DTBs 6B4G

What people are working on at the moment
simon
Thermionic Monk Status
Posts: 5648
Joined: Thu May 24, 2007 11:22 am
Location: People's Republic of South Yorkshire

#16

Post by simon »

Cheers Dave. I feel like a proper amp builder now with the clipleads and breadboard :)

Fortunately the amp was playing pretty loud and that deflected much of the initial shock of the amp's appearance. When I put Nick's big 120uF caps in circuit the first one gave off quite a spark, so a sense of perspective is still required. I'll try to make the cover this weekend before I get into too much domestic trouble...
User avatar
Dave the bass
Amstrad Tower of Power
Posts: 12276
Joined: Tue May 22, 2007 4:36 pm
Location: NW Kent, Darn Sarf innit.

#17

Post by Dave the bass »

Just to double check I'm buying the right bits...

Valve bases, have i got this right?

0A2 = 7pin miniture
6B4G = 8 pin 'Octal'
c3g = 8 pin 'loctal'

EDIT. Also I fancy pushing the boat out and going for Schottky rectification, any diode recommendations? Any of these from Maplins OK? http://www.maplin.co.uk/Module.aspx?Mod ... Y&doy=26m5

Cheers-me-deers

DTB
"The fat bourgeois and his doppelganger"
User avatar
Nick
Site Admin
Posts: 15758
Joined: Sun May 06, 2007 10:20 am
Location: West Yorkshire

#18

Post by Nick »

For the 6b4g heater supply, no, the heater takes 1A, so I would look at 3A diodes. Maybe from RS or Rapid. I will look up the number later if you like.

The bases are right BTW.

EDIT: 1N5820 from Rapid will be fine.
User avatar
Dave the bass
Amstrad Tower of Power
Posts: 12276
Joined: Tue May 22, 2007 4:36 pm
Location: NW Kent, Darn Sarf innit.

#19

Post by Dave the bass »

Nick wrote:
The bases are right BTW.

EDIT: 1N5820 from Rapid will be fine.
Thanks Nick,

DTB

PS. Neighbours away with their caravan :) ...which means... SE Heaven is in Chez DTB and REALLY cranking it out, gorgeous. Julies got a Paul Weller CD blasting out at the mo. Got it set up in place of WD88 but still using the relay switch board to select inputs powered externally via a little PSU and feeding SE Heaven via the tape out loop.

Spent the whole of last night (well till bedtime!) listening to Abbey Road,Sgt Peppers, Ogdens, CSN1, and Deja Vu. Really nice experience, (we were in a 'back to the 60's vinyl mood)

Very impressed now, great soundstage at reasonable volumes, sounds very different from the other night when we were volume concious. In our living room 1 watt almost enough.

Roll on 6B4 project :wink:
"The fat bourgeois and his doppelganger"
User avatar
Nick
Site Admin
Posts: 15758
Joined: Sun May 06, 2007 10:20 am
Location: West Yorkshire

#20

Post by Nick »

Great.

Yes, the 6em7 is a hell of a valve, in a way its a hard act to follow.

Not bad for something made for use inside a TV :-)
User avatar
Dave the bass
Amstrad Tower of Power
Posts: 12276
Joined: Tue May 22, 2007 4:36 pm
Location: NW Kent, Darn Sarf innit.

#21

Post by Dave the bass »

Nick wrote:Great.

Yes, the 6em7 is a hell of a valve, in a way its a hard act to follow.

Not bad for something made for use inside a TV :-)
Cor yeah, innit just.

More full-on testing this afternoon. Swapping between WD88 and 6EM7, it's close, REALLY REALLY close but i've got to be honest in that WD88 has the edge on extreme top clarity and masses (of course) grunt in reserve.

I've been really blasting for the last 30 min (thought I'd check my e-mail and give my ears a rest) some really heavy funk and rock stuff on LP and CD. Deffo 6EM7 has a lot to offer but it just starts to bottom out (clip) on music containing ultra low bass percussion effects. It just begins to loose that magic 'completeness' to the sound and turns slightly hard-sounding..."loosing it's composure" I think HFW would say.

On the CD Musicology by Prince theres a track called 'Life o' the Party', its a typical Prince 'ev'ry body paaarrrtayy hard y'all sort of song but its driven by an almost entirley percussive backing. There's some low low low sounds that just get 6EM7 to clip at just the point that the volume is adequate for day time listening. Pity really, it's that close to blindingly good.

I'm really enjoying the 'compare and contrast'.

LP gives better imaging I've noticed than CD but we knew already didn't we

Swapping back to WD88 shows where its got that massive reserve of power, honestly it kicks botty. Me proud owner :D :wink:

Right, back to vibes, it's a tuff job but someones gotta do it.

