Hammond reverb tank replacement.

[K.Hogg]

Hello ,
I'm trying to figure out the connector code for example - Grounded/Output Grounded etc for this Hammond 2 spring reverb tank so I can replace with a 3 spring, here's the link
- https://www.ebay.co.uk/itm/293130826...UAAOSwr~lYo1ic.


The amp is a Vox Rose Morris super twin solid state , with two 5 inch speakers. here's a link to the diagram- https://schematicheaven.net/voxamps/suprtwin.pdf
The diagram sates the part is a Hammond "6EC38" or it could be "6EC3B" looks more like an 8 to me.
Any advice would be greatly appreciated

[Chuck H]

Well that would appear to be an Accutronics tank. I think they were a division of Hammond when that amp was made. And I've never seen a tank like that. Though I think Belton makes a tiny 2 spring tank now.

I can't find any info on the Hammond part number on the schematic and I'm not qualified to fact check your impedance choices on for the tank you propose. Hopefully someone here that can will. If you're unsure you may want to hold off on purchase until that happens.

And, even if you have room for the bigger tank in that amp there may still be an issue with noise. Positioning a reverb tank for lowest noise is often necessary and will be impossible if you don't have much room.

[K.Hogg]

Hey Chuck , Thanks for your info. ok so I need to match input and output impedance along with the connector code ? I was assuming you didn't.
In regards to noise, I take it I should position the tank as far away from the power transformer as possible? would putting shielding foil under the tank Help with noise ? as the tank is open on the underside and not closed off.

[TomCarlos]

Like Chuck said, hard to find info on this tank. But I would ask, are you absolutely sure this is the original reverb tank? It looks like there is a base and the cover is either riveted on or is there something else that is holding it on?

[Chuck H]

Hey Chuck , Thanks for your info. ok so I need to match input and output impedance along with the connector code ? I was assuming you didn't.
In regards to noise, I take it I should position the tank as far away from the power transformer as possible? would putting shielding foil under the tank Help with noise ? as the tank is open on the underside and not closed off.

If the open end of the tank will be exposed to EMF from the amp electronics it would be a good idea to shield it. I can't know how it will be mounted. That said...

It's not always distance that gives quietest results because sometimes the necessary distance isn't possible. You have to scootch the tank around and sometimes even change orientation to find any place where EMR from transformers and such has the weakest influence on the reverb tank transducers tendency to induct and reproduce noise. Sometimes it's a VERY narrow margin. I've even had to mount reverb tanks in unusual orientations contrary to their design. Always with the intention of getting a tank for that orientation but never actually getting around to it Which is just as well I think. Because a new tank with a different design might require a yet different orientation. Seriously, making reverbs "work" as well as possible is a kind of black art due to all the circumstances involved and how they interact. There's no clear rule book for it.

[K.Hogg]

Hey Tom , Pretty sure its the original as Its the same as others I've seen in pictures of this amp. the tank is completely sealed.
here's a link of pics from another amp https://www.j-guitar.com/products/de...384489&lang=en

[TomCarlos]

Ok....

The link you posted is to a restricted site. So unless we're members, we cannot view the post/photos.

[K.Hogg]

Like Chuck said, hard to find info on this tank. But I would ask, are you absolutely sure this is the original reverb tank? It looks like there is a base and the cover is either riveted on or is there something else that is holding it on?

Hey Tom , Pretty sure its the original as Its the same as others I've seen in pictures of this amp. the tank is completely sealed.
here's a link of pics from another amp https://www.j-guitar.com/products/de...384489&lang=en

[TomCarlos]

One more lead....

I found a thread here on MEF - Marshall 2205 JMC800 Reverb does not work.

Look at post #7. It mentions the ACCUTRONICS, CARY. IL. Pat 2.982.819 Pat.3.106.610 8DB2C1D." I think your tank has the same patent number and ID number.

If that is the case, perhaps you have the equivalent of a ModŽ 8DB2C1D.

[K.Hogg]

If the open end of the tank will be exposed to EMF from the amp electronics it would be a good idea to shield it. I can't know how it will be mounted. That said...

