According to George of Tubelab, the boards are not officially available, but people including myself have sent PayPal payments for the Simple P-P boards and he is sending them out. I should receive mine tomorrow.
Hello,
I've been listening to this little amp for a few weeks now and it's seems to be getting better all the time. I'm using RCA clear tops for drivers but I think the Amperexs are a little better in the low end and stereo imaging. I tried to use EL84/6BQ5 tubes again. And again no go. When I turn the amp on and as it warms up I can hear a hum increasing in volume with no music output. I quickly shut the amp down because it sounds like it wants to blow up. Can anyone help me troubleshoot my problem? Where should I begin? I have about 20 EL84s and they all test strong and I sure wish I can use them.
Regards,
David
What model is your amp? (when in doubt, post a picture please)
Are there any modifications?
you may fast recognize a 6P15 by double mica layers against 6BQ5. also, 6P15 have slightly different pinout, and G3 pin is separately wired and not conneted internally to the cathode as in the EL84 types. so, first let the 6P15 stay in, until you have done more researches
An externally hosted image should be here but it was not working when we last tested it.
Hello oneyedk,
I don't have any pictures of my amp but it should be the same as the one above. The only mod is the replacement of the pot with some resistors. There are no other mods done to this amp that I know of. My amp uses the 6P15 power tubes and this is afaIk the schematic:
From the various posts, it sounds like many owners of this amp are using EL84/6BQ5 with no problems. So, what could possibly causing my amp to hum badly when I use the 6BQ5 tubes?
TubeSteve, yes EL83 is not the same as a 6BQ5/EL84. What should I check next?
Thanks for your replies.
Regards,
David
I was wondering if there were different versions of the pcb, that's why I asked.
MOST "boutique" EL84's have an internal connection between pin 1 and pin 2.
JJ does not (hence the good results of some people)...
For 6P15P tubes, pin 1 and pin 6 are connected to g3. On the pcb connected with pin 3 (cathode).
So if you plug in a 'boutique" EL84 as described above on a pcb designed for 6P15P, you short g1 with cathode... Not exactly a good idea.
I should've warned people for this, but I always measure resistance between pins before I plug in a "not so direct" replacement tube.
Had to learn that the hard way.
--> it's actually Joe who put misleading info on their website, describing the amp as EL84/6P15, while it's actually 6P15 without mods!
3 possible solutions to your problem:
1) go with a good set of JJ's
2) remove pin 1 from your EL84 set (might not be so easy to do and has to be done carefully, you don't want arcing)
3) cut the traces to pin 1 on the pcb
MOST "boutique" EL84's have an internal connection between pin 1 and pin 2.
JJ does not (hence the good results of some people)...
For 6P15P tubes, pin 1 and pin 6 are connected to g3. On the pcb connected with pin 3 (cathode).
So if you plug in a 'boutique" EL84 as described above on a pcb designed for 6P15P, you short g1 with cathode... Not exactly a good idea.
I should've warned people for this, but I always measure resistance between pins before I plug in a "not so direct" replacement tube.
Had to learn that the hard way.
--> it's actually Joe who put misleading info on their website, describing the amp as EL84/6P15, while it's actually 6P15 without mods!
3 possible solutions to your problem:
1) go with a good set of JJ's
2) remove pin 1 from your EL84 set (might not be so easy to do and has to be done carefully, you don't want arcing)
3) cut the traces to pin 1 on the pcb
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This is really pretty strange. I wonder why TerribleT is the only one having problems with EL84 tubes? Have any of you other guys had to do any mods to run EL84's? I've only rolled the driver tubes in mine so far so I'm still using stock power tubes.
It's definitely not unheard of for Chinese amps to come from the factory with different circuits; I wonder if TerribleT got a version that doesn't match the schematic?
It's definitely not unheard of for Chinese amps to come from the factory with different circuits; I wonder if TerribleT got a version that doesn't match the schematic?
question is: why the 6P15 always replace by EL84?. 6P15 is a video tube and should operate more linear. The EL84 also asks different a DC operation point for best working. For the hum mentioned, just open the amp and check,.... normal procedure...
Solution #2: Snip off pin #1
Hello Oneyedk,
I chose solution #2. I snipped off pin one on 4 6BQ5s poped them in and they work perfectly. Thanks for your help. I can't say the RCA 6BQ5s are significantly better, but my initial impressions are positive. More clarity on voices (Anita O'day!) and slightly better separation of instruments in the sound stage. I'd need more listening time to fully evaluate the differences between the tube types.
I'm now itching to try some Russion teflon coupling caps and I'm also considering doing the triode mod. What are your thoughts on this? Again, thanks for the help. More ideas on how to improve this little amp from you Suppo owners would be welcomed.
Regards,
David
I was wondering if there were different versions of the pcb, that's why I asked.
MOST "boutique" EL84's have an internal connection between pin 1 and pin 2.
JJ does not (hence the good results of some people)...
For 6P15P tubes, pin 1 and pin 6 are connected to g3. On the pcb connected with pin 3 (cathode).
So if you plug in a 'boutique" EL84 as described above on a pcb designed for 6P15P, you short g1 with cathode... Not exactly a good idea.
