This is a review and detailed measurements of the Lexicon, first generation DD8, 8-channel amplifier. It was purchased used by a member and drop shipped to me. The DD8 came from collaboration of Harman with TI (chip company) to produce very low weight, switching amplifiers for BMW car audio system. It was then later repurposed in this configuration for the Custom Integration (CI) industry. It is actually rebranded by a number of companies and sold under their label.
Note: our company, Madrona Digital, is a dealer for Harman products which includes Lexicon. So keep potential bias in mind as you read this review.
All 8 channels are provided in one compact, very cool running 1U rack mount chassis:
A stout on off switch manages power duties together with heftiest relay sound you have heard! The back will seem unusual for hi-fi market but is precisely what the custom integration channel needs:
You can either feed the unit individually per channel or a "bus" input that feeds the same stereo input to all the channels. The latter is very handy for "whole house audio" where the same music plays in every room from ceiling speakers and such. A looped bus output is provided to cascade more of these units.
Output is provided through phoenix connectors which again is common and desired in CI channel as they are secure but small connectors. Individual gain controls are provided for every channel. You can also select mono vs stereo (again, useful in whole house audio where you usually want mono). And auto-sensing for channels not used. Trigger is also provided of course.
The available units are pulled out of existing installs so likely have many hours on them. And if the installer didn't know what he was doing, it may have been subjected to high temps. Indeed the first unit the owner bought did not work right, changing its gain with temperature. I traced it to the front-end of the unit. So know what you are getting if you buy them used.
Brand new, second generation DD8s cost US $3,500 (through dealer channels). This version listed for US $2,500. I see them listed for $1,300 right now on ebay but I believe the owner was able to get it much cheaper.
Lexicon DD8 Measurements
As usual, we start with our dashboard. I set the gain to max which nicely gave me 29 dB which is what I have standardized on:
This is above average performance with distortion kept below 100 dB;
Noise performance is good as well:
Ideally we would get 16 bits at 5 watts but 15 is a good effort.
I was disappointed by the early cut off from the output filter:
This is due to rather low switching frequency of 250 kHz (common values are in 300 to 400 kHz), which made the filter harder to design:
Crosstalk is fine:
Power into 4 ohm is rather low:
The protection circuit was aggressive which made getting max and peak power difficult. Still I managed to get some numbers:
While we get more burst power courtesy of power supply designed for a lot more channels than two, max power with 1% THD+N still was rather low.
I then tested the amp using 8 ohm and surprisingly, it produces more power there:
To see how the power scales, I measured max power using two and four channels. Both were the same using 8 ohm:
Most disappointing was varying the frequency and producing a power sweep:
As you see, there is huge penalty at higher frequencies. Furthermore, there are power related linearities.
Conclusions
In mid to low frequencies, the DD8 produces well above average performance. Above that frequency though, distortion increases substantially and other non-linearities surface. Output seems to have some load dependency while also rolling off early.
If you can get the unit for a few hundred dollars, then its compact enclosure and general performance may be a steal. You could almost push me to recommend it but I am not going to. I like to see better performance with respect to frequency response and high frequencies. I think for its intended custom install market, it is perfect (our company has installed a lot of these). For hi-fi use, you have to make that decision.
------------
As always, questions, comments, recommendations, etc. are welcome.
Appreciate any donations using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
Note: our company, Madrona Digital, is a dealer for Harman products which includes Lexicon. So keep potential bias in mind as you read this review.
All 8 channels are provided in one compact, very cool running 1U rack mount chassis:
A stout on off switch manages power duties together with heftiest relay sound you have heard! The back will seem unusual for hi-fi market but is precisely what the custom integration channel needs:
You can either feed the unit individually per channel or a "bus" input that feeds the same stereo input to all the channels. The latter is very handy for "whole house audio" where the same music plays in every room from ceiling speakers and such. A looped bus output is provided to cascade more of these units.
Output is provided through phoenix connectors which again is common and desired in CI channel as they are secure but small connectors. Individual gain controls are provided for every channel. You can also select mono vs stereo (again, useful in whole house audio where you usually want mono). And auto-sensing for channels not used. Trigger is also provided of course.
The available units are pulled out of existing installs so likely have many hours on them. And if the installer didn't know what he was doing, it may have been subjected to high temps. Indeed the first unit the owner bought did not work right, changing its gain with temperature. I traced it to the front-end of the unit. So know what you are getting if you buy them used.
Brand new, second generation DD8s cost US $3,500 (through dealer channels). This version listed for US $2,500. I see them listed for $1,300 right now on ebay but I believe the owner was able to get it much cheaper.
Lexicon DD8 Measurements
As usual, we start with our dashboard. I set the gain to max which nicely gave me 29 dB which is what I have standardized on:
This is above average performance with distortion kept below 100 dB;
Noise performance is good as well:
Ideally we would get 16 bits at 5 watts but 15 is a good effort.
I was disappointed by the early cut off from the output filter:
This is due to rather low switching frequency of 250 kHz (common values are in 300 to 400 kHz), which made the filter harder to design:
Crosstalk is fine:
Power into 4 ohm is rather low:
The protection circuit was aggressive which made getting max and peak power difficult. Still I managed to get some numbers:
While we get more burst power courtesy of power supply designed for a lot more channels than two, max power with 1% THD+N still was rather low.
I then tested the amp using 8 ohm and surprisingly, it produces more power there:
To see how the power scales, I measured max power using two and four channels. Both were the same using 8 ohm:
Most disappointing was varying the frequency and producing a power sweep:
As you see, there is huge penalty at higher frequencies. Furthermore, there are power related linearities.
Conclusions
In mid to low frequencies, the DD8 produces well above average performance. Above that frequency though, distortion increases substantially and other non-linearities surface. Output seems to have some load dependency while also rolling off early.
If you can get the unit for a few hundred dollars, then its compact enclosure and general performance may be a steal. You could almost push me to recommend it but I am not going to. I like to see better performance with respect to frequency response and high frequencies. I think for its intended custom install market, it is perfect (our company has installed a lot of these). For hi-fi use, you have to make that decision.
------------
As always, questions, comments, recommendations, etc. are welcome.
Appreciate any donations using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
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