Longer speaker cables or interconnects

dill,

no moisture. Sorry.

Old? The speaker’s serial # puts them at 1954, the year I was born. 

Now that’s old!

Unreceivedogma, it appears that your preamp provides two RCA outputs. "Output 1," at least in stock form, has an EXTREMELY high output impedance of 100K, that was apparently suitable for use with a matching Beard power amp, but very definitely would not be suitable for driving long cables or a majority of other amps. "Output 2" has a specified output impedance of 600 ohms, although I wouldn't be surprised if that number rose to considerably higher values at deep bass frequencies.

Also, it appears that your sub has an external crossover/amplifier, with a fairly low input impedance of 20K. I don't know what the input impedance of your amps may be, but I suspect it is relatively high.

Before providing any suggestions, my questions at this point are:

1)How are you connecting the OTL amps and the sub's crossover/amplifier to the preamp? If one is connected to "Output 1" of the preamp and the other to "Output 2," which is connected to which?

2)By any chance do you know if the capacitor upgrade that was performed on the preamp included the output coupling capacitors?

3)And if so, do you know what the values of the new output coupling capacitors are, i.e., the number of uF (microFarads)?

4)If you know the input impedance of the amps, that would also be relevant information.

Also, a minor correction for the record, if I may: The musician you referred to is Al Kooper, not "Cooper." As you may be aware, also, prior to his BS&T days he was a member of the Blues Project, a great group IMO!

Regards,
-- Al

I went to The Cooper Union, I’m always making that mistake. Oops.

As for for the rest of your questions, they will have to wait until everything comes back out of their boxes.

That said, I have been running the Beard with the Futterman from either output with no discernible difference for 28 years. Specter returned the Beard to stock (except for the caps) two years ago, he did everything on the OTLs also and then tuned it all to the room.

The sub is a new addition to the system. I’ve used it only for a month or so before packing it up and haven’t really had a chance to fine tune things, but it sounded good though not great and made the Altec sound noticeably clearer. It went to output two.

all the caps were upgraded. Every one. 

OK. Given that, and pending any further info you might be able to provide after the equipment is unboxed, and given also that the 604c is specified as an 8 ohm driver, I suspect that with this particular equipment what would be best is:

-- Connect Output 1 to the amps via the shortest possible cable length. And preferably with cables having low capacitance, for example Blue Jeans LC-1 (12 pf/foot).

-- Connect Output 2 to the sub’s crossover/amplifier via whatever cable length is necessary. If the output impedance of Output 1 with the cap upgrade is anything remotely close to the original 100K spec it would not work well with the sub.

-- Connect the speakers to the amps via whatever cable length is necessary.

Generally speaking, low speaker impedance (which is not the case here) tends to increase the importance of minimizing speaker cable length. High output impedance of a component providing a line-level signal (which is certainly the case here) tends to increase the importance of minimizing interconnect length (although much less so in the case of a sub, for which cable effects on the treble region are unimportant). The use of unbalanced as opposed to balanced interconnections also tends to increase the importance of minimizing interconnect length.

Again generally speaking, my reading of the many previous threads in which the long speaker cable/short interconnect vs. short speaker cable/long interconnect subject has been discussed has been the same as yours, that "the preponderance of opinion is to put the amps near the speakers" (quoting from one of your earlier posts). However the specifics of your particular equipment appear to greatly overshadow any such generalities. Bill (Grannyring) had it right!


Good luck. Regards,
-- Al

Almarg,

stock 604B, C, and D were 16 ohms. They can be modified to 8. When I had them re-coned, I kept them at 16. Jon said the Futterman much prefer the 16.

E and up are at 8.

I will ask Jon about the output impedance of both taps. I’m sure he must have thought of it and never explained to me, figuring it’s tmi, but you never know.

Thanks for the advice. Looks like I have had it more or less right all along.