Deacy Amp (?)

[Ivana]

I think that "3.5:1+1" is not Rp and Rs are DC resistances but a relation ("/" ))) of the... coils? spirals?...  my bad english...

[R.G.]

The "3.1+3.1:1" is the voltage (and turns) ratio of the windings. If you put 1V on the "1" winding, then 3.1V will appear on each of the other two.

The Rp and Rs numbers are indeed the DC resistance of the copper in the windings. This has little to do with the turns ratio or impedance ratio.

The impedance ratios are yet another way of describing the same transformer, and possibly more useful. They describe what impedance appears at the primary winding if the specified loading is applied at the secondary. That is, the "1.2Kct to 3.2ohm" specification promises you that if you put a 3.2 ohm resistor on the secondary, then whatever drives the primary will think it's a 1.2K ohm load.

The turns ratio and impedance ratios are related. The impedance ratio is the square of the turns ratio. So in the case of a 3.1+3.1:1 transformer (voltage) you'd have a
(3.1+3.1)squared to 1 impedance or 38:1 impedance ratio. If the load is 3.2 ohms, then the primary load is  121.8 ohms.

The real "doesn't make sense" in this case is that the voltage ratios and the impedance ratios don't relate by the squared function.

[christiancm]

Hello everybody,

OK Ivana, it's very  interesting but what is the impedance values of the OC81D and voltage or impedance values for the T1 along with power ratings for both transformers ?

[Ivana]

I think that "impedance values of the OC81D" is not exist as a parameter. It is not a pentode. The main aim is to preserve the power overloading of the transistor.

[rotylee]

does anyone know where this diylc file might be?
http://diy-fever.com/wordpress/wp-content/uploads/2012/08/component_layout.png

[Kipper4]

Also check out knight audio technologies Deacy amp. This is the kit I bought and was my first DIY project last Christmas and I haven't stopped learning since

[rotylee]

Kipper4 :
did you get the trannies there.? they seem a little steep. 
are they different what most are using for this kinda app.
>>>
WARNING! There are a number of third party transformers for sale on the internet. Some are configured incorrectly with the primary coils of the interstage transformer reverse-wound. In this instance, the amplifier will not work correctly untill you swap over the primary connections. A number of these transformers, and some claim to have been tested in the actual Deacy circuit, are also of the wrong turns ratios, which, causes too much gain within the amplifier stages.
>>>
an ok deal on PCB and components  though.
are they geranium transistors?



 

[Kipper4]

No i did not use the transformers sold by KAT. Yes they are a little steep but i wish i had used them now.
I used some bought from ebay in eastern europe.
Any yes they are configured differantly i had to swap 2 legs over on the transformers.
it sounds good but i think it could do better with better qaulity built transormers. IMO.

[greaser_au]

No i did not use the transformers sold by KAT. Yes they are a little steep but i wish i had used them now.
I used some bought from ebay in eastern europe.
Any yes they are configured differantly i had to swap 2 legs over on the transformers.
it sounds good but i think it could do better with better qaulity built transormers. IMO.

Rich,

just out of interest:  what did you use for a speaker/cabinet?

david

[Kipper4]

I had an old hifi (6" speaker and 2" tweeter) in the loft from an old 8 track my wifes father passed onto us.
I used it because i wanted that small speaker thing that mr May did with his.
I took the back off and put the circuits inside and screwed it back on.
I say circuits because i also built the KAT direct record/headphones circuit and an integrated treble booster.
The treble booster was an old supposedly brian may treble booster traced one unfortunately its ground positive so i have it supplied by a battery that clips on the back of the cab.
i put plugs to go in and out of the treble booster and an amp direct jack too and use a short patch cable on the back to put the treble booster in line.
A friend did a simultanious build and used a single wallwart power supply for both amp and treble booster but used a max1044 i think it was to reverse the grounds for his treble booster but he had a lot of problems with it before he did a similar thing to me and gave them there own power supplys as they didnt want to play well together as he had them.
I also have the possibilty to use a pp9 battery supply for the amp (lead sticking out the back of the amp) Should i ever decide to take up busking.

[happytreefriend2004]

The Fryer Sound Deacy Amp sounds really amazing and it is so close to the sound of a good tube amp.
Check out my demo here:
https://www.youtube.com/watch?v=PnNJfHTxliw

[Kipper4]

Nice sound. I wish you had played with the guitar volume though.
I guess your not using a treble booster since you say no effects then?
Those pups sure sound good too.
Sweet
Rich

[happytreefriend2004]

Thanks, see the second part from Clean to Overdrive by just rolling up the volume guitar pot below (there is no treble booster):
https://www.youtube.com/watch?v=CjHgcS4tPqQ

[Kipper4]

Did you get the fryer transformers in there too?

[happytreefriend2004]

Yes there are two Fryer transformers in the circuit.

[happytreefriend2004]

Sorry for the broken links, please find my demos of the Fryer Sound Deacy Amp here:
https://www.youtube.com/watch?v=zQ5xuR0N_fo
https://www.youtube.com/watch?v=o8VL64gORKw

[Rob_Lo]

Hi,

I am looking into building a Deacy replica from Paul Stevensons stripboard layout.

https://paulinthelab.blogspot.com/2012/06/brian-may-deacy-amplifier-stripboard.html?m=1

He states this is based off of Greg Fryers design...but wasn't Fryer the one who developed the KAT build along with Nigel? Because this layout is much different than the KAT schematics (which looks similar to the original mullard layout). Either way there seems to be much misdirection and misinformation surrounding the legend.

I didn't want to use the Eagle transformers because their output seems a but low. And I have i ohm drivers lying around so I settled on the Xicon trannies from Mouser..which are still significantly lower output than the 1w specified

http://www.mouser.com/Search/m_ProductDetail.aspx?Xicon%2F42TU048-RC%2F&qs=LQJGOuQCHKR6gBOQxy1apw%3D%3D

http://www.mouser.com/Search/m_ProductDetail.aspx?Xicon%2F42TM024-RC%2F&qs=%252bLh6ltJumVS5xwocZBTZJg%3D%3D

My question (forgive me I'm green and still learning)....does the topology of the layout have to change? Or are trannies with similar specs interchangeable

[nickbungus]

Hi.  Could you please share the links for the Mullard and the KAT?

[greaser_au]

Hi.  Could you please share the links for the Mullard and the KAT?

Knight Audio : http://www.deacyamp.com/    have a look under the 'Project room' for the Deacy-style amp stuff, there's a few downloads... The amplifier kits and transformers seem to have disappeared from the shop pages though, so possibly they might not sell them any more...

david


*edited for clarity

[digi2t]

FWIW... I built mine with the transistor set from Ebay, and the Eagle transformer set from Ebay. Actually only used the first two transistors from the Ebay set (AC125 / AC126), opting for a matched pair of AC128K's that I had on hand for Q3/4. Used the schematic from the Vox Deacy, along with a Fryer boost on the front end.



http://www.diystompboxes.com/smfforum/index.php?topic=105657.0



I had to build  +/- power supply onto the board to deal with the NPN/PNP deal, but no big deal. The most important element after the circuit is the speaker. I tried three different 8" whizzer cone speakers, and I found that the cheapest paper cone you can possibly find, is the best. Paper throughout works best. I tried one with foam edging, and it was totally wrong. It just doesn't project the midrange frequencies properly.

For missing web pages, if you have the page address, try the Wayback Machine. You might get lucky.