JBL/UREI 6290 and 6260 Amps

[Ken Pachkowsky]

I have never heard the above. Anyone have any experience with these amplifiers? If so what were your impressions. Thinking of grabbing a couple of them.

Thinking of using the 6260's in mono mode to drive dual 2235H's per side. 4 ohm load. Would be 600 watts per side.

Thanks.

[speakerdave]

Hey Ken,

I've been thinking along the same lines, but I haven't had a chance to check them out. Be aware that the 6290 has a two-speed fan, so you'll want to be using that in an environment where that is OK. The 6260 has a large finned heatsink at the back and no fan.

These amps seem to have a very solid build quality and are available at what seem to be very reasonable prices.

I'm thinking of them as bass and bass/mid amps, or full range in a simpler setup.

David

[sa660]

The 6260 is very good amplifier and you will see that their is no fear that your dual 15" will be out of control.
My brother is using a 6260 on a pair of 4435. He does not feel the need to bridge it for mono mode 1x600Watt @8 Ohms.
They are very good and can be compare to the Amcrown DC300 II

Unfortunatly cannot compare with expensive high end Hi-fi model.

May be in future.

Good product and on the second hand market good value for money. I will not advise the 6290 for home use. The fan is very noisy.

Regards,

[Niklas Nord]

A friend of mine here in Sweden uses these
models for amping 2235H and 4435 studiomonitors.

it works perfect.

right now he is upgrading to Krell KSA 250 though..

[JBL Dog]

I have three of the 6290's and they are outstanding amplifiers, IMHO. Very clean sounding, conservatively rated and reliable. One of the few amps on the market that you will actually double your power output going from 8 ohms (300 x 2) to 4 ohms (600 x 2). I am currently using mine with some EV SX100's full range for small club gigs and as part of of tri-amped system for mids/highs.

You may not like the fan noise as previously mentioned, but a 6290 may be the best value on the Ebay market at $250 - $350. They're pretty heavy at about 70 lbs. Factor that in if you are having them shipped to you. Good Luck!

This message comes from JBL Dog :band:

[Ken Pachkowsky]

I appeciate your input fellas.

Building a custom pair of 4355's and am shopping for new electronics.

Let me throw this out for opinion's:

Should I go quad amped with 4 way electronic crossover or bi amped with combo electronic and passive using higher end amps?

I suspect most would suggest bi amped with better amps?

Ken

[JBL Dog]

I would go biamped. Quad sounds like too much work. Also, wouldn't you be forced to go mono with quad? Does anyone make a "stereo" 4-way active crossover?

:hmm:

This message comes from JBL Dog :band:

[Ken Pachkowsky]

There are many 4-way electronic crossovers out there. My Westlakes are 4-way. The problem becomes groundloops if mixing balanced and unbalanced lines. I still have a slight GL problems to this date. You can of course have the same problem with a 2-way system.

[boputnam]

Originally posted by Ken Pachkowsky
Should I go ... bi amped with combo electronic and passive using higher end amps? Hey, Ken... :wave:

Since you're largely trying to authentically replicate the 4355's, I'd do it their way: active crossover bi-amped, and then passive crossover for MF/HF/UHF, using JBL specified xover points and slopes, and bypass caps. Mr. Widget made a beauty passive with the assistance of Giskard (and others...?), and his "rig" is astonishing.

Although, I hear tell he's adding some 2245H's for the rumble... :hmm: I think it's 4345 envy, plain and simple! :yes:

[Robh3606]

Hello Ken

I am quad amping using cascaded actives works fine. I had ground problems too then I changed amps to all Crown PS200's and got the balanced input boxes for them. As soon as I went balanced between the amps and the crossovers all my ground loop problems vanished. Made a big improvement in noise in the whole system. Didn't realize at the time how much noise I was living with that I just got used to. Cleaned up noise in my center channel too.

I would go biamp with a 5235 like Bo says. Experiment too maybe but that sure makes sense. When choosing your amps I tried to get amps I could stap easilly. With the Crowns I can strap with the flip on a switch. 2 strapped for the lowend and use a single for the highs for biamp or triamp. Gives you more flexabillity.

Rob:)

[Ken Pachkowsky]

Originally posted by boputnam
Hey, Ken... :wave:

Since you're largely trying to authentically replicate the 4355's, I'd do it their way: active crossover bi-amped, and then passive crossover for MF/HF/UHF, using JBL specified xover points and slopes, and bypass caps. Mr. Widget made a beauty passive with the assistance of Giskard (and others...?), and his "rig" is astonishing.

Although, I hear tell he's adding some 2245H's for the rumble... :hmm: I think it's 4345 envy, plain and simple! :yes:


Well, as you know BO, I understand 4345 envy quite well.

