AOS Exclusive Review of Eco-Fan Sound Pre-Amp and Power Amp

[Techno Commander]

They look like I15's with the grilles removed.

[Alex_UK]

That's great, thanks for clarifying.

[Giant Haystacks]

hi jack thats a lovely skirt you have there you remind me of the monks in the mountain monastrys in italy ,i will have to send you over some bottles of whiskey for christmas.
there were 2 hifi shows in ireland in last 2 weeks one in n.ireland in belfast and mr cloney had one in dublin i was at both .i was speaking to a uk valve amp maker called pure sound and was telling him about your new amp circuit -he said about using transistors in a similalar way i wrote it down his description but cant find now. he had his linestage which had a 300b in it and 845 mono blocks on demonstration -he said that he prefered 845 to the 211

[Jack Williams]

I'm told they're CTA 15s. Does that ring a bell?
Jack.

[michaelhigh]

Just to read about such audio delicacy is amazing; to live it and breathe it must be intoxicating. As a musician I struggle with kit that can barely translate the complexities of the sound I envision, especially as I've been playing at/with electronica more and more and pop stuff less and less. I could only imagine the thunderous reproduction of my sonic mayhem with such beautifully simple, unfettered equipment. My speakers are a lash-up at best- never mind the awesome combos you guys are running. From a true lover of all things musical, I applaud the spirit of this undertaking and only wish the best upon those involved with these awesome animals. Rock on in the very best way, all of you, to your own best end, whatever that seems to be in the midst of the discovery of how well your gear is being received...

[Jack Williams]

The tremendous Mediaeval Baebes have got their new double album "Temptation" at the manufacturer at last, available for Christmas. Their two existing DVDs, "Live at Gloucester Cathedral" and Tenth anniversary one are absolutely supurb and continue to be my highest "rotation" DVDs. Only available from their site these days. www.mediaevalbaebes.com

[Jack Williams]

Well, the push-push circuit does in fact work a treat. I did find though that I do need a bigger power supply and more HT for four of type 45 in this circuit than for two of 6A3 in single ended. I really need some 100 extra volts to get the best out of it but as is I do get about 4wrms/ch to listen to. Even that though, sounds quite grunty compared to a single-ended 45. But the sound is quite beautiful, in fact when I first got a channel of it going on Saturday, and then tried the local classical music station on the rubbish bench speaker that's what came immediately to mind: how beautiful it sounded.
On the livingroom speakers last night the bass was quite impressive on DVD. (other than radio, of course the first thing I tried was the Mediaeval Baebes!) That drum was realistic, and it did a great job on the voices. I quite impressed myself!
It ran out of headroom on a heavy "dub" CD in that if you pushed it up too much it intermodulated, but the depth of bottom was there. I made the OPTs for about 18wrms. The bigger power transformer will also improve the bottom, regardless of the extra power.
More voltage will ice the cake, but I'll also have to keep an eye on the plate dissipation. If I can come up with 10wrms I'll be happy.

[Jack Williams]

After a couple of nights of extended listening, can't say there is much wrong with the amp as it is. It seems to have enough volume for most things. The bottom end is extended and meaty with good damping. In use at present the amp does not have the power measured on the bench, as I only had one channel set up at first. The power supply sagged somewhat supplying two. A beefed up power transformer will give room for more voltage and taps, but I don't think I can go much more toward AB1. About two-thirds class A right now. The 45s plate dissipation is about seven watts at present, but the current is as high as you'd want to go, although the voltage across the 45s is only 150v. I will develop this direct coupled design for SV-811-10s. Monoblocks. I think they'll be pretty nice.

[Jack Williams]

I thought "Push-push" sounded a bit rude. It differentiated from "Push-pull" though. Balanced single-ended is closer to what's happening anyway.
So "What's Happening"?
Got the bigger power transformer created and installed yesterday. On the tap that got me the original bench results but with both channels going, the amp sounded amazingly more powerful. (It was measuring 3WRMS with smaller transformer both channels going; 4WRMS with bigger transformer) but after some listening I thought the 45s felt a bit hot, so I backed it off to just one notch (20 volts HT notches) above where the smaller transformer was. I'm not sure, feeling the 45s whether they are a lot cooler, but the transformer is noticeably so, so the current must be quite reduced.
But personally, I think the amp sounds better on the reduced voltage/power...
It is surprising how powerful this setup sounds for the low power. On about 94db speakers.

[Jack Williams]

Okay, I have borrowed a friend's 6A3 amp as above for comparison with this new amp. The new one sounds every bit as powerful, perhaps more so I think. Swapping quickly many times between the two amps while pausing on a range of music DVDs I find I do always much prefer the new amp. While there is nothing in it as to the top end, this amp sounds fuller and clearer. Without the 2nd harmonics I would guess. The bottom end sounds bigger and more extended. I think it has a warmer and fatter sound, perhaps more "friendly". More three-dimensional?
I'll try to get a perfected one over for a review in the coming year.
This is the BSEA! It stands beside the SEOTL.