|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
67.79.69.146
Hi, Folks,
Last week, I finally finished building my brand-new Audio Note Kit 1 300 B SET amplifier. I also blogged the build on my WordPress site.
The amp is still very new and settling in – I don't think it has more than about 10 hours on it. I should also note that it is using the stock tubes, except for having substituted a 274 B which Brian of Audio Note Kits sent me instead of the stock rectifier tube.
The amplifier is a beautiful, heavy beast that seems to be working fine in the sense that all the voltage checks were good, the tubes are all lighting up, and so forth.
The good news is that it is dead quiet – at least with my 92 dB efficient Reference 3A De Capo's I can crank the volume potentiometer as high as it will go and there is absolutely no noise, hum or tube rush coming from either the speakers. Music emerges out of the proverbial black background.
The analog side of my rig also sounds quite great, again with the caveat that the amp still has, according to Brian, at least a couple of weeks to burn in. I have a Bottlehead Seduction Phono Stage.
The trouble I'm having is on the digital side. I am running an old Music Hall CD player as a transport. I also play high-resolution files from my Mac laptop. My DAC is a Musical Fidelity M 1.
What I am finding is that when I play CD tracks that have significant bass energy – and here I am talking about either fat, subterranean synthesizer bass tones or prominent bass drum whacks, accompanying vocals will start to sound like the singer is gargling and the bass also gets a stuttering quality. I assume this means that the amplifier is clipping!
I consulted with Brian about this. He thinks that there is a mismatch between the DAC and the input stage of the Kit 1. He is suggesting that the DAC is putting out too high a voltage and that with the input stage amplifying the input signal 14 or 15 times I am getting a clipped signal amplified. He is suggesting trying a DAC or CD player with an adjustable output for the analog output. By the way, I also tried taking the DAC out of the equation and just running the CD player straight into the amplifier, but the results were not much different. Again, I am not seeing this kind of trouble playing LPs, except, *maybe*, in the opening bars of the LP version of Donald Fagen's "Morph The Cat," which again features fairly exaggerated bass. But that may be my imagination.
As you can imagine, I'm feeling very frustrated at this point, having put hours and hours of (admittedly very enjoyable) time into building this amplifier, not to mention that the kit is not cheap.
Please, I'm not looking for opinions about the wisdom of having selected this particular kit to begin with. What I'm hoping is that some of you can bring your technical expertise to this and help me figure out what's going on. Does this business of the DAC voltage being too high and saturating the input stage makes sense to you? What do you think it's something else?
Many thanks, in advance!
Follow Ups:
Hi, Folks,
I haven't posted to this thread in a very long time. Thought I'd update it now.
To make a VERY long story short, after hours of working long distance with Brian Smith of ANK trying to troubleshoot the amp, I ended up shipping the amp to Digitalpete in Florida. Pete Fulton builds (and services) a number of Audio Note Kits products. His work is gorgeous and you can order a number of ANK products (including the Kit 1) prebuilt by him through the ANK web site.
In the end, the problem was that the two output transformers had somehow become magnetized. Thus, the amp wasn't putting out anything close to full power. Pete has replaced the two OP TX's and reports that the amp sounds wonderful now. It's on its way back to me and I should have it in a couple of days. Considering how amazing it sounded in many ways before the fix, I can't wait to hear what it sounds like functioning properly!
Brian and Pete were champs through this whole process. They've never seen a set of faulty output TX's like these and are sending them back to the factory to see what went wrong. I'll report back when I have had a chance to listen to the repaired unit. Anyone really interested in the full saga can check out the thread below:
I currently use Reference 3A De Capo BE speakers and previously used the original model of the De Capos (before the "i" model). I've driven both sets of speakers with Coincident Frankenstein 300B monoblock amps and have never experienced clipping, even when turning the volume up to thunderous levels to see if I could make them clip.