It's not always distance that gives quietest results because sometimes the necessary distance isn't possible. You have to scootch the tank around and sometimes even change orientation to find any place where EMR from transformers and such has the weakest influence on the reverb tank transducers tendency to induct and reproduce noise. Sometimes it's a VERY narrow margin. I've even had to mount reverb tanks in unusual orientations contrary to their design. Always with the intention of getting a tank for that orientation but never actually getting around to it Which is just as well I think. Because a new tank with a different design might require a yet different orientation. Seriously, making reverbs "work" as well as possible is a kind of black art due to all the circumstances involved and how they interact. There's no clear rule book for it.

OK thanks. I'm now wondering if the original stock tank was the correct impendence as the reverb was very quiet and the reverb pot to be turned up max to get a decent sound - could they have just thrown anything in that worked?

[K.Hogg]

One more lead....

I found a thread here on MEF - Marshall 2205 JMC800 Reverb does not work.

Look at post #7. It mentions the ACCUTRONICS, CARY. IL. Pat 2.982.819 Pat.3.106.610 8DB2C1D." I think your tank has the same patent number and ID number.

If that is the case, perhaps you have the equivalent of a ModŽ 8DB2C1D.

Thanks tom , I've had a look on the web there and saw the exact same patent number on different tanks of the era so I don't think it can be used to identify my tank.

[Enzo]

6EC3B seems more like it to me. Yes the drawing is hard to tell, but 3B fits their number pattern while 38 doesn't. Note also it is an EC rather than EB, so the output end is higher impedance than usual. I don't get the schematic, it APPEARS that the reverb is like a single transducer somehow in series. But in your photo, which crops off half the unit, it APPEARS t have two sets of wires. So it appears to me it won't be as simple as just substituting a different pan. You will need to figure out how to wire two separate transducers into this circuit.

[Mick Bailey]

To me the schematic appears to conceptualise the tank and shows only the signal leads, ignoring the grounding scheme.

I would go back to basics and take some measurements off the existing tank just to be sure. Make a note of where the connections go, then unsolder and separate the ground (black) leads and using a DMM check the resistance of the input and output transducers (measure each between green and black). Also check whether either transducer is grounded the the tray. You can then cross-reference the DC resistance to the impedance here https://www.amplifiedparts.com/tech-...d-and-compared - scroll down to the table showing input and output impedance. Sometimes the output transducer can read excessively high (2k ohms or more DCR) which can account for a very weak reverb.

That's an interesting design - I wonder if it's a folded spring type, or a Z configuration (like some Cascade units) to give a longer effective spring length.

[K.Hogg]

To me the schematic appears to conceptualise the tank and shows only the signal leads, ignoring the grounding scheme.

I would go back to basics and take some measurements off the existing tank just to be sure. Make a note of where the connections go, then unsolder and separate the ground (black) leads and using a DMM check the resistance of the input and output transducers (measure each between green and black). Also check whether either transducer is grounded the the tray. You can then cross-reference the DC resistance to the impedance here https://www.amplifiedparts.com/tech-...d-and-compared - scroll down to the table showing input and output impedance. Sometimes the output transducer can read excessively high (2k ohms or more DCR) which can account for a very weak reverb.

That's an interesting design - I wonder if it's a folded spring type, or a Z configuration (like some Cascade units) to give a longer effective spring length.

Thanks guys !
Ok I've measured the resistance of the IN and OUT transformers. I was not getting any reading for the OUT on the 200 ohm setting so I changed to the 2K ohm setting.
the IN reading was - .056
the OUT reading was - .707

Mick - How do I check if the transducer is grounded to the tank as you suggested? the tank is a completely sealed unit.

On a side note guys I'm not able to attach any more pictures to this post I've only added one so far, its now giving me the message - IMG_4584.jpg
Upload failed. You have exceeded your usergroup's upload quota of 976.6 KB by 2.09 MB. any ideas lol ?

[The Dude]

Use software to compress your photos (Everyone should do this anyway). Photoshop works well. If you don't want to buy something, Gimp is a good freeware editor. Photoshop has a menu item called "save for web" that allows different levels of compression. I'd bet Gimp has something similar. Not only does uploading large full resolution photos waste valuable server room, it also makes web pages load slower.