the awesome mids with the Crack but ain’t half bad .

 

[Joe Garfield]

It's been a little while since I started this thread, but I ended up ordering the BH Crack. From what I read, Valhalla sounds like what I want (clean, not particularly tubey-warm but still has tube properties) but I would never stop wondering about the Crack. The top plate and bell housing are being powder coated and should be done today. I ordered Speedball and also some updated audio capacitors, but will install them sequentially. Hopefully the base amp will be done this weekend.

 

[buke9]

It's been a little while since I started this thread, but I ended up ordering the BH Crack. From what I read, Valhalla sounds like what I want (clean, not particularly tubey-warm but still has tube properties) but I would never stop wondering about the Crack. The top plate and bell housing are being powder coated and should be done today. I ordered Speedball and also some updated audio capacitors, but will install them sequentially. Hopefully the base amp will be done this weekend.

Wow you went all in didn’t you. You should have built the base Crack first before even the Speedball to make sure everything was right first.

 

[Joe Garfield]

That’s my plan, I haven’t built it yet. I just ordered parts in preparation.

 

[buke9]

That’s my plan, I haven’t built it yet. I just ordered parts in preparation.

Build it in order.

 

[DenverW]

It’s good advice to build the stock crack first, then upgrade bit by bit. Crack, speedball, caps. I would give at least 1-2 weeks in between each upgrade. Make sure to do all your voltage checks and make sure each step works perfectly for a time before moving on. it can be a challenge trying to troubleshoot and repair stuff after you’ve made a bunch of changes.

 

[Joe Garfield]

Yeah that’s the plan. I want to build it per the instructions, check it out, get my ear used to it, then make incremental changes. Speedball first update, output caps second, then if I’m liking it I’ll think about a choke and PS cap. If I’m not in love with Crack, I think selling it with Speedball and updated caps is a nice package to offer. But I imagine it will have it’s place, somewhere around the house or office.

I just got the plate back from powder coat. Unfortunately it warped so hopefully the coating won’t eff up when I try to straighten it out. And hopefully the build will start this weekend, if we’re not getting hammered by this hurricane.

 

[Joe Garfield]

It's built! Resistance and voltage checks were spot on nominal. I'm glad I built it stock. It sounds great, and I still have more to look forward to.

Impressions, in order:
"Holy crap I can't believe how quiet this thing is!"
"Woah, there's BASS!"
"Hmm, I bet this thing will let me hear more difference between DACs." -Changes from SDAC to Mimby: "Holy s41t I was right."
"Did I just hear AIR? Oh yeah, this is a live recording from a concert hall, not from inside a box!"
"I think I can see Hillary Hahn's violin bend a little..."
"It's not just the amount of bass, it's like I can hear each of Mike Gordon's bass strings independently vibrating. They're loud, but not overpowering."
"The sound difference is concentrated at the bottom end. The black background lets more detail and ambiance shine through, but the extra power and impedance match responds mostly with the bass. I wouldn't mind a little more treble sparkle. There's always crack, and output caps...oh wait, I have a tube to roll!"
"There's 2 beautiful Polynesian women singing in my ears. It tickles - i they get any closer I think I'll get wet! I don't care, it feels sooooo good!"
The next day: "I can't believe how much I loved my $80 DAC and $60 Schiit amp when I got them - I mean, they're not bad, but I just don't see them the same way."
Looks at S.E.X. online, but realizes the K712's probably won't scale nearly as well...

 

[Joe Garfield]

Jesus - that was all before anything was burned in. The amp and headphone pairing is wonderful - the best sound I've ever heard.

Tidal Masters > Lightning/USB > Schiit Modi MB > BH Crack > Senn HD650

 

[DenverW]

And now....let's talk tubes

 

[Joe Garfield]

I can't for the life of me figure out what tubes came in my kit. The 12AU7 is labeled Baldwin, I thought maybe a Raytheon but I'm not so sure. And I'm leaning toward GE for the 6080, mostly because of the spots in the label, but can't find another identical tube to confirm.

 

[DenverW]

I can make a few recommendations on tubes based on what your budget is, and what type of music you like. Also, what caps did you get? I can also help with a couple of really cheap upgrades you can do for fun once everything is done if you still want to tinker a bit.

 

[Joe Garfield]

I bought a "Tung-Sol Chatham 6080" that supposedly is NOS, but the measurements written on the box aren't the best :/