[SET Man]

Hey!

    SET amp with great bass? Well, mostly this will all depend with what speaker you are going to use with it.

    I think most people missed one important thing about using SET is that you will need a good speaker that would match well with the SET amp. And this is were the complaint started most of the time. Well, speaker that work great with your Nuforce will most likely will not be a good match with SET amp.

   Of course there are other factors too. The power output of the SET amp, tube used. And more importantly the design and built of the SET. A SET done right can be costly... beefy power supply and quality output transformers and etc.

    Anyway, I've been with my SET monoblocks for the past 11.5 years with my DIY 6" Fostex in TQWT loaded cabs and I've never feel that I've have been lacking in the bass. OK, I can't do very deep bass from something like soundtrack from the Batman movie and etc. But with real music the bass sounds fine to me... natural, nicely textured, and natural decay.

    BTW... if you ever go to a show and there is an Audio Note UK room. Make sure you stop by. With Audio Note speaker they are freakin' great and can really rock out. If I ever leave the single driver and go 2 way speaker route I will put their speaker on my list for sure.... well maybe the kit version because I don't think I can afford their finished line.

Take care,
Buddy

[TONEPUB]

You are absolutely right, the amp/speaker combination is critical.  I had great bass with all the SET amps I used, just needed a good speaker match.  OTL's are kind of similar in that regard.

[Steve]

It is hard to quantify what someone is saying since
what is one's man's good enough may not be accurate,
because of the points below, or room acoustics adding.
But SETs are known for "midrange magic" and at least some
of the perception is due to weak bass.

As such there are a couple of points to consider.

1) The OPT themselves have limited low bass response. All one
has to do is look at the specs to see the OPTs are not flat to
20hz. This is a given. And high Rp tubes are worse than low Rp
tubes. (Rp is the plate resistance of the tube.)

2) The coupling capacitors are way too small for accurate,
flat bass response. Interstage transformers also have losses.

3) In order for the speakers to have enough low bass
response for said amps, the speaker Q has to be well
above .7-.8, sometimes 1.5. This results in flabby/bloated bass, which we all know is what tube amps are known for. It also gives the impression of more bass. The high Q also influences the entire range of the driver affected. Ok, three points. 

4) Synthetic bass is also a problem. According to the
RCA Radiotron Designers Handbook, page 616, 1960:

(A) When two or  more input frequencies are applied to a non-linear amplifier the output will include sum and difference frequencies located about each of the higher input frequencies. ... Even if the lowest frequency is very much attenuated by the amplifier, the sum and difference frequencies tend to create the acoustical impression of bass. With more than two input frequencies the effect is even greater, so that fairly high distortion has the effect of apparently accentuating the bass.

(B) Owing to the peculiar properties of the ear, a single tone with harmonics may be amplified, the fundamental frequency may be completely suppressed, and yet the listener hears the missing fundamental.

These two effects assist in producing "synthetic bass"- when the natural bass is weak or entirely lacking. It should be emphasized that this is not the same as true bass, and does not constitute fidelity."

So although the bass may appear enough, there are variables that affect the accuracy of the bass and higher.

I don't know if this has been addressed directly to me or not. If not, please accept my apology.

BTW... if you ever go to a show and there is an Audio Note UK room. Make sure you stop by. With Audio Note speaker they are freakin' great and can really rock out. If I ever leave the single driver and go 2 way speaker route I will put their speaker on my list for sure.... 

If you brought it up to me, I have been to CES/The Show and heard all the SETs there, hundreds overall over the years. Anyway, I found virtually all lacking sufficiently that of the dozen or more times I visited each of the SET rooms over the days; virtually no one was there. Maybe two at the most in one room. But Atmasphere and other rooms were filled, standing room only. By the way, I exhibited at the AKfest in Detroit 2009.   
 
I found what is stated on various forums has been quite different than what occurred in reality, and how others felt. So I feel I am not alone in my assessment.

Cheers and have a great week.

