Testberichte (2/4)

Produkttest: Soundkarte «Prelude 1.0»

A Zorro-II 16-bit audio sampling, mixing, and playback card capable of sampling/playback rates up to 48kHz.

AUTHOR/COMPANY INFORMATION

Name:	Albrecht Computer Technik
Address:	Seth 2
	21769 Lamstedt
	Germany
Telephone:	+49-4773-8910-73
FAX:	+49-4773-8910-72
E-mail:	info@act-net.com
World Wide Web:	www.act-net.com/index.htm
Fido Net:	2:241/205
SMS:	+49-1727-6148-05

LIST PRICE

I purchased Prelude directly from A.C.T. in Germany. Note that these prices reflect the German 15% Value Added Tax (VAT), so prices are lower for customers outside of Germany. (aside: the software pack consists of drivers, sampling/playback/mixing/etc. applications, and developer code.)

Option 1	Option 2	Option 3
Prelude audio card	Prelude audio card	AudioLab16 for Prelude
Included software pack	Included software pack
DM 380	DM 410	DM 225

Seeing as there was a new version of Samplitude, I chose Option 2.

On 4/9/97, the exchange rate was DM 1.68 to US $1.00, so I paid $211.95 dollars. Prices shown above do not include shipping. (Air Mail shipment to the United States came to around US $40, or DM 70.)

At the time of writing, there is a 2-3 week production turnaround on the cards. No distributor has been named to date, but A.C.T. is interested in distribution. For more information, contact Marc Albrecht at A.C.T.

DEMO VERSION

None.

SPECIAL HARDWARE AND SOFTWARE REQUIREMENTS

HARDWARE

Any ZorroII/III Amiga. (According to Thomas Wenzel's Prelude web page, it works on both an Amiga 1000 & Amiga 500 with a simple passive adaptor. Since I don't own either an Amiga 500 or 1000, I was unable to verify this.)

48kHz stereo possible on a standard 68000 Amiga; 68020 recommended.

512k RAM required for sufficient double buffering, 2MB FAST RAM strongly recommended by the manufacturer.

Hard Drive recommended, but not required.

SOFTWARE

Amiga OS 2.04 or higher required.
Works fine on Amiga OS 3.1.

COPY PROTECTION

None.

MACHINE USED FOR TESTING

• Amiga 2500/030, 16 MB Fast RAM, 1 MB Chip RAM
• Kickstart v40.63, Workbench v40.42
• PicassoII w/1MB RAM
• A2320 Display Enhancer
• A2091 SCSI Controller, Rev. 7 ROMs w/170 MB Quantum hard drive
• Sony 15sf multisync monitor
• AIR external 1.76MB High Density floppy
• GVP ioExtender
• Chinon CDX-535 SCSI 2x external CD-ROM drive

Prelude comes in a thin black box, wrapped in bubble pack, with foam padding on the top and bottom of the card. No warranty or registration card was included.

The construction of the card is good; a professionally manufactured multi-layer printed circuit board. No version, model number, or date was on the card.

Hardware installation is straightforward. The card installs firmly but easily into any free ZorroII/III slot. It took me about 20 minutes, since I had to remove my old SupraRAM 2000 memory card in order to free up a slot.

Once the card is in place, simply plug the included adaptor into the DB15 connector on the back of the card, and connect the inputs and output to your corresponding outputs & input.

Prelude uses the standard Installer utility, making installation quick and painless.

REVIEW

I've been following the Prelude audio card since I first saw it announced in the Amiga Web Directory a little over a year ago. It has been in development (limited to spare time) for over two years.

In my case, Air Mail shipment from Germany took a week to arrive; shipped 4/10/97, arrived 4/17/97.

HARDWARE

+-----------------------------------+
|          Quick Glossary           |
+-----------------------------------+
|CODEC = COmpression/DECompression  |
|ADC   = Analog to Digital Converter|
|DSP   = Digital Signal Processor   |
+-----------------------------------+

At the heart of Prelude is a Crystal-brand multimedia codec chip (model CS4231A). Some features of this chip listed on Crystal's web site are:

• ADPCM Compression/Decompression
• MPC Level 2 Compatible Mixer
• Dual DMA Registers support Full Duplex Operation
• On-Chip FIFOs for higher performance
• Selectable Serial Audio Data Port

Unlike a DSP, this chip is designed solely for handling audio. While it can perform most of the same functions as a DSP (in regards to audio effects), it cannot for example, off-load your CPU when playing back an 8+ channel ScreamTracker (#?.s3m) MOD file, nor could it be used for something other than audio; like emulation of a 28.8 modem. Both of these functions could be accomplished with a DSP. [Although a DSP add-on is already planned].

- THE INPUTS/OUTPUT -

The information below describing the four inputs and output was sent to me by Thomas Wenzel, and is included here since it explains them well.