DTB
"The fat bourgeois and his doppelganger"
User avatar
Nick
Site Admin
Posts: 15758
Joined: Sun May 06, 2007 10:20 am
Location: West Yorkshire

#22

Post by Nick »

Oh, yes, I would never expect the 6em7 to compete at being a 30w push pull amp, with a 30w push pull amp :-),
User avatar
Nick
Site Admin
Posts: 15758
Joined: Sun May 06, 2007 10:20 am
Location: West Yorkshire

#23

Post by Nick »

Actually Dave, I just noticed the ecc40 base is described as loctal but thats not the same as the c3g, which is a bigger 8 pin base with a locking pin.

Maybe someone can clarify?
Andrew
Eternally single
Posts: 4206
Joined: Thu May 24, 2007 2:18 pm

#24

Post by Andrew »

Hi Dave,

To be honest I didn't know about the difference between ECC40 Loktal and C3g Loktal so could easily have fallen into that trap. I bought both my C3g and matching bases off an e-bay seller who had the actual bases designed for and matching the valve.

cheers,

-- Andrew
User avatar
Dave the bass
Amstrad Tower of Power
Posts: 12276
Joined: Tue May 22, 2007 4:36 pm
Location: NW Kent, Darn Sarf innit.

#25

Post by Dave the bass »

A quick search shows this chap is selling Loctal bases that are supposed to fit the c3g according to his 'bay blurb.

http://cgi.ebay.co.uk/8-pin-Loctal-Lokt ... dZViewItem

Clicky linky looky.

DTB
"The fat bourgeois and his doppelganger"
User avatar
Nick
Site Admin
Posts: 15758
Joined: Sun May 06, 2007 10:20 am
Location: West Yorkshire

#26

Post by Nick »

Yep, those are the right ones.

The ECC40 base is better known as rimlock (I have been doing a bit of searching).

http://www.radiomuseum.org/tubes/tube_el41.html
User avatar
Greg
Social outcast
Posts: 3202
Joined: Wed May 23, 2007 11:14 am
Location: Bristol, UK

#27

Post by Greg »

Hi Dave,

Good to read all your amp comparison stuff. Before I go on, this post is not about batting for PP or SE. Andrew Ivimey even got me thinking about a Ongaku clone :roll: What I wanted to point out is that you WD88VA (if I recall correctly) is the standard version. Without doubt, spending a bit of time and money upgrading components should bring it to even higher levels of performance. It's worth thinking about and you don't need to sting your wallet with a standard upgrade kit. Plenty advise here on which components to select for change and what to use, albeit, we all have personal component preferences.

Best wishes,

Greg
User avatar
Dave the bass
Amstrad Tower of Power
Posts: 12276
Joined: Tue May 22, 2007 4:36 pm
Location: NW Kent, Darn Sarf innit.

#28

Post by Dave the bass »

Nick wrote:Oh, yes, I would never expect the 6em7 to compete at being a 30w push pull amp, with a 30w push pull amp :-),
That made me giggle, dunno if its supposed but it did :lol:

I've got a (short 1.5Mb) video of the duff 6EM7's being pushed a bit too hard, do they normally arc along with the kick drum in music?!

http://www.dartfordskatepark.co.uk/daves/CIMG6282.AVI

One valve appears to arc between Anode and summink a little when being pushed hard with a bit of 'fonky Princey-poos'. Andrew I's donor 6EM7's don't do this (thankfully).

DTB
"The fat bourgeois and his doppelganger"
User avatar
Dave the bass
Amstrad Tower of Power
Posts: 12276
Joined: Tue May 22, 2007 4:36 pm
Location: NW Kent, Darn Sarf innit.

#29

Post by Dave the bass »

Nick wrote:Yep, those are the right ones.

The ECC40 base is better known as rimlock (I have been doing a bit of searching).

http://www.radiomuseum.org/tubes/tube_el41.html
Phew, glad they're the right ones. I've got 4 of them, 4 Octals and 4 Mini 7's on the way.

A mate of a mates mate who used to be a bit of a 'layddez man' had 'Rimlock' once but thats another story............. :shock: :D Arf Arf.

DTB
"The fat bourgeois and his doppelganger"
User avatar
Dave the bass
Amstrad Tower of Power
Posts: 12276
Joined: Tue May 22, 2007 4:36 pm
Location: NW Kent, Darn Sarf innit.

#30

Post by Dave the bass »

Greg wrote:Hi Dave,

What I wanted to point out is that you WD88VA (if I recall correctly) is the standard version.

Best wishes,

Greg
Yep, you're right Greg, mine is the standard WD88VA. Sure I could upgrade coupling caps and diodes etc etc but when it sounds as luvverly as it does already is there any need?

Now, if project 'Komrade DHTski' blows WD88 out of the water THEN I'd think about upgrading to an XL-esque WD88 spec :wink:

Seriously though, it's been a really fun afternoon and evening.

Thanks for the tips Greg,

DTB
"The fat bourgeois and his doppelganger"
Post Reply