[Mister Pig]

Recently acquired a pair of Sachiko double horn cabinets, the plans of the speaker can be found at the frugal audio site. The speaker is originally designed for the Fostex FE206E, however I located a pair of Fostex 208 Sigma, and the designer of the cabinet has indicated that this cabinet will work for the Sigmas.

The plan is to find another SET amplifier to use with the Sachiko, as I no longer have the Electra-Print 300DRD amps that I had awhile ago. I do have a couple of modest amps here, one a 2A3 SET, and another a 6L6 SEP. Both sound decent on these speakers, but not really a long term match.

One afternoon, I decided to see what my Jeff Rowland Consummate pre-amp and Model 5 amplifier could do on these speakers. I have often said that these pieces have many tube like qualities, and are extremely nice sounding SS electronics.

OK I got them hooked up, these pieces stay idling in my rack, so they are well into their warm up curve. Played a few well known tracks, the sound was interesting, but not what I was looking for. I swapped out the Monarchy OCC speaker wire I was using, and dropped in some silver ribbon speaker wire, this was the wrong choice! Ugh. I suffered for awhile, but ultimately out came the silver. then I inserted a run of Analysis Plus Oval 9 speaker wire, and things got interesting. The tonal balance is quite nice, lots of low level detail, very good imaging, nice dynamic contrasts.

Really there is very little to fault to this pairing. The big class AB amplifier is producing some fine sound on these speakers. It doesn't have quite the presence and liquidity of the best SET amps, but it is on par or better than an inexpensive SET. I suspect a traditional tube push-pull is going to be hard pressed to surpass it. I suspect that a bit more fine tuning with interconnects and power cords can close the gap in terms of midrange performance. I currently have two sets of silver ribbon interconnects in the system, and the power cords are a copper/silver hybrid. So there may still be some incremental improvements that can be found.

The only issue I do have is volume control. The Consummate uses a relay/resistor volume control, although the steps are not terribly large. However the amp is 150 wpc, and when combined with high efficiency speakers it becomes difficult to fine tune volume. Possibly a pair of in line attenuators will alleviate this issue. Thats the next step in this journey.

The lesson I learned is that high efficiency speakers do not absolutely require SET or even low powered amps to sound good. Yes I love the sound of a good 2A3 or 300B, or a well designed chip amp. But it appears that a well designed Class AB solid state amp can bring the goods too.

Regards
Mister Pig

[ohenry]

I have experienced good results with high-powered SS amps.  The Pass X150 and little Horn Shoppe Horns is a dynamite combo.

You just have to be careful about the powering up and down sequence.  Turn the amp on last, and turn the amp off first... or you can fry those little Fostex drivers in a flash.   

[Mister Pig]

[quote author=ohenry link=topic=78395.msg743202#msg743202
You just have to be careful about the powering up and down sequence.  Turn the amp on last, and turn the amp off first... or you can fry those little Fostex drivers in a flash.   
[/quote]

Turn off? Afraid I don't turn off my SS gear. The Rowland gets a bit warm at idle, but its not one of those power hungry Class A amps that suck the juice.

I have found that the Rowland improves over time if left on. While this is purely subjective, it doesn't seem to stabilize for a week. After that its sonic character is rock steady.

Regards
Mister Pig

[roscoeiii]

I imagine that the efficiency of the speakers means that you are running your SS AB in Class A mode, even if it is not heavily biased towards Class A.

On the issue of volume control, I found the same problem due to my overly powerful preamp (yes, preamp. It's a Musical Fidelity kW into the 10W FirstWatt F1 feeding DIY Audio Nirvana 12" stamped frame speakers). Goldenjacks attenuators did the trick. Great customer service too.

[Bemopti123]

I have done my own experiment with this idea. 

I had a SET/7-8 watt per channel powered into a pair of Bob Brines BR-20 speakers matted with a Fostex Alnico magnet FH-96 tweeters.  The speaker has controls for tweeter attenuation as well as variable BSC control.

To this, I replaced it with a SS battery preamp, into a rebuilt HK-740 Twin Transformer receiver circa 1978, removed the jumpers and added the preamp in. 

The receiver easily produced a really beefy 40 watts, that feels more like 100 watts.

The results are a very fast and quite smooth presentation, as these FE-206 8" drivers can soak up power well enough.

SS or even high powered SS is wrongly portrayed as a non synergistic match by common popular knowledge, but depending of the type and quality of SS/high powered amplification, it can give you something that common SETs will lack...jump fact and speed. 

Remember the Listener magazine and how they matted a 47 Lab gaincard with a pair of Lowther Medallion horns? 

[neobop]

You could try a passive attenuator in place of the preamp. That way you could avoid the additional degradation of in-line attenuators. A preamp contributes 10 to 20 dB of gain (typically) that you don't need in this situation.

There's no such thing as a preamp that improves the sound. If it seems to, then its either a coloration that works with the rest of the system or the gain it provides. A passive with one input and a quality attenuator (like a Goldpoint) will provide the least amount of degradation possible. IMO even the selector switch mangles the sound. Just get an attenuator that matches or is slightly less then the input impedance of your amp.