I have always thought I would go bi-amped with a custom passive built by Widgy but was just getting some other opinions.

Earl also brought up an interesting point in one of the project threads. Why not incorporate some newer JBL technology in terms of drivers for a 43xx project. That got me to thinking.

Just did our taxes.....Julie saw what I spent last year on all this stuff. I hate the couch!!!

Gonna be fun.

Hope you and Susan are well. Julie says Hi.

Ken

[Mr. Widget]

Next I am buying a Hummer.


What's that Mike, Big is Good?

[boputnam]

Originally posted by Ken Pachkowsky
Just did our taxes.....Julie saw what I spent last year on all this stuff. :shock: Are you trying to deduct all this as a business expense? Whoa... Come to papa! :dancin:

[Ken Pachkowsky]

Originally posted by Mr. Widget
Next I am buying a Hummer.


What's that Mike, Big is Good?


Speak of the devil!

Whats this " You have 18 inch envy all about?

Ken

[Mr. Widget]

Not exactly, got a pair of 2245s for the HT set-up. At the rate I am going it'll be a year before they are in boxes. I can click "Buy it Now" much faster than I can keep up in the shop.

[Oldmics]

I hear that disease is called "Trigger Finger"
Oldmics

[Tom Loizeaux]

Ken,
I use a 6260 and a 6230 in a bi-amp rack, along with a 5235, to drive one of my studio monitor pairs. I also have a similar set up using a Crown PS-400 and PS-200. I find the JBL/ Ureis to be a bit stronger (louder) and sound fine, but the Crowns seem to have slighty less noise and seem a little more refined. ? I believe the protection circuits in the Crowns are a little more advanced.
I like all of these because they are big, heavy, stable and overlooked by most people today.

Tom

[Ken Pachkowsky]

Thanks for the info guys, will let you know if I get them.

Nice to hear from you Tom.

Ken

[Mike Caldwell]

Hello
The largest Urie amp had speaker sense line input jacks
in the form of BNC connectors.
These were for and second set of lines going to the
speaker and connecting to the main speaker cable binding post
or connectors.
The amp would then detect any voltage generated by the speaker
s voice coils and compensate for it, makeing for a very high
damping factor.
Velodyne powered sub woofers had a similar idea only they
used a velocity transducer fastened to the back of the speakers cone.
I have an old Urie catalog, I'll dig it up and see what else the
say about the sense lines.
If anyone wanted the info for a Urie amp I could scan the pages
and e-mail them to you.

Thanks
Mike Caldwell

[DL2246]

I have a pair of 6290 amps and currently use them to power four BassTech7 ServoDrive concert subs that weigh in at almost a half ton. They are a conservatively rated amp with a conventional power supply, four rack spaces and hefty at 60 pounds or so. The fan is a bit noisy but cools the heatsinks very well. With a slew rate of 50 volts per microsecond it's an exceptional value on the used market, going for $200 to $350 bucks. Only Chevin and Lab Gruppen can match that spec and those amps are like a bazillion bucks. The 6290's are a true 600 watts per side with a 4 ohm load and sound great. With a conventional PS they retain enough reserve power and won't crap out if the AC line voltage gets a little weird. They are big and heavy but if you have the rack space probably the best deal in old power amps.

[subwoof]

Did you realize that this thread is SIX YEARS OLD????

[JBL Dog]

They are big and heavy but if you have the rack space probably the best deal in old power amps.

Yup. I have three 6200 series amps. No doubt one of the best values out there.

:applaud:

[jbl_daddy]

I had a pair of 6290's a while ago, 10+ years ago, great amps very punchy. The fans were anoying and they sucked a lot of power when turned on. I had a line just for them in my electrical pannel. When turned on all at once from a remote pannel they will trip breakers in your house.:)

[speakerdave]

I have a pair of 6290 amps and currently use them to power four BassTech7 ServoDrive concert subs that weigh in at almost a half ton. They are a conservatively rated amp with a conventional power supply, four rack spaces and hefty at 60 pounds or so. The fan is a bit noisy but cools the heatsinks very well. With a slew rate of 50 volts per microsecond it's an exceptional value on the used market, going for $200 to $350 bucks. Only Chevin and Lab Gruppen can match that spec and those amps are like a bazillion bucks. The 6290's are a true 600 watts per side with a 4 ohm load and sound great. With a conventional PS they retain enough reserve power and won't crap out if the AC line voltage gets a little weird. They are big and heavy but if you have the rack space probably the best deal in old power amps.

I agree on all counts. A musical amp.

