https://www.diyaudio.com/community/threads/the-germanium-only-circlotrons-powerful-wideband.325287/
Thanks for Circlotron link
Very interesting.I read today review plenty of informations about Germanium use reasons directly from the company designer.
https://www.monoandstereo.com/2020/03/salab-black-knight-reference-amplifier.htmlBlack Knight Reference = 400 Watt's
Ge Elephants in the Room !!Attachments
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Hello gentlemans,
Here is my review of the Grundig sv50 because i have seen allot of crap revievs of old Ge amps (of course wich where also good or badly implemented as nowadays) BUT from my experience is that i happened to find equally faulty old Si and newer ones hissing and shorting or buzzing as Ge parts...... so stay with me in what i have to say here about the old Grundig Sv Ge series, because believe me these are reall sleepers. So if you get one you should know what you will get and have to do. I have nothing to gain from this review because i will never sell it; i will only horder spare parts from now on.
I happend to actually have and repair a Grundig sv 50. The biggest difference is that sv 50 is the SINGLE one from the sv series that has a phase splitter transformer wich i love the most matched with Ge and is galvanically separated wich means no DC through the primary and results in a wider bandwidth...
From the construction point of view it is VERY VERY solid build with cast zinc pots and carbon cursors and wiper , 2mm solid steel case, real solid wood case, CuAg single solid copper core wires meshed in silk impregnated in rubber wich havent rottent or oxidise all these 60 years. The front push buttons are naked type contacts with solid steel and bronze wich only need a bit of cleaning and oiling. The amp thus wheights like a class A amplifier.
It has a floating ground for the outputs with custom very high ripple capacitors, AND dont be amased that if you feed just the amp with signal will equal or better your Si class A.................................
The rest of the small litics caps are crap by now and leak and needs to be replaced FAST.
The input conectors are shielded, and the vintage output conectors for the speakers are very reliable. The amp has one 220v switchable input to 110 and 5 outputs to wich you can connect all your equipment and turn all the sistem on at the same time (clever).
The mains trafo is very well made and has a solid 0.8mm belly band Cu shield and has very low mechanical noise and is well shielded but usually have rust and neds a proper clean and laq again or not.
All of the pcb's are covered in very thick bath of solder wich will outlast your life. I havent seen or heard any owner to have problems in this department.
The AD131 outputs are still very easy to find replacements (are are compensated BE and E resistors to GND or center with ferite core coils to prevent oscillations) and the service manual shows a very good way to measure and match them to the specs, but the small shitty Ac151r matched pairs (wich can be found also in old tandbergs and uher) are trully almost impossible to find. It is full of them in this amp!!!! When the output burns out it will take the input stage of the amp Ac151 with them. Here you can use regular Ge parts to change. No fuss.
Let me tell you how to handle the scarcity of the originall siemens gems.
I happend to have RO/USSR made equivallents wich are abit more noisier and have extracted the originall ones from the stages more closer to the amp where the noise doesnt matter that much and replaced them with equiv parts without any noticeable difference and kept the originall low noise 2.5db genuine Ac for spare parts, so i can sleep well and happy listen.....
The originall Selenium bridge is usually in very good shape but crap by todays standars so i replaced it with a ultra fast soft recovery with extremely good results in soundstage, definition and channel separation.
Now for the phono i do think that the phono is very solid made but it has a inbetween RIAA and CCIR standar equalisation so that you can listen to them both (but actually it is not the best for each one of them so there it needs an improvement) and is abit unclear in presentation because of the Ge on the input. So a modification designed to low noise Si usage for the input and Ge on the second stage made things very good now. (thanks Dreamth) My opinion is that Ge is very good in phono but BAD for the first stage. It is astoundingly good at supressing clics and pops (just like valves) from my very old recordings wich amased me me!