+-----+----------------+----------------------------+
|     | Can be used for|                            |
|     +------+---------+                            |
|Input|mixing|recording|Recommended Usage           |
+-----+------+---------+----------------------------+
|LINE |  x   |    x    |recording line level signals|
|MIC  |      |    x    |recording w/STD microphone  |
|AUX1 |  x   |    x    |CD-ROM output               |
|AUX2 |  x   |         |Amiga output                |
+-----+------+---------+----------------------------+

MIC:
can only be routed to the ADC, not to the mixer. It can be used for recording only; signal may be line or mic level.

AUX1:
can be routed to the ADC and the on-board mixer. This input can be used for recording or for mixing the audio output of a CD-ROM drive.

AUX2:
can only be routed to the mixer; you can't use it for recording. This input is recommended for mixing the Amiga output. After a reset (power on or warm reboot), when the card is not initialised by the mixer program, LINE out is muted and the source connected to AUX2 can only be sent to the mono output.

OUT:
goes to stereo system.

On the Prelude, mixing means that the signal of that input can be mixed to the output along with other inputs, and the sound generated by the codec itself.

Recording on Prelude means that you can directly record to RAM or Hard Drive from that input and you can also use it for digital realtime effects.

On the bracket edge of the card is a 15-pin D-SUB connector which has the LINE output and all four inputs. A customizable adaptor is included. When you order Prelude you can choose which type of connector you want for each input [e.g. Phono (RCA), 1/4" Phone plug (6.35mm), 1/8" Phone plug (3.5mm), etc.]

There is a jumper on the top edge of the card to feed the mono signal to a simple onboard amplifier. The output of that amplifier is available on a 2 pin connector for a small standard 8 ohm speaker. This is handy if you want your Amiga to be able to "beep"... (speaker not included) :)

The Prelude has a 40-pin (male) expansion bus connector appropriately called the "Prelude Bus". While no modules using this bus have been released to- date, the following expansion modules have already been planned:

• Digital Input/Output [S/P-DIF] (for DAT, CD, MiniDisc, etc.)
• Sample rate converter
• MIDI interface
• MPEG Decoder (supporting Layer I & II MPEG streams)
• DSP add-on
• Wave Table

Realtime F/X:

(Karoake, Echo, etc.)  [in development]
u-law, A-law, ADPCM encoder/decoder: [in development]

Note that these audio compression formats are supported by the Prelude hardware, which should provide an increase in speed.

Prelude Surround Decoder v1.1:

Allows you to adjust the gain, balance, front & rear volume, as well as the overall volume. A realtime "vectorscope" display shows where the audio is being projected (i.e. left/right, front/back.) This enables you to calibrate your surround sound.

PreludeMixer v1.0:

Implemented as a commodity, this has sliders that let you adjust the level of each input:

Line, Aux1, Aux2, Wave, Mono

There are "Lock" check boxes for each of the inputs, which keep the left and right sliders together as you adjust the input levels.

[Note: A.C.T. is working on a 4-channel software mixer.]

GFXPreludeMixer v1.1:

This alternative mixer is intended for people who prefer a stereo-system look to mixing. Note that the interface is designed for a 4-color Workbench, so if you're using MagicWB, you may find the GUI a little difficult to read, until it is fixed.

[Note: the label readability issue is being corrected]

Tapedeck v0.49:

The Tapedeck allows recording one of three inputs at a time (switchable): LINE, AUX, and MIC. The GUI (similar design as GFXPreludeMixer) looks like a DAT deck, and features Play/Pause, Stop, Fast Forward, Rewind, Record, Eject (selects/changes file), and jump to beginning/end of the sample. It also lets you adjust the frequency, gain, and peak. [Note: still in development. Several features unimplemented, buggy]

Dub! Prelude Full Duplex Recorder V1.0:

Dub! allows you to record and playback a file at the same time; also known as "OverDub sampling". It uses a GUI with the following options: Frequency (5-48kHz), Mode (8/16/U-Law/A-Law/ADPCM), with Play, Pause, and Record gadgets.

PreludeReset:

A CLI command that initializes the Prelude hardware on startup. This resides in SYS:C and is called from the User-Startup sequence.

PrlCheck v1.0:

Another CLI command (can be stored anywhere) that checks various aspects of the Prelude, such as the register status, FIFO and interrupts, as well as performing an autocalibration cycle.

Samplitude Prelude v3.0: [supplied if you bought the Samplitude bundle]

Samplitude Prelude is a specially compiled version of Samplitude Pro v3.0 for Prelude. This is a very powerful program, and has most, if not all of the features you'll need when dealing with audio. One feature that would be nice though is Sun Audio (.au) import/export.

[Note: Samplitude is being ported from Manx to SAS/C; known bugs will be fixed, parts of the GUI are being redesigned, (now totally GadTools!) and there will be some new features such as volume envelopes for virtual projects.

Audio Hardware Interface v4.0:

Good things come in small archives. If you're not already familiar with AHI, it is Retargetable Audio for the Amiga. AHI provides access to a growing array of audio applications and is highly recommended.

Note that when playing back 4 channel MODs via AHI, they will sound a little distorted or 'fuzzy'. Thomas Wenzel explains why:

"The Amiga chipset can play back four channels each with a completely independent frequency. With a standard soundcard this is not possible. Each channel has to be resampled in realtime to match the fixed playback frequency of the card. Unfortunately there's always some quality loss during resampling. There's almost nothing that can be done about it."

