Moabs are a lot of speaker for the money. I have the Ulfs. They are very responsive to different cables. You may want to experiment with that for more detail. Also Eric is a big fan of Bi-Wiring speakers. The Ulfs come with two pair of input posts to encourage that. I didn't think it would make a difference, but Eric encouraged me to try it and it did. I think the Moabs and the Ulfs use the same mid/high components even-though the Ulf is a 4-way design. If so, yours are capable of a lot of detail.
I haven't got your system, so can't comment on it, but I built the B1K and played with it, and we had your DAC in another system...
The B1K sound can be tuned.If you like it not too soft, more neutral and with extended frequency response, while still keeping the beauty and transparency of this little jem, I found the following made quite a difference:
1- Adjust the bias closer to the H2 null point than recommended
2- Replace the lytics in the signal path with PPP caps
3- Fit a SMPS filter
All this has been documented in my previous posts in this thread, if interested the Search function is your friend.
Further, we picked up your DAC in the up to 500$ bracket after some entensive listening with other DACs, "thanks" to the first lockdown we had. Fine unit, way better than the other chinese we had. We had some plans to tune it though as not perfect enough and quite a step from my own reference in my main system. Before we just started tuning it, it proved to be unreliable re volume control on one channel when going more than 20dB attenuation, so we tested other DACs again, in a higher bracket, and found that the D70S was quite an improvement over it. It replaced your DAC (returned in warranty and refound). OK, a bit more expensive, but sounding now damned close to very serious DACs (air gets thin at that level) while way better built (we opened both...)
I hope this helps
Claude
The B1K sound can be tuned.If you like it not too soft, more neutral and with extended frequency response, while still keeping the beauty and transparency of this little jem, I found the following made quite a difference:
1- Adjust the bias closer to the H2 null point than recommended
2- Replace the lytics in the signal path with PPP caps
3- Fit a SMPS filter
All this has been documented in my previous posts in this thread, if interested the Search function is your friend.
Further, we picked up your DAC in the up to 500$ bracket after some entensive listening with other DACs, "thanks" to the first lockdown we had. Fine unit, way better than the other chinese we had. We had some plans to tune it though as not perfect enough and quite a step from my own reference in my main system. Before we just started tuning it, it proved to be unreliable re volume control on one channel when going more than 20dB attenuation, so we tested other DACs again, in a higher bracket, and found that the D70S was quite an improvement over it. It replaced your DAC (returned in warranty and refound). OK, a bit more expensive, but sounding now damned close to very serious DACs (air gets thin at that level) while way better built (we opened both...)
I hope this helps
Claude
I've built various tube preamps ending with the B1K as my favorite tube unit. I did a lot of H2 tuning on the B1K, settling for just a bit on the neutral side of the recommended positive phase H2 level setting.
But since I built the BA2018, I haven't been able to go back, for all the reasons you mention, as well as the tighter and more extended sounding bass the BA2018 seems to offer.
The interesting thing is how the B1K sounds so very enjoyable on its own. But when you put it in a level matched A-B switched setup up against the BA2018, you begin to hear what's missing that's being filled in by the B1K's excellent H2 character. If musicality combined with excellent detail is your goal, it's hard to do better than the BA2018.
I've built three BA2018s now, mostly so I can A-B different power supplies. Two have the large output transistors and headphone jacks. I was surprised to find that in an A-B against my Whammy HPA, the Whammy (with Burson V6 Classic front end) always wins as a headphone amp. And yet when using the Whammy as a loudspeaker system preamp, the BA2018 always wins.
I don't know about the BA18 gain but one thing you might want to consider is that despite its highish gain (16dB or so), the B1K doesn't like to see really more than say 2V at its output.
It can deliver 4V or so, but then distorsions get very high IMHO.
IMHO this circuit works best below 3V output
Claude
It can deliver 4V or so, but then distorsions get very high IMHO.
IMHO this circuit works best below 3V output
Claude
Agreed that the Moabs are a LOT of speaker for the money. My Moabs are bi-wired and I am using them with bi-wired Kimber 12TC knockoffs. But to be honest, I've struggled to hear the difference between speaker cables although I have a pair of Chinese ribbon cables coming later this month that I am looking forward to hearing.
Surprisingly to me, I do hear clear differences with USB cables and power cords. That makes no sense, and perhaps it is all in my mind, but since swapping those cables out my system sounds better than ever.
I wish it were possible to do an A/B comparison of the Ulfberhts and the Moabs, I've always been curious about the difference. But lately, I have been seduced by the Wilson Sasha DAWs and am wondering if I can really justify spending that kind of money on a speaker.