And now the last part the main preamp wich has allot of very rare Ge wich is very very well build BUT isnt that incredible because of the loudness equalisation of that period in wich the sealed speakers have had a ton of hights and a very light bass and needed conpensation.. So this sucker in the 0 (12 oclock) is giving the amp a ton of bass and fewer hights so i unsoldered one of the terminal of the loudness equalisation chain and baaam the prob was solved..
In conclusion this is a very very good sleeper amp and to my ears Ge with output or phase splitter transformer or both are in the same league as the good class A out there.
So this amp needs a ton of love and care to make it blow you to smithereens so dont underestimate the Ge amps because there were good ones and bad cheap ones wich where bad sounding and unreliable because of the implementation.
In my opinion i would not make one from scratch because it will cost way more for the same quality so better refurbish a unit! I have buyed my amp one year ago at a price of only two new Alps blue velvet pots so just think about it.....
Bellow are pics with the amp finished and a couple of pics made after the upgrades.
I have buyed it very cheap but in an awfull condition and took two weeks to bring it here (change parts, thinkering, cleaning, and restained the wood) ... You may be luckyer than me....
Cheers
Here is my review of the Grundig sv50 because i have seen allot of crap revievs of old Ge amps (of course wich where also good or badly implemented as nowadays) BUT from my experience is that i happened to find equally faulty old Si and newer ones hissing and shorting or buzzing as Ge parts...... so stay with me in what i have to say here about the old Grundig Sv Ge series, because believe me these are reall sleepers. So if you get one you should know what you will get and have to do. I have nothing to gain from this review because i will never sell it; i will only horder spare parts from now on.
I happend to actually have and repair a Grundig sv 50. The biggest difference is that sv 50 is the SINGLE one from the sv series that has a phase splitter transformer wich i love the most matched with Ge and is galvanically separated wich means no DC through the primary and results in a wider bandwidth...
From the construction point of view it is VERY VERY solid build with cast zinc pots and carbon cursors and wiper , 2mm solid steel case, real solid wood case, CuAg single solid copper core wires meshed in silk impregnated in rubber wich havent rottent or oxidise all these 60 years. The front push buttons are naked type contacts with solid steel and bronze wich only need a bit of cleaning and oiling. The amp thus wheights like a class A amplifier.
It has a floating ground for the outputs with custom very high ripple capacitors, AND dont be amased that if you feed just the amp with signal will equal or better your Si class A.................................
The rest of the small litics caps are crap by now and leak and needs to be replaced FAST.
The input conectors are shielded, and the vintage output conectors for the speakers are very reliable. The amp has one 220v switchable input to 110 and 5 outputs to wich you can connect all your equipment and turn all the sistem on at the same time (clever).
The mains trafo is very well made and has a solid 0.8mm belly band Cu shield and has very low mechanical noise and is well shielded but usually have rust and neds a proper clean and laq again or not.
All of the pcb's are covered in very thick bath of solder wich will outlast your life. I havent seen or heard any owner to have problems in this department.
The AD131 outputs are still very easy to find replacements (are are compensated BE and E resistors to GND or center with ferite core coils to prevent oscillations) and the service manual shows a very good way to measure and match them to the specs, but the small shitty Ac151r matched pairs (wich can be found also in old tandbergs and uher) are trully almost impossible to find. It is full of them in this amp!!!! When the output burns out it will take the input stage of the amp Ac151 with them. Here you can use regular Ge parts to change. No fuss.
Let me tell you how to handle the scarcity of the originall siemens gems.
I happend to have RO/USSR made equivallents wich are abit more noisier and have extracted the originall ones from the stages more closer to the amp where the noise doesnt matter that much and replaced them with equiv parts without any noticeable difference and kept the originall low noise 2.5db genuine Ac for spare parts, so i can sleep well and happy listen.....
The originall Selenium bridge is usually in very good shape but crap by todays standars so i replaced it with a ultra fast soft recovery with extremely good results in soundstage, definition and channel separation.