[SET Man]

Hey!

   Steve, this is the second post from you on this thread and it all about technical again. Not many of us are as technically inclined as you are so thanks for the infos. I'm not very tech inclined myself so I can't really get into it.

   I'm sure that amps that you are selling measured waaaaaay better than my SET monoblocks But fortunately or unfortunately, depend on how you see it, I don't listen with scope. I listen with my ears.

   I think most SET users are music lover rather than tech junkie and listen to the sound with ears first than look at the measurement later.  Personally I find my SET based system sound reminded me of the real thing. Of course it can't do everything. But there is something very delicate about it. I got a lots of good feedbacks from fellow audio friends on my system also.

   SET based system is very finicky and getting it right can be hard and take time. But it does have it positive sides and if that happen to be your preference than it is worth to try build system around it.

   It is not for everyone but I can say there are happy SET users out there, and I'm one of them. Well, like life... audio is a compromise. You can't have everything. You should what matter and make it your priority.

    So, to those newbie who haven't heard SET. Keep open minded and give it a listen when you have a chance to do so.... preferably ones that done and set up right. You might find your calling with it.

   BTW.... Steve I didn't bring that Audio Note thing up to you. I don't know how you perceived it that way. 

Take care,
Buddy

   

[Steve]

Steve, this is the second post from you on this thread and it all about technical again. Not many of us are as technically inclined as you are so thanks for the infos. I'm not very tech inclined myself so I can't really get into it...... 

   BTW.... Steve I didn't bring that Audio Note thing up to you. I don't know how you perceived it that way. 

Take care,
Buddy

 

Hi Buddy,

Thanks for your views and I will attempt to reply in order, but I may go by another way. I responded in general, not you in particular. The Audio Note is not worth commenting on. As mentioned above, did not know if you were personally addressing to me or not.

  I'm sure that amps that you are selling measured waaaaaay better than my SET monoblocks But fortunately or unfortunately, depend on how you see it, I don't listen with scope. I listen with my ears.

I think most SET users are music lover rather than tech junkie and listen to the sound with ears first than look at the measurement later.  Personally I find my SET based system sound reminded me of the real thing. Of course it can't do everything. But there is something very delicate about it. I got a lots of good feedbacks from fellow audio friends on my system also.

I appreciate your explanation, but I must correct you on some false assumptions.

First, I am not just a "tech junkie". No harm taken or meant though, Buddy.

Secondly, many don't realize that it took approximately 3 1/2 years of sophicated/proprietary listening tests to get the sound right on my preamp even though the specs varied only slightly, and are quite excellent. Same way with my amps. 
I have performed years of careful listening testing that others either cannot or do not perform. So listening testing is quite important to me. 

So, to those newbie who haven't heard SET. Keep open minded and give it a listen when you have a chance to do so.... preferably ones that done and set up right. You might find your calling with it.

The problem is if one looks at all the schematics, one continually sees the same or similar problems with each design. Sorry, but small caps are small caps, and OPTs are OPTs.

SET based system is very finicky and getting it right can be hard and take time. But it does have it positive sides and if that happen to be your preference than it is worth to try build system around it.

 It is not for everyone but I can say there are happy SET users out there, and I'm one of them. Well, like life... audio is a compromise. You can't have everything. You should what matter and make it your priority.

I am happy you, and others, love your systems. I have no wish to degrade your system. I am simply responding to the question initially asked, and produced facts, not only technical, but also through years of sophicated listening tests.

Lastly, I know it is difficult to convey how good a system is via posting. I hope you can appreciated the years of devoted service and testing that has been performed.

The best to you Buddy. 

[SET Man]

Hey!

  Steve, you WIN!  I'm not an amp designer so I don't know what I'm talking or hearing. So, I am not going to get into this anymore.

  Have a good on Steve.

Take care,
Buddy

[Steve]

Hey!

  Steve, you WIN!  I'm not an amp designer so I don't know what I'm talking or hearing. So, I am not going to get into this anymore.

