Sujet DIY : Ampex 351 ?
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barnee
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C'est juste une question...
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Anonyme
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Cela dépend de la dispo des schémas, des PCBs, des composants...
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barnee
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tiré d'ici :
http://www.electrical.com/phpBB2/viewtopic.php?t=498
Le forum du studio de Steve Albini...
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Citation :
Here is a list of corrections to the schematic-
R55- is 6.8k instead of 1.5k
R58- is a 20k instead of 15k
R49- does exhist and it should be replaced with a 39k resistor (this resistor is in between pin 3 of V4 and Red/Yel connection on the middle board.
No tubes use the 12.6V AC for their filaments. They only use the 12.6 V DC.
The attenuator is not a Davin but a Daven.
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Citation :
Copy down all the component values (on the schematic) and order new parts. For all the electrolytic caps use 105 degree rated caps for replacement (Sprague, Panasonic TS series are good). Don't change the uF value, round higher on the voltage rating. For the resistors, get 1% 1/2 watt metal film ones. We used Rel-Cap polypropylene film caps for the interstage DC blocking caps (C1,18,21,19 etc.) C20 is a polystyrene film cap, the .47uF cap bypassing the 10uF cap on the B+ is polypropylene, and C4 is an orange drop cap.
The Daven o/p attenuator is not an off-the-shelf item anymore. What you need to get is a o/p attenuator that will have an input and output impedance of 600 Ohms through its rotation. You might be able to find this at a hi fi audio builder site.
We are in the process of replacing the gain pot with a 12 or 16 position switch for better tracking of gain per degrees of turn. Otherwise just get a nice Clarostat pot for the main gain.
I have been replacing the selenium rectifier (for the 12 DC power supply) with a bridge rectifier, because they have caused problems in the past.
We added jumpers when needed to bring signals and voltage to specific spots on the boards. If you get a cap that needs a bigger pad/hole to attach to don't be afraid of hacking a bit. If you are committing to this, be only concerned with making it a preamp. It most likely will not be converted back to being a part of a tape machine.
Take care and not burn the traces of the board when stripping them. Removing the Tube sockets will be the worst part. Keep good track of the wires, where they plug in to the board, and what direction the plugs are facing. I shocked Soren (old tech) once when I had the plugs reversed. I recomend getting a solder sucker ($10 at radio shack), solder braid, and screwdriver shaped tip for your iron. I like to have the heat high (if you have a soldering iron with that kind of control) and desolder fast. Practice on a part of the board that isn't going to be reused.
You're going to constantly have to retrace you're steps making sure things are where they should be. It is a simple cicuit to follow, but a mess in the box.
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Anonyme
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l'électronique ne me semble pas très compliquée (quoique je n'ai aucune idée sur la dispo des tubes 6198). Le plus gros problème dans ce préamp est de trouver les transformateurs. D'une part le transformateur de puissance n'est pas commun. D'autre part, le transformateur T3 n'est pas lui aussi courant, et probablement qu'ils sont dédiés à ce montage...
Si tu souhaite faire un préamp à lampe, il y a :
- le G9 dont la commande groupée arrive à terme (Neya collecte les chèques actuellement). Si tu est preneur : dépêche toi !!!
- le slowBlow réalisé par Jazzy Pidjay
D'après Jazzy Pidjay, les deux préamp sont très différents...
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Anonyme
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Ampex 351 Line Output. 15K/600 +NFB 80 Euro,
et ça :
Ampex 351 Input 200/50kohms 80 Euro !
Pour l'alim, peut être que les pros des tubes peuvent proposer une solution de remplacement...
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webowood
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transfo de sortie autre source, cinemag CM-9600-T http://cinemag.biz/application_notes/AN-106.pdf
transfo de puissance
https://www.tube-town.net/ttstore/index.php/cat/c79_TT--Torodial-Transformers.html/XTCsid/e1d00fb2c444cafece279323749c822f
néanmoins le 351 n'a pas un son d'anthologie, enfin les gouts et les couleurs
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