[anubisgrau]

Hello aa

By the end of February I will take on a delivery of my new speakers which are 114db multihorns - 2x15" active bass in an isobarik chamber with BMS DC driver for 300-25k hz duties in a tractrix horn.

So it's time to think about a proper amplification for these. The manufacturer recommends a highly tweaked gainclone: I've heard it and despite overall excellent impressions I thought it lacks a final touch of "life" that only a great SET can give.

The caveat is that my system is used by my lady too and we also have 3 cats so my attention was caught by the reviews of F3 that it may be a good solution for these who wants SET sound but can't have valves for different reasons.

I am aware that it is often that a product is welcomed as a killer of this and of that, however only time will tell the truth. So my post is addressed to those who have an extensive experience with F3: how does it really behave in a room on a long run. Is it a keeper or its SS nature is still something it can't runaway from.

My listening priorities are an overall sense of "live"-ness, good drive and dynamic capabilities, but also a natural and sweet timbre and tone.

Another option for me would be to mod my current Altmann BYOB which is I'm afraid unsufficient for really outstanding results in its stock form. It took me quite some time to listen to it in a highly revealing system to realize that there is much more to an amp duty than what it delivers.

[jrebman]

I don't know about the F3, but the F1 and F4 run quite hot -- 50 degrees C or more, so don't know if that's a consideration or not.  I believe you can build a lower power version of the F4 that may run a bit cooler, but I may be confusing this with something else.  BTW, the F4 is basically a unity gain (actually very slightly less) current buffer amp, or impedance converting amp, that depends on the linestage for voltage gain.

I'm intrigued enough that I've bought a set of boards and PSU boards for the future -- which you can do through Peter Daniel on the diyaudio forum.  See the classifieds section and the wtb: pc boards for F4 thread.  This amp supposedly combines the best attributes of the previous F series amps.

Or... how abvout a tube cage .

-- Jim

[anubisgrau]

I don't know about the F3, but the F1 and F4 run quite hot -- 50 degrees C or more, so don't know if that's a consideration or not.  I believe you can build a lower power version of the F4 that may run a bit cooler, but I may be confusing this with something else.  BTW, the F4 is basically a unity gain (actually very slightly less) current buffer amp, or impedance converting amp, that depends on the linestage for voltage gain.

I'm intrigued enough that I've bought a set of boards and PSU boards for the future -- which you can do through Peter Daniel on the diyaudio forum.  See the classifieds section and the wtb: pc boards for F4 thread.  This amp supposedly combines the best attributes of the previous F series amps.

Or... how abvout a tube cage .

-- Jim

That's another thought I've had, however I was warned that it's not certain how would F4 behave with a rather complicated filter my horns utilize. For sure a current amp won't work, it needs a standard gain feed to work. The another caveat is that IMHO F4 shifts the responsibility for speakers' drive from a power amp to a pre so it would open another Pandora's box: to find a really outstanding, dead quiet preamp with enough gain. Currently I have EAR 864 which is excellent but I don't know how it would behave in such a scenario, as well as a TVC that would be out of question.

[sts9fan]

The F1-3 are current source amps.  They are generally considered inappropriate for use with passive crossovers.

[anubisgrau]

The F1-3 are current source amps.  They are generally considered inappropriate for use with passive crossovers.

F3 is not a current amp, it's a gain amp (15db gain I think).

[sts9fan]

I was wrong.  The F3 is a voltage source. 

[JoshK]

That's another thought I've had, however I was warned that it's not certain how would F4 behave with a rather complicated filter my horns utilize. For sure a current amp won't work, it needs a standard gain feed to work. The another caveat is that IMHO F4 shifts the responsibility for speakers' drive from a power amp to a pre so it would open another Pandora's box: to find a really outstanding, dead quiet preamp with enough gain. Currently I have EAR 864 which is excellent but I don't know how it would behave in such a scenario, as well as a TVC that would be out of question.

I, personally, think the Aikido amp is just about the perfect gain stage for the F4.  Apparently I am not alone, since many others have already done this.  I ordered some F4 boards to play around with at some point.  6SL7 into 6SN7 yields around 29dbs of gain with low noise (due to noise canceling), low distortion and low output Z. 