  Have a good on Steve.

Take care,
Buddy

I am not the winner. The viewers are the winners.

Take care my friend.

[FullRangeMan]

Haven't checked out the amp page, but the 805 tube is high Mu, grid current is required for much power output. Tube is normally operated class B, zero or near zero bias; much like the 811 tube.

It can be operated in Class A2 mode, which means the driver must have low output Z, have some power output capability as grid current is drawn.

Efficiency is the key to obtaining higher power.

Cheers.

Maybe this Ming-Da 805SET run in Class A2 on the 300B to 805.

About the gain, I noted 845 & GM70 are low MU, and the 211 and 805 are hi Mu.
So I wonder If these hi Mu big triodes are better or easiest to drive than the low gain (845 or GTM70)??

[Steve]

Maybe this Ming-Da 805SET run in Class A2 on the 300B to 805.

About the gain, I noted 845 & GM70 are low MU, and the 211 and 805 are hi Mu.
So I wonder If these hi Mu big triodes are better or easiest to drive than the low gain (845 or GTM70)??

Hi Gustavo,

Yes, the Ming-Da is most probably driven A2 unless they are doing some exotic thing.

Yep, I have not looked in a long time but I would not doubt your facts. To add to your listing, the 811 is high Mu while a brother, the 812 is low Mu.

You question is interesting. The high Mu triode requires low distortion power to drive the output tube. The low Mu triode requires a huge driving voltage, but little power per se. Interesting choice if one wishes to use them.

The 805 states aproximately 6 watts drive, but class A2 is probably less. However it needs to be low distortion.

Luckily the driver stage is low impedance as the Mu of the 805 is approximately 50 - 60. Given that the grid to plate capacitance is 6.0pf; means we have approximately a 400pf (.0004uf) of Miller capacitance that the driver sees.

The 845 tube has Miller capacitance of approximately 70pf. But the 845 takes approximately 400 volts peak to peak to drive it.

Cheers.

[FullRangeMan]

STEVE: very thanks for your valuable help I did unknow this detail.



OBS:> My interest is to know the low gain GM70.

[Steve]

STEVE: very thanks for your valuable help I did unknow this detail.

Your welcome.

GM70?

http://www.shinjo.info/frank/sheets/018/g/GM70.pdf

http://www.jacmusic.com/nos/GM70/index.htm

Only thing I would mention is concerning the 20 volt filament. If run DC as the author suggests, the grid to cathode/filament bias will vary by 20 volts. Long term, this will cause uneven cathode "wear". I would place a switch in the filament circuit so once in a while, reverse the filament voltage, to more evenly "wear" the cathode. Just a thought.

Cheers Gustavo

[Quiet Earth]

I think we each have a personal definition of what great bass is. We also have our own expectations of how much bass we should hear when we press the play button. I would like to add something to the discussion that hasn't been mentioned yet.

Some of my recordings have scary-deep, fast and powerful bass sounds with killer perceived dynamic range. These recordings might use synthesized instruments, acoustic instruments, or a combination of both. When I play these recordings I am amazed that such powerful music can emanate from my eight watt amplifiers and primitive looking speakers. To live with this every day is to believe it. I know that my system is capable of making "great bass" in the context of a musical event.

By comparison, some of my recordings have average to meager bass sounds, with not so good perceived dynamic range, and sort of an in-the-box recorded sound quality. Here's the rub. When I play these recordings, should I be disappointed because I don't get the same spectacular results that I get with those other recordings? Is my amplifier doing something wrong because it can't make every recording sound as spectacular as a group of disks that I have assigned as a reference? Or, is the amplifier actually doing something right because it doesn't make everything sound the same?

On our list of compromises to make, one of them might be to adjust our expectations of what the playback system is supposed to do. Or, maybe what it isn't supposed to do. I don't know where to take it from here. It's kind of too heavy for me to continue . . . .


