The amplifier has been from 1954 to 1989, when it came out, except that the operation, the average activity for 15 hours a day. It is not present in damages in excess, in particular the replacement of the tubes, capacitors and resistors, caused by natural wear. The fundamental change came with the replacement of a provision of the tube, to restore diodes. There is only one problem, they try to produce the transformer cost, (it is valid for all pipe manufactured), one of the code is there and it will help. It may cost to replace traditional transformer suitable for EL34. Its products they need (it is the force responsible for all districts), sufficient experience and attention to the high voltage electric shock.
For this project, I decided to use some of the EL34. Check out DrTube [0] for additional information. Offer good performance at a decent price.
The load of reflection allows KT88 instead of one, if not provided enought power.
For the pre, I think I’m going to use a 6SN7 in SRRP. These offer a good profit, and very good linearity.
Output transformer
EL34 has a load of reflection 2kohm, I found coresponding processors. Obviously a lot of money, Hammond Cost HiFi (not guitar), output transformer for 20W costs about $ 99 each. And
Even worse, I can not be found, only 2.5 per 2.0k flows.
Power Supply
This part is not really clear to me now. Located Ended amplifiers should not be regulated PSU, because in pure class A job, for which the current is fixed (thought the tube bias), but they really want to avoid distortion.I stable, do not buy a transformer large because it costs much money and not my feet with my needs. EL34 use a very low voltage (~ 250V), but are largely in progress ~ 100mA. I think a good isolation transformer can do the job. Something like 230 * 230 to 200VA does not cost much money.
35w tube amplifier
Electronic Parts
R1=470K 0,5W
R13-21=820K 0.5W
R12-23= 180K 0.5W
R2-5= 2K2 0.5W
R14-22=5K6 0.5W
R3=150K 0.5W
R15-20= 680K 0.5W
R4= 220K 0.5W
R16-19=100K 0.5W
R6-10= 56K 0.5W
R17-18=3K3 1W
R7=3.9K 0.5W
R24=470R 2W
R8= 220R 0.5W
R9= 1M 0.5W
R11= 39K 1W
C2=220pF 600v
C8-9=0.1uF 630V
C10-14=0.47uF 630V
C4-5=16uF 550V
C11-13=25uF 40V
C1-3-6-7=0.1uf 630V
V1=E80CC
V2=E80CC
V3-4=EL34
TR1-2=470R 1W Variable (adj. 270?) Rectifier
tube= Z2C
T1=Audio Transformer for 2x EL34 Push Pull
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