Do you have a impedance curve for your drivers with network?  How about phase angle w/ freq?  Those two together should tell you what you need to know about how hard it is to drive for any amp. 

[jrebman]

I too think the Aikido would be a great choice to drive the F4 with.  You could even build as a dual mono and take it another step up.  I believe many folks are using their F4s with multi-way speakers with passive crossovers.  As to how friendly those crossovers are, you'd probably have to weed thrugh the giant thread on diyaudio to find out specific speakers.  I'm quite confident that the ACI Sapphires will be fine with this amp.

-- Jim

[Les Lammers]

Hello aa

By the end of February I will take on a delivery of my new speakers which are 114db multihorns - 2x15" active bass in an isobarik chamber with BMS DC driver for 300-25k hz duties in a tractrix horn.

So it's time to think about a proper amplification for these. The manufacturer recommends a highly tweaked gainclone: I've heard it and despite overall excellent impressions I thought it lacks a final touch of "life" that only a great SET can give.

The caveat is that my system is used by my lady too and we also have 3 cats so my attention was caught by the reviews of F3 that it may be a good solution for these who wants SET sound but can't have valves for different reasons.

I am aware that it is often that a product is welcomed as a killer of this and of that, however only time will tell the truth. So my post is addressed to those who have an extensive experience with F3: how does it really behave in a room on a long run. Is it a keeper or its SS nature is still something it can't runaway from.

My listening priorities are an overall sense of "live"-ness, good drive and dynamic capabilities, but also a natural and sweet timbre and tone.

Another option for me would be to mod my current Altmann BYOB which is I'm afraid unsufficient for really outstanding results in its stock form. It took me quite some time to listen to it in a highly revealing system to realize that there is much more to an amp duty than what it delivers.

I had the F-3 for a while and sold it. *I* never had/found the right preamp for it. *I* did not think it sounded like tubes. Depending on the complexity of your crossover, 10 watts may not be enough even with 114db speakers. I know someone who has $$$ GOTO compression drivers that are 106db and ten watts was not enough. Are these speakers you designed yourself?

[Paul_Bui]

I've been quite happy with a GC amp (AS Patek SE) and a tube pre (SP MPX3) driving a single driver speaker via the BYOB DAC.  I'd check out Decware ZEN 26w Torii mk II (no preamp needed).

Oh, I had an FW F2 for a while and sold it.

[Telstar]

I have a F3 for a few months already, and it's a keeper.

However, it DOES NOT LIKE passive crossovers. 15W are enough to drive directly a fullrange or midrange of 95db+ efficiency.
Preamp match is also difficult with a tube-like impedance.

[PaulFolbrecht]

I have a F3 for a few months already, and it's a keeper.

However, it DOES NOT LIKE passive crossovers. 15W are enough to drive directly a fullrange or midrange of 95db+ efficiency.
Preamp match is also difficult with a tube-like impedance.

I really have to disagree about your crossover comment.  I drive my Audio Note AN/Es with the F3 and it is very dynamic and snappy and sounds extremely good.  In fact it goes toe to toe with my favorite 45 SET amp in terms of tonality (and is more dynamic and extended).

My transformer-couple Audio Note Kits L3 seems to be a perfect match as well.

[sts9fan]

I would also disagree on the crossover comment.  I have used mine ( Zv9)  with a few crossovers, no crossover and 1st order high pass filters.  All with great success.  Also I think Nelson would disagree that it is difficult to match a pre to.

The input impedance is the IHF standard of 10 Kohms, and the input capacitance
is very low, so you should find it easy to drive with tube equipment if you like. It
would be a pitiful source that would not be able to deliver 240 micro-amps
required to clip this amplifier. The amplifier is largely indifferent to the source
impedance of your preamp, so a high source impedance is not a problem.

Low gain is the only issue so you would want the pre to be 12-20db.   

[PaulFolbrecht]

I would also disagree on the crossover comment.  I have used mine ( Zv9)  with a few crossovers, no crossover and 1st order high pass filters.  All with great success.  Also I think Nelson would disagree that it is difficult to match a pre to.