The difference may be in the tubes I've used: Emission Labs 300B XLS tubes and Pvane 300Bs. These are "super-300Bs" that put out more like 10 watts instead of 6-7 watts. 10 watts definitely does the job - I now also have a 10 watt David Berning amp and it can make the doors rattle on their hinges without clipping.
So I wonder if your amp can handle these super-tubes and whether a tube change might solve your problem. It's certainly less expensive than buying new speakers or a high quality DAC with a volume control. And even if it doesn't solve the problem, these are terrific sounding tubes that you wouldn't regret having.
Bob Olson,
Thanks for those thoughts. I'd never heard of those "super 300B's" and wonder if they'd work properly in my amp. I'll do some research. thanks for the tip.
I am deeply appreciative of all the thoughtful help that you have given me in this thread. Brian and I are now convinced that this really is about a speaker mismatch. On most music, both analog and digital, the amp sounds fabulous. All of the things you would expect from a great 300 B SET amp – purity of tone, great clarity, gobs of "air" and holographic presentation to die for. I think it's just coincidence that the music that has been causing the amp to run out of steam with the De Capo's is on CD – I don't think it's a digital front-end problem at all. Some of the deep synthesized base and talking about is probably down in "pipe organ" territory. If I play even that music at lower than room-energizing levels, I'm fine, there is no distortion. It's only when I tried to get the volume knob up around 11 o'clock or so that things really start to distort and, again, only on those tracks with very deep, synthesized low and instrumentation.
So, I'm wondering: what speakers would you look at to match with this wonderful amp? I'm eager to hear your thoughts!
With a $2,000 budget, look to used ALTEC, an A7-800, with a partial horn load of the 15 inch, can be cool, or, maybe consider a point source 604.
IMHO, 94 dB is the minimum for tube amps of highest sound quality ( read : 2A3 and Type 45, two stage, direct coupled ) and 98 dB and higher really allows you to play the game well. Small simple amps, big speakers.
Jeff Medwin
I would be looking for something from Tekton, Sonist, Decware, Omega, DeVore.
I've had Klipsch and although they played plenty loud I did not like them.
I've had Tekton Lores and they played well in a small room with a 3-watt 2A3 SET, so depending on your room they might do well. And Tekton makes several different varieties.
I still own Tekton Katz Meow (8" Fostex + Bullet tweeter) and they play very nicely with the SET. Although not as much bass as Lores, in the small room they're in they are perfect.
I've heard Sonist at shows driven by several watts and they sounded very nice.
I've owned Zu Omen, liked the Lores better (by a lot, actually).
Whetstone Audio in Austin carries Devores. The 0/93's and 0/96s are beautiful but pricey. He has a demo pair: "DeVore Fidelity Gibbon 88 in Mahogany Retail $5800 Demos $3595"
Hey, Sebrof my friend! :-)
Thanks for the list... that's exactly what I was looking for.
I would have a budget of whatever my De Capo BE's would fetch... let's say $2000, give or take.
The Lores are very intriguing because they are so well priced and he even gives you a 60 day trial period.
Thanks for the feedback about Zu. They seem to be a pretty polarizing "image" brand and I'm not that interested.
Devore is probably wonderful but out of my price league.
I'd love to hear more about Omega. I know that single driver speaks have their lovers and detractors, but the detractors tend to make a lot of noise online so I'm not so sure.
I'd never heard of Sonist but their web site is very intriguing and I'll hit them up for some info.
Thanks!! And if you PM me I'll tell you a story about Whetstone. :-)
I'm going to say the AN K second hand - the AN K/LX at around $2500 and no they don't need to go in a corner. AN and corners is somewhat overblown - in ideal circumstances the speakers should go in a corner but the biggest selling Audio Note dealer in the world has two demonstration rooms in the heart of one of the most expensive real-estate centers in the world (Hong Kong) and in neither room do they place the speakers in a corner - or even near a wall. The best I have ever heard them sound - and the best sound from a hi-fi system from anyone at any price has been from an AN E in a corner - but what is also true is the worst sound I have heard the AN E has been from a corner. Depends on the gear and the corner.