It really doesn't matter how much additional power the amp can develop (I like those Rowlands) the gain is fixed. Luckily, it's enough with efficient spks that you don't need the additional gain of the pre. The best preamp is no preamp.

[lcrim]

I use a Dayens Ampino SS integrated w/ Louis' Omega Compact Hemps.  The Ampino is Class AB w/ 25 watts @ 8 ohms & 40 watts @ 4 ohms and the sound quality is really special.  This has a passive attenuator, not a preamp w/gain.  The bloom is somewhat tube like but clarity and lowlevel detail coupled w/ more realistic dynamics and superb treble make for pleasurable listening.
The only drawback to me, is that I can't concentrate on reading when its on as the music draws me in.

[Bob_Brines]

I run my ~92dB/w/m speakers off of a 100w/ch SS amp most of the time. Occasionally I will use a ~6w/ch T-amp or a 9w/ch PP tube amp. The SS amp has far and away better dynamics because it has real head room. The T-amp has a clearer sound, and the tubes are more mellow. Each is different. Good/bad is in the ears of the beholder.

Bob

[roscoeiii]

There's no such thing as a preamp that improves the sound.

I don't want to open up a huge can o passive vs. active preamp worms, because that could take the thread pretty off topic. I'll just say that this is not my experience, despite running very efficient speakers.

We each listen for different things. The detail of the passive I had was nice, and I had to spend a good deal more to get an active pre that matched that level of detail. But the active preamps I have had did a much better job with the drive and oomph present in certain music.

And I'm not alone here. From a different thread:

I didn't think a preamp could or would improve things...after playing around with some active preamps, I determined that my prior thinking was wrong!!

Others also mention the positive effects of actives on dynamics and liveliness.

Ultimately it depends on what you are listening for in your system. And the type of music will also play a part. The more impact (think rock and bombastic orchestral stuff) the more I found an active pre benefited my system.

Don't want to hijack the thread with this debate, but wanted to point out my experience and others' suggests that active pres can be preferable for some people, due to their listening priorities. 

[neobop]

Well, the topic is high efficiency spks and large solid state amp, so it's on topic. But I don't want to get into a debate either. I use both active and passive preamps. Whether or not you can lose the active part depends on your situation. There is a big difference between 89dB spks and 100dB spks. Also, room size and deadness makes a dramatic difference. Also the source(s) involved. It's pretty tough to drive 2 amps with a passive, because it's your source driving the passive and cables and amps.

Blanket statements on the viability of a passive are absurd because every situation is different. I can drive my system to full dynamics with my DA converter or tuner, but not usually my phono pre. As a matter of fact, if I use an active preamp with CD or tuner it has too much gain.

Maybe I didn't express myself well, but what I meant was a preamp can't improve on the sound quality from the standpoint of the purity of the signal. Every switch, relay, or device the signal goes through, degrades. Dynamics and punch not withstanding, it's the quality of the signal, itself I was talking about. It's the old straight wire and gain approach.

[Triode Pete]

...and not all SET's and even SS (solid sand) amplifiers are made the same...including all pre-amps & Speakers as well...

I've found that the quality & design of the build is far more important than the quality of parts used...

For High Efficiency Speakers, it is a kind reminder that the First Watt (or first 100 milliwatts) are most important... for the majority of SS amps, this extremely low power region is definitely not their strong point...

My $0.02,
Pete

[Mister Pig]

...and not all SET's and even SS (solid sand) amplifiers are made the same...including all pre-amps & Speakers as well...

I've found that the quality & design of the build is far more important than the quality of parts used...

For High Efficiency Speakers, it is a kind reminder that the First Watt (or first 100 milliwatts) are most important... for the majority of SS amps, this extremely low power region is definitely not their strong point...

My $0.02,
Pete

You know regarding this point:

for the majority of SS amps, this extremely low power region is definitely not their strong point...

For the SET crowd, this is a commonly held belief, and one that gets repeated almost as a mantra.

But I am not sure this really is the case. After all most SS, especially Class AB amps are going to run in Class A for their first few watts, and until pushed hard will they revert to Class AB. So in essence they are going to perform their best at a lower power level.

Secondly, its not like the distortion levels, noise floor, dampening factor, frequency response, or any other factor is going to improve as it is driven harder. The technical side...ie measurements....are still going to be at their best. Only when driven to their limits will the amplifiers performance start to fall off.

So why would allowing a SS amplifier cruise just above idle cause it to sound worse? I don't know of any explanation for this. If anyone can explain it, it sure would be interesting to know.

Regards
Mister Pig

[roscoeiii]

Yes, I am in agreement Mr. Pig.

I'd like to hear any impressions of why one might prefer a low power Class A amp only amp vs an AB amp that is running in Class A exclusively due to the sensitivity of the speakers. Or why there might be no significant difference between the 2.

-Roscoe

[JoshK]

If you are really interested, look up crossover distortion and summaries of tests done on the audibility of crossover distortion.  In short, it is much more audible than THD for instance even in much smaller quantities, but typically more so with high efficiency speakers.

