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Old 9th November 2002, 04:45 PM   #1
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Default Just fired up my Zen V2

I have just tested and fired up my Zen amp. For those tuned in about a month ago I found out that the problem with my circuit was that I wired in some salvaged transistors for Q3 and got the lead outs wrong. An expensive mistake.
Anyway sofar the results are quite good. I have no noticable hum (apart from the transformer which buzzes a bit). However I am a little disapointed at the thin bass I am getting. Otherwise the sound is lovely and clean and detailed (tube without the mush). I have a few questions though.
1. I am currently driving it with a passive preamp. This isnt really keeping up. Do you think it might be the source of my thin bass.
2. I am running it at a slightly reduced current of 1.6amps, what effect might this be having on the sound.
3. for Q1 I am using an IRF150 which is cooking nicely, however I am using a IRF240 with an on resistance of 0.18 and its running uncomfortably hot. Do you think a substiution with a IRF150 would bring its temp down.
4.When I fired up I tested the votage at the gate to Q1 and it was at 4V. I have R4 set at max. I have made no further adjustment to this. Would adjusting R4 effect the tonal balance any.

Any pointers as to how I might improve the bass response would be appreciated.
Thanks in anticipation.

Shoog
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Old 9th November 2002, 04:54 PM   #2
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I have build a Zen and matched it with the Aleph L ,

the bass are deep and loud .

YES for the active preamp!!!
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Old 9th November 2002, 04:58 PM   #3
paulb is offline paulb  Canada
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Default Re: Just fired up my Zen V2

Quote:
Originally posted by Shoog
1. I am currently driving it with a passive preamp. This isnt really keeping up. Do you think it might be the source of my thin bass.
I bet if you added the front end as per ZenV4 you could keep the passive preamp.
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Old 9th November 2002, 05:03 PM   #4
fcel is offline fcel  United States
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Thin bass is most probably due to inefficient speakers that you are using. I've got good bass from Klipsch speakers but absolutely no bass from Maggie speakers. I have the original Zen amp.
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Old 9th November 2002, 05:59 PM   #5
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Default This is definately not the case.

I am using very sensitive vintage Isophon drivers which performed more than well enough with my Leak stereo20 Amp. Look elsewhere for a solution
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Old 10th November 2002, 02:11 PM   #6
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Shoog

If the bias is 1.6A, R15 of 1k or 1.2k instead of 1.5k might give you a tighter base.

JH
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Old 11th November 2002, 06:05 PM   #7
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Default I will try that.

I believe the best approach is to build a Bride of Zen and see what difference that makes. I will hold this sujestion in reserve.
Thank
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Old 12th November 2002, 09:26 AM   #8
miguel2 is offline miguel2  Portugal
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I think this thread raises an important question: what voltage and current (power?) is necessary to drive the Zen amp to get its full potential? Of course the speakers will have a big effect on this, but as the gain of pre amplifiers can be adjusted, it would be nice to have some primary figures to point at. I am currently building a ZV4 and I noted in the channel built that I need to increase a bit the gain of my tube pre. But what is the optimum figure?
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