Raphaelite DP84 EL84 Push Pull

[mroboto]

Hello,

I own this full tube amplifier for four years now and very pleased to have it.

It's hand made in China

I have made some mods,

Added 2 thermistors CL-80 / NTC 47D-15 on the PT , one on the primary 120V tap and one on the 280V secondary. CL-80 and NTC 47D-15 are the same except fotr the price and precision.

Replaced 2W10M bridge for UF4007 diodes.

Added 2 CBB 2.2uf 630V decoupling caps to main supply cans.

Replaced some resistors, choosed 1W AB carbon comp, but i not really recommend, it's a lot of work matching resistors and the pcb holes are to tiny for the big leads of 1W CC need to thin them with a grinding wheel, and i thint that have very minimal incidence on sound quality.

Replaced (Good) El-Menco 0.082uf 1000V coupling caps for (other Good) 0.1uf 1000V K40Y-9, and recently for (better) Mundorf Silver Gold & Oil 0.1uf 1000V

After mods picture:



The Stock power tubes runs for 4 years, more than 12 hours a day, and still test like new tubes on my calibrated Sencore Mighty Mite VII TC162

The RCA 5Y3GT rectifier that is as old is on it's end, don't pass the life test, but i have others and a Weber WY3GT copper cap in case i want to listen to a solid state rectifier.

The rectifier seconds the diodes in the chain, acts more like a soft-start and tube buffer than a rectifier.

I realy like most of the 12AX7 preamp tubes i have listen to. It's easy and pleasant to listen whatever i choose.

Hope to buy other of these tube amps in the future, maybe to make bi-amp or surround system.

Listings resently have been removed on eBay for this amplifier by sellers, Hope they will come back...

If you need the schematic, the seller gave it to me, i made a hi-rez jpg from the original pdf

http://speedy.sh/Fa3y2/Raphaelite-DP84-Schematics.jpg

And uploaded the pdf version to AudioKarma

 

[Kegger]

That's a very nice, and neat looking little amp, the output and power tranny covers look very similar to Sansui.

I notice the outputs have UL taps, might be fun to experiment an hook them up. (also a 5V4 in place of the 5Y3)

Cheers and congrats!

 

[Poultrygeist]

Nice. I keep reading good things about Raphaelite transformers.

 

[Palustris]

You are correct in that the 5Y3 does nothing except provide a "soft start" so there is no point in using Weber WY3GT since you already have solid state rectification. That would seem to render the two thermistors superfluous.

 

[mroboto]

You can buy the Output transformers separelely on eBay, just type OP9K10AB

Don't know if transformers are made of permalloy , maybe not, they don't tell about this model, but they made Permalloy core input or maybe phono transformers.

Edit:https://en.wikipedia.org/wiki/Permalloy

I used it for 3 years without thermistors, but i noticed a blue flash in some rectifiers each time i turn it on, not all,, no big worry about, but i feel a little unconfortable, i expect my RCA 5Y3GT rectifier to last more than 3-4 years, as it becomed worn testing now.

Since i have installed Thermistors, the flash tammed, not completely disapear, but was worse before.

The Weber copper cap is just a drop in, sounds a very little bit different, tubes have a tendency to smooth current flow compared to SS rectification i think

But Weber will never fail...

 

[derekva]

Very clean looking. I'll bet it sounds nice.

-D

 

[mroboto]

It sounds just right, natural and relaxing, i like all 12AX7 i have try,

Stock 12AX7 was NOS Sovtek 12AX7WA , i given them a listen recently, clean and clear, not soft and neutral as RCA long Black Plates but very good.

Not tube rolled EL84 much, i have some, but keep some as NOS, just tested, as amp was already equiped with good output tubes 6P14P-EV from 84'

Different sound than my Yaqin MS-300C , i tuned both the best i can, but the bias adjust thing that always drift and the 300B that cost more than 300$ a pair for good, and Yaqin absolytely require very good drivers and preamp tubes to sound righ, like Mullard 12AT7 (With 3 holes) and Sylvania 50' T plates 6SN7GT's, And the Yaqin kills his rectifier 5U4GB in a few weeks, replaced with a weber, definitely.

The Raphalite is my #1 daily driver, the Yaqin is second, also listening Sansui sometimes.

I own multiple Sansui's and the Yaqin before the Raphaelite and in the beginning, the Yaqin was too bright and analytical sounding, until i found the tubes that made it sounds more appropriate with my modified Paradigm 7SE speakers that are very neutral to begin with.

The Yaqin is very detailed, sometimes too much in the upper range, the Raphaelite is more natural and relaxing tone.

 

[Poultrygeist]

I like the fact that Raphaelite is a transformer company that also makes amps. Many of their tranny's are permalloy.

