5235 Mod

[jblbgw_man]

I don't know if anyone has ever tried upgrading the 5532's in this crossover but I decided I would upgrade to OPA627 on a BrownDog adaptor pcb to see what all the fuss was about. Well the improvement was outstanding, clearer bottom end, much much cleaner mids and a more lively top end yet an overall smoother sound but still dynamic as all hell on my 4435's, for those of you still using this xover I can highly recommend this mod. I purchased mine from this ebay store http://stores.ebay.com.au/Parts-and-Audio but you can also get them direct from BrownDog http://cimarrontechnology.com/index.asp no affilliation. I haven't replaced the TLO74's yet as I understand they are still quite reasonable performers even by todays standards. But I will now go through my amps and bits and pieces to replace whatever they have used on the front end with these little gems, truley worth the effort IMHO. I have used 5532's for years but did'nt realise how ordinary they are. .

[Guido]

Yeah those BB opamps are great units.

I built a DIY active crossover based on BB 4134 opamps (instead of TL074) and the result was AMAZING.

[jblbgw_man]

I built a DIY active crossover based on BB 4134 opamps (instead of TL074) and the result was AMAZING.

Thanks for that Guido, I was wondering what was a good replacement for the TLO74's without having to go to the larger 4 IC Brown Dog adaptor pcb, I would be interested, have you actually done an A/B listening test between the TL074 and the BB 4134 ?

Does anybody have a schematic for the front end of a JBL MPX300 power amp ?

[scorpio]

I don't know if anyone has ever tried upgrading the 5532's in this crossover but I decided I would upgrade to OPA627 on a BrownDog adaptor pcb to see what all the fuss was about. Well the improvement was outstanding...

Thanks for the info, would you be able to ellaborate a little on the replacement process, is this easy to do by someone who bsically can solder small components, but has no real electronics knowledge? If this change is so good, I'd like to do it on my XO, but I am wondering if I could tackel the job myself or be better off asking a specialist to do it for me,

Thanks and sorry if this is a very basic question, it's another opportunity to learn something from this site!

Thanks,

[Guido]

I would be interested, have you actually done an A/B listening test between the TL074 and the BB 4134 ?

No A/B Test necessary. Listen to TL074, replace them and then listen to the BB's.
The 074 sounds lame and boring. Really.
Be aware that in my case listening is done via high end equipment. I have Passlabs amps and preamps!!

[Ian Mackenzie]

There are other chips around that are better and less expensive..

The best opamps are discrete opamps biased into class A as used in the Bryston and Pass labs crossovers

The BB are okay

Check out the LM4562 Buy it from digikey

[jblbgw_man]

Thanks for the info, would you be able to ellaborate a little on the replacement process, is this easy to do by someone who bsically can solder small components, but has no real electronics knowledge? If this change is so good, I'd like to do it on my XO, but I am wondering if I could tackel the job myself or be better off asking a specialist to do it for me,

Scorpio .. it is pretty basic as there are no SMD's (Surface Mount Devices) involved. Just unsolder the 5532'S with something like solderwick, being careful not to apply too much heat as to lift or damage the pads, the adaptors that I used in this instance have sockets for the DIP packages so the OPA's are "plug in" then it is just a matter of soldering in the new package, IMO only basic soldering experience is required.

Guido . I am currently in the process of tracking down the 4134 but can only find them in SOIC package so I will need a 14 pin SOIC to DIP adaptor pcb, BrownDog have these as well so I will go down this path.

Ian .. yes I was aware of the Bryston discrete opamp but was unaware of where to source them, I was going to use them on the front end of my BGW's to balance them some time ago, at the time I could'nt be bothered copying them myself and had instead copied the front end of the JBL ASC24 crossover which used OPA something a rather and instead of using discrete resistors it used a resistor matrix in the one SIL substrate package laser trimmed to 1%, I liked this idea as the topology was simpler but more importantly I also I liked the idea of the resistors being on the one substrate for temperature tracking, as you know any mismatch here results in wildly varing CMRR so I thought who ever designed the front end of this knew their stuff. I went to all the trouble of designing a pcb for this but never actualy implemented them . Is someone else coppying the Bryston discrete opamp? ... thanks for the heads up on the LM4562, I will look into it.

The problem guys in replacing the original opamps I am finding is that sometimes there is just not enough vacant realestate on the equipment pcb to accomodate the larger upgrade as generally one package is replaced by two packages plus the adaptor pcb .......... however as the results are so impressive it is well worth the effort and to nut out a soloution, luckily the 5235 has enough room to accomodate all the chips being replaced. Now to rip open my MPX300 for the HF section and replace the nasty 5532's on the front end of that and rip open my Australian Monitor 1k2 for the LF section and replace the 5532's in the front end of that....... then maybe the BGW's next and my Aphex gear after that Oh and one last thing ... please don't contact the ebay seller until I have purchased all that I need he has them at the best price ... he must have got a load in as samples or something.