A more free standing position has generally been solidly good or better. And the amps are designed with these speaker designs in mind. Audio Note claims they are mirror imaged to the speakers which probably means the frequency response/damping factors etc are specifically made for the speakers measured response.
But IMO you should just absolutely NOT buy speakers unheard - you just can't do it because You know I have been on these forums since 1998 or so and before that read tons of magazines about whatever utterly great speaker that was out there. I can safely say that over half the recommended speakers in Stereophile and more than half in TAS I wouldn't touch with a barge pole. And half is a hugely conservative estimate. Chances are if it has a ribbon or any metal driver it won't be something I would want to own.
It may be something I think sounds good mind you and something I could recommend but own? Probably not. And some of these are beloved by many who think there is no comparison and might hate and all paper drivers.
Just be sure that if you have to buy unheard you get a trial or the speaker holds enough value to be sold later for most of what you paid.
The K with the 8 watt meishu.
Richard,
I know you know what you're talking about when it comes to AN, so that being the case, I guess I should keep an eye out for AN speakers used. I can't remember the last time I saw one come up on the used market, but I'll keep my eyes open.
I think that the idea of a speaker really designed with SET in mind makes great sense. Even on a computer, you can tell in that video that there's an ease to the way the music flows out of those speakers that must have to do with headroom and a good, synergistic match.
Cheers!
For an 8 watt amp I would say that 94db + is on order unless you don't listen so loud but it seems you do or if you have a small room. Odeon Rigoletto would work and the Odeon Tosca S just might work (its only a db or so more sensitive than the Ref3as).
You need 92 dB+ high-efficiency which requires subwoofers for that low bass you want. Those sub woofers, to play well at high levels w/o massive distortion (see your own post above ;-} )need Warp 9 amplifiers.
Look up Duke's Jazz Modules and Swarm on High-Efficiency Asylum or go over to Audio Roundtable Pi Speakers. Three Pis might work w/o subs.
At the request of the Moderators,
This space has been deleted
Great combination which of course got gone like everything else I've built ;-}
JBL 2226 with Altec 806/811 combo and a quasi-3rd order Butterworth crossover at 1200 Hz; about 97dB and played the Organ Symphony LOUD!
I look at the book-matched Fiddleback Anegre and wonder where I found the time!
At the request of the Moderators,
This space has been deleted
Rebbi ;
I started a thread , a while back , asking that same question .
"What high efficiency speakers sound like reference 3a's".
All of the suggestions were in the 5 figure price bracket . Out of my ball park !
Thank you for being brave enough to take on this adventure . I was really wanting you to succeed !
The only other thing that I would try , on my Di Capo's , would be an 845 SET . I remain hesitant as the heat could be a bit much in the central Florida summers .
Please keep us apprised of how this turns out for you .
Good Luck
saki70
Parallel 300b works very well and doesn't run out of steam with my Master Control MMCs.
I have the JJ 322, which makes an honest 15-20 watts. The Wyetech Sapphire monos might be a nice choice as well. The JJ doesn't get as hot as big 845 or 211 amp and makes similar power.
Oh it works great with my L'integrales and my Odeon horns as well! A really great sounding amp.
Hi all, I used to own a pair of De Capo's that were built around the year 2000, before the BE model. I tried to get them to work with about 5 watts of single ended power. As long as I was listening to simple non- complex music it worked fine, but when I would put something on that was more complex like classical music it would fall apart!
I tried two different SET amps, and both would run out of steam when pushed. I really wanted to keep my amps so I looked for different speakers. The first pair I tried were Sonist Concerto 2's and these were just the ticket! I sold my De Capo's and did not miss them one bit, but probably would have liked them much better if I had about 30 watts or so, but like I said I wanted to keep my amps(Decware).
Since then I have upgraded to the Sonist Concerto 4's and getting great sound with my 5 watts.( better bass extension.
If you have a chance, check em out!