Just for what it's worth, and I mean this with no malice or bad mojo intended, I seem to be breaking a lot of rules and getting very pleasing results. I even get "great bass", especially when the recording calls for it.

Here is the list of sins that I commit every day.

1. Small coupling caps (I guess  ). Only 0.47uF in the amp and a meager 0.22uF in the dac between the two 12AU7s. Not sure what is in the phono stage but it's probably too small.
2. Small power supply high voltage capacitor (I guess  ), with two of them in series reducing capacitance even further. The rectifier cap is also miniscule in C value because I have the nerve to use a....
3. Tube rectifier. (Please don't go changing the size of your tube rectifier supply cap just because you learned that you will get better bass. First take the time to learn if greater capacitance is acceptable for your specific circuit.)
4. Poor damping factor because there is no measurement to prove otherwise.
5. Transformer in the output of the amplifier. Also in the dac, transformers coupling from the A/D chip to the first tube, and transformers coupling the second tube. A transformer volume control too, and passive to boot! (I'd like to upgrade that someday . . .) Anyway, all of those transformers must add up to the equivalent of a sloppy high pass filter. So where's does all of that bass come from? 
6. Ported speakers. I didn't know that ported speakers and single ended tube amps are normally a bad match until reading this thread. Interesting.
7. Small gauge speaker cable.
8. Unorthodox  speaker placement.
9. Last but not least, components made by the company that everyone loves to hate. I could care less. I bought it all to make myself happy and happy I am. If and when I hear something better (that I can afford) I will gladly sell it all and move on. I'm sure there's better gear out there and I just haven't heard it yet. I'm cool with that.

 

[Steve]

I think we each have a personal definition of what great bass is. We also have our own expectations of how much bass we should hear when we press the play button. I would like to add something to the discussion that hasn't been mentioned yet.

Some of my recordings have scary-deep, fast and powerful bass sounds with killer perceived dynamic range. These recordings might use synthesized instruments, acoustic instruments, or a combination of both. When I play these recordings I am amazed that such powerful music can emanate from my eight watt amplifiers and primitive looking speakers. To live with this every day is to believe it. I know that my system is capable of making "great bass" in the context of a musical event.

By comparison, some of my recordings have average to meager bass sounds, with not so good perceived dynamic range, and sort of an in-the-box recorded sound quality. Here's the rub. When I play these recordings, should I be disappointed because I don't get the same spectacular results that I get with those other recordings? Is my amplifier doing something wrong because it can't make every recording sound as spectacular as a group of disks that I have assigned as a reference? Or, is the amplifier actually doing something right because it doesn't make everything sound the same?

On our list of compromises to make, one of them might be to adjust our expectations of what the playback system is supposed to do. Or, maybe what it isn't supposed to do. I don't know where to take it from here. It's kind of too heavy for me to continue . . . .


Just for what it's worth, and I mean this with no malice or bad mojo intended, I seem to be breaking a lot of rules and getting very pleasing results. I even get "great bass", especially when the recording calls for it.

Here is the list of sins that I commit every day.

1. Small coupling caps (I guess  ). Only 0.47uF in the amp and a meager 0.22uF in the dac between the two 12AU7s. Not sure what is in the phono stage but it's probably too small.
2. Small power supply high voltage capacitor (I guess  ), with two of them in series reducing capacitance even further. The rectifier cap is also miniscule in C value because I have the nerve to use a....
3. Tube rectifier. (Please don't go changing the size of your tube rectifier supply cap just because you learned that you will get better bass. First take the time to learn if greater capacitance is acceptable for your specific circuit.)
4. Poor damping factor because there is no measurement to prove otherwise.
5. Transformer in the output of the amplifier. Also in the dac, transformers coupling from the A/D chip to the first tube, and transformers coupling the second tube. A transformer volume control too, and passive to boot! (I'd like to upgrade that someday . . .) Anyway, all of those transformers must add up to the equivalent of a sloppy high pass filter. So where's does all of that bass come from? 
6. Ported speakers. I didn't know that ported speakers and single ended tube amps are normally a bad match until reading this thread. Interesting.
7. Small gauge speaker cable.
8. Unorthodox  speaker placement.
9. Last but not least, components made by the company that everyone loves to hate. I could care less. I bought it all to make myself happy and happy I am. If and when I hear something better (that I can afford) I will gladly sell it all and move on. I'm sure there's better gear out there and I just haven't heard it yet. I'm cool with that.