AHIRecord v1.3:

Provides audio monitoring and recording using AHI. A very nice GUI; clean, easy to use. Features stereo realtime audio monitor and recording level meters, adjustment of input gain and monitor volume, selectable sources for input and monitoring, adjustable frequency, and can save samples in AIFF, MAUD, or WAVE formats.

Play16 v1.7:

Simply (IMHO) the best audio player on the Amiga. Plays most major file formats easily, and can also (with some possible delays) playback audio directly from your Audio CD's (requires Asimware CDFS v3.x). Note that this probably requires an '060 to get realtime playback off an Audio CD.

Freeware; and well worth rewarding the author for a job well done and keep him encouraged to release more updates! :)

DOCUMENTATION

While early Prelude documentation was a little poor due to being rushed, new documentation is forthcoming in the form of a complete printed handbook.

Samplitude's documentation is photocopied since SEK'D suffered a severe data loss and had to resort to photocopied pages.

Samplitude's docs (34 pages total) are reduced print, (2 pages side-by-side) on A4 paper. Page 6 was missing from my set. The printed docs are for Samplitude ProII. The included docs however are close enough to the Prelude version that you can still find your way around.

LIKES

Some of the included software uses GadTools, and is well written. It's responsive and a full install only uses about 500k of free hard drive space. It comes with enough software tools to utilize all the features that a standard Prelude offers.

Prelude supports Martin Blom's Audio Hardware Interface (AHI) drivers, and in doing so taps a growing software base. It also encourages other programmers to develop for this retargetable audio system.

Prelude is, (as of this writing) the only Amiga audio card with four inputs (three mixable). Using three inputs with other Amiga cards requires a switch box; even then you would not be able to mix all three inputs simultaneously.

Prelude is also the only existing Amiga audio card with an expansion bus/connector allowing you to add an extra module to your card.

DISLIKES AND SUGGESTIONS

Inexpensive PC "Multimedia" microphones cannot be used in the 'MIC' input unless they are boosted with a small power supply or amplifier. Any microphone that has it's own power supply will also work fine (e.g. dynamic microphones). [Note: A microphone that works well is the Sony DR-30PCAMP computer headphone & microphone. It sports a microphone with a built-in amplifier that outputs -15dB when turned on; providing decent output level for Prelude's MIC input. I mention this microphone here, since it is one of the few multimedia microphones I know of that has it's own built-in amplifier.]

Prelude uses a dedicated audio chip instead of a DSP. While the cost would have been higher, the power and flexibility of a DSP could be beneficial and would open up possibilities for a variety of applications. [Note that a DSP/MPEG encoder add-on is planned for Prelude, though.]

Some software has yet to be released (Realtime FX, u-law/A-law/ADPCM encoder), and some software is still in development (TapeDeck) but A.C.T. is aware of this, and is working on it.

COMPARISON TO OTHER SIMILAR PRODUCTS

While the closest product is probably Toccata, Prelude is full duplex, boasts two extra inputs, a special expansion bus connector, and supports surround sound. It also has realtime effects like Karaoke and Echo [Note: software still in development].

This isn't the first 16-bit audio sampler that I've used (I used to own a Clarity16 audio sampler cartridge). Yet the benefits of having the hardware on a Zorro card far exceeds anything that plugs into the parallel port.

The ability to redirect both CD-ROM and Amiga audio while keeping a microphone and line-in source plugged into it is a big advantage. Your parallel port remains free for other uses, and you can mix three of the four inputs to your heart's content.

BUGS

No known hardware bugs as of this writing. Remember to check A.C.T.'s Prelude web site for software updates.

VENDOR SUPPORT

Vendor support has been very helpful, open to suggestions, and quick in responding.

For questions regarding Prelude's pricing, distribution, or the prelude shared library, contact Marc Albrecht at: marc_albrecht@act-net.com

For technical questions or AHI & Prelude interaction, contact Thomas Wenzel at: thomas_wenzel@act-net.com

Prelude software updates can be obtained from: http://www.act-net.com/Prelude/

For questions regarding AHI contact Martin Blom at: lcs@lysator.liu.se

AHI software updates can be obtained from: http://www.lysator.liu.se/~lcs/ahi.html

WARRANTY

None.

CONCLUSIONS

The Prelude audio card performs as advertised. If 16-bit audio appeals to you, I recommend the Prelude. Prelude is, as of this writing, one of the most affordable 16-bit sound cards available for the Amiga. Prelude's price may be considered a little high for some people's budgets, but you are getting solid 16-bit audio for your Amiga that's responsive and uses system resources efficiently.

I give Prelude a 4 out of 5 rating.

COPYRIGHT NOTICE

Freely distributable

Written by Gregory Donner (24-June-97)
e-mail: gdonner@cyberlink-inc.com web: www.cyberlink-inc.com/gdonner»

   

Ausgabe 10/97