I have the Topping D70 DAC in another system but I've never done an A/B comparison with the SMSL-SU9. I do have the Denefrips Ares II and comparing that with the SMSL-SU9 really strains my ability to hear differences. Because of its remote control I am using the SMSL as the DAC on my main system. I've had no issues with reliability or setting the volume level as low as 35.
I'm curious if you have an opinion about the best way to attenuate volume with a DAC and a source like Roon which also lets you adjust volume?
I'm curious if you felt the BA2018 with the large output transistors was an improvement over the standard version with loudspeakers?
Bring the Moabs over! You're really close to Houston, right? Not...
The difference could be in the crossover too. I would HOPE there is some pretty high quality stuff in the Ulfs. The more I do DIY speaker construction the more I realize just how important the crossovers are. In fact Active Crossovers have made some really bad sounding speakers sound good in my experiments. Maybe we should ask Eric for specifications so we can do active. Plus that will give us an excuse to build three or four more Pass amps too!
Yep, posted on that somewhere here a few month ago, search function is your friend... even implemented it at my friend Gilles.
Basically we performed blind volume compensated listening tests on various modern DACs and found the following to our ears:
- depending on source resolution and ears, digital volume control worked perfectly on modern DACs until say -35dB to -40dB, and that finding was quite stable including on the D70S or lower range DACs (or somewhat older qualitative DACs).
- from there on there was an audible loss, regardless what manufacturer claim, to our ears.
The qualitative best (and possibly cheapest) volume contol we came up with was hence a clever mix to cover our attenuation range and listening ability. The beauty is the calculation we did... differed very little for other systems as long as you have a digital source with reasonable gain chain and LS with less than 100dB/m/W efficiency (or so, depending on listening habits). Otherwise simple calculations need to be performed to adjust the 2 ranges below.
The solution is a simple switch with 2 resistor networks / fixed attenuators, with high quality resistors and wired directly. Say long gear and short gear. Both are say 35dB apart.
Short gear is what you need most of the time. You have a constantr 35dB attenuation (or so, can be altered so you do'nt end "in between gears" when listening to various materials that may not be equally loud). From there on you adjust the volume with your DAC, so you get perfect -35dB to -70dB attenuation in fine steps. In practice we use the DAC's volume position at Gilles around -10dB with pop or rock, which is ideal: some headroom for lower recorded materials without standing up, -25dB attenuation available to hav quite listening without loss (and below our ears are rather the limit).
Want party level? Listening to unusaly quiet classic recordings? Long gear in, you get ideal control from 0 to -35dB (or whatever you prefer). Of course you can still be leazy and go further down re attenuation without switching, but then at the increasing cost of quality. Or just stand up and put short gear back in. In practice short gear is always in, long gear only for parties or fun mode for one song or so, gets very loud usualy.
Works great and was a clear step upwards to the Blue Alps we still use for non digital sources. I am building a preamp with various options, from active to passive preamps, and with Tocos (or my old faithfull Black Alps) as attenuator either way... or the switch I just mentioned.
Need all this to play as I have a TT and also a DAC with fix output...
Again, more details and parts listed in a post some months ago, I believe it was the Aiyama 04 thread...
I hope this helps
Claude
Basically we performed blind volume compensated listening tests on various modern DACs and found the following to our ears:
- depending on source resolution and ears, digital volume control worked perfectly on modern DACs until say -35dB to -40dB, and that finding was quite stable including on the D70S or lower range DACs (or somewhat older qualitative DACs).
- from there on there was an audible loss, regardless what manufacturer claim, to our ears.
The qualitative best (and possibly cheapest) volume contol we came up with was hence a clever mix to cover our attenuation range and listening ability. The beauty is the calculation we did... differed very little for other systems as long as you have a digital source with reasonable gain chain and LS with less than 100dB/m/W efficiency (or so, depending on listening habits). Otherwise simple calculations need to be performed to adjust the 2 ranges below.
The solution is a simple switch with 2 resistor networks / fixed attenuators, with high quality resistors and wired directly. Say long gear and short gear. Both are say 35dB apart.
Short gear is what you need most of the time. You have a constantr 35dB attenuation (or so, can be altered so you do'nt end "in between gears" when listening to various materials that may not be equally loud). From there on you adjust the volume with your DAC, so you get perfect -35dB to -70dB attenuation in fine steps. In practice we use the DAC's volume position at Gilles around -10dB with pop or rock, which is ideal: some headroom for lower recorded materials without standing up, -25dB attenuation available to hav quite listening without loss (and below our ears are rather the limit).
