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Questions about spring reverb specs

Started by Electron Tornado, May 01, 2018, 03:27:02 PM

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Electron Tornado

I am repairing a Laney HCM30. Since the circuit board is the same as the version with reverb, I thought I would go ahead and add the reverb.  The service diagrams can be downloaded here: https://elektrotanya.com/laney_hcm30r_sch.pdf/download.html

The reverb tank shown in the Laney diagram is BB3E1B. It doesn't say whether it was a type 1 or type 8, however. I'm guessing it's a type 1. A google search of that tank gives zero results, and there seem to be no tanks with that same code available online.

Here are some questions:

1. The input and output impedances between a type 1 and type 8 with "BB" are:
Type 1   input 150 ohms, output 2250 ohms
Type 8   input 190 ohms, output 2575 ohms

How critical is it to match those impedances? Can a type 8 be used in place of a type 1?

2. From the Accutronics web site, in the digit for the connectors,  "E" means there is "No Outer Channel". (This is the same for both type 1 and 8.)  How critical is it to find a tank with that digit?

3. For the connectors digit, how critical is it whether the input and output is grounded or insulated? Can I substitute one of those for a tank with "No Outer Channel"?

Thank you.

galaxiex

#1
1.
The impedance is so close I don't think it would matter which one you use.

2. and 3.
The MOD reverb tanks have solder pads on the connector board that can be bridged with a solder blob, or not,
giving you the option to have both grounded, or none, or one or the other.

MOD reverb tanks at Amplified Parts are reasonably priced and good quality.
I've used a couple of them and have been happy with them.

https://www.amplifiedparts.com/products/reverb_tanks?filters=Brand%3DMOD

Also check Studio Sound Electronics for the "Revisit" brand.

http://www.amprepairparts.com/reverb.htm

These also have the solder pads for grounding options.
I have used these tanks as well and they are very nice.

If it ain't broke I'll fix it until it is.

g1

'no outer channel' is the cheapo version where the outer 'tank' is not used, and the inner 'pan' is mounted directly to the chassis on foam or something.  No connectors, just bare wires.  That's why you can't find them, you could try through a Laney dealer if you really want.

I'd suggest the 4BB3C1B as used in other Laney, and adjust the solder jumpers like galaxiex mentioned (mod brand) if required.

Enzo

No outer channel means the 1 series is just the innards without the whole "pan".  The 1 series is just the spring guts, you find them inside practice amps.  You could make a 1 from an 8 by pulling the pan from around the innards.

The reverb pans are for guitar amps.  NOTHING in a guitar amp is precise and critical.  You get remotely close and you are good to go.

If you have room for a whole pan, whether an 8 or a 4, use it. 

Electron Tornado

Thanks for the replies. The info was very helpful!