[capwkidd]

I am use to listening to my NuForce amps, and they are great on the bottom but, they are just not SET's in the mid/top.... Who makes the best compromise between theses two sounds?

[Jon L]

Well, great SET's with stiff power supplies CAN have great bass, BUT it usually requires speakers with pretty specialized bass tuning, i.e. these speakers would not have great bass with usual solid state amps..

Personally, I actively biamp my custom speakers, running SET from 140Hz and up and solid state below. 

[zybar]

I am use to listening to my NuForce amps, and they are great on the bottom but, they are just not SET's in the mid/top.... Who makes the best compromise between theses two sounds?

It isn't a SET, but to my ears, Atma-Sphere amps provide exactly what you are looking for.

George

[JLM]

What's the rest of your system like?  Just having a good tubed pre-amp can help.

How much juice do you need and how much do you want to spend?

Lots of nice 30 - 40 wpc push-pull EL34/KT88 amps around for about $1,000 USD.

The $2500 Decware Torii Mk III (25 wpc) looks interesting.

Towards the upper ends, peak at the Vacuum Tube Logic 222W monoblocks ($4,200/pair) or if 100 wpc is OK, the Manley Snapper monoblocks ($4,250/pair).

If you're still after a bit of solid state, look at the 200 watt Vincent SP-T800 Hybrid Power Amp ($4500/pair).

(At this price I recommend monoblocks.)

[Gopher]

My previous SET did a fine job with bass, but it was a larger SET (845 monos) mated with very efficient (101db), crossover-less speakers.  It wasn't bass to write home about, but a complete sound--more complete then SETs (2a3, 45) I've owned in the past or SEPs for the matter.

The Atma Zybar mentioned will give very solid bass, but the OTL sound is not for everyone and is not a similar sound to SET.

I own am listening to the Decware Torii 3 as I type this and it is quite the amp with earth shattering bass, but as JLM aludes to, it is an el34 push/pull.  That said, it's got harmonic density and textures that exceed any SET I've owned (Fi, Wright, Shuguang, etc.).  Its a really good PP.

[richidoo]

Heard these at Capital Audio festival past weekend driving large Klipsch horn clones and small MTM ported speakers. Both had excellent bass control and impact, unbelievable actually, for a 20W PP 300B. I think they outslam my own Manley 300B SEPPs. Like any amplifier, the quality and capacity of the power supply, and good speaker synergy is what makes great bass. These have separate huge external power supplies.  I spent time on Saturday night chatting up the designer of these at the show. I would not hestitate to buy from him (Gary,) he's been in the business for 30 years, a real electrical engineer, wise beyond his years about audio technology and life in general, and a hell of a nice guy. Worth a call just for the conversation!



http://www.borderpatrol.net/

[ultrafi]

To me, this thread is at best misleading and at worse, just plain wrong.

Here's what's actually happening.  First, in order for the small signal model for any amplification stage to hold, or for the assumptions therein to be valid, the impedance of the power supply must be much much smaller (generally a factor of 10) than the stage it is supplying.  Now, let's look at a single ended (SE) output stage.  Generally, one picks the a tube with the lowest plate resistance (rp) that one can find.

The small signal model demonstrates that, in essence, the load is in series with rp - forming a voltage divider.  Maximum power transfer occurs when Rl and rp are equal; but, then distortion rises too much.  So, a ratio of 2.5-3.5 is generally chosen.  This is another discussion however.

Now, look at say a 300B, for example.  The rp is around 800 ohms.  So, the power supply impedance must be 800/10 or 80 ohms or less.  There ain't no way most 300B SE amps have a power supply Z less than this.  First off the secondary of the power transformer is typically on the order of at least 50 ohms and more often 100-150 ohms.  Now, tube rectifiers also add substantial impedance.  Say, best case, in the case of a monoblock, a voltage drop of 15 volts.  15/100mA is 150 ohms.  Now you have the impednace of the choke at low frequency.  Clearly this is more then than 80.

Now, stiff you say.  Well, you can make it (the power supply) well regulated - add big caps or use some sort of regulator; but, to most everyones ears this makes things sound worse sonically.  The amplifier stage is a dynamic thing, which in part means the small signal model falls apart, in some sense, but, when a transit occurs, the cap or the regulator must meet the necessary demand and then recover from having done so.  This is where big caps or regs (stiff) falls apart.

What one wants is a low impedance (relative to it's supplying), high rev (excellent recovery under dynamic music demands) power supply!

Audio amplifiers aren't really amplifiers; but, impedance matchers.

I think this thread is pointing towards some instances of what I lay out above but crediting the wrong mechanisms for having the desired benefits.

I routinely build SE amps that have bass people have never heard before and is irrespective of power level.

[rollo]

  Single ended amps can and have wonderfull bass. I have found them to be truer to tone and harmonic structure than most SS amps. Just a different presentation. Running 211 SET and have plenty of good ol bass, focused, tunefull and balls to the floor.


charles
SMA

[Wind Chaser]

My current 300b amp has deeper, meatier, more authoritative and refined bass than the last few SS amps that have passed through my hands.

