I hope all this makes sense! Your comments looked forward to as I shall go no further on this project until I am sure! Thanks.Ok - was going to post this query separetely. I don't know whether there is an accompanying change in the resistor/cap values in that area to compensate. TR7(L) remained a 458 with an Hfe of 263. The only other change I have noticed had been in replacing TR7(R) from a 458 to a 2N2712 with an Hfe of 181. One of these gave a much higher Hfe than the 458's TR9(L) is 644 but TR9(R) is 240 - which is quite a lot of difference between even those two mini-cans. When I bought this machine new in 1983 already there had been some transistor changes - notably TR9(L) and TR9(R) where the original specified 2SC458LG (large gain? low gain?) they had put in a pair of can-type Transistors BC109. Most of them were in the range of 270 or so. The original 2SC458's ranged from 75 & 80 (only two that low) up to 339. The results I get from the KSC's range from 403 down to 339 - but mostly they are around 340-350. I have tested all those new KSC's but, because I am not really acquainted with the proper understanding of the resultant Hfe's am a bit at a loss. Is this the best way to choose from my transistor hoard? Should the TR1(L) be matched to TR1(R), or should all the transistors in each channel be as close as possible to being the same Hfe? Well, there are NO pairs in this of NPN/PNP, all the Transistors virtually 'daisy-chain' until the OP XFMR. Note: The DCA55 gave readings from the removed 2SC458's ranging from Hfe = 75 to 313 - all of which are well below the new Fairchild KSC1845's.
#Akai tapedeck gx 95 how to
Would someone assist me by explaining how to get the best matches for the two channels. The constants: Ic is 2.5mA, Vbe is 0.74v, Ib is 4.66 and Ic is 0.00. These KSC's, though new, show the Hfe readings range from 403 down to 339. and have a new PEAK DCA55 meter to help me. (Board: No.TH50001A as shown on the solder side) I have 60 Fairchild KSC1845's to choose from. My GX635D is on the bench with all 2SC458 transistors removed from both Left and Right channels in the Pre-amp. Thank you in advance for any advice you may have. A head not-alignment it’s also questionable since the tape plays great in both direct and reverse mode when it’s NOT flipped. The same preamps are being used to play the tape in direct mode, reverse mode, regardless if you flip it or not. This is very strange, why such in-balance when I flip the tape while it’s playing perfectly if the tape it’s not flipped. Same happens when I play the (flipped) tape in Reverse mode except that now, the right channel is higher and the left channel is lower. However, if I FLIP the tape and play it again, the left channel is now playing about 20dB less than the level it was recorded at and the right channel is playing about 10dB higher than the level it was recorded at. If I playback the tape in the same order as it was recorded (play in direct mode and reverse mode), it plays great, both channels are equal, in both directions, just the way they have been recorded. I record a brand new tape, heads perfectly clean, both channels recorded equal it’s all good. Hello All, my Akai 635D is behaving very strange. Yes, I bought a new amp, TT, EQ, speakers.you only live once. Īt the end of the day, it is your dream and it sounds thirty-something times better than anything you've ever heard. ya all know the story.Īnd then, you realize you can get your dream back and.you realize it's not just the sound (surely, someone's gonna interject saying their whatever-brand R2R sounds better over 16Khz or. It doesn't matter(!)- AT ALL-! It's a dream and, regardless of it being' a money pit, I am re-living it, thirty-something years laterīeing a teenager, I saw it playing Tales from topographic oceans. Most likely, not the cheapest (considering I had to ship it from Japan and pay ScoMo's f'g taxes). This one's not about how good the heads are or how clean or cheap I got it nothing of that sort.
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