| ThSpeakerDude88 |
Any experience with this opt? I'm thinking about a MKIII or ST35, as I have two 1650F's.
What about power xfrmr? I have been hearing that the 270/272/370/372HX series wil work ok, which one is the best? |
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| Sherman |
No personal experience with the 1650F but it has a primary Z of 7.6K while the MK III trafos were 4.3K. It is also rated for 25W while a MK III is a 60W amp.
So... it would be better suited to an ST35 with EL84 power tubes. Both the impedance and the power rating are well matched to the 15W or so the ST35 makes. You might also consider Uncle Ned's ST35 "kit" based on DIYTUBE PCBs. Should be a good match.
The 270HX would supply enough current and voltage, lower models in the 270 series would be light on current depending on your biasing.
The 3xx series have a larger core and are beefier all around than the 2xx series PTXs. I've used several 2xx series and all had some degree of mechanical buzz which I mitigated by mounting on rubber washers. The 3xx series reportedly are much quieter mechanically and less "on the edge" at their rated output.
HTH, |
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| Eli Duttman |
| quote: | Originally posted by ThSpeakerDude88
Any experience with this opt? I'm thinking about a MKIII or ST35, as I have two 1650F's.
What about power xfrmr? I have been hearing that the 270/272/370/372HX series wil work ok, which one is the best? |
The ST35 circuit and "El Cheapo" should be OK with the 1650Fs. Forget about KT88s, as the end to end impedance is too high and the power handling capability is too low.
IMO, it's HARD to better the price/performance of a properly executed voltage doubler B+ supply. Revered designs, including the H/K Cit. 2, Marantz 8B, and Fisher 500C, use doubler PSUs. ;) |
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| ThSpeakerDude88 |
sorry, I didnt mean mkIII, I was thinking of this schematic http://www.ampslab.com/SCHEMATICS/Dynaco6BQ5.gif.
El-Cheapo looks like a nice circuit to breadboard , I may try a mono to see what I thinkbefore building. Also, I have a 270FX. I know it is rated at 150ma, but with solid state rectification and no use of the 5v tap, would my current capability be better? If its not even worth messing with , I will order a 370HX. However, its what I have for now. |
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| Eli Duttman |
| quote: | Originally posted by ThSpeakerDude88
sorry, I didnt mean mkIII, I was thinking of this schematic http://www.ampslab.com/SCHEMATICS/Dynaco6BQ5.gif.
El-Cheapo looks like a nice circuit to breadboard , I may try a mono to see what I thinkbefore building. Also, I have a 270FX. I know it is rated at 150ma, but with solid state rectification and no use of the 5v tap, would my current capability be better? If its not even worth messing with , I will order a 370HX. However, its what I have for now. |
With the 5 V. winding inactive, you should be OK with the 270FX. At "idle", El Cheapo draws approx. 132 mA. CLC fiiltration of the B+ using the minimum amount of capacitance in the 1st position necessary to keep the rail voltage up allows you to squeeze a few extra mA. out of the rectifier winding. A Hammond 159S looks OK as the B+ PSU choke.
BTW, tube rectification is OK. A 6BY5 dual damper will get the job done nicely. The 5 A. rating of the 6.3 V. winding is not stressed. 4X 6AQ5s or 6V6s draw 1.8 A. of heater current. A 6BY5 draws 1.6 A. 2X 12AT7s draw 0.6 A. The total heater draw is a comfortable 4.0 A. Don't directly ground the 6.3 V. winding's CT. Grounding via a large 'lytic is OK.
You can use the B- supply shown in the "El Cheapo" schematic. Use a 6AL5 for the vacuum half of the bridge and power its heater from the B- power trafo. |
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| dmason |
| I have a pair in a Class A PP triode 6EM7. They are surprisingly musical, with good low end grunt. Outstanding value IMO. Hope this helps abit... |
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| ThSpeakerDude88 |
I have the other 1650F on the way. I found a comparison to the original dynaco opt's and the hammonds are close and great for the price.
About the power x-frmr: Can I use SS FWB ? I thought that if you did that, instad of using the x-frmr centertap, that you could dish out more current because you weren't passing DC through the x-frmr windings. |
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| Eli Duttman |
| quote: | Originally posted by ThSpeakerDude88
I have the other 1650F on the way. I found a comparison to the original dynaco opt's and the hammonds are close and great for the price.
