[hebrer]

What is your opinion on matching single driver speakers (in my case Fostex FE127eN with 91 dB sensitivity) with

A) a SET tube amp (I never had one and hear the second harmonic magic is something that must be heard)
or
B) a digital amp (e.g. Virtue ONE using Tripath chip) in compination with a single ended triode pre-amp (or possibly just a tube stage output in CD player)
?

I currently use push-pull tube amp with 4 EL84 tubes used as triodes and cannot decide which of the options above would most likely bring an improvement...

Thanks for sharing your experience or thoughts on this.

Peter

[jrebman]

What needs improvement?  It's all a compromise and nobody can tell you what you will like better.  Personally, even with a good tube preamp, I found that I just cannot live with any sort of tripath or digital amp.  They are fun and somewhat alluring at first, but then their annoying qualities snowball.  That's me though and others love them.

Also, not all SETs or SEPs are created equal and having been through more than my share of them, it's nearly impossible to predict how a given amp will sound with your speakers, in your room, anhd with your music.

That said, a pentode in triode mode is nothing like a proper triode.  For a decent to really good SEP amp with el884s, and enough power for your speakers (probably) try something like the Almarro A205 Mk. II.  EL84s are some sweet sounding tubes, but to me they sound far better in Pentode and a properly executed UL mode than triode strapped.  In triode, even very good ones sound bloated, slow and rolled off on the top end.

-- Jim

[Niteshade]

Well said!

Feedback and driver circuits make more of a delivery quality difference than the tube used or even the iron. I just hooked up a Magnavox push-pull 6V6 amp with small iron and couldn't believe the sound quality! The bass didn't go as deep nor the highs as crisp as better amps- but they used what they had to its full potential and it sounded MUCH better than one would have imagined even possible. The lesson is: That the magic lies in the circuit, not so much the topology. But keep in mid that different topologies do have their advantages (push-pull, SE, SEP, etc..). For example, push-pull & SEP designs tend to sound richer, more bold than single ended types. Having enough power for a balanced delivery during demanding passages is important. The Maganvox was tonally perfectly balanced for the hardware it had to contend with. Balanced tone,resolution, speed and good sound staging at your desired listening volume have to be thought of while shopping.

As was stated earlier, what's wrong with your present setup? El84's can provide excellent performance in push-pull circuits.

Also, not all SETs or SEPs are created equal and having been through more than my share of them, it's nearly impossible to predict how a given amp will sound with your speakers, in your room, anhd with your music.
-- Jim

[hebrer]

Thanks Jim and Niteshade,
the information is really useful.

The trouble is that I do most of my listening at low volume and my current set-up (2x7W Yarland FV-34C III tube amp) does not sound "effortless" or detailed enough - I feel like I am missing the resolution that I can hear at higher volumes.

I wonder if the way to correct this is to aim for "higher-quality" first watt or rather to use more power...

A SET amp of 2 watts for channel (e.g. Zen triode amp) may not do the job with a speaker of only  91 dB sensitivity...

Getting a full-bodied detailed sound with good soundstage and imaging at low volume is what I am after.

[Niteshade]

I doubt you'll want a single ended amp then. Push-pull and single ended parallel (SEP) can provide enough wattage to be more engaging at low volumes or any volume, actually. I wouldn't go below 15 watts/channel for that sensitivity.

Suggestions:

1] Push-pull EL84 or 6V6

2]SEP 6L6/EL34/6550

3]The tripath idea is worth a try as long as it's 30 watts or more per channel. From what I have read, the smaller ones can get grainy sounding if pushed.

NOTE: I never liked triode wired pentodes. They're "wimpy" to me. This mode restricts the tubes' performance. They run out of gas much quicker than tetrode-wired pentodes. Some people love triode mode due to some of it's virtues, but I doubt triode mode amps would suit your needs.

[anubisgrau]

it all depends how do you hear the music.
i've had altmann BYOB and t-amp and neither could come to a magic of a good SET amp. even first watt F3 with 10w sounded way better in terms of proper tone and enjoyment (harmonic qualities). i don't know what is your budget but there's a plenty of good choices. even a PP EL84 would be a great choice.

