300b lovers

@alexberger 

I don't use tube rectifiers in power amps, but I do use them in preamps.  In your amp, if you wish to keep the 5u4g, I would consider using it for the input and driver section and using good quality diodes to drive a separate power supply for the 300b.   I use only regulated supplies, and I have my way of doing it that I don't wish to get into here.  But, yes, it is a good idea to have separate supplies for the input/driver section and the power tube sections.  What sort of supplies is up to  you, but a DHT will echo your power supply AND your filament supply very clearly so make sure they are very good.  

Good luck!

Don

Hi, Lewinskih01!

You bring up two different approaches to system building. One is taking full advantage of modern multichannel DAC chips (8-channel is a common default size) and letting DSP do the heavy lifting. Taking it a bit further, tuning each amp for its own driver, rather than using a AV multichannel amp of marginal quality.

It depends on subjective priorities. Does the speaker need DSP to reach its full potential, and is DAC coloration small change in the overall scheme of things? Can’t say I blame you. Speaker colorations are obvious and gross, and DSP is the most direct and powerful way to attack them.

I have friends who own Altec Duplex 604’s and they don’t like it when I tell them the only way to straighten a 604 Duplex out is DSP ... no physically realizable crossover can fully correct it. Otherwise, you learn to live with the coloration, as Lowther owners do.

DAC coloration ... hoo boy, let’s jump into that rabbit hole, shall we? I feel most audiophiles can barely hear DAC coloration for modern delta-sigma designs ... and measurements are essentially perfect, far exceeding the 44.1/16 Red Book PCM specification. If a modern AKM or ESS converter with a circuit board full of op-amps is perfect for you, you can save big money, and jump on the DSP train with confidence. Do not pass GO, collect your $200, and enter the wonderful world of DSP. Amps built to taste are entirely optional.

Only a few people can hear differences between modern converters, and if you can’t, don't feel bad, you are part of the vast majority of audiophiles. Just buy a $700 Topping or S.M.S.L. and explore DSP. It’s what headphone jocks do these days. No shame in it.

Differences between DACs are weird and extremely subtle, and frankly you have to train to yourself to hear them. I can’t honestly recommend audiophiles go down this rabbit hole. It’s extremely expensive to pursue and full of deliberately confusing technobabble from slick marketers. Maybe not as bad as cables, but still pretty bad. Trust nothing when it comes to DACs, no matter how famous the name, or how glowing the review,

I was shocked and disgusted I could hear what sounded like "big" differences between my antique Monarchy DAC, with its Burr-Brown PCM-63K converters, and the latest confection from the Berkeley DAC (which any Topping will take to the cleaners these days). I also have the exaSound DACs which are ESS based.

I find DAC chasing neither fun nor enjoyable. The best are insanely expensive, and they go obsolete really fast. I might love the $13,500 Mola Mola I heard in the Songer Audio room, but the Mola Mola won’t be worth as much three to five years from now. DACs should be thought of as consumables that depreciate the moment you buy them.

Amps and speakers ... ah, now that is good value. Buy or build a good tube amp (and that certainly includes the $5000 Valhalla from Spatial) and it holds its value indefinitely. Similarly for speakers. The good ones cost more because the parts themselves cost more, and it takes serious design work to make them perform.

Well, enough of the rant on DACs. Addressing the question in the post by lewinskyh01, what does a really good tube linestage bring to the table if the DAC can directly drive the power amps?

A sense of ease, dynamic impact, and sometimes more vivid tone colors. How? Partly better cable drive, partly signal conditioning, scraping off RFI and noise induced in the cables. On paper, op-amps can do an amazing job driving a cable, in practice, not so much. If the preamp passes a quality threshold, yes, it can improve the signal compared to a direct connection to a DAC. Found that out the hard way with first Amity amp.

The magazine conventional wisdom would tell you that clarity and beauty is "euphonic coloration". That’s complete horse****. Euphonic colorations can’t add detail, resolution, more depth, and more in-the-room presence ... colorations can twiddle with subjective tonal balance, and usually adds mush, murk, or grain.

@lynn_olson You might want to play around with this applet:

https://www.falstad.com/fourier/

Select 'sine' and the little dots below the waveform are movable and represent harmonics.

It shows why euphonic colorations (which are only the 2nd and 3rd harmonics) can indeed add to (or subtract from) detail and 'dynamics' and alter your perception of depth and soundstage.

If you only play with the 2nd and 3rd harmonics, and also work with their phase, you see some interesting results. For example if the phase of the 3rd is out of phase with the fundamental, the waveform actually gets taller.

Harmonics define the sound of musical instruments. You can see from this little applet that distortion can bring out details of musical instruments or obscure them.

Lynn,

I appreciate your candid views about the efficacy of DACs at varying price points. I was in the Spatial room when you heaped praise on the Mola Mola dac in the Songer/Whammerdyne room, a far less expensive DAC than the Lampi DAC in your room.  I read an owner's report that a Topping DE90 SE DAC for $900 was, to his ears, pretty much the same as the sound of his DCS Bartok DAC that cost ~12X as much.  My audio pal with nice gear has been is a rabid needle-dropper and he bought this same $900 Topping DAC and now honestly admits that his fealty to only analogue music is over as what he hears with this modestly-price DAC is pretty much the same as he hearing with his $15K analogue rig.

DAC technology, top to bottom, is really fantastic these days.  One of the happiest days of my audio life was getting a SOTA Sapphire vacuum TT in the mid 80's and another very happy day was the day I sold the TT to a local guy a few years ago, no shipping required.  Once I got an Ayre QB-9 DAC in my system, it was game over for my TT rig.