Green, G9 and slowblow mic pre.

[FotisGR]

Having finished a year ago the green mic pre, i started to build a tube mic pre. I was between G9 and Slowblow. A couple of times a asked on this forum for people that builded both of them for comparisons but i wasn't lucky.
Yesterday i finished G9 and i was very very happy. But i was always wondering for Slowblw pre because i like its simplicity. Nothing personal, i just like the srpp topology.
So, the afternoon i took a spare board and build the slowblow. Nothing special. It was ok the next 30 minutes :grin: . Point to point construction, and everything on the air . pcb used only for base and ground connections. Cheep spare caps and tube sockets. Cheep and low quality electrolytics.

G9 constructed with high quality components, like Blackgate electrolytics, Solen PB and Hovland caps and good quality cearamic tube sockets.

Both of them has OEP trafos and the same Philips tubes, except the 5687wb that was GE. For powering Slowblow i used the G9's psu. Only for HV i take it via a resistor from 783's input voltage (335V).
I visited 2 friends for coffe and after 1 hour warm up the pres we begin...
I forget to say tha the mic was a TLM103. The programm was only a girl that sing and speak like heaven.

All of us said the same like one voice. G9 sounds like semiconductor and Slowblow like a highest-end tube. Sayind tube i don't mean fat vintage sound. Slowblow sounds like heaven . G9 is little overall dirty with thin and tiny highs. G9 sounds a little bit thin and dirty comparable with slowblow that is fullness with the deepesat and clearest low end that i ever heard. But the differencies are not on low end. Slowblow is a really highest end mic pre. Mellow, fullness, crystal clear highs. We couldn't beleive that TLM103 will be so perfect, ever...
After another cup of coffe i put the green on the game. My green i bulded with high quality components. Blackgate and Solen caps, even on PSU. (Sorry about it , but... i like these components).
The green is wonderfull mic pre . Nice sounding. It's more on the side of Slowblow. Like a poor Slowblow. If i put a number, green is on 60% , G9 on 70% and Slowblow maybe more than !00%.

Finally i want to Give my greetins to Jakob, Slowblow, Peter and all the group that share them with us.

I love DIY spirit.
Cheers
Fotis

 

[dufo]

Thanks for the interesting comparison.

Im quite surprised the G9 didnt hold up that well.

Im interested in looking at the slowblow, can you point me in the direction of the schem./info? thanks

 

[gyraf]

Im quite surprised the G9 didnt hold up that well.

..that is very much a matter of taste and application.. :razz:

Jakob E.

 

[dufo]

[quote author="gyraf"]

Im quite surprised the G9 didnt hold up that well.

..that is very much a matter of taste and application.. :razz:

Jakob E.[/quote]


oh absolutely!!

It just reads to me as if it got blown away by the slowblow, whatever that thing actually is. :grin:

Anyway, couldnt be happier with my G9. :grin:

Im interested in learning more about the slowblow though, learning a different topology would be educational for me.

 

[MrZpliff]

I'm also 100 % happy with my G9. I think it sounds very, very good !
It killed my former TLAudio Ivory pre (which I've now sold)

I must say FotisGR got me curious, I will definetly chek the slowblow out :green:

 

[robomatique]

Slowblow? ANy schematics or info?

 

[FotisGR]

:sad: Sorry but i didn't wrote my opinion to make sad or happy anyone...
Just my opinion. I build both of them so i have an opinion about only for diy spirit, not for anything else. I don't sale anything, i just like to diy. The better way is to build a slowblow pre (no more than 30 minutes ) and give it a try...
48v and 12v from G9 psu normal outs and high voltage (320V) from the juction R33,C14 via a 1k/2W resistor. So simple, putting two tube bases on a piece of metal and no more than 10 components.
Maybe you will be surprised.
It is truth that G9 is very very nice but slowblow is like the sea, giant.
It is truth, too, that at high-end levels, there are "taste" differencies no basic quality differencies. But sorry slowblow is something on highest-end.
G9 comparable with slowblow is like the mic cable to G9 is 1000ft away...

Slowblow? ANy schematics or info?

http://www.wwnet.net/~dhicks/misc/stuff.html

Thank you again friends for your diy spirit :thumb:
Cheers
fotis

 

[MrZpliff]

Thanks for the tip, FotisGR :razz:

I have two input trafos from an old Soundtracs mixer lying around so
I think I'll start building it right away... it really look simple (even for a newbie like me)

Magnus

www.bitterend.se

 

[clintrubber]

I understood there's not really a Eu-replacement for the 5687 - or will a ECC88 do just fine in this design ?

