What’s new in author’s audio garden?
Good news This is long running stuff – no new purchase was necessary.
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.
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
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.
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.
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”
Update on 17 April 2015 :Added 3 more photos of visual Pioneer SX-34 modification