Products:
10 x CAP-100-R-50U-16V-NP: 50uF 16V Audio Note Kaisei NON-POLAR Electrolytic Capacitor - £42.30 (£4.23 each)
SKU:CAP-100-R-50U-16V-NP, Location: AB03, Tariff Code: 8532220000
8 x ELNAS-125: 220uF 25V Elna Silmic II RFS Elektrolitik Kondansatör - 11,44 £ (her biri 1,43 £)
SKU:ELNAS-125, Yer: AJ10, Tarife Kodu: 8532220000
3 x ELNAS-179: 1000uF 25V Elna Silmic II RFS Elektrolitik Kondansatör - 8,61 £ (her biri 2,87 £)
SKU:ELNAS-179, Yer: AJ10, Tarife Kodu: 8532220000
I was stating to check connections not what type.
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lufubu After adding the C704, my spatial transmission also decreased, the amount of air also became smaller, but the timbre sound became more correct. After about two weeks, everything leveled off, but reached a maximum after a month.
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Both effects the sound quality. It adds dynamics in addition to the added free gain.
A question for the experts: With the modded DS (Lundahl+VOCM+C704) I got some unexpected “additions” on very low frequencies at high output levels.
I noticed it very rarely and couldn´t make out what the problem was. First I thought I killed a speaker, at least that´s what it sounded like.
It really took some listening time to find out, but now it is reproducable. Unfortunately I have no measuring equipment to check, just a simple circuit analyzer (multimeter).
When I use the volume control within the DS it is never audible, but just and only because I will never reach the “critical” output level.
When the DS is connected with balanced ICs to my pre, so running with a fixed output level at the recommended 90-92, I get some kind of soft “clipping” or “stuttering” on very low frequencies, let´s say below 50 Hz. When I reduce the DS´s level by 10 or 15 and raise level on the pre accordingly, everything is fine, sound is still excellent.
I tried serial and parallel mode with the Lundahls and it´s the same, just the critical volume being different by approx. 10 ticks, which is the expected level difference between the two modes. (“Critical” value for serial is around 90, for parallel it is around 80.)
It is hard to describe, but yet apparent for example with the beginning of “O Vazio” by Jim Brock Ensemble (Reference Recordings, RR-910 from 2010). There is a very deep and room filling bass at around 0:32. When the DS´s volume is set too high the problem is clearly audible. I used some test tracks (sinewaves) to reproduce this and to avoid influences of the special recording used. It is a matter of frequency and level.
After all it´s not a big deal, just choosing the right volume and everything is fine. I am just curious what the cause my be. The transformers? The C704 caps? What else? Maybe someone´s got an idea… or is willing to try to reproduce it for himself.
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I run a preamplifier and do not hear anything like your describing. I run my DS at 94 as that gives the correct reference output level. My measurements did not show any issues ether. I would double check your connections of the VOCM caps.
A question based on only my intuition: Did you use non-polarized caps for C704?
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Only the recommendation for the R6 cap was polarized, correct?
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The cap over R6 may be polarized, it doesn’t have to be. C704 should not be polarized.
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What preamp are you using?
Thanks for letting me know. I just brought the board in to have the connections checked. I hope I get it back before Christmas! I’ll keep you posted on the results.
Thanks for your suggestion. I checked the VOCM caps and measured the resistance from leg to leg on the caps when installed to the board. In fact I am measuring the resistance of R6 in that configuration (correct me if I´m wrong). It gave me a constant reading of 123 Ohms for all 8 caps. So I guess that is fine.
I use this caps for C704 and they are non polarized (film) caps. I followed @yuriy ´s recommendation on that and I hope he can check his DAC accordingly.
It is a PASS XP-12. Do you think that it can have an influence on that? Because when I reduce the DS´s level by 10 or 15 and raise the level on the pre accordingly, everything is fine.
You want to test each side of the cap to ground (TP) in diode mode. One side will be a short the other side will show the same readings on all 8 caps.
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Could be…
Check it using single ended cables on input 3. Make sure you disconnect the XLR’s on the DS.
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The output of the DS is at the standard reference level when set to 94. The same as most all sources.
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Yes, I did. I am just about to sum it up. I tried every available in- and output on both the DS and on XP-12.
And I couldn´t believe it was normal and I am too curious as to accept things like that, so I reverted every modification, step by step and listened.
- Pull the JKR DC board
- Remove the C704 caps
- Remove the R6 VOCM caps
- again change between serial and parallel mode on the adaptor boards
- check and resolder the Lundahls and adaptors
- and at last exchanged the Lundahls with the XS4400´s with secondaries in series (see #4505, special thanks to jkrichards!)
I took a listen after EVERY step (weather is bad and holiday has come, you know) and I had to proceed to the very last step to clean it up.
I am sure the Lundahls were connected correctly, soldering was fine and resistance and continuity measurement was perfect.
I don´t know why, but they just do not work here as expected. What a pity! So I´ll go without them.
One question remains: Is it beneficial to perform the VOCM and/or C704 mod in addition to the XS4400´s in serial mode? Well, I will see, but for now I´m done with experiments.
Yes, and with the 4400´s I can even set the volume on the DS to 100 without any audible problems. That is how it should work.