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Hello.
I'm venturing into SETs for a system I'm building and wanted to check my rationale with knowledgeable folks here.
I'm building a 4-way active system, with a pair of subs and midbasses to take care of frequencies below 400Hz with their own SS amps (400W).
Tweeters are 104dB/W and flat impedance at 5 ohm and midranges are being worked on but close to 103dB/W and 12ohm (minimum impedance is 8.8 ohm).
The system will be active and I'm thinking of using a Yamamoto A-08S to drive the tweeters and another A-08S to drive the midranges.
My room is 25m2 (269ft2) and 3m (10ft) high. So a medium-sized room.
Most of the music I listen to is not large-scale orchestra. Jazz, blues, and rock. Some is heavy on the bass dept, but that shouldn't be an issue. I usually listen at 85dB SPL, and sometimes at 90dB (as measured on a Radio Shack handheld SPL meter, C-weight, set to fast) - peaks of course are much higher.
I wonder if having a 45 SET to drive the treble (above 2kHz) and another 45 to drive the midrange (400 to 2000Hz) will be enough. What do you think?
Follow Ups:
The Yamamoto A-08S is UNDYNAMIC, as are 99% of the commercial Type 45 amps out there !!!
You can DIY build a dynamic Type 45 amp, that will creme any 2A3 amp in dynamics, but ONLY if you have a GOOD LSES power supply, and proper attention is paid to wiring, in the amp and to the drivers.
There is, IMHO, only one really good, commercial SET amp out there, and Dennis Fraker of Serious Stereo is the man who builds it. It is cheaper than spending ones money, and life-time, on second rate solutions that really don't cut it.
Now, given a SET with a good supply and really good wiring, a 2A3 will outperform a Type 45, and perhaps the main reason will be a 2.5K secondary , with lower DCR, than a 5K secondary. BUT, no one I know, except Dennis, can build, or listens to such amps. I am waiting on the world to do so !!
There no reason to think that "serious stereo" is better then any other builder. They use no special transformers, actually it looks as if they use standard EI types with high coreloss and more distortion the modern c-cores
Edits: 09/02/16
Hello Lenin,
This is the second time you have posted about E-I cores, and you are RIGHT about it.
It should be a modern C Core and or a Toroidal core ( Menno Van Der Veen ).
You are not in the USA. At RMAF many many years ago, in Terry Cain's listening room, there was a huge after-hours SET amp showdown, and the Serious Stereo amps wiped-out all the rest, they gave Dennis a standing ovation. Nothing has changed, to my understanding, since then.
Likely, the core-type you mention, and also the toroidal core, will be evaluated in the future. These should be even better than E-I.
There is MUCH more to a successful SET implementation than just the core-type, as we hopefully know. "Everything" in the SET implementation matters !!
Your comments are noted and appreciated, I generally agree with them. Thank you very much.
Jeff Medwin
You sound a bit sarcastic....
Luckely i live in Europe and we know " there are many ways to Rome"
Hi Lenin,No, I did not intend to imply sarcasm - at all !! You are 100% correct about E-I core types.
Honest. I was sincere. we will evaluate different cores in the future !!
Was discussing this topic with a good friend, just TWO DAYS ago, privately.
Jeff
Edits: 09/02/16
Take an amplifier that is *NOT* so power limited and scope its output when connected to the speakers and see how often it exceeds the ~1.7 Watts a 45 is capable of.
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
IME, the 45 will be enough and is a good fit for the midrange and upper range. However the 45 could not provide enough dynamics for my tastes even with my 100+ dB horn speaks. I like the JJ2A3 better. Also, I would prefer a 2 amp system with solid state on bottom and tubes on top to keep things simpler but again....just my preference.
Have fun and let us know how it turns out.
Jim
Hey Jim.
Thanks for the input. Yes, dynamics are a concern. In fact that is what's mostly behind my question around whether they have enough power for the job.
People have commented about the sensitivity of the driver, but not about the impedance. I'm puzzled. It is my understanding the SET amp develops a certain amount of power at certain voltage, so using a 12 ohm 104dB/W driver should be better for dynamics than an 8ohm 104dB/W driver. Right?
"12 ohm 104dB/W driver should be better for dynamics than an 8ohm 104dB/W driver. Right?"Nothing sets in stone here! Depends on your speaker's true impedance curve, the amplifier circuit, transformer load to the output tube matching and the Output transformer's true impedance ratio.
This requires try and true approach and listen to the speakers at different tap. Generally, a higher impedance 16ohm tap will provide almost twice the voltage of the 8ohm so it sounds louder so it may sound a little more dynamic at the same amount of volume at 8ohm but some music may suffer.
And depends on the type tube and and the amplifier circuit, using the wrong impedance tap for a long period of time may shorten the output tube life due to the more stress placed on the output tube. And people have to wonder why they need to retube often?
