Belles 21a preamp

dr1978 · January 12

marvda1 wrote: »

@dr1978 open that puppy up. here is an internal pic with auricaps. i recall david belles saying you don't have to replace that fifth cap up front.

I emailed Dave at Power Modules to see if that serial number label indicated that they did the upgrade. Indeed it does. But I'll definitely open it up as soon as I get it.

audioluvr · January 12

Dave's kind of a slow responder. Probably one of those eccentric genius idiosyncrasies. Looks legit though.

dr1978 · January 13

@marvda1 crazy, guess what the throw in tubes are...

dr1978 · January 13

Unfortunately I can't get the sucker open! The screws on the side are ridiculously small. I had a tool for the ones on the faceplate, but I'm at a standstill with the others.

I think I do spy the auri caps though..

dr1978 · January 13

Does this look like a homemade power cord?

marvda1 · January 13

dr1978 wrote: »

@marvda1 crazy, guess what the throw in tubes are...

mullards?????

dr1978 · January 13

From my other thread..

marvda1 wrote: »

@dr1978 make sure you use good quiet tubes in the belles.
here's one you can try while it's cheap.
https://upscaleaudio.com/collections/preamp-tubes/products/ge-12au7-6189w
i bought a pair of radiotechnique 6189w when they were $60 ea. now they are $95 ea.

dr1978 · January 13

Haha, whoops. I thought that link was for the radiotechnique 6189w. That's actually what he sent. Do you know how I can tell what grade they are?

Sorry, my posting is a mess tonight, too much excitement!

marvda1 · January 13

not sure but if you have the box with the upscale audio label on it see if it is graded noise-A and microphonics-A

dr1978 · January 14

Sure is. No clue what it signifies, but I see that the T2 values of each don't match.

pitdogg2 · January 14

dr1978 wrote: »

Sure is. No clue what it signifies, but I see that the T2 values of each don't match.

The triode difference is not unusual.

audioluvr · January 14

The allen wrench for the side screws is really small.

dr1978 · January 14

Do you happen to know what size it takes? Or did your unit come with it? I have a decent multi-tool, but the smallest isn't quite small enough.

audioluvr · January 14

I'll check. I'd run it as is for a baseline.. Could be what's in it are really good tubes.

dr1978 · January 14

For sure, I'm not planning on swapping them out for a while, just curious.

marvda1 · January 14

Let's get to the important part, "Da Sound Boss, Da Sound"

dr1978 · January 14

Ha, ok ok. I didn't get to devote much time last night, but there were some moments that immediately stood out. Specifically on songs with rich vocals or a lot of atmosphere...those elements were magnified and had me feeling like I was swimming in them. Codex by Radiohead was probably the highlight. One of my least favorite songs on their The King of Limbs album, but I was entranced last night.

Definitely can't wait to do a ton more listening to find some less obvious attributes. Those that lobbied for a tube pre in my upgrade thread were of course on the money. I couldn't be happier with how everything turned out though.

marvda1 · January 14

also pay attention to the bass.

dr1978 · January 14

I'll do that, and I'm glad you brought up bass. I really enjoyed listening to my 705's in full band for once, and didn't find anything lacking, but I was wondering if there was a way to integrate a sub with the 21a. I've got the HT Bypass hooked up and working, but I wasn't sure if I could turn this into a 2.1 setup for music.

audioluvr · January 14

Sorry for the delay. Side tracked. Those small screws take a 3/32" allen wrench.

dr1978 · January 15

audioluvr wrote: »

Sorry for the delay. Side tracked. Those small screws take a 3/32" allen wrench.

Thanks a ton, I'll have to head out and get one.

dr1978 · January 16

Any drawbacks to connecting the balanced output from the Belles to the balance input of my svs? Seems like that might do the trick. I'm using the unbalanced connections for pre to power amp and Marantz to svs.

pitdogg2 · January 16

Some gear will only do one or the other.

marvda1 · January 16

ok the 21a is not truly balanced, so if the svs is truly balanced i don't know how hooking one to the other works.

dr1978 · January 16

From the Soundstage review...

"the 21A's circuitry is not fully balanced, however"

dr1978 · January 17

Mullards?

dr1978 · January 17

Here's the whole thing..

audioluvr · January 17

I think that's a 12AT7 which is the wrong one.
Edit: Brimar 12au7
https://reverb.com/item/33830323-nos-brimar-ecc82-12au7-pair

dr1978 wrote: »

Mullards?

pitdogg2 · January 17

audioluvr wrote: »

I think that's a 12AT7 which is the wrong one.

dr1978 wrote: »

Mullards?

CV4003 is the designated number for the civilian valve known as 12au7.

If you want to know the maker we'll need many more pictures on structure and or any other markings. Could it be Mullard .. yes Could it be another foreign manufacturer that copies those markings ...yes

Mullards were made in Great Britain and also other european countries that mullard contracted out to. Before Mullard went to Russia they had also been made by a company in Japan.

True Mullards not sure.

dr1978 · January 17

Thank you sir. I already closed it back up, when I get the itch to try the radiotechnique's I'll take some more pictures.

Belles 21a preamp

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