FS: Jolida SJ/JD-502a Integrated Tube Amplifier

dorokusai

Jolida SJ/JD-502A Integrated Tube Amplifier - 9/10 - Black - *SOLD* to Bikerboy

I picked up another Jolida gem in my travels but as usual, have absolutely no real use for it. The amp was demo'd in house on my 2CH rig, running pairs of Triangle Titus, KEF C15 and Reynaud Twin Mk2. They may have been simple monitors/bookends but with varying specifications, it drove them just fine. I had alot of fun playing with these combinations.

This is a rock solid way to get into tubes and you have the benefit of it being an integrated amplifier, for easy plug and play operation. The 12Axx tubes have <80 hours on them and include NEW Svetlana 6550C power tubes with <35. You can bump these up to KT88 for fun or more dynamics. I think the "Winged C" sound great from the gate. The front end are Sovtek 12AT7 and 12AX7, which is standard fare for pre-amp and driver stages in most gear these days. It's a very common tube so you can do all kinds of tube rolling if that's your wish.

The finish is a black metallic flake and reminds me of the metallic finish you see on river or speed boats, if that's gives you an idea. It's not really my cup of tea but it's a deep, reflective finish that you can clearly see in the pictures. It also has the upgraded binders and front panel knobs. The standard knobs are black, these are gold/metallic black to match the chassis.

The unit has been throughly dressed and all connections have been treated with CAIG products. The white specs on the iron is simply from the paper towels used to wipe them down, they are flat/semi-gloss black and spot free.

EXTRA'S!!!

The unit has the factory subwoofer output option(AUX), which at the time was a $150 option. I've also added aftermarket Dynamat damping to the inside of the chassis and bottom plate.

I am including a brand NEW quad of Electro-Harmonix(2-12AT7/2-12AX7) for immediate tube rolling.

A matched pair of 1960 RCA, short plate, halo getter 12AX7. You can immediately listen to some old school tube lineage.

In addition, a brand new set of pure silicon(white) tube dampers(8) for the 12series tubes.

Here are some specifications:

Maximum Power Output: 85 W per channel at 8 ohms, 1KHz
Rated Output Power: 60 W per channel at 8 ohms, 25Hz-60KHz Frequency Response: (at 1 watt into 8 ohms) 8Hz-130KHz +1dB Bandwidth: 15Hz to 80KHz + 3dB; 0dB 60 W 1KHz
Distortion THD: Less than 1% at 20 V output, 28Hz to 15KHz Circuit Type: Ultra Linear, Class AB Input
Impedance: 100Kohms
Input Sensitivity: 600mV at 1KHz for 60 watt output
Output Impedance: 4 ohms and 8 ohms
Negative Feedback: Less than 5 dB
Noise and Hum: 85dB below rated output
Tube Complement: 2 matched pairs (4) of 6550/KT88 power output; 2 pcs. 12AX7A/ECC83 pre-amplifier; 2 pcs. 12AT7/ECC81 power drivers.
Dimensions: 17" wide by 15" deep by 7.5" high.
Weight: 48 pounds net, approximately 52 pounds packaged. Warranty: 2 yr limited parts and labor. 1 yr or 1000 hours whichever comes first on Jolida Tubes.
Bias Settings: 50 millivolts + 5 mV

Includes: Original box, original packaging, original power cord, original user manual(RARE! ) and factory schematic. The unit includes shipping and will be internally double walled for protection.

This unit, and its little brother the 302, are easily modded by the DIY type. Check on the internet for some goodies and break out the soldering iron. If you're not the type, let's talk as I'm pretty familiar with the Jolida products.

Thanks for reading!

JSJ502675

bikerboy

Hi,
I am interested in the amp. I need to run it by the "boss" and will let you know in a couple of hours. This should make the sda-2 sound great!Thanks, Jeff

dorokusai

Jeff,

No problem. Let me know if you have any additional questions or comments. Thanks for the interest either way.

Mark

madmax

Not interested in the amp (because I already have one) but was wondering if you are familiar with the "sub out" functionality? Is it a volume controlled full range output? Does the schematics show how it is connected? Been thinking for awhile it would be nice to add one to mine.
madmax

dorokusai

madmax wrote: »

Not interested in the amp (because I already have one) but was wondering if you are familiar with the "sub out" functionality? Is it a volume controlled full range output? Does the schematics show how it is connected? Been thinking for awhile it would be nice to add one to mine.
madmax

The schematics do not show the subwoofer output. From my understanding its a pass-thru, much like an HT bypass would work. It shouldn't be used as a source connection as its wired differently from the I/O stage. You would probably get a less than desireable condition, whether its feedback or transformer hum if you used it as anything but an output.

If I get motivated tonight I'll pop the hood and see if I can trace the wires. I would imagine its fairly straightforward but it wouldn't be the first time I've been proven wrong when it comes to circuit design. I'll snap a couple pics.

bikerboy

Hi Mark,
I want to get the amp. Just to be sure, it is common ground isnt it? PM me with details and I will send the moneys your way. I dont mind if you pop the top to help out madmax, I will be doing the same myself just to see what it looks like. More fun with tubes!!! Thanks, Jeff

madmax

They are most definitly common ground. I checked mine out because I use it with SDA's.
madmax

dorokusai

Madmax - The best I can gather, without complete disassembly, is that the aux input is wired normally, all the way into the pot. At that point it gets a jumper(white), and piggybacks the main output(black-green/yellow) wires, from the pot, to the main PCB.

