audio-talk

I'll second that.. Very interesting..

I’ll third it.

Today's resistor switcheroo was in the power amp; the tail resistor on the input stage. In the model there is virtually no signal on this part as the model deals in perfect parts. In reality, the difference between the two halves of a diff amp appears here so again, pretty small signal. Wasn't expecting much.

Was able to switch between the two with amps on. There wasn't much in it to begin with in fact I got easily confused as to which resistor was in until going to large classical pieces. Then the incumbent was a bit confused compared to the Kiwame which was a 5W 300R compared to at that time, I didn't know what. There was not the usual differences I heard this time comparing metal films to the carbons; highlighted top end blah blah. But I preferred the purity and better tone of the Kiwame. Once I could discern the difference, I could hear it in other things but I wouldn't bet my house or even a beer on it.

Looking up in my past orders, it turns out it is a Multicomp Pro 3W wirewound 50p vs £1.50 Kiwame. I suppose it could be tempting to pop a Mills in there one day however only if I had nothing else to do. It took me 9 months to get the WW in there over the 4 resistors in parallel that were there from Owsters last. That was more of an improvement than this.

I'm tempted to play with resistors in the GM70 bias as they are directly in the signal path. After that there are only 3 more resistors in the whole system and two of them are input resistors to the line and power amps so could be worth it, The other is in the tail of the line diff amp.

After rebuilding the line stage from using the adaptors for the 12B4, had noticed over the last week, things weren't as super as they were. Before rebuild, I could play as loud as it would go without the glare I found annoying with the 6N6 but now, it was here again. Looking at the adaptors, noticed I'd used some Allen-Bradley as grid stoppers on one pair. So took out the CC resistors I had been using and in went the ABs. OK, better but still not back to where I was.

A while back when updating the GM70, had removed the 4 resistor paralleled array for the 4P1L cathode tail but also did a bunch of other things at the same time. Liked the result but didn't know exactly what bit contributed to the change. I used one of the resistors out of that parallel array now in the line stage tail. Replaced it with one of the removed metal film phono stage decouplers and was back in business. Whatever that resistor is, it was awful. A Kiwame will probably be the choice here for future as I need a 2W part.

But the AB grid stopper direction had me intrigued so yesterday replaced the g2 and g3 grid stoppers on the 4P1L driver with ABs. A little more glare reduction, far better tone and detail as well so not glossing over details leading to mush. I had already done the GM70 and 4P1L g1 with ABs a little time back but that was instead of ferrites. Didn't evaluate this as it was part of that many changes above. This morning replaced the phono grid stoppers with ABs and same result again.

All the replaced grid stoppers were Neohm CC. I was of the belief that grid stoppers just needed to be CC type and that was the job done. Only recently had I heard some folk using Audio Note tantalums in this position. Never mind the cost which is quite large and so not a starter for me, the idea grid stoppers were making a benefit to this degree I thought fanciful but hey, if you can afford it and get a benefit, great. Seems they do make a difference. There goes another prejudice. The ABs are cheap and on what I've just heard an easy choice from now on.

I had only switched to the Neohm as the batch of ABs I did have, which I got from the late Brian Clark on his recommendation, had run out. These are not rugged devices and the 1/4W ones, when soldered close to a valve pin, do suffer over the years from being soldered in and out many times. The 1/2W ones might be a better choice. Used 1W on the GM70.

Herb Reichert recommended AB’s if you can’t afford Tantallum in his Flesh & Blood article. 10 years ago I got to the tip a day late, I fished just one value of AB’s out but the skip had been switched day before and apparently was full of AB’s! Bu***r!

I heard from a forum memeber hwo is not contributing since long while now, that Nick atHifi Collective has a huge stock of AB’s.