Differences is various B&K EX442s?

Crang

Well-Known Member
I just ended up winning an auction for some Dahlquist DQ-20s. These will be my main drivers while my ADS 1590s come down for a total rebuild. And who knows, I may fall in love with them and decide to mod the heck out of them.....so now I am in the market for an amp. Everything I have seen says the B&Ks warm sound matches nicely with the power hungry 20s.

I am looking specifically at the EX442. It seems like they made a few variations of it over the years. I think the older ones are the ones with gold trim and handles and the Sonata series is the newer one with no handles a some red/blue logo on the faceplate, but I could be wrong on this. The Sonatas are not near as pretty but I did spy some XLR inputs on one of them just looking at photos of auctions.

Can anyone tell me the differences between the Sonata series and the gold trimmed ones? Is either better or is there a preference? I really do not want a project amp so perhaps the a newer 442 would be better? The gold trimmed ones are more attractive by a wide margin, and balanced inputs arent important to me.
 
There seem to be more variations in the Sonata series (red/blue with black faceplate). Some had heatsinks in the rear with symetrical rca's, others with rca's to one side of the heatsinks, and still others had heatsinks within the chassis. I haven't been able to identify sound differences among the Sonata series. I have never owned the older, prettier amps.
 
The Sonata I had used 2SK332 JFETs and the input diff pairs instead of the normal bipolars. It was otherwise pretty much the same as the newer 4420s.
 
I had a Sonata model and I wish I could recall the details. I had some info I cannot now find and it seems ATI (who bought the B&K assets some years back) no longer has legacy product info their site.

All subject to correction... there were two earlier models with the gold handles and brand imprint. One was a dual transformer, the other had a larger single transformer. There were different circuit boards but don't know if the circuits were significantly changed.

The Sonata replaced the above and had a different layout in terms of circuits and with the connections on the rear in later production models. The earlier models had inputs beneath the heat sinks which was a pain. The Sonata model was rated the same power but had a higher spec for current delivery and damping factor. There were also changes in the number of output transistors or the type, or the power supply, I don't recall exactly, that allowed for higher current output.

The later model was designated EX4420 and had all heat sinks within the chassis. Different output components. The overall impression was a neater build which may not have resulted in different sound but must have been more efficient in terms of production.

I have only heard the Sonata model. The earlier model PERHAPS had a bit more cache in terms of better perceived sound. I enjoyed the sound compared to the Adcom 555ii I had at the same time. The Adcom actually had a better sense of bass control which surprised me but overall the B&K was preferred. I later bought an ATI 1502 which, while spec'd lower in power, was better in all ways. I later bought a second which worked out very well. I passed along the B&K without regret.

So, I can't relate the sound difference, if any, between the generations of the amp. I suspect the earlier model will work out fine since the Dahlquist was not a low impedance design, requiring more current delivery.

All said, these are old amps and subject to the effect of age. I had to do some circuit trace repair on my unit as some had loosened for some reason. These units do get warm both inside and out. Shop carefully.
 
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