Bottlehead Forum
Bottlehead Kits => Legacy Kit Products => Smash => Topic started by: 1026mind on February 16, 2022, 10:03:13 AM
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I had built the smash a few years back and it worked fine, well the usual noise and microphonic. So I decided to do the smashup upgrade and to build it on two chassis , one the power source and the voltage regulators and the rest on the second chassie .
I finished the power supply but I am getting different voltages
B1-0v
B2-212v
B3-1.847v
B4-0v
B5-212v
B6-1.847
Please help!!
Thank you!
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I would post build photos if you can. I haven't provided tech support on a Smash-up in some time, so a visual inspection is a good place to start.
On the surface, I see the same issue on both sides, so it's likely that the same mistake made it onto both boards or into the build on both sides.
The 1.8V on the cathodes means the 6SN7 triodes are sucking down a ton of current.
What are your OB voltages on each PC board? If for some reason the 4P1L tubes aren't drawing any current, that could possibly cause some of the issues you're experiencing.
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The 4P1L are not in place, I only completed the power supply and the voltage regulators . The OB voltages are the same with B2 and B5.
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If you don't have the 4P1L tubes drawing the appropriate current, it won't really be possible to ascertain whether there's any issue that needs to be resolved at this juncture.
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I will build the second part and go from there. Thank you very much!
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I completed the second part, the voltages are:
B1 - 0V
B2 - 208.5V
B3 - 9.92V
B4 - 0V
B5 - 107.5V
B6 - 1.835V
IA - 210V Both sides
OB - 62V Both sides
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What are the Kreg voltages on the regulator board?
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9.95V and 1.8V
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Well I would check to be sure that the Kreg cathode connections are connected to the appropriate plates at the regulator tube. If you have plate A and cathode B hooked up to the same high voltage regulator, then you can get weird problems like this, and this is a pretty common problem with highly customized builds like this.
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they go to B3/kreg and B6/kreg for the cathodes and B2/OB, B5/OB for the plates.
the voltages where the same in the power source for both sides before I build the second part
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But B2 and B3 need to go to one side of the regulator board and B5 and B6 need to go to the other.
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They do
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I would next be looking for things like backwards LEDs or any transistor/431 device that has continuity between any pairs of legs.
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The 431's are good
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I'm not sure what other help to offer. Since your build deviates rather substantially from the kit we provide, the amount of help I can provide is a bit decreased.
What jumpers did you install on the regulator board?
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OB to +reg to Breg
-reg to bA
so if I disconnect the power source and measure voltage at !50V L and !50V R I get 212V, after I connect to the rest I get 107.5 and 208.5?????
I really appreciate your help
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The presence of a high Kreg voltage on one side of the regulator suggests that side should work. The low Kreg on the other regulator suggest that side would not.
Do your jumpers leaving OB go to Breg and +Reg on the B side or the A side?
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The Ob jumpers where wrong, they where going from left side to right, rewired and the voltages are in line now.
THANK YOU VERY MUCH!!!
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So it's working but is still very noisy. (:
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What kind of noise?
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floor noise
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What amplifier are you using and what speakers are you using? (or alternatively how much gain does your power amp have any how sensitive are your speakers?)
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Cambridge Audio 851N one per channel and Klipsch La Scala clones that I build.
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Yeah, I figured you either had a ton of amplifier gain (20+dB) or highly sensitive speakers, and you have both! I would use some Harrison Labs -12dB attenuators at the input of each amplifier to reduce sensitivity a bit, or consider a lower gain/lower power amplifier.
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Long time ago I purchased the last two suductor amps kits that you sold, would this work along with a Thorens turntable and the Eros that I build already?
t
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The Seductor will knock the noise down by about 12dB. You may prefer the Seductor and some -12dB attenuators to really knock things down.
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Got it, parts express have the atenuators they are 12db not -12db
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I went from 2 amps to 1 and the noise went down a little but I noticed that there is noise even without the smash powered up. its that normal?
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That is a bit abnormal. You could try this mod:
https://forum.bottlehead.com/index.php?topic=11676.0 (https://forum.bottlehead.com/index.php?topic=11676.0)
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Huge improvement, about 75% of the noise gone, the La Scala's really came to life!!!
Thank you very much!
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In your build where does the power supply connect to the chassis?
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everything goes to a grounding post.
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You have umbilicals in your build, so is each chassis plate connected through the umbilical?
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they are two umbilicals, one for the filament of the 4p1l's that is two wires and the other has 3 , one is ground and the other two are both 150v, one for each channel .
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so you have each chassis plate connected through the audio ground?
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yes Sir
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That is a potential source of noise. Ideally you would have the chassis plates connected together through their own wire in the umbilical and that would be hard grounded to the E lug on the IEC power entry module, then the audio/power supply ground would run separately and you would put the antiphase diodes in the amp section between the audio ground and the chassis.
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audio ground would be the part where the RCA are connected to the ground?
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never mind my last comment
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just finished and its still a little buzz
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now I don't know if you noticed but I don't have the pots nor the attenuators at the input, I'm just using the volume from my OPPO player.
could that be the reason for the little buzz/noise?
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What is at the input of the pre? Just jacks wired to the grids of the 4P1L?
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yes
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You should have a 47K resistor from grid to ground on each 4P1L. If you pull the RCA cables, the grid has no ground reference and that can cause damage to the 4P1Ls.
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when I purchased the smashup upgrade I got the smash quiet to. I want to built it but I have do diagram. Is it possible to get one?
Thank you! Btw I'm waiting on the attenuators, they are in the mail from France
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I'm not certain I made one for the Smash-up. When I have built it into other stuff, I just mount the attenuators and terminal strips on the plate we provide, then integrate that into whatever project I'm working on.
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Thank you!