Though this thread is six years old, the amps are older and still providing good value for money, and they still show up on the used market, although I like to advise caution when buying used pro power amps on ebay.

[Mr. Widget]

I like to advise caution when buying used pro power amps on ebay.Over the past 6 years I have become significantly less open to the idea of buying vintage electronics. Of the basement full of older amps and other devices I have and have had like these older speakers we love, almost none of it actually works up to original specs.

As John pointed out on another thread... the amp may being "working", but sometimes it really isn't.


About a year ago people started complaining about the sound in one of the production studios here at the radio station. The studio has JBL 4412A speakers. I listened to the sound in the studio and something had changed!
There was a fuzziness to the sound, a low level distortion. The people said the speakers were bad, I doubted that it was the speakers. After checking out some things I figured out it was the old Crown DC300, I swapped it out with a different amp, sound was clean again.
I took the DC300 to the shop and hooked it up, put 8 ohm resistors on and put a 1khz sine wave in, hooked up a scope. What I saw on the scope just blew my mind! On the left channel the positive half of the sine wave was clipped about half way up, but the negative part of the sine wave was OK.
On the right channel the negative part of the sine was was clipped and the positive part was OK. This is very high amplitude distortion, but it didn't sound terrible, just kinda fuzzy. From what I saw on the scope I though it should have sounded much worse than it did! :biting:
For years I have know that speaker distortion is usually much higher than amp distortion. The reason that we love JBL is because of their low distortion. This experience has reinforced my conclusion that the quality of the speakers is far more important than the amp. I don't get hung up on amps. I use good amps but I don't go crazy over them, JBL speakers,YES!:D
I not putting down any one for their like or dislike of any brand of amp. John

Widget

[westend]

I use a 6290, driving low end in a biamped Altec set. More than enough power, of course. I have a replacement fan sitting on a shelf as the older stock fans are a bit loud. I'm thinking the newer fan will be much quieter.

JBL's own product literature states that the 62xx series are underrated as to the amount of actual power available. I've never tested mine but with that long row of Sanken's in there I don't doubt it has a lot of power to spare.

[Titanium Dome]

Well, well, here's a thread that's back from the dead.

This little discussion caused me to do a little research on the 6230 and 6260. They appear to be identical, spec-wise, to the Synthesis® S150 and S300 amps I got recently, which were made by UREI. :hmm: Facelift, anyone?

[hjames]

Well, well, here's a thread that's back from the dead.

This little discussion caused me to do a little research on the 6230 and 6260. They appear to be identical, spec-wise, to the Synthesis® S150 and S300 amps I got recently, which were made by UREI. :hmm: Facelift, anyone?

Well, I'm real happy with mine ...

[Mr. Widget]

This little discussion caused me to do a little research on the 6230 and 6260. They appear to be identical, spec-wise, to the Synthesis® S150 and S300 amps I got recently, which were made by UREI. :hmm: Facelift, anyone?Vintage gear and being up to spec aside, you might find this interesting...

Several years ago Zilch lent me a small 62XX that compared to the Hafler P3000. I compared them. Running them full range on my mini monitors, the Hafler P3000 was significantly better sounding. I suppose it also cost significantly more. Now that they are both dead lines the prices are likely more in line with each other.

Widget

[JBL 4645]

The famous Empire Leicester Square, screen #1 at London's West End, used them for its original, JBL 13KW THX sound system during the late 1980’s though to late 1990’s. The amps where removed and replaced with QSC and Martin Audio loudspeakers during 2000. About 5 years later it was all-revamped back to JBL and Crown power amplifiers and killer 56KW THX certification. :applaud:

http://forum.ecoustics.com/bbs/messages/47069/275681.jpg

http://forum.ecoustics.com/bbs/messages/47069/275682.jpg
More over at this thread: The Empire Leicester Square London a JBL installation!
http://www.audioheritage.org/vbulletin/showthread.php?t=13057 (http://www.audioheritage.org/vbulletin/showthread.php?t=13057)

[Russellc]

I agree on all counts. A musical amp.

Though this thread is six years old, the amps are older and still providing good value for money, and they still show up on the used market, although I like to advise caution when buying used pro power amps on ebay.
Unless something is really burned up, they are quite "fixable". subwoof walked me through the repairs to my 6230 ebay amp, and as dumb as I am, it is and has been working fine. Basically there needs to be a lot of solder reflowing, and replacement of a few small electrolitics. Then its good for another 20+ years.

Thanks again subwoof!

Russellc

[Russellc]

I use a 6290, driving low end in a biamped Altec set. More than enough power, of course. I have a replacement fan sitting on a shelf as the older stock fans are a bit loud. I'm thinking the newer fan will be much quieter.

