DTBs 6B4G

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Dave the bass
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#151

Post by Dave the bass »

Evening all,

Stayed behind after work to play a bit more as the workshop was in total silence I could really listen and experiment.

But first a bit of back-tracking.

Yesterday he was mono and looked like this...
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But sort of worked after being fed by the engine house...
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Then after an early start today he gained an identical twin that was lashed up next to the other so i could compare voltages and spot where I'd gone wrong...
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...and 'cos the little vice swivels I it makes it easy to test voltages like this...
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After a bit of a to-do with oscillation solved by Mr G and a 1K resistor (but sadly no 180pF cap, we haven't got any) he got to this stage...
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Then after much relief and fiddling about he started to sound better so I gave him a bit of a tidy up...
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...and after a bit of playing about found that the coupling cap on the right sounds better than the one on the left...(and yes I know I haven't soldered one leg on and there's a loose wire..)
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After finishing off (for tonight I just sat and listened and I must say even without the correct o/p TX's it now sounds bloomin' impressive to my ears, after removing the little metal-something-or-other caps (EDIT they were Metal Polyester 0.22uF 250V)and putting in those big Polypropolene / Polyester (?) ones that I found in the bottom of my parts box (think they were surplus from a job a while ago) the sound really improved to me. It's deffo as loud or even louder than 6EM7 but smoother. It copes with modern sampled percussive dance-music better than SE Heaven already so as you can imagine I'm a happy (but tired) bunny tonight.

While I was faffing about I used a plug-in wall wart mains tester and was amazed to find that the whole amp pulls 134W from the mains (0.6A) and has a power factor of 0.94. I also disconnected the mains TX before the bridge to see how much current was being pulled and measured 277mA AC between the TX and the bridge, gulp. The TX is only rated at 165mA, it sure thrashes that poor little TX. It's gonna pop I reckon.

Anyway, if you've made it this far you must be as knackered as me :lol:

BFN,

DTB
"The fat bourgeois and his doppelganger"
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Dave the bass
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#152

Post by Dave the bass »

Julie has just phoned me at work, the caravans next door is going which means I can make a lot of noise this weekend :D

DHTski's going home for a right proper session, which means I've got to do what I said I wasn't going to IE- take 6EM7's o/p TX's off him. I feel mean and heartless :(

DTB
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Darren
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#153

Post by Darren »

Murderer !!! :shock:
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Dave the bass
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#154

Post by Dave the bass »

Darren wrote:Murderer !!! :shock:
:D Is it possible to be put away for Violating an amp? :shock:

DTB
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#155

Post by Darren »

Absolutely ..... or should be !!!

Don't forget the gathering of solder sniffers coming soon, watch ya back Dave :wink:
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Dave the bass
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#156

Post by Dave the bass »

Darren wrote:Absolutely ..... or should be !!!

Don't forget the gathering of solder sniffers coming soon, watch ya back Dave :wink:
You could make a young 'un paranoid y'know Darren :)

DTB
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Nick
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#157

Post by Nick »

Blame me, for not sending you the 2k5 TX's yet.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
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Dave the bass
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#158

Post by Dave the bass »

Nick wrote:Blame me, for not sending you the 2k5 TX's yet.
OK.

Its your fault 6EM7 has been mugged :wink:

DTB
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simon
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#159

Post by simon »

Dave the bass wrote: :D Is it possible to be put away for Violating an amp? :shock:
This week's violation is next week's recycling Dave. You're on the slippery slope now. :wink:
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Dave the bass
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#160

Post by Dave the bass »

simon wrote: This week's violation is next week's recycling Dave. You're on the slippery slope now. :wink:
You're not wrong there Simon, BOBA's looking mighty scared now 6EM7's been whumped!

I was thinking last night, within 9 months I've built 3 DIY amps and a WD88, I'd better find another distraction :) (Oh, a L99 is sitting in the cupboard waiting for a re-plinthing and tune-up, that'll keep me away from amp building).

DTB
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Nick
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#161

Post by Nick »

now 6EM7's been whumped!
To be fair though, it was always going to find it hard with your speakers.

Moving into evil mode now:

Didn't you say the 6em7 was almost as good as the 88 in some areas?

:twisted:
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Dave the bass
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#162

Post by Dave the bass »

Nick wrote:
now 6EM7's been whumped!
To be fair though, it was always going to find it hard with your speakers.

Moving into evil mode now:

Didn't you say the 6em7 was almost as good as the 88 in some areas?

:twisted:
Yup, 6EM7 just didn't quite go loud enough for me, that was pretty much my only gripe. I listen to a huge range of musics and some of the hard funk/pop/dub stuff just made 6EM7 fart out. The only other thing I found was when I was doing side by side comparisons I eventually worked out that SE and PP sounded different at the top and couldn't decide which did it better. WD88 sounded more 'shimmery' but 6EM7 seemed to tell it like it was.

Looking forward to getting DHTski home (which is a task in itself on a motorbike!) and giving it a proper listening to. I just hope the mains TX holds out, it's completely cooking at the moment :shock:

Sounds lovely here though, I even shelled out for a 50K Log Alps pot to put in a little box so I can drive him direct from sources at home.

DTB
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Darren
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#163

Post by Darren »

TBH Dave, the 6EM7 is a fantastic little amp, but power is really the key IMHO.

Even if you don't need the power, it still holds the aces at lower volume.
I gather it's all about headroom, whatever that is :D
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simon
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#164

Post by simon »

Dave the bass wrote:Yup, 6EM7 just didn't quite go loud enough for me, that was pretty much my only gripe. I listen to a huge range of musics and some of the hard funk/pop/dub stuff just made 6EM7 fart out. The only other thing I found was when I was doing side by side comparisons I eventually worked out that SE and PP sounded different at the top and couldn't decide which did it better. WD88 sounded more 'shimmery' but 6EM7 seemed to tell it like it was.
I reckon a nice pair of efficient single drivers would go lovely with the 6EM7 :wink:. You might never need anything more...

SE and PP are different, which one's best is a personal decision.
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Dave the bass
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#165

Post by Dave the bass »

simon wrote:
SE and PP are different, which one's best is a personal decision.
Yep, thats whay I'm slowly discovering. I know Greg is a staunch PP man whereas others are really into the SE sound. It's that difference that has led to me building these amps to find out for meself.

On my speakers at home the differences don't seem as great as mags and BB's make out from what I've heard.

Which leads on nicely to another project doesn't :wink: a nice pair of speakers, slippery slope indeed :lol:

But before that I've got the L99/plinth and poss a hadcock or other u/p to do plus a replacement Phono pre as my Lite Audio mush-monster is letting the side down with out Philips Denon Step-up's. I'm waiting to see how the WD Phono3 works out with other guys on the WD BB before shelling out.

DTB
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