Tish
I will parrot what a couple of other inmates have already said and share a recent experience with you. My tech and I just finished the first iteration of a pair of 300B amps with a single driver stage and some rare Tango interstage and output iron that I was able to acquire. We were both excited to hear the amps and hooked them up to his pair of Reference 3A De Capo speakers. While these are great speakers and supposedly SE friendly, the 300's just could not provide the umph to get them going, even with very simple acoustic music. After I overcame the initial disappointment, I pulled myself together and took them home and hooked them up to my app. 100db Altecs and Edgarhorns. Frankly, it would be impossible to believe they were the same amps and the impact of efficient speakers. It was truly night and day. The nuances were there, the volume was there, the vocals were buttery smooth, and the midrange was utterly breathtaking. If you are able to do so, I suggest that you mate your amps with more efficient speakers and give them a listen. I am not trying to rain on anyone's parade; I just want to share my experience under similar circumstances.
Edits: 02/05/15 02/05/15 02/05/15
clelow:
No you are not raining on my parade at all. In fact, it's great to have confirmation of my experience with the De Capo's and SET. Thank you so much!
Here's what I've learned. Reference 3A claims that the De Capo's are an easy load and 92 db efficient. Years ago, on the non BE model, JA of Stereophile measured them at just under 92 db. But if you do some googling you will be able to find the latest measurements of the Canadian National Research Council which come up with a different set of figures. They show that, generally speaking, the speaker is more of a 6 ohm rather than an 8 ohm load. Furthermore, they measure its average sensitivity at just shy of 87 dB. In fact, it is really only 92 dB throughout a rather narrow frequency band of 1-2 kHz!
So yes, I have loved my De Capo's, but if I want to continue with SET in this particular 300 B amp, then I think I do need to look for a more efficient speaker!
I've just noticed the following:
"I should also note that it is using the stock tubes, except for having substituted a 274 B which Brian of Audio Note Kits sent me instead of the stock rectifier tube."
I believe we274b rated 150ma with capacitor input = 75 ma / side. In the kit1: SRPP ~10ma, 6sn7 ~7ma. With 880ohm cathode bias 300b will have Ia over 58ma for sure.
That has nothing to do with the CD playback issue, just something to know about.
I had this Kit1 for awhile and can recall that the 300b tubes are run very hot ie: 80ma-90ma. Also, I thought the main power trans was a bit undersized and ran extremely hot. In the amp I had, the oil caps in the driver stage failed a couple of times, as did the 100V rated electrolytic bypass cap in the 300b cathode.
I had similar distortion issue with distortion when playing peak female voice notes from a high output tubed AN DAC, and after going through a lot of trouble-shooting with the amp I found out the culprit was a leaking coupling cap on the DAC output.
Hope this helps.
Would also add that the kit1 just won't have the juice to drive small bookshelf speakers (even with the big C-core AN OPTs, which were what I had), unless the OP only listen to girl & guitar music. I dont think the OP should pursue any further, simply the speaker-amp will not work in long run.
It does not exactly explain the difference you hear between CD and LP, but my de Capo i's simply did not play well with 300B's (highly modded Welborne Laurel Ultimates). Lack of dynamic range and authority. They play much more happily with PP EL34's. Try amp with more efficient speakers if you can burrow some. May not be the amp and sources at all. May be bad synergy.
I never could get the amp and speakers to sing together. I got rid of both and am much happier with my Audio Note Kit-4 and Audio Note E Spx speakers. They really work well. Maybe it's a mismatch.
This just doesn't appear to be an amplifier-speaker mismatch. Rebbi has clearly stated the sound is excellent with his analog source, so there's something amiss with the digital source. I believe this will be sorted out. Others have driven these speakers very successfully with the Coincident Dynamo, sn 8 watt el34 SEP amplifier.The AN Kit 300b should just as capable if not more so.
I did note Rebbi that in your original Agon post, Philojet noted that he didn't get good synergy with his 8 Watt Audionote amp and the Decapos either. Just as Cpwill mentioned, it might not be a good match. Hopefully though, it'll turn out to be something else and an easy fix. Good luck in getting it all sorted out.