JBL's own product literature states that the 62xx series are underrated as to the amount of actual power available. I've never tested mine but with that long row of Sanken's in there I don't doubt it has a lot of power to spare.
You might ask subwoof about this, he once told me that the fan could be quited down considerable if need be. Lower the voltage to it maybe? I didnt inquire B/C I dont have the 6290.

Russellc

[subwoof]

2 things would help the 6290 fan situation.

First thing is that the amp was designed to be stacked and racked and left on for a bazillion hours SO airflow through it's chassis was designed not to interfere with other rack components ( at least too much ).

If you removed the top and bottom covers, and cut out ALL the metal over *and under* the heatsink fins, and gave this a rack space above and below it would run a lot cooler and the need for high speed might never present itself.

If it did it would be the LEAST noticeable volume in that room...:)

Second is the value of the low speed resistor. The fan is a standard 120V bearing type and it needs to see 120V at start up then drop to the low speed otherwise it won't engage ( esp if worn ).

The stock value can be increased to make the fan spin slower OR not unless the "magic" temp is obtained ( rewiring required ) for home use.

I have 9 of them here from an install and later this month will be doing my analysis on this issue and will post a DIY thread.

There is also the issue of bias voltage but that is a little more advanced BUT easily checked / adjusted. This amp series tends to drift up with age and that WILL cause heat buildup and early fan engaging.

sub

[Fred Sanford]

I remember also a small resistor that you said was a chronic problem in these amps, and should be upgraded...do you have detail on that?

Thanks,

je (6260)

[John]

I thought the 6290 fan was always on???:hmm:

[subwoof]

Look at the schematic and you will see a thermal switch wired across the dropping resistor. When the switch closes the resistor is shorted and the fan gets full voltage.

If you actually REMOVED the resistor the fan would stay off until that temp is achieved, then go full speed.

If you simply put the thermal switch in SERIES with the resistor ( and fan ) then the fan would go to low speed only when the temp is achieved...

secrets out.

:cheers:

http://www.jblproservice.com/pdf/Vintage%20JBL-UREI%20Electronics/JBL-6290%20manual.pdf

[Russellc]

2 things would help the 6290 fan situation.

First thing is that the amp was designed to be stacked and racked and left on for a bazillion hours SO airflow through it's chassis was designed not to interfere with other rack components ( at least too much ).

If you removed the top and bottom covers, and cut out ALL the metal over *and under* the heatsink fins, and gave this a rack space above and below it would run a lot cooler and the need for high speed might never present itself.

If it did it would be the LEAST noticeable volume in that room...:)

Second is the value of the low speed resistor. The fan is a standard 120V bearing type and it needs to see 120V at start up then drop to the low speed otherwise it won't engage ( esp if worn ).

The stock value can be increased to make the fan spin slower OR not unless the "magic" temp is obtained ( rewiring required ) for home use.

I have 9 of them here from an install and later this month will be doing my analysis on this issue and will post a DIY thread.

There is also the issue of bias voltage but that is a little more advanced BUT easily checked / adjusted. This amp series tends to drift up with age and that WILL cause heat buildup and early fan engaging.

sub
Does the bias voltage drift on the 6230 as well? If so. I'd like to know how to measure and adjust it if possible. Thanks in advance,

Russellc

[subwoof]

Nearly all AB output amplifiers drift with age. Some up, some down. Look at the schematic and you will see a trim pot for each channel on the output stage on ALL of the urei/jbl amps.

Connect a voltmeter ( set to 2VDC ) across any output transistor's base to emitter junction for that channel.

What you should see after the amp has been powered up ( no load / signal ) for 10 min or so is the actual bias voltage.

If it is below .200 volts the amp will have a VERY SLIGHT crossover distortion. If it goes over .500 you will have a new toaster as the output stage will go into thermal runaway..

The goal here is to give it enough bias ( like the idle on a car ) to keep the distortion low ( not stall ) while not allowing excessive heat to build up ( radiator fan on ) and cause problems.

I usually aim for .250 to .300

NOTE 1: This is a general adjustment for bipolar output stages ( no matter WHO makes it ) and is not a substitute for the manufacturers recommendation.

NOTE 2: Some "fancy" makes and models, to get that magical itty bitty low distortion level, will recommend a "high" bias. This is not a very good idea unless you are sure that it can be tolerated...heat is heat and the laws of physics cannot be changed no matter how good a companies marketing dept can write.

The difference in distortion between .01 and .001 is about the level of a mouse fart in the closet down the hall when you are at "11"


If the amp is used for sub only use, the crossover distortion is inaudible so it can be tweaked much lower however the circuit can only go down to a fixed point.

sub