I should've warned people for this, but I always measure resistance between pins before I plug in a "not so direct" replacement tube.
Had to learn that the hard way.
--> it's actually Joe who put misleading info on their website, describing the amp as EL84/6P15, while it's actually 6P15 without mods!
3 possible solutions to your problem:
1) go with a good set of JJ's
2) remove pin 1 from your EL84 set (might not be so easy to do and has to be done carefully, you don't want arcing)
3) cut the traces to pin 1 on the pcb
Hello Oneyedk,
I chose solution #2. I snipped off pin one on 4 6BQ5s poped them in and they work perfectly. Thanks for your help. I can't say the RCA 6BQ5s are significantly better, but my initial impressions are positive. More clarity on voices (Anita O'day!) and slightly better separation of instruments in the sound stage. I'd need more listening time to fully evaluate the differences between the tube types.
I'm now itching to try some Russion teflon coupling caps and I'm also considering doing the triode mod. What are your thoughts on this? Again, thanks for the help. More ideas on how to improve this little amp from you Suppo owners would be welcomed.
Regards,
David
That's a very good question. Tube rolling without research is pointless...
6P15 might be a good upgrade for EL84's 😀
(with bias adjusted)
teflon cap
most people disliked the teflon caps for sound. maybe teflon is really better in the cooking area....
most people disliked the teflon caps for sound. maybe teflon is really better in the cooking area....
I would never have picked up that an RCA 6BQ5 has pin 1 and 2 connected. Here is a RCA datasheet:
http://www.pmillett.com/tubedata/HB-3/Receiving_Tubes_Part_1/6BQ5.PDF
I cannot find a datasheet that shows this. Fancy that.
http://www.pmillett.com/tubedata/HB-3/Receiving_Tubes_Part_1/6BQ5.PDF
I cannot find a datasheet that shows this. Fancy that.
I'm definitely a rookie here, but does that mean that the RCA 6BQ5 is the outlier? Will most other EL84's work here (i.e. are pin one and two normally tied together?)? I've got a quad of Russian 6p14p-ev that I'd like to try in this slot.
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hum again: one thing i forgot: in the suppo el84 ( 6P15) amp the power tubes share a common cathode resistor which not so good in general( different gm of the tubes). but the hum easily may come from not matched power tubes and can be quite noticeable then. this will also increase distortion and cause transformer core satuartion
I was wondering if there were different versions of the pcb, that's why I asked.
MOST "boutique" EL84's have an internal connection between pin 1 and pin 2.
JJ does not (hence the good results of some people)...
For 6P15P tubes, pin 1 and pin 6 are connected to g3. On the pcb connected with pin 3 (cathode).
So if you plug in a 'boutique" EL84 as described above on a pcb designed for 6P15P, you short g1 with cathode... Not exactly a good idea.
I should've warned people for this, but I always measure resistance between pins before I plug in a "not so direct" replacement tube.
Had to learn that the hard way.
--> it's actually Joe who put misleading info on their website, describing the amp as EL84/6P15, while it's actually 6P15 without mods!
3 possible solutions to your problem:
1) go with a good set of JJ's
2) remove pin 1 from your EL84 set (might not be so easy to do and has to be done carefully, you don't want arcing)
3) cut the traces to pin 1 on the pcb
OneyedK, I think you are onto something here. I learned the hard way too. Recently, I turned my amp on, and I heard a hum that quickly grew louder. Before I could reach the power switch, I saw a bright blue flash in one of the Genalex Gold Lion El84 tubes (position 3 from left to right) and heard a pop. I quickly turned off the amp. Once I looked inside the amp, I could see that the cathode bypass cap was bulging. I tested the tubes too, and the one that shorted was dead... So much for the nice tubes. I wonder how I was able to play this amp for many hours without this problem before?
Anyway, I installed a spare Panasonic FM 220uF/25V cap and put the stock 6P15 tubes back in the amp. No problems at all since. In fact, it still sounds good with the RCA 6FQ7 clear tops in the driver tube positions along with the other upgrades I've installed. I'll keep the Gold Lions and replace the dead one, and use them in my Tubelab Simple P-P project later on.
This is embarassing for me to kill an expensive tube, but hopefully, others will save their money and use caution in following Suppo's claims for tube rolling. They really should remove their general claim on their Website that EL84s can be used interchangeably with 6P14P and 6P15 tubes with this amplifier. Do I regret buying this amp? No, it still sounds great and I didn't pay much for it. Would I recommend it to another friend? Probably not.
suppo
differences of components (here tubes) are not so clear in china to many people. thats where the trouble starts. exact working is not known.
differences of components (here tubes) are not so clear in china to many people. thats where the trouble starts. exact working is not known.
The datasheet states: "Pin 1 - Internal Connection - Do Not Use"
"Do not use" means "do not use"...
Nope, most EL84's will not work (or work too hard and die). Simply measure the resistance between pin 1 and the other pins, if it's not connected to anything else, you're safe.
--> JJ's are fine
6P14P-ev seems ok to me, but do those measurements, just in case...
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