Therefore, the rule of thumb that hi-eff + class A amps (or SET amps) isn't out of thin air, there is actually evidence to support this idea.  However, it isn't that simple, like most things audio, and one can design Class A/B amps that has near immeasurable crossover distortion, but it isn't easy and not that often done.

[JLM]

Just as a public service reminder, if worried about turn off/on transients you're advised to leave your system off (or unplug the speakers) in case of unforeseen power losses.

[Mister Pig]

If you are really interested, look up crossover distortion and summaries of tests done on the audibility of crossover distortion.  In short, it is much more audible than THD for instance even in much smaller quantities, but typically more so with high efficiency speakers.

Therefore, the rule of thumb that hi-eff + class A amps (or SET amps) isn't out of thin air, there is actually evidence to support this idea.  However, it isn't that simple, like most things audio, and one can design Class A/B amps that has near immeasurable crossover distortion, but it isn't easy and not that often done.

Would you happen to have any links to the articles that reference the audibility of crossover distortion?

The articles I have read show an extremely even wave form with a Class AB amplifier operating properly. Actually, the only way they could show the notch at the zero point was by significantly decreasing the bias voltage. The page that described this the best was this one:

http://www.aikenamps.com/CrossoverDistortion.htm

From what I see the phenomenon of crossover distortion does not appear to be significant, especially when compared to other challenges that are found in amplifier design.

Or it may be that the Rowland Model 5 I am using is a successful implementation of what SS amps are capable of. While not the most expensive amp out there, and fairly simple when compared to a current production flag ship amplifier....it was considered to be towards the top of the class for SS technology.

I plan on listening to a good SET amp on the Sachiko sometime this year. However, if I can get things optimized, I suspect the Rowland may be a benchmark of what the amplifier candidates are going to need to surpass.

Regards
Mister Pig

[JackD201]

I  hear good Hi-eff + Hi-power SS all the time. It's the staple in movie theaters and clubs everywhere in the world. Problem isn't the pairing of the two, it's in how well implemented the pairing is.

[Triode Pete]

I  hear good Hi-eff + Hi-power SS all the time. It's the staple in movie theaters and clubs everywhere in the world. Problem isn't the pairing of the two, it's in how well implemented the pairing is.

Yeah...what are the SPL's in the movie theatre for hi-fi effects? What is the SPL in a club playing "Boom, Boom, Boom"? Never in a million years would you have a SET amp in either scenario. For music, yes sweet music, for high efficient speakers (>100 dB/w/ 1 m) in a home environment, the most "natural" & most simple linear amplifying device ever made by man is the triode tube...true in the 1920's & true today...The exceptional linearity of Class A triodes removes the need for feedback, sidestepping problems with phase margin and stability with complex and nonlinear loads, which pretty much describes all loudspeakers. In particular, complex back-EMF currents from the drivers stop at the plates of the output tubes, instead of being mixed at the summing node with the incoming signal. This avoids load-dependent distortion terms being generated in the feedback circuit. So if the theory of triodes having large amounts of local feedback is correct, they'd have less distortion at low orders of harmonic distortion than high power pentodes, but more distortion at higher orders. This is exactly the opposite of what measurements disclose. Measurements going back as far Harry F. Olson show triodes not only have less distortion overall, but most significantly, have far less upper-harmonic distortion. In fact, vanishing amounts of upper-harmonic distortion is the distinctive hallmark of triodes, compared to all other amplifying devices, including high power solid state amplifiers! Also, low power SET amps with tube rectifiers (like the 5AR4) have the absence of rectifier switching noise. The noisiest circuits of all are solid-state bridges driving large values of electrolytic capacitors, as found in almost all transistor gear. In terms of ragged waveforms, solid-state diodes are the worst, followed by Schottky diodes and HEXFRED's, followed by conventional tube rectifiers...I could go on & on...but I rather not bore you... I just like to keep things very simple (KISS Principle)...like SET amps..

"If you got ears, you gotta listen"... Don Van Vliet, aka Captain Beefheart

Peace,
Pete

[JoshK]

Would you happen to have any links to the articles that reference the audibility of crossover distortion?

I'll have to do some digging.  I've seen it referenced, but didn't read it myself.

P.S.  I agree with what others have said.  If your speakers are hi-eff and your amp has a relatively high bias, you are running in class A with headroom.  You probably haven't heard the sound of the B class cause you probably never left A.

[JackD201]

No need to convince much less preach to me Pete I've got 2a3s and 300Bs. Also, all my SS and hybrid amps are single ended, zero global negative feedback just like my DHT SETs.

All I'm saying is that you CAN get good sound out of Hi-Eff and SS as others here have also experienced. I'm just not one to use "Best" loosely much less impose what I do consider "Best" on others.

I do have ears and I do listen. That was a cheap shot and you know it. Peace to you too.

"Never in a million years would you have a SET amp in either scenario." - Just one more thing. Get your history straight. Those NOS RCAs and WEs likely came from cinemas. Ben Hur, Gone with the Wind, Wizard of Oz WERE slamming happy viewers with SETS. SETS also powered Jazz club vocals from the 20s up until PP and later SS came into the picture.