:dont-know Now having said all that ...... I have used Aphex 124A's (-10dB to +4dB level interfaces) for some time and they use 5532's acording to the schematic and as far as I am concerned they are transparent in their sound .... so go figure, maybe and I say maybe that it is not the 5532'S chip that is at fault but more so the way it is implemented in the circuit, or the topology around it that effects it's performance, if you look at Aphex's topology around the 5532 it is vastly different to the way that others implement it, most topologies I have seen around the 5532 is nothing more than a kid with basic electronics and opamp knowledge would design (as in the JBL 5235). Anyway for this instance all I am interested in is sound improvment and the OPA 627'S are the way to fly and I might look into this 5532 topology a bit further when time permits.

Glad to share my experiencesand hope you all benift from the upgrade and knowledge.

[scorpio]

I have finally started to tackle this one and got 2 pairs of BB OPA 627 and a pair of brown dog adapters, but still have two practical questions before I do something stupid...

- the adaptors I have do not have the DIP sockets, is it OK to solder the OPA directly to the adaptors, or is there a danger with that?

- alignment of the OPA's on the adaptors, my 627 do not have the little half circle indent on one of the extremities that would match the print out on the adaptor, but instead have a little round mark at one end, I guess then that this little mark is supposed to align with the print out? Sorry if this sounds like double dutch, but I don't have the macro lense that would be needed to make a picture of this....

Thanks if you can make sense out of this and provide an answer!

[jblbgw_man]

I have finally started to tackle this one and got 2 pairs of BB OPA 627 and a pair of brown dog adapters, but still have two practical questions before I do something stupid...

- the adaptors I have do not have the DIP sockets, is it OK to solder the OPA directly to the adaptors, or is there a danger with that?

- alignment of the OPA's on the adaptors, my 627 do not have the little half circle indent on one of the extremities that would match the print out on the adaptor, but instead have a little round mark at one end, I guess then that this little mark is supposed to align with the print out? Sorry if this sounds like double dutch, but I don't have the macro lense that would be needed to make a picture of this....

The only danger of soldering the OPA's directly to the adaptor pcb is 1) if you apply too much heat from the soldering iron causing the tracks to lift or damage and 2) if you apply too much solder and bridge the tracks ...... be careful.

Re alignment ....It's unusual for the OPA's not to have an indent marking but anyway don't loose any sleep over it, if it has a tiny 1mm round circle/hole adjacent to one of the end pins this usually designates pin 1 OR look at the writing on the OPA's so that it's the right way up, then the bottom left hand pin is pin 1, although this could be slightly risky if they have stamped them upside down

When soldering them onto the adaptor pcb (knowing where pin 1 is on the adaptor pcb) install the OPA's so that their pin 7 is electrically connected to pin 8 on the adaptor pcb and then to check you should find that the OPA's pin 4 is electrically connected to the adaptor pcb's pin 4

Good luck

[jblbgw_man]

Just further to this post I am now considering re designing the 5235 using DC coupled discrete op amps and having a matrix of sorts that will duplicate either 12 or 18 dB filter slope layouts instead of using plug in cards. I would also make the new pcb the same size so it's just a matter of removing the 5235 pcb and installing this new one ....... all because I want to keep to the original 4430/4435 voltage drives and phase response.

[scorpio]

OK, I've done the mods today, soldering was easy, desoldering the 5532 was more of a pain, I'd bought solder wick for that job, but it did not work very well.

Anyway, maybe I would not go as far as but I would certainly rate this as (it's all relative). Certainly for the cost and the work it is 100% worth it, much improved clarity, transparency and definition, and in my opinion improved dynamic and slam.

Now next question, should any of the condensers be upgraded as well???

[jblbgw_man]

Now next question, should any of the condensers be upgraded as well???

Yes yes yes ... audio grade electrolytics is what I used, I did the whole thing together, BB chips and caps at the same time, so I can't comment on the cap only improvment but it should be worthwhile ..... glad you are happy with the improvment so far .... what monitors are you using? Did you also replace the TL074's?

[scorpio]

No I've not changed the TL074 (yet?), I will be looking into that at the same time as the caps to order everything in one go. What is the time limiting factor in this is having the time to remove the filter from the overall system as I'm using the strip connectors, not the XLR's, so I have to remove the cabling to the various amps, a royal pain.

I'm using a system based on 2235, 2450 and 2405, with a cc network between the 2450 and 2405 that is based on the 3106, it's the system you can see in my avatar.

I'm sticking to this crossover for now as I'd like to experiment with 2380 type horns at some time, and i have the necessary cards for doing so.

[Ian Mackenzie]

BB 4134

I build an active crossover using this chip about 10 years ago

That chip is actually quite coloured compared to say the OP 275

But any mass produced chip on a die is not going to perform as well as a discrete mininalist buffer. I found such chips lacked true resolving power and dynamics.

This is why most active crossovers degrade audiophile performance.

You might gain a bit of bass damping on systems like the 4344 but it otherwise downgrades the signal from the program source using hi end components

The thing is with most garden variety power amps this loss of quality introduced by an active crossover may not be particularly noticeable.

Its a case of using like with like quality

[jblbgw_man]

The thing is with most garden variety power amps this loss of quality introduced by an active crossover may not be particularly noticeable.

Its a case of using like with like quality

Ok I get it now ..... I should be using Radio Shack speakers with my gear .... now I know where I have gone wrong thanks for the tip.