Now for the phono i do think that the phono is very solid made but it has a inbetween RIAA and CCIR standar equalisation so that you can listen to them both (but actually it is not the best for each one of them so there it needs an improvement) and is abit unclear in presentation because of the Ge on the input. So a modification designed to low noise Si usage for the input and Ge on the second stage made things very good now. (thanks Dreamth) My opinion is that Ge is very good in phono but BAD for the first stage. It is astoundingly good at supressing clics and pops (just like valves) from my very old recordings wich amased me me!
And now the last part the main preamp wich has allot of very rare Ge wich is very very well build BUT isnt that incredible because of the loudness equalisation of that period in wich the sealed speakers have had a ton of hights and a very light bass and needed conpensation.. So this sucker in the 0 (12 oclock) is giving the amp a ton of bass and fewer hights so i unsoldered one of the terminal of the loudness equalisation chain and baaam the prob was solved..
In conclusion this is a very very good sleeper amp and to my ears Ge with output or phase splitter transformer or both are in the same league as the good class A out there.
So this amp needs a ton of love and care to make it blow you to smithereens so dont underestimate the Ge amps because there were good ones and bad cheap ones wich where bad sounding and unreliable because of the implementation.
In my opinion i would not make one from scratch because it will cost way more for the same quality so better refurbish a unit! I have buyed my amp one year ago at a price of only two new Alps blue velvet pots so just think about it.....
Bellow are pics with the amp finished and a couple of pics made after the upgrades.
I have buyed it very cheap but in an awfull condition and took two weeks to bring it here (change parts, thinkering, cleaning, and restained the wood) ... You may be luckyer than me....
Cheers
Attachments
Some more. The axials from the main pre are axial military tantal and the rest are nichicon and wima. You can see the cast zinc pots....
The big filtering caps are changed to 105 degree industrial type. The originall ones where ok but when i measured them i have allready buyed the replacement ones and opted for all new components.
The axial caps from the amp are siemens mkl, the blue ones are industrial 105dregree, green are muses and black nichicon kz and the litle ones panasonic fr... So as you can see that i tried to use as much quality parts as i can.
Cheers
The big filtering caps are changed to 105 degree industrial type. The originall ones where ok but when i measured them i have allready buyed the replacement ones and opted for all new components.
The axial caps from the amp are siemens mkl, the blue ones are industrial 105dregree, green are muses and black nichicon kz and the litle ones panasonic fr... So as you can see that i tried to use as much quality parts as i can.
Cheers
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@sergiu. Although I highly appreciate your enhusiasm I'd urge you to look at KLH 16 schematic before playing into the miracles of transformer coupled germanium amplifiers.You'll see a much different and maybe more interesting aproach to power germanium amplifiers.Here's a review for this amp:
https://www.stereophile.com/content/sound-transistors-klh-model-16-amplifierTransformer coupling with germanium was mainly done due to no real complement between pnp and npn transistors.Believe it or not making a high quality interstage transformer was a lot cheaper than finding suitable pnp and npn high power germanium transistors.Even the usual pairs of the industry , the ac 180-181/ac 187-188 transistors were significantly different in specs and i just finished measuring about 100 of them...In a higher power range than that the matching was virtually impossible on a production line if not impossible to source...Looking at the prices back then, best germanium amplifiers were priced almost equal or even more expensive than the best tube amplifiers in some cases...You can easily find a review for KLH 16 played on Tannoy Gold monitors so this amp was no joke.
https://www.stereophile.com/content/sound-transistors-klh-model-16-amplifierTransformer coupling with germanium was mainly done due to no real complement between pnp and npn transistors.Believe it or not making a high quality interstage transformer was a lot cheaper than finding suitable pnp and npn high power germanium transistors.Even the usual pairs of the industry , the ac 180-181/ac 187-188 transistors were significantly different in specs and i just finished measuring about 100 of them...In a higher power range than that the matching was virtually impossible on a production line if not impossible to source...Looking at the prices back then, best germanium amplifiers were priced almost equal or even more expensive than the best tube amplifiers in some cases...You can easily find a review for KLH 16 played on Tannoy Gold monitors so this amp was no joke.
