We say...
A pre-owned Metasonix RK4 in good condition. It comes with original packaging and power cable
Manufacturer's description
The RK4 is the minimized version of our R-54 Supermodule,
boiled down to a single 8hp module with a single vacuum tube.
It uses a triode-pentode in a unique Wien-bridge circuit, to provide clean sine-wave oscillation. Using a Vactrol, the pitch of the RK4 is sweepable from less than 20 Hz to more than 2 kHz, continuously, via front-panel control or a CV input. By adjusting the waveshape/resonance control, the sinewave signal produced by the RK4 can be trimmed to less than 10% THD (depending on operating pitch)—with NONE of the problems inherent in solid-state oscillators and sine waveshapers. Because the Wien bridge contains no piecewise sine shaper or amplitude-control circuit or component. The tube itself performs that job. So the distortion products are entirely low-order, unlike the “sine waves” that solid-state VCOs or samplers produce.
Turn up the RESONANCE, and the oscillator output gives a unique soft-clipped square-wave sound. The simplicity of the RK4 will fool you–its behavior is odd and radical, and years will be required to fully explore all of its quirks.
Now for the special trick. Plug an audio signal into the audio input. Instantly, the RK4 transforms from a VCO into a bandpass resonant voltage-controlled filter, with the same range as in VCO operation — 20 Hz to >2 kHz. Its behavior and sound are unique. Again, you will be kept busy for years exploring all of its strangeness.
CV response: Hz/v. Maximum output signal, 12 v p-p. Power requirement: +12v dc, approx 400 mA, and -12v at 10 mA. As with all our modules, it draws about 2.5 times the operating current during “cold” power-up, and you must insure your power supply can handle the inrush current. See our support section for more information and power supply suggestions.
(All specifications are approximate and may vary from sample to sample.) Tube used: 6GH8, 6U8, 6CQ8, ECF82 or other compatible types.
How much is my shipping?
Shipping is automatically calculated before you submit your payment information. Simply add items to your cart and proceed to the checkout page, where you'll be offered shipping options and their prices. In the UK, 'next working day' shipping is free if the order value is over £150, and £5 otherwise. We can also ship on a 'next working day before 12pm' service, which costs £6 for orders over £150 and £7.50 for orders under £150.
Shipping to mainland EU typically costs between £7 and £20, depending on the shipping method and the size and weight of the order.
Do you ship to my country?
Almost certainly - the site will give you an estimate of shipping costs if you add an item to the cart and then enter your country and postcode. If you have specific requirements (such as if you prefer UPS over FedEx, for example) then let us know in advance and we'll try to work something out for you.
Shipping methods
We use a combination of DPD, Royal Mail and Parcelforce for the UK, and for international orders it's either DHL, FedEx, UPS, Royal Mail or Parcelforce depending on where you are in the world. If you have a particular preference then try to let us know BEFORE you order so we can look into it for you. Please note that there may occasionally be additional shipping charges if you live in a remote area, depending on what surcharges are applied by the shipper. We'll get in touch to discuss this with you in such cases.
Dispatch times
For UK orders, we aim to dispatch the same working day if we get the order before 16:00. If you have a really urgent situation then of course drop us an email before ordering and we'll always do our absolute best to accommodate you.
For international orders, we normally dispatch the same day if we get the order before 13:00 but again, occasionally it might be the next day before we can send it out, and sometimes the couriers may come to collect a little earlier than scheduled which would also push an order into the next day.
Saturday/Sunday shipping
If you're in the UK and you order before 16:00 on a Friday then we can send something for a Saturday or Sunday delivery with DPD. This is FREE for order values over £350, £5 for order values between £75 and £250, and £7 for order values under £75. (NB: this applies to UK mainland addresses only). Please note that any orders placed after 16:00 on a Friday will ship on the Monday.
International shipping times
Since April 2020, the couriers we use have suspended guarantees for shipping times, so even though we're paying them for priority services - 24-48 hours for most of the world - in practice it's often an extra day on top and sometimes it can be longer. There is absolutely nothing we can do about this, unfortunately. If you are outside the UK and it's a life-or-death situation where you absolutely MUST have that passive mult for the next day then... it may be better to find a local supplier.
Pre-orders
If a product is listed as a pre-order, it means we've ordered it from the supplier but it's not physically in stock yet. The product listing will include an estimated shipping date based on the best information we have from the supplier, but do bear in mind this is subject to change and is not a guaranteed date.
If you place an order containing a mixture of in-stock and pre-order items, we'll normally hold off on shipping anything until the pre-order item(s) have arrived, rather than splitting it into multiple shipments. If you need the in-stock items sooner, we'd recommend placing separate orders. As always, please get in touch if you have questions.
Product Overview
We say...
