Nostalgi-fi (Mission 760i, HK6100 and Teac CD-Z5000) 
Wednesday, June 16, 2021, 14:09
Posted by Anders
This is a nostalgic look back, and experience, of an early 90's budget dream system of mine that never happened for various reasons.

Back in the late 80's early 90's In my hometown of Kalmar there was but one true HiFi retailer, HiHibutiken, which was located on Kaggensgatan 38 and was managed by the ever so patient and always very nice guys Dzintars Roske and Stephan (whose last name unfortunately escapes me, sorry Stephan).

Visiting HiFibutiken was an education, the demonstrations was first class and the explanations all made sense, it was not the standard quick sales approach, instead it built long term trust in their expertise and choice of brands but most of all they made it fun and it fueled my interest a lot, thank you!

I cannot remember how many time I stood in that place and listened to Tracy Chapman's "fast car" on various equipment and grabbing a bunch of brochures from the the names of interest at the time to fuel my dreams, names like Infinity, Harman Kardon, JPW, Mission, Teac, Onkyo etc.

It was here I first heard the Mission 760i speakers, the Teac CD-Z5000 and the HK6100 and the impressions made by these at this time stayed with me all the way up to now, and will thanks to recent developments continue to do so for some time to come.

Fast forward to 2021 when I managed to get hold of both the HK6100 amplifier and the Mission 760i speakers locally here in the western part of Sweden, in good condition and for reasonable money, the Teac CD-Z5000 was tracked down and brought from Denmark.

The speakers needed a bit of love and care, mainly concerning the filter components, but luckily I know that particular kind of people who both can and want to lend a helping hand with parts of it.

Let's start with the speakers, the Mission 760 and its subsequent variants was very well regarded in the budget category in the early 90's, and for good reasons, I opted for the "second generation" 760 called 760i which had an updated bass driver and crossover network (CN).

Before restoring the filters with modern components (but the exact same component values, of course) I needed to find out what the annoying rattling one of the speakers suffered from depended upon and fix it.

It turns out that the glue fixing the spider had lost its bond on the chassis side, so I set about taking care of that first.

It was demanding and precise surgery involving some toothpicks and some glue I found lying around, very scientific.

Rattle now gone I could form a decent opinion on the sound with the original 30+ years old filters still in place, and it was... disappointing, very dark, dull and distant, proof that the CN-components had not aged that gracefully.

Enter Engelholm Audio and my old friend Pär, he was more than happy to help me out checking the components and replace the ones that had drifted to far out of original spec. to provide the experience the manufacturer had originally intended.

Pär took care to document the process in which it became all to clear that old electronics, capacitors especially, does not stand the test of time all that well.

Original filters getting stripped:

Checking the values (note capacitance drift):

The updated filters arrive, the quality of the new components was chosen by Pär to be in line with the speaker overall, meaning not over the top but just right, a class act.

The updated filers goes in:

In the process of putting te nwe filter in I took the opportunity to document the driver labels as I guess there might be others out there interested in this:

New filters in place and... what a difference! this is more like it, tighter, brighter and more focused and detailed, I strongly recommend anyone with borderline vintage speakers to undertake the same exercise as it makes a huge difference and brings back the intended sound.

The electronics from the same era that I'm now using to provide signal and power, note that the Teac CD-Z5000 is equipped with two of the now legendary Philips TDA1541 16Bit ladder dac's, and to be sure it sounds brilliant, rich and powerful even now, as does the amp and indeed the entire setup, impressive.

Lessons learned:

30 year old budget hifi equipment can, if some care is applied, still provide a rewarding experience and the price to performance ratio is usually excellent when compared to current offerings.

Take care to update old filter components, speakers usually holds up fairly well mechanically given that the material quality is decent to start with and the environment has been kind to them, but the electronics, capacitors especially, should be checked and fixed if the speakers are this old.

I'm very happy with this, some say you should not revisit the dreams of old but I disagree, this was an eye opener and it puts things into perspective when judging new and old hifi gear.
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THAM15 measured and compared 
Monday, June 14, 2021, 19:49
Posted by Anders
Many Thanks to Markus in Germany for taking the time and effort to properly measure and compare the now 12 years old THAM15 design to a modern speaker, see details below.

