What’s new in my audio garden – 07-2019

What’s new in author’s audio garden?


Good news :) This is long running stuff – no new purchase was necessary.

panorama C


I was improving and simplifying my stereo within last months. Measurements started to be as they should be – right looking and complying to listening impression. It was main success but also surprise as I am declared against to measurement heaven.

Following is one of column recordings done with studio class microphone  in a distance about 3 meters from speaker column in normal living room.


A) Decided that turntable preamp shall only be the one incorporated in Pioneer SX-34. I found tube „phono” preamp as giving a stronger more reach sound, even I am not able to support this. For the purpose of using tube phono  preamplifier I had to match volume output signal with input sensitivity of AUX in Ouverture and also Onkyo TX-906. As Pioneer output for tube tape recorders is deliberately lowered by resistance division, this division I altered to balance to the one required by me. Due to always observed unwanted change of frequency characteristic at recording output I did about 20 pF/200 Kohm compensation of decrease above 7 kHz to secure identical signals. Also fine checking of two ECC 83 stages, revealed that applied original resistances were not accurate, varying up to 25% of currents and voltages. This was resulting in noticeable non-compliance to IAA curve at output. After rectifying this problem by  matching the resistances and voltages to original diagram it decreased to negligible level.


B) Simplified and rearranged system connection in compare to that from 2013


In my judgement Luxamn L210 does not enough in compare to Onkyo TX 906 so is now in „reserve sit”.

Now by simple switching of remote controls , manual switching of Manual 1,Manual 2 and Manual 3 – (see attached drawing) it is possible to:


1. Listen to turntable with original system of Pioneer tube amplifier with no remote volume control,

2. Listen to turntable with Pioneer tube preamp and Onkyo TX 906 amplifier with ONKYO volume remote control

3. Listen to turntable with Pioneer tube phono preamp, B&O volume and tone remote control and (by sending back) with tube Pioneer amplifier

4. Listen to radio stations with a) Pioneer all tubes system, b) Onkyo all solid system, c) Onkyo solid tuner / Pioneer tube amplifier d)Bang & Olufsen solid tuner / pioneer tube amplifier or e) B&O tuner with Onkyo solid amplifier, f) Pioneer tube tuner with ONKYO solid amplifier. g) Pioneer tube tuner with B&O remote tone and volume control and (by sending back) with Pioneer tube amplifier.

5. Listen to B&O CD with a) Pioneer tube amplifier, b) Onkyo solid amplifier

6. Listen to B&O cassette tape with a) Pioneer tube amplifier, b) Onkyo solid amplifier,

7. Listen to Reel to reel tape recorder with a)  tone and volume Beo4 control and with Pioneer tube amp , b)  with volume Onkyo remote and with .Onkyo solid amplifier

8. Record to tape recorder from any source coming through Bang & Olufsen (out B) (everything except Reel to reel tape recorder) with control of  recording level by remote  Beo4

9. Record from all sources connected to Bang&Olufsen to it’s cassette recorder with automatic level control.

10 When listening it is possible to watch sound levels from all sources ( comes from Bang& Olufsen output B which is serving everything  recorded to reel-to-reel) at level indicators switched to „source” position at Tesla B116. Condition – B116 and B&O are powered.

11. Play and record to cassette or reel to reel from keyboard workstation, TV satellite or PC audio output with all variety of possibilities. Btw, Keyboard workstation can also be recorded to PC.

M(A)TCH type speaker columns with systemclick to enlarge

C) Last time I noticed difference of tone performance between my  dynamic feedback tube SE  amplifier in Sonet B3 and upgraded by me to „ultra-linear tone” Pioneer tube  Push-Pull  amp. Decided to increase level of previously developed by me feedback circuitry, by bridging half of resistances in grids no3 by selected 1,47uF capacity. For this purpose the existing  in no3 grids 16 K resistances were replaced with two 8 K in serial and first of them bridged (see new schematic in „Pioneer SX-34 modification”) . More feedback resulted in better expression and less impression of quality dependency from  source frequency range, (now not different to that observed in my SE amplifier with dynamic feedback). This helped also to improve tuning of magnetic couplings and damping in my M(A)TCH speaker columns and that all resulted in significant upgrade – very noticeable in direction to reality,  specially for old vinyl plates sound. And this old recordings may be considered proof of basic balance . This success is the reason why now I resigned from buying better class B&O pickup MMC20E to Beogram 1700. I use standard MMC20S and it works in my system 99% ideal (as for my senses).

