Head-Direct EF-1 - Page 2

A second thank-you! Found the RCA "clear-tops" NOS with organ company branding for $19 and ordered some from BRENT JESSEE RECORDING HOMEPAGE.

A test with 701's? Burning those in now, and the amp with the used RCA, then will burn in the new clear-tops. I have very high hopes. I might even leave the 701's unbalanced if the sound is great. [Principal use was going to be with Senn 600s since I can switch myself between bal and SE].

I agree this is a perfect 2nd amp for a nightstand or a secondary listening post.

Last night when I took a peak at the sound after 24 hours of burn-in I thought the amp was quite warm to the touch. So I said, short of putting a new cover or drilling into the existing cover how could I improve the air flow to keep the amp cooler.

Then I remembered I had some o-rings laying around so I took the plexiglas cover off and replaced the small steel washers (4) w/ small o-rings. This raised the plexiglas cover but IMO did not create a wide enough gap. Thus I went up in size of the o-ring and since the bass is wide enough it accommodates the larger o-ring w/ out protruding.

Here are a couple of thumbnails comparing the size of the o-rings to the original washers. Please click on the thumbnail to view the full size picture.



While I took the cover off I took a couple of pictures of the internals. Here are the thumbnails. Once again please click on the thumbnail to view the full size pictures.



The next two pictures attempt to show the gap the o-rings created between the plexiglas and the bass. The amp is definitely cooler to the touch. You should be able to see the Herbie's Halo I have also installed on the Chinese valve.



I noticed that the stock feet are made of hard rubber and do not raise the amp much. I felt that the amp could benefit from more separation from whatever you lay it on. So I had a set of "Isonode" anti-vibration feet and installed them I hope this tweak will also help to reduce vibrations from reaching the amp. Here are a couple of thumbnails of the mod.



More to follow ...

Both burn-ins well underway: 701's and the EF1 with the RCA tube (96 hours).

Big YES on 701's and this amp.

Listened to a few hours of classic rock and was transfixed. Amazing.

Next up: Senn 600's (it was voiced for this) and classical.

What was the size # of the o-rings? How does the cover come off, doesn't look like torx or phillips to me, help I'm a newbie at plexi covers.

If you make better, thicker, no-writing, smoke color, more air vents plexi covers count me in as a buyer. Heck I'll even fund the R&D (assuming I can get the cover off myself!).

Thanks, great work and info, I am going to clone.

Try a 3/8" by 9/16" o-ring and a 5/64" allen. Finger tight only, do not use a lot of force. As far as the plexiglas I would have to look into it.

Got it, thanks! I can live with the writing on the plexi I guess. Love your idea of the o-rings!

My review sample of the EF-1 arrived today. I immediately put in an RCA clear-top 12AU7 and fired it up. I will be doing a full review, but I can say now that this is a good sounding amp.

Try getting the lettering off with a sugar cube. I heard that's good for getting things like logos off cellphones and the suck - worth a shot.

Is there a part # on the Lowes blister pack?

COUNT ME IN on a group buy of the smoke cover with holes!

malldian wants to erase the letters with a sugar cube. The last time I saw such a thing I believe my college roomate was experimenting with LSD. Matt, can I use a pack of Equal instead?

I'll defer to Skylab for the full review, but with an RCA I listened all weekend, collecting as many HPs as my extended family would lend me. Unfortunately the beyer 880/600's (my fave) were MIA, and the D2000 went missing. But, on classic rock 24x7, here is the pecking order of the rest according to me and my friends:

AKG 701s
Ultrasone Pro 750's (closed ... strange it did so well)
Senn 600's
ATH-AD2000

Very surprising. The amp is voiced for the 600, but the 701s blew the Senns away with this tube. Maybe for classical it would have been different.

The real shocker is the AD2K, which should be great on this music. Not at all with this amp, acceptable but below the others for sure. Perhaps this particular pair needed more break-in, who knows.

If you have 701's, buy this amp. I listened hours beyond what I planned with this combo.

Disclosure: high-end hearing rolls off a little at my age. But I have younger friends who agreed with me.

Wavoman, did you feel the RCA tube improved things versus the stock tube?

Nope, but I googled a bit so your opinion of me wouldn't be forever damaged. Sugar cubes only. I would wait till you know are getting another or test it on the corner before you go at it.

How to remove Logos from your PDA / cell phone with sugar

Never tried the stock tube, sorry. Everyone said the only place to put these Chinese tubes was in the trash, so I did.

Sweet! Actually, I'm going to try cream and sugar, since that's how I take my coffee. Do you think I should remove the cover first, or perhaps we will discover a new tweak: putting cream and sugar drops in your amp tightens the sound, like a horse blanket has suddenly been pulled off the speakers, and blackens the blacks.