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TSE build need help

I'am having a low end distortion issue with mt TSE build , bass is weak, tubby and distorted mids and high's not so bad. Here is what I have so far:
Hammond 270 FX pt
Hammond 158 m choke 10H 100ma
5R4 rectifier
NOS 45's test as new
310v B+
30ma bias
5842 mp jan
175v on 5842
James 6113 opt's using 5k
no volume pot in input
using 98db efficient AN speakers
I have triple checked everything but no luck. sound is equally bad in both channels
Please help :confused:
 

zxx222

Member
2005-08-01 8:23 am
b
Transformer saturation? Normally should not be the case - James 6113 are rated 10W 27Hz~60KHz-2dB.
Anyway, I would not expect deep bass from these transformers - I use James 6123 iron in my TSE and in comparison to it, SSE with Edcor cxse iron is clear winner in bass.

Another reason might be clipping - as I understand you are not using volume control, so obviously you use some kind of pre amplifier - it might be overloading TSE. Search "TSE input" - in that thread boywonder wrote:

"I happen to have both of my tubelab SE's on the bench right now; a 45 version and a 300B version.
The 45 version clips at approx 1V RMS input and the 300B clips at roughly 1.5V RMS input.
I'm just eyeballing the sine wave for distortion/asymmetry on the scope at 60 hz and 10Khz."

Check your source.
 
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With only a few voltage readings to go on, which seem to be correct, it is hard to tell what is wrong.

Is the filament voltage on the 45's correct? You should have very close to 2.5 volts. Is the heater voltage on the 5842 close to 6.3 volts, this can vary due to transformer and line voltage differences?

It is possible that the input stage could be oscillating due to the way the wiring is routed, especially without a volume pot. Are both channels the same?Does running your finger (CAREFULLY) around the glass on the 5842 change anything? Does moving the wiring on the input change anything?

Can you post some good pictures of the PC board, and the wiring to it? Several issues have been found in the past with multiple pairs of eyes looking at it.
 
With only a few voltage readings to go on, which seem to be correct, it is hard to tell what is wrong.

Is the filament voltage on the 45's correct? You should have very close to 2.5 volts. Is the heater voltage on the 5842 close to 6.3 volts, this can vary due to transformer and line voltage differences?

It is possible that the input stage could be oscillating due to the way the wiring is routed, especially without a volume pot. Are both channels the same?Does running your finger (CAREFULLY) around the glass on the 5842 change anything? Does moving the wiring on the input change anything?

Can you post some good pictures of the PC board, and the wiring to it? Several issues have been found in the past with multiple pairs of eyes looking at it.

45 filament v 2.45
5842 filament v 5.8
running finger around 5842 glass no effect
moving input wiring around has no effect
 
Voltages look OK, so my guess is ..... the 45 does not have enough power to suit your listening requirements.

I don't know what a 98 dB AN speaker is, but I have 96 dB Klipsch's and it is the norm to run the small DHT's like 45, 2A3, and even 801, out of gas on deep bass at more than moderate listening levels. And it sounds just like you describe - weak, tubby, and distorted. It is not at all subtle.

If you are used to 300B's, the 45 is at least 6 dB down from that. Big difference.

The small DHT's are not for everyone. They are exceptionally linear within their limitations, but the limitations are fairly severe. They are not room shakers until you get to the bigger ones. Much bigger.

Win W5JAG
 
thanks for the advice but trust me power is not the issue. Audio Note speakers are designed for DHT low power amps. My 300b amps at 5 or so watts will blow the roof off so
with 45's I expect good sound at very modest sp levels as my room is fairly small it's ideal for low powered dht's. I will post some pic's of my build as soon as I figure out how.
 
Sylvania 45's .47 caps and yes i have tried various rectifier tubes both NOS and new. Last night I reconfigured the jumpers and installed a pair of 300b's at 360 b+ and 75ma bias. This arrangement sounds much better, nice sound stage and the bottom end is much improved, the vocals are still a little raspy to my ears but I'll pass final judgement after some break in time. I must say it's the quietest 300b amp I have owned no hum at all even with my ears right at the speakers.
 
The caps are Mundorf surpreme . I will lower the 5842 v tonight and try it. I only have about 10 hrs on it now because it sounds so bad. I ran it last night for about 5 hrs with the 300b's and where it's better than the 45's it's still pretty bad too much distortion.... I tried both 3K and 5K taps to no avail.
 
When I built my TSE a couple of month's back I had installed a 350 volt cap in position C6 and C7. C6 eventually blew (more like poped and fizzeled open). Up until then the amp displayed a tendency to distort on bass peaks. The parts list does indicate 450v in that position. I replaced C6 and C7 with United Chemi-Con 450 v high temp and long life rated caps. That first cap takes a big hit on turn on. I Installed a Thermistor inline with the bias supply and I measure a nice slow climb in voltage when starting cold.
I have absolutely no great skills in this beyond s very basic understanding. I used to troubleshoot wiring problems in ambulances though. Circuit theory and the math that accompanies it is Greek to me.