 

[chrissugar]

Interesting thing is, probably many of the new members don't know, that Jakob at the old place (years ago) explained us the evolution of the G9 design.
If I remember corectly, Jakob said that before the curent G9 version he had a similar dual SRPP preamp but that had some headroom problems, so he opted for this design. So it is hard to believe this version is not as good as the dual SRPP. I think it is probably just different.

chrissugar

 

[dufo]

[quote author="FotisGR"]:sad: Sorry but i didn't wrote my opinion to make sad or happy anyone...
Just my opinion. I build both of them so i have an opinion about only for diy spirit, not for anything else. I don't sale anything, i just like to diy. The better way is to build a slowblow pre (no more than 30 minutes ) and give it a try...
48v and 12v from G9 psu normal outs and high voltage (320V) from the juction R33,C14 via a 1k/2W resistor. So simple, putting two tube bases on a piece of metal and no more than 10 components.
Maybe you will be surprised.
It is truth that G9 is very very nice but slowblow is like the sea, giant.
It is truth, too, that at high-end levels, there are "taste" differencies no basic quality differencies. But sorry slowblow is something on highest-end.
G9 comparable with slowblow is like the mic cable to G9 is 1000ft away...

Slowblow? ANy schematics or info?

http://www.wwnet.net/~dhicks/misc/stuff.html

Thank you again friends for your diy spirit :thumb:
Cheers
fotis[/quote]


ahh no, not sad, its all good!! Im interested in the comparisons .


Seems alot more than 10 componenets tho , going off the parts list. Unless im missing something...

 

[Jazzy_Pidjay]

Fotis, can you share some short comparison samples ?

i think many people here like to ear the slowblow sea sound !!

:thumb:

 

[sismofyt]

eta 100706

new link:

http://www.sismofyt.net/slowblow.html

 

[laitue5]

[quote author="sismofyt"]

[/quote]
For the moment you seem to be? busy? :thumb:

 

[FotisGR]

Yes, it's true, SlowBlow is a real killer on everything. I built mine with Lundahl at i/p and o/p and I hope you get the picture what it's like compared to an OEP input. To put it short: It's an orgasm machine!

Orgasm mashine :grin: All that i tried to explain with 2 words :thumb: .
Today i ordered 2 Lundahl trafos. I wish i have them this weekend.
If i save a bit of time this week i will try to bias the heater to HV supply and maybe a much better supply to hear the differencies. The supply i used for slowblow has only an RC from 1k and 200uf summary. You know, less than 30 minutes construction... :razz:

Cheers
fotis

 

[sismofyt]

hello kubi. the srpp pre was designed to be very dynamic and transparant. and easy to diy. i've tried similar gainreduction schemes like the G9, but i've never been happy with that kinda feedback. that's the biggest difference between the slowblow and the G9. that, and the PSU and output trannie. i think 4:1 output trannies and similar messes up the sound too much, so i avoid them.

i find it more pleasing to dick around with tubes than trannies anyway.

next projects:

WE417A & GE12B4A, two tubes, one Jørgen Schou input trannie, seven components and a EZ81 CLCLCRCRC PSU. total killer. everything sounds better coming out of that one.

RCA2C22, SYL1629 & RCA6AS7G, Peerless 4722, 500VDC and controlable distortion. wicked.

 

[sismofyt]

the heaters must be biased some 50-60VDC above ground if you don't want to change tubes too often. also helps with the humlevel (in general).

 

[FotisGR]

the heaters must be biased some 50-60VDC above ground if you don't want to change tubes too often. also helps with the humlevel (in general).

I was thinking about 100-120V. The prototype has a litle hum but the construction wasn't good and the HV reg not enough.
By the way what is the usage of this trick ? ( i have not good knowledge with tubes). Any sound effect about it?

Cheers
fotis

 

[dufo]

[quote author="sismofyt"]hello kubi. the srpp pre was designed to be very dynamic and transparant. and easy to diy. i've tried similar gainreduction schemes like the G9, but i've never been happy with that kinda feedback. that's the biggest difference between the slowblow and the G9. that, and the PSU and output trannie. i think 4:1 output trannies and similar messes up the sound too much, so i avoid them.

i find it more pleasing to dick around with tubes than trannies anyway.

next projects:

WE417A & GE12B4A, two tubes, one Jørgen Schou input trannie, seven components and a EZ81 CLCLCRCRC PSU. total killer. everything sounds better coming out of that one.

RCA2C22, SYL1629 & RCA6AS7G, Peerless 4722, 500VDC and controlable distortion. wicked.[/quote]

GAINreduction ??? :shock:

 

[NewYorkDave]

He means negative feedback, I'm sure. One of the effects of negative feedback is indeed gain reduction. (Or "gainreduction"... I love how the Europeans make compound words out of everything :wink.

The main purposes of negative feedback are to reduce distortion and to achieve a predictable amount of gain. The G9 uses plate-to-cathode feedback wrapped around two common-cathode stages. One of my own preamps [schematic] does also, in a simpler arrangement than the G9 (which might be easier to understand when you look at it).