 

[mroboto]

I think that maybe my transformers cores are in permalloy, and they keep that as a manufacture secret, they sound excessively great so they must be

They are potted in appearance, maybe really, and looks like their other but smaller, for input signals Permalloy products.

 

[mroboto]

I just asked doukmall (ebay seller) and he reply me: the output transformers cores are in permalloy on this model

 

[derekva]

Different sound than my Yaqin MS-300C , i tuned both the best i can, but the bias adjust thing that always drift and the 300B that cost more than 300$ a pair for good, and Yaqin absolytely require very good drivers and preamp tubes to sound righ, like Mullard 12AT7 (With 3 holes) and Sylvania 50' T plates 6SN7GT's, And the Yaqin kills his rectifier 5U4GB in a few weeks, replaced with a weber, definitely.

You might want to try replacing the 5U4GB with a 5931 as it can handle a higher MaxPv (600v) and MaxPmA (300A), but has virtually the same voltage sag (47v) as the 5U4 (50v) and the same heater amperage draw (3.0A). Alternately, check the value of the first cap after the 5U4 in the Yaquin (can't find a schematic to check this - sorry). However, if it is too large (e.g. bigger than 30uF or so), it will eat rectifier tubes.

-D

 

[mroboto]

Yaqin MS-300C have a lot of capacitance, but uses a choke.

If you want the schematics: http://speedy.sh/APYK7/Yaqin-MS-300C-Schematics.jpg

That was a NOS Philips , Sylvania made i think, that becomes bad very quickly.

Thanks for the 5931 suggestion instead of 5U4GB.

Edit

But i think i will not risk on other tubes.

The Weber Copper Cap WU4GB do the job for the Yaqin.

The Raphaelite don't have problem with tube rectifiers, here i use tubes.

 

[mroboto]

Pictured in action, he is sitting on a Sansui AU-9500 that is sitting on a chair, i have too much other Sansui , Yaqin and other equipement in the shelf right now...

Have a Bendix 6106 , 6P14P-EV and RCA 12AX7 long black plates under the shields.

The 12AX7 shields are not the sheilds i got with the amp, the original are more textured aluminium, was searching fot more chromed ones, i have found, not perfect, but after a Brasso, this looks clean.

 

[Poultrygeist]

If I were to buy a 300B SET I think it would be this Raphaelite. They go for slightly under a grand plus shipping. I've seen some on eBay with a "make best offer" and I wouldn't be surprised if you could get one for $700 or $800.

 

[mroboto]

They are not cheap, but it's for sure quality products.

I found the Yaqin 300B SET to be not as relax sounding than my PP EL84 , i found the term relaxing more appropriate, with good tubes choices both can make magics.

 

[mroboto]

If you buy, ask for the schematics.

And do as i do, to be safe, take a picture of the under of your amp and note every part value of resistor, capacitor you find using Windows paint on the picture.

I got no trouble with the amp but a trouble when i inserted a bad tube, nearly took out a resistor, resistor color changed after smelling this and turned of the amp, that particular tube was very hot to touch, resistor was easy to replace.

That was one of tne 3W 270ohm Metal film cathode bias resistors on the top left of the picture.

Replaced them with 3W Carbon film.

 

[mroboto]

The Yaqin 300B have 12AT7 -> 6SN7 -> 300B (more tubes in the chain)

The Raphaelite 300B have 6SJ7 -> 300B

I'm sure the Raphaelite is better, everything taken in consideration, except the Yaqin is remote controlable.

My DP84 also have less tubes in the chain, i think the lesser the better the signal is direct.

Edit:
But The Raphaelite 300B use uncommon regulator tubes (WY2P).

Edit2:
I have found what i think is cross references or close 0A3 CV1895 CV3798 QS1205 QS75/40 CГ2C

 

[mroboto]

The only thing i don't like about the Raphaelite, is the 4/8 ohms switch between output transformers and output binding posts.

This is a good quality switch from what it seems to be, not very big but not a cheap very miniature one.

If that switch contact becomes intermitent, that could be dangerous for the output transformers, i got noisy faded output once, flick the switch and everything was ok after, so i realise that could be the culprit for possible serious failure.

Easy to switch output in the flick of a switch to compare 4 and 8 ohms, but i wondering if it's dangerous for transformers when done at low level output, to have some microseconds without load on the output transformers at low listening levels, do you think ?

I don't flick this switch frequently, will probably need contact cleaner one day...

 

[ferninando]

I want a ralphie

 

[Tom Bombadil]

Nice amp. When one considers that spending $161 in 1970 is the same as spending $1000 today, then you realize what a great value some of the Chinese amps are.

Question about the Weber WY3GT, why does Weber advise against using this in a Hi-Fi amp? Clearly you have chosen to disregard that warning.