About the power x-frmr: Can I use SS FWB ? I thought that if you did that, instad of using the x-frmr centertap, that you could dish out more current because you weren't passing DC through the x-frmr windings. |
Dude,
If you bridge rectify the end to end voltage of the rectifier winding, you get twice the V. and half the A. Surprise (NOT), TANSTAAFL applies. The rectifier winding has a fixed VA rating. Also, there is no "standing" DC, when the "classic" FWCT circuit is employed. |
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| ThSpeakerDude88 |
I meant the B+ winding, not the rectifier winding.
Please explain more about FWCT? I was told that each half swings +/- from ground point and is rectified, and that DC flows through the ct. Maybe I am tired and confused... :xeye:
Now I know that with a standard non CT transformer if you bridge rectify you get ~1.414*Vac , and .707* I. |
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| ThSpeakerDude88 |
well, they have the 272/270hx, and the 300 series versions. The HX series are rated for 200ma. The other option, is a 302AX. It is rated at 200 ma also.. and I don't exactly see much difference between it and the 370 HX.
Here are my main questions: How much current does a typical 15-20 watt/ch stereo 6bq5 amp need ( with safe headroom to prevent overheating the xfrmr)
What voltage should I choose... 275v or 300v. 275v will be easier on the tubes wont it? Also, there is a huge price difference between the 200 and 300 series.
a 270HX is $62, while the 370HX is $93. Is it really worth the extra bucks, with enough current on tap ( assuming I am running 120v into a 117v xfrmr for the 200 series.)
the extra money could go into some good coupling caps if I went the 200 route... what do you guys think? |
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| ThSpeakerDude88 |
Didn't think of that... However it does appear at least to be cheaper made than a hammond..
Of the hammonds which would you reccomend. While the triodeelec trafo might be ok, isnt the B+ a little tough on EL84's? I figured that with the hammonds I could drop B+ a little and not stress the tubes as much.. |
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| TheMooN |
Hey Brett
Would you mind PM'ing me please ! would like to run something past you regarding your amps !
Rgds
Roger |
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| Brett |
| quote: | Originally posted by TheMooN
Hey Brett
Would you mind PM'ing me please ! would like to run something past you regarding your amps !
Rgds
Roger |
Hi Roger,
I tried, but you have the options set up so I can't, and I don't publish my email addy. You'll need to PM me. |
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| TheMooN |
| quote: | Originally posted by Brett
Hi Roger,
I tried, but you have the options set up so I can't, and I don't publish my email addy. You'll need to PM me. |
Nice to hear from you Brett !
Curiously I do have Pm enabled in user options and I cannot see a PM link for yourself :confused: shall enable email also |
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| Brett |
| quote: | Originally posted by TheMooN
Nice to hear from you Brett !
Curiously I do have Pm enabled in user options and I cannot see a PM link for yourself :confused: shall enable email also |
I just checked my options and PM's are enabled. When I clicked on the email link in your profile I got this.
Sorry! That user has specified that they do not wish to receive emails through this board. If you still wish to send an email to this user, please contact the administrator and they may be able to help. |
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| TheMooN |
Admin ~ Yes Have done so as we speak in the meantime perhaps
felixkat(at)f2s9dot)com should assist !
Speakerdude88 ~ My apologies for messing up your thread Sir ! |
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| ThSpeakerDude88 |
Its ok! :)
Anyways.. Brett, any experience with the DynaClone PT? It seems good for the price, looks a little cheap compared to the hammonds. I would like to order my PT SOON because I am getting anxious!
Also, any good reccomendations on output tubes? I understand certain brands can take the extra HV better than others. |
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| Brett |
| quote: | Originally posted by ThSpeakerDude88
Anyways.. Brett, any experience with the DynaClone PT? It seems good for the price, looks a little cheap compared to the hammonds. I would like to order my PT SOON because I am getting anxious! |
Nope. I've got original Dyna's. |
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| ThSpeakerDude88 |
| ah ok, I was wondering because the old ones were designed for 117v. I would like them to be designed for 120v to keep them running cool and not bang the output tubes so hard. Have they redone this on the new dynaclone PTs?? |
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| Brett |
| quote: | Originally posted by ThSpeakerDude88
ah ok, I was wondering because the old ones were designed for 117v. I would like them to be designed for 120v to keep them running cool and not bang the output tubes so hard. Have they redone this on the new dynaclone PTs?? |
Dunno. I have no interest in the PT's as I live in a 240V country. Email Ned. |
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| kevinkr |
| quote: | Originally posted by Brett
Dunno. I have no interest in the PT's as I live in a 240V country. Email Ned. |
Ned Carlson has started his own outfit, no longer at triode electronics. (Left about 2 yrs ago)You'll find him here: http://www.tubezone.net/index.html |
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| Brett |
| quote: | Originally posted by kevinkr
Ned Carlson has started his own outfit, no longer at triode electronics. (Left about 2 yrs ago)You'll find him here: http://www.tubezone.net/index.html |
Thanks for the info. Just shows how long since I've ordered something from there. |
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| ThSpeakerDude88 |
Still no answer on power a power supply........