45 has a really good tube life for normal use!
.
.
.Thou shall not stand where I type for I carry a bottle of Certified Audiophile Air and a Pure Silver Whip.
Edits: 08/26/16
A couple of questions from the DIY speaker builder. Why crossover at 400Hz? There is a lot of vocal contents above 80-100Hz and lobing is apparent anything between 100Hz-3KHz. I know the active XO helps but not you won't get as clean sound as crossing outside of the 400Hz. I also know that some JBL, Altec speakers did that but I am not a fan of such speakers and IMO not very HiFi sounding stuff to me.
Normally, a 45 SET works pretty well if you have 100dB+ efficiency speaker so a single 45 SET amp should work well above 100Hz to 20KHz and beyond if you have passive XO in your speaker and uses a sub for the 100Hz and below. Of course, you can use two 45 amps with active crossover (at 100Hz/2KHz) and compare them which sounds cleaner.
.
.
.Thou shall not stand where I type for I carry a bottle of Certified Audiophile Air and a Pure Silver Whip.
My current speakers' midbasses are crossed over at 350Hz. The ones I'm working on will be somewhere between 300 and 600Hz, frankly. Tests will tell, and changing xo points and slopes is very easy with my setup, so will be a matter of trials. My midbass drivers are used on some MTMs with good reviews playing up to 1200Hz or so, so their performance up to 600Hz is good.
Some people ara adamant about not crossing over within the vocal range while others say it doesn't matter as long as you do it right. And digital linear phase crossovers and time-aligned drivers seem to be a good route to a good implementation. So I will try it and decide.
FWIW, I have subs playing to 80Hz on their own channels (again, TBD somewhere from 60 to 100Hz) and midbasses playing from there to 300-600Hz. Midrange above that, and then tweeters.
I might try a passive xo between midrange and tweeter after I decide xo point and slope with the active setup. Lots of fun! :-)
Why not trying an E55l in triode connected?
More linear, more reliable, long life and easier to work with.......
Sorry, but E55l aren't on my radar. I'd rather look into the "usual SET suspects" for an initial venture. I'm building a speaker too, so don't want to go overly complex in the first stage. 45 and 2A3 are in the shortlist, with 45 having a bit of an edge in terms of my preference. Coincident Dynamo 34SE SEP could also be a more powerful option, but if 45 have enough power I think I'll go with the A-08S.
I have a direct coupled amp that plays the 2A3 and 45, with a rectifier substitution. I prefer the 45, but i think mostly due to the mids where i spend most of my time anyway (not the treble, as you plan).
Direct coupled amps tend to be a bit more noisy than cap coupled amps, so i wouldn't take the DC route. But as i am sure you know, there are a lot DIY schematics out there for the 45.
Frihed89, your post sent me looking into whether the A-08S is a direct coupled amp or not.
According to the Stereophile review by Art Dudley it seems the A-08S is not DC (although the first gain stage is capacitor-coupled to the 45s: "The 717A's anode is capacitor-coupled to the signal grid of a 45 triode").
But acccording the 6moons review by Srajan "By DC-coupling the 45s and 717A drivers, noise levels for the revised amp are given as 0.3mV to 0.7mV".
Do you happpen to know which one is right, and whether the A-08S is DC or not?
No, I don't. I looked at a couple of shots of the internals, and the use of turret boards confounded me. I don't have them on my Fi Audio 2A3/45 monos.
Maybe the best thing is to send an email to Jac-Music and ask. On a speaker amp, it may not matter, although your treble unit is quite sensitive. AC vs DC to the filaments is another noise issue, perhaps even more important than the coupling strategy. It is a controversial topic and there is no last word.
Sadly, there are not many commercial 45 amps on the market.
Thank you.
As usual there are multiple paths in audio. But the key takeaway from this thread is a 45 driving a tweeter and another driving the midrange should be enough. This was my critical question. So I'm happy.
Then, as usual, there are multiple other aspects to take into consideration regarding implementation. I'm taking note of noise as a potential issue, particularly with the tweeter amp. All the reviews I've seen about the A-08S highlight how dead silent it is for a SET, so that's a good start.
Many think highly of your Fi Audio too - aesthetics skews my wife's opinion towards the Yamamoto, though, since this will be in the living room.
I would be interested in discussing with A-08S owners. Please let me know if you know of any users here with experience with these amps.
Thank you!
I got in when it was 6 months. I'm very happy with it. I only use it with the Type 45 these days.
Its cap coupled, I've looked inside and seen the circuit. There are FAR better alternatives available. Don't waste your money. LOL, especially on two of them !!I use a Type 45 DC amp on my wire-modified ALTEC VOTT A7-800s. As "I" DIY build it, it has power and dynamics to BURN !!!
