Carl,
Just in case you don't know it those UREI amps are very sought after by collectors and old analog studio guys. If you ever sell them you should get some real money for them. I sold an old UREI variable crossover to someone I know with a very high end studio here in Hollywood and he paid me more than it cost new.
Just in case you don't know it those UREI amps are very sought after by collectors and old analog studio guys. If you ever sell them you should get some real money for them. I sold an old UREI variable crossover to someone I know with a very high end studio here in Hollywood and he paid me more than it cost new.
Yea, I know some of those guys. It is surprising how good these amps sound once you consider how simple of a circuit is inside.
that is an interesting point ...
...
PS - all the "survivors" - (30 year amps) I see are VFA.
OS
That is a incomplete schema ... but , I can "see" the rest !
It looks like my next endeavor .. A cfa (yes , the UREI is one)
with the CF stage driven by an OP-amp
.a guess , but the dual diode input to the level shifters almost
assures this.
OS
You are right.That is a incomplete schema ... but , I can "see" the rest !
It looks like my next endeavor .. A cfa (yes , the UREI is one)
with the CF stage driven by an OP-amp
a guess , but the dual diode input to the level shifters almost
assures this.
OS
I couldn't fit the whole thing.
It has IC chips in front.
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Thank you ... ( could you make that more detailed).
(below ) is my work ...
PS - only down to 80ppm
. (just testing the waters) ...OS
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Must have been tired...
Well gents, I can attest to the fact these boards can withstand some rework.
I'm surprised no one noticed in looking at the pics I had previously put up that I somehow managed to install all the outputs the wrong way (incorrect polarity)! Had to remove all ten devices and switch them around. The bulb limiter earned its keep tonight.
After fixing that little mistake the OPS biased up and held a pretty steady idle current. The capacitance multiplier drops about 2V when being fed from my test supply of +/-32V. Given my lowish test supply I used 6.2kΩ resistors to set up about a 4.6mA current to simulate a front end being present.
Now on to a front end, some proper heat sinks and a proper PSU.
Well gents, I can attest to the fact these boards can withstand some rework
.I'm surprised no one noticed in looking at the pics I had previously put up that I somehow managed to install all the outputs the wrong way (incorrect polarity)! Had to remove all ten devices and switch them around. The bulb limiter earned its keep tonight.
After fixing that little mistake the OPS biased up and held a pretty steady idle current. The capacitance multiplier drops about 2V when being fed from my test supply of +/-32V. Given my lowish test supply I used 6.2kΩ resistors to set up about a 4.6mA current to simulate a front end being present.
Now on to a front end, some proper heat sinks and a proper PSU.
Well gents, I can attest to the fact these boards can withstand some rework
I'm surprised no one noticed in looking at the pics I had previously put up that I somehow managed to install all the outputs the wrong way (incorrect polarity)! Had to remove all ten devices and switch them around. The bulb limiter earned its keep tonight.
After fixing that little mistake the OPS biased up and held a pretty steady idle current. The capacitance multiplier drops about 2V when being fed from my test supply of +/-32V. Given my lowish test supply I used 6.2kΩ resistors to set up about a 4.6mA current to simulate a front end being present.
Now on to a front end, some proper heat sinks and a proper PSU.
Bulbs are cool , aren't they ! I usually just do the "thimios thing" and
just mount 1 pair OP.
I decided what my plan is. just 3 pair on the op boards (I received them-nice!!!)
With just a 2.1 system ... 1 "badger" for the sub , the pair of "slew's" for
my stereo pair.
PS - If I post my work ... it will be perfect (anal , of course).
JK - cool how you can "fake" an IPS on the OPS ... ehhh!
OS
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Bulbs are cool , aren't they ! I usually just do the "thimios thing" and
just mount 1 pair OP.
I decided what my plan is. just 3 pair on the op boards (I received them-nice!!!)
With just a 2.1 system ... 1 "badger" for the sub , the pair of "slew's" for
my stereo pair.
PS - If I post my work ... it will be perfect (anal , of course).
OS
Yeah, I think I'll likely do the same as Thimios too next time, instead of getting cocky and putting them all on at once.
Glad you like the boards. Are you going to space out the outputs by installing every other one or populate them all closest to the VBE? Oh, and please do post your work. I love to see how others implement their builds.
It looks like my next endeavor .. A cfa (yes , the UREI is one) with the CF stage driven by an OP-amp "
Yes, please! I'd like to see that.
Curiosity got the best of me. Here is a larger PDF of the UREI 6250. If you Google 'UREI 6250 User Manual' the PDF that includes this will be listed.
It's a VFA ! Lead comp + dc blocker are relegated to the IC. The quality
of the full amp will be determined by the topology of the IC.
As a reference the TL072 is a "blameless" with fet inputs , the NE5532
is a symasym ... etc...
Thanks ..... it is done (I will get it .. now)
OS
Best to DL the manual.
http://www.google.com/url?sa=t&rct=...62gDRHEiC0aEChXSObWPZXg&bvm=bv.63934634,d.aWc
it has the schematics in it.
http://www.google.com/url?sa=t&rct=...62gDRHEiC0aEChXSObWPZXg&bvm=bv.63934634,d.aWc
it has the schematics in it.
I'm not "ditching" the CFA.
I will succeed in making the diamond CFA better than the "VSSA".
On the VFA side , the spook and the symasui will be refined to
audiophile quality. This MUST be ... no more "childs play".
DIY must be brought to a proper compromise. (no more toys -projects)
Builds that your grandchildren will recap.
OS
I will succeed in making the diamond CFA better than the "VSSA".
On the VFA side , the spook and the symasui will be refined to
audiophile quality. This MUST be ... no more "childs play".
DIY must be brought to a proper compromise. (no more toys -projects)
Builds that your grandchildren will recap.
OS
My 8" 2-way daytons are 150 watts , my tang band 664(sub) is also 150w
.. all 3 amps must be close (150W) , on the slews .. I will space the pairs
for a better thermal "spread".
500W 2.1 system - pmpo would be massive !OS