Dont like the bb2134 in quad 34,replace them back?

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tony71

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Joined 2006
#1
Hello all,

I have a quad 34 preamp thats been to an ingenieur in Holland to replace the opamps.They have been replaced by the OPA134 or OPA2134.
I also have a quad 405-2 who had the opamps replaced by bb 134
When i got the set back i started listening.
It sounded terrible.The high tones were not nice to listen.
I changed the opamps in the 405 back to the tlo71 and also put in the ne 5534 and the sound was a lot better.With both of these opamps.
I think the bb 134 had oscillation...I am not an elektronic expert so i dont know for sure.
But i am not happy after all.The sound is still to sharp.My old marantz preamp (1976 ) sound better then the quad 34...
So now i want to change the opamps back in the quad 34.
Should i do that with the ne series 5534/32/33?
Or the new tl2071 series?
Or stick with the old tl071?
I have 8 tl071cp and 4 tl072cp they were in the quad 34 officially.
Can someone help me and tell me which opamps i have to get?
A replacement for the tl071 and a replacement for the 072cp?
 
#2
Nobody?

Then i just put the tl071 back in the preamp.
I dont like the high treble that comes out off the set.
Its no fun to listen to.
Is it possibel to place the ne 553xx series in the preamp?
Anyone here ever serviced a quad 405 or 34/44 preamp?

Regards,

Tony
 
#4
I don't want to offend you and I also don't know what your source and speakers are but, maybe it is now more precise and it reveals the flaws of the source.....If it is the case you can borrow a better source and try again with the OPA134.
Just trying to help....
 
#7
Okay , guys.

Thanks first for you reply`s.
Maybe it is that i am not used to the new opamps.
I am going to listen to some more recordings and decide then what i am going to do.
Everyone i am asking for the advice is very enthousiastic about the bb opamps so i ll give it a try.

Regards,

Tony
 
#9
Hello, Stuart.

Thx for your advice.
The ingenieur here in holland also changed the capacitors.
He replaced everything thats aged.
I have listened the 405-2 with another preamp.
A marantz.
Now i am sure.I am going to replace the opamps back in the 34.
I dont like the harsh sound at all.
Maybe its just my ears...

Regards,

Tony
 
#10
I have rebuilt a large number of 34s and 405s using OPA134s this was the comment from the last customer

Hi,
Fired up the amps this morning. They sound fantastic, they're not really warmed up yet either. Great clarity and weight without a hint of harshness. You were right, they work well with the quad speakers. Thanks again, good doing business with you,

Cheers,
Gordon

So I am surprised that you have problems with them. If you replace the opamp in the 405 with the original you may have to replace the capacitor between pins 1 & 8 as it is not required for the OPA134 but may be necessary with the TL071 or LM301 in the 405

Stuart
 
#11
Thx for thinking with me ....

A friend of mine is putting sockets in the quad 34 , so i can try and hear the difference.
I tell u my experiences when its finished.
Now i am playing the qiad 405-2 with a marantz 1060 as preamp.
It changed the opamps in the 405 to the ne5534.
This sound better.
I ve treid it again with the 34 but its no fun to listen to.

I lett you know how the progress went.

Regards,

Tony
 
#12
Tony

Did your "ingenieur " put C77 the correct way around or just replace it same as the original ??

The 34 was actually designed for an even earlier op-amp than TL071- one that would guarantee a +ve output at each op-amp by way of the asymmetric supplies and so the 100uF coupling caps would all be happy ;-)

If you want to "keep up with jones's" then try TLE2071 or OPA134 - NE55xx Do not work well in the 34 or 405 and you're probably "listening to" enough of them any way as so many recording desks will use them.

More @...

http://www.dc-daylight.ltd.uk/Valve-Audio-Interest/QUAD/QUAD-34-Modification/QUAD-34-Mods.html

Regards

Keith
 
#13
If you think you might be getting Oscillation from the OPA134/2134"s then you might try putting a 22pF ceramic cap between the Supply pins of the Opamp which might stop it from oscillateing......

Also the TL071/72/74 chips seem to like to see a Higher Input impedance than the 2134/134 chips so maybe lowering the Value of the Input resistors might also help.....


Good luck
 
#14
I know acording to the datasheet there is not much diffirence between the opa2134 and 2132, but I find in practice, in the experimental boards I built, the opa2132 is consistently better.

I have one realy nice dual mono opa134 headphone amp I build from chips donated by Franz G. My wife uses it daily... it REALY good for a little battery operated unit.

I'm at this very moment stuffing an opa2132 headphone PCB I made this afternoon...
 
#15
Funny the C77/C78 caps appear to be screen printed the correct way around in my Quad 34 - I followed the circuit traces manually using the circuit diagram as reference and everything led were it was supposed to. Perhaps this problem is only present on the earlier models? Mine is SN 7001.

As for op-amps my Quad 34 is singing away nicely with a mixture of OPA627s (bypassed with 0.1uF caps as per data sheet) and OPA227s. Seldom heard a pre-amp sound so clean and open before.

Cheers,

- J
 
#16
After a long time , i decided to sell the quad 34 and replace it with a mitsubishi diatone preamp.
Now the quad 405/2 is really singing.
I had a sphinx myth 1 preamp before that sounded even better on the 405 then the quad 34.
I guess the quad 34 is just not that good....


Regards,

Tony
 
#17
After upgrading mine I think it's a very neutral sounding pre-amp (when comparing it with a passive pre-amp with my Gainclone/Amp6 Basic and Greg Ball GB150D amps). It did take alot of effort to upgrade it though even down to using hand matched metal film resistors, but it made a huge difference in sound.

Still each to his/her own, and I'm glad you are now happy with the sound from your Quad 405/2 😀

- John
 
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