[richidoo]

I use 300B SEPP in parallel triode mode with good results on 91dB single drivers. 
Single driver speakers like current source amps, like Pass F1.
http://www.passdiy.com/pdf/cs-amps-speakers.pdf

[hebrer]

Hi Richidoo,
I am glad to read that even with 91dB single drivers, it is possible to get good results with single ended tubes - in parallel mode. I am hoping the harmonic character of the music will be more enjoyable with SET or SEP than PP if the power issue can be resolved.

[jrebman]

Peter,

Part of the problem here is the 5" driver and the laws of physics.  I'd almost say that to do what you want with what you have, some EQ is going to be necessary.  That said, a larger 6 inch driver, and especially one with an alnico magnet will definitely present a fuller musical experience at low levels, and I'd second the idea of something like an SE KT-88or similar larger bottle pentode in single-ended configuration as still a very musical amp but with the ability to deliver some punch in the low end.

Power supplies are also very critical in any single-ended amp and as heretical as it may seem, a switching power supply with super low impedance is going to give you a greater sense of fullness at lower levels.  There aren't a whole lot of SE amps out there with switching supplies, but one is the Miniwatt S1, which bottom end performance and dynamics are quite good for it's stated 2.5watt power (though I suspect it is somewhat less than that).  They are said to be coming out with some 300b monoblocks in the future, but when that will be, and what they will actually be like, is anybody's guess at this point.

The tubelab simpleSE with 6550s or kt-88s and good iron could be another good possibility.  I know soebody who may be selling one, but I'd have to check with him first to see if he's still wanting to do that.  If he is, it's a really top notch one with custom electraprint iron all the way around, and lots of premium parts, and built by a guy whose craftsmanship is great.  No affiliation to the seller except that he's another virtual audio friend in another part of the country.

-- Jim

[JLM]

The higher efficiency Fostex drivers can easily sound thin, so some tube warmth is welcomed.  But a better solution would be a better cabinet to start with.

"Second order harmonics" is a form of distortion that is less objectionable then odd order harmonics, but it is still distortion.  If you want to get all mushy, go rent a romantic comedy.  Otherwise try to avoid coloration/distortion.

Some audiophiles, as hobbists, like excess complication and layer the tubes to the point its hard to know what the music was supposed to sound like.  I'm not opposed to tubes, but the very best comes in both tube and various solid state variants.

[jrebman]

JLM,

He did not say what cabinets he has --- how do you have any idea that that is where the problem lies?  Also, are you trying to say that you have a purist system with no distortions?  These of course, are rhetorical questions and intended to remind you to stay on topic and not use every thread as an excuse to post one or more of your mantras.

Thank you, The Facilitator

[hebrer]

I am using the Metronome design - see http://www.frugel-horn.com/metronome.html
for the modified 4.5" Fostex FE127eN (http://www.planet10-hifi.com/FE12xeN.html).

I believe very similar driver is used by Ed Schilling (http://www.thehornshoppe.com) in a horn design and he says on his website his speakers work fine with SET amps of 3+Watts.

Now it may be that full-bodied sound at low volume cannot be expected from this size of driver but I am getting incredibly good midrange (compared to my previous Focal JM Lab speakers) and I like the speakers (my first audio diy project) and coherence.

Judging my previous posts, I am uncertain with a fullranger with rolled off highs and less strong bass the SET design would bring much extra compared to EL84 push-pull design.

Anyway, there is still so much for me to understand about tube amplification and the right matching with speakers that I need to do more learning. Thanks for suggestions given above.

[hebrer]

Correction: ...judging by previous posts...

[jrebman]

Peter,

The Metronomes are certainly voluminous enough for decent bass out of the FE-127s, but again, not all 3 or 5 or whatever watt SETs are equal.  Iron, topology, power supply and implementation all figure in the equation.  Push-pull amps should be able to deliver more bottom end wallop, but if the amp was not originally designed for triode mode, that could be one place to look.

Again, I hate to say it but EQ may be your best, most cost-effective solution in this situation.  After that, larger drivers with more powerful magnets and higher sensitivity, and/or looking into what mode the amp was designed for and put it back in that condition.

Hope this helps somewhat.

-- Jim

[hebrer]

Jim,
yes, it does help. Having no crossover in the speakers at the moment, EQ might be the answer, even if that is a totally new area for me. I have not done much tuning of the speakers in terms of damping so more experimenting might also improve the sound.
P.

[chrisby]

I am using the Metronome design - see http://www.frugel-horn.com/metronome.html
for the modified 4.5" Fostex FE127eN (http://www.planet10-hifi.com/FE12xeN.html).

