Coax Cable

[jborders5]

Sorry for another shielded cable post, but I'm struggling to find a definitive answer looking through all of the search results. Have the specs and/or source of the white coax used in the later amps been determined? Some posts say it has a low capacitance and some say it's higher. In the past I've used Belden 89259 (Teflon, 22AWG, 17pF/FT), but it's not very flexible and has a fairly large OD. The 89259 has a cult following as analog "audiophile" interconnects and is a great cable, but I'd like to find something easier to work with on a couple of builds I hope to start next month. Thanks.

[UltraHookedOnPhonix]

Sorry for another shielded cable post, but I'm struggling to find a definitive answer looking through all of the search results. Have the specs and/or source of the white coax used in the later amps been determined? Some posts say it has a low capacitance and some say it's higher. In the past I've used Belden 89259 (Teflon, 22AWG, 17pF/FT), but it's not very flexible and has a fairly large OD. The 89259 has a cult following as an analog "audiophile" interconnects and is a great cable, but I'd like to find something easier to work with on a couple of builds I hope to start next month. Thanks.

I could be wrong but the only Belden cable I could find in their catalog that seems to get close to the white coax seen in Dumble amps is Belden 83284. It's 50 Ohm coax with a 26AWG stranded (7x34) center conductor, 29pF/Ft and sports a white Teflon jacket.

[David Root]

FWIW two of the pro builders that frequent this forum use coax that appears very similar. Both appear to have 22 ga stranded silverplated conductors, one has noticeably thicker dielectric, of a different material than the other, both have silverplated braided copper shield and very similar offwhite outer sheath with a similar texturing on them. They both look like US milspec stuff to me.

I will measure their capacitances and come back on that, but looking at them I believe they are both less than 25 pF/ft.

UPDATE: Well I'll be a monkey's uncle! The one with the thinner dielectric is 31 pF/ft, the thicker dielectric is 26 pF/ft. (Assuming I measured it right).

[Max]

The one with the thinner dielectric is 31 pF/ft, the thicker dielectric is 26 pF/ft. (Assuming I measured it right).

Hi David,

these capacitance values are much lower then those of the white teflon coax cables I did see in some of the original Dumble ODS amps (70pF/ft and even higher).

Cheers,

Max

[guitarjazz]

I saw a coax cable that came with a Dumblator that was stiff as can be. I'll see if I can find out if their are any marking on it.

[guitarjazz]

I saw a coax cable that came with a Dumblator that was stiff as can be. I'll see if I can find out if their are any marking on it.

No markings whatsoever.

[glasman]

Here are my choices

RG188A/U Fused TFE Tape .110" 27.5 50±2 (7x .0067 strands) - Normally white
RG316 Ext FEP .102" 29.0 50±2 (7x .0067 strands) - Normally gold jacket
RG400 Ext FEP .195" 29.3 50±2 (19/.0080 strands) - Normally gold jacket. Very good for external patch cables.

Gary

FWIW, I also have some slightly larger diameter cable (about .15") that is Fused tape with a center conductor that is 22ga. Capacitance is measured at 17pf/ft. No markings at all on the cable. I bought it at the same store that Alexander used for years.

[guitarjazz]

OK here's a stupid Dumble question: did the big guy ever make an amp with a built-in Dumblator ? I remember reading that Lowell George's had built-in reverb.

[boldaslove6789]

Serial # 20 has a built in d-lator

[TheHandsomeOrk]

Are you sure that wasn't that an after market mod?

[glasman]

It that is the same ODS that I saw pictures of, the d-lator looked pretty Howie to me.

Gary