Do you have 5V across the cathode resistor at the first triode? Play a 60Hz tone through your DAC and measure the AC voltage at the output, just to be sure it's 2.2V.
A 60Hz test tone peaking (normalized) at a digital zero, right?
That' how I tested my CD player. The manual says 2 volts RMS and that's what it measures.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
I don't think signal level from the digital source is the problem.... (But I could be wrong.)
"Subterranean" bass takes up gobs of power..... It could be a simple case of the deep bass clipping an 8-watt 300B amp driving 92 dB efficient speakers. Especially where the bass response of the speakers isn't extended. (If I recall, the Reference 3A De Capo is a smallish speaker.)
Since you did build the amp, the only other thing I can think of is maybe the bias is off..... That will cause an SET amp to clip (saturate or cut off) at lower power levels.... And deep bass will bring out the problem.
Todd,
Thanks a lot for the post. As I mentioned earlier, Brian doesn't think it's the DAC output, but some problem with the build; perhaps I mis-wired something or I have a bad tube on the driver board. We're working together to systematically troubleshoot this and I'll report back when we find the problem. What's odd is that bass-heavy material creates no distortion on the analog side. It sounds fantastic, in fact! But the fact that the DAC is putting out 2.2 V and the phono preamp only 550mV may mean something here. As a last resort, I may take the amp to a local and very good stereo repair shop (the guy specializes in vintage equipment and knows tubes) and enlist his troubleshooting help. Brian has assured me that he's committed to making me totally happy, which means something for sure.
The digital and analog output levels are not the same measurement. The analog voltage is derived from the cartridge output, rated in mV at 5cm/sec. That is the nominal VU peak (short-term average). Actual instantaneous peaks can be much higher, with good carts able to handle as much as 50cm/sec; the old-school working assumption was that peaks are 14dB above VU peaks.
Digital is always rated by full-scale peak, and corresponds to the analog level plus 14dB (5 times the voltage).
Note that these days, when extravagantly powerful compressors are widely used, that assumption of 14dB headroom is ... optimistic? ... yeah, that's a nicer-sounding word.
Paul,
Thanks for the post.
So, in layman's terms, are you suggesting that an 8.5 watt 300B SET amp simply can't handle certain kinds of music in the digital realm?
If that's not what you mean, can you clarify your remark in non-technical terms?
Thanks again.
"So, in layman's terms, are you suggesting that an 8.5 watt 300B SET amp simply can't handle certain kinds of music in the digital realm?"
I'm not sure if an 8-watt 300B SET amp will have enough power to drive 92-dB efficient speakers to satisfying volumes with music containing lot of deep bass energy. (The same amp might be just fine w deep bass with > 98 dB efficient speakers.)
By the way, I think Paul's suggestion of using a high-pass filter at the input is a good idea..... If the speaker doesn't have extended bass response, you won't miss much down there.
Sorry for the lack of clarity. I was only addressing the concern about the apparent difference in levels - with well-recorded material it should be small in practice.
I don't see enough information in this thread yet to know what the problem is with the digital material. A number of good possibilities have been suggested, and I think the "overloaded first stage" theory is unlikely if that stage is operating correctly - which you are already engaged in checking, I think.
If it is very deep bass overloading, either deliberately encoded in the digital or caused by an noise/instability/error in the digital side, then a simple high-pass filter at the amp input would be a possible test.
Lower the input by a factor of 5 or so and see if you are ok then prior to going into the input tube.
See if you can borrow/use a computer with a small outboard USB dac to test this. That's what i did recently, as my CDP also has a lot of gain. AN is also known for making high gain 300B amps (their standard version; they also sell low gain models). I know AN(UK) is no longer affiliated with AN Kits, but the driver circuit is the same as (or close to) in their Meishu integrated.
Observe, before you think. Think before you open your yap. Act on the basis of experience.
Try an in-line attenuator in-between the DAC output & the SET amp input.