I believe very similar driver is used by Ed Schilling (http://www.thehornshoppe.com) in a horn design and he says on his website his speakers work fine with SET amps of 3+Watts.

the first part of that statement, and its proximity to the prior sentence could get you into some sheep-dip on certain forums - but the following simple corrections should suffice:
- the driver Ed has been using for the past several years is the FE126E, which performs quite differently in the Horns than the FE127E in any appropriate design 
- he has little patience for driver modifications such as the En-thing
- Horn owners have been happy with anywhere from 2-3watts of SET (i.e. 2A3, SV83/EL84 etc.) to all sorts of much higher power tube and SS amps.

Now it may be that full-bodied sound at low volume cannot be expected from this size of driver but I am getting incredibly good midrange (compared to my previous Focal JM Lab speakers) and I like the speakers (my first audio diy project) and coherence.

Judging my previous posts, I am uncertain with a fullranger with rolled off highs and less strong bass the SET design would bring much extra compared to EL84 push-pull design.

Anyway, there is still so much for me to understand about tube amplification and the right matching with speakers that I need to do more learning. Thanks for suggestions given above.

There's no doubt that  FR drivers of this size may* have some limitations in terms of max SPLs, bass extension, etc.,  but has Jim has noted, and others will surely add their own votes on the issue, they can deliver a lot of magic.  System synergy is an even more important factor here, and at the end of the day, there's no substitute for your own experience, preference, and tolerance for compromises.

Most of my listening is at moderate to lower levels ( i.e. well under 90dB, and most often below 80db), so high power reserves is not as much of a concern for me.  Neither am I expecting larger than life-size imaging and blow the candles out dynamics - tonality, texture and soundstage dimensionality are my personal goals.   

To that end, I happen to prefer the sound of my FE127E and FE167E  on Bottlehead 2A3 SET or DIY EL84 triode P/P to a much higher powered Jolida EL34 U/L pentode or Kingrex 20 watt Tripath.


* may   as in - depending on your expectations and application, etc

[planet10]

I have a bit of experience with FE127eN

These, in most boxes have a synergy with amplifiers with highish output impedance. The rising impedance of the FE127eN as it approaches HF & LF means that there is a bit more power where it is needed.

Most SETs fall into this category, but as Jim points out, not all SETs can be lumped together as execution makes a huge difference. The primary amplifier i use with my Fonkens is an almost 4 W/channel set of SEP EL84 monobloks that are an RH84 variant. They handily outperform a SET 300B i have here. I'd say the RH84s compare to Chris' 2A3 in a 6 of one, half dozen of another relationship. Chris' Wright Mono 300Bs are a step up (traded for a set of Fonken). The little PP EL84 Class A tridode strapped beast that Chris has is pretty special. Within its modest 3.2 W/chan it gives up a bit of midrange magic to the SETs,  but has bottom end that is unrivalled by few (within its power limits).

My room is fairly big (~250 m^3), and the 4 W amps start to run out of juice when i start pushing things (rarely). The helper woofers XOed at 100 Hz with their own 150W dual mono MOSFET really helps in those situations.

dave

[hebrer]

To get a feeling for the SET sound, I went for an inexpensive experiment.

For $36 + s/h I ordered a SET class A headphone amplifier with 6N11 tube (and no OP amp or IC in the circuit).

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=260503007690&ssPageName=ADME:B:BCA:US:1123#ht_5197wt_1162

Even if powered by 24 V switching PS, the second order harmonics should be there for listening on headphones to get a taste of it, before doing anything with the amp for speakers.

I am also curious what effect this headphone may have as a pre-amp in my system.

Peter

[hebrer]

Another "component" with high value-to-price ratio that I discovered when "processing" the inputs above is the know-how from Jim Smith at www.getbettersound.com

Hopefully this $44.50 investment will bring better results than new equipment.

[pjanda1]

Chris and Dave: wouldn't those Metronomes benefit from some BSC?

I mainly wanted to say that I've spent the last few days listening to a little TA2024 based amp in place of my (not entirely different from Chris's) PP triode wired 6V6 tube amp.  I'd stick with the tubes were I you.  Maybe you'd enjoy some mods (minor or major), but I don't think a digi amp would be a step up.  That isn't to say I don't like and recommend them, but I do not believe they compete with well implemented tubes.

Paul