I invite interested to watch some microphone recordings in my Youtube channel Mikexception under „ultimate reality speaker system” Those familiar with acoustic  phase problems may watch same my deliberations in „Should we worry about phase distortion in speakers”

Michal Czabajski (spelling  Tchabaysky)

Gdynia 2014 -07 -06

Update 2015 – 02 – 13         Speakers With 6 Watts 1959 Drivers

Stern wide-range Stern wide-range 2

In many cases I bring peoples  attention to meaning „Wide-range speaker” as a optimum level  (rather theoretical)  of quality to which should be multi-way compared . It is not impossible to build speaker sounding like wide range – problem  is to get such wide-range driver. This drivers had their golden times in 1955 – 1965 and were used in old luxury tube radio  receivers. They differ from modern compact  with relatively small movement of cone which is important for low Doeppler and linear creation of low tones. The point is that regarding low tones the diaphragm is supposed to have big surface while for sopranos dimension is to be  small. Fair compromise were 25- 30 cm diameter drivers with two cones mechanically coupled.  This kind of driver may (example Tonsil GDS 31-26/15) cover sopranos up to 13 kHz. Unfortunately  used Tonsil  are no available – my guess is that  all are finished.  More promising are German speakers used in Stern radios – limited power of radio amp saved them from destroy. Pair of them removed from JUVEL 2 – the father of Stradivari I purchased last November together with cone tweeters covering sopranos. To achieve perfect effect this speakers need unique boxes with no resonances . The basic of operation of this type is to get futures similar to flat plate  and to separate back from front – so called damping barrier. No low resonance is provided.  To cover higher sopranos   cooperate with them original  cone tweeters and the 6 dB cross frequency was tuned by me. Original used by „Stern Radio Lipzig”  capacity 2000nF value (after removal all unwanted resonances which were standard in old radios)   I decreased to 490nF so the cross frequency is lifted to about 14 -15 kHz. For such high level  phase distortions are not to be recognized nor weighting and in my opinion this speakers reflect meaning „wide- range”. And what is most important for me it is heard  in sound. The result as expected from the beginning   by me is even better  than presented earlier bigger and much more complicated MATCH. The  disadvantage is that this marvels cannot be replicated.

Stern wide-range 3

Update 29 March 2015 – new schematic diagram for Juvel2 speaker system

      As I mentioned many times, process of listening/auditing to reach  the right sound needs a lot of testing with brakes. In my search for original data I found two versions of schematic diagram for German radio Juvel 2 . With different two values of separating capacity between wide-band and tweeters (which originally  were  two in serial per one wide-band – see file about Stern Radio  old speakers). One value was 2000nF and other 1000nF. As I use one tweeter  – one wide-band  only, this had to be redesigned. Value 2000nF shown to be faulty by ear tests. . Then I set my own concept of serial resistance 39Ohm (27 Ohm+tweeter 12 Ohm)  and 490nF – see above. T=RC was 19,1 which means cross frequency 8,33kHz and small loudness.

       After discovering other  diagram  I tried another combination which for one tweeter follows basic concept of cross-frequency  provided in Juvel 2, it means total 24Ohms resistance in speakers working with 1uF capacity. Cross frequency: T=RC=24 which means cross frequency 6,62kHz. I had to modify it to  resistance=17Ohms ( 5 Ohms +12 Ohms tweeter)  working with  capacity 1,411uF to preserve the original  sound pressure of two tweeters. Cross frequency:T=RC= 23,98 which means 6,64kHz. By ear result became  perfect.

       Now I am wondering : how come that German Stern Radio was so wise to make so perfect audio set in 1956???? (1956 was year of presentation of  this radio).  If fact I have no answer – could it be that in this years their  approach was more artistic  than our  today ?? Anyway my respect for Stern Radio speaker engineers.

