MLA

Many thanks, that looks exactly like it! Did some more reading and that O2 mod seems quite similar to how the M3 bass boost is implemented. I have a spare Dynalo in the basement to experiment with; I will give this approach a try and see what comes out of it.

I did, and that works perfectly when I've got the place to myself and can turn up the volume. However, my social setting requires low volume listening more often than not. At those levels, I need a small bass boost to preserve balance. It's just for convenience; with a switch on the amp I would not have to walk over to the computer to change settings .

On a tangent; the HD800 sound brilliant out of the Dynalo, but I find myself boosting the bass a couple of dB most of the time for it to sound right to my ears. So far I've used digital EQ, but I wonder if someone has a recommendation for how to incorporate a small add-on circuit/daughterboard that could fill the same function inside an existing Dynalo build? I know there is a ton of circuit suggestions out there, but I'm not good enough at this to figure out what would work well with the Dynalo.

Well, with that I guess this GB can be considered complete. Happy building everyone! Should there be any problem with the shipments, let us know, and we'll try to sort that out as appropriate.

Everything non-US destined has now been shipped, except for one set of boards which are on hold due to the recipient being out on travels.

Pot boards from US arrived today in good shape, so I'll start shipping the non-US destined pots and boards tomorrow. For some I may not have the shipping address; in that case, you will get a PM.

Too late, already posted them If they don't show by end of next week, let me know.

My bad! I was under the impression everybody ordered boards and never double checked once I got the pots. I see now that of the non-US pot buyers, neither you nor UFN ordered boards. I'll ship to you guys tomorrow.

Nope, done with the baby part Two is enough for me...

No worries, it's wrong in the above post. Pots went to mwl168, not boards The thing missing right now is the pcbs for the pots; mwl168 has sent the non-US pcbs to me but these have not yet arrived. As soon as they do, I'll start shipping pots and boards for the non-US GB participants.

Nice link! I would agree DSD does make less sense for recording and/or storage, and that it's probably in playback there may be differences (i.e. what Kevin said earlier about easier, phase preserving filter implementation for DSD). Jussi Laako who is the guy programming HQplayer says this in the manual: "Some of the more affordable sound cards and D/A converters have suboptimal digital and analogue filters, while still having support for higher sampling rates. Effects of this can be reduced by applying high quality upsampling in software before feeding the signal to the audio hardware at a higher rate. This moves some of the artifacts of the suboptimal hardware to higher frequencies, away from the audible band". "Most modern D/A converters are of the delta-sigma type. Built in delta-sigma modulator of HQ-player allows using DSD-capable converters with this native data format, in many cases bypassing a lot of DSP processing in these converters and allowing a more direct data path to the conversion stage". Since I hear a difference, I guess my hardware just is not up to standard

+1 Would a Stax Mafia DSD only dac be an option?

Looking good!

Quick update: pots to US/Canada are en route to mwl168 for further distribution. Once mwl168 has verified which board buyers are under my shipping jurisdiction, I'll get the non US/Canada board pile and start shipping those out together with pots.

So, pots are in (this is just one of several boxes. Lots of pot...). So far, I've tested all 4CP-601's. I've tested them for channel imbalance when used as voltage dividers in balanced configuration, i.e. the difference in voltage output between the combined output from the first two channels, and the combined output from last two channels. Maximum tracking error in this config for all pots is around 2-3%. However, that 2-3 percent only shows up at the high output levels ( think last quarter of pot range towards full volume). Below that, tracking error is 1 % or less. With the usual reservations for unknown errors in test setup and/or my math, my conclusion is that we got a fine lot of pots this time around. Should you find otherwise when you get your pots, we'll work it out with TKD. I'll ship the US destined pots to mwl168 tomorrow for further distribution with boards in the US, and when the pot boards from mwl168 get here, I'll commence the non-US distribution.

I think I'll focus primarily on channel balance rather than absolute tracking. I'll check a few in the latter sense as well, but of the pots I've had from TKD so far, all have followed the curve quite well.

... and pots are now in (well, at my local post office, but out of the hands of customs anyway, so I can actually pick them up tonight). Will test them during the weekend as well as sort out the pot-boards US-Europe logistics with mwl168 in best possible way to keep shipping rates down.

Well, if I read this correctly, the perfect replica USB protocol used for backups etc (i.e. bulk with checksums) is not what is used for USB audio streaming, so it would appear that packages at least theoretically can get lost or get screwed up when streaming audio over USB (as hinted by CarlSeibert above). http://www.edn.com/design/consumer/4376143/Fundamentals-of-USB-Audio That said, among explanations for why USB audio sound different in some contexts, I think Craig's observations have larger impact than transfer protocol type: https://www.head-case.org/forums/topic/12477-usb-audio-tweaks/#comment-721196 And it happens to be measurable

Got word from TKD; the pots shipped out earlier this week from Japan, and according to the tracking number they are currently being processed by swedish customs. Should have them in my hands in a few days.

I built one as well; I had some boards made when JimL and KG presented the design and board. Powered it with a KGST psu as that's what I had boards laying around for at the time. Very nice amplifier with just a slightly different sound characteristic than others, can very much recommend a build! Dialling it in is interesting as everything is connected to everyhing else. Takes a while to figure out if one of your input tubes is underperforming, which happened to me Also, I have all windings on the same trafo including the filament supplies, and I had to elevate the latter to avoid hum.

Fees paid. Thanks!

Done. Paid, thanks!

Paid. Thanks!

Now column H should be possible to edit, and I've removed your unintended twin Done.

Interesting... Will fix when I get home tonight, editing google docs on the phone is obviously not my thing