 

First, I thought that presenting listening tested information would be helpful. I am sure many viewers welcome such information since it might help them in the future by asking some key questions such as the value of coupling capacitors, or how many transformers/chokes are used in the signal path. (Also see my previous posts.)

Thanks for a wealth of information although it would be appreciated to know the load resistors for the .22 and .47 uf coupling caps.

I believe you mentioned 4 transformers. Each transformer has at least 1db loss at 20hz. This means approximately a 4db loss at 20hz, about 1.4 db loss at 40hz, and approximately .5db loss at 80hz. This is voltage loss in DB.

Power wise we are talking 2db loss at 20hz. Does not seem much except 3db power loss is half your power output.

As far as coupling capacitors, .22 and .47, .68uf are so far below what is necessary for accurate bass. What happened is that some "gurus" used their "scientific" formula for/at 20hz to say what was the necessary value capacitor for flat bass response to 20hz. Unfortunately, they never performed any listening testing to verify it. They also never tested other parts for sonic accuracy.

Another question is are the subjective coupling capacitor tests accurate? If the capacitor(s) under test are too small in value, the answer is no, because the accurate capacitor will sound too thin, which it should. Afterall, too small a cap is being tested.

Instead, they will choose the fuller sounding cap as sounding more natural. So what brand(s) flourish? The ones who sell the fuller, less accurate capacitor(s). That is not to say that some caps are actually thin sounding because of their construction/terminations etc.

Another problem is that the fuller sounding small caps not only "fill out" the bass, but also "fill out" the midrange and highs as well. But there is a sonic difference between an accurate, proper size coupling capacitor and a smaller fuller sounding capacitor. The accuracy of the entire audio band is compromised/manipulated by the smaller, fuller, inaccurate sounding capacitor.

As far as your "mediocre" recordings, they may actually be very nice earth, while the 'bassier' recordings may actually have even more bass output.

I am hoping that real science by actual listening tests wins out over  the science of assumptions. Especially the misguided "science" equation of calculating the value of a cap for 20hz operation.

Cheers.

[FullRangeMan]

Your welcome.

GM70?

http://www.shinjo.info/frank/sheets/018/g/GM70.pdf

http://www.jacmusic.com/nos/GM70/index.htm

Only thing I would mention is concerning the 20 volt filament. If run DC as the author suggests, the grid to cathode/filament bias will vary by 20 volts. Long term, this will cause uneven cathode "wear". I would place a switch in the filament circuit so once in a while, reverse the filament voltage, to more evenly "wear" the cathode. Just a thought.

Cheers Gustavo

Great tip Steve, thankyou again, Iam always surprised how many details can exist in a seemingly simple SET amp.
JacMusic site is promissing a GM70 Sakuma SET for years, but so far nothing...

What you mention refers to all big Triodes?? or just to the GM70 which have a longer cathode than the USA big triodes??

The 211,845,805 triodes have a filament wire like this ^^ in M shape and the GM70 filament is longer ^^^.
More details in the image below:

[Niteshade]

There is something that should be known about bandwidth and power output. The more power you have, the better a wide bandwidth can be presented, providing the speaker system can accept it. You can have exceptional bass response with a few watts, however, you will not get too much volume out of it before the poor amp runs out of gas.

