Tube Amplifier and Tube pre-Amplifier Builds

Recently built a dual mono tube preamplifier with the PCB, I made few weeks ago. I used both imported and local made components. The transformers are from Precision, chennai. Soild state rectification and regulation for both HT and LT power supply. Although the preamp consume very less power the customers wants it to be dual mono design, so i made it. But really there is difference in the sound. it sounds very good.

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Now building a 40 + 40 Watts power amp. It is in fine tuning stage. It is the design published in EE magazine. Customer wants to control the amp through remote control, so added selector switch cum remote kit. Biasing the tubes and fine tuning are little bit tricky, but very interesting design.
i will update after completing the full work.

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Recently built a dual mono tube preamplifier with the PCB, I made few weeks ago. I used both imported and local made components. The transformers are from Precision, chennai. Soild state rectification and regulation for both HT and LT power supply. Although the preamp consume very less power the customers wants it to be dual mono design, so i made it. But really there is difference in the sound. it sounds very good.

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Very nice. Are these the ECC82 tubes ?
 
Can you tell me what’s the diff (if any ) in sound signature between same stock of ECC82 and ECC83 ?
Regarding sound I feel ECC82 or ECC81 tubes are more musical and sweeter than ECC83. The main electrical characteristics difference is its amplification factor, which makes it more popular and it is used in many powerfull amps. I feels it sounds clinical and slightly brighter in any circuit.
 
Regarding sound I feel ECC82 or ECC81 tubes are more musical and sweeter than ECC83. The main electrical characteristics difference is its amplification factor, which makes it more popular and it is used in many powerfull amps. I feels it sounds clinical and slightly brighter in any circuit.
Thanks for letting me know.
The ECC83 tubes are NOS ? And are they Mullard / BEL / Telefunken?
 
Thanks for letting me know.
The ECC83 tubes are NOS ? And are they Mullard / BEL / Telefunken?
I have few pairs of NOS 12AX7 tubes RCA, Telefunken (smooth plate), Mullard, Philips for testing purpose. For the customer due to budget limitations i use to give JJ, Tungsol reissue or Sovtek LPS 12AX7 tubes. The Sovtek LPS is one of the best new production tube.
 
Have you A-Bed yet, your DIY equipment using tie wraps, and then, the same piece with tie wraps removed, and the wires not touching each other?

drlowmu
 
Have you A-Bed yet, your DIY equipment using tie wraps, and then, the same piece with tie wraps removed, and the wires not touching each other?

drlowmu
Long time ago i did these types of experiments, i agree there will be some interference, disturbances in cables when they tied with each other., but not in all the cases. It depends on few other factors also like quality of cable, shielding, direction of flow signal or current, cold or hot side, etc., while tuning the ampIifier i check everything I wrap some cables which do not have any impact on quality of sound and i do not tie any cables which will affect the quality. I try to make my amp with clean layout as well as with high quality. Thanks for checking my post. Your SE 6005 DC amp thread is very interesting i regularly watch your updates, all the information you post is very usefull. Thank you.
 
Nice effort on your part !! Can I make a couple of suggestions, for you to consider, without people getting upset with what I say ??

1) Keep the 230 VAC line INPUT as far away as possible, from the speaker output jacks. That amp's 230 VAC entry, and fields around the AC ON-OFF switch, is mis-positioned as shown.

2) Use a 20 A. IEC. system, not 15 Ampere.

3) Learn to execute Push Pull amps in two, not three stages. Less stages is better, the middle stage always loses information.

4) Build direct coupled amplifiers, eliminate the series coupling cap. two runs of lightly twisted pure silver wire, connecting two stages, is superior in it's performance.

5) It would be better, performance -wise, to position the RCA inputs, close to the grid of the Input tube, ie : two inches or so - and at the front of the amp.

6) Any volume pot, on the input of the amp, should always be optional, with a separate set of RCA jacks available to the user, to go direct in. A volume pot on the input degrades the input signal, and the input signal is the lowest level of signal the circuit " sees" in the amp, subject to easiest degrade.


Master Schematic 4 SNIP explained.jpg
 
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When using multiple power transformers, such as shown in the photo below, it is of utmost importance to be sure that all leads are connected in proper relative phase to each other. This applies first to the primary and then, to the secondary AC lead orientations, equally..

