My Fairchilds were hopeless too, in the same way, and i bought it from RS.
Then i bought one more batch Diotec brand from Conrad in Germany, and it was much better matched.
Then i bought one more batch Diotec brand from Conrad in Germany, and it was much better matched.
In the Mpp thread I have posted this http://www.diyaudio.com/forums/analogue-source/154210-mpp-774.html#post3252128 about grounding and connecting the player to the preamp.
As announced in the group buy thread: All parcels are out the door. So I would like to ask all builders to share their insights, experience and of course listening impression !!!
With 300 essentially identical phono stages to be built around the world, this could be a great source of insight into many things, like cartridge - preamp interaction, component choice, arrangement in the case, etc etc - Looking forward to all the sharing! And of course, in case of issues or problems just post here and I am sure the team will be happy to support.
However, we all want this thing to work at first turn-on, so please read the assembly guide carefully , there is a lot of experience from the beta builders already there.
Please note: There are various references floating around, to R2 and R3 - both are the same except the input offset trimming which is implemented in the R3, so no worries.
Happy building!
With 300 essentially identical phono stages to be built around the world, this could be a great source of insight into many things, like cartridge - preamp interaction, component choice, arrangement in the case, etc etc - Looking forward to all the sharing! And of course, in case of issues or problems just post here and I am sure the team will be happy to support.
However, we all want this thing to work at first turn-on, so please read the assembly guide carefully , there is a lot of experience from the beta builders already there.
Please note: There are various references floating around, to R2 and R3 - both are the same except the input offset trimming which is implemented in the R3, so no worries.
Happy building!
Where are the matched transistors located? Are they just the 8 spots in brackets flanked by the 6800 caps?
On matching
I tried litle (big) Atals unit and mesure low
Tried curve tracer (but don't trust it) and Example get 563
Tried circuit published on build guide and mesure example 555
Litle circuit there is prety good.....
I tried litle (big) Atals unit and mesure low
Tried curve tracer (but don't trust it) and Example get 563
Tried circuit published on build guide and mesure example 555
Litle circuit there is prety good.....
The answer to your question is on the first page of the assembly guide. The most important match is the 8 transistors at the input gain stage (these should also have the highest HFE). It's also important to match the transistors in each current mirror. But not necessarilly one mirror to the other, although I'm sure that won't hurt.
Mark
Just dont say it out loud, that it isnt Vishay. If the RIAA doesnt know, it will probably work anyway.😀
Got a S...T load of BC327-40 Original Fairchild with HFE hiegher than 540
This mesured with "litle big circuit" at 5 V 20 C
Same go up to the 600 and wuld like to swap for same Hi (hef more than 550) BC337
Also If you stuck give us a PM
This mesured with "litle big circuit" at 5 V 20 C
Same go up to the 600 and wuld like to swap for same Hi (hef more than 550) BC337
Also If you stuck give us a PM
I got few PM about the transistors.
Same questions would be helpful to general population so I am going to post replies here
1 1to help
2to live replies open to constructive comments, as I don't know much
3 I am going to use spel cek in public😀
Up to you if one decide to make intelligent questions useful for everybody
Before we start
Group buy for components was really big help (I subscribed to it as well); one can build paradise with those no problems and be really happy whit it (be prepared to ditch old TT and Cart as R2 version that I am listening at present as beta builder is pretty good)
So I am in no way saying that one can't do it with what is supplied all I am saying is that maybe if you got time (loads of it and easy as I have paradise R2 up and running ) and same cash there are options to make things a little bit better.
Q: wuld you match just the transistors how
I am going to match the Jfets as well
Paradise is ok without to much fussing about but if you can match it will be better
For matching use the 5 volt circuit as published and match groups as in the build guide.
Mouser sells BC327-40 BC337-40 for £22 for 500 0r £30 for 1000
How many you get depends on your pockets, if you could find same friends to share be better.
If you can get them on ammo pack (Taped together) you are more likely to have closer Hfe match
Then once you got them if you are lucky you get hi Hfe as specification say Hfe between 250 and 630 for the 40 type.
All the best
Sandro
Ps Your question could be useful to all if ok with you why not post on forum?
Same questions would be helpful to general population so I am going to post replies here
1 1to help
2to live replies open to constructive comments, as I don't know much
3 I am going to use spel cek in public😀
Up to you if one decide to make intelligent questions useful for everybody
Before we start
Group buy for components was really big help (I subscribed to it as well); one can build paradise with those no problems and be really happy whit it (be prepared to ditch old TT and Cart as R2 version that I am listening at present as beta builder is pretty good)
So I am in no way saying that one can't do it with what is supplied all I am saying is that maybe if you got time (loads of it and easy as I have paradise R2 up and running ) and same cash there are options to make things a little bit better.
Q: wuld you match just the transistors how
I am going to match the Jfets as well
Paradise is ok without to much fussing about but if you can match it will be better
For matching use the 5 volt circuit as published and match groups as in the build guide.
Mouser sells BC327-40 BC337-40 for £22 for 500 0r £30 for 1000
How many you get depends on your pockets, if you could find same friends to share be better.
If you can get them on ammo pack (Taped together) you are more likely to have closer Hfe match
Then once you got them if you are lucky you get hi Hfe as specification say Hfe between 250 and 630 for the 40 type.
All the best
Sandro
Ps Your question could be useful to all if ok with you why not post on forum?
As i had the chance to talk to Joachim about this issue,
i learned it is not usefull to spill the highest hfe all over the place.
As far i can remember the highest 8 with good match have to go
to the straight line right before the RIAA.
But whitch values to the other bunches ?
And how low should or can they go ?
Another issue that keeps me awake is how and with what material
the obvious shielding has to be done...