I have a friend in KC, MO who runs ONE A-08S on his ALTEC ( A-4?? ) system with a total of FOUR 515Bs and two 288s. The speakers are set up in a converted turn of the 19th century decommissioned fire house.
Contact me, and I will give you his contact information, so you can talk to him directly, hear what his direct experience is !! He had my prototype, a DC 45 amp for about two months on his system in 2015, and went back and forth comparing it to his A-08S 45 amp. You really need to talk to him !!
The ONLY commercial amp I know of in all of audio, that cuts the mustard, is the Serious Stereo 2A3 amp, it trashes everything else in the SET world, and DC set world, handily !! They will be at RMAF, Denver, October 2016. Call and talk to Dennis, he will help you , he KNOWS.
The quad amping, ( which you are thinking of ), adding a (1) an extra active stage and (2) using dissimilar amps with different signatures and timing - on EFFICIENT SPEAKERS - will be an UNfixable degrade compared to a well-executed passive crossover, a single GOOD amp, and a two or, at the most, three way speaker.
Remember this, it will save you much wasted time and grief :
KISS "rules"
in ultimate performance high-end audio set ups.
Jeff Medwin
Edits: 08/23/16
Right. An $11k amp sounds better than a $3k. It better do!
Can you point me to better SET alternatives within comparable prices?
I'm already actively running my system now. I've gone from "purist" to digital XO, DSP, time-alignment and I'm not going back. I know others don't share the point of view, and that's fine, while others do. I am now working on new speakers and replacing amps, but not revisiting the system concept.
Good suggestion sent, via email. An amp from China maybe.
An 11k amp is always overpriced and you probably help to pay the new Mercedes of somebody else...... Did i see a cheap EI transformer too?
Dc coupled is not a good idea, less reliable and there is always an electrolitic capaciter in the circuit path for bad sound. A normal capacitor is normally a lot better. If you want the bst is should have a 1:1 interstage to drive the powertube.
Lenin,
Respectfully, you are not well informed and not experienced in this.
But, ask yourself this : regarding coupling mechanisms :
HOW will a one-to-one interstage be better at signal transmission than three paralleled Cardas pure silver audio wires ( the direct couple mechanism )? How??
And please tell me, WHERE is there any electrolytic in such a circuit?
DC amps need not use an electrolytic, ones I make use 100% film caps everywhere !!
The amps are $15K for two monoblocks, last I saw, and READ all the user-reviews on it ( URL in my post above) obviously you have not !!
Jeff Medwin
If it is real dc coupled it should not have anywhere in the circuit a capacitor, not cathode de-coupling and not in the power supply. I doubt if you have a real dc amplifier, you have any schematic of it?Cardas silver is just a brand and just silver, nothing special to me. I have heared many fairytales about silver, silver can not do magic it is just in the mind of the person who uses it who thinks it dos magic. Btw silver is a "cheap" metal and cost less then $1/gram, even the cardas silver.
I also have heared many $10k amp/ loudspeakers and other top dollar equipment and i have never heared any of them worth the money. Some sounded really well but not worth that kind of money. It is mostly snobism.
A interstage has the best controle on the grid of the powertube.
But... If i see the work of Josh from Electronluv i will make an exception because its a peace of art if you look at it. (Not buying it for the sound)
Edits: 08/23/16
Thats incorrect.And also your comment about bias shift is also incorrect - it assumes too much, and negates certain developments (yeah I know, but I do these things).
Shane.
Edits: 08/31/16
"A interstage has the best controle on the grid of the powertube. "
Why is that?
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
When using a interstage you have the possibility to have a rock solid bias because of the low dcr of the interstage. Of course you have to use a capable driver tube and use a stable fixed bias of the power tube otherwise you though away all the goods.....
Dc coupled tubes have drift ( not the best bias) and using capaciters for cathode decoupling is also not a good idea for the best performance.
An interstage can also provide for class 2, drive with grid current, if propper designed.
"...have a rock solid bias because of the low dcr of the interstage. "
I used to think that also but then someone explained that the grid current is not DC per se.
The grid current will start and stop periodically in accordance with the music signal that is causing it.
So now it is the reactance of the winding that comes into play, not the DCR.
A good grid choke (or the secondary winding of a good IT) will have a very high reactance, in many instances higher than the grid resistor that it replaced causing the bias to be less stable under class 2 conditions.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Grid current can only be there for very large signals where the grid of the powertube is driven in a postive grid signal. Then there is a much lower impedance so the driver has to be much more powerfull then normally. A normal circuit can't handle this but a powerfull driver+ interstage can.Remember this grid current is a very special situation where impedance is much different then normally so an interstage is still the best solution for a stable bias.
Edits: 08/25/16 08/25/16 08/25/16
It should be enough.
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