So I think I may have jumped in to purchasing some components a little quick and I'm not 100% sure what to build yet.
I have no experience building audio equipment and don't own any either... but I REALLY want to get into it and purchased the following:
(2x) Gold Lion KT88
(2x) Sovtek 5751
(1x) EDCOR CXPP25-MS-8K
(1x) EDCOR XPWR105-120
I was planning on building: THIS PROJECT and I still may... just looking for some input.
Then, I was looking at THIS PROJECT but I would have purchased the wrong Iron, I believe (forgive me.. I am even new to circuits in general)
So what I am looking for is some confirmation that I should build the first project that I originally purchased the parts for or if there is a more simple project to start with that would perhaps sound as good (or better).
Thank you for any suggestion!
Im sure I'll come back with some more questions when I confirm which project to do...
Here is a rendering I did just getting excited:
I have no experience building audio equipment and don't own any either... but I REALLY want to get into it and purchased the following:
(2x) Gold Lion KT88
(2x) Sovtek 5751
(1x) EDCOR CXPP25-MS-8K
(1x) EDCOR XPWR105-120
I was planning on building: THIS PROJECT and I still may... just looking for some input.
Then, I was looking at THIS PROJECT but I would have purchased the wrong Iron, I believe (forgive me.. I am even new to circuits in general)
So what I am looking for is some confirmation that I should build the first project that I originally purchased the parts for or if there is a more simple project to start with that would perhaps sound as good (or better).
Thank you for any suggestion!
Im sure I'll come back with some more questions when I confirm which project to do...
Here is a rendering I did just getting excited:
Did you by chance mean this amp using the 5751 as the driver?
OddWatt Audio 5751 SRPP / KT88 Push-Pull Monoblock Tube Amplifier Kits
If so, that would make a nice amp but it is a mono-block. The title of your post says "stereo". If your intention is to build two mono-blocks, you will need 2 more KT88, 1 more output transformer, 1 more power transformer.
edit: my mistake, the 5751 or 12SL7 can be used interchangeably, with the exception of the heater voltage.
edit 2: the KT88 require 1.6A heater current. The Edcor you have specified can only provide 6.3V at 3A. I believe you will need a different transformer or auxiliary heater supply.
OddWatt Audio 5751 SRPP / KT88 Push-Pull Monoblock Tube Amplifier Kits
If so, that would make a nice amp but it is a mono-block. The title of your post says "stereo". If your intention is to build two mono-blocks, you will need 2 more KT88, 1 more output transformer, 1 more power transformer.
edit: my mistake, the 5751 or 12SL7 can be used interchangeably, with the exception of the heater voltage.
edit 2: the KT88 require 1.6A heater current. The Edcor you have specified can only provide 6.3V at 3A. I believe you will need a different transformer or auxiliary heater supply.
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The schematic in MY FIRST CHOICE shows KT88s with (1x) EDCOR CXPP25-MS-8K
and (1x) EDCOR XPWR105-120.
Is that incorrect? Will that not work?
and (1x) EDCOR XPWR105-120.
Is that incorrect? Will that not work?
Maybe I'm confused, but the transformer he has will only supply 3A at 6.3VDC. The KT88s are 1.6A each. The transformer spec'd for the 5751 version is 6.3VAC at 4A. I did not see a SMPS in the bill of materials. The addition of the SMPS for the KT88s would do it. The 5751s can run from the transformer that is specified.
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I understand, although it is not listed in the BOM. I suppose that's where I made the assumption and resulting mistake in my post.
Have you already got the parts from Edcor or have you just ordered them? I understand there is some lead time from order, so you might be able to change the order to something more appropriate when you have decided on a design. The Edcor site is down at the moment, but the output transformer looks like its load is a bit too high for KT88, EL34, 6L6 etc (best around 6.6K). 8K looks best for EL84. Anyway, for PP you will need 4 KT88s, 2 output transformers and probably a different power transformer. With that power transformer perhaps you could go single ended and just need 2 KT88, but still 2 different output transformers.
For single ended I would suggest Tubelab SSE, stereo PP perhaps the Pete Millet universal driver board Push-pull KT88 class A amp with "universal" driver PCB Both are respected engineers with well designed products.
For single ended I would suggest Tubelab SSE, stereo PP perhaps the Pete Millet universal driver board Push-pull KT88 class A amp with "universal" driver PCB Both are respected engineers with well designed products.
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I haven't received them yet, I ordered them on Friday (Feb 3rd).
In reading info on the Tubelab.com website, it doesnt look like I could use any of the parts I ordered in their SE or PP.... are you suggesting returning my items and going with something more simple like that to start off? Or could I somehow use the stuff I bought to make one of the Tubelab amps?
If I was going to change my Edcor order to power the ODDBLOCK PP KT88 project better, which transformers should I change to?
In reading info on the Tubelab.com website, it doesnt look like I could use any of the parts I ordered in their SE or PP.... are you suggesting returning my items and going with something more simple like that to start off? Or could I somehow use the stuff I bought to make one of the Tubelab amps?