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Hi Dreamth,
I was just reviewing the sv50, i am not enthusiastic; i was extremely enthusiastic when i found that it was directly comparable to a couple of class a designs . People dont know how it is and few how it sounds. I just love iron in my amp, be it autoformers, chokes, coils, trafos.
The klh is a very very interesting design. A very clever usage of the coils indeed. But till we find the klh here in RO we can find for shure a sv50 to get a taste of Ge. And I for shure dont have 100pcs of those transistors....
What a nice implementation has this klh and if im not mistaking i may have seen something similar in a pioneer vintage amp.
Cheers
I was just reviewing the sv50, i am not enthusiastic; i was extremely enthusiastic when i found that it was directly comparable to a couple of class a designs . People dont know how it is and few how it sounds. I just love iron in my amp, be it autoformers, chokes, coils, trafos.
The klh is a very very interesting design. A very clever usage of the coils indeed. But till we find the klh here in RO we can find for shure a sv50 to get a taste of Ge. And I for shure dont have 100pcs of those transistors....
What a nice implementation has this klh and if im not mistaking i may have seen something similar in a pioneer vintage amp.
Cheers
Attachments
Thanks Sergiu2009 for great post and photos sharing
Excellent Ge amp components update DIY work !! Congratulations!Cheers
@ Sergiu2009 & Diyers
Lucky to share not easy to find this days source of schematics by Hiraga etc.
You can download them from this French link
http://www.retronik.fr/revues/?dir=audiophile
The " Audiophile Integrale " in zip. format is highly recommended,
other versions year by year links on the page are OK.
Lucky to share not easy to find this days source of schematics by Hiraga etc.
You can download them from this French link
http://www.retronik.fr/revues/?dir=audiophileThe " Audiophile Integrale " in zip. format is highly recommended,
other versions year by year links on the page are OK.
My pleasure You can find much more articles, Ebooks on the home page
http://www.retronik.fr/
Thanks to Retronik.fr
For example
http://www.retronik.fr/Documentation-Thematique/Amplification_BF/Amplificateurs_a_transistors/Amplificateur_sans_transformateur_[RC199_1964_5p].pdf
http://www.retronik.fr/Documentatio...ateurs_BF_a_transistors_[Besson_1958_36p].pdf
+ http://www.retronik.fr/revues/
You can find much more articles, Ebooks on the home pagehttp://www.retronik.fr/
Thanks to Retronik.fr
For example
http://www.retronik.fr/Documentation-Thematique/Amplification_BF/Amplificateurs_a_transistors/Amplificateur_sans_transformateur_[RC199_1964_5p].pdf
http://www.retronik.fr/Documentatio...ateurs_BF_a_transistors_[Besson_1958_36p].pdf
+ http://www.retronik.fr/revues/
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Not sure how positive is this review. Do you really want an amp which is worse than an ST-70?
You might probably be the first I hear complaining about dynaco st-70...At the time they were listening those amps on high sensitivity speakers...It might have been a very different experience than what people today have with these amps.Never heard st 70 though...
The ST-70 is a classic tube amplifier. It has excellent output transformers, a decent power transformer, and an ancient power supply that needs to be replaced. The front end board also needs to be replaced. I like the version that uses a pair of EF86 small signal pentodes driven by an ECC99. Make these substitutions, install a fresh set of matched EL34 output tubes and you have an excellent amplifier.
Yeah, that is a lot of work but it can be a lot of fun. It is the amp that got me into DIY.
Yeah, that is a lot of work but it can be a lot of fun. It is the amp that got me into DIY.
These were the much sought cookbooks, and a rich source of stuff to learn. The golden era of documentation