Help needed Kit 88

[Gennymensch]

Hi,

I have an old Y 2000 Kit 88 which I have been operating more or less constantly since then.

Now I have planned to add a "pre-out" for a subwoofer connection into the device.

Can some one help me by giving advice how to do it ?

Many thanks in advance,

K.

[John Caswell]

Hi K,
I assume that this is a WAD Kit/Kat88 and not a WD 88VA but the same rules apply either way.
If the amplifier is an integrated version with a tape output then you can use this to feed the sub woofer amplifier directly as most sub woofer amplifiers have the necessary frequency contouring circuits built in.
If it is purely an amplifier then you can buy RCA "Y" connectors, sometimes called "two into one" which have two phono sockets and one phono plug (CPC in the UK sell them). The signal goes into one phono socket, the feed to the sub woofer into the other phono socket and the plug into your amplifier. That's it! You will obviously need two of these for stereo.

John

[Richard]

Originally Posted by John Caswell

Hi K,
I assume that this is a WAD Kit/Kat88 and not a WD 88VA but the same rules apply either way.
If the amplifier is an integrated version with a tape output then you can use this to feed the sub woofer amplifier directly as most sub woofer amplifiers have the necessary frequency contouring circuits built in.
If it is purely an amplifier then you can buy RCA "Y" connectors, sometimes called "two into one" which have two phono sockets and one phono plug (CPC in the UK sell them). The signal goes into one phono socket, the feed to the sub woofer into the other phono socket and the plug into your amplifier. That's it! You will obviously need two of these for stereo.

John

Hi John, welcome K,

John, I didn't wire my tape sockets and switch up, but looking at Kit88 Tape Out it seems that it wouldn't be controlled by the vol control and would give the full level out of any source selected.

If so there may be 2 other options,

1) if the sub has a high level input it can be used for connecting to the Kit88 speaker output sockets along with the speaker cables

2) if the sub's line input is fairly high impedance (>20K) it should be ok connected to the Kit88 signal input tags R GND L on the pcb. This would give a line level connection after the volume control.
As John says you could then use an un-used pair of RCA sockets such as the Tape Out ones on the back panel as sub connectors.

[Gennymensch]

Thanks John and Richard !

Yes it is a WAD Kit 88, and yes, I would prefer the Option for volume control.

So, your advice is to go directly from the volume pot into the subwoofer, no additional voltage divider (I hope this is the correct expression - I mean 2 resistors in series and the output between them) needed ?

Thanks again !

K.

[Richard]

Hi K,

As Kit88 uses a passive "pre" section the best/easiest way may depend on one or two things;

Is you Kit88 wired for all inputs including Tape In/Out and what is the volume pot is it the supplied 100k or a 47k?

What is your sub make/model?

How far away from Kit will the sub be placed?

[Gennymensch]

Hi Richard,

I dont have the sub yet, I will by an used one and basing on the opportunity I can´t be sure wether it has rca and/or loudspeeker inputs. It will be placed max. 2 mtrs away from the amp.

Regarding the Kit, I have done some modifications with it (changing parts, but keeping the original values, except the feed back which I reduced). The pot is a DacT CT2 stepped attenuator and has 100k. The amp is currently not wired for Tape in/out.

[Richard]

Hi K,

It should be fine with a short interconnect from the volume pot to the sub. Perhaps connect at the pcb and run out to 2 of the un-used RCAs on the back panel.

It is a passive pre though and the source impedance will be influenced by the volume pot so keep the interconnect short and low capacitance. There should be no need to try and match impedance as we are not transferring power. We are wishing to keep voltage and frequency bandwidth so are looking ideally for a low source impedance and a high load one.

As you are yet to get the sub you have options left there too. A sub with high level inputs may give the easiest option. I looked out the pdf of the REL T5 as an example, https://www.hifigear.co.uk/media/upl..._T5_Manual.pdf

You'll see they prefer the high level connection and supply a 10M cable to connect to your amp speaker terminals. The text also says it is high impedance 150k so it should be fine with a low level connection as we have discussed. The only thing that concerns me is just one RCA input for low level input and their suggestion to use a Y connector to join both L and R inputs. If you did that it would of course join L and R for your main amp. Other subs may have 2 RCA inputs.

So bottom line now is to choose a sub to go after and check the spec first so you can have a plan in mind


Connecting and Setting Up
High-level connection, using the enclosed cable with the Neutrik Speakon connector, is always the first
choice. This connection can be made without affecting the performance of the amplifier because the REL’s
amplifier input impedance is 150,000 ohms, in effect not producing any additional demand whatsoever on the
rest of your system. This scheme also avoids adding any detrimental effects by not interposing any additional
electronics into the amplification chain.
• The standard high-level hook up procedure is: attach the red wire to the amplifier’s right positive speaker
output terminal; attach the yellow wire to the amplifier’s left positive speaker output terminal; attach the
black wire to whichever of the amplifier’s ground output terminals is convenient; plug the Speakon connector
into the Sub-Bass System’s high-level input.
• For differential (i.e. fully balanced) amplifiers using one REL, simply use the standard connecting scheme
with the exception of connecting the black wire to chassis ground (i.e. a metal bolt or screw, preferably not
painted or anodized, on the chassis of the power amp or receiver), not to a negative speaker terminal, and
then connecting into the HIGH LEVEL INPUT on the REL. Please contact your dealer should there be any
questions concerning this or any other hookup procedure.
Low-level connection (via phono connectors) is always an option if high-level connection is not possible.When
connecting to the low-level inputs in a system in which high-level connection is not possible, connect a single phono
cable to the LOW LEVEL INPUT jack. If you are connecting two channels of stereo output from a pre-amplifier, simply
use a high-quality y-adapter to sum the two signals together.

[Gennymensch]

Hi Richard,

many thanks for your help and advice ! It was very helpful - I will follow your instructions.

Thanks,

K.