Want party level? Listening to unusaly quiet classic recordings? Long gear in, you get ideal control from 0 to -35dB (or whatever you prefer). Of course you can still be leazy and go further down re attenuation without switching, but then at the increasing cost of quality. Or just stand up and put short gear back in. In practice short gear is always in, long gear only for parties or fun mode for one song or so, gets very loud usualy.
Works great and was a clear step upwards to the Blue Alps we still use for non digital sources. I am building a preamp with various options, from active to passive preamps, and with Tocos (or my old faithfull Black Alps) as attenuator either way... or the switch I just mentioned.
Need all this to play as I have a TT and also a DAC with fix output...
Again, more details and parts listed in a post some months ago, I believe it was the Aiyama 04 thread...
I hope this helps
Claude
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I don't think the Moabs or I would survive the road trip from Seattle to Houston LOL. I bought the Moabs with the upgraded crossovers and BE tweeters. I used REW to create a convolution filter to use with Roon's DSP and I think that improves the sound in my room quite a bit. If I ever stop switching electronics every week or two I'll add my subs back in using a DBX DriveRack PA2 to be the active crossover for the subs. It has an equalizer built in and can be controlled by iPad or PC so you can tailor the response for the listening position. My room has a nasty hole at 60 Hz so subs help with that.
I did a very carefully gain matched instantaneously switched A-B comparison between the small and the large transistor versions. Both builds had the identical power supply, a copy of the LED referenced version of the regulated supply used in the Whammy, running around +/-17.2V.
I could hear absolutely no difference between them. I only evaluated them as preamps on a loudspeaker system. I haven't tried that A-B test running them as headphone amps since I really don't use them as HPAs.
That helps a lot. Here is the post that Claude is referencing for those that want to see it:
Aiyima TPA3251 Modification Build Thread !
I haven't really researched attenuators yet but I am assuming that if I used your circuit with a single ended preamp like the B1K it simply fits in between the RCA + in connection and the rest of the linestage? Do you have any idea how you would wire it for a balanced circuit like the BA2018?
Yep, single ended preamp means just inserting for each channel (Left and Right) my simple solution between RCA and the rest of the linestage, just as you would with a conventional pot. It is identical re load etc., just it has 2 high quality positions instead of an unlimited number of positions... that come with questionable contact elements in conventional pots.
I am not using any balanced lines so I didn't think about them yet, sorry...
Claude
I am not using any balanced lines so I didn't think about them yet, sorry...
Claude
Playing with polarity
My nagging curiosity got the better of me so I built a little box to test the effect of inverting the polarity between my B1K and ACA. In short it's similar to what I hear when inverting speaker polarity on the ACA- loss of soundstage, loss of detail and dynamic range. Everything compresses down and sounds more monophonic. It's a subtle effect but strong enough to lead me to believe I could pick out the inverted polarity in a blinded A-B test. Note, my B1K is biased at 9.5V to produce positive-phase second harmonic distortion.
In a brief test of a transformer-based passive preamp, I didn't hear any effect from switching polarity.
My nagging curiosity got the better of me so I built a little box to test the effect of inverting the polarity between my B1K and ACA. In short it's similar to what I hear when inverting speaker polarity on the ACA- loss of soundstage, loss of detail and dynamic range. Everything compresses down and sounds more monophonic. It's a subtle effect but strong enough to lead me to believe I could pick out the inverted polarity in a blinded A-B test. Note, my B1K is biased at 9.5V to produce positive-phase second harmonic distortion.
In a brief test of a transformer-based passive preamp, I didn't hear any effect from switching polarity.
Attachments
So....
My nuTube has failed again, pretty much exactly as previously described (https://www.diyaudio.com/forums/pass-labs/313612-b1-korg-triode-635.html#post6598822).
Same channel. Was careful to measure and set the voltage at the test point to 9v.
Suggestions for troubleshooting? It would be nice to be able to do some informative probing without having to replace the nuTube.
Or should I go ahead and build the Wayne's BA2018 linestage (or the Elekit tube preamp)? Attraction of the Elekit is it would eliminate the need for an outboard phono preamp.
-- Thing
My nuTube has failed again, pretty much exactly as previously described (https://www.diyaudio.com/forums/pass-labs/313612-b1-korg-triode-635.html#post6598822).
Same channel. Was careful to measure and set the voltage at the test point to 9v.
Suggestions for troubleshooting? It would be nice to be able to do some informative probing without having to replace the nuTube.
Or should I go ahead and build the Wayne's BA2018 linestage (or the Elekit tube preamp)? Attraction of the Elekit is it would eliminate the need for an outboard phono preamp.
-- Thing