Use any simple O-scope, to see that the phase trace of each and every primary and secondary winding is in synch. For example, notice in the photo below, the two blue wires coming off the R-Core secondary, and connected to adjoining boards. The Blue-Blue wires denotes leads off a single winding. However, there is no denotation from Blue-Blue, of what is in or out of AC waveform phase, one power transformer, relative to another, or to that single transformer's primary winding..

This can lead to a dual mono design such as this one, sounding worse than a single power transformer, because of AC phases bucking each other, channel to channel.

Phase determinations can be made, if careful, by A-B ing the sound by ear. I have done this . A far easier and more foolproof way is to use a scope, and observe the sine wave directions.

To that end, I have dusted off my TEKTRONIX scope, variaced it up after a many years non-use, and will use it as suggested herein. I use lots of multiple power transformers. The overall audible difference, between correct and incorrect phase or every AC winding, ( the sum total of all windings when orientated correctly ), is rather large in my recent listening experiences.

Do not ignore this, you have a 50-50 chance of the AC phase being wrong or right, for each winding, when connected unconsciously !! Apply proper care, and start with the primaries' orientations first . !!

I am of the belief, that this outlined and important-to-the-final-result procedure is totally overlooked, by the vast majority of audio industry manufacturers, and amateur DIYers.

Phasing Multiple XFRs.JPG

Thanks for reading this !! Share with us all, your resultant listening experiences.

drlowmu
 
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Now building a 40 + 40 Watts power amp. It is in fine tuning stage. It is the design published in EE magazine. Customer wants to control the amp through remote control, so added selector switch cum remote kit. Biasing the tubes and fine tuning are little bit tricky, but very interesting design.
i will update after completing the full work.

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The books look familiar! Felling sleepy already! :)

Are you a Mech Engineer?
 
It depends on few other factors also like quality of cable, shielding, direction of flow signal or current, cold or hot side, etc., while tuning the ampIifier i check everything I wrap some cables which do not have any impact on quality of sound and i do not tie any cables which will affect the quality.

Hello @radium7,

What is your preferred choice for power and signal cables in your builds?

Thanks.
 
I just noticed today, that you were using dual mono r-core power transformers in your preamp, which were built by Precision Transformers, in Chennai. I am using Shilchar Technologies, this very moment to build six custom 320 VA R-Cores.

However, I am looking for alternative sources, that are easy to deal with, for additional R-Core XFRs.

As an example, I need some 120 VAC to 5.1 VCT @ 3A. r- cores, on 30 VA cores, 2% or better tolerance. ( These will be used to power tube rectifier filaments, 5U4Gs, etc. )

When I tried to contact Precision Transformers in Chennai today, I get a messsage on line, that their business is permanently closed. To your knowledge, is that information correct ?? Thanks in advance, from you, or anyone else, for any help on this subject .

Jeff in the USA.

Permanently CLOSED.JPG
 
I just noticed today, that you were using dual mono r-core power transformers in your preamp, which were built by Precision Transformers, in Chennai. I am using Shilchar Technologies, this very moment to build six custom 320 VA R-Cores.

However, I am looking for alternative sources, that are easy to deal with, for additional R-Core XFRs.

As an example, I need some 120 VAC to 5.1 VCT @ 3A. r- cores, on 30 VA cores, 2% or better tolerance. ( These will be used to power tube rectifier filaments, 5U4Gs, etc. )

When I tried to contact Precision Transformers in Chennai today, I get a messsage on line, that their business is permanently closed. To your knowledge, is that information correct ?? Thanks in advance, from you, or anyone else, for any help on this subject .

Jeff in the USA.

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It looks like they have shifted office location. You can try contacting them on whatsapp.9962848027
 
I just noticed today, that you were using dual mono r-core power transformers in your preamp, which were built by Precision Transformers, in Chennai. I am using Shilchar Technologies, this very moment to build six custom 320 VA R-Cores.

However, I am looking for alternative sources, that are easy to deal with, for additional R-Core XFRs.

As an example, I need some 120 VAC to 5.1 VCT @ 3A. r- cores, on 30 VA cores, 2% or better tolerance. ( These will be used to power tube rectifier filaments, 5U4Gs, etc. )

When I tried to contact Precision Transformers in Chennai today, I get a messsage on line, that their business is permanently closed. To your knowledge, is that information correct ?? Thanks in advance, from you, or anyone else, for any help on this subject .

Jeff in the USA.

View attachment 58531
They shifted to new location and they are functioning now. You can contact them in these no: 9962848027, 9444205164.
 
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