Michal Czabajski

Update 15 April 2015     New image for Ampliturner

Alteration of  view of Ampliturner outside I already started long time ago. Now I did quite big step ahead. To see details You may check part „Pioneer SX-34 modification and other author’s audio stuff”


And with  „old fashioned style”

PIC01125.JPG PIC01127.JPG PIC01131.JPG

Update on 17 April 2015 :Added 3 more  photos of visual Pioneer SX-34  modification

Update on 12 November 2017 : New system arrangement

   It’s been two years since I presented an arrangement of my audio system. Due to new elements it is already redesigned.

Philips N4506


    I did serious renovation of reel to reel Philips N 4506 tape recorder. Incorporated inside inputs mixer together with magnetic phono input for plate opened possibility to simplify the manipulations and grouping all together. And shorting all cabling as much as possible is always welcomed too.


Now system is equipped with two reel to reels – Philips N4506 for normal play/recording operation of tapes due to it’s higher rewinding speed and perfect adjustment of stress  in tapes, and Tesla B116 mostly for playing tapes recorded with the same model of Tesla placed in distance.


Two amplifiers are used as before – one for daily use is Luxman with wider a bit less vivid sounding and Pioneer SX34 with a bit more energetic sound – both have parrarel input connection to output from B&O Ouverture and only speakers are manualy switchable as desired.

Audio system

B&O automatic turntable has been equipped by me with elyptical pickup and is connected to Philips reels phono input with surprisingly good complementary .


Another advantage became shifting of PC sound card near it’s Philips input   and the longest transmission cable from PC is digital. All this has made a positive changes which after adopting them in speakers unveiled again benefit in reality. 

July 2019


In last  two years I upgraded some parts of system. First serious change was revitalization of Loudness Compensation  to all amplifiers. I followed the solutions provided by Germany’s Uher in their Royal de Luxe reel and Uher CV140 amplifier. I  replaced bulky Philps N4506   reel recorder  with purchased vintage studio class Uher described in other post . All mixing and switching operations I  passed to purchased last year also vintage unique amplifier Uher CV140. This one deserves separate description, may be later.   With proper Loudness compensation I discovered that any modification to output stage i Pioneer was no longer justified – conversion was removed back to original. Outer look was redesigned again to secure smaller front plate. Also Luxman L210 had been carefully tuned in output bias  – thanks to this I could better equal .sounding of both channels  I also overhauled  turntable as it was never done by me and was already 36 years old. Hopefully  everything was no problem. I did only small increase of antiscating force just up to my long time impression.  Unfortunately this I can’t check in adviced  way because not available for me special LP for this purpose is required.

DSCN1173 DSCN1189 DSCN1199 DSCN1160 DSCN1193 DSCN1169 DSCN1157  DSCN1161DSCN1170 DSCN1205 DSCN1200 DSCN1203 DSCN1204


Previous sensors                           Actual sensors

I present also few modifications –

1. unit with volume indicators useful to  measure  volume of monitored signal during recording.

2.  printed plate with system DSS which  I developed many years ago – this system applicable to reel to reel recorders adds reality due to slight  timbre compensation to two way speaker system which I reconstructed   also last year.

3. Fixed axe sensors for measuring tape tension were modified according to more sophisticated version developed in past by producer.

4.Lighting to mechanical  tape counter.

5. stickers with information about tracks and channels added to original  signalization of replay and record


New image of Pioneer SX34.








A „new” two way speakers use two Pioneer licence 16 cm diameter midwoofers capable to work to 9 kHz and two Tonsil cones capable by tech specs  to 16 kHz.  I confirmed that they reproduce to 19 kHz. The box is closed and sealed  type originally developed  by Tonsil but crossover system is redesigned by me and it is  of kind  not used in known to me speakers.  . Also front of speakers with resonating tweeter’s chamber was developed by me   Simplified measuring with industrial microphone unit. unveiled that low range starts as low as 25 Hz.






57 myśli nt. „What’s new in my audio garden – 07-2019

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