The input impedance is the IHF standard of 10 Kohms, and the input capacitance
is very low, so you should find it easy to drive with tube equipment if you like. It
would be a pitiful source that would not be able to deliver 240 micro-amps
required to clip this amplifier. The amplifier is largely indifferent to the source
impedance of your preamp, so a high source impedance is not a problem.

Low gain is the only issue so you would want the pre to be 12-20db.

Yeah, I'm aware Nelson says source Zout doesn't matter and I bet he's right.  Anyway, a low Zout is always good!

My AN/Es are realistically about 95 dB/W and the AN pre's gain 18 dB.  The vol control is normally open a quarter to a third, with about 12:00 being the max and very loud on most material.  So, with reasonably sensitive speakers a moderate-gain pre would be just fine.

[dspringham]

Paul,

Any comments on the F-3 pushing your Tonian TL-D1's?

Dave

[PaulFolbrecht]

Paul,

Any comments on the F-3 pushing your Tonian TL-D1's?

Dave

Also an excellent match.  Since the Tonians are just a bit hot in the midrange the slightly more mellow mids of the F3 compared to the Korneff 45 is nice. The Tonian speaker seems to be a bit more efficient than the AN/E and so the extra power of the F3 isn't as noticeable.

Basically every permutation of these two speakers and amps is heavenly.

[Don Reid]

I have owned and used a pair of First Watt F3s to power the midrange and tweeter driver/horns of my triamplified DIY horn system for about one and one-half years.  Sensitivity of those driver/horn combinations is 109 dB/1w/1m and 106 dB/w/m respectively.  The F3s replaced Cary Audio 2A3 SET monoblocks driving the same speakers.  I have been very pleased with the change.  The F3s have all the intimacy and immediacy of the SETs but even greater clarity, transient correctness and purity.  I am a big fan of this example of Nelson Pass' design talent.

[bellicon]

I don't know about the F3, but the F1 and F4 run quite hot -- 50 degrees C or more, so don't know if that's a consideration or not.  I believe you can build a lower power version of the F4 that may run a bit cooler, but I may be confusing this with something else.  BTW, the F4 is basically a unity gain (actually very slightly less) current buffer amp, or impedance converting amp, that depends on the linestage for voltage gain.

Actually, I did read somewhere that, in part because its push-pull, the F4 allows you to turn down the bias on it a bit so that it will stay in Class A for just the first 7 watts or so. This may allow you to drive high sensitivity speakers at moderate levels with Class A sound and yet not heat up the room as much. Has anyone tried this?

[bellicon]

I, personally, think the Aikido amp is just about the perfect gain stage for the F4.  Apparently I am not alone, since many others have already done this.  I ordered some F4 boards to play around with at some point.  6SL7 into 6SN7 yields around 29dbs of gain with low noise (due to noise canceling), low distortion and low output Z.

Do you happen to have or have ever owned any tube amps? 300B SET or PP? 845? If yes, how would you compare and contrast the sound of the F4 to them?

Yes, quite a few F4 owners have been very pleased with the Aikido preamp. But as you probably know, there is another notable diy preamp, the Impasse http://www.audioxpress.com/article/The-ImPasse-Preamplifier I’m curious about what you think of its design compared to the Aikido and why you may prefer one, in some respects, over the other.
 
Are their different (unbalanced) versions of the Aikido?

And has John Broskie or others implemented any revisions that improved overall performance since the original design?

My speakers are at least 94db sensitive, my room is 16 ft x 14 and my ears can’t tolerate average SPLs much beyond ~ 60db-at least not much above the lower midrange band (i.e. allowing for the Fletcher-Munson effect). My midwoofers are cut off below 70Hz, where my pair of Rythmik 12" sealed powered subs take over.

Thus, the line stage may not need to put out much more than 8V to 10V rms, if that much. Yes?

Except for the subwoofers, my speaker system is a clone of Gary Dahl’s Azurahorn 425/Radian 745 Neo Be/GPA Altec 416 system.
http://www.diyaudio.com/forums/multi-way/100392-beyond-ariel-720.html

And are there certain tube suppliers of specific brand tubes in the Aikido who you would recommend for best performance with my speakers, such as http://www.sophiaelectric.com/ ?

Have you been pleasantly surprised when “tube rolling” the Aikidio, especially when driving the F4?