I really just need to know if the newly designed power transformers for the ST35 are copies of the original , which seemed to run hot from many accounts I've read, or if they are new improved versions that will run cool.
If so I'd like to order one from triodeelectronics this week. |
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| Brett |
| quote: | Originally posted by ThSpeakerDude88
Still no answer on power a power supply........
I really just need to know if the newly designed power transformers for the ST35 are copies of the original , which seemed to run hot from many accounts I've read, or if they are new improved versions that will run cool.
If so I'd like to order one from triodeelectronics this week. |
I remember a couple of years back when these were released, there was a bit of talk on AA TubeDIY about them being redesigned to get over the overheating issue.
Also, whilst I have direct experience of them, the 2 series Hammonds had a rep for running hot according to AA pundits. The 3 series were reportedly better. Unless cost or weight are an issue, I buy the biggest iron I can. |
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| ThSpeakerDude88 |
| I have heard the same thing about the hammond 2x series, and that is why I was going to go with either a 3x or the dynakit one. That is some reassuring information, I'll do a little more research on it, but it is looking like that is the one I am going to get. |
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| JimW |
| I have used the 3xx series in several projects without any problems. They have been quiet and run cool. I have an amp in my office that gets switched on at 6am every moring, runs until 5pm, and except when the air conditioning went down, never gets more than warm to the touch. Without the ac it got noticeably warmer, but not hot. Never tried the 2xx, heard too many stories about running hot, but I don't recall reading a lot of stories about failures. I have also used the angela universal in a couple of amps - they are very quiet. They do run a little warmer than the 3xx hammonds, but nothing to worry about. |
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| ThSpeakerDude88 |
| I have a 269ex in my guitar amp, and it runs hot! not so hot that you can't hold onto it, but warmer than I'd prefer. I think it is because I am stretching the heater tap a little? I'm running two 12ax7's, an ek84 and ez81. |
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| ThSpeakerDude88 |
well I ordered the one from triode electronics. Matches the Hammond OPT's perfectly!
Now I have a question about placement. On the ST35, and a lot of other amps, the power transformer is always at a 90 to the OPT's. Does this really reduce hum enough to warrant this location or was it originally done to save room? I think it would at least look better with them all in a neat row, like mcintosh amps. |
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| Brett |
| When you build it, try it without bolting it down. If there's hum, rotate it, if not, leave it the way it looks best to you. |
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| ThSpeakerDude88 |
| hey thanks! My problem is I already drilled holes for a hammond 2xx series x.frmr. I dunno why I did that, I think I forgot I was ordering a new xfrmr :xeye: Don't you hate those days? Once I get the chassis polished I'll post some pics up here. Cheers! |
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| tommcnally |
| quote: | Originally posted by dmason
I have a pair in a Class A PP triode 6EM7. They are surprisingly musical, with good low end grunt. Outstanding value IMO. Hope this helps abit... |
How is my amp doing anyway Dan ?
I haven't heard from you in a long time.
shoot me an email
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| whitelabrat |
I just got my hands on a 373BX. Compared to a 274BX that I also have it is quite a bit larger and heavier! Something to think about. I got it dirt cheap, but will probably crush the $6 cake pan I was going to use as a chassis.
It's likely a get what you pay for deal. My 274BX hums like mad, gets very very hot, and it's primaries are rated for 115v. I haven't wired up the 373BX yet, but the word is that they run cooler and don't hum like the 200 series. 120v primaries are a plus as well. Check out Edcor's offerings too. I haven't had any experience with them, but plan to purchase from them soon. |
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| kevinkr |
| quote: | Originally posted by whitelabrat
I just got my hands on a 373BX. Compared to a 274BX that I also have it is quite a bit larger and heavier! Something to think about. I got it dirt cheap, but will probably crush the $6 cake pan I was going to use as a chassis.
It's likely a get what you pay for deal. My 274BX hums like mad, gets very very hot, and it's primaries are rated for 115v. I haven't wired up the 373BX yet, but the word is that they run cooler and don't hum like the 200 series. 120v primaries are a plus as well. Check out Edcor's offerings too. I haven't had any experience with them, but plan to purchase from them soon. |
The Hammond 300 series stuff are quite a lot better than the 200 series transformers, you would hardly believe they are made by the same outfit. (Better = much quieter, cooler running)
:D |
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