DVD-Software.info

[Steve H]

Hi,

I have a pair of Danbury elect output transformers, I am told that they are
from a mullard 520 amp, are they any good? and will they work with a pair of
6L6's??

--

Steve H




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[izozaya]

The ones you have were used by Maplin Electronics in their Mullard
5-20 kits.

Please note that neither these kits are vintage at all nor they are
exact clones of the Mullard design (they feature silicon
rectification). Still these Danbury trafos are pretty good. I have a
couple of them, bought from Maplin about four years ago, in a
Push-Pull 4654 amp - really nice sounding.

In your amp, a couple of 6L6 in push-pull will run fine, plus you can
always migrate to EL34 easily.

Regards,

Ignacio

"Steve H" <me@spamcpstelecom.co.uk> wrote in message news:<41a4f374$1_3@mk-nntp-1.news.uk.worldonline.com>...

[Andy Evans]

I've used the Danbury Maplins 6.6K and also the bigger version of it (was sold
by Maplin as an upgrade). The current Maplins one (smaller) is more detailed
but the larger one has a fuller tone and better bass. They're both fine - no
worries. I've also seen a fr. graph which is very smooth.
Just a question on the 4654 - I have some, of different kinds. Basically EL50s
but mine are either octal base or P base. what's your experiences with these
rare tubes? I have a few EL50 plus some EL39 as well. (and a quad of EL35 but
that's rather different). Andy

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

[izozaya]

Hi Andy!

All the 4654 samples I happen to have are just like metal base EL34's
but with a P socket (AKA Transcontinental) and the top cap (plate).
However though, plate dissipation is a bit lower (18W). My experience
is very good overall, but needed quite a lot of trial and error before
achieving a satisfactory performance. The final recipe features fixed
grid bias, triode connection, and 375V/50mA operating point. Around
12dB of negative feedback helps keeping the bass tight and controlled
without noticeable effects in the higher frequencies.

Best regards

aeatartsandmedia@aol.comnohawker (Andy Evans) wrote in message news:<20041125092856.00480.00001013@mb-m17.aol.com>...

[Jim McDonald]

"Andy Evans" <aeatartsandmedia@aol.comnohawker> wrote in message
news:20041125092856.00480.00001013@mb-m17.aol.com...

[Andy Evans]

Over the years, Dave Brooks/Danbury has done me a number of 'specials' He's
also done me OPT's ... 50W 3.8k and huge 100W 5ks ... Jim in Stoke on Trent >

I have 3 amps with the same input circuit - 2C22 into 12b4 concertina into the
output stage. With 7591s the larger stack 6.6K was fuller in tone with more
bass, while the current Maplins 6.6K was more detailed. With EL84s the current
6.6K was better than the OPTs on the Leak Stereo 20 - cleaner all round and
more detailed. I was surprised it sounded so good with EL84s - I just put them
in as a stopgap for EL86s when I take the B+ down a bit, but they may just stay
in there. The bottom line is that for £29.99 the 6.6K Maplins OPT is an
absolute bargain. They clearly got the design right on this one. Add the
Maplins mains trannie at £29.99 and throw in two chokes at £6.99 per monoblok
and you have all your iron for £73.96 per monoblok. Now that's seriously good.
Staying with Maplins, add some LCR motor run polypropylenes for the PSU, and
use a hybrid bridge with some damper diodes like 6BY5G or 6DT4 (6AU4 etc) all
off the same 6.3v supply and you have a very serious pair of amps. All you then
have to do is phone Edicron for some 7591, 2a3/6B4G Sovteks, 6N30s, use Allen
Wright's cascode front end and you should have a true audiophile amp for
peanuts.

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

[Steve H]

Thanks all,

It looks like they are the maplin version, I've built one monoblock and
using 6L6G's it sounds good, but I have just tested it with 350B's and the
detail is amazing. All I need now is another pair of 350B's for the other
side :c)

Steve H
"Andy Evans" <aeatartsandmedia@aol.comnohawker> wrote in message
news:20041127053954.08238.00001280@mb-m04.aol.com...

[Wbittle]

Hi,
The Mullard 5-20 was a dual EL34 push pull cathode biased amp. It was
rated at 20 watts, but could produce close to double that with only 1.2%
distortion. So, this transformer should handle any amp up to around 35
watts. The 5-20 called for an ultra-linear 6600 ohm plate to plate
resistance output transformer. These should not only have the two plate
taps and the center tap, but two 20 - 40% screen taps. These will work
great with the 6L6. Try to keep plate and screen voltage to 450v or less
for the 6L6 and it should work great. In fact, I built a 5-20 as my
first amp project back in the dark ages when I was a teenager. The 5-20
will work with either the EL34 or 6L6 and deliver quite good results.
Bill B.

Steve H wrote:

[Ruud Broens]

"Andy Evans" <aeatartsandmedia@aol.comnohawker> wrote in message
news:20041127053954.08238.00001280@mb-m04.aol.com...
<snipped very informative stuff from Andy here>

: === Andy Evans ===
: Visit our Website:- http://www.artsandmedia.com
: Audio, music and health pages and interesting links.

Hi, Andy. Have you given the 'telco tubbies' a tryout yet :-) ?
Hope to finally sniff some solderin'fumes next year, just
too busy atm.
Greetings from across,
Rudy

[Andy Evans]

Remind me which were the Telco? ECC40? If so - not yet. Greets, Andy

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

[Ruud Broens]

"Andy Evans" <aeatartsandmedia@aol.comnohawker> wrote in message
news:20041202052658.06500.00000885@mb-m22.aol.com...
: Remind me which were the Telco? ECC40? If so - not yet. Greets, Andy
:
: === Andy Evans ===
: Visit our Website:- http://www.artsandmedia.com
: Audio, music and health pages and interesting links.

The loctals, 5B /110M,
Rudy

[Andy Evans]

The loctals, 5B /110M,
Rudy

Ah right! No - I should try something - maybe trioded? How have you been using
them? Andy

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

[Ruud Broens]

"Andy Evans" <aeatartsandmedia@aol.comnohawker> wrote in message
news:20041204090817.23235.00001630@mb-m03.aol.com...
: The loctals, 5B /110M,
: Rudy
:
: Ah right! No - I should try something - maybe trioded? How have you been
using
: them? Andy
:
: === Andy Evans ===
: Visit our Website:- http://www.artsandmedia.com
: Audio, music and health pages and interesting links.

Hm, gotta confess, got a bit bored getting trioded curves, *am* a bit of a
freak, like getting the gridvoltage withing 1 millivolt with each 'take' :)
but as far as i got, they looked fine, 250V 40 mA a good start.
Bye
Rudy