If I was going to change my Edcor order to power the ODDBLOCK PP KT88 project better, which transformers should I change to?
Bobby2sox, did u order parts, for a pair of push-pull kt88s the optimum load is 4200 plate to plate, the oddwatt design uses cathode follower design. cathode follows are good for preamps and phono stages, there output impedance and voltage output arent really very compatable to power tubes. Ive seen them used in single ended in fact i used 6sn7 in SSRP in my headphone amp using kt77s power tubes in single ended, the sound was good but better range can be covered with a good pentode front end or triode.
If you didnt get the parts u should consider a dynaco replica, Ill paste the link to the dynaco catalog, in PDF. There is a couple KT88 amps in there, push pull and a parallel push pull, I built the PPP and it is awesome, 120w and a great range, full. anyway edcor has the transformers, the link Im sending has the transformers at the bottom match transformer numbers with amp u desire, just call edcor and rattle off the voltages and milliamps of the power supply and the impedance and wattage of the output for the amp you want to build and they will cross with theres. they have a excellent transformer and the parmeters are identical to the dynacos.. if you go the ppp the load impedance of the output is 2100 ohms..look at the pdf and u can put 2 and 2 together... been building amps for 30 years and the KT88s are powerful, great pic.. you can swap out for 6550 exact same tube just different envelope...good luck let me know what you go with..
http://www.bunkerofdoom.com/xfm/DYNACO_01/Dynaco_01.pdf
If you didnt get the parts u should consider a dynaco replica, Ill paste the link to the dynaco catalog, in PDF. There is a couple KT88 amps in there, push pull and a parallel push pull, I built the PPP and it is awesome, 120w and a great range, full. anyway edcor has the transformers, the link Im sending has the transformers at the bottom match transformer numbers with amp u desire, just call edcor and rattle off the voltages and milliamps of the power supply and the impedance and wattage of the output for the amp you want to build and they will cross with theres. they have a excellent transformer and the parmeters are identical to the dynacos.. if you go the ppp the load impedance of the output is 2100 ohms..look at the pdf and u can put 2 and 2 together... been building amps for 30 years and the KT88s are powerful, great pic.. you can swap out for 6550 exact same tube just different envelope...good luck let me know what you go with..
http://www.bunkerofdoom.com/xfm/DYNACO_01/Dynaco_01.pdf
Easy there...
4.3k is recommended for a kt88 in a conventional push-pull output stage with fixed bias running Class AB1, but the OddWatt is none of the above (except for the kt88 part).
The OddWatt design uses a somewhat unconventional output stage. It resembles a LTP phase splitter.
6.6k or 7.6k impedance might be a better match but I would contact Bruce (the original designer) what he thinks first.
Bobby2Sox, You are on the right track to build The Oddwatt design, but you only have enough parts for one channel. You might need a second power transformer, 250mA might not be enough for both channels. 3A 6.3v is close enough for the kt88s for one channel (which would be 3.2A). You will need a separate filament power supply for the 6sl7/12sl7/5751. You will also need two more kt88s. The Oddwatt design as is only one channel, you will need to make two amps for stereo.
4.3k is recommended for a kt88 in a conventional push-pull output stage with fixed bias running Class AB1, but the OddWatt is none of the above (except for the kt88 part).
The OddWatt design uses a somewhat unconventional output stage. It resembles a LTP phase splitter.
6.6k or 7.6k impedance might be a better match but I would contact Bruce (the original designer) what he thinks first.
Bobby2Sox, You are on the right track to build The Oddwatt design, but you only have enough parts for one channel. You might need a second power transformer, 250mA might not be enough for both channels. 3A 6.3v is close enough for the kt88s for one channel (which would be 3.2A). You will need a separate filament power supply for the 6sl7/12sl7/5751. You will also need two more kt88s. The Oddwatt design as is only one channel, you will need to make two amps for stereo.
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But I could use the items I purchased to build one half of a set of monoblocks? Without making any changes? Then I could just buy the same parts again and build another one after I have the practice with the first one.
Thanks for the help!
Thanks for the help!
Transformers from Edcor are made to order, thats why the long lead time before shipping. I am not sure if they accept returns.
Sal
Sal
If you also buy the SMPS, or a separate filament transformer, to provide the heater voltage to the KT88s, then yes. The required heater current for a pair of KT88s is 3.2A. The transformer you purchased can only provide 3A. You can use it for the 5751 heater.
They may accept a change of order if they have not yet manufactured the transformer. Worth asking if you want to change design. If you want to build the (odd watt?) design I guess you can if that is the specified device. I though that odwatt make kits, so you could just purchase a kit with everything included.
I must respectfully disagree with this statement. 3A is 3A. 3.2A is more than 3A. It may run hot if you do this, or at the very least you will end up with an under-voltage filament supply.
Unless of course you have confirmed with Edcor that the filament winding will indeed supply 3.2A.
Personally, If it was all I had I would we willing to try it out as long as it doesn't exceed more than 10% over the ratings.
However; you are right, I shouldn't suggest to someone to exceed the specifications of a power transformer.
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