[JoshK]

A lot also depends on your speaker's impedance/phase curves.  Lots of ported bass speakers are poor matches for SET amps. 

[Steve]

To be honest, nope. And for several reasons (triodes and UL). But we can get closer. And I use to design SET amps.

1) I have heard dozens, if not hundreds, of SET amps
and not one has used the proper size coupling capacitors.
So a lack of bass before we even hit the output stage.
Increase the size of the coupling cap from what the schematic shows.
If it motorboats, then not worth working on.

(As a side note, because almost every design uses far too small of coupling caps, customers purchase the most inaccurate caps (bass heavy) in order to "compensate" for the lack of bass. Luckily  manufacturers can still special order some good caps.)

2) The power supply high voltage cap is nearly always
too small, thus a portion of the bass signal that should be
across the OPT primary, is across the power supply cap.
So lack of bass.
Increase the size of the cap if possible.

3) RL (OPT) to Rp is nearly always a problem; bass shy.
Check OPT frequency response specs. Not much one
can do to improve the bass spec.

4) Damping factor is quite poor. Attempt to lower
the output Z of the amp by raising the primary to secondary
impedance ratio.

One other point is the woofer with a Q of over .7-.8. This
artificially increases the bass (think bass bloat in normal amp terms), and also causes problems above bass frequencies.
As the saying goes, there is no free lunch.

But the above suggestions will improve the low frequency bass response.

Cheers.

[yo2tup]

My 845 SET amp has great bass

[Steve]

My 845 SET amp has great bass

I would be curious to know what is the frequency response, -1db, at one watt and full power?

Is it parafeed operated, which helps with bass response?

Thanks Yo2.

[Wind Chaser]

The only thing that matters to me is what my ears hear.  Technical explanations to the contrary - no matter how logical and persuasive - will compensate or prove satisfying to my listening experience. 

[yo2tup]

I would be curious to know what is the frequency response, -1db, at one watt and full power?

Is it parafeed operated, which helps with bass response?

Thanks Yo2.

no idea!  it's a viva solista mkIII

[Steve]

The only thing that matters to me is what my ears hear.  Technical explanations to the contrary - no matter how logical and persuasive - will compensate or prove satisfying to my listening experience.

Hi Wind,

Of course it is difficult to relate in absolute terms how accurate one's system is. Are you saying that if you found a component or system that is more satisfying then you would not purchase it (assuming you could afford it)?

I mean if the system is obviously lacking in bass (unless the room is distorting/bloating the bass) then it cannot be improved upon and be more satisfying?

Unfortunately I see there are no specs listed for your SET amp.
However I will continue looking.

Cheers.

[FullRangeMan]

As suggested by previous posters, a SET amp with big bass have to use a big triode output tube, as 211, 845, 805 etc...
The more affordable and friendly amp I know is this 805 SET with 38/40W, I like much this amp as it is monoblock and had a pre-amp to be drive direct by a CD player, all for a low price.
http://www.pacificvalve.us/MD3008A.html
If you can afford some spare Shuguang 805 and 300B tubes it is a great option.


P.S.> Some owners of 6C33 SET amps say this tube also have a great bass with sensitive speakers ( + 96dB).

[Steve]

As suggested by previous posters, a SET amp with big bass have to use a big triode output tube, as 211, 845, 805 etc...
The more affordable and friendly amp I know is this 805 SET with 38/40W, I like much this amp as it is monoblock and had a pre-amp to be drive direct by a CD player, all for a low price.
http://www.pacificvalve.us/MD3008A.html
If you can afford some spare Shuguang 805 and 300B tubes it is a great option.

I am wondering how raising the output power betters the frequency response, especially at the low end? I suppose the high frequency response suffers due to a large OPT with increased losses, which would give the appearance of more bass. And we still have the problems of the four points that I mentioned in a previous post.

Yes, the 6C33 could easily have more bass due to the very low Rp of the tube vs the 845. Points 1,2,4 may become more prominent compared to point 3, depending upon the OPT construction. High frequency response could also be much greater with the 6C33.

Cheers.

ps. Almost forgot, there is also a phenom called synthetic bass, which is not real bass.

[FullRangeMan]

I am wondering how raising the output power betters the frequency response, especially at the low end? I suppose the high frequency response suffers due to a large OPT with increased losses, which would give the appearance of more bass. And we still have the problems of the four points that I mentioned in a previous post.

Cheers.

I can not say anything that makes sense about it, as Iam unlettered in electronics.

In fact, I and some local friends tube lovers are wondering how much hours life this 805 tube can have in this Ming-Da amp, with a high power of 40W??
 I thanks in advance any input or opinion...

[Steve]

I can not say anything that makes sense about it, as Iam unlettered in electronics.

In fact, I and some local friends tube lovers are wondering how much hours life this 805 tube can have in this Ming-Da amp, with a high power of 40W??
 I thanks in advance any input or opinion...

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.