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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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27th Feb 2012, 6:18 pm | #61 |
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Re: My first experience with electronic tubes
I don't think I've encountered that arrangement before. It's very unusual, but it should work if you ensure that everything is phased correctly.
I don't think there is any need to use isolating rubber mounts if this amplifier is intended for a normal domestic environment, but it will do no harm to experiment |
27th Feb 2012, 6:35 pm | #62 |
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Re: My first experience with electronic tubes
Yes, it works.
If it's connected in counter-phase, the output will be zero or very, very small. Now I'm analizing how to feedback it. I thought in rubber washers to avoid microphonic effect in the valves due to main transformer vibrations.
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27th Feb 2012, 6:42 pm | #63 |
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Re: My first experience with electronic tubes
Microphony should not be a problem at these signal levels. It would be much more significant in a preamplifier connected to a microphone, record player cartridge or tape head.
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6th Mar 2012, 4:20 pm | #64 |
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Re: My first experience with electronic tubes
I have just noticed that two of my three 6P14P are not really 6P14P but EL84 TESLA. They are fine, and I have always preferred TESLA over the Soviet components. Looking the pictures of my "homebrew temporary amplifier" you will notice the diferences.
Soviet valves ussually have a dish for the getter while other valves including TESLA have a ring. Saddly TESLA valves get their marking deleted very easily, as is the case with two of my pentodes. They were retrieved from the audio socket of Soviet TVs, so I thought they were 6P14P. Maybe this two pictures (downloaded from Internet) can explain better what I'm saying about the diferences http://www.tubemongerlib.com/gallery...ov+-+Czech.jpg TESLA EL84 http://www.parts-recycling.com/Metal...-nos-photo.jpg Soviet 6P14P
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7th Mar 2012, 10:59 am | #65 |
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Re: My first experience with electronic tubes
Your amplifier is looking good Miguel. The way you've configured your OPT's as Paul says is unusual; clever stuff. I think youve done wonders for saying this is your first valve project and have limited resouces.
Andy.
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7th Mar 2012, 3:53 pm | #66 |
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Re: My first experience with electronic tubes
Thank you Andy, I do my best.
I've been thinking to switch between a 6N2P (ECC83) and a 6N1P (E88CC) to obtain different frequency response. I like the 6N1P (nice flat response), but the 6N2P has wonderful (and powerful) bass. I have not decided anything regarding this....any opinion? The problem is that the one that is not been used will be consuming power for free, and spending lifetime too BTW, a jobmate gave me another 6P14P, Soviet for sure, retrieved from an old TV Krim-218 he had abandoned in a corner. If it is not rainning, I will finish the chassis and the cabinet this weekend.
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When electrons move, things happen. There's nothing you can do that can't be done. Last edited by Miguel Lopez; 7th Mar 2012 at 3:59 pm. |
7th Mar 2012, 5:08 pm | #67 | |
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Re: My first experience with electronic tubes
Quote:
The E88CC is a special quality version of an ECC88 and was designed for high speed switching in 1950s valve computers and laboratory equipment. It will certainly work, but won't sound any different. The ECC83 is an audio double triode designed for this application. I'm not familiar with your Russian equivalents though. |
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7th Mar 2012, 5:20 pm | #68 | |
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Re: My first experience with electronic tubes
Quote:
6H1P, as said, I feel same amplification for the entire band, good bass, good treble. 6H2P, powerful bass (when I say powerful I mean really POWERFUL), and acceptable treble. If valves swapping has no effect my ears are wrong. I can not explain why. Thought you could help me.
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7th Mar 2012, 5:52 pm | #69 |
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Re: My first experience with electronic tubes
The ECC83 has a higher amplification factor than the ECC88, so it may sound louder. This may mislead you into thinking that the frequency response has changed.
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7th Mar 2012, 5:59 pm | #70 |
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Re: My first experience with electronic tubes
Good point Paul. That is what is possibly hapenning. I have not checked what is the volume level in each case to obtain same power in the speakers, I'll check it out.
After answer you, I thought that if I want to change the frequency response, I only need to switch ON/OFF the C7 capacitor (not shown in my scan, but in the opening post pic http://promka.at.ua/Statti/UMZCh/Lampa/10Vt.jpg). C7 is present in my "amplifying thing" mounting (can't call it amplifier yet) With C7 it will have more bass and less treble, without C7, trebles will improve. What do you think?
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7th Mar 2012, 6:06 pm | #71 |
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Re: My first experience with electronic tubes
C7 will cause the frequency response to roll off. It doesn't affect the bass response directly. A bigger value will mean less treble, and a smaller value (or complete removal) will mean more treble. Feel free to experiment
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7th Mar 2012, 7:07 pm | #72 |
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Re: My first experience with electronic tubes
I wouldn't bother with fixed component changes for frequency response, a Baxandall tone control would only take one half of a double triode or a whole one for stereo.
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7th Mar 2012, 7:13 pm | #73 |
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Re: My first experience with electronic tubes
Yep, but that requires a couple of tandem pots, or four identical independent pots. I don't have them.
Well, independent pots I should have several of them, but Soviet pots are............I can not say that word here.
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8th Mar 2012, 12:07 pm | #74 |
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Re: My first experience with electronic tubes
The ECC83 has greater gain. You appear to have a negative feedback loop. More gain could push you nearer oscillation at frequency extremes where phase shift increases. The 'more bass' you hear could be a bass peak due to being on the edge of LF instability.
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23rd Mar 2012, 5:53 pm | #75 |
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Re: My first experience with electronic tubes
It took me some time but finally I could take some pictures of what I have done till now. Any comment welcomed.
I have not wire any part. They are just presented to show how it will look when I finish it (more or less)
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25th Mar 2012, 12:08 am | #76 |
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Re: My first experience with electronic tubes
I'm impressed with your chassis work there.
Jay
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30th Mar 2012, 6:45 pm | #77 |
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Re: My first experience with electronic tubes
Beginning to mount components
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9th Apr 2012, 1:34 pm | #78 |
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Re: My first experience with electronic tubes
Some pictures of the amplifier cabinet and wiring. It is a little mess but I promise to make next one more tidy.
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9th Apr 2012, 4:04 pm | #79 |
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Re: My first experience with electronic tubes
That looks absolutely fine Miguel, you also have some nice looking "C" core transformers in there, were they ex military? This type of transformer is good but expensive,.
Ed |
9th Apr 2012, 5:17 pm | #80 |
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Re: My first experience with electronic tubes
"C" core transformer were the ussual core type in Soviet consumer electronics in the 70s and early 80s. Those in the pictures were retrieved from Krim-218 B/W TV-sets. They are TC-180 mains transformer, and TBK-110 vertical output transformer.
Military electronics also used those type of cores, but I don't have any right now. I used one in the first soldering gun that I made.
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