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Post subject: Re: Question Re: bump sensitivity new spring reverbs Vs Old
Posted: Sat Oct 24, 2015 8:35 pm
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Found this original Gibbs-Hammond reverb tank on Ebay, should get it in a few days, it has the same code as some in vintage Fender reverb units I have seen in photos.Anyone have a vintage unit with one of these that can verify? seller says it works fine and is from an organ, and should work in guitar amps. I believe the code dates it at 1963, will get it in a few days.Image


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Post subject: Re: Question Re: bump sensitivity new spring reverbs Vs Old
Posted: Sun Oct 25, 2015 8:53 am
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my56strat wrote:
Found this original Gibbs-Hammond reverb tank on Ebay, should get it in a few days, it has the same code as some in vintage Fender reverb units I have seen in photos.Anyone have a vintage unit with one of these that can verify? seller says it works fine and is from an organ, and should work in guitar amps. I believe the code dates it at 1963, will get it in a few days.Image


Just be aware reverb tanks have an impedance. I'm not sure how this translates to performance, probably Arjay knows. I never really experimented with them. Tanks come in all sorts of configurations like length, decay time and impedance's.

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Post subject: Re: Question Re: bump sensitivity new spring reverbs Vs Old
Posted: Sun Oct 25, 2015 9:01 am
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The reason I went ahead and bought this tank is I've seen pics of original 60's Fender units with tanks stamped exactly the same, but these black stamps are the only markings on these old Gibbs Hammond tanks, it also has the stamp K inside near the springs. Arjay can you help on this?


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Post subject: Re: Question Re: bump sensitivity new spring reverbs Vs Old
Posted: Sun Oct 25, 2015 9:56 am
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I am not that familiar with the specifics of the 6G15 tank, having only owned one briefly in the late '60s and never having the need to service or repair it. That said, I can say that the alpha-numerics that comprise the tank's nomenclature are used to designate a number of parameters -- namely the length of dwell, the input and output impedances, the type of grounding scheme, and the method of mounting (flat, horizontal, vertical, etc).

You may find some additional data here......

http://wiki.surfguitar101.com/ReverbFaq

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Post subject: Re: Question Re: bump sensitivity new spring reverbs Vs Old
Posted: Sun Oct 25, 2015 11:29 am
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Thanks Arjay, there is some good info on that site, I have been searching for info on the old Gibbs Hammond tanks, and there is no info I can find on these codes stamped on front, the A0-23580-10, and the 1122-6341(the last four numbers are the date)is what I've seen on some early original Fender reverb unit tanks, so I took the chance to buy this one. The USA Accutronic tanks are easy to decipher, the one I need would be a 4AB3C1C, problem is I can't find one.


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Post subject: Re: Question Re: bump sensitivity new spring reverbs Vs Old
Posted: Sun Oct 25, 2015 12:18 pm
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The "1122" portion of the stamp *may* be a customer ID number. Jensen (and others) used this scheme when producing OEM components for a specific company.

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Post subject: Re: Question Re: bump sensitivity new spring reverbs Vs Old
Posted: Mon Oct 26, 2015 7:47 am
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"1122" is Gibbs-Hammond manufacturing EIA code.

To estimate the impedance of a 1kHz sine wave signal, you can measure the DC resistance across the coils. Then, use this chart to approximate the AC impedance (at 1kHz):

Image


Last edited by BMW2002Ti on Mon Oct 26, 2015 7:59 am, edited 1 time in total.

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Post subject: Re: Question Re: bump sensitivity new spring reverbs Vs Old
Posted: Mon Oct 26, 2015 7:53 am
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BMW2002Ti wrote:
"1122" is Gibbs-Hammond manufacturing EIA code.

From another EBay post:


Vintage Hammond-Gibbs reverb tank from 1960's. Model: AO-23580-10; 1122-6520.

Input impedance is: 1.3 ohms.

Output impedance is: 173.9 ohms.


That would seem to make sense. IIRC, the tanks intended for Fender's reverb-equipped combo amps measured 0.81Ω at the input and 81Ω at the output.

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Post subject: Re: Question Re: bump sensitivity new spring reverbs Vs Old
Posted: Mon Oct 26, 2015 8:02 am
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Sorry, Arjay... I found this chart after you posted your reply. The tank with those impedance number was a

Hammond-Gibbs Reverb tank AO 23580-15; 1122-6520. Not the 23580-10.

http://www.ebay.ca/itm/Vintage-1965-Ham ... 1877609223


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Post subject: Re: Question Re: bump sensitivity new spring reverbs Vs Old
Posted: Mon Oct 26, 2015 8:22 am
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I thought that might be the case. All of the OEM G-H tanks that I have photos of which are original to blackface combo amps have the metalized foil decal on the inside of the housing and the "1122" EIA code is stamped/engraved on the exterior. None have the P/N marked anywhere though the date code is often formatted as "AO-XXXX".

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Post subject: Re: Question Re: bump sensitivity new spring reverbs Vs Old
Posted: Mon Oct 26, 2015 8:42 am
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Ok, you guys lost me a bit, the one I bought in the earlier pic is what I've been seeing in pics of original units marked A0-23580-10, then 1122-6314(last four digits, year and week), so it will work? or no? here is one of the pics I've seen of an original withe the same tank I just bought.Image


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Post subject: Re: Question Re: bump sensitivity new spring reverbs Vs Old
Posted: Mon Oct 26, 2015 8:49 am
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Try it and see how it sounds. I don't think you'll do any damage to the unit, if the impedances are off, a bit. Just won't sound that good.


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Post subject: Re: Question Re: bump sensitivity new spring reverbs Vs Old
Posted: Mon Oct 26, 2015 9:11 am
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BMW2002Ti wrote:
Try it and see how it sounds. I don't think you'll do any damage to the unit, if the impedances are off, a bit. Just won't sound that good.


+1 although I think it'll work just fine.

Arjay

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Post subject: Re: Question Re: bump sensitivity new spring reverbs Vs Old
Posted: Mon Oct 26, 2015 9:15 am
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Thanks guys, as always I get the info I need here, and that was my next question, I didn't want to damage my reverb unit, would it be ok to test it outside the unit? meaning not bolting it in, just running the rca leads out to the new tank to test.


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Post subject: Re: Question Re: bump sensitivity new spring reverbs Vs Old
Posted: Mon Oct 26, 2015 9:19 am
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Absolutely.

The tank need not be installed in the cabinet to perform some simple bench testing.

Arjay

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