How about, just for testing purposes, try an iPod or smart phone or computer with the volume maxed (turn down the preamp volume of course).
If you get distortion at max volume out of the device, and when you decrease the volume of the device and increase the volume of the preamp you get no distortion, you may at least have your answer.
If you never get distortion with the device then you'll still need to find a variable out CD player or dac.
Just a thought.
My first thought when he said it was an old DAC was to wonder if there is any DC offset on the output of the DAC, maybe the prior amp had a blocking cap that solved the issue. Anyway, worth measuring, it would certianly change the bias on the input stage.
Tre,
Just to be sure I understand, are you suggesting that the problem is the power amp section of the integrated amplifier not being able to put out enough power? Again, he didn't seem to think that was the case. I just wish I had a CD player or a DAC with a adjustable and a lot output section to test that theory.
OK, now that I looked at the schematic, the input stage comes before the volume control.
It is possible that the DAC is placing too much signal of the grid of the 6sn7 clipping it.
A "...CD player or a DAC with a adjustable [output]..." is a great idea.
Do you know the rated output voltage for the DAC and the phono pre?
I'll take a look at the bias point for the 6sn7 and that should tell me how much signal voltage it would take to clip it.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
I wonder why they put the level control there?
That seems odd to me as well.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
As luck would have it, I already did my research on this. The DAC outputs 2.2 V. With my cartridge, the phono stage should be putting out about 550 mV.
2.2vac rms is 3.1 volts peak.
The 6sn7 has 4.75 volts bias. The 6sn7, in circuit, has a gain of about 15.35
3.1 times 15.25 is a peak voltage at the plate of 47.5 volts.
The 6sn7, in that circuit with those currents and voltages [7ma., 175 volts plate, 27333 ohms plate load] should output well beyond that without trouble.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Tre,
Thank you very, very much for taking the time to look all that up.
I have subsequently been in touch with Brian and he, like you, thinks that the 2.2 V output of the DAC should not be presenting any problem. At this point he thinks it is some kind of problem with the driver stage. Perhaps I reversed some resistor values or it may be that one of the three tubes mounted on the driver board are not good. In any event, he is going to help me troubleshoot this so I'm feeling better about where this is going. I will let you folks know what I find out, just for educational purposes. :-)
Thanks again!
"He is suggesting that the DAC is putting out too high a voltage ..."
Can't you just turn the volume control down?
If the power amp is clipping because it's getting too much audio signal, the only answer is to attenuate the source signal. Unless you wanted to re-design the power amp circuit for less gain but then there might not be enough for the phono pre output.
Do you have anyway to test the amp for output power?
If the amp is making the rated output power before clipping then it's probably not the problem and you're just playing it too hard.
My 2 cents.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
No, it may not help. AN kit 1 volume is after the first amplification stage 6SN7. If this one is clipping due to very high input signal, volume won’t help. But I doubt it is the case.
I thing it just because with 91dB (real sensitivity of DeCapo) kitOne is just clipping with loud bass. I doubt that this amplifier can have more then 3-4w output at 20-30 Hz. Also 91bB is at 1KHz, at lower frequencies sensitivity in nowhere near that.
What you can try to do is to disconnect volume control from the capacitor from 6SN7 anode and send DAC signal direct to the volume control.
But again, it probably won’t help. Also, you can't compare analogue playback with the DAC, there are no that low frequency components with that amplitude on the LP
Edits: 01/28/15 01/28/15 01/28/15
"AN kit 1 volume is after the first amplification stage 6SN7"Yes, I saw that after posting.
Please see my newer post above in this thread.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 01/28/15
Speaker sensitivity can also be an issue, picking up all the bad stuff and transmitting it at high volumes with great detail.
Observe, before you think. Think before you open your yap. Act on the basis of experience.
We're pretty sure speaker sensitivity isn't the culprit here because the Kit 1 is driving the De Capo's just fine with the phono side of things -- Bottlehead Seduction, specifically.
Post a Followup:
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: