[jtougas[_3_]]

Hi folks -

I picked one of these up a few years ago, and while I've always liked
the delay portion of it, the reverb always sounded a little weak. So,
acting on impulse, I pulled out the little 2 or 3 inch long reverb
tank, and riveted in a 9 inch Accutronics from a Carvin amp that had
recently gone up in smoke (not my fault, I never touched the insides
of it! - shame, too, great sounding amp).

So, now the reverb tails off much more nicely, and sounds better, only
it's much more dim than it was before.

So, what do I need to do to the circuit now? Replace some caps? Change
out a potentiometer? Both? Neither?

Look somewhere else? *grin*

Any leads would be appreciated.

Thanks -
--
jtougas

"listen- there's a hell of a good universe next door
let's go" - e.e. cummings

[Scott Dorsey]

jtougas wrote:
Hi folks -

I picked one of these up a few years ago, and while I've always liked
the delay portion of it, the reverb always sounded a little weak. So,
acting on impulse, I pulled out the little 2 or 3 inch long reverb
tank, and riveted in a 9 inch Accutronics from a Carvin amp that had
recently gone up in smoke (not my fault, I never touched the insides
of it! - shame, too, great sounding amp).

So, now the reverb tails off much more nicely, and sounds better, only
it's much more dim than it was before.

So, what do I need to do to the circuit now? Replace some caps? Change
out a potentiometer? Both? Neither?

Odds are that the reverb tank you installed has different impedances on
the coils than the one you took out.

Find out what the impedance of the coils are on the original, then call
up Accutronics and order a new one with the same values. Brand new
Accutronics units built to spec are only twenty bucks or so.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[jtougas[_3_]]

On 21 Jan 2008 21:49:16 -0500, (Scott Dorsey) wrote:

Find out what the impedance of the coils are on the original, then call
up Accutronics and order a new one with the same values. Brand new
Accutronics units built to spec are only twenty bucks or so.

Really?

Well, hell, that's not nearly as complicated as what I was thinking
of...

Thanks, Scott.

--
jtougas

"listen- there's a hell of a good universe next door
let's go" - e.e. cummings

[[email protected]]

On Monday, January 21, 2008 at 11:49:27 AM UTC-5, jtougas wrote:
Hi folks -

I picked one of these up a few years ago, and while I've always liked
the delay portion of it, the reverb always sounded a little weak. So,
acting on impulse, I pulled out the little 2 or 3 inch long reverb
tank, and riveted in a 9 inch Accutronics from a Carvin amp that had
recently gone up in smoke (not my fault, I never touched the insides
of it! - shame, too, great sounding amp).

So, now the reverb tails off much more nicely, and sounds better, only
it's much more dim than it was before.

So, what do I need to do to the circuit now? Replace some caps? Change
out a potentiometer? Both? Neither?

Look somewhere else? *grin*

Any leads would be appreciated.

Thanks -
--
jtougas

"listen- there's a hell of a good universe next door
let's go" - e.e. cummings

i realize this post is 7 years old but you said that you changed out the spring and i was wondering if you could tell me where the connections were on the PCB? Mine had the spring unit ripped right from the board with very little of the wires remaining. i took a guess and rewired it but it doesn't work so i guess i did it wrong.
thank you

[Scott Dorsey]

wrote:

i realize this post is 7 years old but you said that you changed out the sp=
ring and i was wondering if you could tell me where the connections were on=
the PCB? Mine had the spring unit ripped right from the board with very li=
ttle of the wires remaining. i took a guess and rewired it but it doesn't w=
ork so i guess i did it wrong.
thank you

The spring unit only has four wires... two going in, two coming out. If you
put a 2" speaker across the two going on, you should hear the speaker making
some sound. If you put it across the two coming out, when you tap the speaker
you should have sound in the output. So you can use this as a diagnostic to
make sure the electronics are good.

You can also check the resistance across the spring unit with an ohmmeter...
if the values are very high, odds are the spring unit was damaged in the
tearing-out process and should be replaced. Antique Electronics Supply
will carry replacement Accutronics spring delays but you will have to make
sure the impedances are correct since there are a lot of different options.
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[JackA]

On Thursday, July 9, 2015 at 8:47:58 AM UTC-4, Scott Dorsey wrote:
wrote:

i realize this post is 7 years old but you said that you changed out the sp=
ring and i was wondering if you could tell me where the connections were on=
the PCB? Mine had the spring unit ripped right from the board with very li=
ttle of the wires remaining. i took a guess and rewired it but it doesn't w=
ork so i guess i did it wrong.
thank you

The spring unit only has four wires... two going in, two coming out. If you
put a 2" speaker across the two going on, you should hear the speaker making
some sound. If you put it across the two coming out, when you tap the speaker
you should have sound in the output. So you can use this as a diagnostic to
make sure the electronics are good.

You can also check the resistance across the spring unit with an ohmmeter....
if the values are very high, odds are the spring unit was damaged in the
tearing-out process and should be replaced. Antique Electronics Supply
will carry replacement Accutronics spring delays but you will have to make
sure the impedances are correct since there are a lot of different options.
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."

OT:

Not sure why, but I was given (decades ago) a (used) reverb unit for car use. I could see it had a spring coupling two magnetic transducers, one would induce a magnetic field (audio signal) to vibrate the spring and a similar one would change the vibrations back to an audio signal. Never used it, just looked simple.

Jack

[jtougas[_2_]]

Scott -

Is there any way to determine from the rest of the circuit what values the reverb tank should be?

I seem to have lost my original tank...

- John

[Mike Rivers[_2_]]

On 5/9/2017 4:32 PM, jtougas wrote:

Is there any way to determine from the rest of the circuit what values the reverb tank should be?
I seem to have lost my original tank...

"Lost" as in "I know it's around here somewhere" or as in "The original
one doesn't work any more?" If it's the latter, are you sure the spring
unit is what failed and not one of the bucket brigade chips or other
electronics driving it?

I read something on Gearslutz about that unit and it mentioned a 4 inch
spring unit. I've never heard of one that small, only the big and the
little ones from Accutronics (Hammond), though it might have been a
Japanese-made part.

If you can fit a 9" Accutronics in the box, you might just buy one and
try it. They're only about $20, and if it doesn't work, you could make
something else out of it. Craig Anderton used it in his Electronics
Projects for Musicians book from 1975. I built one of those and it was
actually pretty good. You could get an Ampex AG-440 for about $500 and
use it as a pre-delay.

https://www.amplifiedparts.com/products/reverb_tanks






--

For a good time, call http://mikeriversaudio.wordpress.com

[Mike Rivers[_2_]]

On 5/9/2017 4:32 PM, jtougas wrote:

I seem to have lost my original tank...

Or, if you can find 5 volts in the box somewhere, you could certainly
fit one of these in the

https://www.amplifiedparts.com/produ...files_and_docs

It certainly can't sound any worse than a 4" spring, though that may be
part of the charm of this unit.


--

For a good time, call http://mikeriversaudio.wordpress.com

[Mike Rivers]

There seem to be two common configurations, one with an input impedance of around 10 ohms that can be driven by the speaker output of an amplifier, and the other with an input impedance of around 2.5 k Ohms, which can be driven by practically anything. They all have a pretty low output impedance so they can drive anything.

I suppose that they differ all over the place regarding sensitivity (volts out for volts in), so if you can't find the original part, you'll just have to cut-and-try. At the risk of it sounding too good, you can probably get one of those digital "springless" replacements that I pointed to in another post to work without too much trouble. There are a few different models that, as far as I can tell, only differ in how they're mounted (PC flat or vertical or screw mounted).

[Phil Allison[_4_]]

Mike Rivers wrote:

------------------


There seem to be two common configurations, one with an input impedance
of around 10 ohms that can be driven by the speaker output of an amplifier,
and the other with an input impedance of around 2.5 k Ohms, which can be
driven by practically anything. They all have a pretty low output impedance
so they can drive anything.


** Not quite true.

The input and output coils of reverb tanks are inductors, so the impedance rises with frequency right across the audio band. The numbers quoted in the published data are for 1kHz only PLUS the normal input power level is less than 10 milliwatts.

The 8ohm input types cannot be driven direct from an audio amp, it would massively over power them. Output impedance values vary from a few hundred ohms to a few thousand at 1kHz.


..... Phil

[Scott Dorsey]

In article ,
jtougas wrote:
Scott -

Is there any way to determine from the rest of the circuit what values the reverb tank should be?

Probably.
But if it's an Accutronics tank, you have something like five different
choices for input impedance, five different choices for output impedance,
a bunch of choices for reverb time and there are I think four different
models with different numbers of springs.

But, if it's an Accutronics tank, you can just call up Accutronics and they
will know which model you need to order.

If it's a weird Japanese tank, then putting an Accutronics tank in it won't
match the original, but you could likely find something with the right
impedances and with whatever reverb time you happen to like the sound of.

I seem to have lost my original tank...

How did that happen?
And how did this 20-year-old thread get resurrected?
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."