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Old 25th May 2009, 08:02 PM   #61
ipop07 is offline ipop07  Canada
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Alright guys, thanks a lot, I just read George's notes about benefits and drawbacks of the transformers he used...So I kind of made my mind...now I am still not sure which tubes to grab since I never worked with tubes (I play bass guitar and I have a solid state Ampeg so not even there).....

One quick question: how vital is the choke to the quality of sound or freq range? or It doesnt really matter... Should I just go with the 193J or could I improve

I appreciate all the help....


P.S: I have the opportunity to grab Hammonds at factory cost for a short while, this is the reason I am going only Hammond...
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Old 27th May 2009, 09:06 AM   #62
fff0 is offline fff0  Singapore
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A choke helps to reduce the ripple in the power supply after rectification thus reduce noise. So it will help a whole lot.
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Old 27th May 2009, 03:28 PM   #63
rknize is offline rknize  United States
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I think he is asking if he can do better than the 193J (10H @ 200mA, 82 ohms). This is the choke that bread-boarded with and it worked great. I'm using one in my Tubelab SE build. The final chassis was built with the Triad C-14X choke from Allied that George likes to use (6H @ 200mA, 150 ohms). It's cheaper, but ugly. It also works fine.

The "quality" of the choke is not all the important in a pi-filter arrangement like this. Any choke over about 5H that has the proper current rating will work just fine.
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Old 27th May 2009, 03:37 PM   #64
fff0 is offline fff0  Singapore
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oopss... my bad.
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Old 27th May 2009, 04:00 PM   #65
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Quote:
Originally posted by ipop07
Alright guys, thanks a lot, I just read George's notes about benefits and drawbacks of the transformers he used...So I kind of made my mind...now I am still not sure which tubes to grab since I never worked with tubes (I play bass guitar and I have a solid state Ampeg so not even there).....

One quick question: how vital is the choke to the quality of sound or freq range? or It doesnt really matter... Should I just go with the 193J or could I improve

I appreciate all the help....


P.S: I have the opportunity to grab Hammonds at factory cost for a short while, this is the reason I am going only Hammond...

FWIW, Hammond also has open framed chokes (157 series) that are less $$ that would also be suitable for the Simple SE. You can mount them "under the hood" if your chassis has the space, since they are not as pretty as the 193 series. Take the $15 or so savings, and apply it to tubes.


EL34's have great mids/vocals, KT88's have more punch and better bass (that's why many bass guitar tube amps use KT88's). You may want to try both....

There are many good/reliable new tubes to choose from these days; I planning on using Russian Mullard reissue EL34's and Gold Lion reissue KT88's in my SSE when it is completed. I picked both of them up used on the trading post here, and they both have been discussed here favorably. Do a search on EL34, KT88, 6L6GC an you'll get lots of opinions. The Chinese 6L6GC's available at AES are supposed to be able to take some abuse, and are very inexpensive. There is also JJ's, EH, etc etc

As already mentioned, larger transformers typically have better bass performance than smaller ones, but go too large and you may experience some HF rolloff. Most folks seem to be specing OT's ranging from 10W to 25W for this project.
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Old 27th May 2009, 05:41 PM   #66
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Quote:
The "quality" of the choke is not all the important in a pi-filter arrangement like this. Any choke over about 5H that has the proper current rating will work just fine.
Agreed. In this application any choke is far better than no choke, but in this application the quality of the choke is far down the
"impact" list. The quality of the choke is very important in a choke input filter circuit, and less important in the CLC circuit that is used here.

I usually use the really cheap Chinese Triad chokes and use the money saved to improve other items. The Triads are ugly and may need to be hidden under the chassis. What improvements are worth the money? OPT's, the supplemental power supply cap, the power transformer, the coupling caps, and the tubes, in more or less that order.

Quote:
but go too large and you may experience some HF rolloff.
The big Hammonds like the 1628SEA are very good in the bass department, but do cost a little bit of high end and detail due to their size. The large core passes even the lowest frequencies at full power, but all of that iron and copper absorbs considerable energy which reduces the overall efficiency. The little 125CSE sounds great on the high frequencies, but will distort on heavy bass. I have not tried the bigger transformers from the 125 series, but one of them might be a better choice. The 125FSE and 125GSE are reported to be good sounding but slightly ugly transformers.

So far my choice for the best sounding reasonably priced OPT has to be the big Edcor CSXE25-8-5K. See this thread:

Tubelab Simple SE with big honkin' Edcors?

I usually use the Allied 6K7VG power transformer which is made by Hammond. Many users have built their amps with the Hammond 274BX but some report an audible buzz from the transformer. The 374BX has been used by many with no reports of buzz and it doesn't get as hot.
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