A pre-owned Metasonix RK4 in good condition. It comes with original packaging and power cable
Manufacturer's description
The RK4 is the minimized version of our R-54 Supermodule,
boiled down to a single 8hp module with a single vacuum tube.
It uses a triode-pentode in a unique Wien-bridge circuit, to provide clean sine-wave oscillation. Using a Vactrol, the pitch of the RK4 is sweepable from less than 20 Hz to more than 2 kHz, continuously, via front-panel control or a CV input. By adjusting the waveshape/resonance control, the sinewave signal produced by the RK4 can be trimmed to less than 10% THD (depending on operating pitch)—with NONE of the problems inherent in solid-state oscillators and sine waveshapers. Because the Wien bridge contains no piecewise sine shaper or amplitude-control circuit or component. The tube itself performs that job. So the distortion products are entirely low-order, unlike the “sine waves” that solid-state VCOs or samplers produce.
Turn up the RESONANCE, and the oscillator output gives a unique soft-clipped square-wave sound. The simplicity of the RK4 will fool you–its behavior is odd and radical, and years will be required to fully explore all of its quirks.
Now for the special trick. Plug an audio signal into the audio input. Instantly, the RK4 transforms from a VCO into a bandpass resonant voltage-controlled filter, with the same range as in VCO operation — 20 Hz to >2 kHz. Its behavior and sound are unique. Again, you will be kept busy for years exploring all of its strangeness.
CV response: Hz/v. Maximum output signal, 12 v p-p. Power requirement: +12v dc, approx 400 mA, and -12v at 10 mA. As with all our modules, it draws about 2.5 times the operating current during “cold” power-up, and you must insure your power supply can handle the inrush current. See our support section for more information and power supply suggestions.
(All specifications are approximate and may vary from sample to sample.) Tube used: 6GH8, 6U8, 6CQ8, ECF82 or other compatible types.
Technical Specs
Shipping Details
How much is my shipping?
Shipping is automatically calculated before you submit your payment information. Simply add items to your cart and proceed to the checkout page, where you'll be offered shipping options and their prices. In the UK, 'next working day' shipping is free if the order value is over £150, and £5 otherwise. We can also ship on a 'next working day before 12pm' service, which costs £6 for orders over £150 and £7.50 for orders under £150.
Shipping to mainland EU typically costs between £7 and £20, depending on the shipping method and the size and weight of the order.
Do you ship to my country?
Almost certainly - the site will give you an estimate of shipping costs if you add an item to the cart and then enter your country and postcode. If you have specific requirements (such as if you prefer UPS over FedEx, for example) then let us know in advance and we'll try to work something out for you.
Shipping methods
We use a combination of DPD, Royal Mail and Parcelforce for the UK, and for international orders it's either DHL, FedEx, UPS, Royal Mail or Parcelforce depending on where you are in the world. If you have a particular preference then try to let us know BEFORE you order so we can look into it for you. Please note that there may occasionally be additional shipping charges if you live in a remote area, depending on what surcharges are applied by the shipper. We'll get in touch to discuss this with you in such cases.
Dispatch times
For UK orders, we aim to dispatch the same working day if we get the order before 16:00. If you have a really urgent situation then of course drop us an email before ordering and we'll always do our absolute best to accommodate you.
For international orders, we normally dispatch the same day if we get the order before 13:00 but again, occasionally it might be the next day before we can send it out, and sometimes the couriers may come to collect a little earlier than scheduled which would also push an order into the next day.
Saturday/Sunday shipping
If you're in the UK and you order before 16:00 on a Friday then we can send something for a Saturday or Sunday delivery with DPD. This is FREE for order values over £350, £5 for order values between £75 and £250, and £7 for order values under £75. (NB: this applies to UK mainland addresses only). Please note that any orders placed after 16:00 on a Friday will ship on the Monday.
International shipping times
Since April 2020, the couriers we use have suspended guarantees for shipping times, so even though we're paying them for priority services - 24-48 hours for most of the world - in practice it's often an extra day on top and sometimes it can be longer. There is absolutely nothing we can do about this, unfortunately. If you are outside the UK and it's a life-or-death situation where you absolutely MUST have that passive mult for the next day then... it may be better to find a local supplier.
Pre-orders
If a product is listed as a pre-order, it means we've ordered it from the supplier but it's not physically in stock yet. The product listing will include an estimated shipping date based on the best information we have from the supplier, but do bear in mind this is subject to change and is not a guaranteed date.
If you place an order containing a mixture of in-stock and pre-order items, we'll normally hold off on shipping anything until the pre-order item(s) have arrived, rather than splitting it into multiple shipments. If you need the in-stock items sooner, we'd recommend placing separate orders. As always, please get in touch if you have questions.