Energy has to be conserved with low power amps and that is why many of the early small tube amps (AKA: Magnavox, Emerson, Packard Bell, etc..) had reduced bandwidths. They were more concerned about improving the delivery quality within a narrower bandwidth since they knew you can only stretch, say, 4 watts/channel only so far. Typical bandwidth was around 80hz to 15K, not bad! It sounded pretty good too and had plenty of warmth, though resolution was sacrificed.

Would it be worth it to, say, use transformers rated 10-30K on a 5 watt amp? Not in my opinion. It is done frequently, but there are better ways of doing things. Save that iron for something with more horsepower. 

The large RF/AFtriodes are being mentioned- now THAT'S a worthy kind of tube to mate a decent, high quality single ended OPT with. You do bump into the laws of physics again, however: Upper end frequency response is often slightly (or more than slightly) rolled off. This will provide a somewhat warm (boosted mids) audio playback while highs may be smooth. Reason: RF tubes are very high impedance, around 10K. Inductors by nature attenuate high frequencies. A transformer is a very close cousin to an inductor. As their impedance increases, so does their ability to cut off high frequencies.

[Steve]

The large RF/AFtriodes are being mentioned- You do bump into the laws of physics again, however: Upper end frequency response is often slightly (or more than slightly) rolled off. This will provide a somewhat warm (boosted mids) audio playback while highs may be smooth. Reason: RF tubes are very high impedance, around 10K. 

Good points. With a high primary to secondary ratio (20k to 8 ohms for example, high turns ratio), the high frequencies tend to go out the window due to leakage inductance problems. Providing several taps causes even more problems.

And of course working with higher plate voltages and peak signal voltages requires more/better insulation between primary and secondary, again increasing leakage reactance and lowering high frequency response.

Wording it another way, with high Rp tubes, the primary inductance of the OPT needs to be extremely high for flat 20hz response. A conflict arises in that flattening the low bass response (more iron/more turns) causes a loss in high frequency response. Special interweaving is necessary but only goes so far. Core materials, winding techniques all make a difference.

There was one transformer that had a bandwidth of 1mhz if I remember correctly. It was X-ray and three different transformers were found inside, one for lows, xovered to mid/highs, xovered to extraordinary highs. Of course the problems is matching the three. Interesting idea though, and very expensive.


---------

Hi Gustavo,

Well the 20 volts is high for directly heated triodes. Low Mu triodes, not so much of a problem, but high Mu triodes, yes more of a problem.

Cheers.

[FullRangeMan]

Thanks Steve, okay so far with the GM70, as it is low mu=6 to 8.
Thanks alot,

[HT cOz]

Seems like a never ending set of tradeoffs. A little ot but have you guys seen the new Hypex Ncore announcements? www.hypex.nl/index.php?option=com_content&view=article&id=89
  Their creator is very excited about them and he doesn't seem like the type to talk something up.

[TONEPUB]

well, you can always cross that SET over at about 80hz and use a powered sub!

[bunky]

Good points. With a high primary to secondary ratio (20k to 8 ohms for example, high turns ratio), the high frequencies tend to go out the window due to leakage inductance problems. Providing several taps causes even more problems.

And of course working with higher plate voltages and peak signal voltages requires more/better insulation between primary and secondary, again increasing leakage reactance and lowering high frequency response.

Wording it another way, with high Rp tubes, the primary inductance of the OPT needs to be extremely high for flat 20hz response. A conflict arises in that flattening the low bass response (more iron/more turns) causes a loss in high frequency response. Special interweaving is necessary but only goes so far. Core materials, winding techniques all make a difference.

There was one transformer that had a bandwidth of 1mhz if I remember correctly. It was X-ray and three different transformers were found inside, one for lows, xovered to mid/highs, xovered to extraordinary highs. Of course the problems is matching the three. Interesting idea though, and very expensive.


---------

Hi Gustavo,

Well the 20 volts is high for directly heated triodes. Low Mu triodes, not so much of a problem, but high Mu triodes, yes more of a problem.

Cheers.

hey Steve, was the transformer that was x-rayed designed by Vladimir Lamm ?