If that's the case, and I'm not positive, then it would make sense that it provides feedback or hum to that output.

dorokusai

bikerboy wrote: »

Hi Mark,
I want to get the amp. Just to be sure, it is common ground isnt it? PM me with details and I will send the moneys your way. I dont mind if you pop the top to help out madmax, I will be doing the same myself just to see what it looks like. More fun with tubes!!! Thanks, Jeff

Awesome! Thanks much. Sorry for the late post, as Madmax had me intrigued about the subwoofer output.

Anyways, as MM stated previously, it is common ground and ready for any SDA.

If you do go DIY, its a dream to work on and I would bet it was designed to be upgraded.

Please send me an email and we'll wrap everything up... dorokusai@comcast.net

Mark

madmax

Cool deal! So it does go through the pot for control. I'm guessing it comes out to the jack right where the controlled preamp signal meets the amplifier stage. It makes sense anyway.
Thanks!
madmax

reeltrouble1

excellent, nice grab bikerboy.

nice FM deal.

RT1

JimBRICK

very nice piece, just too poor to ante up myself right now

bikerboy

Hi Doro,
The money is on the way. Cant wait to see those fat tubes glowing. I have been looking at the diy options. I might bypass the pre amp section and use the amp section with my TAD-150. But I will listen to it for a while before I do that. Fun Fun Fun.

dorokusai

Cool...I'll let you know when its on the way. You should definetly play with it for awhile before you start experimenting That sounds kinda dirty and personal.

bikerboy

Hi Doro,
The amp arrived safe yesterday afternoon. But if I use the sda ic I get a hum and it sounds congested. Without the ic sounds good. Whats up? I checked continuity on all wires and they are ok. Even swapped the diy cat 5 wires out and if I connect the sda ic the hum and congestion comes back. But the ic is a cat 5 also and will have to solder a different wire on the ends to swap it out. Any ideas? I think I will go for a mtn bike ride for now and deal with it later. Thanks.

dorokusai

Excellent. I was running the amp on a pair of SDA1C with no hum or congestion.

I would suspect your DIY CAT5 first. Do you have a generic pair of patch cords? What SDA speakers are you using?

You can email me if you want.

madmax

I used my 502 with 1C's and all the other variations of SDA's with no problem, both the 4 and 8 ohm outputs. Check to be sure your IC cable is not wired wrong and that you have both (-) of the amp going to both (-) of the speakers. This problem could be created if you used the wrong connectors on the amp. For example, 4 ohm to (-) and 8 ohm to (+) or vice versa.
madmax

MillerLiteScott

You may also have a ground loop problem. Try using a cheater ( two prong ) plug. See if that eliminates the problem or it may be interference from other electronics.

bikerboy

Hi,
I carefully stuck a piece of 16 ga wire into the blade-blade sda-2 ic jacks and no noise. Now it sounds great. The top end is very nice, not as in your face as the B&K and the sda sweet spot is back!. So I will reinstall the cat 5 speaker wire with the 16 ga ic later and see if the hum comes back. I knew it should work with these speakers! Oh yea wires dont make any difference! Dont even start. So all is good except I need new speaker wires. Thanks and back to your regular programing.

dorokusai

I'm happy you found the issue and are in LALA land Use whatever interconnects you want, that argument doesn't even interest me anymore. My comment was moreso on the DIY portion of the cable, not the sonic properties.

On a side note.....I found the tube dampers. Since I have a healthy collection, what size do you want? I have 3 sizes - SM - MED - LRG. Also, the tubes are on order since I must have used the others in a project. I'll ship everything at once if you don't mind.

Thanks,
Mark

bikerboy

Hi Doro,
I switched back to using the cat 5 speaker wires with the 16 ga wire as an interconnect between the speakers and no hum. So I am all good. As far as the dampers, I guess the 12xx7 size. I dont think using them on the 6550 tubes is that important, but I dont really know. It seems that they would help the most on the smaller tubes. I am just happy the bugs have been worked out. Shipping all the stuff at once is good. Thanks again for the great amp.

marvda1

i just got in a jd 502b and it is a great sounding amp.

madmax

Hey, just ran across something in my mind that happened to me way back. I had used my system for quite some time and all of a sudden it started humming. It turned out to be a speaker wire was somewhat loose on the (-) terminal of the amp. Never really did figure out exactly why this would cause a hum but it did.
madmax

JimBRICK

bikerboy I have dibs if you sell

bikerboy

Hi Jim,
Dont hold your breath! I wont be selling this for a long while. It sounds great and from what I have read about the diy mods available it can sound better. I have removed the preamp (input, volume, and balance pots) and am using the TAD-150 as a preamp. Big improvement. But I will continue on the 2 ch forum. Thanks again Doro.

bikerboy

Hi Mark,
Just checking on the tubes for the jolida. I sent a message to your comcast email and it was returned undeliverable. Thanks.

dorokusai

Hey, sorry. I forgot about this completely. I have the dampers, just need the tubes. Here's my new contact information:

dorokusai@verizon.net