Equipment used:

Software: ARTA, STEPS & LIMP
Soundcard: Creative X-Fi USB HD
Pre-Amp: IMG MPA-102
Microphone: Isemcon EMX-7150 (Class 1 FR; calibrated; Max. SPL 135 dB @ 1% THD)
SPL Calibrator: Isemcon SC-1 (Class 2, temperature- and battery-compensated; Accuracy +/- 0,5 dB)
Amp: Sinbosen FP10000Q V2; limited to 50 Vrms for the 15LB075, equaling 500 watts at the impedance minimum; limited to 94 Vrms for the 15LB100, equaling 1000 watts at the impedance minimum
ARTA Measurement Box

Measurements done in true outdoor environment (no relevant obstacles for hundreds of meters). Every measurement is repeated at least once, and data only accepted as valid if both or more curves match perfectly. SPL calibration is checked before / after each measurement.

The THAM15 is in this case loaded with a "the box 15LB100-8W" transducer from Thomann (119 €), which is considerably cheaper than the recommended B&C 15TBX100.

The comparison in 10% THD limited SPL was made against a DB Technologies S118R 18" subwoofer (~2500€) which not only has a larger transducer but also has a significantly larger exterior volume (220dm3) compared to THAM15 (187dm3), it was also designed ~10 years later, and it is a bassreflex design.

THAM15 15LB100-8W Sensitivity 2,83V GPM 1m:

THAM15 15LB100 vs DB Technologies S118R Max SPL @ 10% THD GPM 1m:

(NOTE: THAM15 is not limited by THD, 3% THD at cursor)

THAM15 Burst Decay (recomended XO @ ~120Hz 24dB/Oct):

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Top speaker thoughts  
Monday, May 17, 2021, 19:09
Posted by Anders
What could one do with B&C 15NDL88, FaitalPro HF146 and XT1464, right now I'm thinking sealed alignment, ~80dm3, in an oldschool inspired way, I know what you are thinking but I'm fully aware of the potential thermal problems, but these speakers will not see such power levels very often if at all.

By oldschool I mean wide baffle, shallow and trapezoidal enclosure, think JBL SR47XX series and similar but with a hint of modern elements, something just feel right about it, to me at least.

It is however not without hurdles, the wide baffle (~600mm) will most likely cause diffraction artefacts in the low midband, meaning well below ~1kHz XO for the 15NDL88, and the sealed alignment with a Qtc around 0.55 will mean that the f-3dB will be set around 100Hz, the excursion will not be limited by a Helmholtz function, and so on...

But why take the easy option and follow the standard 50Hz tuned BR recipe of the day when instead one can go marching with a defiant smile straight into the chasm of despair and frustration, it will if nothing else be entertaining and educational.

Let's see how this develops, right now I'm here:

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poor mans surround adventures 
Wednesday, April 14, 2021, 19:54
Posted by Anders
Long time no post, between the ongoing pandemic and two energetic kids there has not been much time to post what has been going on.

To tell the truth not that much has been going on, but I would like to show one of the mini projects there has been time for, a poor mans surround system experiment.

It has its roots in the well known and very old, very basic Hafler circuit, where the rear surround channel consist of the difference between the two existing front channels, and the center is a simple stereo sum to mono.

It it based around a 1:1 15kOhm line transformer, commonly used in audio ground loop isolator filters, which is where i got mine, other than this you need speaker terminals and RCA chassis connectors as well as a couple of 10kOhm resistors.

In this case both of these circuits operate from a standard two channel amplifier speaker level outputs, and the leave you with either center or surround line channels, all with galvanic separation.

An attempt, yet to be verified (DO NOT USE) to combine these into a one box solution is on the table and I am also trying to figure out if there is a way to get channel separation for two rear surround outputs, but this remains to be seen it it can be realized (I'm a speaker nerd remember).

First the rear surround channel:

Then the center channel:

And lastly the untested, unconfirmed and "not recommended to try" alternative, do not use, I put it here just to show where I'm at.

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Locally sourced power 
Monday, December 9, 2019, 20:01
Posted by Anders
I figured I needed to try out the labgruppen LAB1600 since I have read positive comments about their sonic performance in various forums, both international and domestic, hopefully I can get my hands on two more since they should also be a good match for the ROAR15's if running them bridged amounting to ~1,6kW/driver (FTC 8 Ohm).

LAB1600 on the far left.

Initial low level listening confirms this, as a top amp (>150Hz) it sounds very good indeed, clean, detailed and controlled, and as sub amp it keeps this signature and tightened thing up significantly, more definition and punch to put it bluntly.

In my search for the LAB1660's I had the good fortune of running into another very interesting model from from labgruppen, the LAB1500, this is a rather rare model, I have yet to find any documentation online for it and have requested it from labgruppen.

The LAB1500 is a proper old school beast where 2/3 of the amp is made up of it's power supply with one of the biggest transformers I have seen to date in an amplifier, everything is arranged very neat and tidy, looks hand built, I which I could listen to it but it trips my 10A breakers when I so much as look at it (a fix for this is on the way, i hope) :)
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